JP2001246744A - Piezoelectric type ink-jet printer head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent an electric short circuit between side face electrodes 28 by a simple structure when the side face electrodes 28 led out from driving electrodes 24 are formed to a side face of a piezoelectric actuator 20 in a piezoe lectric type ink-jet printer head in which a metallic cavity plate 10 with a pressure chamber 16 set for each nozzle 15 and the piezoelectric actuator of a plate form with the driving electrode 24 formed for each pressure chamber 16 are stacked with each other. SOLUTION: Recessed parts such as blanking holes 41, etc. are provided to a face of the cavity plate 10 where the piezoelectric actuator touches, thereby preventing each of the side face electrodes 28 from touching the cavity plate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

BACKGROUND OF THE INVENTION U.S. Pat.
No. 2,159 discloses a plurality of nozzles and a cavity plate having a pressure chamber for each nozzle, a driving electrode formed for each of the pressure chambers, and a common electrode common to adjacent pressure chambers. It consists of a plate-type piezoelectric actuator formed in a laminated manner with a piezoelectric sheet interposed,
This piezoelectric actuator proposes a piezoelectric ink jet printer head which is laminated on the cavity plate so that each pressure chamber in the cavity plate is closed by the piezoelectric actuator.

Further, in this prior art piezoelectric ink jet printer head, US Pat.
159 in the specification. As described in 15, a side electrode that is electrically connected to at least each of the drive electrodes is provided on a side surface orthogonal to the lamination surface of the piezoelectric actuator, and each of the drive electrodes is connected to each other through the side electrode. It is configured to connect to the outside.

[0004]

However, as described above,
Providing a side electrode for connection to each drive electrode to the outside on the side surface orthogonal to the lamination surface of the plate type piezoelectric actuator, the piezoelectric actuator is provided to the cavity plate so as to close each pressure chamber. When stacked, each side electrode provided on the side of this piezoelectric actuator comes into contact with or is likely to come into contact with the cavity plate. When the cavity plate is made of metal, the This causes an electrical short.

Therefore, in the prior art, the cavity plate is made of a non-conductive material such as alumina ceramic having electrical insulation, or an insulating sheet is provided between the cavity plate and the piezoelectric actuator. , The occurrence of an electrical short between the side electrodes is prevented.

However, when the cavity plate is made of a non-conductive material such as alumina ceramic as in the former case, the cavity plate becomes large in size to maintain a predetermined strength. In addition to this, there is a problem that material costs and processing steps are increased, and as a result, prices are considerably increased.

[0007] In addition, by sandwiching an insulating sheet between the cavity plate and the piezoelectric actuator as in the latter case, the cavity plate can be made of metal, and the size and cost can be reduced compared to the former. it can. However, on the other hand, the number of parts increases by the amount of sandwiching the insulating sheet,
For this reason, size reduction and cost reduction cannot be sufficiently achieved. In addition, there is a problem that the number of locations where ink leakage occurs increases.

An object of the present invention is to solve such a problem.

[0009]

In order to achieve the technical object, the present invention provides a cavity plate having a plurality of nozzles and a pressure chamber for each of the nozzles, and a cavity plate formed for each of the pressure chambers. And a plate-type piezoelectric actuator formed by laminating a piezoelectric sheet with a driving electrode and a common electrode common to adjacent pressure chambers, and the piezoelectric actuator is provided in the cavity plate, and in each of the cavity plates. A piezoelectric ink-jet printer that is stacked so as to close the pressure chamber with the piezoelectric actuator, and has a side electrode that is electrically connected to at least each of the drive electrodes on a side surface that is orthogonal to the stacking surface of the piezoelectric actuator. In the head, the surface of the cavity plate with which the piezoelectric actuator contacts Recesses for the non-contact is provided to each side electrodes in electrostatic actuators relative to the cavity plate. "It is characterized.

[0010]

In this configuration, when the piezoelectric actuator is stacked on the cavity plate,
The contact between the side electrodes on the side surface of the piezoelectric actuator and the cavity plate can be reliably prevented by the recess without interposing an insulating sheet therebetween.

Therefore, according to the present invention, since the cavity plate can be made of metal without using an insulating sheet, further reduction in size and cost can be achieved.
This has the effect that it can be reliably achieved without increasing the number of ink leakage points.

According to a second aspect of the present invention, a surface electrode which is electrically connected to each of the side electrodes is provided on a laminated surface of the piezoelectric actuator opposite to a laminated surface with which the cavity plate contacts. ing.

With this arrangement, the flexible flat cable for connection to an external device is overlapped and pressed against the laminated surface of the piezoelectric actuator opposite to the laminated surface with which the cavity plate is in contact. Can be securely connected to the surface electrodes with a simple structure.

In particular, since the recess has a long form extending along the side surface of the piezoelectric actuator, a plurality of side electrodes can be insulated by one recess. The cost can be reduced as compared with the case where the recess is provided for each side electrode.

[0015]

Embodiments of the present invention will be described below with reference to the drawings.

1 to 7 show a first embodiment.

In this figure, reference numeral 10 denotes a cavity plate made of a metal plate, reference numeral 20 denotes a plate-type piezoelectric actuator laminated on the cavity plate 10, and reference numeral 30 denotes an external device. 2 shows flexible flat cables which are overlap-joined to the piezoelectric actuator 20 for connection to the piezoelectric actuator.

The cavity plate 10 is configured as shown in FIGS.

That is, it has a structure in which four thin metal plates of a nozzle plate 11, two manifold plates 12, a spacer plate 13 and a base plate 14 are laminated.

The nozzle plate 11 is provided with nozzles 15 for ejecting ink having a small diameter along a longitudinal center line 11a of the nozzle plate 11 at a fine pitch P.
Many are drilled at intervals of. In the two manifold plates 12, ink passages 12a are formed so as to extend along both sides of the row of the nozzles 15, and the ink passages 12a are formed in the nozzle plate 11 and the nozzle plate 11 for the two manifold plates 12. The structure is sealed by the lamination of the spacer plates 13.

The base plate 14 is provided with a plurality of narrow pressure chambers 16 extending in a direction perpendicular to the longitudinal center line 14a. Each of these pressure chambers 1
Numerals 6 are alternately provided such that their tips 16a are located on the longitudinal center line 14a and alternately extend in the opposite direction from the longitudinal center line 14a. The tip 16a of each pressure chamber 16
Is provided on the nozzle 15 of the nozzle plate 11 with the spacer plate 13 and the two manifold plates 1.
2, while the other end 16b of each of the pressure chambers 16 is connected to a corresponding one of the pressure chambers 16 through a through hole 18 formed in the spacer plate 13. Ink passage 12 in manifold plate 12
a.

Thus, supply holes 19 formed at one end of the spacer plate 13 and the base plate 14 are formed.
a and 19b are distributed into the pressure chambers 16 from the ink passages 12a through the through holes 18, and then from the pressure chambers 16 to the ink holes 12a. 17 through the pressure chamber 16
Is reached.

Each of the pressure chambers 16 has another end 1.
6b is provided with a flow restricting throttle portion 16c whose thickness is partially reduced in a portion adjacent to 6b, and a connecting piece 16 whose thickness is partially reduced for reinforcement at a substantially central portion thereof.
d is provided integrally.

On the other hand, the piezoelectric actuator 20 is
As shown in FIG. 3, the three piezoelectric sheets 21, 22, and 23 are stacked, and the uppermost piezoelectric sheet 21 of the piezoelectric sheets 21, 22, and 23 is provided on the upper surface of the cavity plate 10. The drive electrode 24 having a narrow width is provided at each location of the pressure chamber 16, and one end 24 a of the drive electrode 24 is provided at both of the laminated surfaces 20 a and 2
It is formed so as to be exposed on both left and right side surfaces 20c orthogonal to 0b.

On the upper surface of the next stage piezoelectric sheet 22, a common electrode 25 common to a plurality of pressure chambers 16 is provided.
However, a portion 25 a of the common electrode 25 is formed so as to be exposed on both left and right side surfaces 20 c of the piezoelectric actuator 20.

On the upper surface of the uppermost piezoelectric sheet 23,
A surface electrode 26 for each of the drive electrodes 24 and a surface electrode 27 for the common electrode 25 are provided so as to be aligned along both left and right side surfaces 20 c of the piezoelectric actuator 20.

Reference numerals 24 'and 25' indicate discarded pattern electrodes.

The left and right side surfaces 20 orthogonal to the upper and lower laminated surfaces 20a and 20b of the piezoelectric actuator 20 are also provided.
c, a side electrode 28 for electrically connecting each drive electrode 24 and its surface electrode 26 is formed, and in addition, the common electrode 25 and the surface electrode 27 are electrically connected. Side electrode 29 is formed.

In the illustrated embodiment, a piezoelectric sheet 21 provided with a drive electrode 24 is used as the piezoelectric actuator 20.
And the piezoelectric sheet 22 provided with the common electrode 25 as one pair, and this is a case where only one pair is laminated. However, the present invention is not limited to this, and the piezoelectric sheet 21 provided with the drive electrode 24 may be Alternatively, a plurality of pairs including the piezoelectric sheet 22 provided with the common electrode 25 may be stacked.

The plate-type piezoelectric actuator 20 having such a configuration is provided with the cavity plate 10.
On the other hand, the piezoelectric actuators 20 are laminated so that the pressure chambers 16 in the cavity plate 10 are closed by the lower laminated surface 20b of the piezoelectric actuator 20. Further, on the upper laminated surface 20a of the piezoelectric actuator 20,
When the flexible flat cable 30 is overlapped and pressed, the flexible flat cable 30
Are electrically connected to the surface electrodes 26 and 27, respectively.

In this configuration, any one of the driving electrodes 24 in the piezoelectric actuator 20 is selected.
And a common electrode 25, a voltage is applied between the piezoelectric sheet 21 and the drive electrode 24 to which the voltage is applied. By reducing the internal volume of the pressure chamber 16 corresponding to the drive electrode 24, the pressure chamber 16
The ink inside is ejected from the nozzle 15 in the form of droplets, and predetermined printing is performed.

By the way, the piezoelectric actuator 20 is
When the piezoelectric actuator 20 is stacked on the cavity plate 10 such that the lower stacking surface 20b of the piezoelectric actuator 20 closes each pressure chamber 16 in the cavity plate 10, the side surface 2 of the piezoelectric actuator 20 is
Each of the side electrodes 28 and 29 formed at 0c is in contact with or more likely to contact the metal cavity plate 10, and the respective side electrodes 28 and 29 are increased.
An electrical short occurs between each other.

Therefore, side electrodes 28 and 29 are provided on the base plate 14 of the metal cavity plate 10 at portions corresponding to the left and right side surfaces 20c of the piezoelectric actuator 20, respectively.
Punching holes 41 and 42, which are one embodiment of the recess that is not in contact with 0, are formed so as to extend along the side surface 20c.

By piercing the punched holes 41 and 42,
Since the side electrodes 28 and 29 on the left and right side surfaces 20c of the piezoelectric actuator 20 can be prevented from contacting the cavity plate 10, the side electrodes 2
It is possible to reliably prevent an electric short circuit from occurring between 8, 8 and 29.

In this case, the punched holes 41,
42 may be provided for each of the side electrodes 28 and 29. However, as shown in the figure, a long groove extending along the side surface 20c may be used to form the side electrodes 28 and 29.
The cost can be reduced as compared with the case where the unit is provided for every nine locations. Further, as described above, the recess for making the side electrodes 28 and 29 non-contact with the cavity plate 10 is formed in the punched hole 4 formed in the base plate 14.
1, 42, by providing the recess,
It can be easily done by stamping and pressing.

Next, FIG. 8 shows a second embodiment.

In the second embodiment, as described above, the recesses for making the side electrodes 28 and 29 out of contact with the cavity plate 10 are used as the recesses 41 and
42 instead of the cavity plate 1
0, the concave groove 4 formed in the base plate 14
3

The recessed groove 43 is formed in each of the side electrodes 28 and 29.
In this case, or by extending the piezoelectric actuator 20 along the side surface 20c of the piezoelectric actuator 20, it is possible to reliably prevent an electric short circuit between the side electrodes 28 and 29 as described above. . In addition, the concave groove 4
By setting 3, it is possible to avoid a decrease in strength as compared with the case where the punched hole is formed.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view showing a first embodiment of the present invention.

FIG. 2 is a perspective view showing one end of a cavity plate and a piezoelectric actuator in FIG. 1;

FIG. 3 is an enlarged sectional view taken along line III-III of FIG. 2;

FIG. 4 is an enlarged sectional view showing a state in which a cavity plate and a piezoelectric actuator are stacked in FIG. 3;

FIG. 5 is an exploded perspective view of the cavity plate.

FIG. 6 is a partially enlarged perspective view of the cavity plate.

FIG. 7 is an exploded perspective view of the piezoelectric actuator.

FIG. 8 is a partially enlarged perspective view showing a second embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 Cavity plate 11 Nozzle plate 12 Manifold plate 13 Spacer plate 14 Base plate 15 Nozzle 16 Pressure chamber 20 Piezoelectric actuator 21, 22, 23 Piezoelectric sheet 24 Drive electrode 25 Common electrode 26, 27 Surface electrode 28, 29 Side electrode 30 Flexible flat cable 41, 42 punched hole 43 concave groove

Claims (4)

[Claims] A piezoelectric sheet is formed by a plurality of nozzles, a cavity plate having pressure chambers for each nozzle, a driving electrode formed for each pressure chamber, and a common electrode common to adjacent pressure chambers. It is composed of a plate-type piezoelectric actuator formed so as to be sandwiched therebetween, and the piezoelectric actuator is laminated on the cavity plate so as to close each pressure chamber in the cavity plate with the piezoelectric actuator, and In a piezoelectric inkjet printer head in which at least a side electrode that is electrically connected to each of the drive electrodes is provided on a side surface orthogonal to a lamination surface of the piezoelectric actuator, a surface of the cavity plate that contacts the piezoelectric actuator is provided. The side electrodes of the piezoelectric actuator are each provided with a cavity plate. A piezoelectric ink jet printer head, wherein a concave portion is provided to make contact with the piezoelectric ink jet printer. 2. The piezoelectric actuator according to claim 1, wherein a surface electrode which is electrically connected to each of said side electrodes is provided on a laminated surface of said piezoelectric actuator opposite to a laminated surface with which a cavity plate contacts. A piezoelectric ink jet printer head characterized in that: 3. A piezoelectric ink jet printer head according to claim 1, wherein said recess has a long form extending along a side surface of the piezoelectric actuator. 4. A piezoelectric ink jet printer head according to claim 1, wherein said recess is in the form of a punched hole or a recessed groove.