JPH11138812A - Ink-jet type recording head, and manufacture of piezoelectric vibrator unit used in the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a shortcircuit or an electric conduction of internal electrodes because of a brake of an edge part, etc. SOLUTION: A distance L2 between a leading end 2a' of an internal electrode 2', 2' positioned at the outer side among internal electrodes 2, 2' buried in a piezoelectric material 4 spaced by a constant distance L2 from a leading end of a piezoelectric vibrator 5 at the side of a passage unit, and a leading end face of the piezoelectric vibrator 5 is set larger than a distance between a leading end of the other internal electrode 2, 2... of the same polarity and the leading end face of the piezoelectric vibrator. A long distance is secured between the internal electrode 2' at an edge part which is easy to brake and an external electrode 9 connected to an internal electrode 3 of the other polarity, thereby preventing an electric conduction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet recording head using, as a pressure generating means, a longitudinal vibration mode piezoelectric vibrator in which a plurality of internal electrodes are alternately laminated with a piezoelectric material interposed therebetween.

[0002]

2. Description of the Related Art As shown in FIG. 9A, an ink jet recording head using a piezoelectric vibrator in a longitudinal vibration mode has a flow path forming substrate D having a pressure generating chamber A, an ink supply port B, and a reservoir C. A channel unit H in which an elastic plate E sealing one surface of the channel forming substrate D and a nozzle plate G having a nozzle opening F communicating with the pressure generating chamber A are stacked;
A piezoelectric vibrator unit having two members, a piezoelectric vibrator unit J, and a piezoelectric vibrator K constituting the piezoelectric vibrator unit J, causing the pressure generating chamber A to expand and contract to discharge ink droplets from the nozzle openings F. In the piezoelectric vibrator K, internal electrodes L and M of two poles are laminated so as to wrap through a piezoelectric material N in a vibration region, and external electrodes P and Q are formed so as to be connected to each internal pole. It is configured.

In such a piezoelectric vibrator K, a plurality of large-sized piezoelectric vibrating plates are prepared, which are cut into small plates corresponding to the size of a vibrator unit, and external electrodes P and Q are applied to each small plate. The piezoelectric vibrating plate of each small plate is formed with a slit at a constant pitch by a wire saw or the like so that a continuous portion is left at one end.

However, at the stage of manufacturing a large-sized piezoelectric vibrating plate, chipping or the like occurs at the corners in the step of laminating or firing the piezoelectric material. Then, as shown in FIG. 9 (b), a conductive material layer is also formed on the deficient portion R, and the internal electrodes L,
There is a problem that M conducts between the different poles and causes malfunction.

Although a piezoelectric vibrator unit having such a malfunction is not necessarily incorporated as a component of a recording head due to a strict inspection, it is necessary to improve the recording density of the recording head. As the size becomes smaller, there is a problem that the production yield is rapidly reduced.

The present invention has been made in view of such a problem, and an object of the present invention is to improve the yield by minimizing a malfunction of a piezoelectric vibrator due to a defect in an edge region of the piezoelectric vibrator. The object of the present invention is to provide an ink jet recording head capable of performing the following.

Another object of the present invention is to propose a method of manufacturing a piezoelectric vibrator unit used in an ink jet recording head.

[0008]

SUMMARY OF THE INVENTION In order to solve such a problem, according to the present invention, a first internal electrode and a second internal electrode of different poles are exposed only at respective end faces in parallel in the axial direction. A piezoelectric vibrator having a piezoelectric constant d31 laminated with a piezoelectric material interposed therebetween so as to wrap in a vibration region, and an elastic plate which abuts on the tip of the piezoelectric vibrator to expand and reduce the volume of the pressure generating chamber And a flow path unit having: a first internal electrode embedded in the piezoelectric material at a predetermined distance from a front end of the piezoelectric vibrator on the flow path unit side, outside of the first internal electrode embedded in the piezoelectric material. The distance between the tip of the piezoelectric element and the tip face of the piezoelectric vibrator is set to be larger than the distance between the tip of the other first internal electrode and the tip face.

[0009]

The distance between the first internal electrode and the external electrode connected to the second internal electrode at the edge where chipping is likely to occur is long, so that even if a conductive layer for the external electrode is formed in the defective part, the other electrode may not be formed. Contact with the first internal electrode, which is a pole, is prevented.

[0010]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing a first embodiment of the present invention. FIG. 1 shows an embodiment of the present invention. A piezoelectric vibrator unit 1 according to the present invention includes an internal electrode 2 having different poles parallel to an axial direction.
The piezoelectric vibrators 5 are laminated with a piezoelectric material 4 interposed therebetween so as to expose one end of each of the piezoelectric vibrators 3 and wrap in the vibrating region.
Are arranged on the fixed substrate 6 at a constant pitch as shown in FIG. Reference numerals 7 in the drawing denote dummy piezoelectric vibrators for positioning the piezoelectric vibrator unit provided at the ends of the piezoelectric vibrators in the row direction.

From the exposed surfaces of the internal electrodes 2 and 3 at the front and rear ends of each piezoelectric vibrator 5 to the front side of the fixed substrate 6, external electrodes 9 forming connection portions with a flexible cable 8 for supplying a drive signal are provided. And 10 are formed by vapor deposition or sputtering.

An internal electrode 2 ′, which is exposed at the rear end of the piezoelectric vibrator 5 and whose end 2 a is buried in the piezoelectric material 4 at the front end,
Of the 2, 2 and ‥‥, those 2 ′ located outside are formed such that the distance L1 from the tip surface is larger than the distance L2 between the other internal electrodes 2, 2, ‥‥ and the tip surface. ing.

The channel forming unit 11 includes a reservoir 12,
A flow path forming substrate 15 that partitions and forms the ink supply port 13 and the pressure generating chamber 14, and an elastic plate 16 that abuts against the tip of the piezoelectric vibrator 5 to expand and reduce the volume of the pressure generating chamber 14.
And a nozzle opening 1 for sealing the other surface of the flow path forming substrate 15 and discharging the ink in the pressure generating chamber 14 as ink droplets.
And a nozzle plate 18 provided with the nozzle 7.

The flow path forming unit 11 includes the head holder 1
The piezoelectric vibrator unit 1 is fixed to the opening surface 19a of the piezoelectric vibrator 9 and the elastic plate 1
6, the fixed substrate 6 and the head holder 19 are fixed by an adhesive to form an ink jet recording head.

In this embodiment, when a drive signal is applied to the piezoelectric vibrator 5 facing the pressure generating chamber 14 communicating with the nozzle opening 17 from which ink droplets are to be ejected, the piezoelectric vibrator 5 contracts and expands, and the pressure is increased. The generation chamber 14 is expanded and contracted. As a result, the ink in the reservoir 12 is
3 flows into the pressure generating chamber 14, and then the ink in the pressure generating chamber 14 is pressurized and discharged from the nozzle opening 17 as an ink droplet.

By the way, in the process of manufacturing a large-sized piezoelectric diaphragm, chipping or the like may occur at an edge portion. When the external electrode 9 is formed by vapor deposition or sputtering of a conductive material in a state where the chipping is present, a conductive layer 9 ′ is also formed at the defect R as shown in FIG.
Internal electrode 2 ′ located on the outside of the internal electrodes 2, 2
Is located at the rear end of the deficient portion R with respect to the internal electrode located inside, the conductive layer 9 ′ is not formed over the internal electrode 2 and the internal electrode 3 of another pole with a slight chipping. Therefore, the internal electrodes of different poles do not cause a situation such as conduction.

In the above-described embodiment, only the outermost inner electrodes 2 'and 2' are retracted. However, as shown in FIG. When the internal electrode 2 located at the center is made the longest and the internal electrodes 2 ″ and 2 ′ that are away from the center are formed so as to be shorter, the internal electrodes having different polarities due to the conductive layer formed in the defective portion are formed. Can be prevented more reliably.

Further, as shown in FIG. 4B, the layer thickness G of the piezoelectric material 4 between the inner electrode 2 'and the outer electrode 9 which are not exposed at the tip and which are located on the outermost side is changed to the other inner electrodes. When the thickness is larger than the layer thickness of the piezoelectric material 4 sandwiched between the electrodes, conduction between the internal electrodes having different polarities due to the conductive layer formed in the defective portion can be more reliably prevented as in FIG.

FIGS. 5 to 7 show such a piezoelectric vibrator 5.
In this embodiment, a green sheet 21 of a piezoelectric material having a size corresponding to a plurality of sheets and formed in advance to a thickness of each layer is placed on a surface plate 20 having a flat surface. (FIG. 5 (I)).

The outermost pattern of one of the internal electrodes 3 on the surface thereof, that is, the tip 21 of the green sheet
A layer 22 of a conductive material is formed using a mask having a pattern in which only L1 is a non-forming region from a (FIG. 5 (I
I)), Green sheet 2 of piezoelectric material of the same size as above
1 (FIG. 5 (III)).

Using a mask provided with a pattern for forming the internal electrode 3 serving as the other pole, the conductive material layer 23 is formed so that the width L3 corresponding to the vibrating region is set as the forming region from the end 21a of the green sheet. Is formed (FIG. 6 (I)), and a green sheet 21 of a piezoelectric material having the same size as that described above is laminated (FIG. 6 (II)).

A layer 22 'of a conductive material is formed using a mask having a pattern in which only L2 is not formed from the front end 21a of the green sheet (FIG. 6 (III)). When such a process is repeated to form another outer electrode 2 ′ which is the outermost one of the internal electrodes which become one pole,
As in the step of FIG. 5 (II), the front end 21a of the green sheet
Then, a layer 22 of a conductive material is formed using a mask having a pattern in which only the area from L1 to L1 is not formed, and a green sheet 21 of a piezoelectric material is overlaid. At the stage where the lamination has been completed to a predetermined thickness, the green sheet is dried and then fired.

As a result, a plurality of piezoelectric vibrating plates are completed. External electrodes 33 and 36 serving as electrodes for connection to a flexible cable are formed on the surface by sputtering or vapor deposition, and a voltage is applied to these electrodes 33 and 36. Is applied to perform a predetermined polarization process, and then cut into small plates of a size corresponding to the piezoelectric vibrator unit.

The piezoelectric material plate 30 cut into small plates is positioned on a fixed substrate 31 (FIG. 7 (I)) and fixed with an adhesive (FIG. 7 (II)). The piezoelectric vibrator 5 is completed by forming a slit 35 with a cutting means 34 such as a wire saw from the tip and dividing the conductive layer 23 so that the conductive layer 23 and the external electrode layer 33 can be separated from each other. . In addition, slit 3
5 is formed so that its end is oblique to the arrangement surface of the piezoelectric vibrators as shown in the figure, or is formed so as to be perpendicular.

As described above, the external electrode 33 is formed as a select electrode by forming the slit 35 in a state where the external electrode layer 33 on the front end side can be separated and the external electrode 36 on the rear end side can be connected. In addition, the external electrode 36 can be used as a common electrode having as small an electric resistance as possible.

In the above embodiment, the inactive region of the piezoelectric vibrator is fixed to the fixed substrate. However, as shown in FIG. It is clear that the same effect is obtained even if the fixing is performed.

[0027]

As described above, in the present invention,
Of the first internal electrodes embedded in the piezoelectric material at a fixed distance from the front end of the piezoelectric vibrator on the side of the flow path unit, the distance between the front end of the first internal electrode and the front end surface of the piezoelectric vibrator is different from that of the other. Since the first internal electrode is formed larger than that of the first internal electrode, a long distance can be secured between the first internal electrode at the edge portion where chipping is likely to occur and the external electrode connected to the second internal electrode. The contact of the portion with the conductive layer for the external electrode can be prevented.

[Brief description of the drawings]

FIGS. 1A and 1B are a cross-sectional view showing an embodiment of an ink jet recording head according to the present invention, and an enlarged view showing a tip of a piezoelectric vibrator.

FIG. 2 is a perspective view showing one embodiment of a piezoelectric vibrator unit used for the recording head.

FIG. 3 is an enlarged view showing a tip of a piezoelectric vibrator of the piezoelectric vibrator unit.

FIGS. 4A and 4B are diagrams showing another embodiment of the ink jet recording head of the present invention in the form of a piezoelectric vibrator.

FIGS. 5 (I) to (III) are diagrams showing the first half of a method for manufacturing a piezoelectric vibrating plate in the method for manufacturing a piezoelectric vibrator unit according to the first embodiment.

FIGS. 6 (I) to (III) are views showing the latter half of the method of manufacturing the piezoelectric vibrating plate in the method of manufacturing the piezoelectric vibrator unit.

FIGS. 7 (I) to (III) are diagrams showing steps of forming a piezoelectric vibrator using a piezoelectric vibrating plate in the method of manufacturing the piezoelectric vibrator unit of the above.

FIG. 8 is a perspective view showing another embodiment of the present invention.

FIGS. 9A and 9B are enlarged views of a conventional ink jet recording head and a tip of a piezoelectric vibrator thereof.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Piezoelectric vibrator unit 2, 2 'Internal electrode of one pole 3 Internal electrode of the other pole 4 Piezoelectric material 5 Piezoelectric vibrator 6 Fixed substrate 11 Flow path forming unit 12 Reservoir 13 Ink supply port 14 Pressure generation chamber 17 Nozzle opening R missing part

Claims (16)

[Claims] 1. A first internal electrode and a second internal electrode having different polarities in parallel in an axial direction are respectively exposed only at respective end faces, and are laminated with a piezoelectric material interposed therebetween so as to wrap in a vibration region. A piezoelectric vibrator having a piezoelectric constant d31, and a flow path unit having an elastic plate which abuts on the tip of the piezoelectric vibrator to expand and reduce the volume of the pressure generating chamber. Of the first internal electrodes embedded in the piezoelectric material at a fixed distance from the front end of the piezoelectric element on the side of the flow path unit, the distance between the front end of the first internal electrode and the front end surface of the piezoelectric vibrator is other than An ink jet recording head formed to be larger than the distance between the tip of the first internal electrode and the tip surface. 2. A flow path unit, wherein a flow path unit partitions and forms a reservoir, an ink supply port, and a pressure generation chamber, and a volume of the pressure generation chamber is expanded by contacting a tip of the piezoelectric vibrator. 2. A liquid-tight stack comprising: an elastic plate to be contracted; and a nozzle plate having a nozzle opening for discharging an ink droplet by sealing the other surface of the flow path forming substrate. Inkjet recording head. 3. The ink jet recording head according to claim 1, wherein the distance between the first internal electrode and the front end surface of the piezoelectric vibrator is set to be gradually longer so that a central region is a vertex. 4. The ink jet recording head according to claim 1, wherein the layer of the piezoelectric material outside the outermost first internal electrode is formed thicker than between the internal electrodes in other regions. . 5. A first internal electrode of each of the piezoelectric vibrators is connected in parallel at an end surface of a non-vibration region, and a second internal electrode of each of the piezoelectric vibrators is connected in parallel at an end surface of a vibration region. 2. The ink jet recording head according to claim 1, further comprising an external electrode. 6. The ink-jet type according to claim 5, wherein the external electrode connected to the first internal electrode is connected as a common electrode, and the external electrode connected to the second internal electrode is connected to a flexible cable as a select electrode. Recording head. 7. An external electrode connected to the first internal electrode,
The ink jet recording head according to claim 5, wherein the ink jet recording head is connected in parallel with all of the piezoelectric vibrators constituting the piezoelectric vibrator unit. 8. The ink jet recording head according to claim 1, wherein the piezoelectric vibrator has a non-vibration area fixed to a fixed substrate to constitute a piezoelectric vibrator unit. 9. The ink jet recording head according to claim 5, wherein the piezoelectric vibrator has a side surface of the non-vibration region fixed to the fixed substrate. 10. The ink jet recording head according to claim 5, wherein said piezoelectric vibrator has an end surface of said non-vibration region fixed to said fixed substrate. 11. A piezoelectric element having a piezoelectric constant d31 in which the piezoelectric vibrator is laminated with a piezoelectric material interposed therebetween such that internal electrodes of different poles are exposed at one end in parallel with the axial direction and wrapped in a vibration region. 2. The ink jet recording head according to claim 1, wherein a slit is formed in the diaphragm. 12. The ink jet recording head according to claim 11, wherein the slit is formed in a vibration area. 13. The ink jet recording head according to claim 12, wherein an end face of the slit is inclined with respect to an arrangement surface of the piezoelectric vibrators. 14. The ink jet recording head according to claim 12, wherein an end face of the slit is perpendicular to an arrangement surface of the piezoelectric vibrators. 15. A piezoelectric material having a predetermined size and thickness,
On one end face of the piezoelectric material, the one located on the outside,
A layer of a first conductive material that leaves a wide non-forming region, and a second layer that leaves a non-forming region of a constant width on the other end surface of the piezoelectric material.
A step of alternately forming layers of a conductive material, a step of baking when the lamination to a predetermined thickness is completed, a step of forming external electrodes for connection on the surface, and fixing the non-vibration region to the fixed substrate Forming a slit so as to leave a continuous portion on the non-vibration area side, and splitting the teeth, thereby manufacturing a piezoelectric vibrator unit for an ink jet recording head. 16. The method according to claim 15, wherein the slit is formed so as to leave a continuous portion in a non-vibration area.