JPH11115181A - Ink jet printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink jet printer which is characterized by arranging pressure chambers highly densely and is almost free from a crosstalk. SOLUTION: This ink jet printer comrpises a pressure chamber plate with plural pressure chambers separated from each other by a partition wall, a piezoelectric member 14 with a drive part 22 for injecting an ink which is arranged opposite to the pressure chambers and a partition wall supporting part 24 arranged opposite to the partition wall, a vibrating plate arranged between the pressure chamber plate and the piezoelectric member 14 and a control means 50 for activating the drive part 22 and the partition wall supporting part 24.

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 that ejects ink by a piezoelectric element.

[0002]

2. Description of the Related Art Ink jet printers that eject ink by piezoelectric elements are widely used in copiers, facsimile machines, computers, word processors, and composite devices thereof. 12 and 13 are views showing an example of a conventional ink jet printer. 12 and 13, the ink jet printer 1 includes a pressure chamber plate 2, a piezoelectric member 3, and a vibration plate 4 disposed between the pressure chamber plate 2 and the piezoelectric member 3.

The pressure chamber plate 2 has a plurality of pressure chambers 6 separated by partition walls 5. The piezoelectric member 3 includes a driving unit 7 for ejecting ink disposed opposite to the pressure chamber 6 and a partition supporting portion 8 disposed opposite to the partition 5.
Further, the inkjet printer 1 includes a nozzle plate having a nozzle communicating with the pressure chamber 6 of the pressure chamber plate 2.

When ink is ejected, a voltage is applied to the driving section 7 of the piezoelectric member 3, and the driving section 7 is extended toward the corresponding pressure chamber 6. The ink is ejected from the nozzle by applying pressure to the nozzle.

[0005]

The partition wall supporting portion 8 of the piezoelectric member 3 faces the partition wall 5 with the diaphragm 4 interposed therebetween.
Are supported on the piezoelectric member 3. Normally, the pressure chamber plate 2 is held in a fixed positional relationship with respect to the piezoelectric member 3 by the contact between the partition wall supporting portion 8 and the partition wall 5 via the vibration plate 4. Therefore, as shown in FIG. 12, when a voltage is applied to the drive unit 7 to eject ink (single pin ejection), a fixed amount of ink is ejected.

However, as shown in FIG. 13, when a voltage is applied to the drive unit 7 to eject ink, the pressure chamber plate 2 has a very small Displaced in the direction away from the member 3 (displacement Δ), the apparent volume of the pressure chamber 6 increases accordingly. As a result, the decrease in the volume of the pressure chamber 6 due to the application of the voltage to the drive unit 7 for ejecting ink is different from an expected value, and the print quality deteriorates and crosstalk occurs. This tendency is small when a voltage is applied to one drive unit 7 to eject ink (single pin drive) as shown in FIG. 12, but a voltage is applied to a plurality of drive units 7 simultaneously to eject ink ( It becomes larger when multiple pin injections are performed.

[0007] Accordingly, there is a difference in printing between the single-pin injection and the multiple-pin injection, and the printing quality is degraded. Further, in order to reduce the crosstalk, the pitch of the pressure chamber has to be increased. SUMMARY OF THE INVENTION It is an object of the present invention to provide an ink jet printer in which pressure chambers are arranged at a high density and crosstalk is reduced.

[0008]

An ink jet printer according to the present invention comprises a pressure chamber plate having a plurality of pressure chambers separated by partition walls, and a driving unit for ejecting ink disposed opposite to the pressure chambers. A piezoelectric member having a partition support portion disposed opposite to the partition, a diaphragm disposed between the pressure chamber plate and the piezoelectric member, and a drive unit and the partition support portion, respectively. And control means for moving.

In the above configuration, the partition wall supporting portion supporting the partition wall of the pressure chamber is formed so as to be movable by applying a voltage. The partition support portion does not necessarily need to be driven when the pressure chamber plate is displaced so as to be slightly apart from the piezoelectric member (during single-pin injection). However, when the pressure chamber plate is displaced so as to be separated from the piezoelectric member by a certain degree (at the time of ejecting a plurality of pins), the partition wall supporting portion prevents the pressure chamber plate from being separated from the piezoelectric member. Driven. In this way, even if the number of ejection pins (the number of driven units driven) changes, the volume of the pressure chamber is prevented from fluctuating, and the ink is discharged while changing the volume of the pressure chamber accurately according to the operation of the drive unit. By jetting, crosstalk can be prevented. As described above, the flying characteristics of the ink are stabilized, and high printing quality is achieved. Further, since it is not necessary to increase the pitch, the arrangement of the pressure chambers can be increased.

Preferably, the piezoelectric member has a groove extending in parallel, and the driving portion and the partition wall supporting portion are separated by the groove. In addition, an electrode provided on the driving unit, an electrode provided on the partition supporting portion, a conductive member connected to the electrode of the driving portion and the electrode on the partition supporting portion, and provided on one end surface of the piezoelectric member. And a membrane.

Preferably, the control means does not drive the partition supporting portion during single-pin injection, but drives the partition supporting portion in a contracting direction during multi-pin injection. Alternatively, the control means drives the partition support portion in the extending direction at the time of single-pin injection, and drives the partition support portion without driving or reducing the extension amount at the time of multiple-pin injection.

[0012]

1 and 2 show an ink jet printer according to an embodiment of the present invention. The ink jet printer 10 includes a pressure chamber plate 12 and a piezoelectric member 14.
And a diaphragm 16 disposed between the pressure chamber plate 12 and the piezoelectric member 14. The pressure chamber plate 12 has a plurality of pressure chambers 20 separated by partition walls 18. Piezoelectric member 1
Reference numeral 4 includes a driving unit 22 for ejecting ink disposed to face the pressure chamber 20 and a partition support portion 24 disposed to face the partition 18.

The piezoelectric member 14 has a groove 26 extending parallel to the surface thereof.
6 separated. Inkjet printer 1
0 comprises a nozzle plate 28 having nozzles 30. The nozzle plate 28 is bonded to the pressure chamber plate 12 such that the pressure chamber 20 communicates with the nozzle 30. Further, the pressure chamber plate 12 and the vibration plate 16, and the vibration plate 16 and the piezoelectric member 14
Are bonded to each other.

The piezoelectric member 14 is an integral block of a piezoelectric material in which a driving portion 22, a partition wall support portion 24, and a groove 26 are formed. As shown in FIGS. 2 to 4, electrodes are formed on the driving section 22 and the partition wall supporting section 24 of the piezoelectric member 14, respectively. The driving unit 22 includes the piezoelectric member 14
A plurality of layers of electrodes 32 extending from the front side (nozzle plate 28 side) to the rear side, and several layers of electrodes 34 extending from the rear side to the front side of the piezoelectric member 14. The electrodes 32 and the electrodes 34 alternately overlap inside the drive unit 22, and thus apply a voltage to the drive unit 22 in this overlapping portion, and thus drive the drive unit 22 toward or toward the pressure chamber 20. Can be driven away from the vehicle.

The partition support portion 24 includes several layers of electrodes 36 extending from the front side to the rear side of the piezoelectric member 14 and several layers of electrodes 38 extending from the rear side to the front side of the piezoelectric member 14. . The electrodes 36 and the electrodes 38 alternately overlap within the partition support portion 24, thus applying a voltage to the partition support portion 24 at this overlapping portion, thus moving the partition support portion 24 relative to the partition 18. Can be.

FIG. 5 shows a conductive film 40 formed on the front surface of the piezoelectric member 14.
2 and the electrode 36 of the partition wall support portion 24. FIG. 6 shows a conductive film 42 formed on the upper surface of the piezoelectric member 14.
The conductive film 42 is connected to the conductive film 40 on the front surface of the piezoelectric member 14. FIG. 6 shows a conductive film 44 formed on the rear surface of the piezoelectric member 14.
Is connected to the conductive film 42 on the upper surface. Therefore, the piezoelectric member 1
The electrode 32 of the driving unit 22 and the electrode 36 of the partition wall supporting portion 24 appearing on the front surface of the piezoelectric member 4 are connected to the negative terminal of the power supply on the rear surface side of the piezoelectric member 14 via the conductive films 40, 42, 44.

Further, as shown in FIG. 6, the electrodes 34 of the drive section 22 and the electrodes 38 of the partition wall supporting portion 24 which appear on the rear surface of the piezoelectric member 14 are individually connected to the positive terminal of the power supply by conductive films 46 and 48, respectively. Connected to. The conductive films 44, 46, and 48 are connected to the control device 5 including such a power supply.
Connected to 0. The control device 50 controls the current supplied to 46 and 48 to thereby control the driving unit 22 which is a piezoelectric element.
The driving unit 22 and the partition wall support portion 24 can be moved by controlling the voltage applied to the partition wall support portion 24.

When ink is ejected, the piezoelectric member 14
A voltage is applied to the selected driving unit 22 and the driving unit 2
2 is extended toward the corresponding pressure chamber 20, and the ink is ejected from the nozzle 30 by applying pressure to the ink in the pressure chamber 20 via the diaphragm 16. As described above, when a voltage is applied to the drive unit 22 to eject ink, the pressure chamber plate 12 is displaced in a direction away from the piezoelectric member 14 by a small amount due to the action of the pressure of the pressure chamber 20. However, the apparent volume of the pressure chamber 6 increases. As a result, the change in the volume of the pressure chamber 20 due to the application of the voltage to the drive unit 22 for ejecting the ink is smaller than an expected value, and the print quality deteriorates and crosstalk occurs.
A voltage is applied to the partition wall support portion 24 when such a problem may occur.

FIGS. 8 and 9 are diagrams showing an example of the application of a voltage to the partition wall support portion 24. FIG. FIG. 8 is a view showing a case where the pressure chamber plate 12 is displaced so as to be slightly apart from the piezoelectric member 14, for example, a case where a voltage is applied to one driving unit 22 (during single pin injection). In this case, the partition support portion 24 is not driven (no voltage is applied). FIG. 9 is a diagram illustrating a case where the pressure chamber plate 12 is displaced so as to be separated from the piezoelectric member 14 to some extent, for example, a case where a voltage is applied to the plurality of driving units 22 (during multi-pin injection). In this case, at least the partition wall support portion 24 near the driven portion 22 to be driven is driven in the contracting direction. This prevents the possibility of the displacement Δ shown in FIG. In this way, even if the number of injection pins (the number of driven driving units 22) changes, the pressure chamber 2
0 is prevented from fluctuating, and the ink can be ejected while the volume of the pressure chamber 20 is accurately changed according to the operation of the drive unit 22. Therefore, the flying characteristics of the ink are stable, and high printing quality is achieved. Further, since it is not necessary to increase the pitch, the arrangement of the pressure chambers 20 can be increased in density.

FIGS. 10 and 11 are diagrams showing another example of applying a voltage to the partition wall support portion 24. FIG. FIG. 10 shows that the partition wall supporting portion 24 is driven in the extending direction at the time of single pin injection. FIG. 11 shows that the partition wall support portion 24 is not driven during the injection of a plurality of pins. Alternatively, at this time, it is also possible to drive the partition support portion 24 so as to reduce the amount of extension. The partition support portion 24 is extended at the time of single pin injection,
By not driving the partition wall support portion 24 at the time of multiple pin injection, the partition wall support portion 24 is contracted as compared with the state where the partition wall support portion 24 is extended at the time of single pin injection, and so forth.

[0021]

As described above, according to the present invention,
Even if the number of ejection pins changes, the change in the volume inside the pressure chamber is kept constant, the flying characteristics of the ink are stabilized, and high printing quality can be achieved. Further, since it is not necessary to increase the pitch of the pressure chambers, the arrangement of the pressure chambers can be increased in density.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating an ink jet printer according to a first embodiment of the present invention.

FIG. 2 is an enlarged sectional view of a part of a pressure chamber plate and a piezoelectric member of FIG.

FIG. 3 is a cross-sectional view of the piezoelectric member taken along line III-III in FIG. 2;

FIG. 4 is a cross-sectional view of the piezoelectric member taken along line IV-IV in FIG.

FIG. 5 is a front view of the piezoelectric member shown in FIGS. 3 and 4;

FIG. 6 is a rear view of the piezoelectric member shown in FIGS. 3 and 4;

FIG. 7 is a plan view of the piezoelectric member shown in FIGS. 3 and 4;

FIG. 8 is a diagram illustrating an example of control of a partition supporting portion during single pin injection.

FIG. 9 is a diagram illustrating an example of control of a partition wall supporting portion at the time of jetting a plurality of pins with respect to the example of FIG. 8;

FIG. 10 is a diagram illustrating another example of control of the partition wall supporting portion during single pin injection.

11 is a diagram illustrating an example of control of a partition wall supporting portion at the time of jetting a plurality of pins with respect to the example of FIG. 10;

FIG. 12 is a diagram illustrating an example of control of a partition wall supporting portion at the time of single-pin ejection of a conventional inkjet printer.

FIG. 13 is a diagram illustrating an example of control of a partition wall supporting portion during injection of a plurality of pins with respect to the example of FIG. 12;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Inkjet printer 12 ... Pressure chamber plate 14 ... Piezoelectric member 16 ... Vibration plate 18 ... Partition wall 20 ... Pressure chamber 22 ... Drive part 24 ... Partition wall support part 26 ... Groove 28 ... Nozzle plate 30 ... Nozzle 32, 34, 36, 38 ... electrodes 40, 42, 44, 46, 48 ... conductive film 50 ... control device

Claims (5)

[Claims] 1. A pressure chamber plate having a plurality of pressure chambers separated by a partition, a driving unit for ejecting ink disposed opposite the pressure chamber, and a partition disposed opposite the partition. A piezoelectric member having a supporting portion, a diaphragm disposed between the pressure chamber plate and the piezoelectric member, and control means for moving the driving portion and the partition wall supporting portion. Characteristic inkjet printer. 2. The ink-jet printer according to claim 1, wherein the piezoelectric member has a groove extending in parallel, and the driving section and the partition wall supporting portion are separated by the groove. 3. An electrode provided on the drive section, an electrode provided on the partition support section, an electrode on the drive section and an electrode on the partition support section, provided on one end surface of the piezoelectric member. The inkjet printer according to claim 2, further comprising a conductive film provided. 4. The apparatus according to claim 1, wherein the control means does not drive the partition wall supporting portion during single-pin injection, but drives the partition wall supporting portion in a contracting direction during multi-pin injection. Inkjet printer. 5. The control means drives the partition wall supporting portion in a direction of extension in the case of single-pin injection, and drives the partition wall supporting portion not in driving or reduces the amount of extension in the case of multiple pin injection. The inkjet printer according to claim 1, wherein: