JPH0781088A - Method and apparatus for driving ink jet head, and printer using the apparatus - Google Patents

Abstract

PURPOSE:To prevent the lowering of the relative displacement quantity of a vibration plate and an individual electrode by perfectly restoring the vibration plate by applying pulse voltage across the vibration plate and the individual electrode to allow residual charge to disappear. CONSTITUTION:A drive circuit 102a is constituted of transistors 106-109 and amplifiers 110-113. A nozzle restoring processing control signal, a printing control signal and a vibration plate restoring processing control signal are inputted to a control circuit and, on the basis of these signals, pulse voltages P1-P4 are appropriately outputted to the amplifiers 110-113. The transistors 106-109 are driven by the outputs of the amplifiers 110-113. As a result, the condenser 114 constituted of the vibration plate 5 and the individual electrode 21 is charged or discharged to emit an ink droplet 104 from a nozzle orifice 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of driving an ink jet head using static electricity as an actuator and a device therefor, and more particularly to eliminating the influence of residual charge remaining on a diaphragm constituting the actuator.

[0002]

2. Description of the Related Art Ink jet printers have many advantages such as extremely low noise during recording, high-speed printing capability, and the availability of inexpensive plain paper with a high degree of freedom in ink. Of these, the so-called ink-on-demand method, which ejects ink droplets only when recording is necessary, is currently mainstream because it does not require the collection of ink droplets unnecessary for recording.

As a conventional ink-on-demand driving method, for example, there is a driving method disclosed in Japanese Patent Publication No. 2-24218. In this driving method, a piezoelectric element that changes the volume of the pressure chamber that generates the ink ejection pressure is provided, and an electric pulse in the same direction as the polarization voltage of the piezoelectric element is applied to the piezoelectric element in a standby state, The volume of the pressure chamber is reduced by charging, the piezoelectric element is gradually discharged during ink ejection to increase the volume of the pressure chamber, and then an electrical pulse is applied to the piezoelectric element again to rapidly move the piezoelectric element. Ink is ejected from the nozzle by charging and reducing the volume of the pressure chamber. In this driving method, in order to eject the ink droplets most efficiently at a low voltage, the voltage is applied to the piezoelectric element again in the vicinity of the maximum value of the damping vibration of the ink system that occurs when the ink is sucked into the pressure chamber. Rapidly reducing the volume of the pressure chamber.

On the other hand, an ink jet head which uses an electrostatic force to drive an actuator has, for example, USP 4,5.
The structure disclosed in 20,375 is known.

US Pat. No. 4,520,375 is composed of a capacitor, which is composed mainly of two capacitor plates facing each other with a gap mainly by an insulating means, and a reservoir for containing ink, and one of the capacitor plates is, for example, one of them. By forming a thin diaphragm made of silicon semiconductor and applying a time-varying voltage to the capacitor, mechanical vibration is generated in the diaphragm, and in response to the movement of the diaphragm, for example, ink such as ink. A liquid ejecting apparatus that ejects liquid from a nozzle is disclosed.

[0006]

The above-mentioned conventional method for driving an ink jet head is one of the most suitable methods for the ink-on-demand system using a piezoelectric element as an actuator.

However, in the case of driving an ink jet head using electrostatic force for driving the actuator shown in USP 4,520,375 by the ink-on-demand method, the above-mentioned driving method using a piezoelectric element is simply applied. However, the following problems occur and it is difficult to put them into practical use.

An ink jet head using static electricity as an actuator is different from one using a piezoelectric element, and after a pulse voltage is applied between the diaphragm and individual electrodes, electric charges remain in the dielectric between the diaphragm and the electrodes, The electric field generated by this residual charge reduces the relative displacement between the diaphragm and the individual electrodes. This reduction in the relative displacement amount causes ejection failure such as the ejection amount of ink droplets and the ink speed, which leads to deterioration of print quality such as print density and pixel shift, and deterioration of reliability such as pixel omission. There was a problem.

Further, the residual charge is, as will be described later,
Since the magnitude of the applied voltage varies depending on the history of the applied voltage in the past, the relative displacement amount between the diaphragm and the individual electrode is not fixed uniquely and becomes unstable. The ejection speed and the like became unstable, and in any case, it became a factor of lowering the reliability such as defective print quality such as print density and pixel shift and pixel omission.

The present invention has been made to solve the above problems, and eliminates the adverse effect of the residual charge between the diaphragm and the electrode on the drive of the ink jet head.
Provided is a method for driving an inkjet head and a device for stabilizing the relative displacement between a diaphragm and individual electrodes.
It is an object of the present invention to provide a printing apparatus that can obtain good print quality.

[0011]

A method for driving an ink jet head according to the present invention comprises a nozzle, an ink flow path communicating with the nozzle, a vibration plate provided in a part of the flow path, and a vibration plate facing the vibration plate. With the electrode provided, deform the diaphragm,
In a method of driving an inkjet head that ejects ink droplets from a nozzle to perform recording, the diaphragm is deformed by electrostatic force and a first voltage used for normal recording and a second voltage different from the first voltage. And at a predetermined time, the second
The voltage is used to drive the diaphragm to stabilize the displacement of the diaphragm.

The second voltage different from the first voltage is a voltage having a polarity different from that of the first voltage, or a second voltage which gives a maximum voltage history to the dielectric between the diaphragm and the electrodes. The second voltage, which is higher than the first voltage and is different from the first voltage, is printed, for example, every time one dot or one line is printed, or at the time of initializing an apparatus equipped with an inkjet head, or nozzle recovery. It is applied when the operation is performed.

The ink jet head driving device of the present invention includes a nozzle, an ink flow path communicating with the nozzle, a vibration plate provided in a part of the flow path, and an electrode provided opposite to the vibration plate. In a drive device of an inkjet head that has, deforms, ejects ink droplets from a nozzle, and performs recording, the diaphragm is deformed by electrostatic force, and a first voltage used for normal recording is applied between the diaphragm and the electrode. It is characterized in that it has a driving means to be applied and a residual charge removing means of the diaphragm for applying a voltage having a polarity different from that of the first voltage between the diaphragm and the electrodes. The residual charge removing means applies an electric pulse having a voltage having a polarity different from that of the first voltage, for example, every time one dot or one line is printed, or when the nozzle recovery processing operation is performed.

In another aspect of the ink jet head driving device of the present invention, the nozzle, the ink flow path communicating with the nozzle, the vibration plate provided in a part of the flow path, and the vibration plate facing the vibration plate. In a driving device of an inkjet head that has an electrode provided and is deformed, ejects ink droplets from a nozzle, and performs recording, a diaphragm is deformed by electrostatic force and a first voltage used for normal recording is used. First applying a voltage history of maximum voltage to the dielectric between the diaphragm and the electrode,
And a second voltage higher than the voltage of 1) between the vibrating plate and the electrode. The power supply voltage adjusting means applies the second voltage, for example, at the time of initializing or nozzle recovery operation of the apparatus equipped with the inkjet head.

[0015]

In the present invention, by applying an electric pulse in the forward direction between the diaphragm of the ink jet head and the individual electrode, an attractive force due to electrostatic force is exerted between the diaphragm and the individual electrode facing the diaphragm. Works, and this electrostatic force deforms the diaphragm. Next, by releasing the electric pulse, ink droplets are ejected from the nozzle holes by the restoring force of the vibration plate. However, even if the electric pulse is released, the electric charge remains between the diaphragm and the individual electrode, and the electric field generated by the residual electric charge causes the diaphragm to bend without being completely restored. Then, as described above, the relative displacement amount between the vibration plate and the individual electrode is reduced, but in the present invention, a voltage having a polarity different from that of the driving voltage is applied before the driving voltage is applied, that is, ink is sucked. The residual charges are extinguished by applying before performing the operation.
Therefore, the diaphragm is not bent due to the residual charge, and the relative displacement amount between the diaphragm and the individual electrode does not decrease.

Further, the above-mentioned residual charge has a property that its magnitude varies depending on the voltage history, and its magnitude is particularly regulated by the maximum voltage applied. Therefore, in another aspect of the present invention, a maximum voltage larger than the driving voltage during printing is applied between the diaphragm and the electrode to maximize the residual charge, so that the driving voltage during printing is the maximum voltage. The amount of residual charge is kept constant even if it changes between the two. Therefore, the electric field due to the residual charges becomes constant, and the deflection of the diaphragm due to this becomes constant. Therefore, the relative displacement amount between the diaphragm and the electrode during printing is the difference between the deflection due to the drive voltage and the deflection (constant) due to the maximum voltage regardless of the voltage history, and is uniquely determined. , Will be stable.

[0017]

FIG. 2 is an exploded perspective view of an ink jet head in one embodiment of the present invention. The present embodiment shows an example of an edge eject type in which ink droplets are ejected from nozzle holes provided at the end of the substrate, but a face image ejecting ink droplets from nozzle holes provided at the upper surface of the substrate is used. It may be a cut type. 3 is a cross-sectional side view of the entire assembled inkjet head, and FIG. 4 is A- of FIG.
It is a line A arrow line view. Inkjet head 1 of this embodiment
Reference numeral 0 has a laminated structure in which three substrates 1, 2 and 3 having the structure described in detail below are stacked and joined.

The intermediate first substrate 1 is a silicon substrate, and a plurality of nozzle grooves 1 are formed on the surface of the substrate 1 in parallel at equal intervals from one end so as to form a plurality of nozzle holes 4.
1 and a recess 12 communicating with each nozzle groove 11 and forming a discharge chamber 6 having a diaphragm 5 as a bottom wall;
2 is a narrow groove 13 for an ink inflow port, which will form an orifice 7 provided at the rear of the nozzle 2, and a recessed part, which will form a common ink cavity 8 for supplying ink to each ejection chamber 6. 14 and. Also, the diaphragm 5
A concave portion 15 which constitutes the vibration chamber 9 for mounting an electrode described later is provided in the lower part of the. In this embodiment, each of the orifices 7 has three parallel thin grooves 13 in order to mainly increase the flow path resistance and to maintain the normal operation of the inkjet head even if one of the narrow grooves is clogged. Is formed.

In this embodiment, the distance between the vibrating plate 5 and the electrodes arranged to face the vibrating plate 5, that is, the gap portion 1
A length G of 6 (see FIG. 3, hereinafter referred to as “gap length”).
So that there is a difference between the depth of the recess 15 and the thickness of the electrode,
The space holding means is composed of a vibration chamber recess 15 formed on the lower surface of the first substrate 1. As another example, the recess may be formed on the upper surface of the second substrate 2. Here, the depth of the recess 15 is set to 0.6 μm by etching. The pitch of the nozzle grooves 11 is 0.72 mm and the width thereof is 70 μm.

Regarding the provision of the common electrode 17 to the first substrate 1, it is important that the work function of the metal material of the semiconductor and the electrode is large or small. In this embodiment, titanium is used as the common electrode material. Although platinum is used as an attachment and gold is used as an underlay of chromium, the present invention is not limited to this embodiment, and another combination may be used depending on the characteristics of the semiconductor and the electrode material. The resistivity of the semiconductor material used in this example is 8 to 12 Ωcm.

Borosilicate glass is used for the lower second substrate 2 bonded to the lower surface of the first substrate 1, and the vibration chamber 9 is formed by bonding the second substrate 2 to each other. Gold is sputtered by 0.1 μm on each position corresponding to the vibration plate 5 on the substrate 2 to form a gold pattern in substantially the same shape as the vibration plate 5 to form the individual electrodes 21. Individual electrode 2
1 has a lead portion 22 and a terminal portion 23. Furthermore, except for the electrode terminal portion 23, a Pyrex sputtered film is formed on the entire surface by 0.2
An insulating layer 24 is formed by coating with a thickness of μm to form a film for preventing dielectric breakdown and short circuit when the inkjet head is driven.

The upper third substrate 3 bonded to the upper surface of the first substrate 1 is made of borosilicate glass as with the second substrate 2. By joining the third substrate 3, the nozzle hole 4, the ejection chamber 6, the orifice 7, and the ink cavity 8 are formed. Further, the third substrate 3 is provided with an ink supply port 31 communicating with the ink cavity 8. The ink supply port 31 is connected to an ink tank (not shown) via a connection pipe 32 and a tube 33.

Next, the first substrate 1 and the second substrate 2 are anodically bonded at a temperature of 300 to 500 ° C. and a voltage of 500 to 800 V, and under the same conditions, the first substrate 1 and the third substrate 3 are joined together. And the ink jet head is assembled as shown in FIG. After joining the anode, the gap length G formed between the diaphragm 5 and the individual electrode 21 on the second substrate 2 is equal to the recess 1
5 and the thickness of the individual electrode 21, which is 0.5 μm in this embodiment. The gap G1 between the diaphragm 5 and the insulating layer 24 on the individual electrode 21 is 0.3 μm.

After the ink jet head is assembled as described above, the common electrode 17 and the terminal portion 23 of the individual electrode 21 are formed.
A drive circuit 102 is connected between the wirings 101 to form an inkjet printer. Ink 103
Is supplied to the inside of the first substrate 1 from an ink tank (not shown) through the ink supply port 31, and fills the ink cavity 8, the ejection chamber 6, and the like. Then, as shown in FIG. 3, the ink in the ejection chamber 6 is ejected as ink droplets 104 from the nozzle holes 4 when the inkjet head 10 is driven, and is printed on the recording paper 105.

Next, the electrical connection of this embodiment constructed as described above will be explained. In a structure including a metal-insulating layer-semiconductor layer, a so-called MIS structure, a space charge layer (also called a depletion layer) may or may not have a large difference in current value depending on the polarity of an applied voltage. It is known as a phenomenon due to the influence of. When the semiconductor material of the substrate is P-type silicon, it can be regarded as a conductor when a positive voltage is applied to the substrate electrode side, but when a negative voltage is applied, it is not regarded as a conductor due to the existence of the space charge layer and the capacitance is I know I have it.

FIG. 5 is a partially enlarged detailed view of the vibrating plate and the individual electrodes in this embodiment, and schematically shows the state of electric charges. P-type silicon is used for the first substrate 1, the first substrate 1 (vibration plate 5) side, that is, the common electrode 17 is connected to the drive circuit 102 so that the positive polarity and the individual electrode 21 side have the negative polarity, Common electrode 17 and individual electrode 21
This is the case where a pulse voltage is applied by the drive circuit 102 to.

The P-type silicon is doped with boron,
It is known that the electrons have the same number of holes as the number of doped boron because the number of electrons is insufficient. P
The holes 19 in the shaped silicon are repelled toward the insulating layer 26 side by the positive charge of the common electrode 17. Due to the movement of the holes 19, the acceptor (ionized boron) becomes
Since charges are supplied from the substrate electrode 17, holes flow in the first substrate 1 and a space charge layer is not generated, which can be regarded as a conductor. Further, the individual electrode 21 side is charged with a negative electric charge, and as a result, the applied pulse voltage generates an attractive force due to static electricity sufficient to bend the diaphragm 5. Therefore, the diaphragm 5 is bent toward the individual electrode 21 side.

FIGS. 6 and 7 are schematic diagrams focusing on the residual charge of the dielectric between the diaphragm and the individual electrodes of FIG.
Similar to FIG. 5, FIG. 6 shows a state when a voltage is applied, and FIG. 7 shows a state when the electric field is removed. Next, generation of residual charges will be described with reference to FIGS. 6 and 7. 6 and 7, as described above, the diaphragm 5 is a semiconductor, the common electrode 17 is made of metal, and they are ohmic-connected.

The diaphragm 5 is covered with an insulating layer 26. The insulating layer 24 formed on the individual electrode 21 faces the insulating layer 26 via the gap 16, and the insulating layer 26, the gap 16 and the insulating layer 24 form the insulating layer 27 as a whole. . Therefore, here, it can be regarded as a model in which the dielectric is interposed in the parallel plate capacitor constituted by the diaphragm 5 and the individual electrode 21. The dielectric corresponds to the protective film insulating layers 24 and 26.
When a voltage is applied to the parallel plates, the dielectric material cancels the applied electric field as shown in FIG. 6 (in the direction opposite to the electric field).
Polarization 28 is generated. Most of the polarized light 28 disappears in a short time when the applied voltage is cut off and the electric charge stored in the capacitor is discharged through the resistor 46. The delay time from the discharge to the disappearance of the polarization is called the relaxation time, which greatly differs depending on the type of polarization.

In the case of the polarization of the dielectric (insulating layer) inside the vibrating plate 5 and the individual electrode 21 of this embodiment, a comparison called ionic polarization or interface polarization other than atomic polarization or electronic polarization with a short relaxation time is made. It contains a polarization component with a long dynamic relaxation time. Ion polarization is generated by the movement of Na +, K +, B +, etc. inside the insulating layer along the applied electric field, and interface polarization causes contact between media having different dielectric constants when the dielectric has a heterogeneous structure. The polarization that occurs at the interface between the silicon oxide and the pure silicon. Therefore, in the dielectric 5 (24, 26) inside the vibrating plate 5 and the individual electrodes 21 of this embodiment, as shown in FIG. 7, a part of the polarization is completely generated by repeated application of an electric field or continuous application for a long time. The polarization remains for a long time without disappearing. As a result, the dielectric material has a residual polarization 29, and the residual electric field P created by the residual polarization between the diaphragm 5 and the electrode 21 causes a decrease in the relative displacement amount between the diaphragm 5 and the individual electrode 21.

FIG. 8 is a diagram showing the deflection of the diaphragm and the individual electrodes with time. FIG. 8A shows the diaphragm 5 and the individual electrode 21.
No voltage is applied between them, and the diaphragm 5 and the individual electrode 21 are parallel to each other as shown in the figure. Figure 8
(B) is a state when voltage is applied to the diaphragm 5 and the individual electrode 17, and the diaphragm 5 bends as shown in the figure. Here, the amount of the deflection is ΔV1. Next, FIG. 8C shows a state after the electric charge stored in the diaphragm 5 and the individual electrode 17 is discharged, and the diaphragm 5 is bent by the residual electric field generated by the residual charge even after the discharge, for example, The amount of deflection is ΔV2
And Therefore, it is understood that the relative displacement amount between the diaphragm 5 and the individual electrode 21 becomes ΔV1-ΔV2, and the relative displacement amount decreases.

The decrease in the relative displacement amount between the vibrating plate 5 and the individual electrode 21 causes the ejection failure such as the ejection amount of the ink droplets and the ink speed reduction as described above, and the reliability of the ink jet printer. And the print quality will be adversely affected. Therefore, in the present embodiment, as described later, the electric field in the direction opposite to that of FIG. 6 is applied between the diaphragm 5 and the individual electrode 21 to eliminate the above-mentioned residual charges.

FIG. 1 is a conceptual diagram of an ink jet printer according to an embodiment of the present invention. In the figure, 202 is a drive motor that moves the inkjet head or a print medium such as paper, and 203 is a printer that mainly includes the inkjet head 10 and the drive motor 202. The printer 203 prints characters and images by ejecting ink from the inkjet head 10 to reach the print medium while moving the inkjet head 10 and the print medium by the drive motor 202. Reference numeral 204 denotes a time measuring means, which measures time. 20
Reference numeral 6 denotes a nozzle clogging recovery processing means for controlling the nozzle clogging recovery processing. 207 is an input means,
Reference numeral 0 denotes a print calculation control unit 210 that performs print control and receives various input signals from the input unit 207 and performs various calculation controls. The print calculation control means 210 outputs an initialization signal for activating the clock means 204, a print control signal for controlling the printer 203, and performs various controls.
A storage unit 211 stores various data used in the arithmetic processing of the print arithmetic control unit 210. Two
Reference numeral 12 denotes a residual charge removing means for the diaphragm, which outputs a diaphragm recovery processing control signal in order to perform recovery processing for the residual charge on the diaphragm as described later.

Reference numeral 213 denotes a drive control circuit for the ink jet head 10, which has the circuit configuration shown in FIG. A nozzle recovery process control signal, a print control signal, and a diaphragm recovery process control signal are input to the drive control circuit 213, and the drive of the inkjet head 10 is controlled based on these control signals. Reference numeral 214 denotes a drive control circuit for the drive motor 202, which receives a nozzle recovery process control signal, a print control signal, and a diaphragm recovery process control signal, and controls the drive of the drive motor 202 based on these control signals.

FIG. 9 is a diagram showing the configuration of the drive control circuit of the ink jet head 10. This drive control circuit 21
3 is a control circuit 215 and a drive circuit 10 as shown.
2a. The drive circuit 102a includes transistors 106 to 109 and amplifiers 110 to 113. The control circuit 215 receives the nozzle recovery processing control signal, the print control signal, and the diaphragm recovery processing control signal, outputs pulse voltages P1 to P4 to the amplifiers 110 to 113 as appropriate based on those control signals, and the amplifiers 110 to 1
The transistors 106 to 109 are driven by the output of 13, and as a result, the capacitor 114 formed by the diaphragm 5 and the individual electrode 21 is charged or discharged, whereby the ink droplet 104 is ejected from the nozzle hole 4. Is ejected. Here, the resistor 115 is a resistor that determines the discharge rate, and the resistor 116 is a resistor that determines the charge rate. The time constant of charging and discharging is determined by each resistance value and the capacitance of the capacitor 114.

FIG. 10 shows the ink jet head 10 described above.
FIG. 2 is a schematic diagram of a printer equipped with the. 300 is recording paper 1
A platen 301 for transporting 05 is an ink tank for storing ink therein, and supplies ink to the inkjet head 10 via an ink supply tube 306.
Reference numeral 302 denotes a carriage, which is the inkjet head 10.
Is moved in a direction orthogonal to the conveyance direction of the recording paper 105. Reference numeral 303 denotes a pump, which is the inkjet head 10.
In the case of defective ink ejection, etc., it has a function of sucking the ink through the cap 304 and the waste ink collection tube 308 and collecting it in the waste ink reservoir 305.

FIG. 11 is a flow chart showing a control method of the ink jet printer of the embodiment of FIG.
2 is a flowchart showing the subroutine.
In FIG. 12, (a) shows the subroutine for the nozzle recovery operation, and (b) shows the subroutine for the printing operation. First, in step S0, the print calculation control means 21
Based on the instruction of 0, the initialization of the printer mechanism unit and the like is executed. At this time, the timing means 204 is reset at the same time and the timing starts. In the next step S1, the nozzle recovery operation is performed immediately after the power is turned on. This nozzle recovery operation is performed by a series of processes shown in steps SS1 to SS3 of the nozzle recovery operation subroutine of FIG.

First, the ink jet head 10 is driven by driving the drive motor 202 in step SS1.
Mount the carriage 302 with the cap from the standby position to the cap 3
Move to position 04. Next, in step SS2, a nozzle recovery operation, that is, a refresh operation is performed. The refreshing of the nozzles is performed by driving the vibrating plate 5 corresponding to all the nozzles in order to discharge defective ink that causes defective ink ejection such as thickened ink in the nozzle portion of the inkjet head 10. That is, the ink is ejected from the nozzle of a predetermined number of times. Normally, 10 to 200 ejections are performed for each nozzle, and the thickened defective ink is ejected outside the nozzle. The number of refresh discharges is determined in advance by the set time of the timer means 204.
After the refreshing of the nozzles is completed, the carriage 302 is returned to the standby position again in step SS3, and a series of refresh operations is completed. When power is turned on,
Generally, there is a high possibility that the head will not be used for a long time, so 160 to 200 ink ejections are executed.

After the completion of the nozzle refresh operation, the timer means 204 starts measuring a predetermined time. In step S2, the presence or absence of a timer-up signal is determined in order to determine whether or not the time counting means 204 has measured a predetermined time. Here, if the timer-up signal has been generated, the process proceeds to the nozzle recovery operation of step S8, and FIG.
The refresh operation shown in the nozzle recovery operation subroutine of (a) is performed, and the process proceeds to step S3. If the timer-up signal is not generated, the process directly proceeds to step S3. In step S3, it is determined whether to print. If printing is not performed, the process returns to step S2. In the case of printing, after resetting the clock means 204 in step S4, the printing operation is executed in step S5.

This printing operation is performed by a series of operations shown in steps SS10 to SS16 of the subroutine of the printing operation of FIG. The count value n is set to 1 in step SS10, and the carriage 302 is moved by one dot in step SS11. Then, in steps SS12 and SS13, the designated dot ink based on the print data is sucked and ejected. Then, in step SS14, refreshing (disappearance of residual charges) is performed only on the specific diaphragm 5 driven in steps SS12 and SS13. In the next step SS15, the count value n = n + 1 is incremented, and step SS
In 16, it is determined whether n is the final dot,
If it is not the final dot, the process returns to step SS11 and the above-described processing is repeated. If it is the final dot, the printing operation is ended, and in step S6, the carriage 3
02 is returned to the standby position again, and the paper is fed by a predetermined amount in step S7. Then, in step S9, it is determined whether or not the process is to be continued. If the process is to be continued, the process returns to step S2 to repeat the above process. When not continuing, all the processes are ended.

FIG. 13 is a timing chart showing the operation of the embodiment shown in FIGS. 1, 9 and 12. Here, in the standby state, since the capacitor 114 is held in the discharged state via the resistor R, the pulse voltage P4 is applied and the transistor 108 is turned on. First,
In the section a, the pulse voltages P1 and P4 are supplied, the transistors 108 and 107 are turned on, a positive voltage is applied to the diaphragm 5, and a negative voltage is applied to the electrode 21. As a result, the capacitor 114 is charged with the electric charge in the forward direction, the vibrating plate 5 is bent to the individual electrode 21 side by the attraction force by the static electricity, the pressure of the ejection chamber 6 is reduced, and the ink 103 is ejected from the ink cavity 8. It is replenished into the discharge chamber 6 through the orifice 7.

After that, when the hold section of b is passed,
In the section c, the pulse voltages P2 and P4 are supplied, the transistors 106 and 108 are turned on, and the charges accumulated in the capacitor 104 are rapidly discharged. As a result, the attraction force due to static electricity that acts between the diaphragm 5 and the individual electrode 21 disappears, and the diaphragm 5 is restored due to its own rigidity. By restoring the diaphragm 5,
The pressure in the ejection chamber 6 rapidly rises, and the ink droplets 104 are ejected from the nozzle holes 4 toward the recording paper 105. After that, as shown in the section of d, the diaphragm 5 is refreshed. Here, the pulse voltages P2 and P3 are supplied, the transistors 106 and 109 are turned on, and a negative voltage is applied to the diaphragm 5 and a positive voltage is applied to the individual electrode 21. An electric charge is charged in the capacitor 114 formed by the diaphragm 5 and the individual electrode 21. But,
This is the reverse voltage in the normal printing operation, and the charging direction is opposite. As a result, the residual charges in FIG. 7 disappear. After that, when the electric charge is discharged again in the section e, the residual electric charge disappears and is not left, so that the diaphragm 5 is not bent as shown in FIG. 8C and is completely restored. Therefore, the ink ejection amount that is ejected again through the next sections a2, b2, and c2 substantially matches the ink ejection amount that was ejected last time. In the present embodiment, the ink droplets 104 are ejected while eliminating the residual charge generated between the vibrating plate 5 and the individual electrode 21 for each dot as described above.

In this embodiment, the reverse voltage is applied in order to extinguish the residual charge, but the diaphragm 5 is also bent by the reverse voltage, so it is necessary to prevent ink droplets from being ejected. When a semiconductor is used for the vibrating plate 5, even if the magnitude of the reverse voltage is the same as the forward voltage, the amount of bending is small, and there is no risk of ink droplet ejection. Therefore, the power source can be shared as in the present embodiment. On the other hand, when a conductor is used for the diaphragm 5, if the magnitude of the reverse voltage is set to be the same as the forward voltage, ink droplets may be ejected. Therefore, the magnitude of the reverse voltage is reduced. There is a need. Although the P-type semiconductor substrate is used as the substrate in this embodiment, when the N-type semiconductor substrate is used as the substrate, the connection wiring between the drive circuit 102a and the inkjet head 10 is different from the case of the P-type semiconductor. You need to do the opposite.

FIG. 14 is a flow chart showing another control method of the ink jet printer of the embodiment of FIG.
FIG. 15 is a flowchart showing the subroutine. In FIG. 15, (a) shows the subroutine for the nozzle recovery operation, and (b) shows the subroutine for the printing operation. In this embodiment, the vibrating plate recovery operation is performed row by row. Step S4 of FIG.
Step SS12 for refreshing the diaphragm is inserted between the step 5 and the step 5, and in this step, the diaphragm of the above-described embodiment is refreshed. Therefore, the print operation subroutine of FIG.
The second step SS12 is deleted, and the other processes are the same.

FIG. 16 is a timing chart showing the operation of the embodiment shown in FIGS. 14 and 15. In this embodiment, the pulse voltages P2 and P4 are supplied in the section a every time the carriage 302 returns, and the transistor 10 is supplied.
6, 109 are turned on, the diaphragm 5 and the individual electrode 2
A reverse voltage is applied to 1 to eliminate the above-mentioned residual charge.

FIG. 17 is a flow chart showing still another control method of the ink jet printer of the embodiment of FIG. 1, and FIG. 18 is a flow chart showing its subroutine. In FIG. 18, (a) shows a nozzle / vibration plate recovery operation subroutine, and (b) shows a printing operation subroutine. In this embodiment, when the head nozzle is recovered, the diaphragm is also recovered. Steps S1 and S8 of FIG. 11 correspond to steps S1a and S8a of FIG. 17, and in these steps S1a and S8a, not only the nozzle recovery operation but also the diaphragm recovery process is performed. Therefore, FIG.
In the nozzle / vibration plate recovery operation subroutine of (a),
After the carriage 302 is moved to the standby position in step SS1, the next step is step SS12.
At 5, the diaphragm 5 is refreshed. Therefore, step SS12 of FIG. 12 is deleted from the print operation subroutine of FIG. 18 (b).

According to the first embodiment described above, for example, every other dot or every time one line is printed,
Alternatively, by periodically removing the residual charge based on timekeeping, the adverse effect of the residual charge can be avoided. Each of these aspects of the present embodiment may be used in combination. By removing residual charge in this manner, it is desirable to completely eliminate residual deflection of the diaphragm, but resetting the electrostatic actuator to a defined state allows complete retention of the diaphragm. Even if the bending is not removed, the residual bending is at least constant, and the relative displacement amount of the diaphragm is also constant. If the residual flexure is constant, there is an effect that the ink ejection amount and the ink ejection speed can be easily corrected by increasing the drive voltage according to the residual flexure.

Next, another aspect of the method of driving the ink jet head of the present invention will be described.

In FIG. 7, when the diaphragm and the individual electrodes are charged for a sufficiently long time and residual polarization is accumulated, the residual electric field P is the residual polarization ratio χ, the maximum electric field Emax in the voltage application history, Assuming that the permittivity is ε in vacuum, it is represented by P = εχEmax. That is, the residual electric field P is determined by the maximum electric field in the history of applied voltage, and the electric charge due to the residual electric field and the initial amount of deflection of the diaphragm 5 are also determined by the maximum electric field (voltage) in the history.

FIG. 20 is a diagram showing the deflection of the diaphragm and the individual electrodes with time. FIG. 20A shows an initial state of the diaphragm 5 without a voltage history. As shown in the figure, the diaphragm 5 is not bent, and the diaphragm 5 and the individual electrode 21 are parallel to each other. . FIG. 20B shows a state in which a voltage (30 V) is applied between the diaphragm 5 and the individual electrode 21 after (a), and the diaphragm 5 bends (distortion amount ΔV1) as illustrated. .
Next, FIG.20 (c) has shown the state of the diaphragm 5 after discharge. As described above, since there is a voltage history of 30 V, the diaphragm 5 is slightly bent (distortion amount ΔV2) from the initial state of FIG. 20A due to the residual electric field created by the residual charges even after discharging. The difference between the deflection amount of the diaphragm 5 shown in FIG. 20 (b) and the deflection amount of the diaphragm 5 shown in FIG. 20 (c) causes the ink on the diaphragm 5 to be removed and the excluded volume of the ink to be determined. The ink removal volume contributes to the ejection of ink droplets,
The amount is ΔV3 = ΔV1−ΔV2 (see FIG. 20B), which is the difference (relative displacement amount) in the bending amount of the diaphragm 5 in each state.

20D shows a state in which the diaphragm 5 is bent by applying a higher voltage (40V) next to that of FIG. 20C, and FIG. The state of the vibrating plate 5 when the switch is switched next to (d) to discharge is shown. At this time, since there is a voltage history of 40 V, the residual electric field is larger than the residual electric field in FIG. 20C, and the flexure amount ΔV4 is also larger than the flexure amount ΔV2 in FIG. 20C.

20 (f) is shown in FIG. 20 (e) after FIG. 20 (e).
It shows a state in which the diaphragm 5 is bent by applying the same voltage (30 V) as in (b). The amount of bending of the diaphragm 5 at this time is the same as the amount of bending in FIG. 20B (ΔV1).
Since there is a voltage history of 40 V in the state of FIG.
The excluded volume of ink determined by the relative displacement amount is shown in FIG.
Shown by ΔV5 = ΔV1−ΔV4, which is determined by the difference between the amount of deflection in the state of (e) and the amount of deflection in the state of FIG. 20 (f), and ΔV3> ΔV5. Therefore, when the ink jet head is driven in the state of FIG. 20 (f) where the maximum history voltage is 40V, the ink droplet ejection amount is as shown in FIG. 20 (b) where the maximum history voltage is 30V. The amount is smaller than the ejection amount of ink droplets when the inkjet head is driven. Therefore, it can be seen that the ejection amount of the ink droplets changes depending on the level of the residual charge amount inside the head actuator composed of the vibration plate 5, the individual electrodes 21, and the like.

FIG. 21 is a characteristic diagram showing how the ink ejection speed by a constant voltage (38V) driving voltage changes depending on the previous driving voltage.

20 shows the ink discharge speed after the ink jet head in the state of FIG. 20 (a) was driven at 38V and 10 minutes had elapsed. ,, are 39V,
After driving at 40V and 41V for 10 minutes, drive voltage is 3
The result of measuring the ink discharge speed by switching to 8V is shown. Here, the driving frequency of the inkjet head is 3 kHz.
It was driven at z and a charging pulse width of 30 μsec. 38 before
If a voltage larger than V is not applied, the ink ejection speed is about 4 m / s and the driving voltage is 38 V after 39 V.
Then, the ink ejection speed is about 3.3 m / s and the driving voltage is 40
At 38 V after V, the ink ejection speed is about 2.8 m / s.
At 38 V after the drive voltage of 41 V, the ink ejection speed is about 1 m / s. Thus, it can be seen that even if a constant drive voltage is applied, the ink ejection speed varies depending on the magnitude of the drive voltage applied before that. This is due to the above-mentioned residual charge.

The change in the relative displacement amount between the vibrating plate 5 and the individual electrode 21 as described above causes a change in the ink ejection speed, the ink droplet ejection amount, and the like, and as described above, the reliability of the ink jet printer and the printing. It adversely affects the quality. Therefore, in this embodiment, as will be described later, a maximum voltage is applied between the diaphragm 5 and the individual electrode 21 so that the residual charge amount becomes constant at the maximum value.
In the example of FIG. 21, the maximum voltage 4 is first set as the drive voltage.
When 1V is applied, even if a driving voltage of 39V or 40V is applied thereafter, the ink ejection speed of the driving voltage 38V is the same as the bending amount of the diaphragm 5 when the driving voltage 38V is applied and the driving voltage 41V. It is determined by the difference from the amount of bending due to the residual charge, and has a unique value and is stable.

FIG. 19 is a conceptual diagram of an ink jet printer according to another embodiment of the present invention. In the figure, reference numeral 412 is a power supply voltage adjusting means, and as will be described later, in order to avoid the influence of the remanent polarization of the dielectric between the diaphragm 5 and the individual electrode 21, the drive voltage Vn at the time of normal printing and the maximum The maximum voltage Vm (Vm> Vn) for giving the voltage history of the voltage is appropriately switched and output. The maximum voltage Vm should be determined in consideration of the tolerance of the power supply voltage. For example, if the drive voltage Vn during normal printing is 30V ± 10%, the maximum voltage Vm is set to at least 33V or more. Good. 41
3 is a drive control circuit of the inkjet head 10,
It has the circuit configuration shown in FIG. This drive control circuit 4
A nozzle recovery process control signal, a print control signal, and a drive voltage Vn or Vm are input to 13, and the drive of the inkjet head 10 is controlled based on these control signals.

Note that, in FIG. 19, other configurations and functions of the components are the same as those of the ink jet printer of FIG. 1, and therefore description thereof will be omitted.

FIG. 22 is a diagram showing the configuration of the drive control circuit of the ink jet head 10. This drive control circuit 4
Reference numeral 13 denotes a control circuit 415 and a drive circuit 1 as shown.
It is composed of 02b. The control circuit 415 receives the print control signal and the nozzle recovery processing control signal, and outputs the charge signal 51 and the discharge signal 52 based on these control signals. The drive circuit 102b includes transistors 41, 42, 4
It is composed of 4, 45 and the like.

In the drive control circuit 413, in the standby state, both the transistors 42 and 45 are turned off, and the drive voltage is not applied to the diaphragm 5-individual electrode 21. Therefore, the diaphragm 5 is displaced. Therefore, no pressure is applied to the ink in the ejection chamber 6. Next, the charging signal 51
Is turned on, the transistor 41 is turned on by the rising of the signal, and the transistor 42 is also turned on. Therefore, the drive voltage Vn (or Vm) is applied between the diaphragm 5 and the individual electrode 21, and a current flows in the direction of arrow A. As described above, the electric charge charged between the diaphragm 5 and the individual electrode 21 causes the diaphragm 5 to be attracted to the individual electrode 21 side by the electrostatic force acting between the both, and the diaphragm 5 is bent. As a result, the volume of the ejection chamber 6 increases and ink is sucked.

Next, when the charge signal 51 is turned off and the discharge signal 52 is turned on, the transistors 41 and 42 are turned off, so that the charging between the diaphragm 5 and the individual electrode 21 is stopped.
On the other hand, the transistor 44 is turned off, which turns on the transistor 45. When the transistor 45 is turned on, the charge accumulated between the diaphragm 5 and the individual electrode 21 is discharged in the arrow B direction through the resistor 46. In the figure, the resistor 46 is set to be considerably smaller than the resistor 43 and has a small time constant at the time of discharging, so that the resistor 46 is discharged in a time sufficiently shorter than the charging time. At this time, the vibrating plate 5 is released from the electrostatic force all at once, and returns to the standby position due to the rigidity of the vibrating plate 5 itself, suddenly presses the ejection chamber 6, and the pressure generated in the ejection chamber 6 causes the ink droplet 104 to be ejected into the nozzle hole. Discharge from 4. Although the P-type semiconductor substrate is used as the substrate in this embodiment, when the N-type semiconductor substrate is used as the substrate,
The connection wiring between the drive circuit 102b and the inkjet head 10 needs to be the reverse of that for the P-type semiconductor.

FIG. 23 is a flow chart showing the control method of the ink jet printer of the embodiment of FIG. In this embodiment, the high voltage is applied after the initialization. In step S0, initialization of the printer mechanism unit and the like is executed based on an instruction from the print calculation control unit 210. At this time, the clocking means 204 is reset at the same time to start clocking, and the drive motor 202 is driven to move the carriage 302 having the inkjet head 10 from the standby position to the position of the cap 304. In the next step S10, the power supply voltage adjusting means 412 selects the maximum voltage Vm and sets it to the drive control circuit 4 of the inkjet head 10.
It outputs to 13. The control circuit 415 is the print calculation control unit 2.
The print control signal from 10 is input, and the charge signal 51 and the discharge signal 52 are sequentially output to the drive circuit 102b.
The maximum voltage Vm is applied between the individual electrodes 21
While giving the voltage history of m to the dielectric between the diaphragm 5 and the individual electrode 21, the ejection operation for one shot is performed for all the noises. After that, the power supply voltage adjusting unit 412 returns the output voltage to the drive voltage Vn for normal printing. Then, in the next step S1, the nozzle recovery operation is performed immediately after the power is turned on. This nozzle recovery operation is shown in FIG.
Step SS of the nozzle recovery operation subroutine of (a)
The processing is performed by a series of processings 1 to SS3, but since these processings are as described above, detailed description will be omitted.

After the completion of the nozzle refreshing operation, the timer means 204 starts measuring a predetermined time. In step S2, the presence or absence of a timer-up signal is determined in order to determine whether or not the time counting means 204 has measured a predetermined time. Here, if the timer-up signal has been generated, the process proceeds to the nozzle recovery operation of step S8, and after the refresh operation shown in the above-described subroutine of the nozzle recovery operation of FIG. Proceed to.
If the timer-up signal is not generated, the process directly proceeds to step S3. In step S3, it is determined whether to print. If printing is not performed, the process returns to step S2. When printing, step S4
In step S5, the printing operation is executed after resetting the clock means 204.

This printing operation is performed by a series of operations shown in steps SS10 to SS16 of the printing operation subroutine of FIG. The count value n is set to 1 in step SS10, and the carriage 302 is moved by one dot in step SS11. Step SS1
In step 2 and step SS13, the designated dot ink is sucked and ejected. That is, the transistors 41 and 42 are turned on by the supply of the charging signal 51, and thereby the electric charge is charged between the diaphragm 5 and the individual electrode 21, and the diaphragm 5 is bent to the individual electrode 21 side by the attraction force by static electricity. Then, the pressure of the ejection chamber 6 is rapidly reduced, and the ink 103 is replenished from the ink cavity 8 into the ejection chamber 6 through the orifice 7. Next, the discharge signal 52 is supplied, the transistors 44 and 45 are turned on, and the diaphragm 5 and the individual electrode 21 are turned on.
The charge accumulated in the meantime is rapidly discharged. As a result, the attraction force due to static electricity that acts between the diaphragm 5 and the individual electrode 21 disappears, and the diaphragm 5 is restored due to its own rigidity. The remanent polarization at this time has a magnitude based on the voltage history of the maximum voltage Vm in the past, and the diaphragm 5
Remains slightly bent, the amount of the residual charge becomes constant regardless of the voltage history of the drive voltage even if the drive voltage changes up to the above-mentioned maximum voltage Vm.

Then, due to the restoration of the vibrating plate 5, the pressure in the ejection chamber 6 rapidly rises, and the ink droplets 104 are ejected from the nozzle holes 4 toward the recording paper 105. In the next step SS14, the count value is incremented as n = n + 1, and it is determined in step SS15 whether n is the final dot. If it is not the final dot, the process returns to step SS11 and the above-described processing is repeated. If it is the final dot, the printing operation is terminated, and step S6
In step S7, the carriage 302 is returned to the standby position again, and in step S7, the paper is fed by a predetermined amount. Then, in step S9, it is determined whether or not the process is to be continued. If the process is to be continued, the process returns to step S2 to repeat the above process. When not continuing, all the processes are ended.

FIG. 24 is a flow chart showing another control method of the ink jet printer of the embodiment of FIG. 19, and FIG. 25 is a flow chart showing its subroutine. In FIG. 25, (a) shows the subroutine for the nozzle recovery operation, and (b) shows the subroutine for the printing operation. In this embodiment, the high voltage is applied during the nozzle recovery operation, and the high voltage is applied when the nozzle is refreshed by the nozzle recovery operation in steps S1b and S8b of FIG. Figure 25
In step SS1 of (a), the drive motor 202 is driven to move the carriage 302 carrying the inkjet head 10 from the standby position to the position of the cap 304. Next, in step S10, the maximum voltage Vm is applied as the drive voltage in the same manner as in the above case, and the ink droplets 104 for one shot are ejected to all the nozzles. After that, the drive voltage Vn for normal printing is applied to refresh the nozzles in steps SS2 and SS3. In this embodiment, the maximum voltage Vm
However, the maximum voltage Vm may be applied when the nozzle is refreshed in step SS2 by omitting step S10 in FIG. 25A.

[0066]

As described above, according to the present invention, by applying a pulse voltage between the diaphragm and the individual electrode, electrostatic discharge is generated between the individual electrode and the diaphragm arranged opposite thereto. In the method of driving an inkjet head that ejects ink by exerting an attractive force, a pulse voltage in the opposite direction to the above pulse voltage is applied between the diaphragm and the individual electrodes to eliminate the residual charge. It is completely restored and the relative displacement between the diaphragm and the individual electrodes does not decrease.

According to another aspect of the present invention, by applying a drive voltage between the diaphragm and the individual electrode, an electrostatic attraction force is generated between the individual electrode and the diaphragm arranged so as to face the individual electrode. In the method of driving an ink jet head that discharges ink by operating, the maximum voltage that is larger than the driving voltage during normal printing is applied between the diaphragm and the individual electrodes to maximize the amount of residual charge and keep it constant. The relative displacement amount between the plate and the individual electrode is uniquely determined and stable regardless of the voltage history.

In this case, by setting the maximum voltage Vm to be 1.1 times or more that in normal printing, the above effect can be sufficiently obtained even when a power source having a normal output voltage tolerance is used. .

By applying the above-described driving method and driving device to a printing device, an inexpensive power supply device having normal characteristics can be used, and the influence of residual charges causing defective ejection of ink droplets can be achieved. Is eliminated, the ejection amount and ejection speed of the ink droplets are stable, and high print quality can be obtained. As a result, it has become possible to provide a practical printing apparatus to which the electrostatic actuator having the excellent characteristics of long life and low power consumption is applied.

[Brief description of drawings]

FIG. 1 is a conceptual diagram of an inkjet printer according to an embodiment of the present invention.

FIG. 2 is an exploded perspective view of the ink jet head of the embodiment.

FIG. 3 is a cross-sectional side view of the inkjet head of the embodiment.

FIG. 4 is a view taken along the line AA of FIG.

FIG. 5 is a partial detailed schematic diagram of a diaphragm and individual electrodes of the above-described embodiment.

6 is a schematic diagram focusing on polarization of the diaphragm and individual electrodes of FIG.

FIG. 7 is a schematic diagram focusing on the residual charges of the diaphragm and individual electrodes of FIG.

FIG. 8 is a schematic diagram showing the bending of the diaphragm in the above-described embodiment over time.

FIG. 9 is a diagram showing a configuration of a drive control circuit of the inkjet head of the embodiment.

FIG. 10 is a schematic diagram of a printer equipped with the jet head of the embodiment.

FIG. 11 is a flowchart showing a method of controlling the inkjet printer of the embodiment of FIG.

FIG. 12 is a flowchart showing a subroutine of FIG.

13 is a timing chart showing the operation of the embodiment of FIG.

14 is a flowchart showing another control method of the inkjet printer of the embodiment of FIG.

15 is a flowchart showing a subroutine of FIG.

16 is a timing chart showing the operation of the embodiment of FIG.

FIG. 17 is a flowchart showing another control method of the inkjet printer of the embodiment of FIG.

FIG. 18 is a flowchart showing the subroutine of FIG.

FIG. 19 is a conceptual diagram of an inkjet printer according to another embodiment of the present invention.

FIG. 20 is a schematic diagram showing the deflection of the diaphragm in the above-described embodiment over time.

FIG. 21 is a characteristic diagram showing how the ink ejection speed by a constant drive voltage (38V) changes depending on the previous drive voltage.

FIG. 22 is a diagram showing a configuration of a drive control circuit of the inkjet head of the embodiment.

23 is a flowchart showing a method of controlling the inkjet printer of the embodiment of FIG.

FIG. 24 is a flowchart showing another control method of the inkjet printer of the embodiment of FIG.

FIG. 25 is a flowchart showing a subroutine of FIG. 24.

Claims (13)

[Claims] 1. A vibrating plate having a nozzle, an ink flow path communicating with the nozzle, a vibrating plate provided in a part of the flow path, and an electrode provided so as to face the vibrating plate. In a method of driving an inkjet head that deforms a plate, ejects ink droplets from the nozzles, and performs recording, the vibrating plate is deformed by electrostatic force, and a first voltage used for normal recording and the first voltage are used. A method of driving an inkjet head, comprising a second voltage different from a voltage, and driving the diaphragm using the second voltage at a predetermined time to stabilize the displacement amount of the diaphragm. . 2. The method of driving an inkjet head according to claim 1, wherein the second voltage has a polarity different from that of the first voltage. 3. The second voltage is set to 1 dot or 1
3. The method for driving an inkjet head according to claim 2, wherein the voltage is applied each time line printing is performed or when the recovery processing operation of the nozzle is performed. 4. The second voltage is higher than the first voltage that gives a voltage history of a maximum voltage to a dielectric between the diaphragm and the electrode. A method for driving an inkjet head described. 5. The method for driving an inkjet head according to claim 4, wherein the second voltage is applied during an initialization or a nozzle recovery operation of an apparatus equipped with the inkjet head. 6. The method of driving an inkjet head according to claim 4, wherein the second voltage is at least 1.1 times or more the driving voltage. 7. A vibrating plate having a nozzle, an ink flow path communicating with the nozzle, a vibration plate provided in a part of the flow path, and an electrode provided so as to face the vibration plate. In a driving device of an ink jet head for deforming a plate, ejecting ink droplets from the nozzles, and performing recording, the vibrating plate is deformed by electrostatic force, and a first voltage used for normal recording is applied to the vibrating plate and the vibrating plate. An inkjet head comprising: a driving unit that applies between electrodes; and a residual charge removing unit that applies a voltage having a polarity different from that of the first voltage between the diaphragm and the electrodes. Drive. 8. The residual charge removing means of the vibration plate applies the second voltage every time one dot or one line is printed or when the recovery processing operation of the nozzle is performed. The drive device for an inkjet head according to claim 7. 9. A vibrating plate having a nozzle, an ink flow path communicating with the nozzle, a vibration plate provided in a part of the flow path, and an electrode provided so as to face the vibration plate. In a driving device for an inkjet head that deforms a plate, ejects ink droplets from the nozzles, and performs recording, the vibrating plate is deformed by electrostatic force, and a first voltage used for normal recording and the vibrating plate are used. A power supply voltage adjusting means for applying between the diaphragm and the electrode a second voltage higher than the first voltage, which gives a maximum voltage history to the dielectric between the electrode and the dielectric. Inkjet head drive device. 10. The inkjet head driving device according to claim 9, wherein the power supply voltage adjusting means applies the second voltage during an initialization or a nozzle recovery operation of an apparatus equipped with an inkjet head. 11. The second voltage is at least 1.1 times the driving voltage or more.
A driving device for the inkjet head described. 12. A vibrating plate having a nozzle, an ink flow path communicating with the nozzle, a vibration plate provided in a part of the flow path, and an electrode provided so as to face the vibration plate. A printing apparatus that uses an inkjet head driving method according to claim 1, wherein the printing apparatus uses an inkjet head that deforms a plate, ejects ink droplets from the nozzles, and performs recording. 13. A vibrating plate having a nozzle, an ink flow path communicating with the nozzle, a vibration plate provided in a part of the flow path, and an electrode provided so as to face the vibration plate. An inkjet head printing apparatus that deforms a plate, ejects ink droplets from the nozzles, and performs recording, comprising the inkjet head drive apparatus according to claim 7.