JPH0664166A - Driving method for ink jet head - Google Patents

Abstract

PURPOSE:To achieve simplification of a driving circuit for a piezoelectric ink jet head without lowering the limits of printing speed. CONSTITUTION:Electrodes on one end of each of piezoelectric elements that drive a plurality of nozzles in a piezoelectric ink jet head are made independent driving electrodes 121, 122, 123 and 124 while electrodes on the other end are connected with one another and are made a common electrode 141, and is grounded. The driving electrodes are then connected to the line of positive electric source through charging pnp bipolar transistors 41, 42, 43 and 44 while being grounded through isolating diodes 51, 52, 53 and 54 and a common discharging npn bipolar transistor 48. Charging is made selectively by the aforementioned charging pnp bipolar transistors to the capacity of the piezoelectric elements, and discharging is made by the common discharging npn bipolar transistor.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printer, and more particularly to a piezoelectric ink jet head using a shear mode and a driving method thereof.

[0002]

2. Description of the Related Art A deformation of a piezoelectric element in a shear mode is used to deform a partition wall of a channel-shaped pressure chamber filled with ink, and a pressure rise in the pressure chamber thereby causes the ink to project. A technique relating to a driving method is described in, for example, Japanese Patent Laid-Open No. 18054/1990.

Further, an electrostrictive element is attached to the upper plate of the ink chamber, and the upper surface of the upper ink chamber is deformed by bending deformation due to the expansion and contraction of the electrostrictive element, whereby the ink is projected and the ink is projected. A technique relating to a drive system is described in, for example, Japanese Patent Laid-Open No. 61-263760.

[0004]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
A conventional drive circuit for a print head of a type in which a partition of a pressure chamber is deformed by utilizing a shear mode of a piezoelectric element as described in Japanese Patent Publication No. JP-A-2004-242242 is used to generate ink as shown in FIG. 2 or FIG. A driver corresponding to each of the drive electrodes of the plurality of grooves forming the pressure chamber to be ejected is required. In order to repeatedly charge and discharge the drive electrode, such a driver includes a first switch means interposed between the drive electrode and the high potential side of the power source, and a second switch means interposed between the drive electrode and the high potential side of the power source. Since the switching means is required, the circuit as a whole becomes complicated, and the head itself has an advantage that it is suitable for miniaturization of printing dots and cost reduction as compared with other methods, while increasing the cost of the drive circuit and It has the disadvantage of increasing the space.

In order to eliminate this defect, a head having a structure as described in JP-A-63-247051 is driven by a time-division drive system as described in JP-A-63-247051. The structure itself of the drive circuit can be simplified. However, in order to increase the printing speed of the inkjet head, when the printing frequency is brought close to the response frequency of the nozzle, it becomes difficult to shift the driving timing for each time-division group and drive with a common driver. In other words, if the number of time divisions is increased in order to simplify the drive circuit, there arises a problem that the allowable printing speed is reduced in order to avoid duplication of drive timing for each group. Such a problem is caused not only by an ink jet head utilizing the shear mode but also by JP-A-61-61.
This problem is common to all piezoelectric ink jet heads, including the ink jet head utilizing the bending mode disclosed in Japanese Patent Laid-Open No. 263760. An object of the present invention is to simplify a drive circuit in a piezoelectric inkjet head without lowering an allowable printing speed. Furthermore, it is an object of the present invention to simplify the drive circuit in the case of performing the time-divisional driving, compared to the conventional case, with the same number of time-divisions.

[0006]

In order to solve the above problems, an ink jet head driving method of the present invention has a plurality of nozzles, and the ink jets the ink in the nozzles by deforming the nozzles by piezoelectric driving. In the head, one electrode of the piezoelectric element that drives each of the plurality of nozzles is an independent drive electrode, the other electrode is connected between the nozzles to be a common electrode, and one electrode of the drive power supply is independent of the drive electrode. A switch means for charging is provided individually corresponding to each drive electrode, a common electrode is connected to the other terminal of the power supply, and an independent drive electrode is provided with a diode for separation and a common switch means for discharge. Is connected to the other terminal of the power source through the charging switch means to selectively charge the capacitance of the piezoelectric element, and the discharging is performed by the common discharging switch means. And wherein the Ukoto.

According to the method of driving an ink jet head of the present invention, in an ink jet head having a plurality of nozzles, and the nozzles are deformed by piezoelectric drive to eject ink in the nozzles, the plurality of nozzles are divided into time-division groups. , One electrode of the piezoelectric element that drives each of the plurality of nozzles is an independent drive electrode, the other electrode is connected to each group as a common electrode, and is connected between one terminal of the drive power source and an independent drive electrode. A switch means for charging is provided corresponding to the order of arrangement of the drive electrodes in each group, and a group driver is provided between the other terminal of the power source and the common electrode of each group to provide independent drive electrodes. Is connected to the other terminal of the power supply through a diode for separation and a switch means for common discharge, and is time-divided by a group driver. The switching means for charging each-option groups of nozzles, charges the capacitance of selectively the piezoelectric element, and performing by the discharge common discharge switch means.

[0008]

[Action]

(1) According to the ink jet head driving method of the present invention, a plurality of nozzles for printing simultaneously are driven by a driver having the same number of charging switch means and one common discharging switch means. Thus, charging and discharging between the common electrodes and the same number of drive electrodes as the nozzles are repeated. (2) Since each drive electrode is connected to the discharge switch means through the corresponding rectifying means such as a diode, each drive electrode can be independently driven without conduction. (3) According to the method for driving an inkjet head of the present invention, n having common electrodes and m nozzles are provided for each.
By connecting m × n nozzles of each group to the group selection switch means provided for each group in n time division, m charging switch means, m
It is possible to perform n time division driving by a common driver composed of a single rectifying means and a single discharging switch.

(4) Conventionally, the same number of charging switch means and discharging switch means were required for a plurality of nozzles that print simultaneously, but according to the present invention, the same number of discharging switches as nozzles are required. Instead of the means, one discharge switch means and as many rectifying means as diodes and the like as the nozzles may be used. Here, the rectifying means such as the diode has a simpler structure and lower cost than the switch means such as the bipolar transistor. Therefore, as the number of nozzles to be printed at the same time increases, the present invention is simplified in the drive circuit as compared with the conventional one. Will be excellent at. Moreover, since the time-division drive is not used, the printing speed does not decrease. (5) Of course, as described above, the present invention can be used for time-division driving. In this case as well, for the same reason as above, the driving circuit is superior to the conventional time division driving method in terms of simplification.

[0010]

【Example】

(Embodiment 1) (1) A first embodiment of the present invention will be described below with reference to the drawings. This embodiment is one embodiment of the present invention in a print head of a type in which the partition of the pressure chamber is deformed by utilizing the deformation of the piezoelectric element in the shear mode. Regarding the structure of the head 105 shown in FIGS. Substrate 101 made of piezoelectric material
A plurality of grooves, each including an ejection groove 111 that ejects ink from the ejection hole 110 and a dummy groove 112 that does not eject ink, and a drive partition 115 that drives the ink are formed on the upper surface of the drive partition 110 via an elastic member 103. It is connected to the lid 104. The drive partition 115 is polarized in the direction of the arrow in FIG. 2, and drive electrodes 121, 122, 123, 124 and a dummy electrode 128 are provided on the inner surfaces of the ejection groove 111 and the dummy groove 112, respectively.

By connecting to one end of the plurality of grooves, FIG.
A common groove 181 for supplying ink is formed as shown in FIG. 3, and communicates with the joint 182 to supply ink to the plurality of grooves from the outside. The plurality of grooves 111, 112
The other end is opened at one end face of the substrate 1, and the nozzle plate 108 is attached so as to close this opening. Figure 2
As shown in FIG. 5 and FIG. 5, the grooves are arranged such that the injection grooves 111 and the dummy grooves 112 are alternately arranged and the dummy grooves are arranged at both ends. The dummy groove electrodes 128 are connected to each other to form a common electrode 141. The nozzle plate 108 is provided with injection holes 110 corresponding to the injection grooves 111. Since the drive electrode faces the common electrode across the drive partition made of a piezoelectric material and forms a capacitor there, when the drive terminal is attached to the drive electrode, the equivalent circuit of the head is a series circuit of capacitors as shown in FIG. However, this is equivalent to the parallel circuit of the capacitors shown in FIG. 7, and charging / discharging can be performed independently for each drive electrode.

(2) Next, a method of driving the above print head will be described with reference to the equivalent circuit of FIG. As shown in FIG. 1, the common electrode 141 is grounded. The positive power supply line of the drive circuit has a pnp bipolar transistor 41, 4 for charging.
The emitters of 2, 43, and 44 are connected, and the drive electrodes 121, 122, 123, and 124 are connected to the collectors of the pnp bipolar transistors 41, 42, 43, and 44, respectively, and a common npn bipolar transistor for discharging is used. Isolation diodes 51, 52, 53, and 54 connected in the forward direction are connected to the collector of 48, respectively. The emitter of the discharging npn bipolar transistor 48 is grounded.

(3) Now, as shown in the timing chart of FIG. 9, with the period T and the pulse width τ, the r-th (r is 1, 2,
It is an arbitrary number of 3 and 4. ) The channel selection signal Qpr and the control signal Qnn which rise at the pulse width τ are simultaneously added to the bases of the pnp bipolar transistors 41, 42, 43 and 44 for charging and the base of the npn bipolar transistor 48 for discharging, and the signals rise. The pnp bipolar transistor is made conductive and the npn bipolar transistor is made nonconductive during the period of τ during the period of τ, and the pnp bipolar transistor is made nonconductive and the npn bipolar transistor is made conductive during the other period. While the channel selection signal is rising, the r-th drive electrode is electrically connected to the positive power supply line of the power supply, while the common electrodes 141, which are arranged on both sides of the electrode and are opposite electrodes of the capacitor, are grounded. Therefore, a current flows into the capacitor for charging, and the potential P of the drive electrode 121 becomes higher than the potential of the common electrode 141. As a result,
An electric field is applied from the inner side to the outer side of the capacitors formed by the two drive partition walls 115 that form the wall surfaces on both sides of the injection groove, and a shear force toward the outside is generated on the partition walls on both sides of the drive partition wall 1.
As shown in FIG. 3, 15 is deformed to the outside and sucks ink into the groove.

Next, after the period τ has passed, the drive electrode is electrically connected to the ground via the isolation diode and the discharging npn bipolar transistor 48, and the common electrode 1
Since 41 is originally grounded, a discharge loop is formed between the drive electrode and the common electrode, discharge is performed, the voltage P of the drive electrode becomes the ground level, the electric field in the drive partition 115 disappears, and the drive partition Quickly returns to its original state. At this time, the ink in the groove is compressed and droplets are ejected from the ejection holes 110. Although the case of driving the r-th drive electrode has been described above, one or more arbitrary drive electrodes are selectively driven based on the data signal applied to the base of the pnp bipolar transistor for charging. A print pattern can be formed. At this time, the inflow of current from the selected drive electrode to the non-selected drive electrode is blocked by the diode, and the drive independence is maintained.

(4) As is apparent from the description of the present embodiment, according to the present invention, a method for driving a piezoelectric ink jet head using a shearing mode is used, and selective simultaneous printing using m nozzles is possible. 2m because it can be realized by using m + 1 bipolar transistors and m diodes
The drive circuit can be simplified as compared with the prior art which requires a single bipolar transistor.

(Embodiment 2) (1) A second embodiment of the present invention will be described below with reference to the drawings. The structure of the print head in this embodiment is the same as that in the first embodiment.
Is the same as. As shown in FIG. 11, the common electrode 141 is connected to the positive power supply line. The common discharging pnp bipolar transistor 248 has an emitter connected to the positive power supply line, and a collector connected in a reverse direction to the collector to separate diodes 251, 252, 253, 254.
Via the drive electrodes 121, 122, 123, 1 respectively.
24 is connected. The drive electrodes further include npn bipolar transistors 241, 242, 24 for charging, respectively.
Connected to the collectors of 3, 244 and the emitter of the npn bipolar transistor is grounded.

(2) Now, as shown in the timing chart of FIG. 10, with the period T and the pulse width τ, the r-th (r is 1,
It is an arbitrary number among 2, 3, and 4. ) Np for charging
n bipolar transistors 241, 242, 243, 2
A channel selection signal Qpr and a control signal Qnn rising at a pulse width τ are simultaneously added to the base of 44 and the base of a discharging pnp bipolar transistor 248, respectively.
During the period of τ when the signal rises, the npn bipolar transistor is made conductive, the pnp bipolar transistor is made nonconductive, and the npn bipolar transistor is made nonconductive and the pnp bipolar transistor is made conductive in other periods. While the channel selection signal is rising, the r-th drive electrode is electrically connected to the ground, while the common electrodes 141, which are arranged on both sides of the electrode and serve as the opposite electrodes of the capacitor, are connected to the positive power supply line. As a result, a current flows into the capacitor and the capacitor is charged and the voltage P of the drive electrode becomes a low potential of the ground level with respect to the potential of the common electrode.

As a result, two wall surfaces on both sides of the injection groove are formed.
An electric field is applied from the outside to the inside of the capacitors formed by the individual drive partition walls 115, and an inward shearing force is generated on the partition walls on both sides, and the partition walls are deformed inward as shown in FIG. 4 to compress and eject the ink in the grooves. Droplets are discharged from the holes 110. Next, after the period τ has passed, a positive power supply line for the capacitor and a discharging pnp bipolar transistor 2
48, a discharge loop is formed between the dummy electrode and the drive electrode via the diodes 251, 252, 253, 254, and the discharge is performed, and the voltage P of the drive electrode becomes equal to the voltage of the dummy electrode and becomes a positive power supply level. The electric field in the drive partition 115 disappears, and the drive partition returns to the original state. (3) In this way, also in this embodiment, as a result, the same printing operation as in the first embodiment is performed, and the same effect is obtained.

(Embodiment 3) Next, a third embodiment of the present invention will be described. The present embodiment is an embodiment of the present invention in a print head of a system in which a lid of a pressure chamber filled with ink is deformed by utilizing a flexure of a piezoelectric element in a bending mode.
In FIGS. 15A and 15B, a substrate 301 is provided with a first groove 302 forming a pressure chamber, a second groove 303 forming an ejection groove, and a third groove 304 introducing ink. ing. The second groove 303 is aligned and opened on one end surface of the substrate. A nozzle plate 305 is attached to the end face, and an injection hole 308 corresponding to the injection groove 303 is provided in the nozzle plate. A thin plate 306 is placed on the upper surface of the substrate.
, And the piezoelectric element 307 is attached to the upper surface of the thin plate in correspondence with the first groove 302, thereby forming the head 300. If one electrode of each piezoelectric element is connected to form a common electrode and the opposite electrode serves as a drive electrode, the equivalent circuit becomes a parallel circuit of capacitors as shown in FIG. 8 and is shown in FIG. 1 and described in the first embodiment. The piezoelectric element is selectively driven simultaneously by the driving method or the method similar to that described in the second embodiment shown in FIG. 11, the ink in the selected pressure chamber is compressed, and the ink is ejected from the ejection hole to perform printing. be able to.

(Embodiment 4) (1) A method of arranging a plurality of print heads shown in FIG. 2 and described in Embodiment 1 and performing time division driving of a plurality of groups by a common drive circuit with one head as one group Will be explained. As shown in FIG. 12, the dummy electrodes 128 in the group are connected to form common electrodes 141, 142,
, 143, and the common electrodes for each group correspond to the group drivers 451, 452, respectively.
It is connected to the ground via 453 .... Each of the group drivers is composed of npn bipolar transistors 411, 412, 413, ... And diodes 421, 422, 423 ,. The emitter is connected to ground and the collector is connected to the common electrode of the corresponding group.

The first drive electrode 121 of each group is the first pnp bipolar transistor 43 for charging.
1 collector, 2nd one is pnp for 2nd charging
In the collector of the bipolar transistor 432, the third one is the third pnp bipolar transistor 4 for charging.
33 collector, 4th is pn for 4th charging
Each of them is connected to the collector of the p bipolar transistor 434. The emitters of these pnp bipolar transistors for charging are connected to the positive power supply line. The first drive electrode 121 of each group is the first for separation.
Through the diode 471, the second through the second diode 472, the third through the third diode 473, and the fourth through the fourth diode 474. Np for common discharge
It conducts in the forward direction to the collector of the n-bipolar transistor 450. The emitter of the discharging npn transistor 450 is grounded.

(2) Now, as shown in the timing chart of FIG. 13, the group selection signals Qg1, Qg2, Qg3 and Qg4 which rise with the pulse width τ in the cycle T are sequentially (1/4) T.
With the phase shift of npn bipolar transistors 411, 412, 413, ... Of the first, second, third and fourth group drivers of FIG. Conduction during the period and non-conduction during the other periods. The r-th (r is an arbitrary number among 1, 2, 3, 4) pnp bipolar transistor base for charging and n for discharging
Channel selection signals Qpr and Qnn which rise at a pulse width τ are added to the base of the pn bipolar transistor at the same time and in synchronization with the group selection signal. During the period of τ when the signal rises, the charging pnp bipolar transistor is turned on and discharged. The npn bipolar transistor is turned off, and the charging pnp bipolar transistor is turned off and the discharging npn bipolar transistor is turned on during other periods.

During the period when the channel selection signal rises, the r-th drive electrode 121 in the group selected corresponding to that period is electrically connected to the positive power supply line, and is arranged on both sides of the electrode. Since the common electrode (141 or the like) forming the opposite electrode of the capacitor is electrically connected to the ground, current flows into the capacitor for charging, and the potential P of the drive electrode 121 becomes higher than the potential of the common electrode.
As a result, an electric field is applied from the inner side to the outer side of the capacitors formed by the two drive partition walls 115 forming the wall surfaces on both sides of the injection groove, and a shear force toward the outer sides is generated on the partition walls on both sides, and the drive partition is shown in FIG. As described above, the ink is sucked into the groove by deforming outward. Next, after the period τ has passed, a diode (4) for isolation is provided between the drive electrode 121 and the dummy electrode.
71 etc.), npn bipolar transistor 45 for discharging
0, ground and group driver diode (421
, Etc., the discharge loop is turned on, the discharge is performed, the voltage P of the drive electrode becomes the ground level, the electric field in the drive partition 115 disappears, and the drive partition rapidly returns to the original state. At this time, the ink in the groove is compressed and droplets are ejected from the ejection holes 110.

When the above-mentioned channel selection signal rises, the inflow of current from the selected drive electrode to the non-selected drive electrodes is blocked by the separating diode (471 etc.) in the same group. Since the r-th drive electrode of the unselected group also conducts to the positive power source through the selected charging transistor, it also shunts from the capacitor associated with the electrode through the other capacitor of the group connected to it. Since a charging flow path is formed by capacitors other than the r-th capacitor in the selected group, which are electrically connected to these respectively through connecting lines, all capacitors other than the r-th capacitor in the selected group are indicated by arrows, for example. 3 as illustrated
Charging is performed in a state where the individual capacitors are connected in series, and so-called crosstalk voltage is generated between the two electrodes of these capacitors, but these voltages are all 1/2 or less of the positive power supply voltage. Therefore, if the positive power supply voltage is set so that the minimum voltage required for ejecting ink is ½ or more of the power supply voltage, printing crosstalk is prevented and drive independence is maintained. In this way, it is possible to perform printing by selecting nozzles of a plurality of groups in a time-division manner and based on print data by using a common drive circuit.

(3) According to the present invention as exemplified in the present embodiment, m × n nozzles can be driven by n time division using m + n + 1 bipolar transistor switching means. This is mx in the conventional n time division method.
It requires 2m + n + 1 bipolar transistors or the like to drive n nozzles, but has the advantage of simplifying the drive circuit. Although this embodiment relates to a time-division driving method of the present invention for a piezoelectric ink jet head using a shear mode, the same applies to a piezoelectric ink jet head using a bending mode as shown in the third embodiment. The time division drive according to the present invention can be performed.

Next, a technique for completely removing the generation of the crosstalk voltage will be described as a reference example in this embodiment. As shown in FIG. 14, the first drive electrode 121 of each group is the collector of the first charging pnp bipolar transistor 431, and the second one is the collector of the second charging pnp bipolar transistor 432. To three
The fourth one is on the collector of the third charging pnp bipolar transistor 433 and the fourth one is on the collector of the fourth charging pnp bipolar transistor 434, respectively, and the diodes 441, 442, 443 and 4 for charging are respectively provided.
Connected via 44. The connection direction of this diode is the forward direction from the collector of the pnp transistor to the electrode. The emitters of these pnp bipolar transistors for charging are connected to the positive power supply line. The first drive electrode 121 of each group is the first one for discharge.
Through the diode 445, the second through the second diode 446, the third through the third diode 447, and the fourth through the fourth diode 448. Np for common discharge
It conducts in the forward direction to the collector of the n-bipolar transistor 450. The other structure is similar to that of the embodiment shown in FIG.

Now, the group selection signal and the channel selection signal as shown in the timing chart of FIG.
For a selected group driver npn bipolar transistor (411, etc.) and a selected pnp bipolar transistor (43) for charging.
1) and the like, they become conductive, and the drive electrode of the selected channel of the selected group is charged through the diode (441 etc.) for charging, and the voltage of the drive electrode is charged. P is raised to a positive power supply voltage, and as a result, the partition of the ejection groove is widened and ink is sucked. Next, after the period τ has passed, the drive electrode 121
Between the common electrode and the discharge diode (445, etc.),
Since the discharge loop is conducted through the discharging npn bipolar transistor 450, the ground and the diode (421 etc.) of the group driver, the discharging is performed, the voltage P of the driving electrode becomes the ground level, and the electric field in the driving partition wall 115 is changed. It disappears and the drive partition quickly returns to its original state. At this time, the ink in the groove is compressed and droplets are ejected from the ejection holes 110. Here, during the period τ during which the selection signal rises, the drive electrodes of the non-selected groups are charged as a result of the charging diodes (442 and the like) preventing charging due to the sneak through via the adjacent capacitor. Absent. Further, in the selected group, charging of channels not selected by the discharging diodes (446, etc.) is blocked. As a result, according to this example, no crosstalk voltage is generated, only the drive electrode of the selected channel of the selected group becomes the voltage of the positive power supply, and the other drive electrodes are held at the ground level voltage. . Therefore, the power supply voltage can be set sufficiently high with respect to the minimum voltage required for ejecting ink, and the reliability of operation is improved.

[0028]

【The invention's effect】

(1) According to the method for driving an inkjet head of the present invention, the number of switch means in the drive circuit required to selectively drive and print a plurality of nozzles in a piezoelectric inkjet head at the same time is almost the same as in the prior art. Since it can be halved, the drive circuit can be simplified. (2) The drive circuit can be simplified without using time-division driving, which is advantageous in increasing the printing speed. (3) By incorporating the time-divisional driving in the present invention, a more remarkable simplification of the drive circuit can be realized as compared with the conventional time-divisional driving. (4) In the embodiment, the case where the bipolar transistor is used as the switch means in the present invention has been described.
The same effect can be obtained not only by this but also when other switching means such as FET is used.

[Brief description of drawings]

FIG. 1 is a diagram showing a circuit used in a driving method according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view showing the structure of the head according to the first embodiment of the present invention.

FIG. 3 is a sectional view showing an operation of a partition wall of the head in the first embodiment of the present invention.

FIG. 4 is a sectional view showing an operation of a partition wall of the head in the second embodiment of the present invention.

FIG. 5 is a perspective view showing the structure of the head in the first embodiment of the present invention.

FIG. 6 is a diagram showing an equivalent circuit of the head according to the first embodiment of the present invention.

FIG. 7 is a diagram showing another equivalent circuit of the head in the first embodiment of the invention.

FIG. 8 is a diagram showing an equivalent circuit of a head according to a third embodiment of the present invention.

FIG. 9 is a time chart showing a driving method according to the first embodiment of the present invention.

FIG. 10 is a time chart showing a driving method according to a second embodiment of the present invention.

FIG. 11 is a diagram showing a circuit used in a driving method according to a second embodiment of the present invention.

FIG. 12 is a diagram showing a circuit used in a driving method according to a fourth embodiment of the present invention.

FIG. 13 is a time chart showing a driving method according to a fourth embodiment of the present invention.

FIG. 14 is a circuit diagram of a reference example relating to a fourth example of the present invention.

FIG. 15 is a diagram showing a structure of a head according to a third embodiment of the present invention. FIG. 7A is a front view showing the structure of the head in the third embodiment of the present invention. FIG. 9B is a side view showing the structure of the head in the third embodiment of the present invention.

[Explanation of symbols]

 41 pnp bipolar transistor 42 pnp bipolar transistor 43 pnp bipolar transistor 44 pnp bipolar transistor 48 npn bipolar transistor 51 diode 52 diode 53 diode 54 diode 101 substrate 103 elastic member 104 lid 105 head 108 nozzle plate 110 injection hole 111 injection groove 112 dummy groove 115 Drive partition wall 121 Ejection electrode 128 Dummy electrode 141 Common electrode 142 Common electrode 143 Common electrode 181 Ink supply groove 182 Joint 241 npn bipolar transistor 242 npn bipolar transistor 243 npn bipolar transistor 244 npn bipolar transistor 248 pnp bipolar transistor 251 diode 252 Iodine 253 Diode 254 Diode 301 Substrate 302 First groove 303 Jet groove 304 Ink supply groove 305 Nozzle plate 306 Thin plate 307 Piezoelectric element 411 npn bipolar transistor 412 npn bipolar transistor 413 npn bipolar transistor 414 npn bipolar transistor 421 diode 4 diode 422 diode pnp bipolar transistor 432 pnp bipolar transistor 433 pnp bipolar transistor 434 pnp bipolar transistor 441 diode 442 diode 443 diode 444 diode 445 diode 446 diode 447 diode 448 diode 450 npn bipolar transistor 451 guru Up driver 452 group driver 453 group driver 471 diode 472 diode 473 diode 474 diode

Claims (4)

[Claims] 1. A substrate made of a piezoelectric material having a plurality of grooves forming a pressure chamber and a partition thereof and a common groove communicating with the plurality of grooves and supplying ink, wherein the plurality of grooves of the substrate are provided. A nozzle plate having ejection holes for ejecting ink is attached to the open end face, electrodes for piezoelectric driving are attached to the plurality of grooves, and a drive voltage is applied to the electrodes to deform the partition wall in a shear mode. In an inkjet head that changes the volume of the pressure chamber and ejects the ink filled in the pressure chamber from the ejection holes, ejection grooves that eject ink and dummy grooves that do not eject ink are provided alternately, and the electrodes of the ejection grooves are driven independently. Electrodes, electrodes in the dummy groove are connected to each other to form a common electrode, and a switch means for charging is provided between one terminal of the power source and an independent drive electrode for each drive electrode. A common electrode is connected to one of the terminals, an independent drive electrode is connected to the other terminal of the power source through a diode for separation and a common switch means for discharging, and selectively by charge switch means. A method for driving an inkjet head, wherein the capacity of the piezoelectric element of the partition wall is charged and the discharge is performed by a common discharging switch means. 2. In an ink jet head having a plurality of nozzles, the nozzles being deformed by piezoelectric driving to eject ink in the nozzles, one electrode of a piezoelectric element driving each of the plurality of nozzles is independently driven. As the electrode, the other electrode is connected between the nozzles as a common electrode, and a switch means for charging is provided between one terminal of the drive power source and an independent drive electrode in correspondence with each drive electrode. The common electrode is connected to the other terminal of the power source, and the independent drive electrode is connected to the other terminal of the power source through the diode for separation and the common switch means for discharging, and the switch means for charging selectively A method for driving an inkjet head, wherein the capacity of the piezoelectric element is charged, and the discharging is performed by a common discharging switch means. 3. A substrate made of a piezoelectric material having a plurality of grooves forming a pressure chamber and a partition thereof and a common groove communicating with the plurality of grooves and supplying ink, wherein the plurality of grooves of the substrate are provided. A nozzle plate having an ejection hole for ejecting ink is attached to the open end face, electrodes for piezoelectric drive are attached to the plurality of grooves, and a partition wall is deformed in a shear mode by applying a drive voltage to the electrodes. In an inkjet head that changes the volume of the pressure chamber and ejects the ink filled in the pressure chamber from the ejection holes, ejection grooves that eject ink and dummy grooves that do not eject ink are provided alternately, and these groove rows are time-divided. Divide into groups, the electrodes of the plurality of ejection grooves are independent drive electrodes, the electrodes of the dummy grooves of the same group are connected to each other to form a common electrode, and one electrode of the power source and each independent drive electrode are connected to each other. Switch means for charging is provided corresponding to the order of arrangement of the drive electrodes in the loop, and a group driver is provided between the other terminal of the power source and the common electrode for each group to provide independent drive electrodes. It is connected to the other terminal of the power source through a separating diode and a common discharging switch means, and is selectively switched by a charging switch means for each group of groove rows selected in time division by a group driver. A method for driving an inkjet head, wherein the capacity of the partition wall is charged, and the discharging is performed by a common discharging switch means. 4. An ink jet head having a plurality of nozzles, wherein the nozzles are deformed by piezoelectric drive to eject ink in the nozzles, the plurality of nozzles are divided into time-division groups, and each of the plurality of nozzles is driven. One electrode of the piezoelectric element is used as an independent drive electrode, the other electrode is connected to each group as a common electrode, and the drive electrodes in each group are arranged between one terminal of the drive power supply and the independent drive electrode. A switch means for charging is provided corresponding to the above, a group driver is provided between the other terminal of the power source and the common electrode for each group, and an independent drive electrode is provided for the diode and the common discharge electrode. It is connected to the other terminal of the power source via a switch means, and a switch hand for charging is provided for each group of nozzles selected in a time division manner by a group driver. A method for driving an ink jet head, wherein the capacity of the piezoelectric element is selectively charged by steps, and the discharge is performed by a common discharging switch means.