JPH09123445A - Ink jet head driver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance the image quality by canceling a residual pressure fluctuation in an ink chamber in accordance with characters different in each ink color of ink. SOLUTION: A unit 80 generates a yellow ink jet pulse and a cancellation pulse which cancels out a residual pressure fluctuation in a yellow ink chamber. In this case, a pulse edge detection circuit 84 which detects the edge of a jet pulse, a register 86 which sets a cancellation pulse generation position an a pulse width count in accordance with the character of the yellow ink, a counter 87 which counts said set pulse widths from a time when a pulse edge is detected, are provided, and when the count reaches a set count, the cancellation pulse is caused by a cancellation pulse generation circuit 85.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for driving an ink jet head of an ink jet printer which ejects ink onto a printing medium to perform printing, and the ink chamber remains after the voltage is applied to the piezoelectric element. The present invention relates to a suitable drive device that cancels pressure fluctuations and performs high-quality printing.

[0002]

2. Description of the Related Art First, the structure and operation of an ink jet head will be described with reference to FIGS. FIG.
Is a structural diagram of a shear mode type inkjet head,
6 to 8 are partial cross-sectional views of the ink chambers constituting the inkjet head shown in FIG. 5, and FIG. 9 is a drive waveform generated from the drive device, displacement of the partition walls of the ink chambers, and pressure near the nozzles. Waveform timing charts are shown respectively.

As shown in FIG. 5, the ink jet head 10 comprises a piezoelectric ceramic plate 12, a cover plate 14, a nozzle plate 16 and a substrate 18. A plurality of grooves 20 are formed on the piezoelectric ceramic plate 12 by cutting with a diamond blade or the like. The partition walls 22 forming the side portions of each groove 20 are polarized in the direction of the arrow F1, and each groove 20
Have the same depth and are parallel between the grooves.

The depth of each groove 20 gradually becomes shallower as it approaches the rear end face 24 of the piezoelectric ceramic plate 12, and a shallow groove 26 is formed near the rear end face 24. A thin-film metal electrode 28 is formed on the upper half of each side of each groove 20 by sputtering or the like.
The thin-film metal electrode 30 is formed on the side surface and the bottom surface of the shallow groove 26.
Are formed by sputtering or the like. As a result, the metal electrodes 28 formed on both side surfaces of the groove 20 are electrically connected to the metal electrodes 30 formed in the shallow groove 26.

The cover plate 14 is made of a ceramic material, a resin material, or the like, and the ink inlet 37 and the manifold 32 are formed by cutting or the like. The upper surface of the piezoelectric ceramic plate 12 (the surface on which the groove 20 is processed) and the cover plate 1
The lower surface of 4 (the surface on the side where the manifold 32 is processed) is adhered by an epoxy adhesive. As described above, by covering the upper opening surface of the groove 20, as shown in FIG.
As shown in, a plurality of ink chambers 40 having the same interval in the lateral direction are formed. Each ink chamber 40 has an elongated shape with a rectangular cross section, and all the ink chambers 40 are filled with ink.

As shown in FIG. 5, a nozzle plate 16 is adhered to the front end faces of the piezoelectric ceramic plate 12 and the cover plate 14, and the nozzle plate 16 is provided at a position corresponding to the position of each ink chamber 40. , Nozzles 38 are provided respectively. The nozzle plate 16 is made of a synthetic resin material.

A substrate 18 is bonded to the lower surface of the piezoelectric ceramic plate 12 (the surface opposite to the side where the groove 20 is processed) with an epoxy adhesive or the like. On the substrate 18, a pattern 34 of a conductive layer is formed corresponding to each ink chamber 40, and the pattern 34 and the shallow groove 26 are formed.
The metal electrode 30 is connected by a conductive wire 36 by wire bonding.

Next, the ink jet head 1 having the above structure
The operation of 0 will be described with reference to FIGS. 6 and 7. Before the drive voltage is applied to the metal electrodes 28, 28, each partition 2
2 is in the state shown in FIG. In FIG. 7, the ink chamber 4
When the ink is ejected from 0c, the metal electrode 28b
And 28c, a positive drive voltage V is applied to the metal electrode 28
a and 28d are grounded. The partition wall 22a has an arrow F2.
A driving electric field in the direction of arrow F3 is generated, and the partition wall 22b has an arrow F3.
A driving electric field in the direction of is generated. Then, the driving electric field direction F
Since 3 and F4 are orthogonal to the polarization direction F1 (see FIG. 5), the partition walls 22a and 22b are rapidly deformed inside the ink chamber 40c as shown in FIG. 7 due to the piezoelectric thickness slip effect. . Due to this deformation, the volume of the ink chamber 40c decreases, and the ink pressure rapidly increases,
A nozzle 3 that generates a pressure wave and communicates with the ink chamber 40c
Ink is ejected from 8 (see FIG. 5).

When the application of the drive voltage V is stopped, the partition walls 22a and 22b return to the state before deformation shown in FIG. 6, so that the ink pressure in the ink chamber 40c gradually decreases. Then, ink is introduced into the ink chamber 40c from an ink tank (not shown) through the ink introduction port 37 and the manifold 32 (see FIG. 5). In order to improve the efficiency of ink ejection, the polarization direction F1
By applying a positive voltage with F2 (see FIG. 6) reversed, first, as shown in FIG.
And 22b are deformed away from each other and then
By stopping the application of voltage, the partition walls 22a and 22a
A drive device has been proposed that returns 2b to the state before deformation and ejects ink.

The behavior of the pressure wave for ink ejection in each ink chamber 40 when using such a driving device will be described with reference to FIG. The polarization direction of the partition wall 22 is downward as shown by the arrow F2. First, the ink chamber 4
A drive voltage is applied to the metal electrodes 28b and 28c to eject ink from 0c. Then, the partition walls 22a and 22b are deformed so as to be separated from each other by the rise of the driving voltage, the volume of the ink chamber 40c increases, and the pressure in the ink chamber 40c including the vicinity of the nozzle 38 decreases. The state is maintained for the time represented by L / a. Then, during that time, ink is supplied from the manifold 32 (see FIG. 5) into the ink chamber 40c. At this time, the pressures of the ink chambers 40b and 40d increase, but since only one partition wall is deformed, the ink is not ejected from that ink chamber.

Further, in the above L / a, the pressure wave in the ink chamber 40c is the longitudinal direction of the ink chamber 40c (the manifold 3).
2 is the time required to propagate in the direction toward the nozzle plate 16 or vice versa.
It is determined by the length L of c and the sound velocity a in the ink. According to the propagation theory of the pressure wave, when the time of L / a has just passed from the above rise, the ink chamber 40
Although the pressure in c reverses to positive pressure, the voltage applied to the ink chamber 40c is set to 0V at this timing.

Then, the partitions 22a and 22b return to the state before deformation (FIG. 6), and pressure is applied to the ink.
At that time, the positive pressure and the partition walls 22a and 22a
The pressure generated by the return of c to the state before deformation is added, and a relatively high pressure is generated in the portion of the ink chamber 40c near the nozzle 38, and the ink is ejected from the nozzle 38.

When printing is performed on a printing medium using the above driving device, it is impossible to eject ink simultaneously from at least the adjacent ink chambers 40 due to its structure. Therefore, for example, as described in Japanese Patent Application Laid-Open No. 2-150355, a device is used in which the ink chambers 40 are divided into two groups of odd-numbered ones and even-numbered ones and ejected alternately. Further, in the case where such a device is used, when the crosstalk, which is the mutual interference between the ink chambers 40, is large, as a method of improving the crosstalk, the ink chambers 40 each having (n-1) ink chambers 40 are provided. An apparatus has been proposed in which the ink chambers 40 are divided into n (n is 3 or more) groups including them and are sequentially applied with a drive voltage to the ink chambers 40 of each group by rotation.

Here, the fluctuation of the residual pressure will be described. When the driving is performed in groups of three or more as described above, the following problems occur. That is, in FIG. 8, for example, when ink is ejected from the ink chamber 40c, the partition wall 22a of the ink chamber 40c.
And 22b are deformed, but the partition wall 22a is also the partition wall of the ink chamber 40b at the same time, and the partition wall 22b is also the partition wall of the ink chamber 40d at the same time.
A pressure wave is also generated in d.

The pressure wave in each of the ink chambers 40b to 40d propagates in each ink chamber using ink as a medium, is reflected at the end of the ink chamber 40, and is attenuated while repeatedly reciprocating in the ink chamber 40. go. Therefore, even after the ink ejection, the pressure fluctuation due to the pressure wave remains in each ink chamber 40 for a while. This is the so-called residual pressure fluctuation.

If the next ink ejection is performed in the ink chamber 40d, the original ink ejection pressure and the above-mentioned residual pressure fluctuation are added in the ink chamber 40d, and the flying speed of the ink is increased. And injection characteristics such as volume are different from those when there is no residual pressure fluctuation. In addition, the ink chamber 40
The residual pressure fluctuation due to the ink ejection of c differs depending on the print pattern. Therefore, in this case, the ink chamber 40d
Since the ink ejection characteristics of the ink change depending on the print pattern, stable ejection cannot be performed. Further, since the ink is ejected sequentially from the ink chambers 40 of one group, all the ink chambers except the ink chambers 40 at both ends of the inkjet head (which do not belong to the above group and do not eject ink). At 40, the above-mentioned inconvenience occurs.

On the other hand, for example, JP-A-62-299.
As disclosed in Japanese Patent No. 343, it is considered to reduce the residual pressure fluctuation in the ink chamber 40 by applying a cancel pulse subsequent to a print pulse for ejecting ink. That is, after a lapse of a certain time from the ink ejection, a cancel pulse for generating a pressure wave whose phase is opposite to the residual pressure fluctuation in the ink chamber 40 is applied. With this device, the ink chamber 40
By applying the print pulse and the cancel pulse to c, the residual pressure fluctuation in the ink chambers 40b to 40d can be canceled at the same time.

Here, cancellation of pressure wave fluctuation and residual pressure fluctuation during ink ejection in each ink chamber 40 will be described with reference to FIG. First, in order to eject ink from the ink chamber 40c of FIG.
A positive injection voltage pulse C shown in FIG. Then, as shown in FIG.
At the rising edge of, the partition walls 22a and 22b are deformed so as to be separated from each other (see FIG. 9C). Thereby,
As the volume of the ink chamber 40c increases, as shown in FIG. 9D, the pressure in the vicinity of the nozzle 38 of the ink chamber 40c (hereinafter,
Unless otherwise specified, the pressure in the ink chamber 40 refers to the nozzle 3
8) shall be meant). This state is maintained for the above time L / a (see FIG. 9A). Then, in the meantime, the manifold 32 (see FIG. 5)
Ink is supplied into the ink chamber 40c.

After the lapse of time L / a, the applied voltage to the ink chamber 40c is returned to 0V as shown in FIG. 9 (a).
Then, the partition walls 22a and 22b return to the state before deformation shown in FIG. 6, and pressure is applied to the ink. At that time, as described above, the pressures are added, a relatively high pressure Pc as shown in FIG. 9D is applied to the ink in the ink chamber 40c, and the ink is ejected from the nozzle 38. After the ink is ejected, if a new voltage pulse is not applied to the ink chamber 40c, the pressure of the ink chamber 40c becomes 2L / a as a cycle as shown by the solid line in FIG.
It keeps changing for a while. This is the residual pressure fluctuation.

On the other hand, the above-described series of operations is performed by the ink chamber 40c.
When viewed from the ink chamber 40d adjacent to the
Since only b deforms in the opposite direction to that seen from the ink chamber 40c, the vicinity of the nozzle 38 of the ink chamber 40d is shown in FIG.
As shown by the solid line in FIG. 9, a pressure fluctuation whose phase is opposite to that in FIG. 9D and whose amplitude is half appears. Although not shown, the same applies to the ink chamber 40a.

Next, after the ink is ejected from the ink chamber 40c, the ejection voltage pulse D shown in FIG. 9B, for example.
Is given to the ink chamber 40d to eject ink.
At the time when the pulse D is applied, the residual pressure fluctuation still exists in the ink chamber 40d as shown in FIG. 9E, and therefore the pressure fluctuation after the pulse D is applied in FIG.
This is different from the pressure fluctuation when there is no residual pressure fluctuation shown by the solid line in FIG.

Therefore, the cancel pulse K shown by the broken line in FIG. 9A is applied to the ink chamber 40c after L / a from the trailing edge of the ejection pulse C. The width of the cancel pulse K is L / a and the polarity is negative, which is the opposite of the polarity of the ejection pulse C. Further, the voltage value is set according to the amplitude of the residual pressure fluctuation so that the fluctuation is just canceled. By applying the cancel pulse K, the partition walls 22a and 22b are deformed in the opposite manner to that at the time of ink ejection, and a pressure wave having a phase opposite to the residual pressure fluctuation is applied to cancel the residual pressure fluctuation. That is, as indicated by a broken line in FIGS. 9D and 9E, the pressure of the ink in the ink chamber 40d is set to 0 before the voltage pulse D is applied.

Next, a drive circuit for realizing the cancellation of the residual pressure fluctuation will be described with reference to FIG. The output signals X, Y, and Z shown in FIG.
It is an output signal for setting the voltage applied to the metal electrode 28 of 0 to V, 0, -V / 2. When the output signal X turns ON,
Voltage pulse for ejecting ink (C, D in FIG. 9)
Generate. Further, when the output signal Z is turned on, a voltage pulse (K in FIG. 9) for causing pressure fluctuation for cancellation is generated. In other cases, the output signal Y is turned on and the output voltage is set to 0. C1 represents an equivalent capacitance component constituted by the partition wall 22 of the ink chamber 40 and the metal electrodes 28 formed on both sides of the partition wall 22.

The drive circuit is composed of three blocks surrounded by a broken line, each of which is an injection charging circuit 832, a discharging circuit 833 and a canceling pressure generating circuit 835. Then, when the output signal is turned on, the transistor T2 becomes conductive, and the voltage V is applied from the positive power source 831 to the electrode E of the capacitor C1 via the resistor R6. When the output signal Y is turned on, the transistor T3 becomes conductive and the electrode E of the capacitor C1 is grounded via the resistor R6.
When the output signal Z turns on, the transistor T6
Is conducted, and a voltage of −V / 2 is applied from the negative power source 836 to the electrode E of the capacitor C1 via the resistor R6.

[0025]

By the way, since the above inks have different properties such as viscosity, density, surface tension, etc. depending on the color, even if the same ejection pulse is applied to the ink chamber, the volume of the ink chamber is changed. The amount of increase and the speed of increase are different. Therefore, it is desirable that the timing at which the cancel pulse is applied to the ink chambers is matched with the timing at which the ejection pulse is applied to each ink chamber. However, since the above-mentioned conventional one applies exactly the same cancel pulse to the ink heads of all colors, it is not possible to cancel the residual pressure fluctuation efficiently, and it is possible to perform high-quality printing according to the ink color. There is a problem that you cannot do it.

Therefore, the present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide an ink jet head driving device capable of performing high-quality printing according to the color of ink. To do.

[0027]

In order to achieve the above object, the present invention provides an ink chamber containing ink, a nozzle for ejecting the ink, and a pressure in the ink chamber. Is a driving device of an ink jet head in which a head provided with a piezoelectric element for changing the ink is provided in plural for each color of the ink, and the pressure of the ink chamber is changed by driving the piezoelectric element by applying a voltage. In the ink jet head drive device for ejecting ink from the nozzles to the printing medium, it is a voltage signal that cancels the pressure fluctuation of the ink chamber that occurs after the voltage is applied to the piezoelectric element. A canceling signal for outputting a canceling signal having the characteristics respectively set to the piezoelectric element after a predetermined time has passed from the voltage application. Adopt the technical means that with an output means.

According to a second aspect of the invention, in the ink jet head drive device according to the first aspect, the cancellation signal output means is provided with a cycle setting means for setting a cycle of the cancellation signal. Adopt technical means.

According to a third aspect of the invention, in the ink jet head drive device according to the first or second aspect,
The canceling signal output means employs a technical means in which a voltage setting means for setting the voltage of the canceling signal is provided.

According to a fourth aspect of the present invention, in the ink jet head drive device according to any one of the first to third aspects, the cancellation signal output means has a rising edge of a waveform of the cancellation signal, or The technical means that a waveform gradient setting means for setting the falling gradient is provided is adopted.

[0031]

According to the present invention, the voltage signal for canceling the pressure fluctuation of the ink chamber generated after the voltage is applied to the piezoelectric element is a characteristic set according to the properties of the ink of each color. Since it is a cancellation signal having, it is possible to cancel the pressure fluctuation of the ink chamber in consideration of the property of the ink. Therefore, high-quality color printing can be performed according to the individual properties of the color ink.

In particular, according to the second aspect of the invention, since the cycle of the canceling signal can be set, it is possible to apply the canceling signal of the cycle corresponding to the difference in the ink density to the piezoelectric element. . Therefore, good quality printing can be performed even when the density differs depending on the color of the ink.

According to the third aspect of the invention, since the voltage of the cancellation signal can be set, the cancellation signal having a voltage corresponding to the difference in the viscosity (viscosity) of the ink is applied to the piezoelectric element. Can be applied. Therefore, good quality printing can be performed even when the viscosity is different depending on the color of the ink.

Further, in the invention described in claim 4, since it is possible to set the rising or falling slope of the waveform of the cancellation signal, the cycle of the cancellation signal and the rising of the voltage can be set to the ink level. Fine adjustments can be made according to complex differences such as density and viscosity. Therefore, even when the density or the viscosity is different depending on the color of the ink, it is possible to print with higher quality.

[0035]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the main configuration of an inkjet head drive device (hereinafter, abbreviated as drive device) of the present invention.

As shown in FIG. 1, an ink jet head 70 to which the main drive device 60 is connected is a yellow head 72 for ejecting yellow ink, a magenta head 74 for ejecting magenta ink, and a cyan head. The head 76 for cyan ejects ink and the head 78 for black ejects black ink. Since the structure of each head is the same as that of the conventional one (see FIG. 5), description thereof will be omitted.

The ink jet head 10 is mounted on a carriage that reciprocates in the width direction of the printing paper by driving a step motor, and this carriage reads a position gauge provided along the moving direction of the carriage. An encoder 120 is attached. The output of the encoder 120 is connected to the MPU 130 that performs the calculation for the carriage position control and the calculation of the ink ejection timing of each head.
The MPU 130 is connected to the main drive unit 60.

Next, the structure of the main drive unit 60 will be described. Since the drive devices connected to the respective heads are basically the same, here, the yellow head 7 is used.
The drive device 80 of No. 2 will be described as a representative. The drive device 80 is provided with a trigger generation circuit 81 that generates a trigger in accordance with the injection timing calculated by the MPU 130. The trigger generation circuit 81 receives the trigger output from the trigger generation circuit 81. A pulse generation circuit 82 that generates a pulse for injection is connected.

The pulse generating circuit 82 receives the ejection pulse output from the pulse generating circuit 82 and converts it into a signal for driving the head 72.
It is connected to the. The pulse generation circuit 82 is connected to a pulse edge detection circuit 84 that detects the edge (starting point) of the ejection pulse output from the pulse generation circuit. In this pulse edge detection circuit 84,
A voltage signal that cancels pressure fluctuations in the ink chamber that occur after voltage is applied to the head 72, and that has a characteristic set according to the nature of the yellow ink (hereinafter,
A cancel pulse generating circuit 85 that generates a cancel pulse) is connected. In this example, a circuit such as a one-shot multivibrator or flip-flop is preferably used as the pulse edge detection circuit 84. The configuration of the drive circuit 83 is the same as that shown in FIG.
The description is omitted because it is the same as that shown in FIG.

Further, the present driving device 80 is provided with a register 86 in which the position where the cancel pulse is generated and the pulse width of the cancel pulse are set. The register 86 is connected to a counter 87 that counts from the time when the pulse edge detection circuit 84 detects the edge of the ejection pulse. That is, the counter 87 is
The pulse edge detection circuit 84 counts at the timing at which the edge of the ejection pulse is detected, and when the count number reaches the count number set in the register 86, the cancel pulse generation circuit 85 outputs the cancel pulse. Occur.

Now, the injection pulse and the cancel pulse will be described with reference to FIG. Injection pulse J
10 is set to the pulse width T1. This T1 is
It is the same value as L / a described above, that is, a value determined by the length L of the ink chamber 40c and the sound velocity a in the ink. The pulse width T2 of the cancel pulse K10 is determined based on the ink density. That is, since the density of the ink varies depending on the color, the pulse width T2 has a different value for each color of the ink. In the case of high density ink, the pulse width T2 is set small and in the case of low density ink Sets a large pulse width T2.

The rising timing, that is, the cycle of the cancel pulse K10 is determined by the time A from the edge J11 of the injection pulse J10, and the falling timing is set in the register 86 but the pulse width T2.
Is determined by That is, the time A is set small for the ink having a high density, and the times A and B are set large for the ink having a low density. The setting of the time A is changed by changing the set value of the register 86. Further, instead of the pulse width T2, the fall time B of the cancel pulse K10 from the edge J12 of the ejection pulse J10 is set in the register 86, and the rise and rise of the cancel pulse K10 is set by the above times A and B. It is also possible to determine the fall timing.
At this time, the setting of the time B is changed by changing the set value of the register 86.

Further, the voltage value V of the cancel pulse K10
The size of 1 is set based on the ink viscosity (viscosity). That is, since the viscosity of ink is different for each color, the voltage value V1 is different for each color of ink. For ink having a large viscosity, the voltage value V1 is set to be large and the ink having a small viscosity is used. In this case, the voltage value V1 is set small.

Further, the fine adjustment based on the density and viscosity of the ink can be performed by changing the slopes of the rising portion D and the falling portion E of the cancel pulse K10. That is, the speed of pressure change can be controlled by adjusting the resistance R6 of FIG. 10 to change the slopes of the rising portion D and the falling portion E.

Next, the operation of the drive unit 80 will be described with reference to FIG.
Or, it demonstrates with reference to FIG. First, when print data is transmitted from a host computer (not shown) and a carriage equipped with an inkjet head is driven, position data of the carriage is read by the encoder 120.

Then, the read position data is
It is input to the MPU 130 and used as position data of the injection pulse. When an injection command is issued from the MPU 130, a trigger is generated from the trigger generation circuit 81, and this trigger is input to the injection pulse generation circuit 82 and shaped into a pulse waveform for injection. This ejection pulse is input to the drive circuit 83 and converted into the ejection pulse J10 shown in FIG. The ejection pulse J10 is applied to the head 7
2 is given to the ink chamber, and the volume of the ink chamber increases,
Ink is ejected when the ink chamber returns to the state before the deformation (see FIGS. 8 and 9).

Next, when the ejection pulse J10 is generated from the ejection pulse generation circuit 82, its edge (rising timing) J11 is the pulse edge detection circuit 8
4 and the counter 87 starts counting the time A in accordance with the detection. Then, at the timing when the count number A stored in the register 86 is reached, the cancel pulse generation circuit 85 cancels the cancel pulse K1.
0 (see FIG. 2) is generated to cancel the residual pressure fluctuation in the ink chamber.

As described above, according to the driving device of the embodiment of the present invention, since it is possible to generate the cancel pulse according to the property that is different for each color of the ink, it is possible to obtain the high quality corresponding to the color of the ink. Printing can be performed. In addition,
The configurations of the driving device 90 for driving the magenta head 74, the driving device 100 for driving the cyan head 76, and the driving device 110 for driving the black head 78 are the same as those of the driving device 80.

Next, a drive device according to a second embodiment of the present invention will be described with reference to FIGS. 3 and 4. The drive device according to the present embodiment was proposed by the present applicant in the previous application (Japanese Patent Application Laid-Open No. 7-156388), and is characterized by a canceling pressure generating circuit to which only a positive power source is connected. To cancel the residual pressure fluctuation. FIG. 3 is an explanatory diagram of the ejection pulse and the cancel pulse used in the drive device, and FIG. 4 is a circuit diagram of the drive circuit used in the drive device.

The change in the ink chamber when using this drive circuit is as follows. In FIG. 6, a positive ejection pulse is applied to the metal electrodes 28b and 28c.
, The volume of the ink chamber 40c is increased (first
Step), the application of the injection pulse is stopped, and the state before deformation shown in FIG. 6 is restored (second step). Then, the ink chambers 40b and 40 on both sides of the ink chamber 40c.
A positive cancel pulse (denoted by K20 in FIG. 3) is applied to d to reduce the volume of the ink chamber 40c (third step), and then the application of the ejection pulse is stopped as shown in FIG. The state before the deformation shown in FIG. 6 is restored (fourth step).

A typical time from the start of the second step to the end of the third step (shown by B in FIG. 3)
By making the pressure wave generated in the ink in the ink chamber within 0.5 time the one-way propagation time in the ink chamber, the residual pressure fluctuation can be canceled. The pulse width T2 of the cancel pulse K20 and the voltage value V
1, cycle A, pulse rise D and fall E
The inclination and the like are set according to the properties such as the viscosity, density and surface tension of the ink, as in the first embodiment. As described above, according to the drive device of the present embodiment, the residual pressure fluctuation can be canceled by the single drive source, and the drive circuit can be simplified, so that the reliability of the drive circuit is improved. Also, the manufacturing cost can be reduced.

In each of the above embodiments, the drive circuit 83, the pulse edge detection circuit 84, the cancel pulse generation circuit 85, the register 86 and the counter 87.
Corresponds to the cancellation signal output means of the present invention. Further, the register 86 serves as a negative power source 83 for the cycle setting means of the present invention.
6 and the positive power source 831 correspond to the voltage setting means, and the resistor R6 corresponds to the waveform gradient setting means.

[0053]

As described above, according to the present invention, it is possible to cancel the residual pressure fluctuation in the ink chamber by generating the cancel pulse according to the property that is different for each color of ink, so that the quality of color printing is improved. Can be increased.

[Brief description of the drawings]

FIG. 1 is a block diagram of a drive device according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram showing an injection pulse and a negative cancel pulse.

FIG. 3 is an explanatory diagram showing an injection pulse and a positive cancel pulse.

FIG. 4 is a circuit diagram of a drive circuit that generates a positive cancel pulse.

FIG. 5 is a structural diagram of an inkjet head driven by a driving device according to the present invention.

6 is a cross-sectional explanatory view showing an ink chamber before deformation of the inkjet head shown in FIG.

7 is an ink chamber 4 of the inkjet head shown in FIG.
It is a section explanatory view showing the state where the volume of 0c decreased.

8 is an ink chamber 4 of the inkjet head shown in FIG.
It is a section explanatory view showing the state where the volume of 0c increased.

FIG. 9A is a timing chart of a positive ejection voltage pulse C applied to the metal electrodes 28b and 28c. (B) is a timing chart of the positive injection voltage pulse C applied to the metal electrodes 28d and 28e. (C) is a timing chart showing the displacement of the partition wall 22b. (D) is a timing chart showing pressure fluctuations near the nozzle 38 located in the ink chamber 40c. (E) is a timing chart showing pressure fluctuations near the nozzle 38 located in the ink chamber 40d.

FIG. 10 is a circuit diagram of a drive circuit that generates a negative cancel pulse.

[Explanation of symbols]

 10 Inkjet Head 12 Piezoelectric Ceramic Plate 14 Cover Plate 16 Nozzle Plate 18 Substrate 20 Groove 22 Partition Wall 28 Metal Electrode 37 Ink Inlet 38 Nozzle 40 Ink Chamber 60 Drive Device

Claims (4)

[Claims] 1. An ink jet head having a plurality of heads each including an ink chamber containing ink, a nozzle for ejecting the ink, and a piezoelectric element for changing the pressure of the ink chamber, the head being provided for each color of the ink. In the inkjet head drive device for driving the piezoelectric element by applying a voltage to change the pressure of the ink chamber and eject ink from the nozzle to the printing medium, the piezoelectric element is driven by a voltage. A voltage signal that cancels pressure fluctuations in the ink chamber that occur after being applied, and a canceling signal that has characteristics that are set according to the properties of the inks of the respective colors is generated after a predetermined time has elapsed from the voltage application. An ink jet head drive device comprising a cancellation signal output means for outputting to an element. 2. The ink jet head driving device according to claim 1, wherein the canceling signal output means is provided with a cycle setting means for setting a cycle of the canceling signal. 3. The ink jet head drive device according to claim 1, wherein the cancellation signal output means is provided with voltage setting means for setting the voltage of the cancellation signal. 4. The cancellation signal output means is provided with a waveform gradient setting means for setting a rising or falling gradient of a waveform of the cancellation signal. The inkjet head drive device according to any one of 1.