JPH11105285A - Ink jet recording head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To shorten a region having no relation to vibration of a piezoelectric vibrator by simplifying an electrode structure. SOLUTION: The recording head comprises a conductive layer 26 formed on an exposure surface of at least one piezoelectric vibrator 9' to shorten internal electrodes having at least two poles. And, a connecting electrode 24 of the vibrator 9' is used as a connector of the one pole. And, electrodes 24 for external connection of the other piezoelectric vibrators 9 are used as connectors of the other pole and connected to a flexible cable.

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.

A piezoelectric vibrator A in a longitudinal vibration mode is shown in FIG.
As shown in (a), the internal electrode B serving as one pole and the internal electrode C serving as the other pole are laminated in a sandwich shape via the piezoelectric material D, and one internal electrode B is disposed on the tip side. The other internal electrode C is exposed to the rear end side and connected to the segment electrode E and the common electrode F at each end face. These piezoelectric vibrators A are arranged and fixed at a fixed pitch on a fixed substrate G as shown in FIG. 9 (b) to constitute a unit. A common electrode F is formed, a conductive pattern of the flexible cable H is connected to the common electrode F, and a signal is supplied from an external drive circuit to be driven. In addition, the code | symbol K in a figure shows the flow-path unit which discharges an ink droplet.

[0004]

The necessity of forming an electrode for connecting two poles at the rear end of such a thin piezoelectric vibrator causes a problem that the electrode structure becomes complicated and also a problem that the connection between the two poles is made. A space for arranging the electrodes in the axial direction of the piezoelectric vibrator is required, and the piezoelectric vibrator becomes longer by at least L, and further, when soldering to the flexible cable H, the solder flows into the gap J to cause bridging or short-circuiting. I have a problem. 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 recording head in which the structure of connection external electrodes is simplified.

[0005]

According to the present invention, in order to solve such a problem, internal electrodes of two poles are alternately stacked with a piezoelectric material interposed therebetween, and external electrodes for external connection are provided on a surface parallel to the arrangement direction. The piezoelectric vibrator having the electrodes formed thereon is fixed to a fixed substrate at a constant pitch, a flexible cable is connected to the external connection electrode, and a drive signal is supplied to the piezoelectric vibrator to communicate with the nozzle opening. In an ink jet recording head for expanding and contracting the volume of a generation chamber, a conductive layer that short-circuits the internal electrodes of at least two poles is formed on an exposed surface of at least one of the piezoelectric vibrators. And the external connection electrode of the other piezoelectric vibrator is connected to the flexible cable as the other pole connection.

[0006]

In each piezoelectric vibrator, one internal electrode is connected via a connection electrode formed on each of the piezoelectric vibrators, and the other internal electrode is connected to an internal electrode of the piezoelectric vibrator at an end, a conductive layer, and a connection electrode. A drive signal is received via the electrode.

[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 having a reservoir 6 for supplying ink to the pressure generating chamber 4 via an ink supply port 5, and a vibrator unit 8.
An elastic plate 10 that abuts against the tip of each piezoelectric vibrator 9 in the longitudinal vibration mode to expand and reduce 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 vibrator 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 connected to a segment electrode 24 formed by forming a conductive layer from the front end face to the vicinity of the center of the fixed substrate 16, and the other internal electrode 22 is connected to a center area on the back side to the rear end face. Common electrode 25 formed with layer
It is connected to the.

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. They are conductively connected by a conductive adhesive so as to match.

At least one end of the row of the piezoelectric vibrators 9 is provided with a dummy piezoelectric vibrator 9 'having the same configuration as the piezoelectric vibrator 9 as shown in FIG.

That is, the internal electrode 21 ′ serving as one of the poles extending from the front end side to a position just before the fixed region with the fixed substrate 16.
And an internal electrode 22 ′, which is the other pole extending from the vicinity of the front end to the rear end, is laminated in a sandwich manner via a piezoelectric material 23, and one internal electrode 21 ′ is on the front end side and the other internal electrode 22 ′ Is exposed on the rear end side, and the internal electrodes 2
1 ′ is a segment electrode 24 formed by forming a conductive layer from the front end face to the vicinity of the center of the fixed substrate 16, and the other internal electrode 22 ′ is formed by forming a conductive layer from the center area on the back side to the rear end face. Connected to the common electrode 25 and the piezoelectric vibrator 9.
It is formed slightly wider than that.

Then, the dummy piezoelectric vibrator 9 'is shown in FIG.
As shown in (a), a conductive layer 26 is formed on the side to connect the internal electrode 21 'of at least one pole to the internal electrode 22' of the other pole, or as shown in FIG. As described above, the segment electrode 24 and the common electrode 25 are connected by the conductive layer 27.

The conductive layers 26 and 27 are formed by sputtering a conductive material, applying a conductive paint, and soldering.

The segment electrode 24 and the common electrode 25 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 from which ink droplets are to be ejected passes through the conductive pattern 32 of the flexible cable 13 and the segment electrode 24. The drive signal is received by the internal electrode 21 serving as one of the electrodes, and the internal electrode 22 serving as the other electrode via the grounding conductive pattern 31, the fixed substrate 16, and the common electrode 25, and the nozzle is displaced by the piezoelectric constant d31. Opening 2
To eject ink droplets.

As described above, the common electrodes 25 of the respective piezoelectric vibrators 9 and the dummy piezoelectric vibrators 9 'and 9' are connected by the fixed substrate 16 and connected to the common electrode 25 of the dummy piezoelectric vibrator 9 '. Is electrically connected to the segment electrode 23 'via the internal electrode 22', the conductive layer 26, and the other internal electrode 21 '.
To the ground conductive pattern 31.

Next, a method of manufacturing the above-described vibrator unit 8 will be described with reference to FIG. Conductive material 41 serving as an internal electrode serving as one pole extending from the tip to the end of the active region
A piezoelectric vibrating plate 44 formed by laminating a conductive material 42 serving as an internal electrode serving as the other electrode extending from the rear end to the vicinity of the front end while sandwiching the piezoelectric material 43, drying and firing is prepared. 45, a common electrode 46 is formed, and a conductive layer 47 is formed on both sides so as to connect at least the conductive materials 41 and 42. In addition, a fixed substrate 48 made of a conductive material such as a metal or a plate having at least a conductive layer formed on the surface is prepared (FIG. 7I).

A region in which only the conductive layer 42 serving as the other internal electrode is formed, that is, an inactive region is positioned on the fixed substrate 48, and the piezoelectric vibration plate 44 is fixed to the fixed substrate 48 with a conductive adhesive ( FIG. 7 (II)).

Next, a slit 50 is formed from the free end side tip to at least the rear end side of the conductive layer 41 to be a segment electrode by a dicing saw or wire saw cutting tool 49.
After forming and separating 50, 50, and ‥‥, the vibrator unit is completed.

When forming the slits 50, 50, 50,..., Both ends are cut out slightly wide to form dummy piezoelectric vibrators 9 ', 9' wide, When the conductive layer 41 is formed in a continuous state, that is, in a comb shape, the common electrode of the piezoelectric vibrator 9 and the dummy piezoelectric vibrator 9 ′ is connected to the conductive layer 41 regardless of the conductivity of the fixed substrate 48. Can be electrically connected.

The internal electrode extending to the inactive region side is formed so as to connect the piezoelectric vibrator and the dummy piezoelectric vibrator in parallel without being cut by the slit. As shown in FIGS. 7A and 7B, a common electrode connected to the other internal electrode is not required, so that the internal electrode of the dummy piezoelectric vibrator 9 'or the internal electrode and the segment electrode Should be connected.

In the above-described embodiment, the piezoelectric constant d31 in which the internal electrode is formed in parallel to the direction of displacement of the piezoelectric vibrator.
The internal electrodes 52 and 53 are formed perpendicularly to the direction of displacement and alternately so as to be exposed on one side, respectively, as shown in FIG. Segment electrode 54 formed on the surface side and common electrode 5
In the vibrator unit in which the piezoelectric vibrators 56 having the piezoelectric constant d33 connected to the piezoelectric vibrator 5 are arranged and fixed at a fixed pitch on the fixed substrate 57, the piezoelectric vibrator 56 as shown in FIGS. Of the dummy piezoelectric vibrator 56 ′ or the internal electrodes 52 ′, 53 ′, the segment electrode 54, and the common electrode 55 which are arranged at at least one end of the dummy piezoelectric vibrator 56 ′. The same effect can be obtained by forming the layers 58, 58.

[0026]

As described above, according to the present invention, a conductive layer for short-circuiting the internal electrodes of at least two poles is formed on at least the exposed surface of the piezoelectric vibrator, and the piezoelectric vibrator is connected to one of the poles. As a connecting portion, an electrode for external connection of another piezoelectric vibrator is connected to a flexible cable as a connecting portion of the other pole, so that one electrode for connecting one pole is provided at the rear end of the thin piezoelectric vibrator. , It is possible to simplify the electrode structure, shorten the area not involved in the vibration of the piezoelectric vibrator, and prevent short-circuiting during soldering with the flexible cable as much as possible.

[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.

FIGS. 3A and 3B are cross-sectional views showing a connection structure between a dummy piezoelectric vibrator of the recording head and a flexible cable, respectively.

FIGS. 4A and 4B are perspective views showing one embodiment of a vibrator unit used in the recording head according to the first embodiment, as viewed from the front and back.

FIG. 5 is a diagram showing one embodiment of a flexible cable suitable for connecting the vibrator unit and an external drive circuit.

FIGS. 6 (I) to (III) are diagrams showing manufacturing steps of a vibrator unit used for the recording head, respectively.

FIGS. 7A and 7B are diagrams showing another embodiment of the present invention in the form of a dummy piezoelectric vibrator. FIG.

FIG. 8 (a) shows an embodiment of a piezoelectric vibrator having a piezoelectric constant d33, and FIGS. 8 (b) and 8 (c) show another embodiment of the present invention in the form of a dummy piezoelectric vibrator. FIG.

FIGS. 9A and 9B are diagrams showing a conventional ink jet recording head and a vibrator unit used for the same, respectively.

[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 21, 21' Internal electrode forming one pole 22, 22 'Internal electrode forming the other pole 23 Piezoelectric material 24 segment electrode 25 common electrode 26, 27 conductive layer

Claims (18)

[Claims] An internal electrode of two poles is alternately stacked with a piezoelectric material interposed therebetween, and a piezoelectric vibrator having electrodes for external connection formed on a surface parallel to the arrangement direction is fixed to a fixed substrate at a constant pitch. An ink jet recording head for connecting a flexible cable to the external connection electrode and supplying a drive signal to the piezoelectric vibrator to expand and contract the volume of the pressure generating chamber communicating with the nozzle opening; Forming a conductive layer on the exposed surface of the piezoelectric vibrator that short-circuits the internal electrodes of at least two poles,
An ink jet recording head in which the piezoelectric vibrator is connected to one of the poles, and the external connection electrode of the other piezoelectric vibrator is connected to the flexible cable as the other pole. 2. The conductive layer according to claim 1, wherein a conductive layer for short-circuiting the internal electrodes of at least two poles is formed on an exposed surface of the piezoelectric vibrator disposed at an end of the piezoelectric vibrator in a row direction. The ink jet recording head according to the above. 3. A conductive layer that short-circuits the internal electrodes of at least two poles is formed on an exposed surface of at least one of the piezoelectric vibrators, and the piezoelectric vibrator is used as a connection part of one of the poles, and the other is connected to another of the piezoelectric vibrators. 2. The ink jet recording head according to claim 1, wherein the electrode for external connection of the piezoelectric vibrator is connected to the flexible cable as a common electrode of the piezoelectric vibrator. 4. The ink jet recording head according to claim 1, wherein the conductive layer is formed so as to connect the external connection electrode. 5. The ink jet recording head according to claim 1, wherein electrodes for external connection provided on the fixed substrate side of the piezoelectric vibrator are connected in parallel via a conductive member. 6. The ink jet recording head according to claim 5, wherein the conductive member is the fixed substrate. 7. The ink jet recording head according to claim 5, wherein the fixed substrate and the electrode for external connection are joined via a conductive adhesive. 8. The ink jet recording head according to claim 6, wherein said fixed substrate is made of metal. 9. The ink jet recording head according to claim 6, wherein the fixed substrate is made of ceramic having a metal layer on at least the surface. 10. A dummy piezoelectric vibrator is provided on at least one end in the direction in which the piezoelectric vibrators are arranged, and internal electrodes of two poles of the dummy piezoelectric vibrator are short-circuited by a conductive layer. Item 2. An ink jet recording head according to Item 1. 11. The ink jet recording head according to claim 1, wherein the dummy piezoelectric vibrator is configured to be wider than other piezoelectric vibrators. 12. The ink jet recording head according to claim 1, wherein the piezoelectric vibrator has a longitudinal vibration mode that expands and contracts in an axial direction. 13. The internal electrode is formed parallel to the direction of displacement of the piezoelectric vibrator, and the internal electrode forming one pole is exposed at one end and is formed to a certain distance from the other end,
2. The ink jet recording head according to claim 1, wherein the internal electrode forming the other pole is exposed at the other end, and is formed to a certain distance from the one end to form a piezoelectric constant d31. 14. The internal electrode is formed so as to be orthogonal to the direction of displacement of the piezoelectric vibrator, and the internal electrode forming one pole is formed on one of the electrodes for external connection, and the internal electrode forming the other pole is formed on the other. 2. The ink jet recording head according to claim 1, wherein the recording head is connected to the other of the external connection electrodes and configured as a piezoelectric constant d33. 15. The ink jet recording head according to claim 13, wherein a vibration region is slit by a slit so as to leave the internal electrode exposed on the rear end side. 16. The ink jet recording head according to claim 15, wherein only electrodes for external connection are connected to the internal electrodes exposed at the tip of the piezoelectric vibrator on the vibration side. 17. The ink jet recording head according to claim 1, wherein the external electrode connected to the internal electrode exposed at the vibration-side tip of the piezoelectric vibrator is located closer to the center than the other end of the piezoelectric vibrator. . 18. The ink jet recording head according to claim 1, wherein the conductive layer is formed by sputtering a conductive material, a conductive paint, and soldering.