JPH11138797A - Ink-jet printer head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the reduction in the velocity and quantity of ejected ink particles by reducing a cross stroke by controlling the second pressure element to displace in the opposite direction to the first piezoelectric element when the first piezoelectric element is displaced toward a pressure chamber to be pressurized. SOLUTION: A voltage of 80 V is applied to a pressure chamber displacement part 11, is expanded sharply, and lifts a dry film 7 by about 160 nm in the arrow 32 direction to decrease the volume of a pressure chamber 4. Simultaneously, a partition displacement part 13 pulls a pressure chamber partition 14 by about 20 nm in the arrow 31, 33 directions, so that the pressure of the piezoelectric body of the pressure displacement part 11 is applied effectively to the pressure chamber 4 to reduce the pressure loss of the pressure chamber displacement part 11. Moreover, a cross stroke (the reduction of velocity and quantity of ink particles) due to the recess of a channel plate, which is generated when many nozzles are driven simultaneously, can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet printer, and more particularly to an ink jet printer head using a piezoelectric material.

[0002]

2. Description of the Related Art Desktop type printers include:
Several systems such as an ink jet system and a thermal transfer system have been put to practical use. Among these various methods, the ink jet method has a simple structure and is easy to colorize.
In addition, since it has features such as low noise, it is expected as a mainstream of a recording system in the future.

The present applicant has previously proposed a technique relating to a direct drive type ink jet printer in which a piezoelectric body itself forms a part of a pressure chamber among ink jet printers. This direct drive system has the features that the number of parts is small, the structure is simple, and the cost can be reduced.

FIG. 6 shows the structure of such a direct drive type ink jet printer head. In addition, FIG.
FIG. 4 is a perspective view of a pressure chamber 4 and the like, excluding a nozzle plate on a front surface. A passage through which ink flows is provided inside the flow path plate 2 in FIG. 6A, and a plurality of pressure chambers 4 for applying pressure to the ink are provided on the front surface of the flow path plate 2 and separated by a pressure chamber partition 14. Then, the flow path plate 2 is pressure-bonded to the piezoelectric block 1 via the dry film 7 to form an ink jet printer head.

A plurality of electrodes 9 are stacked inside the piezoelectric block 1 below the pressure chamber 4. The stacked electrodes 9 are connected alternately at the front part and the rear part of the piezoelectric block 1, and the electrode terminals are drawn out. One of them is drawn out to the front part of the piezoelectric block 1 and serves as a front electrode terminal 51.

FIG. 6B is a sectional view of the direct drive type ink jet printer head of FIG. 6A cut away in the depth direction of the pressure chamber 4. Inside the flow path plate 2, a pressure chamber 4 for applying pressure to ink, an ink supply path 5 for supplying ink to the pressure chamber 4, and an ink common path 6 as an ink reservoir
Are formed. The electrodes 9 connected alternately inside the piezoelectric block 1 are drawn out as front electrode terminals 51 at the front of the piezoelectric block 1 and as rear electrode terminals 52 at the rear of the piezoelectric block 1. I have. Also,
A nozzle 8 for ejecting ink is formed on the front nozzle plate 3.

In this state, when a predetermined voltage is applied between the front electrode terminal 51 and the rear electrode terminal 52, the piezoelectric body in the region where the voltage is applied is displaced. At this time, if the pressure chamber 4 is displaced in a direction of increasing the volume, the pressure chamber 4 sucks ink from the ink common path 6, and if the pressure chamber 4 is displaced in a direction of reducing the volume of the pressure chamber 4, the ink flows from the nozzle 8. Inject.

FIG. 7 is an exploded perspective view of such a direct drive type ink jet printer head. FIG. 7 (1)
FIG. 4 is a perspective view of the flow path plate 2, showing a state viewed from below to show an internal structure. The flow path plate 2 is formed by etching and dicing photosensitive glass, and further includes a pressure chamber 4, an ink supply path 5, and an ink common path 6.

FIG. 7B is a perspective view showing the internal structure of the piezoelectric block 1. The piezoelectric block 1 includes a flow path plate 2
An electrode 9 is formed by screen printing on a portion corresponding to the pressure chamber 4 and is pressure-bonded via the flow path plate 2 and the dry film 7. FIG. 7C is a perspective view illustrating the nozzle plate 3. The nozzle plate 3 is provided with a nozzle 8 at a position corresponding to the pressure chamber 4 of the flow path plate 2.

FIG. 7D is a perspective view showing the assembled direct drive type ink jet printer head. The flow path plate 2 and the piezoelectric block 1 are joined via a dry film 7, and the nozzle plate 3 is bonded by aligning the nozzle 8 with the pressure chamber 4. However, FIG. 7D shows the nozzle plate 3 in a see-through state.

[0011]

In FIG. 6, when a voltage is applied between the front electrode terminal 51 and the rear electrode terminal 52 of the piezoelectric block 1 to displace the driving portion provided with the electrodes 9, the piezoelectric block 1 A portion where no electrode is provided below the pressure chamber partition 14 inside the body block 1 (non-drive portion)
Is also displaced by being pulled by the driving portion. For example, if the driving part is displaced by 165 nm, the non-driving part will be about 14 nm.
Displaced to the extent. This displacement pushes the pressure chamber partition 14 through the dry film 7. For this reason, the pressure of the driving portion to be applied to the pressure chamber 4 is transmitted to the pressure chamber partition 14, and a pressure loss in the pressure chamber 4 occurs.

As the number of driving pressure elements increases, the displacement of the non-driving portion increases. For example, all pins of the 32-pin piezoelectric block 1 are driven, and the driving portion is 165 nm.
When displaced, the non-driven part displaces about 38 nm.
For this reason, a plurality of pressure chamber partition walls 1
4 to displace the entire flow path plate 2 upward in the state of FIG. 7 (4). The displacement of the entire flow path plate 2 reduces the efficiency of reducing the volume of the pressure chamber 4, resulting in pressure loss and crosstalk in the pressure chamber 4, and reduces the particle speed and amount of ink ejected from the nozzle 8. The crosstalk is a rate at which, when a plurality of piezoelectric elements are simultaneously driven, the amount of ink ejected from one of the nozzles is lower than the amount of ink ejected when the piezoelectric element is driven alone. Say.

In order to reduce pressure loss and crosstalk in the pressure chamber 4, in Japanese Patent Application Laid-Open No. 6-143562, adjacent piezoelectric elements are driven in the opposite direction in the case of single driving. Simultaneous driving becomes difficult, and the printing speed of the printer is reduced. In addition, when an adjacent piezoelectric element that is not a driving target is driven, mutual interference occurs fluidly, and the ink ejection amount becomes non-uniform, thereby deteriorating print quality.

Accordingly, the present invention is directed to a direct drive type ink jet system which reduces pressure loss in a pressure chamber and crosstalk when a plurality of piezoelectric elements are driven simultaneously, and prevents a decrease in the particle speed and the amount of ejected ink. It is an object to provide a printer head.

[0015]

SUMMARY OF THE INVENTION An object of the present invention is to provide an ink jet printer head having a first piezoelectric element formed adjacent to a bottom surface of a pressure chamber and pressurizing the pressure chamber. A second piezoelectric element formed on both sides adjacent to a side surface of the pressurizing chamber, wherein the first piezoelectric element is displaced in the direction of the pressure chamber and pressurized; Is achieved by providing an ink jet printer head characterized in that it is controlled to be displaced in a direction opposite to the first piezoelectric element.

According to the present invention, when the first piezoelectric element is displaced in the direction of the pressure chamber and pressurizes, the second piezoelectric element is displaced in the opposite direction to the first piezoelectric element. Pull the sides. For this reason, the loss of pressure to be applied to the pressure chamber is reduced, and crosstalk when a plurality of piezoelectric elements are driven simultaneously can be reduced. Further, it is possible to prevent a decrease in the particle speed and the amount of the ejected ink.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, such embodiments do not limit the technical scope of the present invention.

FIG. 1 is a schematic sectional view showing the structure of an ink jet printer head according to a first embodiment of the present invention. The flow path plate 2 is formed by etching and dicing photosensitive glass, and further includes a pressure chamber 4 and a pressure chamber partition 14 for applying pressure to the ink.

In the piezoelectric block 1, a pressure chamber displacement portion 11 is formed by screen-printing the pattern of the electrode 9 on a portion located below the pressure chamber 4. The pattern of the electrode 15 is also screen-printed on a portion located below the pressure chamber partition 14 to form the partition displacement portion 13. Then, the whole is fired to form the piezoelectric block 1.

The electrodes 9 of the stacked pressure chamber displacement unit 11 are
Every other is connected in the vertical direction, pulled out as a front electrode terminal 51 on the front surface of the piezoelectric block 1, and
It is drawn out as a rear electrode terminal (not shown). Similarly to the electrodes of the pressure chamber displacement unit 11, the electrodes 15 of the laminated partition displacement unit 13 are also connected alternately in the vertical direction, and are pulled out as front electrode terminals 20 on the front surface of the piezoelectric block 1 and on the rear surface. Then, it is pulled out as a rear electrode terminal (not shown).

Here, the pressure chamber displacement section 11 and the partition wall displacement section 1
The three electrodes 9 and 15 are separated, and the pressure chamber displacement unit 11 and the partition wall displacement unit 13 can be individually controlled by individually applying a voltage to each of the electrode terminals 51 and 20 and the like. Further, in the present embodiment, a slit 10 is provided between the pressure chamber displacement unit 11 and the partition wall displacement unit 13 in order to further improve individual control characteristics.

Then, the flow path plate 2 and the piezoelectric block 1 are pressure-bonded via a dry film 7, and the nozzles of the nozzle plate are aligned with and bonded to the pressure chambers 4 as shown in FIGS.
Let it be an inkjet printer head.

FIG. 2 shows a waveform of a voltage applied to the ink jet printer head according to the first embodiment of the present invention, and FIG. 3 is an explanatory diagram of the operation at that time. FIG.
FIG. 2A shows a voltage waveform applied to the piezoelectric body of the pressure chamber displacement unit 11, and FIG. 2B shows a voltage waveform applied to the piezoelectric body of the partition wall displacement unit 13.

As shown in FIGS. 2A and 2B, the time t
In the normal state (non-printing state) of No. 1, the pressure chamber displacement portion 1
A DC voltage of 80 V is applied to one piezoelectric body, and a DC voltage of 10 V is applied to the piezoelectric body of the partition wall displacement portion 13.

FIG. 3A shows a state of each displacement portion in a normal state. Since a voltage of 80 V is applied to the pressure chamber displacement unit 11, the pressure chamber displacement unit 11 is displaced in a direction in which the pressure chamber 4 is pressurized via the dry film 7. In addition, since a voltage of 10 V is also applied to the piezoelectric body of the partition displacement portion 13, the pressure chamber partition 14 is pressed with a pressure corresponding to the voltage.

Next, a printing period shown at times t2 and t3 is entered. First, the voltage applied to the piezoelectric body of the pressure chamber displacement section 11 is changed from 80 V to 0 V in a time of 100 μs indicated by time t2.
The pressure chamber displacing portion 11 is displaced downward by about 160 nm to increase the volume in the pressure chamber 4 and suck ink. On the other hand, the piezoelectric body of the partition wall displacement portion 13 is
The voltage of 10 V is kept applied even when the piezoelectric body of the pressure chamber displacement unit 11 starts to suck ink.

FIG. 3B shows a state at the time of ink suction (time t2).
The state of is shown. Since the voltage applied to the piezoelectric body of the pressure chamber displacement unit 11 decreases, the pressure chamber displacement unit 11
Dry film 7 which is displaced by m and forms a part of the pressure chamber 4
In the direction of arrow 30 to increase the volume of the pressure chamber 4. On the other hand, the voltage of 10 V is still applied to the partition wall displacement portion 13, and the displacement does not change.

Next, the voltage applied to the piezoelectric body of the pressure chamber displacement unit 11 is rapidly increased to 80 V in 5 μs shown at time t3, and the pressure chamber displacement unit 11 is raised upward by about 160 nm.
The ink is ejected from the nozzle 8 by displacing and pushing out the ink in the pressure chamber 4. At the same time,
At a time of 5 μs indicated by time t3, the voltage applied to the partition wall displacement portions 13 on both sides of the pressure chamber displacement portion 11 is suddenly dropped to 0 V, and the partition wall displacement portions 13 are displaced downward by about 20 nm, so that the dry film 7 , The pressure chamber partition wall 14 is pulled.

FIG. 3 (3) shows the time of ink ejection (time t3).
The state of is shown. The pressure chamber displacement unit 11 is applied with a voltage of 80 V, rapidly expands, and causes the dry film 7 to move about 160 nm.
Pushing up in the direction of arrow 32 reduces the volume of pressure chamber 4. At the same time, the partition wall displacement part 13 is
Is pulled in the direction of arrows 31 and 33 by about 20 nm.

Therefore, the pressure of the piezoelectric body in the pressure chamber displacement section 11 is effectively applied to the pressure chamber 4, and the pressure loss in the pressure chamber displacement section 11 is reduced. Further, it is possible to reduce crosstalk (reduction in ink particle speed and particle amount) due to escape of the flow path plate 2 generated during simultaneous driving of multiple nozzles.

After the ink ejection, the voltage applied to the piezoelectric body of the pressure chamber displacement section 11 remains at 80 V, and the voltage applied to the partition wall displacement section 13 changes from 0 V to 10 V in 20 μs indicated by time t4. It increases at a constant gradient, and maintains a voltage of 10 V after time t5. Then, after time t5, a normal state (non-printing state) is set. This operation is performed at 7.2 kHz.
By repeatedly performing z, characters and pictures are printed.

FIG. 4 is a schematic sectional view showing the structure of an ink jet printer head according to a second embodiment of the present invention. In the present embodiment, the piezoelectric body of the pressure chamber displacement unit 11 is laminated by the green sheet method, and at the same time, the piezoelectric body is also laminated on the portion located below the pressure chamber partition 14 to form the partition displacement unit 13. Thereafter, the resultant is integrally fired to obtain the piezoelectric block 1. As in the first embodiment, the piezoelectric body of the pressure chamber displacement unit 11 and the piezoelectric body of the partition wall displacement unit 13 can be individually controlled by applying voltages to electrode terminals (not shown).

The flow path plate 2 in which the pressure chambers 4 and the like are formed by etching and dicing is used as a dry film 7.
The first embodiment is the same as the first embodiment in that the nozzle plate is pressure-bonded, and then the nozzle plate is positioned and bonded to the pressure chamber to form a head segment.

In the second embodiment, a piezoelectric block 1 is formed by forming a laminated piezoelectric body by a green sheet method.
This has the advantage that the manufacturing process can be simplified and the cost can be reduced, and the desired displacement characteristics can be obtained at a low voltage by using a laminated piezoelectric body. If this laminated piezoelectric body is used, a displacement of 165 nm similar to that of the first embodiment can be realized with an applied voltage of 33 V. Therefore, sufficient displacement can be ensured even if the number of stacked piezoelectric bodies of the pressure chamber displacement portion 11 and the partition displacement portion 13 is small.

FIG. 5 is a schematic sectional view showing the structure of an ink jet printer head according to a third embodiment of the present invention. In the present embodiment, the pressure chamber displacement portion 11 and the partition wall displacement portion 13 are formed by integral solid electrodes by screen printing and fired to obtain the piezoelectric block 1.

Thereafter, a slit 10 is formed by using a dicing saw to divide the pressure chamber displacement section 11 and the partition wall displacement section 13. As in the first embodiment, the pressure chamber displacement unit 11
The piezoelectric body and the piezoelectric body of the partition displacement part 13 can be individually controlled by applying a voltage to each of the electrode terminals (not shown).

The flow path plate 2 in which the pressure chambers 4 and the like are formed by etching and dicing is used as a dry film 7.
The first embodiment is the same as the first embodiment in that the nozzle plate is pressure-bonded, and then the nozzle plate is positioned and bonded to the pressure chamber to form a head segment.

In the third embodiment, a slit is not formed between electrode patterns, but an integral solid electrode is divided by the slit. Therefore, a margin for displacement of the solid electrode is widened, and processing is relatively easy. Easy. When printing the electrode pattern, the pressure chamber displacement unit 11 and the partition wall displacement unit 13 are used.
There is an advantage that the process is easy because it can be integrally formed without distinction.

[0039]

As described above, according to the present invention, the pressure loss to the pressure chamber and the crosstalk when a plurality of piezoelectric elements are driven at the same time are reduced, and the particle speed and amount of the ejected ink are reduced. It is possible to provide a direct drive type ink jet printer head which can prevent the occurrence of the problem.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing a structure of an ink jet printer head according to a first embodiment of the present invention.

FIG. 2 is an applied voltage waveform according to the first embodiment of the present invention.

FIG. 3 is an operation explanatory diagram of the first embodiment of the present invention.

FIG. 4 is a schematic sectional view illustrating a structure of an ink jet printer head according to a second embodiment of the present invention.

FIG. 5 is a schematic sectional view showing a structure of an ink jet printer head according to a third embodiment of the present invention.

FIG. 6 is an explanatory view showing the structure of a conventional ink jet printer head.

FIG. 7 is an exploded perspective view of a conventional ink jet printer head.

[Description of Signs] 1 Piezoelectric block 2 Channel plate 4 Pressure chamber 9 Pressure chamber displacement part electrode 10 Slit 11 Pressure chamber displacement part 13 Partition displacement part 14 Pressure chamber partition 15 Partition displacement part electrode

Claims (1)

[Claims] 1. An ink jet printer head having a first piezoelectric element formed adjacent to a bottom surface of a pressure chamber and pressurizing the pressure chamber, wherein both sides of the first piezoelectric element are on side surfaces of the pressure chamber. A second piezoelectric element formed adjacent to the first piezoelectric element, wherein when the first piezoelectric element is displaced in the direction of the pressure chamber and pressurized, the second piezoelectric element is connected to the first piezoelectric element; An ink jet printer head controlled to be displaced in the opposite direction.