JPH1110876A - Ink jet recording head and manufacture of piezoelectric vibrator unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce cost by providing only two common electrodes to be formed on a piezoelectric vibrator. SOLUTION: At least a fixing face for a piezoelectric vibrator 9 on a fixed substrate 16 is to be conductive. A segment electrode 24 which is electrically independent from the adjacent piezoelectric vibrator 9 is formed on the tip face which is not stuck to the fixed substrate 16. A common electrode 26 is formed on the face which is not stuck to the fixed substrate 16 and is away from the segment electrode at a predetermined distance 25 and on the rear end face. A thickness of the end face of the common electrode 26a formed on the rear end face in opposition to the fixed substrate 16 is increased to form a conductive face 26b. The conductive face 26b and fixed substrate 16 are electrically connected with each other.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for sealing a pressure generating chamber on one side with a vibrating plate, and expanding and contracting the vibrating plate with a piezoelectric vibrator in a longitudinal vibration mode. The present invention relates to an ink jet recording head that generates ink droplets from ink.

[0002]

2. Description of the Related Art For example, when a piezoelectric vibrator in a longitudinal vibration mode as shown in Japanese Patent Application Laid-Open No. 5-104715 is used for driving an ink jet recording head, the contact area between the piezoelectric vibrator and the diaphragm is reduced. Since it can be made extremely small, a resolution of 180 DPI or more per unit can be realized.

As shown in FIG. 8, a piezoelectric vibrator A in a longitudinal vibration mode has an internal electrode B serving as one pole and an internal electrode C serving as the other pole laminated in a sandwich manner via a piezoelectric material D. One internal electrode B is exposed on the front end side, and the other internal electrode C is exposed on the rear end side, and is configured as having a piezoelectric constant d31 connected to the segment electrode E and the common electrode F at each end face, It is arranged and fixed at a fixed pitch on the fixed substrate G, and is configured to supply a signal from an external drive circuit by connecting the conductive pattern of the flexible cable H to the segment electrode E and the common electrode F. .

[0004]

Since the drive current of all the piezoelectric vibrators A flows through the common electrode F formed on the rear end side, the piezoelectric vibrators A are formed in order to reduce the resistance as much as possible. The conductive layers F1 to F3 are formed on the upper surface, the rear end surface, and the rear surface of A.
F3 is formed, and is divided into comb teeth so as to leave a part of the rear end side to secure a conductive path. In addition,
Reference numeral J in the figure denotes a flow path unit that receives ink pressurization by the piezoelectric vibrator A and discharges ink droplets. For this reason,
Electrode layers for external connection are required on the four surfaces of the front end surface, the rear end surface, and the front and back surfaces of the piezoelectric vibrator A, and these external electrode layers are intended to ensure corrosion resistance to ink and ease of soldering. Gold is used in. For this reason, if an attempt is made to form a thick electrode layer to reduce the resistance of the electrode layer to enable high-speed driving, there is a problem in that the formation of the electrode is costly. The present invention has been made in view of such a problem, and an object of the present invention is to provide an ink jet type that can reduce the use fee of expensive electrode materials by using three electrode layers for external connection. It is to provide a recording head.

[0005]

In order to solve such a problem, the present invention has a piezoelectric constant d31 obtained by alternately stacking internal electrodes of two poles extending in the displacement axis direction with a piezoelectric material interposed therebetween. The piezoelectric vibrator is fixed to the fixed substrate, and a drive signal is supplied to the piezoelectric vibrator by a flexible cable to expand the volume of the pressure generating chamber communicating with the nozzle opening.
In the ink jet recording head to be contracted, at least the fixed surface of the piezoelectric vibrator of the fixed substrate has conductivity, and the piezoelectric vibrator adjacent to the front end surface of the piezoelectric vibrator, the surface not bonded to the fixed substrate. A segment electrode that is electrically independent of the vibrator is formed on a rear end surface of the piezoelectric vibrator from a surface that is not adhered to the fixed substrate at a predetermined interval from the segment electrode, and faces the fixed substrate. The common electrode is formed such that the region to be contacted with the fixed substrate is formed thick enough to contact the fixed substrate, and the thickened region of the common electrode forms a conductive relationship with the fixed substrate.

[0006]

Since the thickened area at one end of the common electrode of the piezoelectric vibrator is connected in parallel to the conductive fixed substrate to reduce the electric resistance, the common electrode formed on the piezoelectric vibrator is formed on almost only two surfaces. Make it possible.

[0007]

1 and 2 show an embodiment of an ink jet recording head according to the present invention. A flow path unit 1 has a nozzle plate 3 in which nozzle openings 2 are formed at a constant pitch. A pressure generating chamber 4 communicating with the nozzle opening 2, a flow path forming substrate 7 provided with a reservoir 6 for supplying ink to the pressure generating chamber 4 through an ink supply port 5, and each piezoelectric vibration of the piezoelectric vibration unit 8 in the longitudinal vibration mode An elastic plate 10 that abuts on the tip of the child 9 and expands and reduces the volume of the pressure generating chamber 4 is integrally laminated.

The flow path unit 1 is connected to an opening surface 12 of a holder 11 formed by injection molding of a polymer material or the like, and the piezoelectric vibration unit 8 is connected to a flexible cable 13 for transmitting an external drive signal. The recording head is housed in the housing chamber 14, and the contact surface with each holder 11 is fixed by an adhesive, and a frame 15 also serving as a shield material is inserted into the nozzle plate side.

The piezoelectric vibrator 9 in the longitudinal vibration mode has an internal electrode 21 serving as one pole extending from the front end side to a position short of a fixed region with the fixed substrate 16 and an internal electrode 21 serving as the other pole extending from the vicinity of the front end to the rear end. The electrodes 22 are laminated in a sandwich manner with a piezoelectric material 23 interposed therebetween, and one of the internal electrodes 21 is exposed on the front end side and the other internal electrode 22 is exposed on the rear end side, so as to have a piezoelectric constant d31. I have.

One internal electrode 21 is provided on a segment electrode 24 having a conductive layer formed from the front end face to the vicinity of the center of the piezoelectric vibrator 9, and the other internal electrode 22 is provided on the center of the piezoelectric vibrator 9 from the rear end face. And is connected to a common electrode 26 having a conductive layer formed so as to have a certain distance 25 from the rear end side of the segment electrode 24.

On the other hand, the fixed substrate 16 is formed by forming a metal layer on the surface of a conductive material, for example, rustless steel or ceramics. The piezoelectric vibrator 9 is fixedly aligned and is conductively connected to a conductive surface 26b formed so as to extend from the rear end surface 26a of the common electrode 26 of the piezoelectric vibrator 9 to the fixed substrate 16 side.

At least one end of the row of the piezoelectric vibrators 9 has the same structure as that of the piezoelectric vibrator 9 as shown in FIGS. An internal electrode 21 which is one pole extending to the front
And an internal electrode 22 serving as the other pole extending from the vicinity of the front end to the rear end, are laminated in a sandwich shape via a piezoelectric material 23, and one internal electrode 21 is on the front end side and the other internal electrode 22 is on the rear end. The inner electrode 21 is further exposed to the segment electrode 24 having a conductive layer formed from the tip end face to the vicinity of the center of the piezoelectric vibrator 9, and the other internal electrode 22 is formed.
Is connected to a common electrode 26 having a conductive layer formed so as to have a fixed distance 25 from the rear end face to the center of the piezoelectric vibrator 9 and to the rear end side of the segment electrode 24. Also, a dummy piezoelectric vibrator 9 'formed slightly wider is fixed.

The segment electrode 24 and the common electrode 26 of each piezoelectric vibrator 9 of the vibrator unit 8 are connected to the conductive pattern of the flexible cable 13 via solder layers 28 and 29.

As shown in FIG. 5, the flexible cable 13 has a grounding conductive pattern 3 corresponding to the width of the dummy piezoelectric vibrators 9 ', 9' at both ends of the vibrator unit 8.
1, 31 and conductive patterns 32 for supplying drive signals corresponding to the segment electrodes 24 of the piezoelectric vibrators 9, 9, 9 #,
32, 32,... Are formed on the base material 33.

In this embodiment, when a drive signal is supplied from an external drive circuit via the flexible cable 13, the piezoelectric vibrator 9 for ejecting ink droplets passes through the conductive pattern 32 of the flexible cable 13 and the segment electrode 24. A drive signal is received by the internal electrode 21 serving as one pole, and the internal electrode 22 serving as the other pole via the conductive pattern for ground 31, the fixed substrate 16, and the common electrode 26, and the nozzle is displaced by the piezoelectric constant d31. Opening 2
To eject ink droplets.

As described above, in each of the piezoelectric vibrators 9, the common electrode 26 is connected in parallel to the fixed substrate 16 by the conductive surface 26b formed by increasing the thickness of the opposing surface of the fixed substrate 16. Therefore, the flexible cable 16 is connected to the ground conductive pattern 31 with a small resistance.

Next, a method of manufacturing the above-described piezoelectric vibrator unit 8 will be described with reference to FIGS. A conductive material 41 serving as an internal electrode serving as one pole extending from the front end to the terminal end side of the active region and a conductive material 42 serving as an internal electrode serving as the other pole extending from the rear end to the vicinity of the front end are sandwiched between piezoelectric materials 43. Piezoelectric vibrating plate 4 formed by laminating, drying and firing
4 and 44 are prepared (FIG. 6 (I)).

The piezoelectric vibrating plates 44, 44 are opposed to each other with two spacers 45, 45 therebetween so as to form an interval L such that the material for forming an external connection electrode can slightly wrap around during vapor deposition. The mask members 46, 46 are fixed to the exposed front and rear surfaces of the plates 44, 44 at the boundary regions between the segment electrodes and the common electrode (FIG. 6 (II)), and the external connection electrode forming material is applied to the entire periphery. The electrode layers 47 and 48 are formed by vapor deposition. In the course of this vapor deposition, the external connection electrode forming material slightly wraps around by the distance L between the two piezoelectric vibration plates 44, 44, and the flat surfaces 44a of the piezoelectric vibration plates 44, 44
Layers 47a and 48a slightly exposed from 44a are formed (FIG. 6 (III)).

When the two piezoelectric vibrating plates 44, 44 are separated and the mask members 46, 46 are removed at the stage when the vapor deposition is completed, the piezoelectric vibrating plates 44, 44 slightly protrude toward the front end surface, one surface, the rear end surface, and the opposing surface. Two piezoelectric vibrating plates 50, 50 having conductive layers 47, 48 formed substantially only on three surfaces can be obtained (FIG. 6 (IV)).

A region where only the other internal electrode 52 is formed, that is, an inactive region is positioned on a metal or a fixed substrate 53 having a conductive layer formed on a fixed surface (FIG. 7 (I)).
Layer 48 exposed from the end surface of piezoelectric vibrating plate 50 to the opposing surface
a is fixed with an adhesive so that a contacts the fixed substrate 53.

Then, slits 56, 56, 56,... Are formed from the tip on the free end side to at least the conductive layer 47 serving as a segment electrode and the rear end side of the conductive material 41 by a cutting tool 55 for dicing saw or wire saw. When the vibration region as the piezoelectric vibrator 9 and the region serving as the segment electrode are cut into a comb shape, the piezoelectric vibrator unit is completed.

When forming the slits 56, 56, 56,..., Both ends are cut out slightly wide to form slightly wide dummy piezoelectric vibrators 9 ', 9' which are not involved in vibration. Leaving 48 in a continuous state helps to reduce the electrical resistance of the common electrode.

[0023]

As described above, according to the present invention, at least the fixed surface of the piezoelectric vibrator of the fixed substrate has conductivity, and the distal end surface of the piezoelectric vibrator and the surface not adhered to the fixed substrate are provided. A segment electrode that is electrically independent of the adjacent piezoelectric vibrator is formed on the rear end face of the piezoelectric vibrator from a surface that is not adhered to the fixed substrate at a fixed distance from the segment electrode, and faces the fixed substrate. The common electrode is formed so that the area to be contacted with the fixed substrate is formed, and the thickened area of the common electrode forms a conductive relationship with the fixed substrate. In parallel, the electrical resistance can be reduced by connecting in parallel to the fixed substrate in the region, and the common electrode formed on the piezoelectric vibrator is reduced to the area for forming the external connection electrode by reducing the area for forming the external connection electrode substantially to only two. In That.

[Brief description of the drawings]

FIG. 1 is an assembled perspective view showing one embodiment of an ink jet recording head of the present invention.

FIG. 2 is a diagram showing a cross-sectional structure of the device.

FIG. 3 is a cross-sectional view showing a connection structure between a dummy piezoelectric vibrator of the recording head and a flexible cable.

FIGS. 4 (a) and 4 (b) are perspective views showing one embodiment of a piezoelectric vibration unit used for the recording head.

FIG. 5 is a diagram showing one embodiment of a flexible cable.

FIGS. 6 (I) to (IV) are diagrams showing an electrode forming step in the manufacturing steps of the vibrator unit used for the recording head, respectively.

FIGS. 7 (I) to (III) are diagrams showing the steps up to the division step in the manufacturing process of the vibrator unit used for the recording head.

FIG. 8 is a sectional view showing an example of a conventional ink jet recording head using a piezoelectric vibrator having a piezoelectric constant d31.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Flow path unit 8 Vibrator unit 9 Piezoelectric vibrator 9 'Dummy piezoelectric vibrator 13 Flexible cable 16 Fixed substrate 25 Segment electrode 26 Common electrode 26b Conductive surface formed by increasing the end face of common electrode

Claims (17)

[Claims] 1. A piezoelectric vibrator having a piezoelectric constant d31 is fixed to a fixed substrate by alternately laminating internal electrodes of two poles extending in a displacement axis direction with a piezoelectric material interposed therebetween. An ink jet recording head for expanding and contracting the volume of a pressure generating chamber communicating with a nozzle opening by supplying a driving signal to the nozzle, wherein at least a fixing surface of the piezoelectric vibrator of the fixed substrate has conductivity, and A segment electrode that is electrically independent of an adjacent piezoelectric vibrator is attached to the fixed substrate at a fixed distance from the segment electrode on a tip surface of the vibrator, a surface that is not bonded to the fixed substrate. A common electrode formed on the rear end face of the piezoelectric vibrator from the non-existing surface and thickened to such an extent that an area facing the fixed substrate can come into contact with the fixed substrate. An ink jet recording head in which the thickened area of the common electrode forms a conductive relationship with the fixed substrate. 2. The ink jet recording head according to claim 1, wherein one of the internal electrodes is exposed at a front end face of the piezoelectric vibrator, and the other of the internal electrodes is exposed at a rear end face of the piezoelectric vibrator. . 3. The ink jet recording head according to claim 1, wherein the thickened region is formed by wraparound when the common electrode is formed. 4. The ink jet recording head according to claim 1, wherein the fixed surface of the piezoelectric vibrator is an inactive area. 5. The ink jet recording head according to claim 1, wherein the fixed substrate and the piezoelectric vibrator are fixed by an adhesive. 6. The ink jet recording head according to claim 5, wherein said bonding means is a conductive adhesive. 7. The ink jet recording head according to claim 1, wherein the piezoelectric vibrator has a displacement in a longitudinal vibration mode. 8. The ink jet recording head according to claim 1, wherein said fixed substrate is made of rust-proof steel. 9. The ink jet recording head according to claim 1, wherein the fixed substrate is formed by forming a metal layer on a ceramic surface. 10. The ink jet recording head according to claim 9, wherein the piezoelectric vibrator has at least a region where a segment electrode is formed separated by a slit. 11. The ink jet recording head according to claim 1, wherein the piezoelectric vibrator has at least a region where an internal electrode exposed at a tip end surface of the piezoelectric vibrator is formed, separated by a slit. 12. The ink jet recording head according to claim 1, wherein the piezoelectric vibrator has an area in which at least a part of a rear end face of the piezoelectric vibrator is not separated by a slit. 13. The ink jet recording head according to claim 1, wherein the piezoelectric vibrator has an area in which at least a part of the common electrode of the piezoelectric vibrator is not separated by a slit. 14. The ink jet recording head according to claim 1, wherein the piezoelectric vibrators are fixed to the fixed substrate at a constant pitch. 15. A non-vibrating dummy vibrator is formed on at least one end of the row of piezoelectric vibrators.
3. The ink jet recording head according to item 1. 16. A grounding conductive pattern of the flexible cable is joined to the common electrode surface of the piezoelectric vibrator at least at one end of the row of the piezoelectric vibrator that is not bonded to the fixed substrate. Item 2. An ink jet recording head according to Item 1. 17. An internal electrode serving as one pole, an internal electrode serving as the other pole, and a piezoelectric material are alternately overlapped with each other, and only one end of each internal electrode is exposed to the front and rear ends. Stacking two piezoelectric vibrating plates via a spacer, fixing a mask material on a boundary region between the segment electrode and the common electrode on the front and rear surfaces, and depositing an external connection electrode forming material; A step of separating the two piezoelectric vibrating plates later, removing the mask material, and fixing an inactive region to a fixed substrate having at least a surface having conductivity with an adhesive; Forming a slit up to the rear end of the segment electrode; and a method of manufacturing a piezoelectric vibrator unit comprising: