JPH11115201A - Ink jet recording device with ink end detector - Google Patents

Abstract

(57) Abstract: Provided is an ink jet recording apparatus provided with an ink end detector capable of detecting ink end accurately and using ink in a cartridge without waste. An ink jet head includes a plurality of nozzles, a discharge chamber communicating with each nozzle, and a reservoir communicating with the discharge chamber. By generating pressure in the ejection chamber 6, ink droplets are ejected from the nozzle 4. A part of the reservoir 8 is formed with a diaphragm 55 that can be deformed according to the pressure in the room. A change in the capacitance between the diaphragm 55 and the electrode 54 facing the diaphragm 55 is detected by the detection circuit 203, and when a change in the capacitance equal to or more than a predetermined value is detected, the ink end notification unit 204 notifies the user of the ink end. Inform.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet recording apparatus, and more particularly, to an ink end detector for detecting a remaining amount of ink supplied to an ink jet head.

[0002]

2. Description of the Related Art An apparatus and method for detecting the remaining amount of ink in an ink cartridge or an ink tank for supplying ink to a recording head with a pressure sensor is disclosed in, for example, Japanese Patent Application Laid-Open No.
No. 24954, JP-A-4-77264 and JP-A-4-20353.

In these methods, a pressure sensor is provided in the ink supply path in the ink reservoir from the recording head, and the amount of remaining ink is detected by detecting a decrease in pressure, whereby the ink shortage is directly detected. However, this also prevents the ink jetting from being stopped.

[0004]

FIG. 7 is a graph showing changes in the amount of ink consumed and the pressure applied to the recording head. In the graph, (a) shows an example in which ink is stored in an aluminum pack and pressure is actually measured in an ink jet printer of a type that supplies ink to a recording head.
(B) shows an example in which a foam (sponge) is used for the ink storage unit.

[0005] In order to prevent ink from dripping from the nozzles of the recording head, a constant negative pressure (negative pressure) is usually maintained in the recording head. As the consumption of ink progresses and the amount of ink in the pack decreases, the negative pressure sharply increases due to the restoring force of the aluminum pack and the increase in the osmotic pressure of the ink with respect to the foam. (Less than,
The force generated in the ink storage section and acting in the direction of returning the ink from the recording head is called back pressure. When ink droplets are ejected from the recording head, the insufficient ink is supplied to the recording head by the ejection. That is,
The ink flows into the recording head due to a decrease in the pressure inside the recording head due to the ejection of the ink droplet. If the back pressure generated on the ink storage unit side becomes larger than the negative pressure generated by the print head itself, it becomes impossible to supply ink to the print head. In other words, the ink remaining amount detecting devices described in the above publications detect the magnitude of the back pressure and notify that the ink has ended (ink end).

However, since the pressure sensor is provided in the ink supply path connecting the recording head and the ink reservoir, the back pressure generated on the ink reservoir side is larger than the negative pressure generated by the recording head itself. It has been difficult to accurately detect the point of time when it has become. For this reason, if the ink end is detected before the back pressure generated on the ink storage unit side becomes larger than the negative pressure generated by the recording head itself, the ink cartridge is replaced in a state where sufficient ink can be used. And wastes ink. Also,
When the ink end is detected after the back pressure generated on the ink storage unit side becomes larger than the negative pressure generated by the recording head itself, the printing operation is performed in a state where ink is not supplied to the recording head, that is, in a state where printing is not performed. After a while, the ink end is notified.

In addition, the ink supply path connecting the recording head and the ink reservoir is often formed of a rubber or resin tube, and mounting a pressure sensor in such a portion takes time and effort in the manufacturing process. In addition, there is a possibility that miniaturization of the device may be hindered.

An ink jet recording apparatus according to the present invention solves the above-mentioned problems, and provides an ink jet recording apparatus provided with an ink end detector capable of detecting the ink end accurately and using the ink in the cartridge without waste. Is what you do.

[0009]

An ink jet recording apparatus according to the present invention includes a plurality of nozzles, an independent ejection chamber communicating with each of the nozzles, and a common ink chamber communicating with the ejection chamber. In an ink jet recording apparatus that generates pressure in a chamber and discharges ink droplets from the nozzle, a diaphragm formed in a part of the common ink chamber and deformable according to the pressure in the chamber, and a diaphragm having a shape It has an ink end detecting means for detecting a change.

According to such a configuration, the ink end is detected by detecting the deformation of the shape of the diaphragm formed in the common ink chamber provided at the position closest to the ejection chamber (nozzle) in the ink supply path. It is possible to accurately detect the point in time when the back pressure generated on the storage unit side becomes larger than the negative pressure generated by the recording head itself.

As a pressure generating means for applying pressure to the discharge chamber for discharging the ink droplets, an electrode opposed to a diaphragm provided on a part of a wall surface of the discharge chamber with a predetermined gap is provided. A method of ejecting ink droplets by deforming the vibration plate by an electrostatic force obtained by applying a pulse voltage to the electrostatic actuator, and a vibration provided on a part of a wall surface of the ejection chamber. A method in which an electric pulse is applied to a plate and a piezoelectric element fixed to the vibration plate to deform the vibration plate to discharge ink droplets, and applies an electric pulse to a heating element provided inside a discharge chamber. This makes it possible to use a method of ejecting ink droplets from the nozzles by the vaporization pressure generated in the ejection chamber.

The means for detecting the deformation of the shape of the diaphragm is provided with, for example, an electrode facing the diaphragm with a gap, and a capacitance between the diaphragm and the electrode which changes according to a change in the interval between the diaphragm and the electrode. A method for detecting a change in

The method of detecting a change in the capacitance can be employed in the recording heads of the above-described respective ejection methods. From the viewpoint of facilitating the manufacturing process, it is desirable to use a sensor having the same structure and material as the actuator used for ejection as the sensor used for detecting the ink end. That is, the capacitance detection type ink end sensor is suitable for a recording head that ejects ink droplets using an electrostatic actuator.

As described above, when the capacitance detecting type is used as the means for detecting the deformation of the shape of the diaphragm, a reference voltage is applied between the diaphragm and the electrode, and the change in the voltage between the diaphragm and the electrode is detected. Alternatively, the ink end may be detected by using a unit that performs the operation. This method is a method suitable for always detecting the ink end during the printing process. Further, a reference resistor connected between the diaphragm and the electrode, a means for applying a reference pulse between the diaphragm and the electrode, and a rise time of the applied reference pulse may be detected to detect the ink end. This method is suitable for detecting the ink end before and after the printing process.

Regarding the material of the diaphragm, it is preferable to form a common ink chamber on a silicon substrate and to form a silicon diaphragm on the bottom surface since a uniform diaphragm can be formed by using anisotropic etching.

According to another aspect of the present invention, there is provided an ink jet recording apparatus having a plurality of nozzles for discharging ink droplets, comprising: an independent discharge chamber communicating with each of the plurality of nozzles; A diaphragm formed on the wall, a common ink chamber communicating with the ejection chamber,
A silicon substrate on which a diaphragm formed on the bottom wall of the common ink chamber is formed; and a first electrode which is a substrate bonded to the lower surface of the silicon substrate and faces each of the vibration plates at a predetermined interval. A lower substrate having a second electrode opposed to the diaphragm at a predetermined interval formed on an upper surface thereof, and charging and discharging between the vibration plate and the first electrode, whereby the electrostatic force generated there causes the electrostatic discharge. Driving means for deforming the diaphragm to eject ink droplets from the nozzles, detecting a change in capacitance between the diaphragm and the second electrode, and detecting an ink end when a predetermined amount of change has occurred. And ink end detecting means for recognizing. According to such a configuration, it is possible to obtain an electrostatic actuator for ejecting ink droplets and an ink end sensor of a capacitance detection type only by joining the two substrates, and to provide a highly accurate ink end sensor. The built-in recording head can be easily manufactured.

An ink jet control method according to the present invention relates to a control method for an ink jet recording apparatus as described above, in which a pressure is generated in a discharge chamber to discharge ink droplets from the nozzles, and a change in the shape of a diaphragm is detected. An ink end detection step, wherein the ink end processing is performed when a change in the shape of the diaphragm by a predetermined amount or more is detected in the ink end detection step.
The ink end detection may be performed before and after the printing process, or may be performed at any time during the printing process, for example, for each line and for each ejection.

In the above-described ink jet recording apparatus, the ink jet recording apparatus further includes a recovery processing means for sucking ink from the nozzles. In this case, it is desirable to perform an ink end detection step of detecting a change in the shape of the diaphragm before or after the recovery processing step. This is because the negative pressure in the recording head increases during the recovery process, so that the ink end cannot be detected accurately.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to an example in which a capacitance detection type ink end sensor is applied to a recording head which ejects ink droplets using an electrostatic actuator.

FIG. 1 is an exploded perspective view of the ink jet head of the present embodiment, which is partially shown in a sectional view. This embodiment shows an example of an edge eject type in which ink droplets are ejected from a nozzle hole provided at an end of a substrate, but a face eject method in which ink droplets are ejected from a nozzle hole provided in an upper surface portion of the substrate. It may be a type. FIG. 2 is a perspective view of the entire assembled ink jet head, and FIG.
FIG. 3 is a cross-sectional side view of an ink flow path of the inkjet head. An embodiment of the present invention will be described below with reference to the drawings.

The ink jet head 10 of this embodiment has a laminated structure in which three substrates 1, 2, and 3 having a structure described in detail below are overlapped and joined.

The intermediate first substrate 1 is a silicon substrate, and a plurality of nozzle grooves 1 formed at equal intervals in parallel from one end on the surface of the substrate 1 so as to form a plurality of nozzle holes 4.
1 and a recess 12 which communicates with each nozzle groove 11 to form a discharge chamber 6 which is a pressure generating section having a bottom wall as a vibration plate 5, and an orifice 7 provided at the rear of the recess 12. A narrow groove 13 for an ink inlet to be made;
A recess 14 that forms a reservoir (common ink chamber) 8 that is an ink supply unit for supplying ink to each ejection chamber 6, and a filter 5 provided at the rear of the recess 14
1 has a filter groove 52. On the bottom wall of the concave portion 14, a diaphragm 55 which is a part of the ink end detecting section is formed.

In the present embodiment, the length G (see FIG. 3, hereinafter referred to as “gap length”) of the opposing interval between the diaphragm 5 and the electrode 21 arranged opposite thereto is equal to that of the recess 15. The spacing means is constituted by the recess 15 for the vibration chamber formed in the second substrate 2 so as to have a difference between the depth and the thickness of the electrode. Further, as another example, the concave portion may be formed on the lower surface of the first substrate 1. The distance between the diaphragm 55 and the electrode 54 for the ink end sensor disposed opposite thereto is also approximately the length G.

In addition, when the common electrode 17 is applied to the first substrate 1, it is important that the work functions of the semiconductor and the metal material as the electrode are large and small. Although platinum or chromium is used as an underlayer and gold is used as an underlayer, the present invention is not limited to this embodiment. When the substrate 1 is a P-type semiconductor, the work function of the common electrode material is larger than that of the common electrode. Anything is fine,
In the case of an N-type semiconductor, any material may be used as long as the work function of the common electrode material is smaller.

The lower second substrate joined to the lower surface of the first substrate 1 is made of borosilicate glass,
The lower part of the vibrating plate 5 is provided with a concave portion 15 which constitutes the vibrating chamber 9 for mounting the electrode 21. Also,
A concave portion 16 for forming the electrode 54 is provided below the diaphragm 55 adjacent to the concave portion 15.

By joining the second substrate 2 to the first substrate 1, the vibration chamber 9 and the chamber 5 which becomes a part of the pressure sensor are formed.
3 is formed. At each position corresponding to the diaphragm 5 and the diaphragm 55 on the second substrate 2, an ITO conductive film is added to the.
The driving electrode 21 and the sensor electrode 54 are formed by sputtering 1 μm and forming an ITO pattern in substantially the same shape as the diaphragm 5 and the diaphragm 55. The drive electrode 21 is a lead 22
The sensor electrode 54 is connected to the terminal portion 23b by the lead portion 22b.

The upper third substrate 3 bonded to the upper surface of the first substrate 1 is made of borosilicate glass, like the second substrate 2. By joining the third substrate 3, the nozzle hole 4, the discharge chamber 6, the orifice 7, the reservoir 8, and the filter 51 are formed.

In the present embodiment, the filter 51 serves as an ink supply port at the same time, is connected to the connection pipe 32, and is connected to an ink tank (not shown) via the tube 33.

The first substrate 1 and the second substrate 2 have a temperature of 30
Anode bonding is performed by applying a voltage of 0 to 500 ° C. and a voltage of 500 to 1000 V. The first substrate 1 and the third substrate 3 are bonded under the same conditions, and an ink jet head is assembled as shown in FIG.

A silicon oxide film is formed on the surface of the substrate 1 by thermal oxidation so that the drive electrode 21 and the diaphragm 5 and the diaphragm 55 and the sensor electrode 54 are not short-circuited even if they come into contact with each other. If the thermal oxide film as the insulating film is too thick, it causes the electric field to weaken. On the other hand, if it is too thin, dielectric breakdown is apt to occur due to repeated electric field stress.
In this embodiment, the thickness of the thermal oxide film is 0.13 μm.

After assembling the ink jet head as shown in FIG. 2, the drive circuit and the detection circuit are connected by the FPC 101 between the common electrode 17 and the terminal 23a of the drive electrode 21, and to the terminal 23b of the sensor electrode 54. Then, an ink jet head unit is configured. Ink 103
Is a head folder 32 from an ink tank (not shown),
The ink is supplied to the inside of the inkjet head 10 through the filter 51 and fills the reservoir 8, the discharge chamber 6, and the like.

FIG. 3 is a schematic view showing an embodiment of the ink jet recording apparatus of the present invention equipped with the above-described ink jet head unit. Reference numeral 300 denotes a platen that conveys the recording paper 105, and 301 denotes an ink tank that stores ink therein, and supplies ink to the inkjet head 10 via an ink supply tube 306. Reference numeral 302 denotes a carriage, which controls the inkjet head 10 to record paper 1
05 in the direction perpendicular to the transport direction. By discharging the ink 104 from the inkjet head 10 by the drive circuit 40 at appropriate times while moving the carriage 302, it is possible to print any character or image on the recording paper 105.

Reference numeral 303 denotes a pump, which is a cap 30 for performing a recovery operation at the time of ink ejection failure of the ink jet head 10 or refilling ink.
4. A function of sucking ink through the waste ink collection tube 308 and collecting the ink in the waste ink reservoir 305.

In this embodiment, only the ink jet head 10 is provided on the carriage 302. However, the present invention is not limited to this, and the ink tank may be provided on the carriage. Alternatively, the present invention may be applied to a so-called disposable type in which the ink tank is integrally formed with the head (a type in which the ink jet head is replaced when the ink in the ink tank becomes empty).

FIG. 4 is a functional block diagram showing an embodiment of the present invention. Reference numeral 201 denotes a portion between the diaphragm 5 and the drive electrode 21.
A drive circuit for charging / discharging the nozzles and generating pressure in the discharge chamber 6 to discharge ink droplets from the nozzles 4;
3 is the capacitance between the diaphragm 55 and the sensor electrode 54,
Alternatively, it is a detection circuit for detecting a change in capacitance. Reference numeral 202 denotes an arithmetic circuit (CPU) for controlling the printer, and reference numeral 204 denotes an ink end notifying unit for warning a user when ink end is detected. The notification means 204 is, for example, an LED
Is turned on or a warning sound is issued to notify the user of the ink end.

Print data sent from a host (not shown),
The command is processed by the CPU 202 and the drive circuit 201 is controlled. As a result, charging and discharging are performed between the diaphragm 5 and the drive electrode 21, and an image is recorded on the recording paper. The detection circuit 203 appropriately detects a change in the pressure in the reservoir 8, and when a change in the pressure exceeding a predetermined value is detected by the detection circuit 203, the ink is sent to the user by the ink end notification unit 204 via the CPU 202. The end is announced.

As shown in FIG. 7, when the consumption of ink progresses and the amount of ink in the pack decreases, the negative force suddenly decreases due to the restoring force of the aluminum pack or the increase in the osmotic pressure of the ink with respect to the foam. The pressure (back pressure) increases.
Accordingly, the diaphragm 55 bends upward (in the direction of the arrow). Due to this bending, the diaphragm 55-the sensor electrode 5
The capacitance of the capacitor formed between the four decreases. This change in capacitance is detected by the detection circuit 203.

Hereinafter, a specific example of the detection circuit 203 and its operation will be described with reference to FIGS. FIG. 5 (a)
FIG. 4 is a circuit diagram showing a detection circuit 203a for applying a reference voltage between the diaphragm and the electrode and detecting a change in the voltage between the diaphragm and the sensor electrode. FIG. 5 (b)
Is the distance between the diaphragm 5 and the electrode 2 when the inkjet head is driven.
FIG. 3 is a waveform diagram showing a voltage waveform V1 between 1 and a voltage waveform V2 output from the detection circuit 203a.

The detection circuit 203a mainly includes resistors R1, R
2. It is composed of a diode D1 and an operational amplifier OP,
As shown, each element is connected so that a constant voltage is applied to a capacitor composed of the diaphragm 55 and the sensor electrode 54. The output terminal T is changed according to the change in the capacitance of the capacitor composed of the diaphragm 55 and the sensor electrode 54.
From 0, a voltage change between the diaphragm 55 and the sensor electrode 54 is output.

As shown in FIG. 5B, at times t0 to t0
Charging between the diaphragm 5 and the drive electrode 21 is performed until t1, and the diaphragm 5 bends toward the drive electrode 21. At this time, a negative pressure is generated in the vibration chamber 6, and the meniscus formed in the nozzle 4 retreats to the vibration chamber 6 side, and the ink in the reservoir 8 also flows into the vibration chamber 6, and also enters the reservoir 8. Negative pressure will be generated. Due to this negative pressure, the diaphragm 55 is deformed upward, and the output voltage V2 of the detection circuit 203a decreases as shown in the figure (w1 portion).

At time t1, charging between the diaphragm 5 and the drive electrode 21 is stopped. The diaphragm 5 is held while being attracted to the electrode 21. The negative pressure generated in the vibration chamber 6 gradually disappears as the ink flows from the reservoir 8. Then, the diaphragm 55 returns to the original state, and the output voltage V2 of the detection circuit 203a also returns to the voltage before the time t0 as illustrated (part w1).

From time t2 to time t3, discharge between the diaphragm 5 and the drive electrode 21 is performed, and the diaphragm 5 is bent in a direction of restoring the original shape by its elastic force. At this time, a positive pressure is generated in the vibration chamber 6, and ink droplets are ejected from the nozzle 4. The positive pressure generated here also propagates in the reservoir 8, the diaphragm 55 is deformed downward, the capacitance between the diaphragm 55 and the electrode 54 increases, and the output voltage V2 of the detection circuit 203a is shown in the drawing (w2 portion). Rise like.

When the ink droplets are ejected from the nozzles 4 and the vibration plate 5 is restored to the original shape, a negative pressure is generated in the ejection chamber 6 again. This negative pressure propagates into the reservoir 8, the diaphragm 55 is again deformed upward, and the output voltage V2 of the detection circuit 203a decreases as shown (w3 portion). When a negative pressure is generated in the reservoir 8 as described above, the diaphragm bends upward, the capacitance decreases, and the output voltage V2 decreases.
The larger the negative pressure generated, the more the diaphragm bends,
The output voltage V2 also drops significantly.

As described above, in addition to the negative pressure propagating from the discharge chamber 6, the back pressure generated on the ink storage side shown in FIG. As the back pressure increases, the amplitudes of the portions w1 and w3 of the voltage waveform V2 increase. (A portion indicated by a broken line in FIG. 5B.) By detecting the magnitude of the amplitude of the voltage waveform, the ink end can be accurately detected. For example, the detection circuit 20
3a is compared with the reference voltage Vref using a comparator (not shown), and the voltage V2 is set to the reference voltage Vref.
When detecting that it has fallen below ref, it notifies the user of the ink end and prompts the user to replace the cartridge. The magnitude of the reference voltage Vref is set in advance to a value corresponding to the amplitude of the voltage waveform V2 at the time when the back pressure generated on the ink storage unit side becomes larger than the negative pressure generated by the recording head itself.

As a result, it is possible to detect the moment when the back pressure rises sharply (part X in FIG. 7) and the ink cannot be supplied to the head, so that the ink cartridge can be replaced while the usable ink remains sufficiently. The ink end is not notified after the printing operation is continued for a while in a state where printing is not performed. The detection method described above is a method suitable for always detecting the ink end during the printing process.

FIG. 6A is a circuit diagram showing another embodiment of the detection circuit, and FIG. 6B is a waveform diagram showing input and output voltage waveforms of the detection circuit. Diaphragm 55
A reference resistor Rref is connected to the capacitor composed of the electrode 54 as shown in the figure. Reference pulse P on rectangle
When 0 is applied to the input terminal Vin of the detection circuit 203b,
A first-order slow system waveform is output to the output terminal Vout as shown. The rise time of this output waveform is determined by the time constant of the detection circuit (the resistance value of the reference resistor Rref × the capacitance C of the capacitor). Therefore, if the negative pressure (back pressure of the cartridge) in the reservoir 8 increases, the pressure changes depending on the time constant of the capacitor.
The capacitance between the four is reduced and the rise time is also reduced.
(In FIG. 6B, the waveform of the solid line shifts to the waveform of the dashed line.) By detecting the change in the rise time of the output waveform Vout, the ink end can be accurately detected. For example, the output voltage Vo of the detection circuit 203b
ut is converted to a reference voltage Vr using a comparator (not shown).
ef, time t2 and t3 from the time t0 when the output voltage Vout reaches the reference voltage Vref are measured, and when it is detected that the rise time is shorter than the reference time, the ink end is notified to the user and the cartridge is notified. Prompt for replacement. This reference time is the rise time when the capacitor composed of the diaphragm 55 and the electrode 55 indicates the capacitance at the time when the back pressure generated on the ink storage unit side becomes larger than the negative pressure generated by the recording head itself. It is set in advance to be substantially equal.

As a result, it is possible to detect the moment when the back pressure rises sharply (part X in FIG. 7) and the ink cannot be supplied to the head, so that the ink cartridge can be replaced while the usable ink remains sufficiently. The ink end is not notified after the printing operation is continued for a while in a state where printing is not performed.

The reference pulse P0 is applied between the diaphragm 55 and the electrode 54 before and after the printing process, for example, and the ink end is confirmed. In the case of a serial type printer, the reference pulse P0 may be applied every time one line is printed, and the ink end may be confirmed. The detection method described above is a method suitable for detecting the ink end before and after the printing process.

As shown in FIG. 3, when ink ejection is defective, the pump 303 is driven to perform a recovery process for discharging defective ink from the nozzles of the ink jet head 10 as needed. It is preferable to perform an ink end detection step of detecting a change in the shape of the diaphragm before or after the processing step. this is,
During the recovery process, the negative pressure in the print head increases,
This is because the ink end cannot be accurately detected.

In this embodiment, as a pressure generating means for applying pressure to the ejection chamber for ejecting ink droplets, the vibration plate in the ejection chamber is formed by an electrostatic force obtained by applying a pulse voltage to the electrostatic actuator. Although the method using the method of deforming and ejecting ink droplets has been described,
The present invention is not limited to this, and a method (piezo method) of deforming the vibration plate by applying an electric pulse to a piezoelectric element fixed to the vibration plate in the discharge chamber to discharge ink droplets, By applying an electric pulse to a heating element provided inside, a method of ejecting ink droplets from the nozzles by a vaporization pressure generated in the ejection chamber (thermal jet method) or the like can be used.

[0051]

As described above, according to the present invention, it is possible to provide an ink jet recording apparatus having an ink end detector capable of detecting the ink end accurately and using the ink in the cartridge without waste. Further, with this, there is no problem that the ink end is notified after the printing operation has been continued for a while without the ink cartridge being replaced in a state where the usable ink is sufficiently left and the printing is not performed. It works.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view of an inkjet head according to an embodiment of the present invention.

FIG. 2 is a perspective view of an inkjet head according to an embodiment of the present invention.

FIG. 3 is a perspective view of the inkjet printer according to the embodiment of the present invention.

FIG. 4 is a functional block diagram showing an embodiment of the ink jet printer of the present invention.

FIG. 5 is a circuit diagram and a waveform diagram showing an embodiment of an ink end detection circuit of the present invention.

FIG. 6 is a circuit diagram and a waveform diagram showing another embodiment of the ink end detection circuit of the present invention.

FIG. 7 is a graph showing a change in pressure applied to a recording head according to the amount of ink consumed in a cartridge.

[Explanation of symbols]

 Reference Signs List 4 Nozzle 5 Vibration plate 6 Discharge chamber 8 Reservoir 10 Inkjet head 21 Drive electrode 54 Sensor electrode 55 Diaphragm 201 Drive circuit 202 Operation circuit (CPU) 203 Capacitance detection circuit 204 Ink end notification means

Claims (14)

[Claims] A plurality of nozzles; an independent discharge chamber communicating with each of the nozzles; and a common ink chamber communicating with the discharge chambers. An ink jet recording apparatus that ejects droplets, comprising: a diaphragm formed in a part of the common ink chamber, the diaphragm being deformable according to the pressure in the chamber, and an ink end detecting unit for detecting a change in the shape of the diaphragm. Characteristic inkjet recording device. 2. An ink jet recording apparatus according to claim 1, further comprising an electrode facing said diaphragm with a gap, wherein said ink end detecting means changes the diaphragm in accordance with a change in a distance between said diaphragm and said electrode. An ink jet recording apparatus, which detects a change in capacitance between electrodes and recognizes an ink end when a predetermined amount of change has occurred. 3. The ink jet recording apparatus according to claim 2, wherein the ink end detecting means includes means for applying a reference voltage between the diaphragm and the electrode, and means for detecting a change in the voltage between the diaphragm and the electrode. An ink jet recording apparatus comprising: 4. An ink jet recording apparatus according to claim 2, wherein said ink end detecting means comprises: a reference resistor connected between said diaphragm and said electrode; a means for applying a reference pulse between said diaphragm and said electrode; An ink jet recording apparatus comprising means for detecting a rising time of a reference pulse. 5. The ink jet recording apparatus according to claim 1, wherein the ejection chamber and the common ink chamber are formed on a single silicon substrate, and the diaphragm is formed on a silicon substrate. An ink jet recording apparatus comprising: 6. An ink jet recording apparatus according to claim 1, wherein a pressure generating means for applying pressure to said discharge chamber is provided on a part of a wall surface of said discharge chamber; An electrostatic actuator having an electrode opposed to the diaphragm with a predetermined gap, wherein the diaphragm is deformed by an electrostatic force obtained by applying a pulse voltage to the electrostatic actuator, and ink is applied. An ink jet recording apparatus for discharging droplets. 7. An ink jet recording apparatus according to claim 1, wherein said pressure generating means for applying pressure to said discharge chamber includes: a diaphragm provided on a part of a wall surface of said discharge chamber; It consists of a piezoelectric element fixed to the diaphragm,
An ink jet recording apparatus characterized in that the vibration plate is deformed by applying an electric pulse to the piezoelectric element to eject ink droplets. 8. An ink jet recording apparatus according to claim 1, wherein said pressure generating means for applying pressure to said discharge chamber is a heating element provided inside said discharge chamber. An ink jet recording apparatus characterized in that an ink pulse is ejected from the nozzle by a vaporization pressure generated in the ejection chamber by applying an electric pulse to the nozzle. 9. An ink jet recording apparatus having a plurality of nozzles for discharging ink droplets, comprising: an independent discharge chamber communicating with each of the plurality of nozzles; and a diaphragm formed on a bottom wall of the discharge chamber. A silicon substrate having a common ink chamber communicating with the ejection chamber, a diaphragm formed on a bottom wall of the common ink chamber, and a substrate joined to a lower surface of the silicon substrate, A first electrode opposed to the first electrode at a predetermined interval;
A lower substrate having a second electrode formed on an upper surface thereof opposed to the diaphragm at a predetermined interval; and charging and discharging between the diaphragm and the first electrode, whereby the vibration is generated by an electrostatic force generated there. Driving means for deforming a plate to eject ink droplets from the nozzles; detecting a change in capacitance between the diaphragm and the second electrode; recognizing an ink end when a predetermined amount of change has occurred; An ink-jet recording apparatus comprising: 10. The control method for an ink jet recording apparatus according to claim 1, wherein: a printing step of generating pressure in the discharge chamber to discharge ink droplets from the nozzle; An ink end detecting step of detecting a change in shape, wherein the ink end detecting step performs an ink end process when a change in the shape of the diaphragm by a predetermined amount or more is detected. Control method. 11. The method of controlling an ink jet recording apparatus according to claim 1, wherein a pressure is generated in the discharge chamber to discharge ink droplets from the nozzle.
A method of controlling an ink jet recording apparatus, comprising: detecting a change in the shape of the diaphragm; and detecting a change in the shape of the diaphragm by a predetermined amount or more, and performing an ink end process. 12. The method for controlling an ink jet recording apparatus according to claim 11, wherein a change in the shape of the diaphragm is detected every one line printing. 13. The method according to claim 11, wherein a change in the shape of the diaphragm is detected every time an ink droplet is ejected. 14. A method for controlling an ink jet recording apparatus according to claim 1, further comprising a recovery processing means for sucking ink from said nozzle, wherein a pressure is generated in said discharge chamber and said ink is ejected from said nozzle. A printing step of discharging droplets, and a recovery processing step of discharging ink from a nozzle by the recovery processing means, and detecting a change in the shape of the diaphragm before or after the recovery processing step, and detecting a change in the shape by a predetermined amount or more. A control method for an ink jet recording apparatus, wherein an ink end process is performed when a change in the shape of a diaphragm is detected.