JPH08300652A - Ink jet head driving apparatus - Google Patents

Abstract

PURPOSE: To employ so-called 'pull-and-press' driving as a driving system of piezoelectric elements in constitution wherein respective piezoelectric elements are connected in a matrix form by wiring. CONSTITUTION: Respective segment transistors Q11-Q1k are successively turned OFF by the signal inputted from a timing control part 1 and respective data transistors Q21-Q2m are turned ON by the printing data outputted from a printing data output part 2. Therefore, the application of voltage to respective piezoelectric elements is stopped and the charge of the connected piezoelectric elements is discharged and the applied voltage to the piezoelectric elements is dropped. Subsequently, when the transistors Q11-Q1k are turned ON and the transistors Q21-Q2m are turned OFF, the applied voltage to the piezoelectric elements is rapidly boosted to the voltage V0 of a power supply 30. At the time of the rapid boosting of applied voltage, ink droplets are emitted from the nozzles of the piezoelectric elements by the 'pull and press' signal formed by the drop and rapid boosting of the applied voltage to the piezoelectric elements.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet head driving device for driving an ink jet head used in an ink jet recording device applied to a facsimile, a copying machine, a printer and the like.

[0002]

2. Description of the Related Art Conventionally, an ink jet recording apparatus in which ink droplets are ejected from a nozzle to a recording medium for printing has been widely used. In an inkjet head driving device used in such an inkjet recording device, a driving voltage is applied between electrodes of a piezoelectric element provided so as to form one side wall of a pressure chamber communicating with a nozzle to deform the piezoelectric element. Ink droplets are ejected from the nozzle by pressurizing the pressure chamber.

Since the piezoelectric element has a capacitive component, a pulsed current rushes in at the moment when the drive voltage is applied. Therefore, when a plurality of piezoelectric elements are driven at the same time, the inrush currents of the respective piezoelectric elements are superposed on each other and become excessive, causing fluctuations in the power supply. As a countermeasure against this, a power source with a large capacity must be adopted, which increases the space for parts and also increases the cost.

Therefore, in order to reduce this excessive current,
Generally, time-division driving is performed in which piezoelectric elements are arranged in a matrix having a plurality of rows and columns and the piezoelectric elements are driven for each column. For example, when the piezoelectric element is driven at a frequency of 5 kHz and the width of the driving voltage pulse is set to 50 μsec, 1 / (5 × 10 ³ ) × 1 / (50 × 10 ⁻⁶ )
The maximum number of divisions is 4.

Further, conventionally, a drive circuit has been proposed in which the number of drive elements is reduced with respect to the number of piezoelectric elements by performing time-division drive (Japanese Patent Laid-Open No. 4-77260). In this drive circuit, transistors as drive elements are arranged in a matrix on both sides of a piezoelectric element, k transistors are dynamically scanned, and m transistors are controlled by print data, so that a maximum of m × k transistors can be obtained. The nozzle is driven by k division in time division. For example, when 64 nozzles are driven by 8 × 8 matrix-structured transistors, the number of drive elements (transistors) is reduced to 8 + 8 = 16.

On the other hand, as a driving method of the piezoelectric element, push driving and pull driving are known. In the push-pull drive, voltage is not applied to the piezoelectric element in the steady state,
In this method, a voltage is applied during ink ejection to deform the piezoelectric element and pressurize the pressure chamber to eject ink. Also,
In the pulling drive, a voltage is applied to the piezoelectric element in a steady state to keep the pressurizing chamber in a pressurized state, the applied voltage is once reduced immediately before ejection to relax the pressurized state of the pressurizing chamber, and then the voltage is applied again. This is a method of applying pressure to pressurize the pressure chamber to eject ink.

As a driving method of the piezoelectric element in the ink jet head driving device, pulling driving is generally adopted. This is because compared to push-push drive, pull-push drive has an almost constant size of the first and second ink droplets, and the irregular vibration of the ink meniscus at the nozzle tip can improve the ink ejection frequency. This is because high ink ejection performance can be obtained.

[0008]

However, in the case of a long recording head having a large number of nozzles, the number of nozzles is large, and therefore an excessive current can be sufficiently reduced even when time-division driving is performed. Is difficult. For example, the number of nozzles is 2000
In the case of the four-division driving with a single nozzle, a maximum of 500 nozzles, that is, piezoelectric elements are simultaneously driven, so that the superimposed inrush current is still at a high level.

On the other hand, in the drive circuit disclosed in the above-mentioned Japanese Patent Laid-Open No. 4-77260, it is difficult to adopt the pulling drive as the drive system of the piezoelectric element. This is because each piezoelectric element is commonly grounded via the transistor on the dynamic scan side, and thus it is difficult to continue voltage application to the piezoelectric element in a steady state.

The piezoelectric element used in the recording head is generally manufactured by forming a piezoelectric material into a substrate by sintering or the like, and forming a pair of electrodes on both surfaces by screen printing or the like. By forming one electrode of this electrode pair in common and forming the other electrode individually at a position facing each pressurizing chamber, an individual piezoelectric element corresponding to each pressurizing chamber is formed. Therefore, if one of the electrodes is commonly grounded, the piezoelectric element can be easily manufactured.

However, in the case of a circuit in which the driving elements are arranged in a matrix on both sides of the piezoelectric element as in the above-mentioned conventional driving circuit, one electrode of each piezoelectric element is commonly grounded. Is difficult.

An object of the present invention is to solve the above problems and to provide an ink jet head driving device capable of sufficiently reducing the superposition of inrush current.

It is another object of the present invention to provide an ink jet head drive device having a structure in which each piezoelectric element is wired in a matrix, and pulling drive can be adopted as a driving method of the piezoelectric element.

Further, according to the present invention, each piezoelectric element is wired in a matrix, and one electrode of the piezoelectric element is commonly grounded. Ink jet driving can be adopted as a driving method of the piezoelectric element. An object is to provide a head drive device.

[0015]

In order to achieve the above object, the present invention provides an ink jet recording apparatus for ejecting ink onto a recording medium in accordance with print data from a plurality of nozzles arranged in a recording head. A piezoelectric element portion, which is provided so as to form one side wall of a pressure chamber that communicates with each nozzle and has a pair of electrodes, is wired in a matrix of m rows and k columns, and is time-divided k times. After each time, the voltage applied between the electrodes of the piezoelectric element is changed from the first level to the second level closer to the ground potential in order to temporarily relieve the pressure applied by the piezoelectric element in the pressure chamber, The piezoelectric element having the print data among the m pieces of the ejection signals for returning the applied voltage to the first level so as to pressurize the pressurizing chamber again to eject the ink from the nozzle. Is applied between the electrodes, the other (k in each row
-1) A time-division matrix drive circuit for applying a voltage signal such that ink is not ejected from the nozzles is provided between the electrodes of the one piezoelectric element (claim 1).

According to this structure, each piezoelectric element wired in a matrix of m rows and k columns is time-divided k times, and each time, each piezoelectric element communicates with a nozzle having print data in m rows. A striking signal is applied between the electrodes of the piezoelectric element forming the pressure chamber.

Further, one of the pair of electrodes of each piezoelectric element is grounded (claim 2).

According to this structure, one electrode of each piezoelectric element wired in a matrix of m rows and k columns is commonly grounded, so that the electrodes of the piezoelectric element can be easily formed. Become.

Further, the time division matrix drive circuit is
When the voltage applied between the electrodes of the piezoelectric element having the print data is changed from the first level to the second level and returned to the first level in each of m times in each column. , The voltage applied between the electrodes of the other (k−1) piezoelectric elements of the piezoelectric elements in each row is changed from the second level to the third level close to the first level to restore the first level. The third level is the pressure applied to the pressure chamber by the piezoelectric element when a signal for returning from the third level to the first level is applied between the electrodes of the piezoelectric element. It is set to a value such that ink is not ejected from the nozzle (claim 3).

According to this structure, in time-division driving,
At each time, the applied voltage between the electrodes of the other (k-1) piezoelectric elements in each row, that is, the piezoelectric elements that are not driven, is from the first level to the second level that is closer to the first level than the second level. It changes to the 3rd level and returns to the 1st level. At this time, the third level is set to a value at which ink is not ejected from the nozzle due to pressurization of the pressure chamber by the piezoelectric element when a signal for returning from the third level to the first level is applied between the electrodes of the piezoelectric element. Therefore, ink is not ejected from the nozzle by the application of this signal.

Further, the time division matrix drive circuit is
The first electrode is provided between the electrodes of the m piezoelectric elements in each row.
K charging parts for applying a level voltage, m discharging parts for changing the voltage applied between the electrodes of the k piezoelectric elements in each row to the second level by discharging, and the k charging parts. A timing control unit for sequentially turning off the voltage application by the charging unit for a predetermined time, and a print data output unit for performing the discharging operation by the m discharge units for the predetermined time when the print data exists. Every time the charging section is turned off, the voltage applied to the electrode of the piezoelectric element having the print data is changed from the first level to the first level among the m pieces in each column by the discharging operation of the discharging section for the predetermined time. The level is changed to two levels, and the applied voltage is returned to the first level by turning on the charging unit after the predetermined time, and the pullback signal is formed (claim 4).

According to this structure, the voltage application of the first level between the electrodes of the m piezoelectric elements in each column by the k charging sections is sequentially turned off for a predetermined time over k times. At this time, every m times, the voltage applied between the electrodes of the piezoelectric elements having print data is discharged for a predetermined time by the m discharge parts in synchronization with this OFF, and the second level Change. Then, at each time, the applied voltage returns to the first level by turning on the charging unit after a predetermined time, so that the pull-out signal is applied between the electrodes of the piezoelectric element having the print data.

In the charging section, the first-level voltage power source is connected to the other electrode of the piezoelectric element through a series circuit composed of a first switch element and a first resistor, respectively, and the discharging section is connected. Is configured such that the other electrode of the piezoelectric element is grounded via a series circuit including a second switch element and a second resistor, respectively, and the timing control unit controls ON / OFF of the first switch element. The print data output unit controls ON / OFF of the second switch element, and the ratio of the resistance value of the first resistor to the resistance value of the second resistor is the voltage of the first level to the first value. The voltage division level divided by 1 resistance and the 2nd resistance is the 3rd above.
It is set to reach the level (claim 5).

According to this structure, the first level voltage is applied from the first level voltage power supply to the other electrode of the piezoelectric element through the series circuit including the first switch element and the first resistor. Then, at each time, the voltage application to the m piezoelectric elements in each row is stopped for a predetermined time, and during this stop, the other electrode of the piezoelectric elements with print data among the m piezoelectric elements is the second switch element and the second switch element. The voltage applied between the electrodes of the piezoelectric element is discharged to the ground through a series circuit consisting of two resistors.
Change to the level. Then, after a predetermined time, the discharging is stopped and the applied voltage is returned to the first level by the charging unit.

Here, in a piezoelectric element wired in a matrix of m rows and k columns, each of the other m rows of (k) connected to the piezoelectric element changed to the second level by discharge at each time.
-1) The piezoelectric elements are charged by the charging section and simultaneously discharged by the discharging section. Therefore, the voltage applied between the electrodes of these piezoelectric elements changes to a voltage division level obtained by dividing the voltage of the first level by the first resistance and the second resistance. Then, after a predetermined time, the applied voltage changes from the divided voltage level to the first level due to the stop of the discharge and the voltage application, and the ink is ejected from the nozzle by the pressurization of the pressure chamber by the piezoelectric element when the signal is applied. Not discharged.

Further, the charging unit is configured such that the voltage power source of the first level is connected to the other electrode of the piezoelectric element via the first switch element and the current limiting resistor, respectively, and the discharging unit is The other electrode of the piezoelectric element is grounded via the current limiting resistor and the series circuit including the second switch element and the resistor, respectively, and the timing control unit controls ON / OFF of the first switch element. The print data output section controls ON / OFF of the second switch element, and the third level is equal to the first level (claim 6).

According to this structure, the first level voltage is applied from the first level voltage power supply to the other electrode of the piezoelectric element through the series circuit including the first switch element and the first resistor. Then, at each time, the voltage application to the m piezoelectric elements in each row is stopped for a predetermined time, and during this stop, the other electrode of the piezoelectric elements with print data among the m piezoelectric elements is the second switch element and the second switch element. The voltage applied between the electrodes of the piezoelectric element is discharged to the ground through a series circuit consisting of two resistors.
Change to the level. Then, after a lapse of a predetermined time, the discharge is stopped, the applied voltage is returned to the first level by the charging section, and the strike-off signal is applied between the electrodes of the piezoelectric element having the print data.

Here, in the piezoelectric element wired in a matrix of m rows and k columns, each of the other (k) rows of m rows connected to the piezoelectric element changed to the second level by discharge at each time.
-1) The one piezoelectric element is discharged through the current limiting resistor and the resistor by the discharging unit, but the voltage source of the first level is applied through the charging unit only through the current limiting resistor.
Therefore, since the voltage applied between the electrodes of these piezoelectric elements is maintained at the voltage of the first level, ink is not ejected from the nozzles communicating with the pressure chambers of these piezoelectric elements after a predetermined time.

Further, the time division matrix drive circuit is
The charging unit for applying the voltage of the first level between the electrodes of the piezoelectric element and the voltage applied between the electrodes of the m piezoelectric elements in each column are discharged to discharge the voltage from the first level close to the ground potential. 4 k levels of first discharge parts and m levels of voltage applied between the electrodes of each of the k piezoelectric elements in each row are changed from the 1st level to the 5th level close to the ground potential by discharging. Second discharging section, a first timing control section for turning on and off the charging section at a predetermined cycle, and a second timing for sequentially performing the discharging operation by the k first discharging sections for each off time of the charging section. The control unit and a print data output unit that causes the discharge operation by the m second discharge units to be performed for the off time of the charging unit when the print data is present, are provided for the first and second discharge units. Both are off times only When the electric operation is performed, the voltage applied to the electrodes of the piezoelectric element is set to change from the first level to the second level, the charging section is turned off, and the first discharging section is discharged. Each time the operation is performed, the voltage applied to the electrode of the piezoelectric element having the print data is changed from the first level to the second voltage among the m pieces in each column by the discharge operation of the second discharge section during the off time. When the charging unit is turned on after the off time, the applied voltage is returned to the first level to form the pull-back signal, and the fourth level is from the fourth level. The fifth level is set to a value such that ink is not ejected from the nozzle due to pressurization of the pressure chamber by the piezoelectric element when a signal returning to the first level is applied between the electrodes of the piezoelectric element. Is it the fifth level above? It is set to a value such that ink is not ejected from the nozzle due to pressurization of the pressurizing chamber by the piezoelectric element when the signal for returning to the first level is applied between the electrodes of the piezoelectric element (claim 7). ).

According to this structure, the voltage application of the first level between the electrodes of the piezoelectric element by the charging section is turned on in a predetermined cycle,
It is turned off, and in synchronization with this off, the voltage applied between the electrodes of the m piezoelectric elements in each column is sequentially k by the k first discharge parts.
The applied voltage is changed to the fourth level by discharging each off time of the charging unit over the times. At this time, each time, in synchronization with this OFF, the voltage applied between the electrodes of the piezoelectric elements having print data among the m number of the second discharge parts is discharged for the off time. The voltage applied between the electrodes of the piezoelectric element with print data changes to the second level by both of the first and second discharging units, and the applied voltage returns to the first level by the charging unit after the off time. As a result, a knock-out signal is applied between the electrodes of the piezoelectric element having print data.

On the other hand, the voltage applied between the electrodes of the piezoelectric elements without print data in each line is returned from the fourth level to the first level by the charging section after the off time. Further, in a piezoelectric element wired in a matrix of m rows and k columns, each of the other (k-m-row) connected to the piezoelectric element that is changed to the second level by the discharge of the first and second discharge parts each time. 1) The voltage applied between the electrodes of the one piezoelectric element is the
After the off time, the charging unit returns from the fifth level to the first level. Ink is not ejected from the nozzle due to the pressurization of the pressurizing chamber by the piezoelectric element when the signal for returning from the fourth and fifth levels to the first level is applied.

In the first discharge section, the other electrode of the piezoelectric element is grounded via a series circuit including a first switch element and a first resistor, and the applied voltage is discharged to the first electrode by grounding. The level is changed from 1 level to a level determined by the resistance value of the first resistor, and the second discharge portion is configured such that the other electrode of the piezoelectric element is connected via a series circuit including a second switch element and a second resistor. It is grounded and changes the applied voltage from the first level to a level determined by the resistance value of the second resistor by discharge. The second timing control section turns on and off the first switch element. The print data output section controls ON / OFF of the second switch element, and the resistance value of the first resistor is the OFF time of the first discharge section. The applied voltage is set to change from the first level to the fourth level by a discharge operation, and the resistance value of the second resistor is set to the applied voltage by the discharge operation of the second discharge unit during the off time. It is set so as to change from the first level to the fifth level (claim 8).

According to this structure, the voltage application of the first level between the electrodes of the piezoelectric element by the charging section is turned on in a predetermined cycle,
The piezoelectric element is turned off, and in synchronization with this off, the other electrode of the m piezoelectric elements in each column is discharged to the ground through a series circuit including the first switch element and the first resistor, and the electrodes between the electrodes of the piezoelectric element are discharged. The applied voltage changes to the fourth level determined by the resistance value of the first resistor. At this time, each time, in synchronization with this OFF, the other electrode of the piezoelectric element having print data among the m pieces in each column is connected for the OFF time through the series circuit including the second switch element and the second resistor. Discharged to earth. The voltage applied between the electrodes of the piezoelectric element with print data changes to the second level by both of the first and second discharging units, and the applied voltage returns to the first level by the charging unit after the off time. As a result, a knock-out signal is applied between the electrodes of the piezoelectric element having print data.

On the other hand, the voltage applied between the electrodes of the piezoelectric element without print data returns from the fourth level to the first level by the charging section after the off time. Further, in a piezoelectric element wired in a matrix of m rows and k columns, each of the other (k−m) rows of m rows connected to the piezoelectric element that has changed to the second level by the discharge of the first and second discharge portions each time. 1) The voltage applied between the electrodes of the piezoelectric elements changes to the fifth level determined by the resistance value of the second resistance by the second discharging unit, and returns from the fifth level to the first level by the charging unit after the off time. To do. Ink is not ejected from the nozzle due to the pressurization of the pressurizing chamber by the piezoelectric element when the signal for returning from the fourth and fifth levels to the first level is applied.

Further, the time division matrix drive circuit is
When the voltage applied between the electrodes of the piezoelectric element having the print data is changed from the first level to the second level and returned to the first level in each of m times in each column. , The voltage applied between the electrodes of the other (k-1) piezoelectric elements of each row of piezoelectric elements is changed to the second level, and then changed from the second level to the first level at a predetermined rate of change. The predetermined rate of change is the second
It is set to a value such that ink is not ejected from the nozzle due to pressurization of the pressure chamber by the piezoelectric element when a signal that changes from the level to the first level is applied between the electrodes of the piezoelectric element (claim) Item 9).

According to this structure, the piezoelectric elements are arranged in a matrix of m rows and k columns, each piezoelectric element is time-divided k times, and each time, the piezoelectric element has print data in m rows. A striking signal is applied between the electrodes. Here, in the piezoelectric element wired in a matrix of m rows and k columns, between the electrodes of the other (k-1) piezoelectric elements of m rows connected to the piezoelectric element that has changed to the second level each time. The voltage applied to the second level changes from the second level to the first level at a rate of change in which ink is not ejected from the nozzle due to the pressurization of the pressure chamber.

Further, the time division matrix drive circuit is
The first electrode is provided between the electrodes of the m piezoelectric elements in each row.
K first charging parts for applying a level voltage, and m discharging parts for changing the voltage applied between the electrodes of the k piezoelectric elements in each row to the second level by discharging.
A second charging unit that applies a voltage between the electrodes of each piezoelectric element at the predetermined change rate, and a voltage application by each of the first charging units is turned on and off in a predetermined cycle, and the k first first charging units are turned on and off.
A timing control unit that sequentially reduces the off time of the charging unit to the first off time, and a print data output unit that causes the discharge operation by the m discharge units to be performed for the first off time when the print data is present. And the first charging unit has the first
Every time it is turned off for the off time, the voltage applied between the electrodes of the piezoelectric elements having the print data among the m pieces in each column is changed from the first level by the discharge operation of the discharge part for the first off time. The applied voltage is changed to the first level by turning on the first charging unit after the first off time after changing to the second level.
The voltage is returned to the level to form the knock-out signal, and the voltage applied between the electrodes of the other (k-1) piezoelectric elements in each row is the second voltage when the discharge operation of the discharge unit is stopped. The second level is changed at the predetermined change rate by the voltage applied by the charging section (claim 10).

According to this structure, the voltage application of the first level between the electrodes of the piezoelectric element by the k first charging units is turned on and off in a predetermined cycle, and the k first charging units are turned off. The time is sequentially reduced to the first off time k times.
At this time, every m times, the voltage applied between the electrodes of the piezoelectric elements having print data among the m electrodes in each column is discharged for the first off time by the m discharge parts in synchronization with this OFF. , Up to the second level. Then, each time the applied voltage returns to the first level due to the turning on of the first charging unit after the first off time, a pull-out signal is applied between the electrodes of the piezoelectric element having print data.

On the other hand, in a piezoelectric element wired in a matrix of m rows and k columns, each of the other (k-1) piezoelectric elements in m rows connected to the piezoelectric element changed to the second level each time. Since the off time of the first charging unit that turns on and off in a predetermined cycle is longer than the first off time, the voltage applied between the electrodes is
From the second level to the first level at a rate of change in which ink is not ejected from the nozzle by pressurization of the pressurizing chamber by the second charging unit until the first charging unit is turned on after the discharge is stopped after the first off time. To do.

Further, the time division matrix drive circuit is
The first electrode is provided between the electrodes of the m piezoelectric elements in each row.
K first charging parts for applying a level voltage, and m discharging parts for changing the voltage applied between the electrodes of the k piezoelectric elements in each row to the second level by discharging.
A second charging unit that applies a voltage between the electrodes of each piezoelectric element at the predetermined change rate, a first timing control unit that turns on and off the second charging unit at a predetermined cycle, and the m discharge units. And a print data output section that causes the discharge operation by the above-mentioned discharge operation to be performed for the off time of the second charging section, and the k first charging sections are sequentially operated in synchronization with the turning on of the second charging section. A second timing control unit for
Each time the second charging unit is turned off, the voltage applied between the electrodes of the piezoelectric element having the print data among the m number of m in each row is changed by the discharging operation of the discharging unit during the off time.
The level is changed from the level to the second level, and the applied voltage is returned to the first level by the operation of the first charging unit to form the pull-back signal. ) The voltage applied between the electrodes of the above piezoelectric elements is
When the discharging operation of the discharging section is stopped, the second charging section changes from the second level to the first level at the predetermined change rate (claim 11).

According to this structure, the voltage application between the electrodes of the piezoelectric element by the second charging section is turned on and off at a predetermined cycle, and the k first charging sections are synchronized with the turning on of the second charging section. The parts are sequentially turned on over k times. At this time, every m times, the voltage applied between the electrodes of the piezoelectric elements having print data among the m pieces in each column is secondly charged by the m pieces of discharging parts in synchronization with the turning off of the second charging part. Is discharged for only off time
Change to the second level. Then, each time the applied voltage returns to the first level when the first charging unit is turned on, a pull-out signal is applied between the electrodes of the piezoelectric element having print data.

On the other hand, in the piezoelectric elements wired in a matrix of m rows and k columns, the other (k-1) piezoelectric elements of m rows connected to the piezoelectric element changed to the second level each time are connected. The voltage applied between the electrodes changes from the second level to the first level at a rate of change such that ink is not ejected from the nozzle due to the pressurization of the pressure chamber by the second charging unit.

Further, the time division matrix drive circuit is
The k pulling-out signal applying sections for applying the pulling-out signal between the electrodes of the m piezoelectric elements in each column, and the voltage applied between the electrodes of the k piezoelectric elements in each row are set to the above-mentioned values. M number of voltage holding units that hold 1 level, and the above k
A timing control unit for sequentially applying the pulling-out signal by the individual pulling-out signal applying units, and a holding operation by the m voltage holding units are performed for the application time of the pulling-out signal when there is no print data. Each time the pull-out signal is applied, the voltage applied between the electrodes of the piezoelectric element without the print data among the m pieces of the print data is applied by the voltage holding section. It is adapted to be held at the first level (claim 12).

According to this structure, the k-strike signal applying section sequentially applies k-strike signals between the electrodes of the m piezoelectric elements in each column k times. And each time,
The voltage applied between the electrodes of the piezoelectric elements having no print data among the m pieces is held at the first level, and the pull-out signal is applied between the electrodes of the piezoelectric elements having the print data.

Further, the above k pieces of the striking signal applying section are
It comprises a pulling-out signal generating unit that repeatedly generates the above-mentioned pulling-out signal, and k switch elements connected between the other electrode of the m piezoelectric elements in each column and the above-mentioned pulling-out signal generating unit. The timing control section sequentially turns on the k switch elements in synchronization with the generation of the pull-out signal (claim 13).

According to this structure, the k switching elements are sequentially turned on k times, and the pulling signal is applied between the electrodes of the m piezoelectric elements in each column from the pulling signal generation section. . Then, at each time, the voltage applied between the electrodes of the piezoelectric element having no print data is maintained at the first level among the m pieces, and the pull-out signal is applied between the electrodes of the piezoelectric element having the print data. .

Further, in an ink jet recording apparatus for ejecting ink onto a recording medium in accordance with print data from a plurality of nozzles arranged in an array on a recording head, one side wall of the plurality of pressurizing chambers communicating with each of the nozzles is formed. Piezoelectric element portions each provided to form a piezoelectric element that deforms when a drive voltage signal is applied and ejects ink from the nozzle, and the plurality of piezoelectric element portions that apply the drive voltage signal to the corresponding piezoelectric elements. And the driving voltage signal is sequentially shifted by at least the pulse width of the pulse current flowing into the piezoelectric element when the driving voltage signal is applied to at least a predetermined number of the piezoelectric elements among the plurality of piezoelectric elements. And a timing control means for applying the voltage at different timings (claim 14).

According to this structure, the drive voltage signal is applied to the piezoelectric element, the piezoelectric element is deformed to pressurize the pressure chamber, and ink is ejected from the nozzle. A pulse current flows through the piezoelectric element when the drive voltage signal is applied, but the drive voltage signal is applied to a predetermined number of piezoelectric elements at timings sequentially shifted by at least the pulse width of the pulse current. Therefore, when the predetermined number of piezoelectric elements are driven, the pulse currents do not flow at the same time, and the superposition of the pulse currents is reduced.

Further, the predetermined number is equal to the plurality (claim 15).

According to this structure, the drive voltage signal is applied to the piezoelectric element, the piezoelectric element is deformed to pressurize the pressure chamber, and ink is ejected from the nozzle. A pulse current flows through the piezoelectric element when the drive voltage signal is applied, but the drive voltage signal is applied to each piezoelectric element at timings sequentially shifted by at least the pulse width of the pulse current. Therefore, when driving each piezoelectric element, the pulse currents do not flow simultaneously, so that the pulse currents are not superimposed.

Further, the piezoelectric element section includes a plurality of groups each including the predetermined number of piezoelectric elements as a unit (claim 16).

According to this structure, the drive voltage signal is applied to the piezoelectric element, the piezoelectric element is deformed to pressurize the pressurizing chamber, and ink is ejected from the nozzle. A pulse current flows through the piezoelectric elements when the drive voltage signal is applied, but the drive voltage signal is applied to a predetermined number of piezoelectric elements forming each group at timings sequentially shifted by at least the pulse width of the pulse current. Therefore, only the same number of piezoelectric elements as groups are driven at the same time and the pulse currents are superimposed, and when driving the predetermined number of piezoelectric elements forming each group, the pulse currents do not flow at the same time, and the superposition of pulse currents is reduced. It

Further, in an ink jet recording apparatus for ejecting ink onto a recording medium corresponding to print data from a plurality of nozzles arranged in an array on a recording head, one side wall of the plurality of pressurizing chambers respectively communicating with the nozzles is provided. Piezoelectric elements that are respectively provided to be formed and that deform when a drive voltage signal having a predetermined pulse width is applied to eject ink from the nozzles are divided into a plurality of groups each including a predetermined number of the piezoelectric elements. At the same time, at least the above-mentioned piezoelectric elements of each divided group are divided into a plurality of sub-groups each consisting of a predetermined number of piezoelectric elements, and the piezoelectric elements in the divided groups are at least for each of the sub-groups. Driving of the number of divided groups that apply the drive voltage signal at timings sequentially shifted by the pulse width of the drive voltage signal And the drive voltage signal is applied to the piezoelectric elements of the corresponding sub-groups of each divided group at timings sequentially shifted by at least the pulse width of the pulse current flowing into the piezoelectric element when the drive voltage signal is applied. And a timing control means (claim 17).

According to this structure, the driving voltage signals are applied to the piezoelectric elements in each group at timings sequentially shifted by at least the pulse width of each sub group, and the piezoelectric elements in each group are provided with the corresponding sub elements. The drive voltage signal is applied to each group at a timing shifted by at least the pulse width of the pulse current flowing into the piezoelectric element when the drive voltage signal is applied. Therefore, only the piezoelectric elements forming the sub-group are driven at the same time so that the pulse currents are superimposed, and the pulse currents do not flow to the other piezoelectric elements at the same time.

The predetermined number of piezoelectric elements forming the group are wired in a matrix of a plurality of rows and columns, and the predetermined number of piezoelectric elements forming the sub-groups are arranged in the columns. It is a piezoelectric element to be constructed (claim 18).

According to this structure, the driving voltage signals are applied to the piezoelectric elements arranged in a matrix forming the groups at the timings sequentially shifted by at least the pulse width of each column, and the piezoelectric elements between the groups are applied. The drive voltage signal is applied to each of the corresponding columns at a timing shifted by at least the pulse width of the pulse current flowing into the piezoelectric element when the drive voltage signal is applied. Therefore, only the piezoelectric elements forming the column are simultaneously driven and the pulse currents are superimposed, and the pulse currents do not flow to the other piezoelectric elements at the same time, so that the superposition of the pulse currents is reduced.

[0057]

BEST MODE FOR CARRYING OUT THE INVENTION First, a first embodiment of an ink jet head drive device according to the present invention will be described with reference to FIGS. FIG. 1 is a perspective view showing an ink ejection portion of a recording head, FIG. 2 is a block diagram showing a configuration of an inkjet head driving device of the first embodiment, and FIG. 3 is a voltage at each point.
3 is a timing chart showing current and print data output from the print data output unit 2.

This ink jet head drive device ejects ink droplets from the ink ejection nozzles of the recording head of the ink jet recording device. As shown in FIG.
The timing control unit 101, the print data output unit 2, the piezoelectric element unit 3, and the drive circuit 4 are included.

As shown in FIG. 1, the recording head is provided with n ink ejecting sections 3-1 to 3-n arranged in an array, that is, in one row or in a plurality of rows, at a predetermined interval.
Each of the ink ejection portions 3-1 to 3-n includes ink chambers I1 to In (not shown) that stores ink, and an ink ejection nozzle N1 formed in communication with the ink chambers I1 to In.
To Nn and ink supply paths H1 to Hn. Piezoelectric elements Z1 to Zn sandwiched by a pair of electrodes (not shown) are arranged on one wall of each of the ink chambers I1 to In.

Then, the ink is supplied from the ink storage portion (not shown) to the ink chambers I1 to In through the ink supply paths H1 to Hn, and a piezoelectric element is driven by applying a drive voltage signal between both electrodes of each piezoelectric element. The ink chambers I1 to In are deformed to pressurize the ink chambers I1 to In, and ink droplets are ejected from the ink ejection nozzles N1 to Nn.

In the present embodiment, a pull-out signal is used as the drive voltage signal. That is, in a steady state, a voltage of a predetermined level is applied between the electrodes of the piezoelectric element to maintain the ink chamber in a pressurized state, and the applied voltage level is once reduced to relieve the pressurized state of the ink chamber. The applied voltage is rapidly increased to return to the above predetermined level, and the ink chamber is pressurized again. When the ink chamber is re-pressurized by the pull-out signal, an ink droplet is ejected from the ink ejection nozzle.

As shown in FIG. 2, the piezoelectric element section 3 comprises the piezoelectric elements Z1 to Zn. The drive circuit 4 includes charge / discharge circuits 4-1 to 4-n and transistors Q1 to Qn. The charge / discharge circuits and the transistors are connected in series via a piezoelectric element, and a drive voltage is applied to the piezoelectric elements Z1 to Zn. Is applied.

The charging / discharging circuits 4-1 to 4-n are respectively connected to the output terminals P11 to P1n of the timing control unit 101, and based on timing signals input from the timing control unit 101, A1 to S1 of FIG. It outputs a voltage having a predetermined waveform as indicated by An.

The collectors of the transistors Q1 to Qn are the piezoelectric elements Z1 to Zn, the base is the print data output unit 2, and
The emitters are respectively connected to the ground, and when turned on, one of the electrodes of the piezoelectric elements Z1 to Zn is connected to the ground line.

The print data output section 2 is, for example, print data P21 to P21 read by an image reading section including a photoelectric conversion element such as a CCD or a phototransistor and an image processing circuit.
2n is output in parallel to the bases of the transistors Q1 to Qn based on the timing signal input from the timing control unit 101. Here, when ejecting ink, the print data is a high level signal and the transistors Q1 to Qn are turned on. On the other hand, when ink is not ejected, the print data is a low level signal and the transistor Q
Turn off 1 to Qn. In addition, each print data P
21 to P2n are output from the print data output unit 2 at every predetermined ink ejection cycle. The print data output unit 2
May output print data input from an external device such as a personal computer.

The timing control unit 101 has an output terminal P1.
The timing signals are output to the charging / discharging circuits 4-1 to 4-n after being shifted by a predetermined time d described below in order from 1 to P1n to control the output timing of the drive voltage from the charging / discharging circuits 4-1 to 4-n. It is a thing. Further, a timing signal is output to the print data output unit 2 to output the print data P21 to P2n in synchronization with the output timing of the drive voltage of the charge / discharge circuits 4-1 to 4-n.

With the above configuration, when the print data P21 to P2n of the print data output section 2 are at a high level and the transistors Q1 to Qn are turned on, and one of the electrodes of the piezoelectric elements Z1 to Zn is connected to the ground, charging and discharging are performed. Drive voltages are applied to the piezoelectric elements Z1 to Zn by the output voltages of the circuits 4-1 to 4-n.

Next, an example of the operation will be described with reference to FIG. When the print data P21 is black and a high level signal is output, the transistor Q1 is turned on, and one electrode of the piezoelectric element Z1 is connected to the ground. Then, the drive voltage is applied to the piezoelectric element Z1 by the output voltage A1 from the charge / discharge circuit 4-1. At this time, the pulse current A′1 having the pulse width d flows through the piezoelectric element Z1.

Next, when the print data P22 is black and a high level signal is output, the transistor Q2 is turned on, and one electrode of the piezoelectric element Z2 is connected to the ground. And
A drive voltage is applied to the piezoelectric element Z2 by the output voltage A2 from the charging / discharging circuit 4-2 which is output from the charging / discharging circuit 4-1 by a predetermined time d. At this time, similarly, the pulse current A′2 having the pulse width d flows through the piezoelectric element Z2, but since the application of the drive voltage is deviated by the predetermined time d,
It is not superimposed on the pulse current A′1 of the piezoelectric element Z1.

Subsequently, when the print data P23 is black and a high level signal is output, the transistor Q3 is turned on, one electrode of the piezoelectric element Z3 is connected to the ground, and the charging / discharging circuit 4-3 continues for a predetermined time. A drive voltage is applied to the piezoelectric element Z3 by the voltage A3 that is output with a shift of d. At this time, similarly, the pulse current A′3 having the pulse width d flows through the piezoelectric element Z3, but since the application of the drive voltage is shifted by the predetermined time d, the pulse current A ′ of the piezoelectric element Z2.
It is not superimposed on 2.

Further, the print data P2n is output with a predetermined time difference of d, and the voltage A from the charge / discharge circuit 4-n is output.
When a driving voltage is applied to the piezoelectric element Zn by n, a pulse current A′n having a pulse width d flows through the piezoelectric element Zn.

As shown in the second cycle of the print data P22 in FIG. 3, when the print data is white and no signal is output, the transistor Q2 remains off and one electrode of the piezoelectric element Z2 is grounded. Not connected. Therefore, the piezoelectric element Z2 is controlled by the voltage A2 output from the charge / discharge circuit 4-2.
Since the drive voltage is not applied to the pulse current A2, the pulse current A'2 does not flow as shown in FIG.

As described above, since the drive voltage is applied to each of the piezoelectric elements Z1 to Zn by shifting by a predetermined time d equal to the pulse width of the pulse current, each of the piezoelectric elements Z1 to Zn can be applied.
The pulse currents flowing through are not superimposed. Therefore, the level of the inrush current flowing through the piezoelectric elements Z1 to Zn can be suppressed to a low level. Therefore, the noise level due to the pulse current can be reduced, and the charge / discharge circuits 4-1 to 4-n can be reduced.
The power supply capacity of can be reduced, and the size can be reduced.

In the above embodiment, the piezoelectric elements Z1 to Z1.
Although the drive voltage is applied to Zn by sequentially shifting by a predetermined time d, the piezoelectric elements Z1 to Zn are divided into a plurality of groups and the drive voltage is applied to the piezoelectric elements of each group by a predetermined time d. At the same time, the drive voltage may be applied in synchronization with the corresponding piezoelectric elements of each group. For example, the piezoelectric element corresponding to the nozzle in the center of the recording head is divided into two groups, and the piezoelectric element at one end of each group is synchronized with the piezoelectric element at the other end for a predetermined time d.
The drive voltage may be applied by shifting each. In this case, only two pulse currents are superposed, but further superposition of pulse currents is suppressed. Moreover, since the drive voltage is sequentially applied in synchronization with the piezoelectric elements of each group, the voltage application time can be shortened accordingly. Therefore, the ink ejection cycle can be shortened as compared with the above embodiment.

Next, a second embodiment of the ink jet head driving device according to the present invention will be described with reference to FIGS. FIG. 4 is a block diagram showing the configuration of the inkjet head driving device of the second embodiment. FIG. 5 is a timing chart showing the voltage signal at each point and the print data of the print data output unit B1. FIG. 6 is a timing chart showing an output voltage signal of each charge / discharge circuit and a pulse current flowing in each piezoelectric element.

The ink jet head driving device according to the second embodiment has a timing control section 101 and n print data output sections B1, B2, B3, ..., Piezoelectric element section C1.
C2, C3, ... And matrix drive circuits E1, E2, E
, And each of the parts has the same function as that of the first embodiment. In each of the piezoelectric element parts C1, C2, C3, ..., A plurality of piezoelectric elements are arranged in a matrix of a plurality of rows and columns. The piezoelectric elements are time-divisionally matrix-driven by driving them in a time-division manner for each column.

The piezoelectric element portion C1 is arranged in an array on the recording head, that is, m × k piezoelectric elements 111 to 11k, 121 provided on each of m × k ink discharge nozzles arranged in one row or a plurality of rows. ~ 12k, ..., 1m1-1
It consists of mk. The matrix driving circuit E1 includes a charging / discharging circuit F1 that outputs voltage signals S11 to S1k from respective output terminals.
And the transistors Q11 to Q1m, k output terminals of the charge / discharge circuit F1 and m transistors Q11 to Q.
1 m are arranged in a matrix so that a driving voltage can be applied to m × k piezoelectric elements of the piezoelectric element portion C1.

That is, the voltage signal S from the charging / discharging circuit F1.
11 is output to one electrode of each of the piezoelectric elements 111, 121, ..., 1m1, and the voltage signal S12 is output to the piezoelectric element 1
, 122m, ..., 1m2, respectively, and the voltage signal S1k is output to the piezoelectric element 1 in the same manner.
, 1 mk are output to one of the electrodes. Then, the charging / discharging circuit F1 outputs the voltage signals S11 to S1k having the same predetermined waveforms as those in the first embodiment based on the timing signal input from the output terminal T1 of the timing control unit 101 to the voltage signal S11 in FIG. , S1
2, S1k are sequentially shifted and output at timings where they do not overlap.

The transistor Q11 has a collector connected to the piezoelectric elements 111 to 11k, a base connected to the output terminal of the print data output section B1, and an emitter connected to the ground. The collector of the transistor Q12 is the piezoelectric element 121.
Up to 12k, the base is connected to the output terminal of the print data output unit 2, and the emitter is connected to the ground. Similarly, in the transistor Q1m, the collector is connected to the piezoelectric elements 1m1 to 1mk, the base is connected to the output terminal of the print data output unit 2, and the emitter is connected to the ground. When each transistor is turned on, one electrode of each piezoelectric element is connected to the ground line.

The print data output section B1 outputs transistors Q11 to Q1m from the output terminals according to the timing signal input from the output terminal U1 of the timing control section 101.
The print data D11 to D1m are simultaneously output to the base in parallel in parallel, and k print data are serially output from the respective output terminals.

The piezoelectric element portions C2, C3, ... Are connected to the piezoelectric element portion C1 and the matrix drive circuits E2, E3 ,.
Matrix drive circuit E1 and print data output sections B2, B
.. have the same configuration as the print data output unit B1.

The timing control unit 101 has an output terminal T
1, T2, T3, ... are sequentially shifted by a predetermined time d, and timing signals are output to the charging / discharging circuits F1, F2, F3, ..., The driving voltage output timing from the charging / discharging circuits F1, F2, F3 ,. It is to shift by a predetermined time d.
In addition, the timing control unit 101 uses the output terminals U1, U
2, U3, ... to print data output units B1, B2, B3
A timing signal is output to, and the print data is output from the output terminals of the print data output unit to the charging / discharging circuits F1, F2, F3.
The output voltage is output in synchronization with the output timing of the driving voltage.

Next, the operation of the matrix drive circuit E1 will be described with reference to FIG. The voltage signals S11 to S1k having a predetermined waveform are output from the respective output terminals of the charging / discharging circuit F1 at timings that do not overlap in order.

On the other hand, from the print data output section B1, first,
The print data corresponding to the piezoelectric elements 111, 121, ..., 1m1 are simultaneously output in parallel in synchronization with the output timing of the voltage signal S11. That is, in FIG. 5, black signals are output as the print data D11 and D1m, and white signals are output as the print data D12. Therefore, the piezoelectric element 11
A driving voltage is applied to 1, 1 m1, ink is ejected, and a driving voltage is not applied to the piezoelectric element 121.
No ink is ejected.

Next, the print data output section B1 outputs the print data corresponding to the piezoelectric elements 112, 122, ..., 1m2 simultaneously in parallel in synchronization with the output timing of the voltage signal S12. That is, in FIG. 5, the print data D11 and D12 are black signals, and the print data D1m are white signals.
It is output respectively. Therefore, a drive voltage is applied to the piezoelectric element 112, and ink is ejected. Although not shown, a drive voltage is applied to the piezoelectric element 112 and ink is ejected, and a drive voltage is not applied to the piezoelectric element 1m2 and ink is not ejected.

Similarly, the print data corresponding to each piezoelectric element is simultaneously output in parallel from each output terminal of the print data output section B1 in synchronization with the output timing of the drive voltage of the charging / discharging circuit F1.

The print data output section B1 outputs the k-th print data corresponding to the piezoelectric elements 11k, 12k, ..., 1mk in parallel in parallel with the output timing of the voltage signal S1k. That is, in FIG. 5, a white signal is output as the print data D11, and a black signal is output as the print data D12 and D1m. Therefore, the piezoelectric element 1
No drive voltage is applied to 1k, and ink is not ejected. Although not shown, a drive voltage is applied to the piezoelectric elements 12k and 1mk, and ink is ejected.

The voltage signal S11 of the charging / discharging circuit F1 is
The output is repeated in a predetermined ink discharge cycle, and the above operation is repeated in the ink discharge cycle.

In this way, the voltage signal S of the charging / discharging circuit F1 is
11 to S1k are sequentially output at timings that do not overlap, and transistors Q11 to Q corresponding to print data are output.
By controlling ON / OFF of 1 m, a drive voltage can be applied to m × k piezoelectric elements.

The matrix drive circuits E2, E3,
Also in ..., The same operation as the matrix drive circuit E1 is performed.

Next, the operation timing of each matrix drive circuit E1, E2, E3, ... Will be described with reference to FIG.

The output terminal T1 of the timing control unit 101
Based on the timing signals from T2, T3, ..., Predetermined voltage signals are output from the charging / discharging circuits F1, F2, F3 ,. That is, the voltage signal S1
, S21, S31, ... Are output with a predetermined time difference d, and the voltage signals S12, S22, S32 ,.
The voltage signals S1 and
, k, S2k, S3k, ... Are output with a delay of a predetermined time d.

In this way, each matrix drive circuit E1,
Since the drive voltage is applied to the piezoelectric elements corresponding to E2, E3, ... while being shifted by a predetermined time d that is equal to the pulse width of the pulse current flowing through the piezoelectric elements, the pulse currents flowing through the respective piezoelectric elements are superimposed. Can be reduced.
Therefore, it is possible to suppress an increase in the peak current of the pulse current. Therefore, the noise level due to the pulse current can be reduced and the power supply capacity of the charging / discharging circuits F1 to Fn can be reduced, and the size thereof can be reduced.

Next, the procedure for determining the number n of matrix drive circuits, the number k of output terminals of each charging / discharging circuit, and the number m of output terminals of each print data output section will be described by taking the case where the number of nozzles is 2000 as an example. To do.

First, the number of pulse widths of the pulse current flowing through the piezoelectric element can be taken in one period of the ink ejection cycle set by the performance of the piezoelectric element, that is, the number n'which can be shifted by each pulse width. calculate. This n '
When the ink ejection frequency is n0 (kHz) and the pulse width of the pulse current flowing through the piezoelectric element is d (sec), n '= 1 /
It is calculated by (n0 × d). For example, d = 10μse
c. As in the conventional example, if n0 = 5 kHz, then n '= 20.

On the other hand, the number k of output terminals of each charging / discharging circuit is determined by how many times the drive voltages can be output without overlapping the driving voltage in one ink discharge cycle. That is, if the pulse width of the drive voltage waveform is λ (sec), k = 1 / (n0 × λ)
Thus, the number of output terminals of each charge / discharge circuit is obtained. It should be noted that the numbers below the decimal point may be discarded. For example, if λ = 50 μsec as in the conventional example, k = 4.

Therefore, the number n of matrix drive circuits is calculated by n = n '/ k since the piezoelectric elements are driven by shifting the pulse width of the pulse current for each matrix drive circuit. In the above example, n = 5.

From the above, if the number of nozzles is 2000, 1
The number of piezoelectric elements per matrix drive circuit is 2000/5 = 40
Since it becomes 0, m = 400 / k = 100. Therefore, the maximum number of piezoelectric elements that can be simultaneously driven is 100, which can be reduced compared to 500 in the conventional example.

Next, a third embodiment of the ink jet head driving device according to the present invention will be described with reference to FIGS. 7 and 8. FIG. 7 is a circuit block diagram showing the configuration of the third embodiment, and FIG. 8 is a timing chart showing the operating state and voltage of each part of FIG.

The ink jet head driving apparatus of the third embodiment comprises a timing control section 1, a print data output section 2, a piezoelectric element section and a charging / discharging section, and ejects ink droplets from the nozzles of the recording head onto recording paper. The image is printed.

The following embodiments are examples of a circuit configuration in which a plurality of piezoelectric elements are wired in a matrix of a plurality of rows and columns, and each piezoelectric element is time-divisionally driven for each column. Is shown. The circuit shown in the following embodiment is applied to each piezoelectric element portion C1 of the second embodiment.
It can also be applied to C2, C3, ....

The piezoelectric elements are arranged in an array on the recording head, that is, piezoelectric elements Z11 to Z1k, Z21 provided in m × k nozzles arranged in one row or in a plurality of rows.
, Z2k, ..., Zm1 to Zmk, each piezoelectric element is disposed on one side wall of the pressurizing chamber, and is deformed by applying a pulling-out signal between both electrodes to pressurize the pressurizing chamber. The ink droplets are ejected from the. Piezoelectric element Z1
1 to Z1k, Z21 to Z2k, ..., Zm1 to Zmk are
One of the electrodes is commonly grounded.

The charging / discharging section is composed of a power supply 30 of voltage V0, segment transistors Q11 to Q1k, data transistors Q21 to Q2m, etc. Each transistor is connected to the other electrode of the piezoelectric element via a resistor and a diode, respectively. , And applies a striking signal between the electrodes of the piezoelectric element.

In the segment transistor Q11, the emitter is connected to the power supply 30, and the base is the timing control unit 1.
Of the piezoelectric element Z1 connected to the output terminal T1 of
1, Z21, ..., Zm1 are respectively connected via a series circuit of a resistor R1 and a forward diode D1. Further, the segment transistors Q12 to Q1k have the same circuit configuration, and their emitters are connected to the power source 30,
The base is connected to the output terminals T2 to Tk of the timing control unit 1, and the collector is connected to each piezoelectric element via a series circuit of a resistor R1 and a forward diode D1.

The collector of the data transistor Q21 is connected to the piezoelectric elements Z11, Z12, ...
2 and the reverse diode D2 are connected through a series circuit, the base is connected to the output terminal P1 of the print data output unit 2, and the emitter is grounded. Further, the data transistors Q22 to Q2m also have the same circuit configuration, and the collectors of the respective piezoelectric elements are the resistors R2 and the reverse diodes D.
2 are connected via a series circuit, the bases are connected to the output terminals P2 to Pm of the print data output unit 2, and the emitters are grounded.

The print data output unit 2 receives, as a pulse signal having a predetermined pulse width, print data read by an image reading unit including a photoelectric conversion element such as a CCD or a phototransistor, as a timing signal input from the timing control unit 1. Accordingly, the output terminals P1 to Pm simultaneously output in parallel to the bases of the data transistors Q21 to Q2m. Further, k print data is serially output from each output terminal in accordance with the timing signal input from the timing control section 1.

Then, on / off of the data transistors Q21 to Q2m is controlled by the output print data.
Here, when ejecting ink, the data transistors Q21 to Q2m are turned on. On the other hand, when the ink is not ejected, the data transistors Q21 to Q2m are kept off. The print data output unit 2 may output print data input from an external device such as a personal computer.

The timing control section 1 sequentially outputs high level signals having a predetermined pulse width from the output terminals T1 to Tk in synchronization with the serial output of the print data output section 2, and turns off the segment transistors Q11 to Q1k in order. In the steady state, a low level signal is output from each output terminal to keep each segment transistor on, thereby dynamically scanning the segment transistors Q11 to Q1k.

With the above configuration, in the steady state, the segment transistors Q11 to Q1k have the timing control unit 1
The ON state is maintained by the low-level signal from, and the voltage V0 is applied to each connected piezoelectric element.

Then, each segment transistor Q11
Up to Q1k are sequentially turned off by a predetermined pulse width by a high level signal input from the timing control unit 1. On the other hand, each data transistor Q21 to Q2m
Is turned on by a predetermined pulse width according to the print data output from the print data output unit 2. Therefore, the application of the voltage V0 to each piezoelectric element is stopped, and the electric charges of each piezoelectric element connected to each other are applied to the resistor R2 and the diode D2.
, The voltage applied to each piezoelectric element decreases. Next, when the segment transistors Q11 to Q1k are turned on and the data transistors Q21 to Q2m are turned off, the voltage applied to each piezoelectric element suddenly rises to the voltage V0 of the power supply 30. Ink droplets are ejected from the nozzles of each piezoelectric element when the applied voltage suddenly rises, by the pulling-out signal formed by the drop and sudden rise of the applied voltage to each piezoelectric element.

For example, when the data transistors Q21 to Q2m are turned on in synchronization with the turning off of the segment transistor Q11, the piezoelectric elements Z11 to Zm1 are discharged through the series circuit of the resistor R2 and the diode D2 and applied to each piezoelectric element. The voltage drops to voltage V1. Next, when the data transistors Q21 to Q2m are turned off in synchronization with the turning on of the segment transistor Q11, the piezoelectric element Z11
~ Discharging of Zm1 is stopped and each piezoelectric element is supplied with power 3
When the voltage V0 of 0 is applied, the voltage applied to each piezoelectric element suddenly increases from the voltage V1 to the voltage V0, and the piezoelectric elements Z11 to Z11.
Ink droplets are ejected from the nozzle m1.

Here, when the segment transistor Q11 is off, the segment transistors Q12 to Q1k.
Is turned on. At this time, the data transistor Q
When 21 to Q2m are turned on, the piezoelectric elements connected to the segment transistors Q12 to Q1k are discharged through the series circuit of the resistor R2 and the diode D2, but since the application of the voltage V0 is continued, each piezoelectric element is discharged. The voltage applied to the element becomes a divided voltage V2 obtained by dividing the voltage V0 by the resistors R1 and R2.

Then, the data transistors Q21 to Q2
When m is turned off, the applied voltage to each piezoelectric element is the divided voltage V
The voltage rises sharply from 1 to the voltage V0, but it is necessary to prevent ink droplets from being ejected during this sharp rise. Therefore, the resistance R
The values of 1 and R2 are such that the voltage applied to the piezoelectric element is the divided voltage V1.
Is set to a value that does not cause ink droplets to be ejected even when the voltage suddenly rises to V0.

Next, the operation of the piezoelectric elements Z11, Z12, Z1k will be described with reference to FIG. Initially, each data transistor is off, each segment transistor is on, and the voltage V0 is applied to each piezoelectric element.

First, the segment transistor Q11 is turned off. In synchronization with this OFF, the data transistor Q2 is generated by the print data corresponding to the nozzle of the piezoelectric element Z11.
1 is turned on, the application of the voltage V0 to the piezoelectric element Z11 is stopped and the piezoelectric element Z11 is discharged, and the applied voltage V11 to the piezoelectric element Z11 is reduced to the voltage V1. On the other hand, when the data transistor Q21 is turned on, the piezoelectric elements Z12 and Z1 are
Since k also discharges, the applied voltages V12 and V1k also decrease, but since the segment transistors Q12 and Q1k are turned on and the voltage V0 continues to be applied, the applied voltage V
12, V1k drops to the divided voltage V2 (> V1).

When the segment transistor Q11 is turned on and the data transistor Q21 is turned off, the discharge of the piezoelectric element Z11 is stopped and the voltage V0 is applied, so that the voltage V11 applied to the piezoelectric element Z11 is the voltage V0.
And the voltage (V0-V1) is applied, and ink droplets are ejected from the nozzle of the piezoelectric element Z11. on the other hand,
Since the discharge of the piezoelectric elements Z12 and Z1k is stopped, the applied voltages V12 and V1k rise to the voltage V0 and the voltage (V0−
V2) is applied. However, this voltage (V0-V2)
Since the deformation amount of the piezoelectric element is set to a value that does not reach ink ejection, ink droplets are not ejected from the nozzles of the piezoelectric elements Z12 and Z1k.

Then, the segment transistor Q12 is turned off. In synchronization with this OFF, the data transistor Q2
1 is turned on, the application of the voltage V0 to the piezoelectric element Z12 is stopped and the piezoelectric element Z12 is discharged, and the applied voltage V12 to the piezoelectric element Z12 drops to the voltage V1. On the other hand, when the data transistor Q21 is turned on, the piezoelectric elements Z11 and Z1k are also discharged, so that the applied voltages V11 and V1k thereof are also reduced. However, the segment transistors Q11, Q1k
Since the voltage is ON and the voltage V0 is continuously applied, the applied voltages V11 and V1k decrease to the divided voltage V2.

When the segment transistor Q12 is turned on and the data transistor Q21 is turned off, the discharge of the piezoelectric element Z12 is stopped and the voltage V0 is applied, and the applied voltage V12 rapidly rises to the voltage V0 and the voltage (V0 -V1) is applied, and ink droplets are ejected from the nozzle of the piezoelectric element Z12. On the other hand, the piezoelectric elements Z11, Z
Since the discharge of 1k is stopped, the applied voltages V11 and V1k rise to the voltage V0 and the voltage (V0-V2) is applied, but ink droplets are not ejected from the nozzles of the piezoelectric elements Z11 and Z1k.

Similarly, the segment transistor Q1
k is turned off, the data transistor Q21 is turned on by the print data corresponding to the nozzle of the piezoelectric element Z1k in synchronism with this off, ink droplets are ejected from the nozzle of the piezoelectric element Z1k, and the piezoelectric elements Z11 and Z12 are ejected. No ink droplets are ejected from the nozzle.

In this way, the voltage drop applied to the piezoelectric element of the nozzle that does not correspond to the print data is made small so that the deformation amount of the piezoelectric element becomes a level at which the ink drop is not ejected due to the surface tension of the ink. It is possible to control the ejection and non-ejection of ink droplets from each nozzle.

Therefore, the structure of the piezoelectric element section can be simplified by grounding one electrode of each piezoelectric element in common. Moreover, since the ejection driving can be adopted as the driving method of the piezoelectric element, high ink ejection performance can be obtained. Further, m × k piezoelectric elements can be driven by time-division matrix driving.

Although FIG. 7 shows an example in which the power source 30 is provided corresponding to each segment transistor for convenience of explanation, the same effect can be obtained even if the power source 30 is commonly provided.

Next, an example in which the circuit configuration of the third embodiment is slightly modified will be described with reference to FIGS. FIG. 9 is a circuit block diagram showing the configuration of the first modification of the third embodiment. FIG. 10 is a timing chart showing operating states and voltages of the respective parts of FIG.

In the circuit of FIG. 9, direct connection is made instead of the resistor R1 of FIG. 7, and the electrodes of each piezoelectric element and the diode D1 are connected.
A current limiting resistor R3 is inserted between the cathodes of the above.
With this configuration, for example, the segment transistor Q
When 12 is on, the voltage V0 of the power supply 30 is applied to the piezoelectric element Z12 even when the data transistor Q21 is on.

The operation of the piezoelectric elements Z11, Z12, Z1k will be described with reference to FIG. Initially, as in the case of FIG. 8, each data transistor is off, each segment transistor is on, and the voltage V0 is applied to each piezoelectric element.

First, the segment transistor Q11 is turned off. In synchronization with this OFF, the data transistor Q21
Is turned on, the application of the voltage V0 to the piezoelectric element Z11 is stopped and the piezoelectric element Z11 is discharged, and the applied voltage V11 to the piezoelectric element Z11 decreases to the voltage V1. On the other hand, when the data transistor Q21 is turned on, the piezoelectric elements Z12 and Z1k are also discharged, but since the segment transistors Q12 and Q1k remain on, the voltage V1 applied by the power supply 30 is applied.
2, V1k is maintained at the voltage V0.

When the segment transistor Q11 is turned on and the data transistor Q21 is turned off, the discharge of the piezoelectric element Z11 is stopped and the voltage V0 is applied, and the voltage V11 applied to the piezoelectric element Z11 is the voltage V0.
And the voltage (V0-V1) is applied, and ink droplets are ejected from the nozzle of the piezoelectric element Z11. on the other hand,
Applied voltage V12, V1k to the piezoelectric elements Z12, Z1k
Since the voltage V0 remains unchanged, the piezoelectric element Z12,
No ink droplet is ejected from the Z1k nozzle.

Hereinafter, the segment transistors Q12, Q
The same operation is performed when 1k is turned on, and ink droplets are ejected from the nozzles of the piezoelectric elements Z12 and Z1k, respectively.

As described above, by directly connecting instead of the resistor R1, the voltage applied to the piezoelectric element of the nozzle that does not correspond to the print data is maintained at the voltage V0 of the power supply 30, thereby controlling the ejection and non-ejection of ink. can do. Therefore, the same effect as in the case of FIG. 7 is obtained.

FIG. 11 is a circuit block diagram showing the configuration of the second modification of the third embodiment. FIG. 12 is a timing chart showing operating states and voltages of the respective parts of FIG.

In the circuit of FIG. 11, in addition to the circuit of FIG.
The resistor R4 is provided. The resistor R4 is connected between the electrode of each piezoelectric element, which is not grounded, and the power source 30, and pulls up the electrode. Further, the timing control unit 1 also turns off the dynamic scanning of OFF to be performed on the segment transistors Q11 to Q1k even during non-scanning, and sets the OFF pulse width of the data transistors Q21 to Q2m to ON as shown in FIG. Longer than the pulse width of. Note that the OFF pulse width during scanning is the same as the ON pulse width of the data transistors Q21 to Q2m, as in the third embodiment.

With the above structure, the timing of turning on the segment transistors Q11 to Q1k, that is, the timing of starting the rise of the voltage applied to each piezoelectric element is delayed during non-scanning. On the other hand, the data transistors Q21 to Q
The voltage applied to each piezoelectric element is increasing through the resistor R4 from the time when 2 m is turned off, and when the segment transistors Q11 to Q1k are turned on, the voltage V3 (> V
It is 1).

Therefore, since the rate of increase of the voltage applied to each piezoelectric element during non-scan becomes gentle as a whole, the pressurizing chamber is gradually pressurized by the deformation of the piezoelectric element, so that the surface tension of the ink is counteracted. As a result, the pressing force sufficient to eject the ink droplet cannot be obtained, and the ink droplet is not ejected.

The resistance value of the resistor R4 is set to such a value that the voltage applied to the piezoelectric element gradually increases from the voltage V1 to the voltage V3 so that ink droplets are not ejected from the nozzle.

Next, the operation of the piezoelectric elements Z11, Z12, Z1k will be described with reference to FIG. First, Fig. 8
As in the case of, each data transistor is off, each segment transistor is on, and the voltage V0 is applied to each piezoelectric element.

First, the segment transistors Q11, Q
12, Q1k is turned off. In synchronization with this OFF, the data transistor Q21 is turned on by the print data corresponding to the nozzle of the piezoelectric element Z11, and the piezoelectric elements Z11, Z
When the voltage V0 is stopped from being applied to the piezoelectric elements Z11, Z12, and Z1k, the voltage V0 is not applied to the piezoelectric elements Z11, Z12, and Z1k.
11, V12, and V1k drop to the voltage V1.

Then, the segment transistor Q11 is turned on, the data transistor Q21 is turned off, the discharge of the piezoelectric element Z11 is stopped, and the voltage V0 is applied, so that the applied voltage V11 to the piezoelectric element Z11 is the voltage V0.
And the voltage (V0-V1) is applied, and ink droplets are ejected from the nozzle of the piezoelectric element Z11.

On the other hand, when the data transistor Q21 is turned off, the piezoelectric elements Z12 and Z1k are also stopped from discharging, but since the segment transistors Q12 and Q1k remain off, the applied voltages V12 and V1 to the piezoelectric elements Z12 and Z1k are maintained.
k is gradually increased by the power supply 30 via the resistor R4 and becomes the voltage V3 when the segment transistors Q12 and Q1k are turned on. And the segment transistor Q1
2, the applied voltages V12 and V1k rise to the voltage V0 by turning on, but the rate of increase of the applied voltages V12 and V1k becomes gentle as a whole, so that the piezoelectric elements Z12 and Z1.
No ink droplet is ejected from the k nozzle.

Hereinafter, the segment transistors Q12, Q
The same operation is performed during 1k scanning, and ink droplets are ejected from the nozzles of the piezoelectric elements Z12 and Z1k, respectively, and ink droplets are not ejected from other piezoelectric elements.

As described above, since the other electrode of each piezoelectric element is pulled up to the power source 30 by the resistor R4 and the segment transistors Q11 to Q1k are turned off for a longer period of time even when the scanning is not performed, the non-scanning is performed. Since the voltage applied to the piezoelectric element gradually increases, it is possible to control the ejection and non-ejection of ink. Therefore, the same effect as in the case of FIG. 7 is obtained.

FIG. 13 is a circuit block diagram showing the structure of the third modification of the third embodiment. FIG. 14 is a timing chart showing operating states and voltages of the respective parts in FIG.

In the circuit of FIG. 13, in addition to the circuit of FIG.
The charging / discharging unit further includes a power supply 40 having a voltage V0, a common transistor Q0, and the like. The common transistor Q0 has an emitter connected to the power supply 40 and a base at the timing control unit 1.
Is connected to the output terminal T0 of each of the piezoelectric elements and the collector is connected to each piezoelectric element via a series circuit of a resistor R5 and a forward diode D3. The resistance value of the resistor R5 is such that when the segment transistor is off and the common transistor Q0 is on, the voltage applied to the piezoelectric element rises from the voltage V1 at a gradual increase rate such that ink droplets are not ejected from the nozzle. Is set to. That is, since the voltage applied to the piezoelectric element gradually rises, the ink is not ejected due to the surface tension of the ink in the pressurization of the pressure chamber due to the deformation of the piezoelectric element at this time.

With the above configuration, even when the data transistor is turned on and the voltage applied between the electrodes of the piezoelectric element drops to the voltage V1, the rate of increase of the applied voltage is gentle when the segment transistor is off and no scanning is performed. To
No ink droplet is ejected from the nozzle.

Next, the operation of the piezoelectric elements Z11, Z12, Z1k will be described with reference to FIG. Initially, each data transistor and each segment transistor are off, the common transistor Q0 is on, and the voltage V0 is applied to each piezoelectric element by the power supply 40.

First, the common transistor Q0 is turned off, the data transistor Q21 is turned on by the print data corresponding to the nozzle of the piezoelectric element Z11 in synchronization with this off, and the voltage V to the piezoelectric elements Z11, Z12, Z1k is turned on.
When the application of 0 is stopped and it is discharged, the piezoelectric element Z11,
The applied voltages V11, V12, V1k to Z12, Z1k decrease to the voltage V1.

Then, the common transistor Q0 and the segment transistor Q11 are turned on, the data transistor Q21 is turned off, the discharge of the piezoelectric element Z11 is stopped, the voltage V0 is applied, and the applied voltage V11 to the piezoelectric element Z11 is changed. The voltage suddenly rises to V0, and the voltage (V0-
V1) is applied and ink droplets are ejected from the nozzle of the piezoelectric element Z11.

On the other hand, the discharge of the piezoelectric elements Z12 and Z1k is stopped by turning off the data transistor Q21, but since the segment transistors Q12 and Q1k remain off, the applied voltages V12 and V1 of the piezoelectric elements Z12 and Z1k are kept.
k is the voltage V gradually increased by the power source 40 via the resistor R5.
Rises to zero. However, this applied voltage V12, V1k
Ink drops are not ejected from the nozzles of the piezoelectric elements Z12 and Z1k because of the gradual increase rate.

Hereinafter, the segment transistors Q12, Q
The same operation is performed during 1k scanning, and ink droplets are ejected from the nozzles of the piezoelectric elements Z12 and Z1k, respectively, and ink droplets are not ejected from other piezoelectric elements.

As described above, the power source 40 and the common transistor Q0 are provided, and the segment transistors Q11 to Q1k are provided.
During non-scanning, since the voltage applied to the piezoelectric element is gradually increased by the power source 40 via the resistor R5, ink ejection and non-ejection can be controlled. Therefore, the same effect as in the case of FIG. 7 is obtained.

Next, a fourth embodiment of the ink jet head driving device according to the present invention will be described with reference to FIGS. 15 and 16. FIG. 15 is a circuit block diagram showing the configuration of the inkjet head driving device of the fourth embodiment. FIG.
6 is a timing chart showing the operating state and voltage of each part of FIG.

Like the third embodiment, the fourth embodiment is composed of the timing control section 1, the print data output section 2, the piezoelectric element section, and the charging / discharging section. Two paths are provided, and the voltage applied to the piezoelectric element is reduced to a level required for ink ejection only when a discharge current flows through both paths.

The charging / discharging section includes a power source 30 having a voltage V0, a common transistor Q30, and segment transistors Q31 to Q31.
3k and data transistors Q21 to Q2m, etc., and each transistor is connected to the other electrode of the piezoelectric element via a resistor and a diode, respectively, and applies a strike signal between the electrodes of the piezoelectric element.

The segment transistor Q31 is an NPN.
, The base is connected to the output terminal U1 of the timing control unit 1, the emitter is grounded, and the collector is connected to the piezoelectric elements Z11, Z21, ..., Zm1 via the series circuit of the resistor R6 and the reverse diode D4, respectively. Has been done. NPN type segment transistors Q32 to Q3k
Also in the same circuit configuration, the base is connected to the output terminals U2 to Uk of the timing control unit 1, the emitter is grounded, and the collector is connected to each piezoelectric element via the series circuit of the resistor R6 and the reverse diode D4. It is connected.

The common transistor Q30 is a PNP type,
The base is connected to the output terminal U0 of the timing control unit 1, the emitter is connected to the power supply 30, and the collector is connected to all the piezoelectric elements via the series circuit of the resistor R1 and the forward diode D1.

The timing control section 1 outputs a timing signal in synchronization with the common transistor Q30 and the print data output section 2, and turns on / off the common transistor Q30 in synchronization with the serial print data output from the print data output section 2. Let At this time, for example, the transistor Q2 in FIG.
As shown in the timing chart of No. 1, each data transistor is turned on by each print data in synchronization with the turning off of the common transistor Q30.

Further, the timing control section 1 sequentially outputs a high level signal having a predetermined pulse width from the output terminals U1 to Uk in synchronization with the timing signal output to the common transistor Q30 and the print data output section 2, and FIG. As shown, the segment transistors Q31 to Q3k are sequentially turned on in synchronization with the off time of the common transistor Q30 to perform a dynamic scan.

With the above configuration, the common transistor Q3
When 0 is on, voltage V0 is applied between the electrodes of each piezoelectric element. When the data transistors Q21 to Q2m are turned on by the print data from the print data output unit 2, the connected piezoelectric elements are connected to the diode D2 and the resistor R.
It is discharged to the ground via 2 and the voltage applied between the electrodes of each piezoelectric element decreases from the voltage V0 to the voltage V4 determined by the resistance value of the resistor R2. In addition, each segment transistor Q
When 31 to Q3k are turned on by the timing signal input from the timing controller 1, each connected piezoelectric element is discharged to the ground via the diode D4 and the resistor R6, and the applied voltage changes from the voltage V0 to the resistor R6. The voltage drops to V5 which is determined by the resistance value. The voltage applied between the electrodes of the piezoelectric element drops to the voltage V1 only when both the segment transistor and the data transistor connected to each other are on.

The resistance values of the resistors R2 and R6 are such that the voltage applied between the electrodes of the piezoelectric element is from the voltage V4 to the voltage V0.
The value is set so that the ink droplets are not ejected from the nozzle due to the deformation of the piezoelectric element when returning to.

Next, the piezoelectric elements Z11, Z12, Z1k,
The operation of Zm1 will be described with reference to FIG. The common transistor Q30 of the timing control section 1 is turned on and off, and application and stop of the voltage V0 to each piezoelectric element are repeated. However, each data transistor and each segment transistor are turned off, and the voltage applied to each piezoelectric element is maintained at the voltage V0.

First, the common transistor Q30 is turned off, and in synchronization with this off, the data transistor Q21 is turned on and the segment transistor Q31 is turned on by the print data corresponding to the nozzle of the piezoelectric element Z11. As a result, the voltage V0 to the piezoelectric element Z11 is
Of the resistance R from the piezoelectric element Z11
Discharge occurs through two paths of R2 and R6, and the applied voltage V11 drops to the voltage V1.

On the other hand, when the data transistor Q21 is turned on, the piezoelectric elements Z12 and Z1k are also discharged, and the applied voltages V12 and V1k thereof are also reduced, but the segment transistors Q32 and Q3k are turned off.
Since the discharge is performed only from the path of the resistor R2, the applied voltages V12 and V1k drop to the voltage V4 (> V1).

Then, the common transistor Q30 is turned on, and in synchronization with this, the data transistor Q21 and the segment transistor Q31 are turned off. As a result, the discharge of the piezoelectric element Z11 is stopped, the voltage V0 is applied, the applied voltage V11 rapidly rises to the voltage V0, and the voltage (V0-V1) is applied to the piezoelectric element Z1.
Ink droplets are ejected from the first nozzle.

Further, the discharge of the piezoelectric elements Z12 and Z1k is stopped, the applied voltages V12 and V1k rise to the voltage V0,
A voltage (V0-V4) is applied between the electrodes of the piezoelectric elements Z12 and Z1k.
Is applied. However, since the voltage (V0-V4) is set to a value such that the deformation amount of the piezoelectric element does not reach the ink ejection, ink droplets are not ejected from the nozzles of the piezoelectric elements Z12 and Z1k.

Next, the common transistor Q30 is turned off, and the data transistor Q21 is turned on and the segment transistor Q32 is turned on by the print data corresponding to the nozzles of the piezoelectric element Z12 in synchronization with this off.

Accordingly, the voltage V applied to the piezoelectric element Z12
When the application of 0 is stopped, the piezoelectric element Z12 becomes resistive R
Discharge occurs through two paths of R2 and R6, and the applied voltage V12 drops to the voltage V1. On the other hand, segment transistor Q3
1, Q3k is off, so the piezoelectric element Z11,
Since Z1k discharges only through the path of the resistor R2, the applied voltages V11 and V1k drop to the voltage V4.

Therefore, by the action similar to the above, ink droplets are ejected only from the nozzle of the piezoelectric element Z12.

On the other hand, the segment transistor Q3k,
When the segment transistors Q31 and Q32 are turned on in the next cycle, there is no print data corresponding to the nozzles of the piezoelectric elements Z1k, Z11 and Z12, and there is no data transistor Q.
21 remains off. Therefore, the piezoelectric elements Z1k, Z
Since 11, 11 and 12 are discharged only from the path of the resistor R6, the applied voltages V1k, V11, and V12 decrease to the voltage V5. After that, the common transistor Q30 is turned on, the applied voltages V1k, V11, V12 rise to the voltage V0, and the voltage (V0-V5) is applied between the electrodes of the piezoelectric elements Z1k, Z11, Z12. However, the voltage (V0-V
In 5), the amount of deformation of the piezoelectric element is set to a value that does not reach ink ejection, so ink droplets are not ejected from the nozzles of the piezoelectric elements Z1k, Z11, and Z12.

Further, when the segment transistor Q3k is turned on in the next cycle, the data transistor Q21 is turned on by the print data corresponding to the nozzle of the piezoelectric element Z1k. Therefore, the piezoelectric element Z1k has resistances R2 and R6.
Since the discharge is performed through the two paths, the applied voltage V1k decreases to the voltage V1. After that, the common transistor Q30 is turned on, the applied voltage V1k rises to the voltage V0, the voltage (V0-V1) is applied between the electrodes of the piezoelectric element Z1k, and the ink droplet is ejected from the nozzle of the piezoelectric element Z1k.

As described above, the fourth embodiment is provided with the two discharge paths of the data transistor which is turned on and off by the print data and the segment transistor which is turned on and off by the dynamic scan, and is discharged from both paths. Only when the voltage applied to the piezoelectric element is reduced to the voltage V1 and the voltage required for ink ejection is applied when the voltage is restored to the voltage V0 by the next charging, control of ink ejection and non-ejection should be performed. You can Therefore, with a simple circuit configuration, one electrode of each piezoelectric element can be grounded and grounded in common, and pull-out driving can be adopted as a driving method of the piezoelectric element. The piezoelectric element can be driven.

Next, a fifth embodiment of the ink jet head driving device according to the present invention will be described with reference to FIGS. FIG. 17 is a circuit block diagram showing the configuration of the inkjet head driving device of the fifth embodiment. FIG.
8 is a timing chart showing the operating state and voltage of each part of FIG.

In the fifth embodiment, the charging / discharging unit is, for example, k
.., and, for example, m data transistors Q41, Q42, ..

The charge / discharge circuit A1 is connected to the piezoelectric elements Z11, Z21, ... Via the resistor R7, and the charge / discharge circuit A2 is connected to the piezoelectric element Z12, via the resistor R7.
Z22, ..., Generates the striking signal waveforms, respectively, and outputs the output voltages S1, S2 composed of the striking signals as shown in FIG. 18 according to the timing signal input from the timing control unit 1. is there.

The data transistor Q41 has an emitter connected to the power supply 30, a base connected to the output terminal P1 of the print data output section 2, and a collector connected to the other of the piezoelectric elements Z11, Z12, ... Through the forward diode D5. Connected to the electrode. In addition, the data transistor Q
42 has the same configuration, the emitter is connected to the power supply 30, the base is connected to the output terminal P2 of the print data output unit 2, and the collector is the other of the piezoelectric elements Z21, Z22, ... Through the forward diode D5. Connected to the electrode.

The print data output section 2 outputs data transistors Q41, Q from the m output terminals P1, P2, ... According to the timing signal input from the timing control section 1.
42, ... are simultaneously output in parallel to the bases. Further, k print data is serially output from each output terminal in accordance with the timing signal input from the timing control section 1.

The timing control section 1 sequentially outputs timing signals from the k output terminals T1, T2, ... In synchronization with the timing signal output to the print data output section 2, and in synchronization with the serial output of print data. Charge / discharge circuit A1, A
2, a pull-out signal waveform is sequentially output to perform a dynamic scan.

With the above-mentioned structure, the data transistor Q4 is generated by the print data output from the print data output unit 2.
ON / OFF of 1, Q42, ... Is controlled.

Here, when ejecting ink drops from the nozzles, the data transistors Q41, Q42, ... Are turned off. As a result, when a discharge signal is output from each charging / discharging circuit, it is applied to the other electrode of each piezoelectric element via the resistor R7. Therefore, in the steady state, the voltage V0 is applied to each piezoelectric element, and once the pull-out signal is applied, the voltage drops to V1 and then suddenly rises to the voltage V0, and ink droplets are ejected from the nozzles of each piezoelectric element.

On the other hand, when ink droplets are not ejected from the nozzle, the data transistors Q41, Q42, ... Are turned on. As a result, the voltage V0 is applied from the power source 30 to the other electrode of each piezoelectric element via the diode D5, and the voltage applied between the electrodes of each piezoelectric element is maintained at the voltage V0. No ink droplet is ejected from the nozzle.

Next, the piezoelectric elements Z11, Z12, Z21,
The operation of Z22 will be described with reference to FIG. Initially, since the data transistors Q41 and Q42 are turned on, the voltage V0 is applied to each piezoelectric element. Then, the dynamic scan of the charge / discharge circuits A1, A2, ... Is started.

First, the timing signal from the timing control section 1 outputs a pull-out signal as the output voltage S1 of the charging / discharging circuit A1. The print data output section 2 outputs the pull-out signal in synchronization with the output timing of the pull-out signal. The data transistors Q41 and Q42 are turned off by the print data.

As a result, the output voltage S1 of the charge / discharge circuit A1 is applied to the piezoelectric elements Z11 and Z21, and the output voltage S2 of the charge / discharge circuit A2 is applied to the piezoelectric elements Z12 and Z22.

Therefore, the piezoelectric elements Z11 and Z21 are applied with the strike-off signals as the applied voltages V11 and V21,
Ink droplets are ejected from the nozzles of each piezoelectric element. on the other hand,
A voltage V0 is applied to the piezoelectric elements Z12 and Z22 as the output voltage S2 of the charging / discharging circuit A2.
The applied voltages V12 and V22 to 12, Z22 are maintained at the voltage V0, and ink droplets are not ejected from the nozzle of each piezoelectric element.

Next, the data transistors Q41, Q4
2 turns back on.

Next, the timing signal from the timing control unit 1 outputs a pull-out signal as the output voltage S2 of the charging / discharging circuit A2, and the print data output unit 2 synchronizes with the output timing of this pull-out signal. The print data of turns off the data transistor Q41 and maintains the data transistor Q42 in the on state.

As a result, the piezoelectric element Z11 receives the output voltage S1 of the charge / discharge circuit A1, the piezoelectric elements Z21 and Z22 receive the voltage V0 of the power supply 30, and the piezoelectric element Z12 receives the output voltage S2 of the charge / discharge circuit A2. Applied respectively.

Therefore, the pull-out signal is applied only to the piezoelectric element Z12, the voltage V0 is continuously applied to the piezoelectric elements Z11, Z21, Z22, and the ink droplets are ejected from the nozzles of the piezoelectric element Z12. Z11, Z21, Z
No ink droplets are ejected from the 22 nozzles.

The same operation is performed thereafter. Then, in the next cycle, a timing signal from the timing control unit 1 outputs a pull-out signal as the output voltage S1 of the charging / discharging circuit A1, and the print data output unit 2 synchronizes with the output timing of the pull-out signal. Only the data transistor Q42 is turned off by the print data from.

Accordingly, the voltage V0 of the power source 30 is applied to the piezoelectric elements Z11 and Z12, the output voltage S1 of the charge / discharge circuit A1 is applied to the piezoelectric element Z21, and the output voltage S2 of the charge / discharge circuit A2 is applied to the piezoelectric element Z22. Applied respectively.

Therefore, the pull-out signal is applied only to the piezoelectric element Z21, the voltage V0 is continuously applied to the piezoelectric elements Z11, Z12, Z22, and the ink droplets are ejected from the nozzles of the piezoelectric element Z21. Z11, Z12, Z
No ink droplets are ejected from the 22 nozzles.

Further, according to the timing signal from the next timing control unit 1, the pull-out signal is output as the output voltage S2 of the charging / discharging circuit A2, but since there is no print data, it is synchronized with the output timing of the pull-out signal. The data transistors Q41 and Q42 do not turn off but remain on.

As a result, the piezoelectric elements Z11, Z12,
The voltage V0 of the power supply 30 is applied to Z21 and Z22.
Therefore, the voltage V0 is continuously applied to the piezoelectric elements Z11, Z12, Z21, Z22, and ink droplets are not ejected from each nozzle.

As described above, in the fifth embodiment, the output voltages VS1, S2, ... From the charging / discharging circuits A1, A2 ,. Since the voltage V0 is continuously applied by the data transistors Q41, Q42, ..., Ink ejection or non-ejection can be controlled. Therefore, with a simple circuit configuration, one electrode of each piezoelectric element can be grounded and grounded in common, and pull-out driving can be adopted as a driving method of the piezoelectric element, and m × k piezoelectric elements can be driven by time-division matrix driving. Can be driven.

Next, an example in which the circuit configuration of the fifth embodiment is slightly modified will be described with reference to FIGS. 19 and 20. FIG.
9 is a circuit block diagram showing a configuration of a modified example of the fifth embodiment, and FIG. 20 is a timing chart showing operation states and voltages of respective parts of FIG.

In the circuit of FIG. 19, the charge / discharge circuit A of FIG.
1, A2, ... Instead of k analog switches W1, W
2, ... and each analog switch W1,
A common charge / discharge circuit A0 is connected to W2, ....

The charging / discharging circuit A0 generates the striking signal waveform and, in accordance with the timing signal input from the timing control section 1, outputs the output voltage S0 composed of the striking signal as shown in FIG. It is output repeatedly. Analog switches W1, W2, ...
Are sequentially turned on according to the timing signals input from the output terminals T1, T2, ... Of the timing control unit 1.

The timing control section 1 sequentially outputs timing signals from the output terminals T1, T2, ... In synchronization with the timing signals output to the charging / discharging circuit A0 and the print data output section 2 to serially output and charge the print data. Discharge circuit A0
Analog switch W1, in synchronization with the pull-out signal from
W2, ... Are sequentially turned on to perform a dynamic scan.

With the above configuration, as shown in FIG.
Output voltage S1, S of the analog switches W1, W2, ...
, ... can obtain voltage outputs similar to the output voltages S1, S2, ... Of the charging / discharging circuits A1, A2 ,.
Therefore, since the same operation as in the case of FIG. 17 is performed, the same effect can be obtained.

In each of the above embodiments, the voltage applied to the electrode of each piezoelectric element by each power source on the side not grounded is described as a positive voltage, but the polarity is reversed and a negative voltage is applied. Even if it does, the same effect can be obtained.

[0199]

As described above, according to the invention of claim 1, the respective piezoelectric elements of the piezoelectric element section are wired in a matrix of m rows and k columns, time division is performed k times, and each time, Since the pulling-out signal is applied between the electrodes of the piezoelectric elements having print data in the m pieces in each column, high ink-jetting performance can be obtained by the pulling-out driving.

According to the second aspect of the present invention, each piezoelectric element of the piezoelectric element portion is wired in a matrix of m rows and k columns, and one electrode is grounded and time-divided into k times. In addition, since the pulling-out signal is applied between the electrodes of the piezoelectric elements having print data in the m pieces in each column, the piezoelectric element portion can be simply configured and high ink can be driven by the pulling-out driving. Discharge performance can be obtained.

According to the invention of claim 3, the voltage applied between the electrodes of the other (k-1) piezoelectric elements of the piezoelectric elements of each row is closer to the first level than the second level. When the level changes and returns to the first level, ink is ejected from the nozzles by pressurization of the pressure chamber by the piezoelectric element when a signal that returns from the third level to the first level is applied between the electrodes of the piezoelectric element. Since the third level is set to a value that does not eject ink, it is possible to reliably control the ejection or non-ejection of ink from the nozzles of each piezoelectric element in time-division matrix driving.

According to the fourth aspect of the invention, the first level voltage application between the electrodes of the m piezoelectric elements in each column is sequentially turned off by the k charging sections for a predetermined time over k times. Each time, the voltage applied between the electrodes of the piezoelectric elements with print data among the m electrodes in each row is discharged for a predetermined time in synchronization with this turning off by the m number of discharge parts, and reaches the second level. By changing the voltage, the applied voltage returns to the first level by turning on the charging unit after a predetermined time after each time, so that the striking signal is applied between the electrodes of the piezoelectric element with print data. The piezoelectric element portion can be simply configured, and high ink ejection performance can be obtained by pulling and driving.

According to the fifth aspect of the invention, the voltage division level obtained by dividing the ratio of the resistance values of the first resistance and the second resistance by the voltage of the first level by the first resistance and the second resistance is the third. Since the level is set, it is possible to reliably control ink ejection and non-ejection from the nozzles of each piezoelectric element in time-division matrix driving.

According to the sixth aspect of the present invention, the charging section is configured such that the voltage source of the first level is connected to the other electrode of the piezoelectric element via the first switch element and the current limiting resistor, respectively. The discharge part is configured such that the other electrode of the piezoelectric element is grounded through the current limiting resistor and the series circuit including the second switch element and the resistor, and the third level is equal to the first level. Therefore, in time-division matrix driving, it is possible to more reliably control the ejection and non-ejection of ink from the nozzles of each piezoelectric element.

According to the invention of claim 7, the voltage applied between the electrodes of the piezoelectric element having print data is changed to the second level by both the first and second discharge parts, and the charge is applied after the off time. The applied voltage is returned to the first level by the charging section, and the fourth and fifth charging sections after the off time from the change to the fourth level by the first discharging section and the change to the fifth level by the second discharging section. Since the fourth and fifth levels are set so that ink is not ejected from the nozzle due to pressurization of the pressure chamber by the piezoelectric element when the return signal from the level to the first level is applied, the piezoelectric element with print data It is possible to reliably apply ink ejection and non-ejection from the nozzles of each piezoelectric element in time-division matrix driving, while applying a pull-out signal between the electrodes.

According to the invention of claim 8, the resistance value of the first resistor is set so that the applied voltage is changed from the first level to the fourth level by the discharge operation of the first discharge section during the off time. Since the resistance value of the second resistor is set so that the applied voltage changes from the first level to the fifth level by the discharge operation during the off time of the second discharge section, the ink from the nozzles of each piezoelectric element is driven in time-division matrix driving. It is possible to reliably control ejection and non-ejection.

According to the invention of claim 9, the voltage applied between the electrodes of the other (k-1) piezoelectric elements of the piezoelectric elements in each row is changed to the second level, and the voltage is changed from the second level to the first level. A pressurizing chamber by a piezoelectric element when a signal for changing the predetermined rate of change from a second level to a first level is applied between the electrodes of the piezoelectric element, the pressure chamber changing to a first level at a predetermined rate of change. Since the value is set so that the ink is not ejected from the nozzle by the pressurization, it is possible to reliably control the ink ejection or non-ejection from the nozzle of each piezoelectric element in the time-division matrix driving.

According to the tenth aspect of the invention, every time the first charging section is turned off for the first off time, the voltage is applied between the electrodes of the piezoelectric element having print data out of m pieces in each column. The voltage is changed from the first level to the second level by the discharging operation of the discharging unit for the first off time, and the applied voltage is returned to the first level by turning on the first charging unit after the first off time, and the strike signal is generated. And the voltage applied between the electrodes of the other (k-1) piezoelectric elements in each row is changed from the second level to the nozzle by the voltage applied by the second charging unit when the discharging operation of the discharging unit is stopped. Since the ink is not ejected from the device, the ink is ejected from the nozzles of each piezoelectric element in the time-division matrix drive while applying a striking signal between the electrodes of the piezoelectric element with print data. Non-ejection control It can be carried out reliably.

According to the eleventh aspect of the invention, each time the second charging section is turned off, the discharge operation of the discharging section during the off time causes the electrode of the piezoelectric element having print data to be included in the m pieces of m in each column. The applied voltage between the first level and the second level is changed, and the applied voltage is returned to the first level by the operation of the first charging unit to form the strike signal, and the other
The voltage applied between the electrodes of the (k-1) piezoelectric elements is changed from the second level to the first level at a predetermined change rate by the second charging section when the discharging operation of the discharging section is stopped. It is possible to apply a pull-out signal between the electrodes of the piezoelectric element having print data, and to reliably control the ejection and non-ejection of ink from the nozzle of each piezoelectric element in time-division matrix driving.

According to the twelfth aspect of the present invention, the pulling-out signal is applied between the electrodes of the m piezoelectric elements in each column in order by the k-pulling-out signal applying portions k times, and each time, the pulling-out signal is applied. In addition, since the voltage applied between the electrodes of the piezoelectric elements having no printing data among the m pieces is held at the first level, ink ejection and non-ejection from the nozzles of each piezoelectric element in the time-division matrix drive. It is possible to reliably control and apply the pull-out signal only between the electrodes of the piezoelectric element having print data.

According to the thirteenth aspect of the invention, the k switching elements are sequentially turned on k times, and the pulling signal is generated between the electrodes of the m piezoelectric elements in each column from the pulling signal generation section. Is applied, and the applied voltage between the electrodes of the piezoelectric elements having no print data is kept at the first level in m of each time, so that in the time-division matrix drive, the voltage from the nozzle of each piezoelectric element is Ink ejection and non-ejection can be reliably controlled, and the pull-out signal can be reliably applied only between the electrodes of the piezoelectric element having print data.

According to the fourteenth aspect of the invention, the drive voltage signal is applied to the predetermined number of piezoelectric elements at timings sequentially shifted by at least the pulse width of the pulse current flowing when the drive voltage signal is applied. Therefore, when driving a predetermined number of piezoelectric elements, pulse current does not flow at the same time,
The superposition of pulse currents can be reduced, which can prevent voltage fluctuations and reduce the size of the driving means.

According to the fifteenth aspect of the invention, the drive voltage signal is applied to the plurality of piezoelectric elements at timings sequentially shifted by at least the pulse width of the pulse current flowing when the drive voltage signal is applied. Therefore, when the piezoelectric element is driven, the pulse current does not flow at the same time, and the pulse current can be prevented from being superposed, whereby the voltage fluctuation can be prevented and the driving means can be downsized.

According to the sixteenth aspect of the invention, the piezoelectric element portion is provided with a group having a predetermined number of piezoelectric elements as a unit, so that only the same number of piezoelectric elements as the group are simultaneously driven and the pulse current is generated. Since the pulse currents do not flow at the same time when driving a predetermined number of piezoelectric elements forming each group, it is possible to reduce the overlapping of the pulse currents, thereby preventing voltage fluctuations and preventing The size can be reduced.

According to the seventeenth aspect of the invention, the drive voltage signals are applied to the piezoelectric elements in each group at timings sequentially shifted by at least their pulse widths, and the piezoelectric elements in each group are applied. Since the drive voltage signal is applied to each corresponding subgroup at a timing shifted by at least the pulse width of the pulse current flowing into the piezoelectric element when the drive voltage signal is applied, only the piezoelectric elements forming the subgroup are simultaneously Since the pulse current is driven and superposed, the pulse current does not flow to the other piezoelectric elements at the same time. Therefore, the superposition of the pulse current can be reduced, which prevents voltage fluctuations and reduces the size of the driving means. Can be realized.

According to the eighteenth aspect of the present invention, the piezoelectric elements arranged in a matrix forming a group are:
A drive voltage signal is applied to each column at a timing sequentially shifted by at least the pulse width, and the drive voltage signal for each corresponding column flows into the piezoelectric element at least when the drive voltage signal is applied. Since the pulse current is applied at a timing shifted by the pulse width of the pulse current, only the piezoelectric elements that make up the column are driven at the same time and the pulse current is superimposed, and the pulse current does not flow to other piezoelectric elements at the same time. Further, it is possible to reduce the superposition of pulse currents, thereby preventing voltage fluctuations and reducing the size of the driving means.

[Brief description of drawings]

FIG. 1 is a perspective view showing an ink ejection portion of a recording head of an inkjet head driving device according to the present invention.

FIG. 2 is a block diagram showing a configuration of a first embodiment of an inkjet head driving device according to the present invention.

FIG. 3 is a timing chart showing voltage, current, and print data output from a print data output unit at each point.

FIG. 4 is a block diagram showing a configuration of a second embodiment of an inkjet head driving device according to the present invention.

FIG. 5 is a timing chart showing voltage signals at respective points and print data of a print data output unit.

FIG. 6 is a timing chart showing an output voltage signal of each charge / discharge circuit and a pulse current flowing through each piezoelectric element.

FIG. 7 is a circuit block diagram showing a configuration of a third embodiment of an inkjet head driving device according to the present invention.

FIG. 8 is a timing chart showing operating states and voltages of the respective parts of FIG.

FIG. 9 is a circuit block diagram showing a configuration of a first modified example of the third exemplary embodiment.

FIG. 10 is a timing chart showing operating states and voltages of the respective parts in FIG.

FIG. 11 is a circuit block diagram showing a configuration of a second modification of the third embodiment.

FIG. 12 is a timing chart showing operating states and voltages of respective parts in FIG.

FIG. 13 is a circuit block diagram showing a configuration of a third modification of the third embodiment.

FIG. 14 is a timing chart showing operating states and voltages of the respective parts in FIG.

FIG. 15 is a circuit block diagram showing a configuration of a fourth embodiment of an inkjet head driving device according to the present invention.

16 is a timing chart showing the operating state and voltage of each part of FIG.

FIG. 17 is a circuit block diagram showing a configuration of a fifth embodiment of an inkjet head driving device according to the present invention.

FIG. 18 is a timing chart showing operating states and voltages of the respective parts in FIG.

FIG. 19 is a circuit block diagram showing a configuration of a modified form of the fifth embodiment.

FIG. 20 is a timing chart showing operating states and voltages of the respective parts in FIG.

[Explanation of symbols]

1, 101 Timing control unit 2 Print data output unit 30, 40 Power supply A0, A1, A2 Charge / discharge circuit D1 to D4 Diodes Q0, Q30 Common transistor Q11 to Q1k, Q31 to Q3k Segment transistor Q21 to Q2m, Q41, Q42 Data transistor R1 to R7 resistors Z11 to Z1k, Z21 to Z2k, Zm1 to Zmk piezoelectric element

Claims (18)

[Claims] 1. In an ink jet recording apparatus that ejects ink onto a recording medium in accordance with print data from a plurality of nozzles arranged in a recording head, one side wall of a pressure chamber communicating with each of the nozzles is formed. A piezoelectric element part provided with a piezoelectric element having a pair of electrodes wired in a matrix of m rows and k columns, and time-divided into k times, each time pressurization by the piezoelectric element in the pressurizing chamber After temporarily changing the applied voltage between the electrodes of the piezoelectric element from the first level to the second level closer to the ground potential, the pressurizing chamber is pressurized again to eject ink from the nozzles. Therefore, a pull-out signal for returning the applied voltage to the first level is applied between the electrodes of the piezoelectric element having the print data within the m number of m in each column, and the other (k
-1) An ink jet head drive device comprising a time division matrix drive circuit for applying a voltage signal such that ink is not ejected from the nozzles, between the electrodes of the one piezoelectric element. 2. The ink jet head driving device according to claim 1, wherein one of the pair of electrodes of each piezoelectric element is grounded. 3. The time-division matrix drive circuit applies the voltage applied between the electrodes of the piezoelectric element having the print data, out of m in each row, from the first level to the second level at each time. When returning to the first level by changing to, the voltage applied between the electrodes of the other (k-1) piezoelectric elements of the piezoelectric elements in each row is closer to the first level than the second level. The level is changed to three levels to return to the first level, and the third level is when a signal for returning from the third level to the first level is applied between the electrodes of the piezoelectric element. 3. The ink jet head drive device according to claim 2, wherein a value is set so that ink is not ejected from the nozzle due to pressurization of the pressure chamber by the piezoelectric element. 4. The time-division matrix driving circuit comprises k charging units for applying the first level voltage between m electrodes of the piezoelectric elements in each column, and k charging units in each row.
M discharge units that change the applied voltage between the electrodes of the piezoelectric elements to the second level by discharging, and a timing control unit that sequentially turns off the voltage application by the k charging units for a predetermined period of time. And a print data output unit that causes the discharge operation by the m discharge units to be performed for the predetermined time when the print data is present. Each time the charging unit is turned off, By the discharging operation, the voltage applied to the electrode of the piezoelectric element having the print data is changed from the first level to the second level in the m pieces in each column, and the charging unit is turned on after the predetermined time. 4. The inkjet head driving device according to claim 3, wherein the applied voltage is returned to the first level to form the pull-out signal. 5. The charging section is configured such that the first level voltage power supply is connected to the other electrode of the piezoelectric element via a series circuit including a first switch element and a first resistor, respectively, and the discharging section is provided. Is configured such that the other electrode of the piezoelectric element is grounded via a series circuit including a second switch element and a second resistor, respectively, and the timing control unit controls ON / OFF of the first switch element. The print data output unit controls ON / OFF of the second switch element, and includes the first resistor and the second resistor.
The ratio of the resistance values of the resistors is determined by comparing the first level voltage with the first level voltage.
5. The inkjet head drive device according to claim 4, wherein the voltage division level divided by the resistance and the second resistance is set to be the third level. 6. The charging section is configured such that the first-level voltage power supply is connected to the other electrode of the piezoelectric element via a first switch element and a current limiting resistor, respectively, and the discharging section is The other electrode of the piezoelectric element is grounded via the current limiting resistor and the series circuit including the second switch element and the resistor, respectively, and the timing control unit controls ON / OFF of the first switch element. The print data output unit controls ON / OFF of the second switch element, and the third level is equal to the first level. 4. The inkjet head drive device according to item 4. 7. The time-division matrix drive circuit comprises: a charging unit for applying the voltage of the first level between electrodes of the piezoelectric element; and a voltage applied between electrodes of m piezoelectric elements in each column. Discharge from the first level to a fourth level close to the ground potential by discharging, and the voltage applied between the electrodes of the k piezoelectric elements in each row to the first level by discharging. From the 5th close to the ground potential
M second discharging units for changing the level, a first timing control unit for turning on and off the charging unit at a predetermined cycle,
A second timing control unit for sequentially performing the discharging operation by the k first discharging units for each off time of the charging unit, and the discharging operation by the m second discharging units for the charging when the print data is present. A print data output section for performing only the off time of the piezoelectric element, and when both the first and second discharge sections perform the discharge operation for the off time, the voltage applied to the electrode of the piezoelectric element is at the first level. To the second level, the charging unit is turned off and the first discharging unit performs a discharging operation each time the second discharging unit performs the discharging operation during the off time. The applied voltage to the electrode of the piezoelectric element having the print data is changed from the first level to the second level among the m pieces in each column, and the applied voltage is generated by turning on the charging unit after the off time. Return to the first level above Allowed to as to form the pull beating signal, the fourth level, the first from the fourth level
When the signal for returning to the level is applied between the electrodes of the piezoelectric element, the piezoelectric element pressurizes the pressure chamber so that ink is not ejected from the nozzle. It is set to a value such that ink is not ejected from the nozzle due to pressurization of the pressure chamber by the piezoelectric element when a signal for returning from the 5th level to the first level is applied between the electrodes of the piezoelectric element. The inkjet head driving device according to claim 2, wherein 8. The first discharge part is configured such that the other electrode of the piezoelectric element is grounded via a series circuit including a first switch element and a first resistor, and the applied voltage is changed to the first voltage by the discharge. The level is changed from 1 level to a level determined by the resistance value of the first resistor, and the second discharge portion is configured such that the other electrode of the piezoelectric element is connected via a series circuit including a second switch element and a second resistor. It is grounded and changes the applied voltage from the first level to a level determined by the resistance value of the second resistor by discharge. The second timing control section turns on and off the first switch element. The print data output section controls ON / OFF of the second switch element, and the resistance value of the first resistor is the discharge value during the OFF time of the first discharge section. By the operation, the applied voltage is the first voltage
It is set to change from the level to the 4th level,
The resistance value of the second resistor is set such that the applied voltage changes from the first level to the fifth level by the discharge operation of the second discharge unit during the off time. Item 7. The inkjet head drive device according to item 7. 9. The time-division matrix drive circuit, every time, the applied voltage between the electrodes of the piezoelectric element having the print data among the m pieces in each column is changed from the first level to the second level. To return to the first level by changing the voltage applied between the electrodes of the other (k-1) piezoelectric elements of each row of the piezoelectric elements to the second level. The level is changed from the level to the first level at a predetermined rate of change, and at the predetermined rate of change, a signal changing from the second level to the first level is applied between the electrodes of the piezoelectric element. The ink jet head drive device according to claim 2, wherein a value is set so that ink is not ejected from the nozzle due to pressurization of the pressure chamber by the piezoelectric element at this time. 10. The time-division matrix driving circuit includes k first charging units for applying the first level voltage between m electrodes of the piezoelectric elements in each column, and k charging units in each row. Of m discharge units that change the voltage applied between the electrodes of the piezoelectric element to the second level by discharging, and a second charging unit that applies a voltage between the electrodes of each piezoelectric element at the predetermined change rate. A timing control unit that turns on and off the voltage application by each of the first charging units at a predetermined cycle and sequentially reduces the off time of the k first charging units to the first off time; and the m discharging units. A print data output unit that causes the discharge operation by the unit to be performed for the first off time when the print data is present, and each time the first charging unit is turned off for the first off time, Piezoelectric element with the above print data out of m The voltage applied between the electrodes of the child is changed from the first level to the second level by the discharging operation of the discharging unit for the first off time, and the first charging unit is turned on after the first off time. The applied voltage is returned to the first level to form the knock-out signal,
The voltage applied between the electrodes of the other (k-1) piezoelectric elements in each row is determined from the second level by the voltage applied by the second charging section when the discharging operation of the discharging section is stopped. 10. The ink jet head drive device according to claim 9, wherein the ink jet head drive device is configured to change at a rate of change. 11. The time-division matrix driving circuit includes k first charging units that apply the first level voltage between m electrodes of the piezoelectric elements in each column, and k first charging units in each row. Of m discharge units that change the voltage applied between the electrodes of the piezoelectric element to the second level by discharging, and a second charging unit that applies a voltage between the electrodes of each piezoelectric element at the predetermined change rate. And turning on the second charging unit at a predetermined cycle,
The first timing control unit for turning off and the discharge operation by the m number of discharge units are used for the second operation when the print data is present.
A second timing control unit for sequentially operating the k first charging units in synchronism with the turning on of the second charging unit; Every time the charging section is turned off, the voltage applied between the electrodes of the piezoelectric element having the print data among the m pieces in each row is changed from the first level to the above by the discharging operation of the discharging section during the off time. The second level is changed, and the applied voltage is returned to the first level by the operation of the first charging unit to form the pull-back signal.
-1) The voltage applied between the electrodes of the one piezoelectric element changes from the second level to the first level at the predetermined rate of change by the second charging unit when the discharging operation of the discharging unit is stopped. 10. The method according to claim 9, wherein
The inkjet head driving device described. 12. The time-division matrix driving circuit comprises k pull-out signal application units for applying the pull-out signal between electrodes of m piezoelectric elements in each column, and k pull-out signal application units in each row. M voltage holding units that hold the voltage applied between the electrodes of the piezoelectric element at the first level, and a timing control unit that sequentially applies the pulling-out signals by the k pulling-out signal applying units. , A print data output section for performing the holding operation by the m voltage holding sections for the application time of the pull-out signal when there is no print data, and each time the pull-out signal is applied, M in row
3. The ink jet head according to claim 2, wherein the voltage applied between the electrodes of the piezoelectric element without the printing data is held at the first level by the voltage holding unit. Drive. 13. The pulling-out signal applying section for k number of times, the pulling-out signal generating section for repeatedly generating the pulling-out signal, the other electrode of the m piezoelectric elements in each column, and the pulling-out type. It is composed of k switch elements connected between the signal generation sections, and the timing control section turns on the k switch elements in sequence in synchronization with the generation of the pull-out signal. The inkjet head drive device according to claim 12. 14. In an ink jet recording apparatus for ejecting ink onto a recording medium corresponding to print data from a plurality of nozzles arranged in an array on a recording head, one side wall of the plurality of pressurizing chambers communicating with each of the nozzles is formed. Piezoelectric element portions each provided to form a piezoelectric element that deforms when a drive voltage signal is applied and ejects ink from the nozzle, and the plurality of piezoelectric element portions that apply the drive voltage signal to the corresponding piezoelectric elements. And the driving voltage signal is sequentially shifted by at least the pulse width of the pulse current flowing into the piezoelectric element when the driving voltage signal is applied to at least a predetermined number of the piezoelectric elements among the plurality of piezoelectric elements. An ink jet head driving device, comprising: a timing control unit that applies the voltage at different timings. 15. The ink jet head driving device according to claim 14, wherein the predetermined number is equal to the plurality. 16. The ink jet head drive device according to claim 14, wherein the piezoelectric element section includes a plurality of groups each including the predetermined number of piezoelectric elements as a unit. 17. An ink jet recording apparatus for ejecting ink onto a recording medium corresponding to print data from a plurality of nozzles arrayed in a recording head, wherein one side wall of the plurality of pressurizing chambers communicating with the nozzle is provided. Piezoelectric elements that are respectively provided to be formed and that deform when a drive voltage signal having a predetermined pulse width is applied to eject ink from the nozzles are divided into a plurality of groups each including a predetermined number of the piezoelectric elements. At the same time, at least the above-mentioned piezoelectric elements of each divided group are divided into a plurality of sub-groups each consisting of a predetermined number of piezoelectric elements, and the piezoelectric elements in the divided groups are at least for each of the sub-groups. Drive means of the number of divided groups for applying the drive voltage signal at timings sequentially shifted by the pulse width of the drive voltage signal And a timing at which the drive voltage signal is applied to the piezoelectric elements of the corresponding sub-group of each divided group at timings sequentially shifted by at least the pulse width of the pulse current flowing into the piezoelectric element when the drive voltage signal is applied. An inkjet head driving device comprising: a control unit. 18. The predetermined number of piezoelectric elements forming the group are arranged in a matrix of a plurality of rows and columns, and the predetermined number of piezoelectric elements forming the sub-group are arranged in the columns. 18. The ink jet head drive device according to claim 17, wherein the ink jet head drive device is a piezoelectric element constituting the device.