JP2008137159A - Liquid detection device, ink cartridge and printing device - Google Patents

Abstract

A liquid detection device, an ink cartridge, and a printing device capable of accurately detecting that the remaining amount of liquid is almost zero and the viscosity or concentration of the liquid are provided.
The liquid container is provided with a storage part 71 for storing liquid, a discharge port, and a flow path 73 for guiding the liquid from the storage part 71 to the discharge port. A liquid detection device for detection, in which a concave portion 811 is formed at a central portion, and the central portion is a thin portion 812 that functions as a vibrator that vibrates in a thickness-slip mode or a thickness mode, and the concave portion 811 side of the thin portion 812 is Piezoelectric body 81 provided so as to be exposed to flow path 73, resonance means for resonating thin portion 812, detection means for detecting the resonance frequency and / or insertion loss at resonance of thin portion 812, and detection results thereof And a liquid condition acquisition means for determining the viscosity or concentration of the liquid.
[Selection] Figure 7

Description

  The present invention relates to a liquid detection device, an ink cartridge, and a printing device.

As a printing apparatus that performs printing on a recording medium such as paper, a printer that employs an inkjet method is known. Such a printer generally performs printing by supplying ink from an ink cartridge mounted on a carriage to an ink jet head and ejecting the ink from the ink jet head onto a recording medium as droplets.
In such a printing apparatus, the ink cartridge can be attached to and detached from the carriage, and when the remaining amount of ink in the ink cartridge becomes almost zero or a predetermined amount or less, the ink cartridge is replaced with a new one. It can be replaced with an ink cartridge.

Such an ink cartridge has a storage part in which ink is stored, a discharge port for supplying ink in the storage part to the droplet discharge head, and a flow path that connects the storage part and the discharge port. The remaining amount of ink in the storage part is detected by a liquid detection device.
As a liquid detection apparatus, for example, as disclosed in Patent Document 1, a liquid detection apparatus having a diaphragm that forms a part of the inner wall surface of a reservoir and a piezoelectric body provided on the diaphragm is known. It has been. In such a liquid detection device, the vibration plate is vibrated by the piezoelectric body, and the remaining amount of ink in the reservoir can be detected based on the change in the resonance frequency. Then, by displaying such a detection result of the remaining ink amount on a display or the like, it is possible to notify the user of the replacement timing of the ink cartridge.

However, in the liquid detection device according to Patent Document 1, when the diaphragm is vibrated by the piezoelectric body, the vibration leaks. For this reason, it cannot be accurately detected whether or not the remaining amount of ink in the reservoir is zero.
Further, the liquid detection device detects the remaining amount of ink, and cannot detect the viscosity or density of the ink. For this reason, in order to detect the viscosity and density of the ink, it is necessary to separately install the detection device, the structure becomes complicated, a wide installation space is required, and the entire device becomes large.

JP 2001-146024 A

  An object of the present invention is to provide a liquid detection device, an ink cartridge, and a printing device that can accurately detect that the remaining amount of liquid is almost zero and the viscosity or concentration of the liquid.

Such an object is achieved by the present invention described below.
A liquid detection apparatus according to the present invention includes a storage unit that stores a liquid, a discharge port for discharging the liquid from the storage unit, and a flow path that guides the liquid from the storage unit to the discharge port. A liquid detection device that is used in a container and detects the presence or absence of liquid in the reservoir,
A recess is formed in the center, the center is a thin part that functions as a vibrator, and the piezoelectric body provided so that the recess side of the thin part is exposed to the flow path;
Resonating means for resonating the thin portion of the piezoelectric body;
Detecting means for detecting a resonance frequency and / or insertion loss at the time of resonance of the thin-walled portion of the piezoelectric body;
A discriminating means for discriminating whether or not the remaining amount of liquid in the reservoir is substantially zero based on the detection result of the detecting means;
Liquid condition acquisition means for determining the viscosity or concentration of the liquid in the reservoir based on the detection result of the detection means;
The vibration mode of the thin portion of the piezoelectric body is a thickness-slip mode or a thickness mode.

Thereby, it is possible to accurately detect that the remaining amount of the liquid is almost zero and the viscosity or concentration of the liquid.
That is, since a concave portion is formed in the central portion of the piezoelectric body, and the thin portion at the central portion functions as a vibrator, vibration leakage from the thin portion causes a thick wall around the periphery (peripheral portion). In addition to being suppressed (or prevented) by the part, the vibration mode is set to the thickness-slip mode or the thickness mode, and by these synergistic effects, the vibration of the thin part can be reliably confined in the concave part (almost thin wall) Only the portion can be vibrated), and leakage of vibration can be prevented. This makes it possible to accurately detect the resonance frequency of the thin-walled portion of the piezoelectric body and the insertion loss at the time of resonance, thereby accurately indicating that the remaining amount of liquid is almost zero and the viscosity or concentration of the liquid. Can be detected.

  In addition, the liquid is in contact with the thin portion of the piezoelectric body until the remaining amount of the liquid becomes almost zero, and when the remaining amount of the liquid becomes almost zero, the liquid in contact with the thin portion becomes the thin portion. Although the piezoelectric body is provided so that the concave portion side of the thin portion is exposed to the flow path, when the remaining amount of the liquid becomes almost zero, the liquid level of the liquid in the concave portion first decreases, The liquid that is in contact with the thin wall portion is reliably separated from the thin wall portion. When the liquid is separated from the thin wall portion, the resonance frequency of the thin wall portion of the piezoelectric body and the insertion loss at the time of resonance change significantly, thereby accurately and reliably confirming that the remaining amount of liquid is almost zero. Can be detected.

In the liquid detection device according to the aspect of the invention, it is preferable that the concave portion side of the thin portion of the piezoelectric body faces a lower side in the vertical direction, and a part of the flow path is configured by the concave portion.
Thereby, it can be detected more accurately and reliably that the remaining amount of liquid is almost zero.
In the liquid detection device according to the aspect of the invention, it is preferable that the concave portion side of the thin portion of the piezoelectric body faces a substantially horizontal direction, and a part of the flow path is configured by the concave portion.
Thereby, the discharge property of the bubble from a flow path (recessed part) can be improved.

In the liquid detection device according to the aspect of the invention, it is preferable that the flow path is formed in a substantially U-shape, and the concave portion is located in the folded portion.
Thereby, when the remaining amount of the liquid becomes almost zero, the liquid is accumulated below the thin portion of the piezoelectric body, and the liquid can be prevented from coming into contact with the thin portion. It is possible to more accurately and reliably detect that the remaining amount of the battery is almost zero. Further, the liquid flows smoothly through the flow path.

In the liquid detection device according to the aspect of the invention, the resonance unit includes an oscillation circuit including a thin portion of the piezoelectric body, and the oscillation circuit is operated to resonate the thin portion of the piezoelectric body. It is preferable.
Thereby, the thin part of a piezoelectric body can be resonated easily and reliably.
In the liquid detection apparatus of the present invention, it is preferable that the piezoelectric body is made of quartz.
Since quartz has a low temperature dependency, it is not necessary to provide a temperature correction film or the like, and the resonance frequency of the thin portion of the piezoelectric body and the insertion loss at the time of resonance can be detected with high accuracy.
In addition, for example, since an off-the-shelf AT-cut quartz resonator already has a recess, the use of this makes it possible to simplify the manufacture of the liquid detection device.

In the liquid detection device of the present invention, the input electrode and the output electrode provided on the surface opposite to the concave portion of the thin portion of the piezoelectric body, and the surface on the concave portion side of the thin portion of the piezoelectric body. A common electrode provided in
By operating the resonance means and the detection means, the voltage between the output electrode and the common electrode is detected while applying a voltage between the input voltage and the common electrode, and based on the detection result. It is preferable to detect the resonance frequency of the thin portion of the piezoelectric body.
Accordingly, the resonance frequency of the thin portion of the piezoelectric body and the insertion loss at the time of resonance can be detected more accurately with a relatively simple configuration.

In the liquid detection apparatus of the present invention, it is preferable that the liquid has conductivity and also serves as the common electrode.
Thereby, a structure can be simplified more.
In the liquid detection device of the present invention, when the determination unit determines whether or not the remaining amount of liquid in the storage unit is substantially zero, and as a result, it is determined that the remaining amount of liquid in the storage unit is not zero. It is preferable that the liquid condition obtaining unit is configured to obtain the viscosity or concentration of the liquid in the storage unit.
Thereby, it is possible to prevent a useless process for obtaining the viscosity or concentration of the liquid even though the remaining amount of the liquid is almost zero.

In the liquid detection device according to the aspect of the invention, the determination unit may be configured to determine whether or not the remaining amount of liquid in the storage unit is substantially zero based on a detection result of the insertion loss by the detection unit. preferable.
Thereby, it can be detected more accurately and reliably that the remaining amount of liquid is almost zero.

In the liquid detection apparatus according to the aspect of the invention, it is preferable that the liquid condition acquisition unit is configured to obtain the viscosity or concentration of the liquid in the storage unit based on the detection result of the resonance frequency by the detection unit.
Thereby, the viscosity or concentration of the liquid can be detected more accurately.
In the liquid detection device according to the aspect of the invention, it is preferable that the liquid container is an ink cartridge in which ink is stored in the storage unit.
Thereby, it is possible to accurately detect that the remaining amount of ink in the ink cartridge is almost zero and the viscosity or concentration of the ink.

The ink cartridge of the present invention is an ink cartridge that is used in a state of being loaded in a printing apparatus that performs printing on a recording medium, and is filled with ink.
A reservoir for storing ink as a liquid;
A discharge port for discharging ink from the reservoir;
A flow path for guiding the ink from the reservoir to the outlet;
A concave portion is formed in the central portion, the central portion is a thin portion that functions as a vibrator, and the piezoelectric portion is provided so that the concave portion side of the thin portion is exposed to the flow path,
The vibration mode of the thin portion of the piezoelectric body is a thickness sliding mode or a thickness mode,
In a state of being loaded in the printing apparatus, the thin portion of the piezoelectric body is resonated, and the resonance frequency and / or insertion loss at the time of resonance of the thin portion of the piezoelectric body is detected, and the storage is performed based on the detection result. It is characterized in that it is possible to determine whether or not the remaining amount of liquid in the section is substantially zero and to determine the viscosity or concentration of the liquid in the storage section.
Thereby, it is possible to accurately detect that the remaining amount of ink in the ink cartridge is almost zero and the viscosity or concentration of the ink.

The printing apparatus of the present invention is a printing apparatus that performs printing on a recording medium using the ink in a state where an ink cartridge filled with ink is loaded,
The liquid detection device according to the present invention is provided, and the liquid container is an ink cartridge in which ink is stored in the storage unit.
Thereby, it is possible to accurately detect that the remaining amount of ink in the ink cartridge is almost zero and the viscosity or concentration of the ink.

Hereinafter, a liquid detection device, an ink cartridge, and a printing device of the present invention will be described in detail based on a preferred embodiment shown in the accompanying drawings.
<First Embodiment>
FIG. 1 is a perspective view showing a first embodiment of a printing apparatus provided with the liquid detection device of the present invention, FIG. 2 is a perspective view of a carriage provided in the printing apparatus shown in FIG. 1, and FIG. 4 is a side view of the carriage shown in FIG. 4, FIG. 5 is a plan view of the carriage shown in FIG. 2, FIG. 5 is a perspective view showing an ink cartridge loaded in the printing apparatus (carriage) shown in FIG. FIG. 7 is a cross-sectional view (partially enlarged view of FIG. 6) showing the sensor and its peripheral part of the liquid detection device provided in the printing apparatus shown in FIG. 1, and FIG. FIG. 9 is a block diagram showing a main circuit portion of the liquid detection device provided in the printing apparatus shown in FIG. 1. FIG. 9 is a plan view showing a sensor of the liquid detection device provided in the printing apparatus shown in FIG.
In the following description, the vertical direction in FIGS. 6 and 7 is the vertical direction. The corresponding direction is the same in other drawings.

First, the overall configuration of the printing apparatus 100 will be briefly described.
A printing apparatus 100 shown in FIG. 1 is a printer that employs an ink jet method, and is loaded with an ink cartridge (liquid container) 1, and recording of paper or the like using ink (liquid) from the ink cartridge 1. Printing on the medium P is performed.
As shown in FIG. 1, the printing apparatus 100 includes a carriage (loading unit) 101 in which the ink cartridge 1 is detachably loaded. The carriage 101 is supported by a guide shaft 102 so as to be movable in the longitudinal direction. In addition, a driving force is received from the carriage motor 104 via the belt 103. Thereby, the carriage 101 moves along the guide shaft 102 by the operation of the carriage motor 104.

An ink jet head 106 that receives ink supplied from the ink cartridge 1 and discharges ink as droplets toward the recording medium P is provided below the carriage 101.
In such a printing apparatus 100, the carriage 101 reciprocates in a direction perpendicular to the moving direction of the recording medium P along the guide shaft 102 while a pair of paper feed rollers (not shown) conveys the recording medium P. At this time, ink is ejected as droplets from the inkjet head 106 onto the recording medium P in accordance with image information from a host computer (not shown), and printing is performed on the recording medium P.

  As shown in FIG. 2, the carriage 101 provided in such a printing apparatus 100 has a substantially box shape that opens upward, and four ink cartridges 1 that are flat are arranged in the thickness direction. It comes to be loaded with. In the present embodiment, the four ink cartridges 1 are filled with magenta, cyan, yellow, and black ink in order from the right side to the left side in FIG.

Grooves 31 and 32 are formed outside the carriage 101 (on the right side in FIG. 3). The grooves 31 and 32 are formed along the direction in which the four ink cartridges 1 are arranged.
The above-described guide shaft 102 is inserted into the groove 31. Further, a guide portion (not shown) formed so as to protrude in parallel with the guide shaft 102 is inserted into the groove 32 in the vicinity of the guide shaft 102. As a result, the carriage 101 can be moved along the guide shaft 102 while keeping its posture constant.

  In addition, a plurality of ribs 33 and 34 protrude from the inside of the carriage 101 having a substantially box shape. The plurality of ribs 33 are separated from each other by a separation distance similar to the thickness of each of the flat ink cartridges 1. Then, like the plurality of ribs 33, the plurality of ribs 34 are spaced apart from each other at intervals similar to the thickness of each ink cartridge 1 so as to form a pair with the plurality of ribs 33. The corresponding ink cartridge 1 is loaded between the plurality of ribs 33 and 34. Thereby, the movement of the ink cartridge 1 in the thickness direction can be regulated by the ribs 33 and 34 to position each ink cartridge 1. Further, the ink cartridge 1 can be easily attached and detached along the ribs 33 and 34.

  A hollow needle 36 for supplying ink to the inkjet head 106 protrudes from the bottom of the carriage 101 upward. When the ink cartridge 1 is loaded on the carriage 101, the hollow needle 36 engages with the discharge port 72 of the ink cartridge 1, and ink is transferred from the ink cartridge 1 to the inkjet head 106 via the hollow needle 36 and a flow path (not shown). Supplied.

In addition, concave portions 37 and 38 that are engaged with engagement pieces 24 of the ink cartridge 1 described later when the ink cartridge 1 is loaded are formed inside the carriage 101. As a result, the ink cartridge 1 can be fixed at a normal position with respect to the carriage 101 together with the ribs 33 and 34 described above.
Further, a concave portion 39 that engages with a guide portion 27 of the ink cartridge 1 described later is formed in the lower portion (bottom portion) of the carriage 101, and an engagement pin 40 made of an elastic material protrudes. It is provided as follows. Thereby, the lower part of the ink cartridge 1 can be reliably positioned with respect to the carriage 101 at a regular position.
A terminal 41 that comes into contact with a terminal 62 of the ink cartridge 1 to be described later is provided at the lower part inside the carriage 101. This terminal 41 is electrically connected to a later-described main circuit 112 and control unit 105 (see FIG. 9) provided in the main body of the printing apparatus 100.

Next, the ink cartridge 1 loaded in the carriage 101 will be described.
The ink cartridge 1 shown in FIG. 5 has a cartridge body 2, a sensor (liquid detection element) 8 installed in the cartridge body 2, and a circuit board (electrode part) 6 electrically connected to the sensor 8. ing.

The cartridge body 2 has a flat outer shape, and is made of, for example, a resin material.
A plate-like engagement piece 24 that can be elastically deformed is cantilevered on the outer wall surface of the cartridge body 2 (upper part of the edge 25) (see FIG. 5B). The engaging piece 24 has a first convex portion 241 and two second convex portions 242 formed on the surface thereof.

  The first convex portion 241 engages with the concave portion 38 of the carriage 101 described above in a state where the ink cartridge 1 is loaded in the carriage 101 (printing apparatus 100) (hereinafter simply referred to as “loaded state”) (see FIG. 3). Further, each of the second convex portions 242 engages with the concave portion 37 of the carriage 101 described above in a loaded state (see FIG. 3). Such engagement can prevent the ink cartridge 1 from being unintentionally detached from the carriage 101.

In addition, a protruding guide portion 27 is formed on the outer wall surface of the cartridge body 2 (lower portion of the edge portion 25). The guide portion 27 engages with the aforementioned concave portion (guide groove) 39 of the carriage 101 in the loaded state (see FIG. 3). Thereby, the ink cartridge 1 is positioned.
A concave portion 28 is formed in the upper portion of the edge portion 26 opposite to the edge portion 25 of the cartridge body 2. The recess 28 is formed in a size that allows the flatness of the thumb to enter.

  In addition, a board installation portion 29 on which the circuit board 6 is installed is formed to protrude below the edge portion 26 of the cartridge body 2. In the loaded state, the substrate placement portion 29 has its upper surface 291 engaged with an engagement pin 40 provided on the carriage 101 and made of an elastic material (see FIG. 3). By being in such a loaded state, it is possible to prevent the ink cartridge 1 from being unintentionally detached from the carriage 101. Further, the ink cartridge 1 is reliably positioned with respect to the carriage 101.

Further, the cartridge body 2 is formed with a hollow portion (lumen portion). As shown in FIG. 6, a storage portion 71 for storing ink and a discharge for discharging ink from the storage portion 71 are provided. An outlet 72 and a flow path 73 that guides ink from the storage portion 71 to the discharge port 72 are provided.
As shown in FIG. 6, the flow path 73 is formed near the bottom surface 711 of the storage portion 71 of the bottom portion 20 of the cartridge body 2. One end side (the left side in FIG. 6) of the flow path 73 communicates with the reservoir 71, and the other end side (the right side in FIG. 6) can communicate with the discharge port 72 via a valve mechanism 23 described later. ing. The flow path 73 has a portion extending in the left-right direction in FIG. 6 along the bottom surface 711, and a portion between the portion and the storage portion 71 forms a bottom wall 712. A sensor 8 is provided on the bottom wall 712 so as to be exposed to the flow path 73. That is, the sensor 8 constitutes a part of the bottom wall 712. The sensor 8 will be described in detail later.

On the right side of the lower surface 21 of the cartridge main body 2, a convex portion 22 protruding downward is formed (see FIG. 6). A concave portion 221 is formed in the convex portion 22, and a discharge port 72 is opened in the concave portion 221 (downward).
Further, the ink cartridge 1 is provided with a valve mechanism 23 that opens and closes the discharge port 72. The valve mechanism 23 includes a valve body 231, a seal member 233 that engages and seals the valve body 231 when the ink cartridge 1 is not loaded in the carriage 101, and biases the valve body 231 toward the seal member 233. And a coil spring 232 to be configured.

  The seal member 233 has a ring shape, and the inner space forms the above-described recess 221. The seal member 233 is made of an elastic material. Although it does not specifically limit as this elastic material, For example, natural rubber, isoprene rubber, butadiene rubber, styrene-butadiene rubber, nitrile rubber, chloroprene rubber, butyl rubber, acrylic rubber, ethylene-propylene rubber, hydrin rubber, urethane rubber, silicone rubber Various rubber materials such as fluoro rubber can be used.

The valve body 231 is movably installed so as to approach or separate from the discharge port 72. The valve body 231 is in close contact with the seal member 233 by the urging force of the coil spring 232 when the ink cartridge 1 is not loaded in the main body (carriage 101) of the printing apparatus 100 (non-loaded state). Thereby, it is possible to prevent the ink from flowing out from the discharge port 72 to an unintentional portion. In addition, the constituent material of the valve body 231 is not particularly limited. For example, various metal materials, various plastics, and the like can be used alone or in combination.
In the loaded state, the hollow needle 36 protruding from the carriage 101 of the printing apparatus 100 presses the valve body 231 against the biasing force of the coil spring 232 and opens the discharge port 72. As a result, ink is supplied to the inkjet head 106 through the hole 361 formed in the hollow needle 36.

  The circuit board 6 has a plurality of terminals 62 electrically connected to the sensor 8 described above. The plurality of terminals 62 are arranged in a staggered pattern as shown in FIG. Each terminal 62 contacts the terminal 41 of the carriage 101 described above in a loaded state (see FIG. 3). Thereby, the sensor 8 and the main circuit 112 are electrically connected in the loaded state, and the signal from the sensor 8 is transmitted to the main circuit 112, or the signal from the main circuit 112 is transmitted to the sensor 8. Can do. Here, each terminal 62 is integrated by a terminal integration part (not shown) provided on the side opposite to the terminal 62 of the circuit board 6, and is insulated by covering a conductor with an unillustrated cable (insulating film such as a resin film). The sensor 8 is electrically connected to the sensor 8 through wiring.

Next, a sensor (liquid detection element) 8 and a liquid detection device including the sensor 8 will be described.
As shown in FIGS. 7 and 8, the sensor 8 has a piezoelectric body 81. The piezoelectric body 81 has a plate shape, and a concave portion 811 is formed in the central portion thereof. The central portion is a thin portion 812 that functions as a vibrator. The piezoelectric body 81 is installed (fixed) in a recess provided in the bottom wall 712. The piezoelectric body 81 is located above the flow path 73 (upward in the vertical direction), and the concave portion 811 side of the thin portion 812 is exposed to the flow path 73. That is, the concave portion 811 side of the thin-walled portion 812 of the piezoelectric body 81 faces the lower side (vertical lower side), and the concave portion 811 constitutes a part of the flow path 73.

  The dimensions of the piezoelectric body 81 are not particularly limited. For example, when the shape of the piezoelectric body 81 in a plan view is substantially a square as shown in the illustrated example, the length of one side is about 1 to 5 mm, for example, The thickness of the thick part 813 can be, for example, about 50 to 150 μm, and the thickness of the thin part 812 can be, for example, about 5 to 50 μm. For example, when the shape of the thin portion 812 in a plan view is substantially circular, the diameter can be set to, for example, about 0.5 to 2 mm.

Needless to say, the recess 811 does not have to be located at the complete center position of the piezoelectric body 81 and may be slightly shifted. Further, the shape of the thin portion 812 is not limited to a circle, and there is no problem even if it is a polygon such as an ellipse or a rectangle.
Further, a convex portion 201 is formed (provided) below the concave portion 811 of the piezoelectric body 81 (downward in the vertical direction) on the inner wall surface defining the flow path 73 in the bottom portion 20 of the cartridge body 2. . That is, of the flow path 73, the flow path 73 disposed below the concave portion 811 of the piezoelectric body 81 is formed in a substantially U shape, and the concave portion 811 of the piezoelectric body 81 is formed in the folded portion 731. positioned.

Further, an annular sealing member 51 is provided between the thick portion 813 and the bottom wall 712 of the piezoelectric body 81, and the sealing member 51 provides a space between the thick portion 813 and the bottom wall 712. Is hermetically sealed (sealed).
The ink stored in the storage portion 71 flows in the flow path 73 from the left side in FIG. 7 to the right side through the concave portion 811 of the piezoelectric body 81.

In addition, an electrode (first electrode) 82 and an electrode (second electrode) 83 that are spaced apart from each other are provided on the upper surface (opposite the concave portion 811) of the thin portion 812 of the piezoelectric body 81. In the present embodiment, the electrode 82 is used (functions) as an input electrode (drive electrode), and the electrode 83 is used as an output electrode (detection electrode).
A terminal 821 that extends to the left end of the piezoelectric body 81 in FIG. 7 is connected to the electrode 82. The electrode 83 is connected to a terminal 831 extending to the right end of the piezoelectric body 81 in FIG. In the present embodiment, the electrode 82 and the terminal 821, and the electrode 83 and the terminal 831 are integrally formed, respectively.

Each of these terminals 821 and 831 is connected to a predetermined terminal 62 of the circuit board 6 described above via a wiring (not shown). Accordingly, the electrodes 82 and 83 are electrically connected to the main circuit 112 in a state where the ink cartridge 1 is loaded on the carriage 101 (loaded state).
As a constituent material of the electrodes 82 and 83, the kind is not particularly limited as long as it is an electrode material, and various known electrode materials can be used. For example, as the constituent materials of the electrodes 82 and 83, metal materials such as Pd, Pt, Au, W, Ta, Mo, Al, Cr, Ti, Cu or alloys containing them, ITO, FTO, ATO, SnO, respectively. Conductive oxides such as ₂ , carbon materials such as carbon black, carbon nanotubes, fullerenes, polyacetylene, polypyrrole, polythiophene such as PEDOT (poly-ethylenedioxythiophene), polyaniline, poly (p-phenylene), poly (p-phenylene vinylene) ), Conductive polymer materials such as polyfluorene, polycarbazole, polysilane or their derivatives, etc., usually doped with polymers such as iron chloride, iodine, strong acid, organic acid, polystyrene sulfonic acid, etc. Use as given It is done. Further, one or more of these can be used in combination.

An electrode (third electrode) 84 is provided on the lower surface (recessed portion 811 side) of the thin portion 812 of the piezoelectric body 81. In the present embodiment, the electrode 84 is used (functions) as a common electrode for the electrodes 82 and 83, that is, as a common counter electrode for the electrodes 82 and 83.
As the constituent material of the electrode 84, for example, the same material as that of the electrodes 82 and 83 can be used. It is preferable to provide a predetermined protective film on the surface and coat the surface with the protective film. For example, when Pt, Au, W, Mo, Ti or the like is used as the constituent material of the electrode 84, it is not necessary to provide a protective film, and when using Al, Ta or the like, it is preferable to provide a protective film. . In the case of Al, for example, a protective film such as SiO ₂ or Al ₂ O ₃ is provided, and in the case of Ta, a protective film such as Ta ₂ O ₅ is provided.

  In the present embodiment, the thin portion 812 of the piezoelectric body 81 is configured to vibrate in the thickness slip mode (the vibration mode of the thin portion 812 of the piezoelectric body 81 is the thickness slip mode). That is, the piezoelectric body 81 is polarized in a direction parallel to the plate surface. In such a piezoelectric body 81, when a voltage is applied between the electrode 82 and the electrode 84, both surfaces of the thin portion 812 are deformed so as to be shifted in opposite directions. That is, when an AC voltage or a pulse voltage is applied between the electrode 82 and the electrode 84, the thin portion 812 vibrates in the thickness shear mode.

  And the voltage between the electrode 83 and the electrode 84 when the thin part 812 of the piezoelectric body 81 is resonating (vibrating at the resonance frequency) is detected, and based on this detection result, the thin part 812 The resonance frequency can be obtained (detected). Further, based on the value (magnitude) of the voltage applied between the electrode 82 and the electrode 84 when the thin portion 812 is resonating and the value of the voltage generated between the electrode 83 and the electrode 84. The insertion loss (insertion loss at resonance) can be obtained (detected).

The vibration mode of the thin portion 812 of the piezoelectric body 81 may be a thickness mode. In this case, the piezoelectric body 81 is polarized in the thickness direction.
In the present embodiment, the piezoelectric body 81 is made of quartz. Since an off-the-shelf AT-cut quartz crystal resonator already has a recess, the use of this as the recess 811 can simplify the manufacture of the ink cartridge 1 (ink detection mechanism). In addition, since the temperature dependency of quartz is small, it is not necessary to provide a temperature correction film or the like, and the resonance frequency of the thin portion 812 of the piezoelectric body 81 and the insertion loss at the time of resonance can be accurately detected.

In addition, the piezoelectric body 81 is not limited to quartz (AT-cut quartz resonator), for example, PZT (PbZr _y Ti _1-y O ₃ ), SBT (SrBi ₂ Ta ₂ O ₉ ), and further to these, Ferroelectric materials such as those added with metals such as niobium, nickel, and magnesium can be used. More specifically, examples of the constituent material of the piezoelectric body 81 include lead titanate (PbTiO ₃ ), lead zirconate titanate (Pb (Zr, Ti) O ₃ ), zirconate (PbZrO ₃ ), and titanate. Lead lanthanum ((Pb, La), TiO ₃ ), lead lanthanum zirconate titanate ((Pb, La) (Zr, Ti) O ₃ ), lead magnesium titanate zirconate titanate (Pb (Zr, Ti) (Mg) , Nb) O ₃ ), lead zinc niobate lead titanate (PZNT), barium titanate (BaTiO ₃ ) (BTO), lithium tantalate (LiTaO ₃ ) (LT), lithium niobate (LiNbO ₃ ) (LN) ZnO, AlN, or the like can be used.

When a material other than crystal is used as the piezoelectric body 81, for example, a temperature correction film is provided, or the accuracy can be improved by performing temperature correction when obtaining the resonance frequency and the insertion loss at the time of resonance. .
In the liquid detection device, the presence or absence of ink (liquid) in the storage unit 71 (whether or not the remaining amount is almost zero), that is, the end of the ink in the storage unit 71 (the ink in the storage unit 71 has been used up). And a device for detecting (obtaining) at least one of the viscosity and concentration in the storage unit 71, and includes the sensor 8 described above. The liquid detection device includes the thin portion 812 of the sensor 8 and the main circuit 112, and includes an oscillation circuit (oscillator) 111 that is a resonance unit that resonates (oscillates) the thin portion 812, and a first measurement circuit ( Detection means) 113, second measurement circuit (detection means) 114, control section (control means) 105, display section 107 serving as display means (notification means) for displaying (notifying) various information, and storage. Part (storage means) 108. The main circuit 112, the first measurement circuit 113, the second measurement circuit 114, the control unit 105, the display unit 107, and the storage unit 108 are each provided in the main body of the printing apparatus 100. Note that the control unit 105, the display unit 107, and the storage unit 108 are not the units dedicated to the liquid detection device, but are the units of the printing apparatus 100 as a whole.

First, the principle for detecting the presence or absence of ink in the reservoir 71 and the viscosity or concentration will be described.
The resonance frequency of the thin portion 812 of the sensor 8 changes depending on whether or not ink (liquid) is in contact with the thin portion 812 of the sensor 8 and also changes according to the viscosity and concentration of the ink.
Further, the insertion loss (loss) at the time of resonance of the thin portion 812 of the sensor 8 changes depending on whether or not the ink is in contact with the thin portion 812 of the sensor 8, and also changes depending on the viscosity and concentration of the ink. To do.

That is, when the ink is not in contact with the thin portion 812 of the sensor 8, the resonance frequency is higher and the insertion loss at the time of resonance is smaller than when the ink is in contact.
On the other hand, when the remaining amount of ink in the storage unit 71 is almost zero, the ink is not in contact with the thin portion 812 of the sensor 8 and the remaining amount of ink in the storage unit 71 is not zero. The ink is in contact with the thin portion 812 of the sensor 8.

Therefore, when the remaining amount of ink in the storage unit 71 is almost zero, the resonance frequency is high and the insertion loss at the time of resonance is small compared to the case where it is not zero.
Also, the lower the ink viscosity, the higher the resonance frequency and the smaller the insertion loss at resonance.
Similarly, the lower the ink concentration, the higher the resonance frequency and the smaller the insertion loss at resonance.

Under the control of the control unit 105, the liquid detection device detects the presence / absence of ink in the storage unit 71 and at least one of the viscosity and concentration of the ink in the storage unit 71 using the above relationship.
Here, the detection of whether or not the remaining amount of ink in the storage unit 71 is substantially zero may be performed based on the resonance frequency of the thin portion 812 of the sensor 8, or at the time of resonance of the thin portion 812 of the sensor 8. May be performed based on the insertion loss. Further, the viscosity and concentration of the ink in the storage unit 71 may be detected based on the resonance frequency of the thin portion 812 of the sensor 8, and based on the insertion loss at the time of resonance of the thin portion 812 of the sensor 8. You may go.

However, the insertion loss at the time of resonance of the thin portion 812 of the sensor 8 varies greatly depending on whether or not the remaining amount of ink in the storage portion 71 is substantially zero as compared with the resonance frequency, and thus is based on the insertion loss at the time of resonance. Thus, it is preferable to determine whether or not the remaining amount of ink is substantially zero.
Further, the resonance frequency of the thin portion 812 of the sensor 8 varies greatly according to the viscosity and concentration of the ink as compared with the insertion loss at the time of resonance. Therefore, the viscosity and concentration of the ink are obtained based on the resonance frequency. Is preferred.

  When ink detection (liquid detection) is performed, first, it is determined whether or not the remaining amount of ink in the storage unit 71 is substantially zero, and as a result, when it is determined that the remaining amount of ink is zero, It is preferable that the process for obtaining the viscosity and density of the ink is not executed, and the process for obtaining the viscosity and density of the ink is executed only when it is determined that the remaining amount of ink is not zero. . Thereby, useless processing can be omitted.

  A threshold value used when determining whether or not the remaining amount of ink is substantially zero based on the resonance frequency, and is used when determining whether or not the remaining amount of ink is approximately zero based on the insertion loss during resonance. Calibration formula for calculating viscosity and density of ink from threshold, resonance frequency and calibration curve for table, calibration formula for calculating viscosity and density of ink from insertion loss at resonance, calibration curve for table, etc. Necessary information is experimentally obtained in advance, stored in the storage unit 108, and read out and used by the control unit 105 when necessary.

  Since the ink viscosity detection method and the ink concentration detection method are substantially the same, in the following description, the case where the ink concentration is detected will be described as a typical example. Of the viscosity and density, only the viscosity of the ink may be detected, or only the density of the ink may be detected, and both the viscosity and density of the ink are detected. It may be like this.

Next, the resonance frequency and resonance time of the thin portion 812 of the sensor 8 when the remaining amount of ink in the storage unit 71 is zero, when the ink concentration is low, and when the ink concentration is high. A specific example of the insertion loss will be described.
FIGS. 10A and 10B show the sensor when the remaining amount of ink in the liquid detection device provided in the printing apparatus shown in FIG. 1 is zero, when the ink density is low, and when the ink density is high. It is a graph which shows the relationship between the frequency of vibration of a thin part, and insertion loss. The vibration mode is a thickness sliding mode.

In the specific example shown in FIG. 10, the resonance frequency f ₁ when the remaining amount of ink is zero is 70 MHz, and the resonance frequency f ₂ when the ink concentration is low is −400 ppm with respect to f ₁ . The resonance frequency f ₃ when the ink density is high is −600 ppm with respect to f ₁ . Thus, the resonance frequency is higher when the remaining amount of ink is zero than when it is not zero. The resonance frequency when the ink density is low is higher than the resonance frequency when the ink density is high.

  Further, the insertion loss at resonance when the remaining amount of ink is zero is 2 dB, the insertion loss at resonance when the ink density is low, and the resonance when the ink density is high. The insertion loss at that time is 10.5 dB. Thus, when the remaining amount of ink is zero, the insertion loss at resonance is smaller than when it is not zero. The insertion loss at resonance when the ink density is low is smaller than the insertion loss at resonance when the ink density is high.

  The oscillation circuit 111 of the liquid detection device is formed by electrically connecting the electrodes 82 and 83 of the sensor 8 to the main circuit 112 in the loaded state. The oscillation circuit 111 is not particularly limited as long as it can resonate the thin portion 812 of the sensor 8. For example, various oscillators such as a Colpitts oscillation circuit, a Hartley oscillation circuit, and a feedback oscillation circuit are available. Can be used.

  The storage unit 108 includes a storage medium (recording medium) that stores (records) calibration curves such as arithmetic expressions and tables, various information, data, programs, and the like. This storage medium includes, for example, RAM (Random Access Memory: including both volatile and nonvolatile), FD (Floppy Disk (“Floppy” is a registered trademark)), HD (Hard Disk), CD-ROM (Compact It is composed of a magnetic or optical recording medium such as a disc read-only memory or a semiconductor memory. Control such as writing (storage), rewriting, erasing, and reading in the storage unit 108 is performed by the control unit 105.

The control unit 105 has a function of controlling a printing operation, for example, a droplet discharge operation of the inkjet head 106. That is, the control unit 105 operates (drives) each unit of the printing apparatus 100, for example, the inkjet head 106, the display unit 107, the oscillation circuit 111 (main circuit 112), the first measurement circuit 113, and the second measurement circuit 114. Etc. are controlled respectively.
Further, the control unit 105 is inputted with measured values from the first measurement circuit 113 and the second measurement circuit 114 and signals from an operation unit (operation means) (not shown) as needed.

The control unit 105 includes, for example, a microcomputer or a CPU (Central Processing Unit) that includes a calculation unit, a memory, and the like.
It should be noted that the control unit 105 determines whether or not the remaining amount of ink (liquid remaining amount) in the storage unit 71 is almost zero, and the liquid for determining the viscosity and concentration of the ink (liquid) in the storage unit 71. The main function with the condition acquisition means is achieved (configured).

As the display unit 107, for example, a liquid crystal display device including a liquid crystal panel, an EL display device including an EL panel, a CRT, or the like, various displays that display an electronic image, or the like can be used.
The display unit 107 displays the presence / absence of ink in the storage unit 71 of the ink cartridge 1, the viscosity and concentration of the ink, information related thereto (for example, the fact that the ink cartridge 1 needs to be replaced), and the like.
Note that the notifying means is not limited to the display unit 107, and for example, a means for notifying by voice using a speaker may be used.

Next, the operation (operation) of the liquid detection device will be described.
Under the control of the control unit 105, first, the oscillation circuit 111 is operated. Thereby, the thin part 812 of the sensor 8 resonates (vibrates at the resonance frequency) in the thickness-slip mode.
In this case, the leakage of vibration from the thin part 812 is suppressed (or prevented) by the thick part 813 around it (peripheral part) and the thickness-slip mode is used as the vibration mode. Thus, the vibration of the thin portion 812 can be reliably confined in the recess 811 (only the thin portion 812 can be vibrated substantially), and vibration leakage can be prevented.

  Next, the second measurement circuit 114 is operated, and processing for obtaining the insertion loss at the time of resonance of the thin portion 812 is executed. That is, the signal (voltage) corresponding to the voltage between the electrode 82 and the electrode 84 of the sensor 8 and the signal (voltage) corresponding to the voltage between the electrode 83 and the electrode 84 are respectively the second measurement. The second measurement circuit 114 is input to the circuit 114, for example, by changing the gain of the amplifier or performing A / D conversion to obtain the voltage level of these signals, and at the time of resonance of the thin portion 812 The insertion loss is obtained and sent to the control unit 105.

The control unit 105 compares the detected insertion loss at the time of resonance of the thin portion 812 with a threshold value, and determines whether or not the remaining amount of ink in the storage unit 71 is zero.
As a result, when the remaining amount of ink is not zero, the first measurement circuit 113 is operated, and a process for obtaining the co-frequency of the thin portion 812 is executed. That is, a signal (voltage) corresponding to the voltage between the electrode 83 and the electrode 84 of the sensor 8 is input to the first measurement circuit 113, and the first measurement circuit 113 has a wave number within a predetermined time of the signal. (Number of pulses) is counted, and the resonance frequency of the thin portion 812 is obtained and sent to the control unit 105.
The control unit 105 obtains the ink concentration in the storage unit 71 based on the detected resonance frequency of the thin portion 812 using a calibration curve such as an arithmetic expression or a table.

On the other hand, when the ink remaining amount is zero, the process for obtaining the ink density is not executed.
The display unit 107 displays the presence / absence of ink in the storage unit 71, the ink concentration, and the like. In this case, the ink density may be displayed in stages, such as high density, normal density (standard density), and low density, or may be displayed continuously.

As a result, the user can accurately know that there is still ink in the ink cartridge 1, the density of the ink, and the ink in the ink cartridge 1 is almost completely exhausted (used up).
As described above, according to the liquid detection device of this embodiment, the vibration of the thin portion 812 of the sensor 8 can be reliably confined in the recess 811 (only the thin portion 812 can be vibrated substantially). Since the leakage of vibration can be prevented, the resonance frequency of the thin portion 812 and the insertion loss at the time of resonance can be detected with high accuracy, whereby the remaining amount of ink in the storage portion 71 becomes almost zero. And the viscosity and concentration of the ink can be accurately detected.

  Further, the ink is in contact with the thin portion 812 of the sensor 8 until the remaining amount of ink becomes almost zero, and when the remaining amount of ink becomes almost zero, the ink in contact with the thin portion 812 The sensor 8 (piezoelectric member 81) is provided so that the concave portion 811 side of the thin portion 812 faces downward and is exposed to the flow path 73, so that the remaining amount of ink is almost the same. When zero is reached, first, the ink level in the recess 811 is lowered, and the ink in contact with the thin portion 812 is reliably separated from the thin portion 812. When the ink is separated from the thin portion 812, the resonance frequency of the thin portion 812 and the insertion loss at the time of resonance change significantly, thereby accurately and reliably detecting that the remaining amount of ink is almost zero. can do.

  Furthermore, the flow path 73 disposed below the concave portion 811 of the sensor 8 is formed in a substantially U-shape, and the concave portion 811 of the piezoelectric body 81 is located in the folded portion 731, so that When the remaining amount of ink in the portion 71 becomes almost zero, it is possible to prevent ink from accumulating below the thin portion 812 and contact the ink with the thin portion 812. Thus, it can be detected more accurately and reliably that the remaining amount of ink is almost zero. Further, since the flow path 73 is formed in a substantially U shape, the ink flows smoothly.

In addition, a recess 811 is formed in the piezoelectric body 81, and the overall strength (rigidity) can be increased by the thick portion 813 while the thin portion 812 has a predetermined thickness.
In addition, the wiring to the sensor 8 is made only on the upper electrodes 82 and 83 of the piezoelectric body 81 and not on the lower electrode 84. Therefore, there is no need to route the wiring in the flow path 73, and mounting is easy. It can be carried out.

<Second Embodiment>
Next, a second embodiment of the present invention will be described. The description will focus on differences from the first embodiment described above, and description of similar matters will be omitted.
In the liquid detection device of the second embodiment, the electrode (common electrode) 84 is omitted, and the ink (liquid) has conductivity, except that it also serves as the common electrode. This is the same as the first embodiment described above.

In this embodiment, when the remaining amount of ink in the storage unit 71 is almost zero, it is equivalent to the case where there is no common electrode, and even if the oscillation circuit 111 is operated, the thin portion 812 of the sensor 8 vibrates ( Does not resonate. Therefore, the control unit 105 detects (detects) that the thin-walled portion 812 of the sensor 8 does not vibrate (resonate) when the oscillation circuit 111 is operated, thereby detecting the inside of the storage unit 71. It is determined that the remaining amount of ink is almost zero.
According to the second embodiment, the same effects as those of the first embodiment described above can be obtained.
The second embodiment can also be applied to a third embodiment described later.

<Third Embodiment>
Next, a third embodiment of the present invention will be described. The description will focus on differences from the first embodiment described above, and description of similar matters will be omitted.
FIG. 11 is a cross-sectional view (corresponding to FIG. 6) showing the main parts of the liquid detection device and the ink cartridge in the third embodiment. In the following description, in FIG. 11, the vertical direction is the vertical direction, and the horizontal direction is the horizontal direction.

As shown in FIG. 11, in the third embodiment, the flow path 73 is formed in the bottom 20 of the cartridge body 2 along a substantially vertical direction except for a part of the U-shaped portion.
The piezoelectric body 81 of the sensor 8 is located on the side of the flow path 73 (on the right side in FIG. 11), and the concave portion 811 side of the thin portion 812 is exposed to the flow path 73. That is, the concave portion 811 side of the thin portion 812 of the piezoelectric body 81 faces in a substantially horizontal direction (left side in FIG. 11), and the concave portion 811 constitutes a part of the flow path 73. The U-shaped portion of the flow path 73 is located on the left side of the piezoelectric body 81 in FIG.

According to the third embodiment, the same effects as those of the first embodiment described above can be obtained.
And in 3rd Embodiment, the discharge | emission property of the bubble from the flow path 73, especially the recessed part 811 can be improved.
As described above, the liquid detection device, the ink cartridge, and the printing device of the present invention have been described based on the illustrated embodiment. However, the present invention is not limited to this, and the configuration of each unit is an arbitrary function having the same function. It can be replaced with the configuration of In addition, any other component may be added to the present invention.

In the above-described embodiment, the ink cartridge is provided with one ink supply system including the reservoir, the discharge port, and the flow path. However, a plurality of ink supply systems are provided in the ink cartridge. It may be. For example, an ink cartridge provided with three ink supply systems for magenta, cyan and yellow, and an ink cartridge provided with four ink supply systems for magenta, cyan, yellow and black However, it goes without saying that the present invention can be applied.
In the above-described embodiments, the ink is described as an example of the liquid. However, in the present invention, the liquid is not limited to the ink.

1 is a perspective view showing a first embodiment of a printing apparatus including a liquid detection device of the present invention. FIG. 2 is a perspective view of a carriage provided in the printing apparatus shown in FIG. 1. FIG. 3 is a side view of the carriage shown in FIG. 2. FIG. 3 is a plan view of the carriage shown in FIG. 2. FIG. 2 is a perspective view showing an ink cartridge loaded in the printing apparatus (carriage) shown in FIG. 1. It is the sectional view on the AA line in FIG. FIG. 7 is a cross-sectional view (partially enlarged view of FIG. 6) showing a sensor of the liquid detection device provided in the printing apparatus shown in FIG. 1 and its peripheral part. It is a top view which shows the sensor of the liquid detection apparatus with which the printing apparatus shown in FIG. 1 was equipped. It is a block diagram which shows the main circuit part of the liquid detection apparatus with which the printing apparatus shown in FIG. 1 was equipped. 2 is a graph showing the relationship between the insertion loss and the frequency of vibration of the thin portion of the sensor in the liquid detection device provided in the printing apparatus shown in FIG. 1. FIG. 10 is a cross-sectional view (corresponding to FIG. 6) showing main parts of a liquid detection device and an ink cartridge in a third embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Ink cartridge 2 ... Cartridge main body 20 ... Bottom part 201 ... Convex part 21 ... Bottom surface 22 ... Convex part 221 ... Concave part 23 ... Valve mechanism 231 ... Valve body 232 ... Coil spring 233 ... Seal Member 24... Engagement piece 241... First convex portion 242... Second convex portion 25 and 26... Edge portion 27... Guide portion 28. 32 ... Grooves 33 and 34 ... Ribs 36 ... Hollow needle 361 ... Hole 37 ... Second recess 38 ... First recess 39 ... Third recess (guide groove) 40 ... Engagement Pin 41 ... Terminal 51 ... Sealing member 6 ... Circuit board 62 ... Terminal 71 ... Storage part 711 ... Bottom 712 ... Bottom wall 72 ... Discharge port 73 ... Flow path 731 ... Folded part 8 …… Sensor 81 …… Pressure Electrical body 811 ... Recessed part 812 ... Thin part 813 ... Thick part 82 to 84 ... Electrodes 821, 831 ... Terminal 100 ... Printing device 101 ... Carriage 102 ... Guide shaft 103 ... Belt 104 ... Carriage motor 105 ... Control unit 106 ... Inkjet head 107 ... Display unit 108 ... Storage unit 111 ... Oscillation circuit 112 ... Main circuit 113 ... First measurement circuit 114 ... Second measurement circuit P ... …recoding media

Claims (14)

Used in a liquid container comprising a storage part for storing liquid, a discharge port for discharging the liquid from the storage part, and a flow path for guiding the liquid from the storage part to the discharge port; A liquid detection device for detecting the presence or absence of liquid,
A recess is formed in the center, the center is a thin part that functions as a vibrator, and the piezoelectric body provided so that the recess side of the thin part is exposed to the flow path;
Resonating means for resonating the thin portion of the piezoelectric body;
Detecting means for detecting a resonance frequency and / or insertion loss at the time of resonance of the thin-walled portion of the piezoelectric body;
A discriminating means for discriminating whether or not the remaining amount of liquid in the reservoir is substantially zero based on the detection result of the detecting means;
Liquid condition acquisition means for determining the viscosity or concentration of the liquid in the reservoir based on the detection result of the detection means;
The vibration detection mode of the thin wall portion of the piezoelectric body is a thickness slip mode or a thickness mode.   The liquid detection device according to claim 1, wherein the concave portion side of the thin-walled portion of the piezoelectric body faces a lower side in the vertical direction, and a part of the flow path is configured by the concave portion.   The liquid detection device according to claim 1, wherein the concave portion side of the thin portion of the piezoelectric body faces a substantially horizontal direction, and a part of the flow path is configured by the concave portion.   The liquid detection device according to any one of claims 1 to 3, wherein the flow path is formed in a substantially U-shape, and the concave portion is located in a folded portion.   5. The resonance device according to claim 1, wherein the resonance means includes an oscillation circuit including a thin portion of the piezoelectric body, and the oscillation circuit is operated to resonate the thin portion of the piezoelectric body. The liquid detection device according to any one of the above.   The liquid detection device according to claim 1, wherein the piezoelectric body is made of quartz. An input electrode and an output electrode which are provided on a surface opposite to the concave portion of the thin portion of the piezoelectric body, and a common electrode which is provided on a surface of the thin portion of the piezoelectric body on the concave portion side. Have
By operating the resonance means and the detection means, the voltage between the output electrode and the common electrode is detected while applying a voltage between the input voltage and the common electrode, and based on the detection result. The liquid detection device according to claim 1, wherein a resonance frequency of the thin portion of the piezoelectric body is detected.   The liquid detection apparatus according to claim 7, wherein the liquid has conductivity and serves also as the common electrode.   The determination means determines whether or not the remaining amount of liquid in the reservoir is substantially zero.As a result, when it is determined that the remaining amount of liquid in the storage is not zero, the liquid condition acquisition means The liquid detection device according to claim 1, wherein the liquid detection device is configured to obtain a viscosity or concentration of the liquid in the storage unit.   The determination unit according to any one of claims 1 to 9, wherein the determination unit is configured to determine whether or not the remaining amount of liquid in the storage unit is substantially zero based on a detection result of the insertion loss by the detection unit. Liquid detection device.   11. The liquid detection according to claim 1, wherein the liquid condition acquisition unit is configured to obtain a viscosity or concentration of the liquid in the reservoir based on a detection result of the resonance frequency by the detection unit. apparatus.   The liquid detection device according to claim 1, wherein the liquid container is an ink cartridge in which ink is stored in the storage unit. An ink cartridge that is used in a state of being loaded in a printing apparatus that performs printing on a recording medium and is filled with ink,
A reservoir for storing ink as a liquid;
A discharge port for discharging ink from the reservoir;
A flow path for guiding the ink from the reservoir to the outlet;
A concave portion is formed in the central portion, the central portion is a thin portion that functions as a vibrator, and the piezoelectric portion is provided so that the concave portion side of the thin portion is exposed to the flow path,
The vibration mode of the thin portion of the piezoelectric body is a thickness sliding mode or a thickness mode,
In a state of being loaded in the printing apparatus, the thin portion of the piezoelectric body is resonated, and the resonance frequency and / or insertion loss at the time of resonance of the thin portion of the piezoelectric body is detected, and the storage is performed based on the detection result. An ink cartridge configured to determine whether or not the remaining amount of liquid in the unit is substantially zero and to determine the viscosity or concentration of the liquid in the storage unit. A printing apparatus that performs printing on a recording medium using an ink cartridge filled with ink, using the ink,
12. A printing apparatus comprising the liquid detection device according to claim 1, wherein the liquid container is an ink cartridge in which ink is stored in the storage unit.

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