JPH10119260A - Ink jet head and its driving method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent or reduce fluctuation of a meniscus owing to cross talk in a piezoelectric type ink jet having a plurality of pressure chambers discharging ink and a common liquid chamber interconnected to the pressure chamber. SOLUTION: In an ink jet, a piezoelectric element for correction 15 controlling a meniscus is attached onto an outer wall 3a of a common liquid chamber, and the outer wall 3a is deformed by driving the piezoelectric element for correction 15 to enlarge and reduce a volume of a common liquid chamber 3 in sychronism with pressurizing and sucking operations of the pressure chamber 5. Fluctuation in pressure of the common liquid chamber is absorbed thereby to prevent or reduce fluctuation of the meniscus owing to cross talk of propagation of fluid pressure between the pressure chambers 5. Thereby, a size of a liquid drop of discharged ink is uniformized, and quality of recording can be improved.

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 an on-demand type piezoelectric ink jet head.

[0002]

2. Description of the Related Art On-demand type printers using a piezoelectric ink jet head have advantages such as simple structure, relatively high speed, low noise recording, and easy color recording. It's being used. Such an ink jet head performs recording by intermittently discharging ink from the pressure chambers based on a drive signal. In order to increase the recording speed, it is general to provide a large number of pressure chambers in one ink jet head. is there. It has a plurality of pressure chambers and a common liquid chamber communicating with the pressure chambers. The outer wall of the pressure chambers is deformed by piezoelectric driving of the piezoelectric element, and ink is ejected from nozzle holes communicating with the pressure chambers to perform printing or the like.

[0003]

However, in an ink jet head in which a plurality of pressure chambers are integrally formed, there is a problem that the meniscus fluctuates due to the interference between the pressures, thereby causing crosstalk. This type of crosstalk will be described with reference to the drawings. FIG. 8 is a view showing a conventional piezoelectric ink jet head. It has a plurality of pressure chambers and a common liquid chamber communicating with the pressure chambers, deforms the outer wall of the pressure chambers by piezoelectric driving of the piezoelectric element, and performs recording such as printing by discharging ink from nozzle holes communicating with the pressure chambers. .

In a head having such a structure, when the outer wall of the pressure chamber in which ink is to be ejected is deformed to pressurize the pressure chamber to eject ink, the increased pressure in the ink chamber causes the flow of the ink and the pressure wave. Is caused to increase the pressure of the liquid chamber of the common liquid chamber, and the pressure further increases the pressure of other ink chambers by the same principle, thereby pushing out the meniscus. At that time, when the ink is ejected to the other ink chamber, a droplet larger than normal is ejected.

After the ejection, the piezoelectric element is driven to suck ink from the common liquid chamber into the pressure chamber, and the pressure chamber is enlarged and decompressed by restoring the outer wall of the ink chamber. This causes the pressure in the other pressure chambers to drop through the pressure drop in the common liquid chamber, thereby pulling in the meniscus. Therefore, the meniscus may not be restored by the next ejection, and a droplet smaller than normal may be ejected.

[0006] The meniscus fluctuates due to the crosstalk as described above. In some cases, the meniscus is pushed out, and in some cases, the meniscus is pulled in and the size of the droplet to be ejected is fluctuated. In general, the fluctuation of the meniscus depends on the recording pattern.In some patterns, the droplets are large, and in another pattern, the droplets are small. Is significantly reduced.

As one of the solutions to this problem, there is a method in which the common liquid chamber is made sufficiently large to prevent pressure fluctuation. However, the problem is that the common liquid chamber becomes extremely large and the head becomes large. Besides, when the pressure chambers are close to each other, the fluctuations in the pressure are transmitted to each other via the local fluctuations in the pressure in the common liquid chamber, so that a sufficient effect cannot be obtained.

Another method is disclosed in Japanese Patent Application Laid-Open No. Hei 6-312513.
As described in the publication, a part of the inner surface of the common liquid chamber is used as an ink-repellent surface 106, and a bubble 107 is held in this portion, and the bubble 107 absorbs fluctuations in the pressure of the common liquid chamber, thereby reducing crosstalk. There is known a technique for preventing a meniscus from fluctuating. However, although the bubble 107 is stable when the ink is at rest, it tends to swing and deform as the ink flows. And, as the frequency of the ink flow increases, for example, as in the case of ultrasonic cleaning, when the vibration becomes strong, bubbles are deformed, separated, split, etc., blocking the inlet of the pressure chamber, preventing ink suction. Is also possible. This is disadvantageous in performing high-speed recording.

As still another method, there is a method in which an elastic body, a porous body, or the like is provided in a common liquid chamber to absorb pressure fluctuation. However, such a method is disadvantageous for miniaturization of the head, easily generates fine dust such as a porous body, and easily causes a problem such as clogging a nozzle hole.

The present invention solves the above-mentioned problems of the prior art, prevents or reduces meniscus fluctuation due to crosstalk, is excellent in recording quality such as printing quality, and is compact and suitable for high-speed recording on demand. It is an object to provide a piezoelectric ink jet head of a mold type.

[0011]

As a means for solving the above-mentioned problems, the present invention has a plurality of pressure chambers and a common liquid chamber communicating with the pressure chambers, and the outer wall of the pressure chambers is driven by piezoelectric driving. In an ink jet head that performs deformation and discharges ink from nozzle holes communicating with the pressure chambers to perform printing,
A compensation piezoelectric member for controlling meniscus is attached to an outer wall of the common liquid chamber.

According to the present invention, a plurality of pressure chambers and a common liquid chamber communicating with the pressure chambers are provided, and an outer wall of the pressure chambers is deformed by piezoelectric driving, and ink is ejected from a nozzle hole communicating with the pressure chambers. A piezoelectric member for controlling meniscus is attached to the outer wall of the common liquid chamber of the inkjet head that performs printing by printing, and the common liquid chamber is expanded in synchronization with or almost in synchronization with the pressurizing operation of the pressure chamber for discharging ink. Then, the correcting piezoelectric member is driven so as to reduce the common liquid chamber in synchronization with or almost in synchronization with the pressure reducing operation of the pressure chamber for sucking the ink. This makes it possible to absorb fluctuations in the pressure of the common liquid chamber caused by the pressurizing operation and the depressurizing operation of the pressure chamber, and prevent or reduce fluctuations in meniscus due to crosstalk.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION

(Embodiment 1) A first embodiment of the present invention will be described below with reference to the drawings. 1 and 2 are cross-sectional views showing an example of an ink jet head to which the present invention is applied.

A common liquid chamber 3 communicating with the ink supply port 2 and a plurality of pressure chambers 5 connected to the common liquid chamber 3 and having orifices 4 are formed in the flow path forming member 1. A pressure chamber 5 and a diaphragm 6 forming an outer wall 3a of the common liquid chamber 3 are attached to the lower surface of the flow path forming member 1. The pressure chamber 5 is a portion surrounded by a diaphragm 6 bonded to the flow path forming member 1 with an adhesive and a pressure chamber wall 7, and the common liquid chamber 3 is surrounded by the diaphragm 6 and a common liquid chamber wall 8. Part. The laminated piezoelectric element unit 9 is formed by joining a laminated piezoelectric member to a base 10 made of an insulating material with an epoxy adhesive or the like, and then forming a groove 11 to a predetermined depth of the base 10 by wire working or the like to thereby collect a drive member. It is configured as an aggregate of a plurality of pressure chamber piezoelectric elements 14 on which the electrodes 12 and the common collector electrode 13 are formed. The correcting piezoelectric element 15 is bonded to the outer wall 3a of the diaphragm 6 forming the common liquid chamber 3, and the frame 16 is bonded to the outer wall of the diaphragm 6 forming the pressure chamber 2 and the orifice 4 using an adhesive.

The front end faces of the flow path forming member 1, the diaphragm 6 and the frame 16 are made to be on the same plane, and a nozzle plate 17 is provided on this plane. The nozzle plate 17 is provided with nozzle holes 18 for ejecting ink droplets, and each of the nozzle holes 18 communicates with the pressure chamber 5.

The driving collector 12 and the common collector 13 of the pressure chamber piezoelectric element 14 are positioned so that the conductive pattern of the flexible printed circuit board 19 and the driving collector 12 and the common collector 13 coincide with each other. Later
The heater is pressed from the surface and fused with solder or the like, and a voltage is applied from an external circuit (not shown). As a result, a potential difference occurs between the internal electrodes 14a and 14b, and the piezoelectric material sandwiched therebetween is deformed in the thickness direction. With this deformation, the diaphragm 6 is deformed, and changes the volume in the pressure chamber 5. As a result, the ink supplied into the pressure chamber 5 is ejected from the nozzle holes 18.

The driving of the pressure chamber piezoelectric element 14 is performed by a known method. A part or all of the plurality of pressure chamber piezoelectric elements 14 are selected based on the print data, and the selected pressure chamber piezoelectric elements 14 are simultaneously driven by applying or releasing a voltage, and the corresponding outer wall of the pressure chamber 5 is pressed. Is deformed, and ink is ejected by pressurization. By driving the piezoelectric element 14 for the pressure chamber in the opposite direction by applying or releasing a voltage to the pressure chamber 5 after the discharge, the outer wall of the pressure chamber 5 is deformed in the opposite direction, and the common liquid chamber is depressurized. Ink suction from 3 and filling. Here, the pressure chamber piezoelectric element 14 operates in the d33 mode. That is, the outer wall of the pressure chamber 5 expands and contracts in the stacking direction by application and release of the voltage, and deforms in the vertical direction.

The correcting piezoelectric element 15 joined to the outer wall 3a of the common liquid chamber 3 operates in the d31 mode, expands and contracts in the length direction by applying a driving voltage, and deforms the outer wall 3a of the common liquid chamber 3 in the bending mode. . That is, when a voltage is applied between the electrodes of the correcting piezoelectric element 15 and the length of the element is extended, the outer wall 3a of the diaphragm 6 is deformed downward and the volume of the common liquid chamber 3 is enlarged. When a voltage is applied in the opposite direction, the length of the correcting piezoelectric element 15 is reduced, the outer wall 3a is deformed to be convex upward, and the volume of the common liquid chamber 3 is reduced.

In this embodiment, the piezoelectric element 14 for the pressure chamber is used.
Is driven to pressurize the pressure chamber 5 and apply or apply a voltage in the direction in which the element extends to the electrode of the correcting piezoelectric element 15 synchronously or almost synchronously when ink is ejected and ejected. As a result, the volume of the common liquid chamber 3 is increased, and even if the ink flows backward from the pressure chamber 5 to the common liquid chamber 3 due to the pressurization of the pressure chamber 5, the rise in the pressure of the common liquid chamber 3 due to this is absorbed or reduced. Can be done.

After the ink is ejected from the pressure chamber 5, the pressure chamber piezoelectric element 14 is driven to move the outer wall of the pressure chamber 5 in the opposite direction, and the pressure is reduced so that the ink is sucked and filled from the common liquid chamber 3. In this embodiment, a voltage is applied to the electrodes of the correcting piezoelectric element 15 in synchronization with or substantially in synchronization with the suction operation so that the length of the element is reduced or restored. As a result,
Even if the volume of the common liquid chamber 3 is reduced and the ink flows out of the common liquid chamber 3 toward the pressure chamber 5 due to the decompression of the pressure chamber 5, it is possible to prevent or limit the decrease in the pressure of the common liquid chamber 3 due to this. it can.

In this embodiment, the fluctuation of the pressure in the common liquid chamber 3 can be prevented or reduced during the discharge and suction of the ink in the pressure chamber 5, and thus the fluctuation of the meniscus due to the crosstalk can be prevented. Or it can be reduced.

The method of driving the head in this embodiment will be described more specifically with reference to the drawings. FIG. 3 is a diagram showing a drive circuit of an ink jet head and a control circuit thereof according to the present invention. Reference numeral 31 denotes a shift register which sequentially shift-records serial data as recording data in response to a clock signal CL1, and includes a plurality of stages of D-FFs. The parallel output line of this register is connected to a latch circuit 32 having a plurality of stages of D-FFs. The parallel output line of the latch circuit 32 is connected to one input terminal of an AND gate 33 provided in the same number as the number of recording drive circuits for driving the pressure chamber piezoelectric elements 14. A common enable signal line 34 is connected to the other input terminals of these AND gates 33. The enable signal line 34 is further connected via a delay circuit 35 and a NOT circuit 36 to a control terminal 38 of a later-described correction drive circuit 37 for driving the correction piezoelectric element 15. The output line of the AND gate 33 is connected to a control terminal 39 of a recording drive circuit 40 described later.

A principle diagram of the recording drive circuit 40 and the correction drive circuit 37 is shown in the frame of the dotted line in FIG. Each recording drive circuit 4
0 connects one electrode of the pressure chamber piezoelectric element 14 to the high potential side of the drive power supply via the charge switch 41 and connects to the low potential side of the drive power supply via the discharge switch 42;
It is configured by connecting the other electrode of the pressure chamber piezoelectric element 14 directly to the low potential side of the drive power supply. Reference numerals 38 and 39 denote switch control terminals, to which control signals are inputted to turn on / off the charge switch 41 and the discharge switch 42.
Perform FF. Similarly, the correction drive circuit 37 connects one electrode of the correction piezoelectric element 15 to the high potential side of the drive power supply via the charge switch 41 and also connects to the low potential side of the drive power supply via the discharge switch 42. The other electrode of the piezoelectric element 15 is directly connected to the lower potential side of the driving power supply. The recording drive circuit 4 is also provided in the correction drive circuit 37.
A control terminal 39 similar to 0 is provided.

Next, the operation of the above control circuit and drive circuit will be described. FIG. 4 is a time chart showing the operation of the circuit shown in FIG. 3 and changes in the capacities of the pressure chamber and the common liquid chamber. As shown in FIG. 4, the voltages V1 of all the switch control terminals 39 of the recording drive circuit 40 are initially set to L, whereby the charge switch 41 is turned on and the discharge switch 42 is turned off.
State. Further, the voltage V2 of the switch control terminal 38 of the correction drive circuit 37 is set to H, whereby the charge switch 41 is turned off and the discharge switch 42 is turned on. At this time, the power supply voltage V is applied to all the pressure chamber piezoelectric elements 15, the heights of the elements are reduced from their natural lengths by the d33 effect, and the volumes S1 of all the pressure chambers 5 are expanded by ΔS. Further, the voltage V applied to the correcting piezoelectric element 15 is zero due to the discharge, the length of the correcting piezoelectric element 15 remains the natural length, and the outer wall 3a of the common liquid chamber 3 is not deformed. And keep it. Therefore, FIG.
As shown in (2), the change in the volume S2 of the common liquid chamber 3 is zero.

After resetting by applying a reset signal to the reset terminal of the shift register 31, serial data as recording data is added to the data line, and shift recording is sequentially performed in the register by the clock signal CL1. Next, a latch signal is applied to the latch circuit 32, and the parallel output of the shift register 31 is held in the latch circuit 32. Next, the enable signal p1 applied to the enable signal line 34 rises from L to H. At this time, when the data held in the bit of the latch circuit 32 is H, the output of the connected AND gate 33 becomes H, and the output of the AND gate 33 connected to the L bit of the held data becomes L. When the output of the AND gate 33 becomes H, the voltage V1s of the switch control terminal 39 of the corresponding recording drive circuit 40 changes from L to H, the charge switch 41 is switched from ON to OFF, and the discharge switch 42 is switched from OFF to ON. Switching, piezoelectric element for pressure chamber 1
4, the applied voltage VC1S is reduced to zero, the height of the element is restored, the volume S1s of the corresponding pressure chamber 5 is reduced and restored by ΔS1, the pressure is applied to the pressure chamber 5, and ink is ejected from the nozzle hole 18. Let it. On the other hand, when the output of the AND gate 33 is L, the output of the switch control terminal 39 remains L,
The charge switch 41 is turned on, the discharge switch 42 is kept off, and the pressure chamber piezoelectric element 14 is reduced.
Maintain the state expanded by ΔS1, and the pressure chamber 5 does not discharge ink. In this manner, ink is ejected only to the pressure chamber 5 selected by the print data.

The output of the delay circuit 35 changes from L to H slightly after the rise of the enable signal, and the correction control voltage V2 of the switch control terminal 38 of the correction drive circuit 37 falls from H to L. As a result, the charge switch 41 is turned off.
From F to ON, the discharge switch 42 switches from ON to OFF, the voltage VC2 applied to the correcting piezoelectric element 15 becomes the driving voltage V, and expands the piezoelectric element, thereby increasing the volume S2 of the common liquid chamber 3 according to the principle described above. Enlarge by ΔS2. The expansion of the common liquid chamber 3 is performed at a slightly different timing from the timing of the reduction and restoration of the pressure chamber 5. This corresponds to the fact that the backflow of the ink to the common liquid chamber 3 is started slightly shifted from the start of the reduction of the pressure chamber 5. In this way, an increase in the pressure of the common liquid chamber 3 due to ink ejection is effectively prevented or reduced.

Next, the signal p1 of the enable signal line 34 becomes H
When the voltage falls from L to L, the outputs of the AND gates 33 connected to all the recording drive circuits 40 become L, and in the previously selected recording drive circuit 40, the voltage V1s of the switch control terminal 39 falls from H to L. As a result, the charge switch 41 is switched from OFF to ON and the discharge switch 42 is switched from ON to OFF, and the voltage VC1s applied to the pressure chamber piezoelectric element 15 becomes V.
Is increased by ΔS 1, and the pressure is reduced. The ink is sucked from the common liquid chamber 3 and filled in the pressure chamber 5 to prepare for the next ejection.

The output of the delay circuit changes from H to L slightly after the fall of the enable signal P1, and the correction driving circuit 3
7, the voltage V2 of the switch control terminal 38 is raised from L to H. As a result, the charge switch 41 is changed from ON to OFF.
, The discharge switch 42 switches from OFF to ON,
The voltage VC2 applied to the correction piezoelectric element 15 is reduced to zero by discharging, and the common liquid chamber 3 is reduced and restored by ΔS2. The contraction and restoration of the common liquid chamber 3 are performed slightly different from the large timing of the pressure chamber 5. This corresponds to the fact that the outflow of the ink from the common liquid chamber 3 to the pressure chamber 5 is slightly shifted from the start of the expansion of the pressure chamber 5. In this manner, a decrease in the pressure of the common liquid chamber 3 due to ink ejection is effectively prevented or reduced.

(Embodiment 2) A second embodiment of the present invention will be described. The print head itself used in this embodiment is the same as that of the first embodiment, except that a method of driving the piezoelectric element for correction and a control circuit related thereto are different. FIG. 5 is a diagram showing another embodiment of the drive circuit and the control circuit used in this embodiment. A description will be given of points different from the circuit of the first embodiment shown in FIG. Reference numeral 51 denotes a first counter, which sequentially counts the number of H data out of serial data as print data, and integrates and records the data. The first counter 51 includes a plurality of T-FFs. 52 is a second counter, which is a control clock pulse CL2.
Are sequentially counted and integrated and recorded, and are constituted by a plurality of stages of T-FFs. A clock signal line 54 for outputting a clock signal CL1 to the shift register 53 is branched and connected to one input terminal of an AND gate 55, and a data line 56 to the shift register 53 is branched and connected to the other input terminal. . The output line of the AND gate 55 is connected to the first counter 5
1 input terminal.

The match detection circuit 57 has a first counter 51
And the second counter 52 receives a parallel output.
The output line of the coincidence detection circuit 57 is connected to the input terminal of the storage circuit 58. The storage circuit 58 uses a one-stage T-FF whose output switches at the rise of a signal. The output line of the storage circuit 58 is connected to the inverting input terminal of the NAND gate 59. The output line of the delay circuit 60 is connected to the other normal input terminal of the NAND gate 59. The output line of the NAND gate 59 is connected to the first switch control terminal 62 of the correction drive circuit 66. The output line of the delay circuit 60 is branched and connected to the second switch control terminal 63 of the correction drive circuit 66. The output line of the delay circuit 60 is branched and connected to one input terminal of the AND gate 64. Signal line 65 for outputting control clock pulse CL2
Is connected to the other input terminal of the AND gate 64. The output line of the AND gate 64 is connected to the input terminal of the second counter 52. For the correction drive circuit 66, the charge switch 67
Is connected to the high potential side of the drive power supply via a resistor R, the charge switch 67 is controlled by the first switch control terminal 62, and the discharge switch 6 is controlled by the second switch control terminal 63.
8 is controlled. The rest is the same as in the first embodiment.

Next, the operation of the circuit, the pressure chamber, and the common liquid chamber in this embodiment will be described. FIG. 6 is a time chart showing the operation of the circuit shown in FIG. 5 and a change in volume of the pressure chamber and the common liquid chamber. Initially, as shown in FIG.
0, the voltage V1 of all control terminals 39 is set to L, whereby the charge switch 67 is turned ON and the discharge switch 68 is turned OFF.
The state is set to F. In addition, by setting the signal voltage of the inverting input terminal and the normal input terminal of the NAND gate 59 to L, the voltage V21 of the first control terminal 62 of the correction drive circuit 66 is set to H, thereby turning the charging switch 67 OFF.
The state is set to F, the voltage V22 of the second control terminal is set to L, and thereby the discharge switch 68 is turned on. At this time, the applied voltage to all the pressure chamber piezoelectric elements 14 becomes the power supply voltage V, the height of the elements is reduced from the natural length by the d33 effect, and the volumes S1 of all the pressure chambers 5 are expanded by ΔS1. Keep it. Further, the voltage VC2 applied to the correcting piezoelectric element 15 is in a zero state due to the discharge,
The length of the correction piezoelectric element 15 is kept at its natural length, and the outer wall of the common liquid chamber 3 is kept in an undeformed state. That is,
The change amount of the volume S2 of the common liquid chamber 3 is zero. This state is the same as in the first embodiment.

At the same time as applying a reset signal to the reset terminal of the shift register, a reset signal is applied to the first counter 51, the second counter 52, and the storage circuit 58 to reset them. After resetting, serial data as recording data is added to the data line 56, and the clock signal CL
1 is sequentially shifted and recorded in the shift register 53.
At this time, a counting pulse is simultaneously input from the AND gate 55 to the first counter 51, but this counting pulse is generated only when the serial data input to the shift register 53 is H and not generated when the serial data is L. Therefore, the first counter 51 counts the number of data in the H state among the data input to and held in the shift register 53, that is, the number of bits in the H state among the bits of the shift register 53. Will be retained. Next, a latch signal is applied to the latch circuit 69. Next, when the enable signal voltage p1 is raised from L to H on the enable signal line 34, only the pressure chamber 5 selected by data as in the first embodiment has its volume. The pressure chamber 5 is pressurized by reducing and restoring S1s by ΔS1, and the ink is ejected from the nozzle hole 18.

The output of the delay circuit 44 rises from L to H slightly after the rise of the enable signal P1, and is input to the normal input terminal of the NAND gate 59. At this time, the storage circuit 5 input to the inverting input terminal of the NAND gate 59
8, the output of the NAND gate 59 changes from H to L, and the voltage V21 of the first switch control terminal 62 of the correction drive circuit 66 is changed to L.
Falls from H to L. As a result, the charge switch 67 is
Switching from FF to ON. On the other hand, the voltage V22 of the second switch control terminal 63 rises from L to H, and the discharge switch 68
Switches from ON to OFF. As a result, a current flows from the power supply to the correction piezoelectric element 15 through the charging resistor R, and charging is started. Then, the voltage VC2 applied to the correcting piezoelectric element C2 increases with time according to the charging time constant. As a result, the increase ΔS2 in the volume S2 of the common liquid chamber 3
Also increase almost in proportion to time. On the other hand, simultaneously with the rise of the delay circuit 60, the control clock pulse CL2 of the signal line 65 is input to the second counter 52 through the AND gate 64, and the second counter 52 counts the control clock pulse CL2. When the count value matches the count value already held in the first counter 51, the match detection circuit 57 generates a detection pulse.
When the detection pulse is input to the storage circuit 58, the output is changed from L to H and the state is maintained.

Here, the counting operation of the second counter 52 is completed while the output of the delay circuit 60 is constantly rising and while the charging voltage VC2 is increasing linearly with time. Done. When the output of the storage circuit 58 rises to H, the output of the NAND circuit 59 becomes L again.
To H, and the voltage V21 of the first switch control terminal 62 becomes H, so that the charge switch 67 is turned from ON to OFF.
And charging stops. On the other hand, at this time, the voltage V22 of the second control terminal 63 is H, and the discharge switch 68 is maintained in the OFF state. Therefore, after that, until the output of the delay circuit 60 falls, the correction piezoelectric element 1
5 and the increase ΔS2 of the volume S2 of the common liquid chamber 3 are kept constant. Assuming that the final applied voltage is VC2s and the final volume increase is ΔS2s,
Both VC2s and ΔS2s are substantially proportional to the time during which charging is performed, that is, the time TL during which the output of the NAND circuit 59 is at L. Since TL is equal to the counting time of the second counter 52 until the coincidence signal is generated, the number of H data counted and held by the first counter 51, that is, the number of pressure chambers 5 that eject ink at the same time, is calculated. Proportional. Therefore, the expansion of the volume of the common liquid chamber 3 in proportion to the number of the pressure chambers 5 that simultaneously ejects ink is maintained during a period in which the enable signal 34 rises. The volume S2 of the common liquid chamber 3 is increased in proportion to the number of the pressure chambers 5 for simultaneously discharging ink, substantially corresponding to the period in which the pressure chamber 5 is contracted. Can be ideally prevented from increasing.

Next, as described above, the enable signal p1 falls, the selected pressure chamber 5 expands, and ink is sucked. On the other hand, the output of the delay circuit 60 falls slightly after the fall of the enable signal p1, and the voltage V of the second control terminal 63 of the correction drive circuit 66 is reduced.
22 is changed from H to L. As a result, the discharge switch 66 is switched from OFF to ON, but the output of the NAND gate 59 remains H and the charge switch 63 is OFF, so that the correction piezoelectric element 15 is discharged and the common liquid chamber 3 is discharged. The volume S2 of the pressure chamber 5 is restored by reducing the above-mentioned increase in volume by ΔS2s, and at the same time, the volume is reduced in proportion to the number of pressure chambers 5 for discharging ink. Can be ideally prevented.

As described above, according to the present embodiment, even if the number of pressure chambers 5 for simultaneously ejecting ink changes, fluctuations in the pressure of the common liquid chamber 3 during ink ejection and suction are ideally prevented. This can prevent the meniscus from fluctuating due to crosstalk, make the liquid droplets uniform, and significantly improve recording quality such as printing quality.

(Embodiment 3) Next, a third embodiment of the present invention will be described. In the present embodiment, two correction piezoelectric elements are provided on the outer wall of the common liquid chamber 3 of the head, and the driving of each is controlled by a method similar to the second embodiment. FIG. 7 is a plan sectional view showing the structure of an ink jet head according to another embodiment to which the present invention is applied. The common liquid chamber 3 has a structure provided with a partition 3b. The correction piezoelectric element 15a is bonded to the outer wall 3a in the left area, and the correction piezoelectric element 15b is bonded to the right area. Each correction piezoelectric element 1
FPCs (not shown) are formed on the electrodes 5a and 15b by using a conductive agent.
Connected to 19 leads.

The deformation of the outer wall 3a of the common liquid chamber 3 is controlled at two places. Thereby, the deformation of the common liquid chamber 3 can be controlled in a form corresponding to the pressure chamber 5 that discharges from a location. That is, since the outer wall 3a of the common liquid chamber 3 is deformed in the vicinity of the pressure chamber 5 to be discharged in accordance with the number thereof, the pressure of the common liquid chamber 3 is controlled to be always uniform even in place, and the meniscus is controlled. Can be prevented, and the uniformity of the droplets can be further improved.

[0039]

As described above, according to the present invention, the fluctuation of the meniscus due to crosstalk is prevented or reduced.
It is possible to provide an on-demand type piezoelectric inkjet head which is excellent in recording quality such as printing quality and is small and suitable for high-speed recording.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an example of the structure of an ink jet head to which the present invention is applied.

FIG. 2 is a cross-sectional view illustrating an example of the structure of an inkjet head to which the present invention is applied.

FIG. 3 is a diagram showing a driving circuit of an ink jet head and a control circuit thereof according to the present invention.

FIG. 4 is a time chart showing the operation of the circuit and the change in the capacity of the pressure chamber and the common liquid chamber in the embodiment shown in FIG. 3;

FIG. 5 is a diagram showing another embodiment of the drive circuit and the control circuit used in the present embodiment.

FIG. 6 is a time chart showing the operation of the circuit and the change in the volume of the pressure chamber and the common liquid chamber in the embodiment shown in FIG. 5;

FIG. 7 is a plan sectional view showing the structure of an ink jet head according to another embodiment to which the present invention is applied.

FIG. 8 is a cross-sectional view illustrating a structure of a conventional inkjet head.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Flow path forming member 2 Ink supply port 3 Common liquid chamber 3a Outer wall 3b Partition wall 4 Orifice 5 Pressure chamber 6 Diaphragm 7 Pressure chamber wall 8 Common liquid chamber wall 9 Multilayer piezoelectric element unit 10 Base 11 Groove 12, 13 Electrode 14 Pressure chamber Piezoelectric element for correction 15 Piezoelectric element for correction 16 Frame 17 Nozzle plate 18 Nozzle hole 19 FPC 31, 53 Shift register 32, 69 Latch circuit 33, 55, 64 AND gate 34 Enable signal line 35, 60 Delay circuit 36 NOT circuit 37, 66 Correction drive circuit 38, 39 Switch control terminal 40 Recording drive circuit 41, 67 Charge switch 42, 68 Discharge switch 51 First counter 52 Second counter 53 Shift register 54 Clock signal line 56 Data line 57 Match detection circuit 58 Storage circuit 59 Nandgate 60 Slow Extension circuit 62 First switch control terminal 63 Second switch control terminal 65 Signal line

Claims (4)

[Claims] 1. A pressure chamber having a plurality of pressure chambers and a common liquid chamber communicating with the pressure chambers, wherein an outer wall of the pressure chamber is deformed by piezoelectric driving, and ink is ejected from nozzle holes communicating with the pressure chambers to perform printing. In the ink jet head, a correction piezoelectric member for controlling a meniscus is attached to an outer wall of the common liquid chamber. 2. A pressure chamber having a plurality of pressure chambers and a common liquid chamber communicating with the pressure chambers, wherein an outer wall of the pressure chambers is deformed by piezoelectric driving, and printing is performed by discharging ink from nozzle holes communicating with the pressure chambers. A piezoelectric member for controlling the meniscus is attached to the outer wall of the common liquid chamber of the ink jet head, and the common liquid chamber is expanded and synchronized with the pressurizing operation of the pressure chamber for discharging ink, and ink is sucked. A method for driving an ink jet head, comprising: driving a correcting piezoelectric member so as to reduce a common liquid chamber in synchronization with or substantially in synchronization with a pressure reducing operation of a pressure chamber. 3. The method according to claim 2, wherein the driving voltage of the correcting piezoelectric member is controlled in accordance with the number of pressure chambers that simultaneously perform a discharging operation. 4. A printing apparatus having a plurality of pressure chambers and a common liquid chamber communicating with the pressure chambers, deforming an outer wall of the pressure chambers by piezoelectric driving, and discharging ink from nozzle holes communicating with the pressure chambers to perform printing. A plurality of correction piezoelectric members for controlling the meniscus are attached to the outer wall of the common liquid chamber of the ink jet head, and synchronized with the pressurizing operation of the pressure chamber for discharging ink,
Alternatively, the correction piezoelectric member is driven so that the common liquid chamber is expanded substantially in synchronization with the pressure reducing operation of the pressure chamber for sucking ink, or is reduced substantially in synchronization with the pressure chamber. A method for driving an ink-jet head, wherein a drive voltage applied to each of the correcting piezoelectric members is independently controlled in accordance with the number of pressure chambers simultaneously discharged in the vicinity of the member.