CN1748128A - Liquid-detecting device and liquid container with the same - Google Patents

Abstract

A first electrode (46) has a body portion (46a) covering substantially the whole of the area of a recess portion (43), and the body portion (46a) includes a cutout portion (46c). A piezoelectric layer (47) has a body portion (47a) with a diameter smaller than that of the recess portion (43), the entire part of the layer is within the recess portion area, and substantially the whole of the body portion (47a) except the portion corresponding to the cutout portion (46c) is layered over the first electrode (46). An auxiliary electrode (48) extends from the outside up to the inside of the recess portion area, and portion of the auxiliary electrode is positioned inside the cutout portion (46c) of the first electrode (46) and supports portion of the piezoelectric layer (47). A second electrode (49) has a body portion (49a) layered over the piezoelectric layer (47) and an extending portion (49b) extending from the body portion (49a) and connected inside the recess portion area to the auxiliary electrode (48). Condition of residual vibration of a vibrating portion of the liquid-detecting device can be easily and reliably detected, and cracks in the piezoelectric layer can be prevented from occurring.

Description

Liquid detection device and liquid container equipped with the device

technical field

The invention relates to a liquid detection device and a liquid container equipped with the device, in particular to a liquid detection device suitable for detecting the remaining liquid in a liquid injection device and a liquid container equipped with the device.

Background technique

A typical example of a conventional liquid ejecting device is an ink jet recording device equipped with an ink jet recording head for image recording. Other liquid jetting devices can be exemplified, for example: a device equipped with a colored material ejection head used in the manufacture of color filters such as liquid crystal displays; A device equipped with a nozzle for the electrode material (conductive paste) used; a device equipped with a nozzle for living organisms used in biochip manufacturing; a device equipped with a sample nozzle as a precision bulb, etc.

In an inkjet type recording apparatus that is a representative example of a liquid ejection apparatus, an inkjet type recording head having a pressure generating unit that pressurizes a pressure generating chamber and a The pressurized ink is ejected as ink droplets from the nozzle openings.

In an inkjet recording device, ink in an ink tank is continuously supplied to a recording head through a flow path, thereby enabling printing to continue. The ink container is configured as a detachable cartridge, for example, and can be easily replaced by a user when ink is consumed.

In the past, the ink consumption management method of the ink cartridge has the method of accumulating the ejection number of ink droplets on the recording head and the amount of ink sucked out due to maintenance by software, thereby managing the ink consumption through calculation; A method of managing when a predetermined amount of ink is actually consumed by installing an electrode for detecting the liquid level, etc.

However, in the method of managing the ink consumption by calculation by integrating the number of ejected ink droplets or the amount of ink by software, there are the following problems. Among the heads, there are weight deviations in the ejected ink droplets. Although this variation in ink droplet weight does not affect image quality, the ink cartridge is filled with a surplus amount of ink in consideration of the accumulation of errors in the amount of ink consumed due to this variation. Therefore, there is a problem that a surplus amount of ink remains depending on the individual.

On the other hand, the method of managing the timing at which ink is consumed by using the electrodes can detect the actual amount of ink, and therefore can manage the remaining amount of ink with high reliability. However, since the detection of the ink liquid level depends on the conductivity of the ink, the types of inks that can be detected are limited and the sealing structure of the electrodes is complicated. In addition, since the material of the electrodes is usually a noble metal with good conductivity and high corrosion resistance, the manufacturing cost of the ink cartridge is increased. In addition, since two electrodes need to be mounted, the number of manufacturing steps increases, resulting in an increase in manufacturing cost.

A device developed to solve the above problems is disclosed as a piezoelectric device in Japanese Patent Application Laid-Open No. 2001-146024. The piezoelectric device can accurately detect the remaining amount of liquid, does not require a complicated sealing structure, and can be mounted on a liquid container for use.

That is, according to the piezoelectric device described in Japanese Patent Application Laid-Open No. 2001-146024, when there is ink and when there is no ink (or very little) in the space facing the vibrating part of the piezoelectric device, due to the forced The resonant frequency of the residual vibration signal generated by the residual vibration (free vibration) of the vibrating part of the piezoelectric device after vibration changes, and the ink remaining amount in the ink cartridge can be monitored by utilizing this situation.

24A, 24B, and 24C show an actuator constituting the above-mentioned conventional piezoelectric device. This actuator 106 has: a substrate 178 having a circular opening 161 substantially in the center; a vibrating plate 176 disposed on one surface (hereinafter referred to as "surface") of the substrate 178 so as to cover the opening 161; a piezoelectric layer 160 , is disposed on the surface side of the vibrating plate 176; the upper electrode 164 and the lower electrode 166 sandwich the piezoelectric layer 160 from two directions; the upper electrode terminal 168 is electrically combined with the upper electrode 164; the lower electrode terminal 170 is connected to the lower The electrode 166 is electrically connected; and the auxiliary electrode 172 is arranged between the upper electrode 164 and the upper electrode terminal 168 and is electrically connected to both.

The piezoelectric layer 160, the upper electrode 164, and the lower electrode 166 have circular portions as respective main body portions. In addition, each circular portion of the piezoelectric layer 160 , the upper electrode 164 , and the lower electrode 166 forms a piezoelectric element.

The vibrating plate 176 is formed on the surface of the substrate 178 and covers the opening 161 . Cavity 162 is formed by a portion of vibrating plate 176 facing opening 161 and opening 161 of substrate (cavity forming member) 178 . The surface of the substrate 178 opposite to the piezoelectric element (hereinafter referred to as "back surface") faces the inside of the ink container. Thus, the cavity 162 is configured to be in contact with the liquid (ink). In addition, the vibrating plate 176 is attached to the base plate 178 in a liquid-tight manner so that no liquid leaks to the surface side of the base plate 178 even if liquid enters the cavity 162 .

The lower electrode 166 is located on the surface of the vibrating plate 176 . The center of the circular portion which is the main body portion of the lower electrode 166 is fitted to coincide with the center of the opening 161 . In addition, the piezoelectric layer 160 is arranged and formed on the surface side of the lower electrode 166 such that the center of its circular portion coincides with the center of the opening 161 .

Then, in the actuator (piezoelectric device) 106 in the prior art, the size (area) of the circular portion of the lower electrode 166 is set to be smaller than the size (area) of the opening 161, so that the lower electrode 166 The circular portion of is arranged within the range of an area whose entirety corresponds to the opening 161 . In addition, the area of the circular portion of the piezoelectric layer 160 is set to be smaller than the area of the opening 161 and larger than the area of the circular portion of the lower electrode 166 .

The upper electrode 164 is arranged and formed on the surface side of the piezoelectric layer 160 so that the center of the circular part which is the main body thereof coincides with the center of the opening 161 . The area of the circular portion of the upper electrode 164 is set to be smaller than the area of the circular portion of the opening 161 and the piezoelectric layer 160 and larger than the area of the circular portion of the lower electrode 166 .

Therefore, the main body of the piezoelectric layer 160 is sandwiched between the main body of the upper electrode 164 and the main body of the lower electrode 166 from the front side and the back side, respectively. The respective main portions of the piezoelectric layer 160 , the upper electrode 164 , and the lower electrode 166 , that is, the circular portion, form a piezoelectric element in the actuator 106 . The piezoelectric element is connected to the vibrating plate 176 .

Due to this configuration, the vibration area in the vibration plate 176 that actually vibrates is determined by the opening 161 . In addition, among the circular portion of the lower electrode 166 and the circular portion of the upper electrode 164 electrically connected to the piezoelectric layer 160, since the circular portion of the lower electrode 166 is smaller, the circular portion of the lower electrode 166 determines the voltage. The portion of the electrical layer 160 that produces the piezoelectric effect.

As described above, in the actuator 106 (piezoelectric device) in the prior art, the circular body portion of the upper electrode 164, the circular body portion of the piezoelectric layer 160, the circular body portion of the lower electrode 166, and the circle Among the shaped openings 161, the opening 161 has the largest area, the second largest is the main body of the piezoelectric layer 160, the second is the main body of the upper electrode 164, and the smallest is the main body of the lower electrode 166.

In addition, in the above-mentioned actuator 106 in the prior art, the residual vibration (free vibration) of the vibrating part generated after the driving pulse is applied to the piezoelectric element to forcibly vibrate the vibrating part is detected by the same piezoelectric element as the counter electromotive force. from. Then, before and after the liquid level in the ink container passes through the installation position of the actuator 106 (strictly speaking, the position of the cavity 162), the residual vibration state of the vibration part will change, and the ink in the ink container can be detected by using this phenomenon. margin.

However, the above-mentioned conventional liquid detection device (piezoelectric device) has the following problems.

First, the output of the counter electromotive force generated in the piezoelectric element by the residual vibration of the vibrating portion of the liquid detection device is small, thus making detection of the counter electromotive force difficult. This is considered to be because the deformed shape (deformation mode) of the vibrating part when the driving pulse is applied to the piezoelectric element to vibrate forcibly differs greatly from the deformed shape (deformation mode) of the vibrating part when the vibrating part is automatically vibrated after forced deformation. caused by.

Second, in the free vibration of the vibrating part after forced deformation, unnecessary high-order vibration modes are excited in addition to the necessary vibration frequencies to be detected. In particular, if the position of the lower electrode in the vibrating portion is deviated due to manufacturing variation, unnecessary vibration increases, and detection may not be possible or correct detection may not be possible depending on the situation.

24A, 24B, and 24C, in the conventional liquid detection device (piezoelectric device), part of the hard and fragile piezoelectric film 160 extends toward the upper electrode terminal 168 side, and crosses the cavity 162. the edge of. Therefore, cracks are generated on the piezoelectric film 160 at positions corresponding to the edges of the cavity 162 .

Contents of the invention

The present invention has been made in consideration of the above circumstances, and an object of the present invention is to provide a liquid detection device capable of easily and reliably detecting a residual vibration state of a vibrating portion, and a liquid container equipped with the same.

Further, it is an object of the present invention to provide a liquid detection device capable of preventing cracks in the piezoelectric layer and a liquid container equipped with the same.

In order to solve the above-mentioned problems, the liquid detection device of the present invention includes: a base having a first surface and a second surface opposite to each other, and a recess for receiving a medium to be detected is formed so as to open on the first surface side. , and the bottom surface of the concave portion is formed to vibrate; a first electrode, which is formed on the second surface side of the base portion, has a main body portion, wherein the main body portion is larger than the bottom surface of the concave portion formed in a large size so as to cover almost the entire area corresponding to the bottom surface of the concave portion, and the main body portion includes a cutout portion formed by indenting inward from a position corresponding to an edge of the bottom surface of the concave portion; a piezoelectric layer having a main body portion formed in a size smaller than the bottom surface of the concave portion and entirely contained within a region corresponding to the bottom surface of the concave portion, wherein all of the piezoelectric layer The main body part is laminated on the first electrode except for the part corresponding to the cutout part of the first electrode; the auxiliary electrode is formed on the second surface of the base part; side, and extends from the outside of the area corresponding to the bottom surface of the concave portion to the inside of the area corresponding to the bottom surface of the concave portion, and a part thereof is located inside the cutout portion of the first electrode, and extends from the One side of the second face supports a part of the piezoelectric layer; and a second electrode having a main body portion and an extension portion, wherein the main body portion is laminated on the piezoelectric layer, and the extension portion extends from the main body portion out, and is connected to the auxiliary electrode inside a region corresponding to the bottom surface of the concave portion.

Furthermore, it is preferable that the piezoelectric layer has a protruding portion that protrudes from the main body portion of the piezoelectric layer within the range of a region corresponding to the bottom surface of the concave portion, and that the protruding portion supported by the auxiliary electrode.

In addition, it is preferable that the body portion of the second electrode is formed in a smaller size than the body portion of the piezoelectric layer.

Furthermore, it is preferred that the body portion of the piezoelectric layer and the body portion of the second electrode have substantially symmetrical shapes having at least one common axis of symmetry.

In addition, it is preferable that the main body portion of the piezoelectric layer and the main body portion of the second electrode are both circular and arranged concentrically with each other.

In order to solve the above problems, the liquid detection device of the present invention includes: a base having a first surface and a second surface opposite to each other, and a concave portion for receiving a medium to be detected is formed on the first surface. The side is open, and the bottom surface of the concave portion is formed to be vibrated; a first electrode is formed on the side of the second surface of the base portion with a size larger than the bottom surface of the concave portion, so as to cover the entire a region corresponding to the bottom surface of the concave portion; a piezoelectric layer having a main body portion formed in a size smaller than the bottom surface of the concave portion and laminated inside the region corresponding to the bottom surface of the concave portion on the first electrode; and a second electrode having a body portion laminated on the body portion of the piezoelectric layer.

In addition, it is preferable that the piezoelectric layer further has an extension portion extending from the main body portion of the piezoelectric layer, and extending beyond a position corresponding to the edge of the concave portion to a position corresponding to the concave portion. The outside of the area corresponding to the bottom surface of the concave portion.

In addition, it is preferable that the body portion of the second electrode is formed in a smaller size than the body portion of the piezoelectric layer.

In addition, preferably, the second electrode further has an extension portion, the extension portion extends from the main body portion of the second electrode, extends through the upper portion of the extension portion of the piezoelectric layer, and extends to the outside of the area corresponding to the bottom surface of the recess.

Furthermore, it is preferred that the body portion of the piezoelectric layer and the body portion of the second electrode have substantially symmetrical shapes having at least one common axis of symmetry.

Furthermore, it is preferable that the concave portion, the main body portion of the piezoelectric layer, and the main body portion of the second electrode are all circular and arranged concentrically with each other.

Furthermore, it is preferable to further include an insulating layer interposed between the extension portion of the second electrode and the piezoelectric layer.

In order to solve the above-mentioned problems, the liquid detection device of the present invention includes: a base having a first surface and a second surface opposite to each other, and a recess for receiving a medium to be detected is formed so as to open on the first surface side. , and the bottom surface of the concave portion is formed to vibrate; a first electrode is formed on the side of the second surface of the base portion with a size larger than the bottom surface of the concave portion so as to cover the entire contact with the concave portion a region corresponding to the bottom surface; a piezoelectric layer having a main body portion formed in a size larger than the bottom surface of the concave portion and stacked on the entire region corresponding to the bottom surface of the concave portion; on the first electrode; and a second electrode having a body portion formed in a size smaller than the bottom surface of the concave portion and stacked on the inside of a region corresponding to the bottom surface of the concave portion on the body portion of the piezoelectric layer.

In addition, it is preferable that the body portion of the piezoelectric layer is formed in a smaller size than the body portion of the first electrode.

In addition, preferably, the piezoelectric layer further has an extension portion extending from the main body portion of the piezoelectric layer; the second electrode further has an extension portion, and the extension portion extends from the second electrode The main body portion extends out and extends through the main body portion and the upper portion of the extension portion of the piezoelectric layer.

Furthermore, it is preferred that the body portion of the piezoelectric layer and the body portion of the second electrode have substantially symmetrical shapes having at least one common axis of symmetry.

In addition, it is preferable that both the concave portion and the main body portion of the second electrode are circular and arranged concentrically with each other.

Furthermore, it is preferable to further include an insulating layer interposed between the extension portion of the second electrode and the piezoelectric layer.

In order to solve the above-mentioned problems, the liquid detection device of the present invention includes: a base having a first surface and a second surface opposite to each other, and a recess for receiving a medium to be detected is formed so as to open on the first surface side. , and the bottom surface of the concave portion is formed to vibrate; a first electrode having a main body portion formed on the second surface side of the base with a size smaller than the bottom surface of the concave portion, and disposed inside a region corresponding to the bottom surface of the concave portion; a piezoelectric layer having a body portion formed in a size smaller than that of the body portion of the first electrode, and stacked on the body portion of the first electrode; and a second electrode having a body portion formed in a smaller size than the body portion of the piezoelectric layer and stacked on on the body portion of the piezoelectric layer.

In addition, it is preferable that the first electrode further has an extension portion extending from the main body portion of the first electrode and extending to the outside of a region corresponding to the bottom surface of the concave portion; The piezoelectric layer further has an extension portion extending from the body portion of the piezoelectric layer and extending to the outside of a region corresponding to the bottom surface of the recess; the second electrode further has an extension part, the extension part extends from the main part of the second electrode, and extends through the main part of the piezoelectric layer and the upper part of the extension part.

In addition, it is preferable that both the concave portion and the main body portion of the first electrode are circular and arranged concentrically with each other; the diameter of the main body portion of the first electrode is the size of the 75% or more of the diameter of the recess.

In order to solve the above-mentioned problems, the liquid detection device of the present invention includes: a base having a first surface and a second surface opposite to each other, and a recess for receiving a medium to be detected is formed so as to open on the first surface side. , and the bottom surface of the concave portion is formed to vibrate; a first electrode is formed on the side of the second surface of the base portion with a size larger than the bottom surface of the concave portion so as to cover the entire contact with the concave portion a region corresponding to the bottom surface; a piezoelectric layer having a main body portion formed in a size larger than the bottom surface of the concave portion and stacked on the entire region corresponding to the bottom surface of the concave portion; on the first electrode; and a second electrode having a ring-shaped main body portion formed with an outer ring diameter smaller than the bottom surface of the concave portion in a region corresponding to the bottom surface of the concave portion An inner lamination is on the body portion of the piezoelectric layer.

In addition, it is preferable that the body portion of the piezoelectric layer is formed in a smaller size than the body portion of the first electrode.

In addition, preferably, the piezoelectric layer further has an extension portion extending from the main body portion of the piezoelectric layer; the second electrode further has an extension portion, and the extension portion extends from the second electrode The main body portion extends out and extends through the main body portion and the upper portion of the extension portion of the piezoelectric layer.

Furthermore, it is preferred that the body portion of the piezoelectric layer and the body portion of the second electrode have substantially symmetrical shapes having at least one common axis of symmetry.

In addition, it is preferable that the concave portion is circular; the main body portion of the second electrode is circular; and the concave portion and the main body portion of the second electrode are arranged concentrically with each other.

In order to solve the above-mentioned problems, the liquid detection device of the present invention includes: a base having a first surface and a second surface opposite to each other, and a recess for receiving a medium to be detected is formed so as to open on the first surface side. , and the bottom surface of the concave portion is formed to vibrate; a first electrode is formed on the second surface side of the base portion and has a main body portion and an extension portion, wherein the main body portion is larger than the The bottom surface of the concave portion is formed with a small size, and is arranged inside a region corresponding to the bottom surface of the concave portion, and the extension portion extends from the main body portion and extends to a region corresponding to the bottom surface of the concave portion. outside; a piezoelectric layer formed with a size smaller than the bottom surface of the concave portion and stacked on the first electrode, all of which are arranged inside a region corresponding to the bottom surface of the concave portion an auxiliary electrode formed on the second surface side of the base and extending from the outside of the region corresponding to the bottom surface of the concave portion to the inside of the region corresponding to the bottom surface of the concave portion, and a part thereof extends from a part of the piezoelectric layer supported on one side of the second surface; and a second electrode having a main body portion and an extension portion, wherein the main body portion is laminated on the piezoelectric layer, and the extension portion extends from the main body. A portion protrudes and is connected to the auxiliary electrode inside a region corresponding to the bottom surface of the concave portion.

In addition, it is preferable that the size of the body part of the first electrode is smaller than the size of the piezoelectric layer; the size of the body part of the second electrode is smaller than the size of the body of the first electrode. Portion size is large.

In addition, it is preferable that the main body portion of the second electrode has a smaller size than the piezoelectric layer.

In addition, it is preferable that the extension portion of the first electrode and the extension portion of the second electrode extend in opposite directions to each other on a first straight line passing through the center of the concave portion; An electrode further has a pair of extending portions opposite to each other from the main body portion of the first electrode on a second straight line passing through the center of the concave portion and perpendicular to the first straight line. direction extension.

Furthermore, it is preferable that the pair of extension portions are separated from the main body portion of the first electrode.

In addition, it is preferable that the main body portion of the first electrode, the main body portion of the piezoelectric layer, and the main body portion of the second electrode are all circular and arranged concentrically with each other. .

In order to solve the above problems, the liquid container of the present invention is characterized by comprising a container body for storing liquid and any one of the liquid detection devices, wherein the recessed portion of the liquid detection device is exposed to the liquid in the container body in the storage space.

In addition, it is preferable that a liquid for a liquid ejection device is stored in the container main body.

In addition, it is preferable that the liquid ejection device is an inkjet type recording device; ink is stored in the container main body.

According to the liquid detection device and the liquid container equipped with the same in the present invention constituted as described above, it is possible to easily and reliably detect a change in the residual vibration state of the vibrating portion of the liquid detection device.

Furthermore, according to the liquid detection device and the liquid container equipped with the same in the present invention, the occurrence of cracks in the piezoelectric layer can be reliably prevented.

Description of drawings

1 is a perspective view showing a schematic configuration of an ink jet recording apparatus using an ink cartridge having a liquid detection device according to an embodiment of the present invention;

2 is a plan view showing a liquid detection device according to an embodiment of the present invention;

3A and FIG. 3B are enlarged longitudinal sectional views showing a part of the liquid detection device shown in FIG. 2, FIG. 3A shows a section along the A-A line of FIG. 2, and FIG. section;

Fig. 4 is a schematic diagram of the periphery of the liquid detection device shown in Fig. 2, Fig. 3A and Fig. 3B and its equivalent circuit;

Fig. 5 A shows the relationship between the resonant frequency of the vibrating part detected by the liquid detection device shown in Fig. 2, Fig. 3A and Fig. 3B and the remaining amount of ink in the ink cartridge;

Figure 5B shows the relationship between the resonance frequency of the ink detected by the liquid detection device shown in Figure 2, Figure 3A and Figure 3B and the ink density;

6A and 6B are schematic diagrams of back electromotive force waveforms in the liquid detection device shown in FIG. 2, FIG. 3A and FIG. 3B;

Fig. 7 is a perspective view showing a module body incorporating the liquid detection device shown in Fig. 2, Fig. 3A and Fig. 3B;

Fig. 8 is an exploded view showing the structure of the module body shown in Fig. 7;

Fig. 9 is a schematic diagram of an example of a section of the module body shown in Fig. 7 mounted on the container main body of the ink cartridge;

10 is a plan view showing a liquid detection device according to an embodiment of the present invention;

11A and FIG. 11B are enlarged longitudinal sectional views showing a part of the liquid detection device shown in FIG. 10. FIG. 11A shows a section along the A-A line of FIG. section;

Fig. 12 is a cross-sectional view of a modified example of the liquid detection device shown in Fig. 10, Fig. 11A and Fig. 11B;

13 is a plan view showing a liquid detection device according to an embodiment of the present invention;

14A and 14B are enlarged longitudinal sectional views showing a part of the liquid detection device shown in FIG. 13 , and FIG. 14A shows a section along the line A-A of FIG. 13 , and FIG. 14B shows a section along the line B-B of FIG. 13 . section;

Fig. 15 is a cross-sectional view of a modified example of the liquid detection device shown in Fig. 13, Fig. 14A and Fig. 14B;

16 is a plan view showing a liquid detection device according to an embodiment of the present invention;

17A and FIG. 17B are enlarged longitudinal sectional views showing a part of the liquid detection device shown in FIG. 16. FIG. 17A shows a section along the A-A line of FIG. section;

18 is a plan view showing a liquid detection device according to an embodiment of the present invention;

19A and FIG. 19B are enlarged longitudinal sectional views showing a part of the liquid detection device shown in FIG. 18. FIG. 19A shows a section along the A-A line of FIG. 18, and FIG. 19B shows a section along the B-B line of FIG. section;

20 is a plan view showing a liquid detection device according to an embodiment of the present invention;

21A and 21B are enlarged longitudinal sectional views showing a part of the liquid detection device shown in FIG. 20 , and FIG. 21A shows a section along line A-A of FIG. 20 , and FIG. 21B shows a section along line B-B of FIG. 20 ;

22 is a plan view showing a liquid detection device as a modified example of the embodiment shown in FIGS. 20 , 21A, and 21B;

23A and 23B are enlarged longitudinal sectional views showing a part of the liquid detection device shown in FIG. 22. FIG. 23A shows a section along the line A-A in FIG. 22, and FIG. 23B shows a section along the line B-B in FIG. cross section;

24A, 24B and 24C are schematic diagrams of a conventional liquid detection device.

Detailed ways

Next, a liquid detection device and an ink cartridge (liquid container) equipped with the liquid detection device according to an embodiment of the present invention will be described with reference to the drawings.

Fig. 1 shows the schematic structure of the inkjet type recording device (liquid ejection device) using the ink cartridge of this embodiment, and the numeral 1 in Fig. And it is guided by the guide member 4 to reciprocate in the axial direction of the drum 5 .

An inkjet type recording head 12 is mounted on the side of the carriage 1 facing the recording paper 6 , and an ink cartridge 7 for supplying ink to the recording head 12 is detachably attached to the upper portion thereof.

In the non-printing area of the recording device, that is, at the home position (right side in the figure), a cover member 31 is arranged. When the recording head loaded on the carriage 1 moves to the home position, the cover member 31 covers the recording head. The nozzle forming surface of the head, thereby forming a sealed space between it and the nozzle forming surface. In addition, the pump unit 10 is arranged below the cover member 31 for applying negative pressure to the sealed space formed by the cover member 31 to perform cleaning and the like.

In addition, in the vicinity of the printing area side in the cover member 31, a wiping device 11 with an elastic plate such as rubber is arranged, and this wiping device 11 can advance and retreat in the horizontal direction, for example, with respect to the moving track of the recording head. When the carriage 1 reciprocates on the cover member 31 side, it is possible to wipe the nozzle formation surface of the recording head as necessary.

2 , FIG. 3A and FIG. 3B are schematic diagrams of a liquid detection device 60 according to this embodiment. The liquid detection device 60 has a base 40 formed by laminating a vibrating plate 42 on a substrate 41, and the base 40 has first surfaces facing each other. 40a and the second surface 40b. A circular cavity (recess) 43 is formed in the base 40 for receiving a medium to be detected, and the cavity 43 is opened on the first surface 40a side, and the bottom surface portion 43a of the cavity 43 is formed so that a vibrating plate can pass through it. 42 vibrations. In other words, the portion of the entire vibrating plate 42 that actually vibrates is defined by the cavity 43 . A lower electrode terminal 44 and an upper electrode terminal 45 are formed at both ends of the base 40 on the second surface 40 b side.

On the second face 40b of the base 40 is formed a lower electrode (first electrode) 46 having an approximately circular main body portion 46a and an extension portion 46b extending from the main body portion 46a to The direction of the lower electrode terminal 44 extends and is connected to the lower electrode terminal 44 . The center of the approximately circular body portion 46 a of the lower electrode 46 coincides with the center of the cavity 43 .

The approximately circular body portion 46 a of the lower electrode 46 is formed to have a larger diameter than the circular cavity 43 and covers almost all of the area corresponding to the cavity 43 . In addition, the substantially circular main body portion 46 a of the lower electrode 46 includes a notch portion 46 c recessed inwardly from a position corresponding to the edge 43 a of the cavity 43 .

Over the lower electrode 46 is laminated a piezoelectric layer 47 having a circular main body portion 47a having a diameter smaller than that of the cavity 43, and a protrusion protruding from the main body portion 47a within the range of the region corresponding to the cavity 43. Section 47b. It can be seen from FIG. 2 that the entire piezoelectric layer 47 is accommodated within the area corresponding to the cavity 43 . In other words, the piezoelectric layer 47 is completely free from a portion that traverses and extends past a position corresponding to the edge 43 a of the cavity 43 .

The center of the main body part 47a of the piezoelectric layer 47 coincides with the center of the cavity 43, and the main body part 47a of the piezoelectric layer 47 is laminated on the lower part except for the part corresponding to the cutout part 46c of the lower electrode 46. on electrode 46.

An auxiliary electrode 48 is formed on the second surface 40 b side of the base 40 . The auxiliary electrode 48 extends from the outside of the region corresponding to the cavity 43 over the position corresponding to the edge 43 a of the cavity 43 to the inside of the region corresponding to the cavity 43 . Part of the auxiliary electrode 48 is located inside the notch 46 c of the first electrode 46 , and supports the extension 47 b of the piezoelectric layer 47 and its vicinity from the second surface 40 b side of the substrate 40 . The auxiliary electrode 48 preferably has the same material and thickness as the lower electrode 46 . In this way, since the extension portion 47b of the piezoelectric layer 47 and its vicinity are supported by the auxiliary electrode 48 from the side of the second surface 40b of the substrate 40, no step difference occurs on the piezoelectric layer 47, thereby preventing a decrease in mechanical strength. .

A circular main body portion 49 a of an upper electrode (second electrode) 49 formed to have a smaller diameter than the main body portion 47 a of the piezoelectric layer 47 is laminated on the piezoelectric layer 47 . In addition, the upper electrode 49 has an extension portion 49 b extending from the main body portion 49 a and connected to the auxiliary electrode 48 . It can be seen from FIG. 3B that the position P where the connection between the extension portion 49 b of the upper electrode 49 and the auxiliary electrode 48 starts is located within the area corresponding to the cavity 43 .

As can be seen from FIG. 2 , the upper electrode 49 is electrically connected to the upper electrode terminal 45 via the auxiliary electrode 48 . Connecting the upper electrode 49 to the upper electrode terminal 45 via the auxiliary electrode 48 in this way allows both the upper electrode 49 and the auxiliary electrode 48 to absorb a step due to the total thickness of the piezoelectric layer 47 and the lower electrode 46 . Therefore, it is possible to prevent a large step difference from being generated on the upper electrode 49 , resulting in a decrease in mechanical strength.

The body portion 49 a of the upper electrode 49 is formed in a circular shape, and its center coincides with the center of the cavity 43 . The main body portion 49 a of the upper electrode 49 is formed to have a smaller diameter than both the main body portion 47 a of the piezoelectric layer 47 and the cavity 43 .

In this way, the main body portion 47 a of the piezoelectric layer 47 is sandwiched between the main body portion 49 a of the upper electrode 49 and the main body portion 46 a of the lower electrode 46 . Thereby, the piezoelectric layer 47 can be efficiently deformed and driven.

In addition, among the main body portion 46 a of the lower electrode 46 and the main body portion 49 a of the upper electrode 49 electrically connected to the piezoelectric layer 47 , the diameter of the main body portion 49 a of the upper electrode 49 is smaller. Therefore, the main body portion 49 a of the upper electrode 49 defines the range of the portion where the piezoelectric effect is generated in the piezoelectric layer 47 .

In addition, the components included in the liquid detection device 60 are preferably integrally formed with each other by sintering. By integrally forming the liquid detection device 60 in this way, the handling of the liquid detection device 60 can be facilitated.

The piezoelectric layer 47 is preferably made of lead zirconate titanate (PZT), lead lanthanum zirconate titanate (PLZT), or a lead-free piezoelectric film that does not use lead. The material of the substrate 41 is preferably zirconia or alumina. In addition, it is preferable to use the same material as the substrate 41 for the vibrating plate 42 . The upper electrode 49 , the lower electrode 46 , the upper electrode terminal 45 , and the lower electrode terminal 44 can be made of conductive materials, such as metals such as gold, silver, copper, platinum, aluminum, and nickel.

As for the main body portion 47 a of the piezoelectric layer 47 , the main body portion 49 a of the upper electrode 49 , and the main body portion 46 a of the lower electrode 46 , their centers coincide with the center of the cavity 43 . Furthermore, the center of the circular cavity 43 defining the vibrator portion of the vibrating plate 42 is located on the center of the entire liquid detection device 60 .

The vibrating part of the vibrating plate 42 defined by the cavity 43, the part corresponding to the cavity 43 of the main part 46a of the lower electrode 46, the main part 47a and the protruding part 47b of the piezoelectric layer 47, and the main part 49a and A portion of the extension portion 49 b corresponding to the cavity 43 constitutes the vibrating portion 61 of the liquid detection device 60 . In addition, the center of the vibrating portion 61 of this liquid detection device 60 coincides with the center of the liquid detection device 60 .

In addition, the main body portion 47a of the piezoelectric layer 47, the main body portion 49a of the upper electrode 49, the main body portion 46a of the lower electrode 46, and the vibrator portion of the vibrating plate 42 (that is, the portion corresponding to the bottom surface portion 43a of the cavity 43) have circular shapes. shape, and the entire piezoelectric layer 47, that is, the main body portion 47a and the extension portion 47b of the piezoelectric layer 47 are arranged inside the area corresponding to the cavity 43, so that the vibrating portion 61 of the liquid detection device 60 is relative to the liquid The detection device 60 has a substantially symmetrical shape to the center.

In this way, in this embodiment, since the main body portion 46a of the lower electrode 46 covers almost the entire area corresponding to the cavity 43, the deformation mode during forced vibration and the deformation mode during free vibration are reduced compared with conventional ones. difference between. In addition, since the vibrating portion 61 of the liquid detection device 60 has a symmetrical shape with respect to the center of the liquid detection device 60 , the rigidity of the vibrating portion 61 is substantially isotropic when viewed from the center.

Therefore, occurrence of unnecessary vibration due to structural asymmetry is suppressed, and output reduction of counter electromotive force due to difference in deformation mode between when forced to vibrate and when freely vibrated is prevented. Thereby, the detection accuracy of the resonance frequency of the residual vibration in the vibrating portion 61 of the liquid detection device 60 is improved, and the detection of the residual vibration of the vibrating portion 61 is also facilitated.

In addition, since the main body portion 46a of the lower electrode 46 having a larger diameter than the cavity 43 covers almost the entire area corresponding to the cavity 43, unnecessary vibrations due to position deviation of the lower electrode 46 during manufacture can be prevented from occurring, A decrease in detection accuracy can be prevented.

In addition, the entire piezoelectric layer 47 that is hard and fragile is arranged inside the region corresponding to the cavity 43 so that the piezoelectric layer 47 does not exist at a position corresponding to the edge 43 a of the cavity 43 . Therefore, there is no problem of cracking of the piezoelectric film that occurs at positions corresponding to the edges of the cavity in conventional liquid detection devices.

In addition, since the range where the vibrating portion 61 is in contact with the liquid is limited to the range where the cavity 43 exists, liquid detection can be performed accurately, whereby the ink level in the ink cartridge 7 can be detected with high precision.

FIG. 4 shows a liquid detection device 60 used in this embodiment and its equivalent circuit. The liquid detection device 60 detects the change of the acoustic impedance by detecting the resonant frequency of the residual vibration, thereby detecting the consumption state of the liquid in the ink cartridge.

FIG. 4(A) and FIG. 4(B) show an equivalent circuit of the liquid detection device 60 . In addition, Fig. 4 (C) and Fig. 4 (D) respectively show when the ink cartridge 7 is full of ink, including the periphery of the liquid detection device 60 and its equivalent circuit, Fig. 4 (E) and Fig. 4 (F) respectively shows the periphery including the liquid detection device 60 and its equivalent circuit when the ink cartridge 7 is empty of ink.

The liquid detecting device 60 shown in FIGS. 2 to 4 is installed at a predetermined place of the container body of the ink cartridge 7 so that the cavity 43 is in contact with the liquid (ink) stored in the container body. That is, at least a part of the vibration part 61 of the liquid detection device 60 is exposed in the storage space of the container main body. When the liquid is sufficiently stored in the container main body, the inside and outside of the cavity 43 are filled with the liquid.

On the other hand, when the liquid (ink) inside the container main body of the ink cartridge 7 is consumed, and the liquid level falls below the installation position of the liquid detection device 60 (strictly speaking, the position of the cavity 43), the cavity 43 is formed. A state where no liquid exists inside, or a state where only liquid remains in the chamber 43 and gas exists outside it.

The liquid detection device 60 detects the difference in acoustic impedance caused by the state change. Thereby, the liquid detection device 60 can detect whether the liquid is fully stored in the container main body or whether a certain amount or more of the liquid is consumed.

Next, the principle of liquid level detection in the liquid detection device 60 of this embodiment will be described.

The liquid detection device 60 can use the change of the resonance frequency to detect the change of the acoustic impedance of the liquid. The resonance frequency can be detected by measuring a counter electromotive force generated by residual vibration remaining on the vibration part 61 of the liquid detection device 60 after the vibration part 61 has been vibrated. That is, if the vibrating portion 61 is freely vibrated after the vibrating portion 61 is forced to vibrate by applying a drive pulse to the piezoelectric layer 47 of the liquid detection device 60, due to the residual vibration (free vibration) in the vibrating portion 61 of the liquid detection device 60 ), the piezoelectric layer 47 generates a counter electromotive force. The magnitude of this counter electromotive force varies according to the amplitude of the vibrating portion 61 of the liquid detection device 60 . Therefore, the larger the amplitude of the residual vibration (free vibration) of the vibrating portion 61 of the liquid detection device 60 is, the easier it is to detect the output of the counter electromotive force.

Furthermore, the period at which the magnitude of the counter electromotive force changes varies according to the frequency of residual vibration in the vibrating portion 61 of the liquid detection device 60 . That is, the frequency of the vibrating portion 61 of the liquid detection device 60 corresponds to the frequency of the counter electromotive force. Here, the resonance frequency refers to the frequency at which the vibrating part 61 of the liquid detection device 60 and the medium connected to the vibrating part 61 are in a resonant state.

When liquid (ink) was fully stored in the container main body of the ink cartridge 7, the cavity 43 of the liquid detection device 60 was filled with liquid, and the vibrating portion 61 was in contact with the liquid in the container main body through the bottom surface portion 43a of the cavity 43. On the other hand, when the liquid in the container body is not sufficient, the vibrating part 61 of the liquid detection device 60 contacts the remaining liquid in the chamber 43, or contacts the gas or vacuum instead of the liquid.

Here, referring to FIG. 2 to FIG. 4 , the operation and principle of detecting the liquid state in the container body of the ink cartridge 7 will be described from the resonance frequency of the medium and the vibrating part 61 of the liquid detection device 60 obtained by measuring the counter electromotive force.

In the liquid detection device 60 , voltages are applied to the upper electrode 49 and the lower electrode 46 via the upper electrode terminal 45 and the lower electrode terminal 44 , respectively. Then, an electric field is generated in the portion of the piezoelectric layer 47 sandwiched between the upper electrode 49 and the lower electrode 46 . The piezoelectric layer 47 is deformed by this electric field. Due to the deformation of the piezoelectric layer 47, the vibration region (the region corresponding to the bottom surface portion 43a of the cavity 43) in the vibration plate 42 undergoes flexural vibration. After the piezoelectric layer 47 is forcibly deformed, flexural vibration remains in the vibrating portion 61 of the liquid detection device 60 for a period of time.

This residual vibration is free vibration of the vibrating portion 61 of the liquid detection device 60 and the medium. Therefore, by making the voltage applied to the piezoelectric layer 47 a pulse waveform or a rectangular wave, it is possible to easily obtain a resonance state between the vibrating portion 61 and the medium after the voltage is applied. The residual vibration is vibration of the vibrating portion 61 of the liquid detection device 60 accompanied by deformation of the piezoelectric layer 47 . Therefore, the piezoelectric layer 47 generates counter electromotive force along with the residual vibration. This counter electromotive force can be detected via the upper electrode 49 , the lower electrode 46 , the upper electrode terminal 45 , and the lower electrode terminal 44 . Since the resonance frequency can be determined from the detected counter electromotive force, the presence or absence of liquid (ink) in the container body of the ink cartridge 7 can be detected based on the resonance frequency.

Generally, the resonant frequency fs can be expressed by the following formula:

fs=1/(2*π*(M*Cact) ^1/2 ) (Formula 1).

Here, M is the sum of the inertia Mact of the vibrating portion 61 and the additional inertia M'. Cact is the compliance of the vibrating portion 61 .

4(A) and 4(B) are equivalent circuits of the vibrating portion 61 of the liquid detection device 60 and the chamber 43 when no ink remains in the chamber 43 .

Mact is obtained by dividing the product of the thickness of the vibrating portion 61 and the density of the vibrating portion 61 by the area of the vibrating portion 61. Specifically, it is shown in (A) of FIG. 4 and can be represented by the following formula:

Mact=Mpzt+Melectrode1+Melectrode2+Mvib (Formula 2).

Here, Mpzt is obtained by dividing the product of the thickness of the piezoelectric layer 47 and the density of the piezoelectric layer 47 in the vibrating portion 61 by the area of the piezoelectric layer 47 . Melectrode1 is obtained by dividing the product of the thickness of the upper electrode 49 and the density of the upper electrode 49 in the vibrating portion 61 by the area of the upper electrode 49 . Melectrode2 is obtained by dividing the product of the thickness of the lower electrode 46 and the density of the lower electrode 46 in the vibrating portion 61 by the area of the lower electrode 46 . Mvib is obtained by dividing the product of the thickness of the vibrating plate 42 and the density of the vibrating plate 42 in the vibrating portion 61 by the area of the vibrating region of the vibrating plate 42 .

Here, in order to be able to calculate Mact from the overall thickness, density, and area of the vibrating portion 61, it is preferable that the respective areas of the vibration regions of the piezoelectric layer 47, the upper electrode 49, the lower electrode 46, and the vibrating plate 42 have the above-mentioned size. relationship, but the difference in area between them is very small.

In addition, in this embodiment, regarding the piezoelectric layer 47, the upper electrode 49, and the lower electrode 46, it is preferable that the parts other than the circular main body parts 47a, 49a, and 46a, which are their main parts, be smaller than the main parts. negligible extent. Therefore, in the liquid detection device 60 , Mact is the sum of the respective inertias of the upper electrode 49 , the lower electrode 46 , the piezoelectric layer 47 , and the vibrating regions in the vibrating plate 42 . In addition, the compliance Cact is the compliance of a portion formed by the upper electrode 49 , the lower electrode 46 , the piezoelectric layer 47 , and the vibration region in the vibration plate 42 .

In addition, (A), (B), (D), and (F) of FIG. 4 show the equivalent circuits of the vibrating part 61 and the cavity 43 of the liquid detection device 60. In these equivalent circuits, Cact represents the liquid detection The compliance of the vibrating portion 61 of the device 60. Cpzt, Celectrode1, Celectrode2, and Cvib represent the compliance of the piezoelectric layer 47, the upper electrode 49, the lower electrode 46, and the vibration plate 42 in the vibrating portion 61, respectively. Cact can be expressed by the following formula 3:

1/Cact＝(1/Cpzt)+(1/Celectrode1)+(1/Celectrode2)

+(1/Cvib) (Formula 3).

(A) of FIG. 4 can also be expressed as (B) of FIG. 4 by formula (2) and formula (3).

The flexibility Cact indicates the volume of the medium that can be tolerated when pressure is applied per unit area. That is, the flexibility Cact indicates the ease of deformation.

(C) of FIG. 4 shows a cross-sectional view of the liquid detection device 60 when the liquid is sufficiently stored in the container body of the ink cartridge 7 and the liquid is filled to the periphery of the vibrating portion 61 of the liquid detection device 60 . M'max in (C) of FIG. The maximum value obtained by dividing the mass affected by the vibration) by the square of the area. M'max can be expressed by the following formula:

M'max=(π*ρ/(2*k ³ ))*(2*(2*k*a) ³ /(3*π))/(π*a ² ) ² (Formula 4),

(a is the radius of the vibrating part, ρ is the density of the medium, and k is the wave number).

Furthermore, Formula 4 holds true when the vibrating portion 61 of the liquid detection device 60 is a circle with a radius a. The additional moment of inertia M' is an amount representing an apparent increase in the mass of the vibrating portion 61 by the medium located near the vibrating portion 61. As can be seen from Equation 4, M'max varies greatly depending on the radius a of the vibrating portion 61 and the density ρ of the medium.

The wave number k can be expressed by the following formula:

k=2*π*fact/c (Formula 5),

(fact is the resonance frequency of the vibrating portion 61. C is the speed of sound propagating in the medium).

(D) of Fig. 4 shows the equivalent circuit of the vibrating part 61 and the cavity 43 of the liquid detection device 60 in the case of (C) of Fig. 4, wherein the case of (C) of Fig. 4 refers to The liquid is sufficiently stored in the container body of the ink cartridge 7 , and the liquid is filled up to the periphery of the vibrating portion 61 of the liquid detection device 60 .

(E) of FIG. 4 shows a sectional view of the liquid detecting device 60 in a case where there is no liquid around the vibrating portion 61 of the liquid detecting device 60 although the liquid in the container main body of the ink cartridge 7 is consumed. , but liquid remains in the cavity 43 of the liquid detection device 60 .

Equation 4 is an equation representing the maximum moment of inertia M'max determined by the density ρ of ink and the like when the container body of the ink cartridge 7 is filled with liquid. On the other hand, when the liquid in the container main body is consumed and the liquid around the vibrating portion 61 of the liquid detection device 60 is replaced with gas or vacuum while the liquid remains in the cavity 43, the additional inertia M' is generally reduced. Expressed as (more specifically please refer to formula 8 below):

M'=ρ*t/S (Formula 6).

Here, t is the thickness of the medium participating in the vibration. S is the area of the vibrating portion 61 of the liquid detection device 60 . When the vibrating portion 61 is a circle with a radius a, S=π*a ² .

Therefore, when the liquid is sufficiently stored in the container body and the liquid is filled up to the periphery of the vibrating portion 61 of the liquid detection device 60, the additional inertia M' is calculated according to Equation 4. And when the liquid is consumed and the liquid around the vibrating portion 61 of the liquid detection device 60 is replaced with gas or vacuum while remaining liquid in the chamber 43, it is calculated according to Equation 6.

Here, as in (E) of FIG. 4 , although the liquid in the container main body of the ink cartridge 7 is consumed, so that there is no liquid around the vibrating portion 61 of the liquid detection device 60, there remains in the cavity 43 of the liquid detection device 60. In the case of liquid, for convenience, the additional inertia M' in this case is taken as M'cav to distinguish it from the additional inertia M'max when the vibrating part 61 of the liquid detection device 60 is filled with liquid.

(F) of FIG. 4 shows the equivalent circuit of the vibrating portion 61 and the cavity 43 of the liquid detection device 60 in the case of (E) of FIG. 4, wherein the case of (E) of FIG. The liquid in the main body of the container is consumed, so that there is no liquid around the vibrating portion 61 of the liquid detection device 60 , but liquid still remains in the chamber 43 of the liquid detection device 60 .

Here, the parameters related to the state of the medium are the density ρ of the medium and the thickness t of the medium in Equation 6. When the liquid is sufficiently stored in the container main body, the liquid comes into contact with the vibrating portion 61 of the liquid detection device 60 . On the other hand, when the liquid is not sufficiently stored in the container main body, the liquid remains inside the cavity 43, or the vibrating portion 61 of the liquid detection device 60 is in contact with gas or vacuum. The liquid at the periphery of the liquid detection device 60 is consumed, so that the additional inertia M'var in the process from M'max in (C) of FIG. 4 to M'cav in (E) of FIG. 4 increases with the density ρ of the medium and the thickness t of the medium, wherein the density ρ of the medium and the thickness t of the medium vary according to the storage state of the liquid in the container body. Accordingly, the resonance frequency fs also changes. Therefore, the amount of liquid in the container body can be detected by determining the resonance frequency fs.

Here, as shown in (E) of Figure 4, when t=d, if formula 6 is used to represent M'cav, then the depth d of the cavity is substituted into t of formula 6, then:

M'cav=ρ*d/S (Formula 7).

In addition, if the media are liquids of different types, the density ρ is different depending on the composition, so the additional inertia M' and the resonance frequency fs are also different. Therefore, the type of liquid can be detected by determining the resonance frequency fs.

FIG. 5A is a graph showing the relationship between the amount of ink in the container body of the ink cartridge 7 and the resonance frequency fs of the ink and the vibrating portion. The vertical axis represents the resonance frequency fs, and the horizontal axis represents the amount of ink.

When ink is fully stored in the container body of the ink cartridge 7 and the periphery of the vibrating portion 61 of the liquid detection device 60 is filled with ink, the maximum additional inertia M'max is a value represented by formula 4. On the other hand, when the ink is consumed and ink remains in the chamber 43 while the ink is not filled to the periphery of the vibrating portion 61 of the liquid detection device 60, the additional inertia M'var can be expressed by Equation 6 based on the thickness t of the medium Calculated. Since t in formula 6 is the thickness of the medium participating in the vibration, so by reducing the depth d of the cavity 43 of the liquid detection device 60 of the residual ink, that is, making the thickness of the substrate 41 thin enough, the process of gradually consuming the ink can also be reduced. Detection is performed (see (C) of FIG. 4 ). Here, t ink is set as the thickness of the ink participating in the vibration, and t ink-max is set as the t ink in M'max.

For example, the liquid detection device 60 is disposed on the bottom surface of the ink cartridge substantially horizontally with respect to the liquid surface of the ink. At this time, if the ink is consumed and the liquid level of the ink changes from the liquid detection device 60 to below the height of tink-max, M'var gradually changes according to Formula 6, and the resonance frequency fs gradually changes according to Formula 1. Therefore, as long as the liquid level t of the ink is within the range of t, the liquid level detection device 60 can gradually detect the consumption state of the ink.

Alternatively, the liquid detection device 60 is disposed on the side wall of the ink cartridge substantially perpendicular to the liquid surface of the ink. At this time, when the ink is consumed and the liquid level of the ink reaches the vibrating portion 61 of the liquid detection device 60, the additional inertia M' decreases as the liquid level decreases. Thus, the resonance frequency fs gradually increases according to Formula 1. Therefore, as long as the liquid level of the ink is within the range of the diameter 2a of the chamber 43 (see FIG. 4(C)), the liquid detection device 60 can gradually detect the consumption state of the ink.

Curve X in Fig. 5A shows that when the cavity 43 of the liquid detection device 60 disposed on the bottom surface is shallow enough, or when the vibrating portion 61 of the liquid detection device 60 disposed on the side wall is sufficiently large or long, The relationship between the amount of stored ink and the resonance frequency fs of the ink and the vibrating portion 61. Accordingly, it can be understood that the resonance frequency fs of the ink and the vibrating portion 61 gradually changes while the amount of ink in the container main body decreases.

More specifically, the time when the process of ink consumption can be detected refers to the time when liquid and gas with different densities co-exist around the vibrating part 61 of the liquid detection device 60 and participate in the vibration. As the ink is gradually consumed, the liquid decreases and the gas increases for the medium participating in the vibration at the periphery of the vibrating portion 61 of the liquid detection device 60 .

For example, when the liquid detection device 60 is arranged horizontally relative to the liquid surface, when tink is smaller than tink-max, the medium participating in the vibration of the liquid detection device 60 includes both ink and gas. Therefore, if the area S of the vibrating portion 61 of the liquid detection device 60 is used to express the state below M'max of Formula 4 with the added mass of ink and gas, then:

M'=M'air+M'ink=ρair*t air/S+ρink*t ink/S (Formula 8). Here, M'air is the inertia of air, and M'ink is the inertia of ink. ρair is the density of air, and ρink is the density of ink. t air is the thickness of the air participating in the vibration, and tink is the thickness of the ink participating in the vibration.

In the medium participating in the vibration on the periphery of the vibrating portion 61 of the liquid detection device 60, gas increases as the liquid decreases, when the liquid detection device 60 is arranged approximately horizontally with respect to the liquid surface of the ink, t air increases, and The tink decreases. As a result, M'var gradually decreases, while the resonance frequency gradually increases. Therefore, the amount of ink remaining in the container main body or the amount of ink consumption can be detected. In addition, the reason why only the density of the liquid is included in Equation 7 is that the density of air is assumed to be negligibly small compared to the density of the liquid.

When the liquid detection device 60 is arranged vertically with respect to the liquid surface of the ink, it can be considered that: in the vibrating part 61 of the liquid detection device 60, the medium participating in the vibration of the liquid detection device 60 is the area of only ink, and the liquid detection device The medium participating in the vibration of 60 is an equivalent circuit (not shown in the figure) in which only gas regions are juxtaposed. If the medium participating in the vibration of the liquid detection device 60 is that the area of only ink is Sink, and the medium participating in the vibration of the liquid detection device 60 is that the area of the region of only gas is S air, then:

1/M'＝1/M'air+1/M'ink＝S air/(ρair*t air)+S ink/(ρink*t ink)

(Formula 9).

In addition, Formula 9 applies to the case where no ink is held in the cavity 43 of the liquid detection device 60 . Regarding the additional inertia in the case of storing ink in the chamber 43 of the liquid detection device 60, it can be calculated by the sum of M' of Formula 9 and M'cav of Formula 7.

Since the vibration of the vibrating part 61 of the liquid detection device 60 changes from the depth of tink-max to the depth d of the ink residue, when the liquid detection device 60 is configured in the degree that the depth of the ink residue is slightly smaller than tink-max When the bottom surface is used, the process of gradually reducing ink cannot be detected. At this time, a change in the amount of ink is detected based on a change in the vibration of the liquid detection device in a slight change in the amount of ink from tink-max to the remaining depth d. In addition, when it is arranged on the side and the diameter of the chamber 43 is small, since the vibration of the liquid detection device 60 passing between the chambers 43 varies slightly, it is difficult to detect the amount of ink passing through the process. Whether the liquid level is higher or lower than chamber 43.

For example, curve Y in FIG. 5A shows the relationship between the ink volume in the container main body and the resonant frequency fs of the ink and the vibrating portion 61 when the vibrating portion 61 forms a small circular vibrating region. It shows a state in which the resonance frequency fs of the ink and the vibrating portion 61 changes rapidly between the ink amount difference Q when the liquid level of the ink in the container main body passes before and after the installation position of the liquid detection device 60 . Thereby, since it is possible to binarize and detect whether or not a predetermined amount of ink remains in the container main body, it is possible to perform highly accurate detection.

The method of using the liquid detection device 60 to detect the presence of liquid can detect the presence or absence of ink by directly contacting the vibrating part 61 with the ink. Compared with the method of calculating the consumption of ink by software, the detection accuracy is high. In addition, the method of using electrodes to detect the presence of ink through conductivity may be affected by the installation position of the electrodes on the container body and the type of ink, but the method of using the liquid detection device 60 to detect the presence of liquid is difficult to be affected by the liquid on the container body. The installation position of the detection device 60 and the influence of the type of ink.

In addition, since both vibration and liquid detection can be performed with a single liquid detection device 60, the number of sensors mounted on the container body can be reduced compared to a method of performing vibration and liquid detection with different sensors. Therefore, the ink cartridge 7 having a liquid amount detection function can be manufactured at low cost. In addition, it is preferable to set the vibration frequency of the piezoelectric layer 47 to an inaudible range, so that the sound generated during the operation of the liquid detection device 60 is quiet.

FIG. 5B shows an example of the relationship between the density of the ink and the resonance frequency fs of the ink and the vibrating portion 61 . Here, "full of ink" and "empty of ink" (or "empty of ink") mean two relative states, not the so-called full state of ink and depleted state of ink. As shown in FIG. 5B, when the ink density is high, the resonance frequency fs decreases due to the large additional inertia. That is, the resonance frequency differs depending on the type of ink. Therefore, by measuring the resonance frequency fs, it is possible to confirm whether or not ink having a different density is mixed when ink is refilled. That is, it is possible to identify the ink cartridges 7 storing inks of different types.

Next, the size and shape of the cavity 43 are set so that liquid remains in the cavity 43 of the liquid detection device 60 even when the liquid in the container body of the ink cartridge 7 is empty, and the condition of the liquid state can be accurately detected at this time. Describe in detail. If the liquid detection device 60 can detect the state of the liquid when the cavity 43 is filled with liquid, it can also detect the state of the liquid when the cavity 43 is not filled with liquid.

The resonance frequency fs is a function of the inertia M. The inertia M is the sum of the inertia Mact of the vibrating portion 61 and the additional inertia M'. Here, the additional inertia M' is related to the state of the liquid. The additional moment of inertia M' is an amount representing an apparent increase in the mass of the vibrating portion 61 by the medium in the vicinity of the vibrating portion 61. That is, the amount of increase in mass of the vibrating portion 61 caused by the vibration of the vibrating portion 61 apparently absorbing the medium (inertia associated with the vibration increases).

Therefore, when M'cav is larger than M'max in Equation 4, apparently the absorbed medium is all the liquid remaining in the cavity 43 . Therefore, it is the same as the state in which the container main body is filled with medium. At this time, since the medium participating in the vibration is smaller than M'max, the change cannot be detected even if the ink is consumed.

On the other hand, when M'cav is less than M'max in Equation 4, the apparently absorbed medium is the residual liquid in the chamber 43 and the gas or vacuum in the container body. At this time, unlike the state where the container body is filled with liquid, M' changes, so the resonance frequency fs also changes. Therefore, the liquid detection device 60 can detect the state of the liquid in the container main body.

That is, in the state where the liquid in the container main body of the ink cartridge 7 is empty, when liquid remains in the chamber 43 of the liquid detection device 60, the condition that the liquid detection device 60 can detect the liquid state correctly is that M'cav ratio M 'max is small. In addition, the condition that the liquid detection device 60 can correctly detect the state of the liquid is M'max>M'cav, regardless of the shape of the cavity 43.

Here, M'cav is the mass inertia of the liquid having a capacity approximately equal to the capacity of the cavity 43 . Therefore, according to the inequality of M'max>M'cav, the condition that the liquid detection device 60 can correctly detect the state of the liquid can be expressed as a condition of the capacity of the cavity 43 . For example, if the radius of the circular cavity 43 is a, and the depth of the cavity 43 is d, then:

M'max>ρ*d/πa ² (Formula 10).

After expanding Equation 10, the following conditions can be obtained:

a/d＞3*π/8 (Formula 11).

Therefore, if it is the liquid detecting device 60 having the cavity 43 whose radius a of the opening 161 and the depth d of the cavity 43 satisfy Formula 11, the liquid in the container main body is in an empty state, and even when liquid remains in the cavity 43, The state of the liquid can also be detected without malfunction.

In addition, Formula 10 and Formula 11 hold true only when the shape of the cavity 43 is circular. When the shape of the cavity 43 is not circular, if the corresponding M'max formula is used to replace πa2 in Formula 10 with its area for calculation, the relationship between the width and length of the cavity 43 and other dimensions and depth can be derived.

In addition, since the additional inertia M' also affects the acoustic impedance characteristic, it can be said that the method of detecting the counter electromotive force generated in the liquid detection device 60 due to the residual vibration can detect at least a change in the acoustic impedance.

6A and 6B show the waveform of the residual vibration (free vibration) of the liquid detection device 60 and the measurement method of the residual vibration after the vibration part 61 is forcibly driven by supplying a drive signal to the liquid detection device 60 . Whether the liquid level is up or down in the installation position of the liquid detection device 60 in the ink cartridge 7 can be detected by the change in frequency or amplitude of the residual vibration after the piezoelectric element of the liquid detection device 60 vibrates. In FIGS. 6A and 6B , the vertical axis represents the voltage of the counter electromotive force generated by the residual vibration of the liquid detection device 60 , and the horizontal axis represents time. The waveform of the analog signal of the voltage is generated by the residual vibration of the liquid detection device 60 as shown in FIGS. 6A and 6B . Next, the analog signal is converted into a digital value corresponding to the frequency of the signal (binarization). In the example shown in FIGS. 6A and 6B , the generation time of four pulses from the fourth pulse to the eighth pulse of the analog signal is measured.

More specifically, after the liquid detection device 60 vibrates, the number of times a preset predetermined reference voltage crosses from the low voltage side to the high voltage side is counted. Then, a digital signal is generated to be at a high level between the count value 4 and the count value 8, and the time from the count value 4 to the count value 8 is measured by a predetermined clock pulse.

FIG. 6A is a waveform when the liquid level is above the installation position level of the liquid detection device 60 . In contrast, FIG. 6B is a waveform when the liquid level is lower than the installation position level of the liquid detection device 60 . Comparing FIG. 6A and FIG. 6B , it is found that the time from count value 4 to count value 8 is longer in FIG. 6A than in FIG. 6B . In other words, the time required from the count value 4 to the count value 8 varies depending on whether there is ink or not at the installation position of the liquid detection device 60 . Using this difference in required time, the consumption state of ink can be detected.

The reason why counting is started from the fourth count value of the analog waveform is to start measurement after the residual vibration (free vibration) of the liquid detection device 60 is stabilized. Counting from the fourth count value is just an example, and counting from any count value may be started. Here, a signal from the fourth count value to the eighth count value is detected, and the time from the fourth count value to the eighth count value is measured by a predetermined clock pulse. Based on this time, the resonance frequency can be obtained. The clock pulse does not necessarily have to measure the time to the eighth pulse, but can also be counted to an arbitrary count value. In FIG. 6A and FIG. 6B, although the time from the fourth count value to the eighth count value is measured, the time in different count value intervals can also be detected according to the circuit structure of the detection frequency.

For example, when the quality of the ink is stable and the fluctuation of the peak amplitude is small, in order to increase the detection speed, the resonance frequency can also be obtained by detecting the time from the fourth count value to the sixth count value. In addition, when the ink quality is unstable and the pulse amplitude fluctuates greatly, the time from the fourth count value to the twelfth count value may be detected in order to accurately detect the residual vibration.

FIG. 7 is a perspective view showing a structure in which the liquid detection device 60 is integrally formed as the mounting module body 100 . The module body 100 is installed at a predetermined position of the container body of the ink cartridge 7 . The module body 100 is configured to detect the consumption state of the liquid in the container body by detecting at least a change in the acoustic impedance of the medium in the container body.

The module body 100 of this embodiment has a container attachment part 101 for attaching the liquid detection device 60 to the container main body. The container mounting part 101 has a substantially rectangular base 102 and a cylindrical part 116 on the base 102 for accommodating the liquid detection device 60 vibrated by a driving signal. In addition, the module body 100 is configured so that the liquid detection device 60 of the module body 100 cannot be touched from the outside when it is mounted on the ink cartridge 7 . Thereby, the liquid detection device 60 can be protected from external contact. In addition, the edge of the front end of the cylindrical portion 116 is rounded so that it can be easily fitted into the hole formed in the ink cartridge 7 when it is attached.

FIG. 8 is an exploded view of the module body 100 shown in FIG. 7 . The module body 100 includes a container mounting portion 101 formed of resin, and a device mounting portion 105 having a disk 110 and a recess 113 (see FIG. 7 ). In addition, the module body 100 has lead wires 104 a and 104 b , a liquid detection device 60 , and a film 108 . The disk 110 is preferably formed of a material that is hard to rust, such as stainless steel or a stainless steel alloy.

The cylindrical part 116 and the base 102 included in the container mounting part 101 form an opening part 114 in the central part so that the lead wires 104a and 104b can be accommodated, and a recessed part 113 is formed around the opening part 114 so that the liquid detection device 60, Membrane 108 and disc 110.

The liquid detection device 60 is bonded to the disk 110 through the film 108, and the disk 110 and the liquid detection device 60 are fixed in the concave portion 113 (container mounting portion 101). Therefore, the lead wires 104a and 104b, the liquid detection device 60, the membrane 108, and the disc 110 are mounted in the container mounting portion 101 as a unit.

The lead wires 104a and 104b are connected to the upper electrode terminal 45 and the lower electrode terminal 44 of the liquid detection device 60 respectively, thereby transmitting a drive signal (drive pulse) to the piezoelectric layer 47, and transmitting the signal of the resonance frequency detected by the liquid detection device 60 to to the recording device, etc.

The liquid detection device 60 temporarily vibrates in accordance with the driving signals transmitted from the lead wires 104a and 104b. In addition, the liquid detection device 60 performs residual vibration after vibration, and generates counter electromotive force by the vibration. At this time, by detecting the vibration period of the counter electromotive force waveform, it is possible to detect the resonance frequency corresponding to the liquid consumption state in the container main body.

Membrane 108 bonds liquid detection device 60 to disk 110, thereby making liquid detection device 60 liquid-tight. The film 108 is preferably formed of polyolefin or the like, and bonded by heat welding. The liquid detection device 60 is planarly bonded and fixed to the disk 110 through the film 108, thereby eliminating the deviation of the bonding position, so that the part other than the vibrating part does not vibrate. Therefore, even if the liquid detection device 60 is bonded to the disk 110, the vibration characteristics of the liquid detection device 60 do not change.

In addition, the disk 110 is circular, and the opening 114 of the base 102 is formed in a cylindrical shape. The liquid detection device 60 and the membrane 108 are formed in a rectangular shape. The lead wires 104 a and 104 b , the liquid detection device 60 , the film 108 , and the disk 110 may be detachable from the base 102 . The base 102 , the lead wires 104 a and 104 b , the liquid detection device 60 , the membrane 108 and the disc 110 are arranged symmetrically with respect to the central axis of the module body 100 . In addition, the centers of the base 102 , the liquid detection device 60 , the membrane 108 , and the disk 110 are arranged substantially on the central axis of the module body 100 .

In addition, the area of the opening 114 of the base 102 is formed to be larger than the area of the vibration region of the liquid detection device 60 . A through hole 112 is formed at a position where the center of the disk 110 faces the vibrating portion of the liquid detection device 60 . As shown in FIGS. 2 to 4 , a cavity 43 is formed in the liquid detection device 60 , and the through hole 112 together with the cavity 43 forms an ink storage portion. In order to reduce the influence of residual ink, the thickness of the disk 110 is preferably smaller than the diameter of the through hole 112 . For example, the depth of the through hole 112 is preferably less than one third of its diameter. The through hole 112 is approximately circular and symmetrical with respect to the central axis of the module body 100 . In addition, the area of the through hole 112 is larger than the opening area of the cavity 43 of the liquid detection device 60 . The edge of the section of the through hole 112 may be tapered or stepped.

The module body 100 is mounted on the side, top or bottom of the container body with the through hole 112 facing the inside of the container body. When the ink is consumed and there is no ink around the liquid detection device 60, the resonant frequency of the liquid detection device 60 changes greatly, so that the liquid level change of the ink can be detected.

9 is a cross-sectional view of the vicinity of the bottom of the container body 7 a when the module body 100 shown in FIG. 7 is attached to the container body 7 a of the ink cartridge 7 . The module body 100 is installed in a through hole formed in the side wall of the container main body 7a. An O-ring 90 is provided on the joint surface between the side wall of the container body 7a and the module body 100 to maintain the liquid-tightness between the module body 100 and the container body 7a. For such sealing with the O-ring 90, the module body 100 is preferably provided with a cylindrical part as shown in FIG.

The top end of the module body 100 is exposed to the ink storage space 7b of the container body 7a, so that the ink in the container body 7a contacts the liquid detection device 60 through the through hole 112 of the disk 110 . The resonant frequency of the residual vibration of the liquid detection device 60 differs depending on whether the vibrating portion of the liquid detection device 60 is surrounded by liquid or gas, so that the module body 100 can be used to detect the consumption state of ink.

Next, a liquid detection device according to another embodiment of the present invention and an ink cartridge (liquid container) equipped with the liquid detection device will be described with reference to the drawings.

10 , 11A and 11B are schematic views of a liquid detection device 260 according to this embodiment. The liquid detection device 260 has a base 240 formed by laminating a vibrating plate 242 on a substrate 241, and the base 240 has first surfaces facing each other. 240a and the second surface 240b. A circular cavity (recess) 243 is formed in the base portion 240 for receiving a medium to be detected, and the cavity 243 is opened on the first surface 240a side, and the bottom surface portion 243a of the cavity 243 is formed so that a vibrating plate can pass through. 242 vibrations. In other words, the portion of the entire vibrating plate 242 that actually vibrates is defined by the cavity 243 . A lower electrode terminal 244 and an upper electrode terminal 245 are formed at both ends of the base 240 on the second surface 240 b side.

On the second surface 240b of the base 240, a lower electrode (first electrode) 246 having a circular main body portion 246a and an extension portion 246b extending from the main body portion 246a to the bottom electrode terminal 244 is formed. direction and is connected to the lower electrode terminal 244 . The center of the circular body portion 246 a of the lower electrode 246 coincides with the center of the cavity 243 .

The circular body portion 246 a of the lower electrode 246 is formed to have a larger diameter than the circular cavity 243 and cover all regions corresponding to the cavity 243 .

Over the lower electrode 246 is laminated a piezoelectric layer 247 having a circular body portion 247a having a smaller diameter than the cavity 243, and an extension portion 247b extending from the body portion 247a across the The position corresponding to the edge of the cavity 243 extends to the outside of the area corresponding to the bottom surface of the cavity 243 .

A circular body portion 249 a of the upper electrode (second electrode) 249 is stacked on the piezoelectric layer 247 . The body portion 249 a of the upper electrode 249 is formed to have a smaller diameter than the body portion 247 a of the piezoelectric layer 247 . In addition, the upper electrode 249 has an extension portion 249b extending from the main body portion 249a, extending over the extension portion 247b of the piezoelectric layer 247 to the outside of a region corresponding to the bottom surface of the cavity 243 . The extension portion 249 b extends beyond the extension portion 247 b of the piezoelectric layer 247 and is connected to the upper electrode terminal 245 .

In this way, the main body portion 247 a of the piezoelectric layer 247 is sandwiched between the main body portion 249 a of the upper electrode 249 and the main body portion 246 a of the lower electrode 246 . Thus, the piezoelectric layer 247 can be efficiently deformed and driven.

As described above, the main body portion 249 a of the upper electrode 249 is formed to have a smaller diameter than the main body portion 247 a of the piezoelectric layer 247 . On the other hand, the main body portion 246 a of the lower electrode 246 covers the entire surface of the main body portion 247 a of the piezoelectric layer 247 . Therefore, the body portion 249 a of the upper electrode 249 determines the range of the portion where the piezoelectric effect is generated in the entire piezoelectric layer 247 .

In addition, the components included in the liquid detection device 260 are preferably integrally formed with each other by sintering. By integrally forming the liquid detection device 260 in this way, the handling of the liquid detection device 260 can be facilitated.

The piezoelectric layer 247 is preferably made of lead zirconate titanate (PZT), lead lanthanum zirconate titanate (PLZT), or a lead-free piezoelectric film that does not use lead. The material of the substrate 241 is preferably zirconia or alumina. In addition, it is preferable to use the same material as the substrate 241 for the vibrating plate 242 . The upper electrode 249 , the lower electrode 246 , the upper electrode terminal 245 , and the lower electrode terminal 244 can be made of conductive materials, such as metals such as gold, silver, copper, platinum, aluminum, and nickel.

As for the main body portion 247 a of the piezoelectric layer 247 , the main body portion 249 a of the upper electrode 249 , and the main body portion 246 a of the lower electrode 246 , their centers coincide with the center of the cavity 243 . In addition, the center of the circular cavity 243 defining the vibrator portion of the vibrating plate 242 is located on the center of the entire liquid detection device 260 .

The vibrator portion of the vibrating plate 242 defined by the cavity 243, the portion corresponding to the cavity 243 of the main body portion 246a of the lower electrode 246, the portions corresponding to the cavity 243 of the main body portion 247a and the extension portion 247b of the piezoelectric layer 247, and the upper portion The main part 249 a of the electrode 249 and the part corresponding to the cavity 243 of the extension part 249 b constitute the vibrating part 261 of the liquid detection device 260 . In addition, the center of the vibrating portion 261 of this liquid detection device 260 coincides with the center of the liquid detection device 260 .

In addition, the main body portion 247a of the piezoelectric layer 247, the main body portion 249a of the upper electrode 249, the main body portion 246a of the lower electrode 246, and the vibrator portion of the vibrating plate 242 (that is, the portion corresponding to the bottom surface portion 243a of the cavity 243) have circular shapes. Therefore, the vibrating part 261 of the liquid detection device 260 has a substantially symmetrical shape with respect to the center of the liquid detection device 260 .

Thus, in the present embodiment, since the entire region corresponding to the cavity 243 is covered with the main body portion 246a of the lower electrode 246, the difference between the deformation mode during the forced vibration and the deformation mode during the free vibration is reduced compared with conventional ones. difference between. In addition, since the vibrating portion 261 of the liquid detection device 260 has a substantially symmetrical shape with respect to the center of the liquid detection device 260 , the rigidity of the vibrating portion 261 is substantially isotropic when viewed from the center.

Therefore, occurrence of unnecessary vibration due to structural asymmetry is suppressed, and output reduction of counter electromotive force due to difference in deformation mode between when forced to vibrate and when vibrating freely is prevented. Thereby, the detection accuracy of the resonance frequency of the residual vibration in the vibrating part 261 of the liquid detection device 260 is improved, and the detection of the residual vibration of the vibrating part 261 is also facilitated.

In addition, since the main body portion 246a of the lower electrode 246 having a diameter larger than that of the cavity 243 covers the entire region corresponding to the cavity 243, it is possible to prevent unnecessary vibration from being generated due to position deviation of the lower electrode 246 during manufacture, thereby A decrease in detection accuracy can be prevented.

In addition, since the vibrating portion 261 of the liquid detection device 260 is in contact with the liquid only within the range where the chamber 243 exists, liquid detection can be performed accurately, whereby the ink level in the ink cartridge 7 can be detected with high precision.

As a modified example of this embodiment, as shown in FIG. 12 , insulating layer 250 may be sandwiched between extension portion 249 b of upper electrode 249 and piezoelectric layer 247 . Due to the existence of the insulating layer 250 , the range of the portion where the piezoelectric effect is generated in the entire piezoelectric layer 247 is circular, thereby improving its symmetry, thereby further suppressing generation of unnecessary vibrations.

Next, a liquid detection device according to another embodiment of the present invention and an ink cartridge (liquid container) equipped with the liquid detection device will be described with reference to the drawings.

13 , FIG. 14A and FIG. 14B are schematic diagrams of a liquid detection device 360 according to this embodiment. The liquid detection device 360 has a base 340 formed by laminating a vibrating plate 342 on a substrate 341, and the base 340 has first surfaces facing each other. 340a and the second surface 340b. A circular cavity (recess) 343 is formed in the base portion 340 for receiving a medium as a detection object, and the cavity 343 is opened on the first surface 340a side, and the bottom surface portion 343a of the cavity 343 is formed so that a vibrating plate can pass through. 342 vibrations. In other words, the portion of the entire vibrating plate 342 that actually vibrates is defined by the cavity 343 . A lower electrode terminal 344 and an upper electrode terminal 345 are formed at both ends of the base 340 on the second surface 340 b side.

On the second surface 340b of the base 340 is formed a lower electrode (first electrode) 346 having a circular main body portion 346a and an extension portion 346b extending from the main body portion 346a to the lower electrode terminal 344. extending in the direction of and connected to the lower electrode terminal 344 . The center of the circular body portion 346 a of the lower electrode 346 coincides with the center of the cavity 343 .

The circular body portion 346 a of the lower electrode 346 is formed to have a larger diameter than the circular cavity 343 and cover all regions corresponding to the cavity 343 .

Over the lower electrode 346 is laminated a piezoelectric layer 347 having a circular body portion 347a and an extension portion 347b, wherein the body portion 347a is formed to be larger in diameter than the cavity 343 so as to cover the entirety of the cavity 343 Corresponding area; the extension portion 347b extends from the main body portion 347a.

On the piezoelectric layer 347, a circular main body portion 349a of an upper electrode (second electrode) 349 is stacked. the interior of the area. In addition, the upper electrode 349 has an extension portion 349b extending from the body portion 349a and extending above the body portion 347a of the piezoelectric layer 347 and the extension portion 347b. The extension portion 349 b extends beyond the extension portion 347 b of the piezoelectric layer 347 and is connected to the upper electrode terminal 345 .

In this way, the main body portion 347 a of the piezoelectric layer 347 has a structure sandwiched between the main body portion 349 a of the upper electrode 349 and the main body portion 346 a of the lower electrode 346 . Thereby, the piezoelectric layer 347 can be efficiently deformed and driven.

As described above, the main body portion 349 a of the upper electrode 349 is formed to have a smaller diameter than the main body portion 347 a of the piezoelectric layer 347 . On the other hand, the main body portion 346 a of the lower electrode 346 covers the entire surface of the main body portion 347 a of the piezoelectric layer 347 . Therefore, the body portion 349a of the upper electrode 349 determines the range of the portion where the piezoelectric effect is generated in the entire piezoelectric layer 347 .

In addition, the components included in the liquid detection device 360 are preferably integrally formed with each other by sintering. By integrally forming the liquid detection device 360 in this way, the handling of the liquid detection device 360 can be facilitated.

The piezoelectric layer 347 is preferably made of lead zirconate titanate (PZT), lead lanthanum zirconate titanate (PLZT), or a lead-free piezoelectric film that does not use lead. The material of the substrate 341 is preferably zirconia or alumina. In addition, it is preferable to use the same material as the substrate 341 for the vibrating plate 342 . The upper electrode 349 , the lower electrode 346 , the upper electrode terminal 345 , and the lower electrode terminal 344 can be made of conductive materials, such as metals such as gold, silver, copper, platinum, aluminum, and nickel.

As for the main body portion 347 a of the piezoelectric layer 347 , the main body portion 349 a of the upper electrode 349 , and the main body portion 346 a of the lower electrode 346 , their centers coincide with the center of the cavity 343 . In addition, the center of the circular cavity 343 defining the vibrator portion of the vibrating plate 342 is located on the center of the entire liquid detection device 360 .

The vibrator portion of the vibrating plate 342 defined by the cavity 343, the portion of the main body portion 346a of the lower electrode 346 corresponding to the cavity 343, the portion of the main body portion 347a of the piezoelectric layer 347 corresponding to the cavity 343, and the main body portion of the upper electrode 349 349 a and the part corresponding to the cavity 343 of the extension part 349 b constitute the vibrating part 361 of the liquid detection device 360 . In addition, the center of the vibrating portion 361 of this liquid detection device 360 coincides with the center of the liquid detection device 360 .

In addition, the main body portion 347a of the piezoelectric layer 347, the main body portion 349a of the upper electrode 349, the main body portion 346a of the lower electrode 346, and the vibrator portion of the vibrating plate 342 (ie, the portion corresponding to the bottom surface portion 343a of the cavity 343) have circular shapes. Therefore, the vibrating part 361 of the liquid detection device 360 has a substantially symmetrical shape with respect to the center of the liquid detection device 360 .

In this way, in this embodiment, since the entire area corresponding to the cavity 343 is covered with the main body portion 346a of the lower electrode 346 and the main body portion 347a of the piezoelectric layer 347, the deformation during forced vibration is reduced compared with conventional ones. mode and the deformation mode in free vibration. In addition, since the vibration part 361 of the liquid detection device 360 has a substantially symmetrical shape with respect to the center of the liquid detection device 360, the rigidity of the vibration part 361 is substantially isotropic when viewed from the center.

Therefore, occurrence of unnecessary vibration due to structural asymmetry is suppressed, and output reduction of counter electromotive force due to difference in deformation mode between when forced to vibrate and when vibrating freely is prevented. Accordingly, the detection accuracy of the resonance frequency of the residual vibration in the vibrating portion 361 of the liquid detection device 360 is improved, and the detection of the residual vibration of the vibrating portion 361 is also facilitated.

In addition, since the main body portion 346a of the lower electrode 346 having a diameter larger than that of the cavity 343 covers the entire region corresponding to the cavity 343, it is possible to prevent unnecessary vibration from being generated due to position deviation of the lower electrode 346 during manufacture, thereby A decrease in detection accuracy can be prevented.

In addition, since the vibrating portion 361 of the liquid detection device 360 is in contact with the liquid only within the range where the cavity 343 exists, liquid detection can be performed accurately, whereby the ink level in the ink cartridge 7 can be detected with high precision.

As a modified example of this embodiment, as shown in FIG. 15 , insulating layer 350 may be sandwiched between extension portion 349 b of upper electrode 349 and piezoelectric layer 347 . Due to the existence of the insulating layer 350 , the range of the portion where the piezoelectric effect is generated in the entire piezoelectric layer 347 is circular, thereby improving its symmetry, thereby further suppressing generation of unnecessary vibrations.

Next, a liquid detection device according to another embodiment of the present invention and an ink cartridge (liquid container) equipped with the liquid detection device will be described with reference to the drawings.

16 , 17A, and 17B are schematic diagrams of a liquid detection device 460 according to this embodiment. The liquid detection device 460 has a base 440 formed by laminating a vibration plate 442 on a substrate 441, and the base 440 has first surfaces facing each other. 440a and the second surface 440b. A circular cavity (recess) 443 is formed in the base 440 for receiving a medium as a detection object, and the cavity 443 is opened on the first surface 440a side, and the bottom surface 443a of the cavity 443 is formed so that a vibrating plate can pass through it. 442 vibrations. In other words, the portion of the entire vibrating plate 442 that actually vibrates is defined by the cavity 443 . A lower electrode terminal 444 and an upper electrode terminal 445 are formed at both ends of the base 440 on the second surface 440 b side.

On the second surface 440b of the base 440 is formed a lower electrode (first electrode) 446 having a circular main body portion 446a and an extension portion 446b extending from the main body portion 446a to the lower electrode terminal 444. extending in the direction of and connected to the lower electrode terminal 444 . The center of the circular body portion 446 a of the lower electrode 446 coincides with the center of the cavity 443 .

The circular body portion 446 a of the lower electrode 446 is formed to have a smaller diameter than the circular cavity 443 so as to be disposed inside a region corresponding to the cavity 443 . The diameter of the main body portion 446 a of the lower electrode 446 is preferably at least 75% of the diameter of the cavity 443 .

A circular body portion 447a of the piezoelectric layer 447 is stacked on the body portion 446a of the lower electrode 446 and formed to have a smaller diameter than the body portion 446a of the lower electrode 446 . An extension portion 447 b extends from the main body portion 447 a of the piezoelectric layer 447 , and the extension portion 447 b of the piezoelectric layer 447 extends all the way to the outside of the region corresponding to the cavity 443 .

On the main body 447a of the piezoelectric layer 447, a circular main body 449a of the upper electrode (second electrode) 449 is stacked, and the main body 449a of the upper electrode 449 is formed to have a smaller diameter than the main body 447a of the piezoelectric layer 447. . In addition, the upper electrode 449 has an extension portion 449b extending from the main portion 449a and extending over the main portion 447a and the extension portion 447b of the piezoelectric layer 447 . The extension portion 449 b extends beyond the extension portion 447 b of the piezoelectric layer 447 and is connected to the upper electrode terminal 445 .

In this way, the main body portion 447 a of the piezoelectric layer 447 is sandwiched between the main body portion 449 a of the upper electrode 449 and the main body portion 446 a of the lower electrode 446 . Thus, the piezoelectric layer 447 can be efficiently deformed and driven.

As described above, the main body portion 449 a of the upper electrode 449 is formed to have a smaller diameter than the main body portion 447 a of the piezoelectric layer 447 . On the other hand, the main body portion 446 a of the lower electrode 446 covers the entire surface of the main body portion 447 a of the piezoelectric layer 447 . Therefore, the body portion 449 a of the upper electrode 449 determines the range of the portion where the piezoelectric effect is generated in the entire piezoelectric layer 447 .

In addition, the components included in the liquid detection device 460 are preferably integrally formed with each other by sintering. By integrally forming the liquid detection device 460 in this way, the handling of the liquid detection device 460 can be facilitated.

The piezoelectric layer 447 is preferably made of lead zirconate titanate (PZT), lead lanthanum zirconate titanate (PLZT), or a lead-free piezoelectric film that does not use lead. The material of the substrate 441 is preferably zirconia or alumina. In addition, it is preferable to use the same material as the substrate 441 for the vibrating plate 442 . The upper electrode 449 , the lower electrode 446 , the upper electrode terminal 445 , and the lower electrode terminal 444 can be made of conductive materials, such as metals such as gold, silver, copper, platinum, aluminum, and nickel.

As for the body portion 447 a of the piezoelectric layer 447 , the body portion 449 a of the upper electrode 449 , and the body portion 446 a of the lower electrode 446 , their centers coincide with the center of the cavity 443 . Furthermore, the center of the circular cavity 443 defining the vibrator portion of the vibrating plate 442 is located on the center of the entire liquid detection device 460 .

The vibrator portion of the vibrating plate 442 defined by the cavity 443, the portion corresponding to the cavity 443 of the main body portion 446a and the extension portion 446b of the lower electrode 446, and the portion corresponding to the cavity 443 of the main body portion 447a and the extension portion 447b of the piezoelectric layer 447. part, and the part corresponding to the cavity 443 of the main part 449 a and the extension part 449 b of the upper electrode 449 constitutes the vibrating part 461 of the liquid detection device 460 . In addition, the center of the vibrating portion 461 of this liquid detection device 460 coincides with the center of the liquid detection device 460 .

In addition, the main body portion 447a of the piezoelectric layer 447, the main body portion 449a of the upper electrode 449, the main body portion 446a of the lower electrode 446, and the vibrator portion of the vibrating plate 442 (ie, the portion corresponding to the bottom surface portion 443a of the cavity 443) have circular shapes. Therefore, the vibration part 461 of the liquid detection device 460 has a substantially symmetrical shape with respect to the center of the liquid detection device 460 .

Thus, in the present embodiment, since the diameter of the main body portion 446a of the lower electrode 446 is formed larger than that of the main body portion 447a of the piezoelectric layer 447, and the main body portion 446a of the lower electrode 446 covers a large area with the The area corresponding to the cavity 443 thus reduces the area of the thin portion not covered by the main body portion 446a of the lower electrode 446 . Therefore, it is possible to suppress excitation of unnecessary higher-order vibration modes other than the necessary vibration frequency to be detected during the free vibration of the forcibly deformed vibrating portion. In addition, during free vibration, only the thin portion deforms greatly and the deformation amount of the piezoelectric layer 447 is small, thereby preventing the phenomenon that the output of counter electromotive force becomes small, thereby reducing the force vibration during forced vibration compared with conventional ones. The difference between the deformation mode and the deformation mode in free vibration.

Thus, according to the present embodiment, occurrence of unnecessary vibration due to structural asymmetry is suppressed, and counter electromotive force due to difference in deformation mode between the time of forced vibration and the time of free vibration is prevented. The output is reduced. Thereby, the detection accuracy of the resonance frequency of the residual vibration in the vibrating part 461 of the liquid detection device 460 is improved, and the detection of the residual vibration of the vibrating part 461 is also facilitated.

In addition, since the diameter of the main body portion 447a of the piezoelectric layer 447 laminated on the main body portion 446a of the lower electrode 446 is formed smaller than the diameter of the main body portion 446a of the lower electrode 446, and the diameter of the main body portion 447a of the piezoelectric layer 447 is formed The diameter of the main body portion 449a of the upper electrode 449 is formed smaller than that of the main body portion 447a of the piezoelectric layer 447, so in the manufacturing process, the diameter of the part formed later (for example, the main body portion 447a of the lower electrode 447) is smaller than that of the part formed earlier. (For example, the main body portion 446a of the lower electrode 446) has a small diameter. Therefore, since the next part can be formed while confirming the position of the part formed earlier up to the end, positioning at the time of lamination can be performed with high precision.

In addition, since the diameter of the main body portion 446a of the lower electrode 446 is formed smaller than that of the main body portion 447a of the piezoelectric layer 447, the edge of the main body portion 446a of the lower electrode 446 can be adjacent to the edge of the bottom surface portion 443a of the cavity 443. Accordingly, the area of the thin portion not covered by the main body portion 446a of the lower electrode 446 can be reduced.

In addition, since the vibrating portion 461 of the liquid detection device 460 is in contact with the liquid only within the range where the chamber 443 exists, liquid detection can be performed accurately, whereby the ink level in the ink cartridge 7 can be detected with high precision.

Next, a liquid detection device according to another embodiment of the present invention and an ink cartridge (liquid container) equipped with the liquid detection device will be described with reference to the drawings.

18 , 19A, and 19B are schematic diagrams of a liquid detection device 560 according to this embodiment. The liquid detection device 560 has a base 540 formed by laminating a vibrating plate 542 on a substrate 541, and the base 540 has first surfaces facing each other. 540a and the second surface 540b. A circular cavity (recess) 543 is formed in the base 540 for receiving a medium to be detected. The cavity 543 is opened on the first surface 540 a side, and the bottom surface 543 a of the cavity 543 is formed so that the vibrating plate 542 can pass through. vibration. In other words, the portion of the entire vibrating plate 542 that actually vibrates is defined by the cavity 543 . A lower electrode terminal 544 and an upper electrode terminal 545 are formed at both ends of the base 540 on the second surface 540 b side.

On the second surface 540b of the base 540, a lower electrode (first electrode) 546 having a circular main body portion 546a and an extension portion 546b extending from the main body portion 546a to the lower electrode terminal 544 is formed. extending in the direction of and connected to the lower electrode terminal 544 . The center of the circular body portion 546 a of the lower electrode 546 coincides with the center of the cavity 543 .

The diameter of the circular body portion 546 a of the lower electrode 546 is formed larger than that of the circular cavity 543 so as to cover the entire area corresponding to the cavity 543 .

Over the lower electrode 546 is laminated a piezoelectric layer 547 having a circular body portion 547a and an extension portion 547b, wherein the diameter of the body portion 547a is formed larger than that of the cavity 543 so as to cover the entire and The cavity 543 corresponds to the area where the extension portion 547b extends from the main body portion 547a.

On the piezoelectric layer 547, an annular body portion 549a of an upper electrode (second electrode) 549 is laminated. The interior of the area corresponding to the cavity 543 . In addition, the upper electrode 549 has an extension portion 549 b that extends from the body portion 549 a and extends over the body portion 547 a of the piezoelectric layer 547 and the extension portion 547 b. The extension portion 549 b extends beyond the extension portion 547 b of the piezoelectric layer 547 and is connected to the upper electrode terminal 545 .

In this way, the main body portion 547 a of the piezoelectric layer 547 is sandwiched between the main body portion 549 a of the upper electrode 549 and the main body portion 546 a of the lower electrode 546 . Thus, the piezoelectric layer 547 can be efficiently deformed and driven.

As described above, the diameter of the main body portion 549 a of the upper electrode 549 is formed smaller than that of the main body portion 547 a of the piezoelectric layer 547 . On the other hand, the main body portion 546 a of the lower electrode 546 covers the entire surface of the main body portion 547 a of the piezoelectric layer 547 . Therefore, the main body portion 549a of the upper electrode 549 determines the range of the portion where the piezoelectric effect is generated in the entire piezoelectric layer 547 .

In addition, the components included in the liquid detection device 560 are preferably integrally formed with each other by sintering. By integrally forming the liquid detection device 560 in this way, the handling of the liquid detection device 560 can be facilitated.

The piezoelectric layer 547 is preferably made of lead zirconate titanate (PZT), lead lanthanum zirconate titanate (PLZT), or a lead-free piezoelectric film that does not use lead. The material of the substrate 541 is preferably zirconia or alumina. In addition, it is preferable to use the same material as the substrate 541 for the vibrating plate 542 . The upper electrode 549 , the lower electrode 546 , the upper electrode terminal 545 , and the lower electrode terminal 544 can be made of conductive materials, such as metals such as gold, silver, copper, platinum, aluminum, and nickel.

As for the main body portion 547 a of the piezoelectric layer 547 , the main body portion 549 a of the upper electrode 549 , and the main body portion 546 a of the lower electrode 546 , their centers coincide with the center of the cavity 543 . In addition, the center of the circular cavity 543 defining the vibrator portion of the vibrating plate 542 is located on the center of the entire liquid detection device 560 .

The vibrator portion of the vibrating plate 542 defined by the cavity 543, the portion corresponding to the cavity 543 of the main body portion 546a of the lower electrode 546, the portion corresponding to the cavity 543 of the main body portion 547a of the piezoelectric layer 547, and the main body of the upper electrode 549 The portion 549 a and the extended portion 549 b corresponding to the cavity 543 constitute the vibrating portion 561 of the liquid detection device 560 . In addition, the center of the vibrating portion 561 of this liquid detection device 560 coincides with the center of the liquid detection device 560 .

In addition, the main body portion 547a of the piezoelectric layer 547, the main body portion 549a of the upper electrode 549, the main body portion 546a of the lower electrode 546, and the vibrator portion of the vibrating plate 542 (ie, the portion corresponding to the bottom surface portion 543a of the cavity 543) have circular shapes. Therefore, the vibrating part 561 of the liquid detection device 560 has a substantially symmetrical shape with respect to the center of the liquid detection device 560 .

In addition, since the vibrator 561 of the liquid detection device 560 applies a voltage to the piezoelectric layer 547 through the upper electrode 549 and the lower electrode 546 , it protrudes and deforms in the direction opposite to the cavity 543 .

In this way, in this embodiment, since the entire area corresponding to the cavity 543 is covered with the main body portion 546a of the lower electrode 546 and the main body portion 547a of the piezoelectric layer 547, the deformation during forced vibration is reduced compared with conventional ones. mode and the deformation mode in free vibration. In addition, since the vibrating portion 561 of the liquid detection device 560 has a substantially symmetrical shape with respect to the center of the liquid detection device 560 , the rigidity of the vibrating portion 561 is substantially isotropic when viewed from the center.

In addition, since the entire region corresponding to the cavity 543 is covered with the main body portion 546a of the lower electrode 546 having a diameter larger than that of the cavity 543, generation of unnecessary vibration due to positional deviation of the lower electrode 546 at the time of manufacture can be prevented, thereby enabling A reduction in detection accuracy is prevented.

In addition, since the main body portion 549a of the upper electrode 549 is formed in an annular shape, as shown in FIG. A portion of the extension portion 549 b of the upper electrode 549 inside the region corresponding to the cavity 543 becomes smaller, thereby improving the symmetry of the upper electrode 549 constituting a portion of the vibrating portion 561 .

Therefore, occurrence of unnecessary vibration due to structural asymmetry is suppressed, and output reduction of counter electromotive force due to difference in deformation mode between when forced to vibrate and when vibrating freely is prevented. Accordingly, the detection accuracy of the resonance frequency of the residual vibration in the vibrating portion 561 of the liquid detection device 560 is improved, and detection of the residual vibration of the vibrating portion 561 is also facilitated.

In addition, since the vibrating portion 561 of the liquid detection device 560 is in contact with the liquid only within the range where the cavity 543 exists, liquid detection can be performed accurately, whereby the ink level in the ink cartridge 7 can be detected with high precision.

Next, a liquid detection device according to another embodiment of the present invention and an ink cartridge (liquid container) equipped with the liquid detection device will be described with reference to the drawings.

20 , 21A, and 21B are schematic diagrams of a liquid detection device 660 according to this embodiment. The liquid detection device 660 has a base 640 formed by laminating a vibration plate 642 on a substrate 641. The base 640 has first surfaces facing each other. 640a and the second surface 640b. A circular cavity (recess) 643 is formed in the base 640 for receiving a medium to be detected. The cavity 643 is opened on the first surface 640 a side, and the bottom surface 643 a of the cavity 643 is formed so that the vibrating plate 642 can pass through. vibration. In other words, the portion of the entire vibrating plate 642 that actually vibrates is defined by the cavity 643 . A lower electrode terminal 644 and an upper electrode terminal 645 are formed at both ends of the base 640 on the second surface 640 b side.

On the second surface 640b of the base 640, a lower electrode (first electrode) 646 having a circular main body portion 646a and an extension portion 646b extending from the main body portion 646a to the lower electrode terminal 644 is formed. extending in the direction of and connected to the lower electrode terminal 644 . The center of the circular body portion 646 a of the lower electrode 646 coincides with the center of the cavity 643 .

The circular body portion 646 a of the lower electrode 646 is formed to have a diameter smaller than that of the circular cavity 643 and is disposed inside a region corresponding to the cavity 643 .

A circular piezoelectric layer 647 having a diameter larger than that of the main body portion 646a of the lower electrode 646 is stacked on the lower electrode 646. As can be seen from FIG. . In other words, the piezoelectric layer 647 does not have a portion extending across a position corresponding to the edge 643 a of the cavity 643 at all.

An auxiliary electrode 648 whose end is connected to the upper electrode terminal 645 is formed on the second surface 640 b side of the base 640 . The auxiliary electrode 648 crosses the position corresponding to the edge 643 a of the cavity 643 from the outside of the area corresponding to the cavity 643 , and extends to the inside of the area corresponding to the cavity 643 . Inside the region corresponding to the cavity 643 , a part of the auxiliary electrode 648 supports a part of the piezoelectric layer 647 from the second surface 640 b side of the substrate 640 . The auxiliary electrode 648 preferably has the same material and thickness as the lower electrode 646 . In this way, since the auxiliary electrode 648 supports a part of the piezoelectric layer 647 from the second surface 640 b side of the substrate 640 , there is no step difference in the piezoelectric layer 647 , and a decrease in mechanical strength can be prevented.

On the piezoelectric layer 647, a circular body portion 649a of an upper electrode (second electrode) 649 formed to have a diameter smaller than that of the piezoelectric layer 647 and smaller than that of the body portion 646a of the lower electrode 646 is laminated. Large diameter. In addition, the upper electrode 649 has an extension portion 649 b extending from the main body portion 649 a and connected to the auxiliary electrode 648 . As can be seen from FIG. 21B , the position P where the connection between the extension portion 649 b of the upper electrode 649 and the auxiliary electrode 648 starts is within the range of the region corresponding to the cavity 643 .

As can be seen from FIG. 20 , the upper electrode 649 is electrically connected to the upper electrode terminal 645 via the auxiliary electrode 648 . Connecting the upper electrode 649 to the upper electrode terminal 645 via the auxiliary electrode 648 in this way allows both the upper electrode 649 and the auxiliary electrode 648 to absorb the difference in the total thickness of the piezoelectric layer 647 and the lower electrode 646 . Therefore, it is possible to prevent a large step difference from being generated on the upper electrode 649 and resulting in a decrease in mechanical strength.

As can be seen from FIG. 20 , the main body portion 649 a of the upper electrode 649 is formed in a circular shape, and its center coincides with the center of the cavity 643 . The main body portion 649 a of the upper electrode 649 is formed to have a smaller diameter than both the piezoelectric layer 647 and the cavity 643 .

In this way, the piezoelectric layer 647 has a structure sandwiched between the main body portion 649 a of the upper electrode 649 and the main body portion 646 a of the lower electrode 646 . Thus, the piezoelectric layer 647 can be efficiently deformed and driven.

In addition, in the main body portion 646a of the lower electrode 646 and the main body portion 649a of the upper electrode 649 electrically connected to the piezoelectric layer 647, the diameter of the main body portion 646a of the lower electrode 646 is formed smaller. Therefore, the body portion 646a of the lower electrode 646 determines the range of the portion of the piezoelectric layer 647 where the piezoelectric effect is generated.

In addition, the components included in the liquid detection device 660 are preferably integrally formed with each other by sintering. By integrally forming the liquid detection device 660 in this way, the handling of the liquid detection device 660 can be facilitated.

The piezoelectric layer 647 is preferably made of lead zirconate titanate (PZT), lead lanthanum zirconate titanate (PLZT), or a lead-free piezoelectric film that does not use lead. The material of the substrate 641 is preferably zirconia or alumina. In addition, it is preferable to use the same material as the substrate 641 for the vibrating plate 642 . The upper electrode 649 , the lower electrode 646 , the upper electrode terminal 645 , and the lower electrode terminal 644 can be made of conductive materials, such as metals such as gold, silver, copper, platinum, aluminum, and nickel.

The vibrating portion of the vibrating plate 642 defined by the cavity 643, the portion corresponding to the cavity 643 of the main body portion 646a and the extension portion 646b of the lower electrode 646, the piezoelectric layer 647, and the main body portion 649a and the extension portion 649b of the upper electrode 649 A portion corresponding to the cavity 643 constitutes a vibrating portion 661 of the liquid detection device 660 . In addition, the center of the vibrating portion 661 of this liquid detection device 660 coincides with the center of the liquid detection device 660 .

In addition, the piezoelectric layer 647, the main body portion 649a of the upper electrode 649, the main body portion 646a of the lower electrode 646, and the vibrator portion of the vibrating plate 642 (ie, the portion corresponding to the bottom surface portion 643a of the cavity 643) have circular shapes, Furthermore, since the entire piezoelectric layer 647 is arranged inside the region corresponding to the cavity 643 , the vibrating portion 661 of the liquid detection device 660 has a substantially symmetrical shape with respect to the center of the liquid detection device 660 .

Thus, in this embodiment, since the vibration part 661 of the liquid detection device 660 has a symmetrical shape with respect to the center of the liquid detection device 660, the rigidity of the vibration part 661 is isotropic when viewed from the center. In particular, since the piezoelectric layer 647 that greatly affects the rigidity of the vibrating portion 661 is formed in a circular shape, the isotropy of the rigidity of the vibrating portion 661 is greatly improved. Therefore, it is possible to suppress the occurrence of unnecessary vibration due to the asymmetry of the structure, thereby improving the detection accuracy of the resonance frequency of the residual vibration of the vibration portion 661 of the liquid detection device 660 .

In addition, the entire piezoelectric layer 647 that is hard and fragile is arranged inside the region corresponding to the cavity 643 so that the piezoelectric layer 647 does not exist at a position corresponding to the edge 643 a of the cavity 643 . Therefore, there is no problem of cracking of the piezoelectric film that occurs at positions corresponding to the edges of the cavity in conventional liquid detection devices.

In addition, since the range where the vibrating portion 661 is in contact with the liquid is limited to the range where the chamber 643 exists, liquid detection can be performed accurately, whereby the ink level in the ink cartridge 7 can be detected with high precision.

In addition, as a modified example of the above-mentioned embodiment, as shown in FIG. 22 , FIG. 23A and FIG. 23B , except for the extension portion 646 b of the lower electrode 646 extending in opposite directions on the first straight line passing through the center of the cavity 643 and In addition to the extension portion 649b of the upper electrode 649, a second straight line extending from the main body portion 646a of the lower electrode 646 to opposite directions may be provided on a second straight line passing through the center of the cavity 643 and perpendicular to the first straight line. For extension 646c.

In addition, the pair of extension portions 646 c may not be formed continuously from the main body portion 646 a of the lower electrode 646 , but may be formed separately from the main body portion 646 a of the lower electrode 646 .

In this way, the pair of extended portions 646c that do not actually function as electrodes are arranged along a straight line passing through the center of the cavity 643, and are aligned with the extending direction of the extended portion 646b of the lower electrode 646 and the extended portion 649b of the upper electrode 649. vertical, thereby increasing the symmetry of the vibrating portion 661 compared to the embodiments shown in FIGS. 20 , 21A and 21B. That is, in the embodiment shown in Fig. 20, Fig. 21A and Fig. 21B, the shape of the vibrating part 661 is quadratic symmetry, and in the modified example shown in Fig. 22, Fig. 23A and Fig. 23B, the shape of the vibrating part 661 is Four times symmetrical. In this way, by improving the symmetry of the shape of the vibrating portion 661, the occurrence of unnecessary vibration can be further reduced.

As mentioned above, although the preferable embodiment of this invention was described in some degree of detail, it is obvious that many changes and deformation|transformation are possible. Therefore, it should be understood that the present invention may be practiced otherwise than as specifically described herein without departing from the scope and spirit of the present invention.

Claims (35)

1. A liquid detection device, characterized in that, comprising: a base having a first surface and a second surface opposite to each other, and having a recess for receiving a medium to be detected, the recess being formed to open on the first surface side, and a bottom surface of the recess is formed to vibrate; The first electrode is formed on the second surface side of the base and has a body portion, wherein the body portion is formed in a size larger than the bottom surface of the concave portion so as to cover almost the entire The area corresponding to the bottom surface of the concave part, and the main body part includes a notch part formed by indenting inward from a position corresponding to the edge of the bottom surface of the concave part; a piezoelectric layer having a main body portion formed in a size smaller than the bottom surface of the concave portion and entirely contained within a region corresponding to the bottom surface of the concave portion, wherein all of the piezoelectric layer The main body portion is substantially entirely laminated on the first electrode except for a portion corresponding to the cutout portion of the first electrode; an auxiliary electrode formed on the second surface side of the base, extending from the outside of the region corresponding to the bottom surface of the concave portion to the inside of the region corresponding to the bottom surface of the concave portion, and a part of which is located in the the inside of the cutout portion of the first electrode, and supports a part of the piezoelectric layer from the second surface side; and a second electrode having a main body portion laminated on the piezoelectric layer and an extension portion extending from the main body portion at a region corresponding to a bottom surface of the recess. Internally connected to the auxiliary electrode. 2. The liquid detection device according to claim 1, wherein the piezoelectric layer has a protruding portion extending from the bottom surface of the piezoelectric layer within the range of a region corresponding to the bottom surface of the concave portion. A body portion protrudes, and the protruding portion is supported by the auxiliary electrode. 3. The liquid detection device according to claim 1 or 2, wherein the body portion of the second electrode is formed in a smaller size than the body portion of the piezoelectric layer. 4. The liquid detection device according to any one of claims 1 to 3, wherein the main part of the piezoelectric layer and the main part of the second electrode have at least one common axis of symmetry roughly symmetrical shape. 5. The liquid detection device according to claim 4, wherein the main part of the piezoelectric layer and the main part of the second electrode are both circular and arranged concentrically with each other. 6. A liquid detection device, characterized in that, comprising: a base having a first surface and a second surface opposite to each other, and having a recess for receiving a medium to be detected, the recess being formed to open on the first surface side, and a bottom surface of the recess is formed to vibrate; a first electrode formed on the side of the second surface of the base with a size larger than the bottom surface of the concave portion so as to cover the entire area corresponding to the bottom surface of the concave portion; a piezoelectric layer having a body portion formed in a size smaller than a bottom surface of the concave portion and laminated on the first electrode inside a region corresponding to the bottom surface of the concave portion; and A second electrode having a body portion laminated on the body portion of the piezoelectric layer. 7. The liquid detection device according to claim 6, wherein the piezoelectric layer further has an extension portion extending from the main body portion of the piezoelectric layer and over the contact with the concave portion. The position corresponding to the edge extends to the outside of the area corresponding to the bottom surface of the recess. 8. The liquid detection device according to claim 6 or 7, wherein the body portion of the second electrode is formed in a smaller size than the body portion of the piezoelectric layer. 9. The liquid detection device according to claim 7 or 8, wherein the second electrode further has an extension portion extending from the main body portion of the second electrode, extending through the pressurized The extension portion of the electrical layer is above and extends to the outside of a region corresponding to the bottom surface of the recess. 10. The liquid detection device according to any one of claims 6 to 9, wherein the main portion of the piezoelectric layer and the main portion of the second electrode are arranged to have at least one common axis of symmetry roughly symmetrical shape. 11. The liquid detection device according to claim 10, wherein the concave portion, the main body portion of the piezoelectric layer, and the main body portion of the second electrode are all circular and are aligned with each other. Configure with heart. 12. The liquid detection device according to any one of claims 9 to 11, further comprising an insulating layer interposed between the extension portion of the second electrode and the piezoelectric layer. 13. A liquid detection device, characterized in that it comprises: a base having a first surface and a second surface opposite to each other, and having a recess for receiving a medium to be detected, the recess being formed to open on the first surface side, and a bottom surface of the recess is formed to vibrate; a first electrode formed on the side of the second surface of the base with a size larger than the bottom surface of the concave portion so as to cover the entire area corresponding to the bottom surface of the concave portion; a piezoelectric layer having a main body portion formed in a size larger than the bottom surface of the concave portion and laminated on the first electrode covering the entire area corresponding to the bottom surface of the concave portion; and A second electrode having a main body portion formed in a size smaller than the bottom surface of the concave portion and laminated on the piezoelectric layer inside a region corresponding to the bottom surface of the concave portion. on the main body. 14. The liquid detection device according to claim 13, wherein the body portion of the piezoelectric layer is formed in a smaller size than the body portion of the first electrode. 15. The liquid detection device according to claim 13 or 14, wherein, The piezoelectric layer also has an extension extending from the body portion of the piezoelectric layer; The second electrode also has an extension portion extending from the main body portion of the second electrode and extending through the main body portion of the piezoelectric layer and an upper portion of the extension portion. 16. The liquid detection device according to any one of claims 13 to 15, wherein the main part of the piezoelectric layer and the main part of the second electrode have at least one common axis of symmetry roughly symmetrical shape. 17. The liquid detection device according to claim 16, wherein the concave portion and the main body portion of the second electrode are both circular and arranged concentrically with each other. 18. The liquid detection device according to any one of claims 15 to 17, further comprising an insulating layer interposed between the extension portion of the second electrode and the piezoelectric layer. 19. A liquid detection device, characterized in that it comprises: a base having a first surface and a second surface opposite to each other, and having a recess for receiving a medium to be detected, the recess being formed to open on the first surface side, and a bottom surface of the recess is formed to vibrate; a first electrode having a main body portion formed on the second surface side of the base with a size smaller than the bottom surface of the concave portion and arranged in a region corresponding to the bottom surface of the concave portion internal; a piezoelectric layer having a body portion formed in a smaller size than that of the first electrode and laminated on the body portion of the first electrode; and A second electrode having a body portion formed with a smaller size than the body portion of the piezoelectric layer and laminated on the body portion of the piezoelectric layer. 20. The liquid detection device as claimed in claim 19, wherein, The first electrode further has an extension portion extending from the body portion of the first electrode and extending to the outside of a region corresponding to the bottom surface of the recess; The piezoelectric layer further has an extension portion extending from the main body portion of the piezoelectric layer and extending to the outside of a region corresponding to the bottom surface of the concave portion; The second electrode also has an extension portion extending from the main body portion of the second electrode and extending through the main body portion of the piezoelectric layer and an upper portion of the extension portion. 21. The liquid detection device according to claim 19 or 20, wherein the recess and the main body of the first electrode are circular and arranged concentrically with each other; The diameter of the main body part is more than 75% of the diameter of the recess. 22. A liquid detection device, characterized in that it comprises: a base having a first surface and a second surface opposite to each other, and having a recess for receiving a medium to be detected, the recess being formed to open on the first surface side, and a bottom surface of the recess is formed to vibrate; a first electrode formed on the side of the second surface of the base with a size larger than the bottom surface of the concave portion so as to cover the entire area corresponding to the bottom surface of the concave portion; a piezoelectric layer having a main body portion formed in a size larger than the bottom surface of the concave portion and laminated on the first electrode covering the entire area corresponding to the bottom surface of the concave portion; and A second electrode having a ring-shaped main body portion formed with an outer ring diameter smaller than the bottom surface of the concave portion, and laminated on the pressure plate inside a region corresponding to the bottom surface of the concave portion. on the body portion of the electrical layer. 23. The liquid detection device according to claim 22, wherein the body portion of the piezoelectric layer is formed in a smaller size than the body portion of the first electrode. 24. The liquid detection device according to claim 22 or 23, wherein, The piezoelectric layer also has an extension extending from the body portion of the piezoelectric layer; The second electrode also has an extension portion extending from the main body portion of the second electrode and extending through the main body portion of the piezoelectric layer and an upper portion of the extension portion. 25. The liquid detection device according to any one of claims 22 to 24, wherein said main portion of said piezoelectric layer and said main portion of said second electrode are arranged with at least one common axis of symmetry roughly symmetrical shape. 26. The liquid detection device as claimed in claim 25, wherein, the concave portion is circular; the main body portion of the second electrode is circular; the concave portion and the main body of the second electrode The sections are arranged concentrically with each other. 27. A liquid detection device, characterized in that it comprises: a base having a first surface and a second surface opposite to each other, and having a recess for receiving a medium to be detected, the recess being formed to open on the first surface side, and a bottom surface of the recess is formed to vibrate; The first electrode is formed on the second surface side of the base and has a body portion and an extension portion, wherein the body portion is formed in a size smaller than the bottom surface of the concave portion and configured inside a region corresponding to the bottom surface of the concave portion, the extension portion extending from the main body portion and extending to the outside of the region corresponding to the bottom surface of the concave portion; a piezoelectric layer formed with a size smaller than the bottom surface of the concave portion, laminated on the first electrode, and entirely arranged inside a region corresponding to the bottom surface of the concave portion; an auxiliary electrode formed on the second surface side of the base, extending from the outside of the region corresponding to the bottom surface of the concave portion to the inside of the region corresponding to the bottom surface of the concave portion, and a part of which extends from the supporting a portion of the piezoelectric layer on one side of the second face; and A second electrode having a main body portion laminated on the piezoelectric layer and an extension portion extending from the main body portion inside a region corresponding to a bottom surface of the concave portion connected to the auxiliary electrode. 28. The liquid detection device as claimed in claim 27, wherein the size of the body portion of the first electrode is smaller than the size of the piezoelectric layer; the size of the body portion of the second electrode is smaller than The body portion of the first electrode has a large size. 29. The liquid detection device according to claim 27 or 28, wherein the size of the body portion of the second electrode is smaller than the size of the piezoelectric layer. 30. The liquid detection device according to any one of claims 27 to 29, wherein, the extension portion of the first electrode and the extension portion of the second electrode extend in opposite directions to each other on a first straight line passing through the center of the recess; The first electrode also has a pair of extending portions extending from the main body portion of the first electrode on a second straight line passing through the center of the concave portion and perpendicular to the first straight line. extend in opposite directions. 31. The liquid detection device of claim 30, wherein the pair of extension portions are separated from the main body portion of the first electrode. 32. The liquid detection device according to any one of claims 27 to 31, wherein said body portion of said first electrode, said body portion of said piezoelectric layer and said body portion of said second electrode The body parts are all circular and arranged concentrically with each other. 33. A liquid container, comprising: a container body for storing liquids; and The liquid detection device according to any one of claims 1 to 32, Wherein, the concave portion of the liquid detection device is exposed into the liquid storage space of the container body. 34. The liquid container according to claim 33, wherein a liquid for a liquid ejection device is stored in the container body. 35. The liquid container according to claim 34, wherein the liquid ejecting device is an inkjet type recording device; ink is stored in the container main body.

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