JPH10272775A - Piezoelectric member for ink jet recording head and formation thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the generation of an electric field in a piezoelectric plate in a direction different from a regular electric field in a piezoelectric member for an ink jet recording head. SOLUTION: A conductive layer 50 provided on one opposed surface of a piezoelectric plate 45 is divided into a common electrode 47, a common outgoing electrode 52 and an individual outgoing electrode 53 and a notched groove 60 is provided so that the bottom part thereof is positioned within the piezoelectric plate 45. The piezoelectric plate 45 of the part held between the common electrode 47 and the individual electrode 48 composed of the conductive layer formed to the other surface of the piezoelectric plate 45 is subjected to polarizing treatment to be set to an active region.

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 for ejecting ink droplets in accordance with an image signal and attaching the ink droplets to a recording medium such as recording paper to record an image. The present invention relates to a piezoelectric member for an ink jet recording head to be used.

[0002]

2. Description of the Related Art FIG. 7 shows an example of a conventional ink jet recording head. In this ink jet recording head, an ink cavity 4, an inklet 5, and an ink supply chamber 6 are formed by a nozzle plate 2 provided with nozzles 1 and a cavity forming member 3. A single-layer piezoelectric member 10 is fixed between the partition wall 7 covering the lower surface of the cavity forming member 3 and the substrate 8 so as to face each ink cavity 4. The conductive layer 11 provided on the upper surface of the substrate 8 is divided by a cut groove 12, and one of the divided conductive layers 11 is connected to the common electrode 15 of the piezoelectric member 10.
And the common lead-out electrode 16, and the other part constitutes the individual lead-out line 17. This individual lead 17 is
It is connected to an individual electrode 19 on the upper surface of the piezoelectric plate 13 via an individual conductive layer 18 formed on one side surface of the piezoelectric plate 13. The common lead electrode 16 is connected to the ground, and the individual lead electrodes 17 are connected to an image signal control circuit (not shown).

When a voltage is applied to the individual electrode 19 from the image signal control circuit, the individual electrode 19 and the common electrode 15 are polarized regions (the active region 21) opposed to each other with the piezoelectric plate 13 interposed therebetween.
Then, the electric field E1 from the common electrode 15 to the individual electrode 19
Is generated, and the piezoelectric plate 13 instantaneously expands in the thickness direction to push up the partition wall 7. As a result, the ink in the ink cavity is pressurized and ejected from the nozzle 1 as ink droplets.

[0004]

When a voltage is applied to the individual electrode 19, in addition to the regular electric field E1, the region outside the active region 21 (the non- Individual extraction electrode 20 in active region 22)
, An electric field E2 is generated toward the front end of the device. The piezoelectric plate 13 is deformed in the longitudinal direction by the electric field E2. Further, an oblique electric field E3 is generated from the common electrode 15 toward a portion of the individual electrode 19 located in the inactive region 23, and the electric field E3 deforms the piezoelectric plate 13 in the oblique direction.

[0005] Even when a voltage other than the voltage causing the electric field E1 does not act on the piezoelectric member 10, even if the electric field E1 is not applied.
In the direction perpendicular to the direction, a force for contracting the piezoelectric member 10 acts,
The piezoelectric member 10 is designed in consideration of the strain due to this force. However, when the electric fields E2 and E3 in the direction different from the normal electric field E1 are generated in the piezoelectric plate 13 as described above, a force to deform the piezoelectric plate 13 in a direction different from the thickness direction, which is its original deformation direction, acts. I do. As a result, cracks may occur in the portion of the piezoelectric plate 13 facing the cut grooves 12, and the common electrode 15 and the individual electrode 19 may be broken. In addition, a loss is generated in the displacement amount of the piezoelectric plate 13 in the thickness direction due to the deformation due to the electric fields E2 and E3,
It becomes difficult to accurately control the displacement of the piezoelectric plate 13.

On the other hand, if the piezoelectric plate 13 is
Is not provided, the piezoelectric plate 1 in the active region 21 is not provided.
3 does not deform in a direction different from the direction of the normal electric field E1. However, if there is no supporting member for the partition 7, when the partition 7 in the active region 21 is displaced, the partition 7 in the non-active region 22 is also displaced, so that the ink discharge amount cannot be accurately controlled. Therefore, it is necessary to provide the piezoelectric plate 13 also in the inactive region 22. Further, by using the electrodes in this portion, wiring for the individual electrodes can be easily provided.

The present invention has been made in view of the above-mentioned conventional problems, and has as its object to prevent generation of an electric field in a direction different from a normal electric field on the piezoelectric plate of the piezoelectric member without complicating the wiring structure of the electrodes. And

[0008]

SUMMARY OF THE INVENTION Accordingly, the present invention comprises a piezoelectric plate having opposing surfaces, a first electrode and a second electrode respectively provided on the opposing surfaces, and a voltage applied to the electrodes. Is applied, the piezoelectric member is deformed in the direction facing the electrodes, and the ink is pressurized and ejected by the deformation, and the first electrode is provided on one surface of the piezoelectric plate. Is divided into a first electrode portion and a second electrode portion, and a groove cut out so that the bottom is located inside the piezoelectric plate is provided, and the first or second electrode portion and An object of the present invention is to provide a piezoelectric member for an ink jet recording head, characterized in that a portion of the piezoelectric plate sandwiched by a second electrode provided on the other facing surface of the piezoelectric plate is polarized.

Further, according to the present invention, there is provided a piezoelectric plate having a first surface and a second surface opposed to each other, and after covering the first surface with a first electrode layer, forming the first surface. In addition, while dividing the first electrode layer into a third electrode layer and a fourth electrode layer and forming a groove cut so that the bottom is located inside the piezoelectric plate, The second surface is covered with a second electrode layer, a voltage is applied to the second electrode layer and the third or fourth electrode layer, and a portion of the piezoelectric plate sandwiched between these electrode layers is polarized. An object of the present invention is to provide a method for forming a piezoelectric member for an ink jet recording head, which comprises forming an active region by processing.

Specifically, in the above-mentioned forming method, a substrate having a flat surface is prepared, the surface of the substrate is covered with a conductive layer, and the conductive layer is applied to the first electrode portion and the second electrode portion. While forming a linear first groove to divide, the opposing first groove is formed.
A piezoelectric plate having a surface and a second surface is prepared, and a linear second groove cut toward the second surface is formed in the first surface of the piezoelectric plate. A first surface of the piezoelectric plate is fixed to a surface of the substrate such that the second groove and the first groove of the substrate face each other, and a second surface of the piezoelectric plate located on the opposite side to the substrate;
After covering the end face of the piezoelectric plate on the first or second electrode portion side with an electrode layer, the piezoelectric plate is divided into a plurality of piezoelectric members extending in a direction orthogonal to the first and second grooves. And the first or second electrode layer and the second piezoelectric layer
An active region is formed by subjecting the portion of the piezoelectric plate sandwiched by the electrode layers provided on the surface to polarization treatment.

Alternatively, a substrate having a flat surface is prepared, the surface of the substrate is covered with a conductive layer, and the conductive layer is divided into a first electrode portion and a second electrode portion. While forming the groove, a piezoelectric plate having a first surface and a second surface opposed to each other is prepared, and the first surface of the piezoelectric plate is fixed to the surface of the substrate, and is located on the side opposite to the substrate. The second surface of the piezoelectric plate to be formed and the end surface of the piezoelectric plate on the first or second electrode layer side are covered with an electrode layer, and the electrode layer provided on the first surface of the piezoelectric plate is replaced with a third electrode layer. And a fourth electrode layer, and after forming a linear second groove cut so that the bottom is located inside the piezoelectric plate, the piezoelectric plate is divided into the first and second grooves. The piezoelectric member is divided into a plurality of piezoelectric members extending in a direction perpendicular to the groove, and the first or second electrode layer and the third plate of the piezoelectric plate opposed thereto are divided.
Alternatively, the active region may be formed by polarizing the portion of the piezoelectric plate sandwiched between the fourth electrode layer and the fourth electrode layer.

[0012]

In the piezoelectric member for an ink jet recording head according to the present invention, the first electrode provided on one side of the piezoelectric plate is divided and a groove cut into the inside of the piezoelectric plate is provided. The region and the inactive region are electrically separated reliably. In other words, by providing this groove, the generation of an electric field from the electrode in the active region to the electrode in the non-active region is prevented. Therefore, in the piezoelectric member of the present invention, the force for deforming the piezoelectric plate in a direction different from the normal deformation direction is greatly reduced, and as a result, cracks in the piezoelectric plate occur,
The electrode is prevented from breaking. Further, since the loss of the displacement amount of the piezoelectric plate in the thickness direction is reduced, the control accuracy of the pressure applied to the ink is improved.

Further, since the active region and the non-active region of the piezoelectric plate are electrically separated by the cut grooves as described above, the electrodes can be freely wired to the piezoelectric plate in the non-active region. The electrode wiring structure is simple.

[0014]

Embodiments of the present invention will be described below with reference to the accompanying drawings. 1 to 3 show an ink jet recording head 24 according to an embodiment of the present invention. The head 24 includes a large-diameter ink droplet discharging head (hereinafter, referred to as “large-diameter head”) 25 and a small-diameter ink droplet discharging head (hereinafter, referred to as “small-diameter head”) 26. Nozzle plate 27, cavity forming member 28, partition wall 29, piezoelectric member 30, and substrate 3
2 are integrally formed.

The nozzle plate 27 is made of a thin plate such as a metal or a synthetic resin. The large-diameter head 25 and the small-diameter head 26 are provided with a plurality of nozzles 34, which communicate with ink cavities 40, which will be described later, by excimer laser processing.
35 are provided. The large-diameter head section 25 and the small-diameter head section 26 have the same configuration except that the nozzle 34 of the large-diameter head section 25 has a larger diameter than the nozzle 35 of the small-diameter head section 26. Are configured symmetrically.

In a lower portion of the nozzle plate 27, a cavity forming member 28 in which a plurality of long grooves penetrating vertically is formed.
Is fixed, and a partition wall 29 is fixed below it.
A plurality of ink cavities 40 for storing ink, an ink supply chamber 41 for storing replenishment ink, and an ink for communicating these are provided inside long grooves of the cavity forming member 28 which are vertically covered by the nozzle plate 27 and the partition wall 29. An inlet 42 is formed.

A piezoelectric member 30 is fixed at a position facing the ink cavity 40 between the partition wall 29 and a substrate 32 made of a flat plate made of ceramic, metal, synthetic resin or the like. Note that, as shown in FIG. 3, support portions 43 are provided between the piezoelectric members 30, and are separated by grooves 44. The piezoelectric member 30 is of a single-layer type, and a conductive layer forming a common electrode 47 and an individual electrode 48 is formed on an upper surface and a lower surface of a piezoelectric plate 45 made of a known piezoelectric material, respectively. The conductive layer 50 provided on the lower surface of the piezoelectric plate 45, that is, on the upper surface of the substrate 32 has two cut grooves 5 forming discontinuous portions.
1, 51. These two kerfs 5
The portion of the conductive layer 50 sandwiched between the first and the first electrodes 51 is the common electrode 4
7 and the common extraction electrode 52. The conductive layer 50 outside the cut grooves 51, 51 constitutes the individual extraction electrode 53. On the other hand, the conductive layer formed on the upper surface of the piezoelectric plate 45 constitutes the individual electrode 48, and the individual electrode 48 is connected to the individual extraction electrode 53 via the individual conductive layer 54 provided on one side of the piezoelectric plate 45. It is connected.

The common electrode 47 of each piezoelectric member 30 is connected to ground via a common lead electrode 52, and the individual electrode 48
Are connected to an image signal control circuit (not shown) via an individual conductive layer 54 and an individual lead electrode 53. In a region where the piezoelectric plate 45 is sandwiched between the common electrode 47 and the individual electrode 48, a high voltage is applied between these electrodes at a high temperature to polarize the piezoelectric plate 45 to form an active region 56. doing. On the other hand, in the non-active region 57 outside the active region 56, the piezoelectric plate 45 is not polarized.

The lower surface of the piezoelectric plate 45 is cut at a position facing the cut groove 51, that is, at a boundary position between the active region 56 and the non-active region 57 so that the bottom thereof is located inside the piezoelectric plate 45. A straight cut groove 60 is provided. This cut groove 60 has a rectangular cross-section, and FIG.
As shown in the figure, the width t1 is set to be larger than the width t2 of the cut groove 51. Width t1 and depth d of cut groove 60
Is appropriately set according to the thickness of the piezoelectric plate 45 and the like, but the width t
1 is about 100 μm to 1000 μm and depth d is 50 μm
It is preferably about 500 μm.

Each of the piezoelectric members 30 is supplied from the image signal control circuit.
When a voltage is applied to the individual electrodes 48 of the
6, the electric field E from the common electrode 47 to the individual electrode 48
1 occurs, and the piezoelectric plate 45 instantaneously extends in the thickness direction and pushes up the partition wall 29. Thereby, the ink cavity 4
The ink in 0 is pressurized and ejected from the nozzles 34 and 35 as ink droplets.

As described above, the cut groove 60 is provided at a position facing the cut groove 51 of the piezoelectric plate 45, and air having a lower dielectric constant than the piezoelectric plate 45 exists in the cut groove 60. . Therefore, when a voltage is applied, the electric field goes around the kerf 51 from the tip of the common electrode 47 toward the tip of the individual extraction electrode 53 in the non-active area 57, or from the common electrode 47 to the individual electrode 48 in the non-active area 57. The generation of an electric field (see FIG. 6) in an oblique direction is prevented. As a result, the force for deforming the piezoelectric plate 45 in a direction different from the thickness direction is significantly reduced, and the occurrence of cracks in the piezoelectric plate 45 and the breakage of the common electrode 47 and the individual electrodes 48 are prevented. Further, since the loss of the displacement of the piezoelectric plate 45 in the thickness direction is reduced, the displacement of the piezoelectric plate 45 in the thickness direction can be accurately controlled, and the amount of ink ejected from the nozzles 34 and 35 can be increased. It is possible to control with accuracy.

Further, the partition 40 can be supported by the piezoelectric plate 45 in the non-active area 57, and the wiring structure of the electrodes can be simplified by wiring the electrodes to this portion.

Next, a method for manufacturing the piezoelectric member 30 will be described. FIGS. 5A to 5D show the small-diameter head portion 26 of the ink jet recording head 24 shown in FIGS.
Are shown only partially. Also, in these figures,
The hatched portion indicates a portion where a conductive layer made of a metal film or the like is formed. First, as shown in FIG. 5A, after forming a conductive layer 50 on the entire upper surface of the substrate 32, a cut groove 51 that slightly cuts the substrate 32 is formed transversely by a method such as marking to form the conductive layer 50. Divide. Next, as shown in FIG. 5B, a plate material (piezoelectric plate 62) made of a piezoelectric material and having a cutout groove 60 of a predetermined size provided in advance on the lower surface thereof is fixed to the upper surface of the substrate 32 with a conductive adhesive. At this time, the substrate 32
Is positioned so that the cut groove 60 is opposed to the cut groove 51 provided in. Next, as shown in FIG.
The conductive layer 63 is formed on the upper surface and one side surface of the piezoelectric plate 62 fixed to 2. Thereafter, as shown in FIG. 5D, a plurality of grooves 44 parallel to each other in a direction perpendicular to the cut grooves 51 are formed by a dicing saw 65, and the piezoelectric plate 111 is attached to the plurality of piezoelectric members 30 and the support portions 43. Divide (see FIG. 3). Further, the common electrode 47, the common extraction electrode 52, and the individual extraction electrode 53 are formed by forming the groove 44 so as to cut the substrate 32. Thereafter, the polarization of the piezoelectric plate 45 in the active region 56 shown in FIG. 2 is performed.

As described above, in the present embodiment, the inactive region 5
7 is electrically separated from the piezoelectric plate 45 in the active region 56 by the cut groove 60, so that the electrode wiring (individually) for supplying electricity to the individual electrode 48 provided on the upper surface of the piezoelectric plate 45 is formed. The extraction electrode 53 and the individual conductive layer 54) can be easily formed.

In the second embodiment shown in FIG.
The conductive layer 66 on the upper surface side of the piezoelectric plate 45 is divided by providing a cut groove 60 on the upper surface side of the piezoelectric plate 45, and a portion of the divided conductive layer 66 located in the active region 56 is used as a common electrode 67. In this case, the conductive layer 50 formed on the upper surface of the substrate 32 is
Divide by 1,51. The portion sandwiched between the cut grooves 51, 51 constitutes a common extraction electrode 68, and the common electrode 67 is provided via a common conductive layer 69 provided on the side surface of the piezoelectric plate 45.
Connected to The portions of the conductive layer 50 located outside the cut grooves 51 constitute the individual electrodes 70 and the individual lead lines 71. The method of forming the piezoelectric member 30 of FIG. 6 is the same as that of the first embodiment shown in FIG. 5, but after forming the conductive layer on the upper surface and one end surface of the substrate 32, the cut groove 60 is formed. Are different in forming

The present invention is not limited to the above embodiment, and various modifications are possible. First, the piezoelectric member is not limited to a single-layer type, and may be a stacked type formed by laminating a plurality of thin film piezoelectric sheets so as to alternately sandwich a conductive metal layer. However, in the case of using a stacked type, if all the conductive metal layers are to be cut by the cut grooves, the piezoelectric plate is cut by the cut grooves. Therefore, in the case of the stacked type, it is necessary to leave some conductive metal layers without disconnection, and the effect of separating the active region and the inactive region is higher in the single layer type. In addition, the inkjet recording head of the above-described embodiment includes the large-diameter head portion 25 and the small-diameter head portion 26 having different nozzle orifices as described above, but the present invention includes a nozzle having the same orifice diameter. The present invention can also be applied to an ink jet recording head.

[Brief description of the drawings]

FIG. 1 is a partial front view of an ink jet recording head including a piezoelectric member according to an embodiment of the present invention, as viewed from a nozzle plate side.

FIG. 2 is a sectional view taken along line II-II in FIG.

FIG. 3 is a sectional view taken along line III-III in FIG. 2;

FIG. 4 is an enlarged view of a main part of FIG. 2;

FIGS. 5A to 5D are perspective views for explaining a method of forming a piezoelectric member and a lead electrode.

FIG. 6 is a sectional view showing a second embodiment of the present invention.

FIG. 7 is a cross-sectional view showing a conventional ink jet recording head.

[Explanation of symbols]

Reference Signs List 30 piezoelectric member 32 substrate 40 ink cavity 45 piezoelectric plate 47, 67 common electrode 48, 70 individual electrode 51
Cut grooves 52, 68 ... Common lead electrodes 53, 71 ... Individual lead electrodes 54 ... Individual conductive layers 60 ... Cut grooves 69 ... Common conductive layers

Claims (4)

[Claims] 1. A piezoelectric plate having opposing surfaces, a first electrode and a second electrode provided on the opposing surfaces, respectively, and when a voltage is applied to the electrodes, the piezoelectric member moves in a direction in which the electrodes oppose each other. A piezoelectric member for an ink jet recording head that pressurizes and discharges ink by the deformation, wherein a first electrode provided on one of the opposing surfaces of the piezoelectric plate is formed by a first electrode portion and a second electrode portion. A groove cut into an electrode portion and cut so that the bottom thereof is located inside the piezoelectric plate; and the first or second electrode portion, and the other facing surface of the piezoelectric plate facing these. Wherein the portion of the piezoelectric plate sandwiched between the second electrode and the second electrode is polarized. 2. A piezoelectric plate having a first surface and a second surface facing each other is prepared, and after covering the first surface with a first electrode layer, a first electrode is formed on the first surface. Is divided into a third electrode layer and a fourth electrode layer, and a groove is formed so that the bottom is located inside the piezoelectric plate, while the second surface of the piezoelectric plate is formed. Is coated with a second electrode layer, a voltage is applied to the second electrode layer and the third or fourth electrode layer, and a portion of the piezoelectric plate sandwiched between these electrode layers is polarized to activate the piezoelectric plate. A method for forming a piezoelectric member for an ink jet recording head, comprising forming a region. 3. A substrate having a flat surface is provided, the surface of the substrate is covered with a conductive layer, and the conductive layer is divided into a first electrode portion and a second electrode portion. While forming the groove, a piezoelectric plate having a first surface and a second surface opposed to each other is prepared, and a linear second cut into the first surface of the piezoelectric plate toward the second surface. The first surface of the piezoelectric plate is fixed to the surface of the substrate such that the second groove of the piezoelectric plate and the first groove of the substrate are opposed to each other, and is located on the side opposite to the substrate. After covering the second surface of the piezoelectric plate and the end surface of the piezoelectric plate on the first or second electrode portion side with an electrode layer, the piezoelectric plate is placed in a direction orthogonal to the first and second grooves. A portion divided into a plurality of extending piezoelectric members, sandwiched between the first or second electrode layer and an electrode layer provided on a second surface of the piezoelectric plate facing the first or second electrode layer; Method of forming a piezoelectric member for an ink jet recording head, characterized by forming an active region of the piezoelectric plate is polarized in. 4. A substrate having a flat surface is provided, a surface of the substrate is covered with a conductive layer, and the conductive layer is divided into a first electrode portion and a second electrode portion. While forming the groove, a piezoelectric plate having a first surface and a second surface opposed to each other is prepared, and the first surface of the piezoelectric plate is fixed to the surface of the substrate. The second surface of the piezoelectric plate to be formed and the end surface of the piezoelectric plate on the first or second electrode layer side are covered with an electrode layer, and the electrode layer provided on the first surface of the piezoelectric plate is a third electrode layer. And a fourth electrode layer, and after forming a linear second groove cut so that the bottom is positioned inside the piezoelectric plate, the piezoelectric plate is divided into the first and second grooves. The piezoelectric member is divided into a plurality of piezoelectric members extending in a direction orthogonal to the groove, and the first or second electrode layer and the third or fourth electrode layer of the piezoelectric plate opposed thereto are separated. Method of forming a piezoelectric member for an ink jet recording head is characterized in that the piezoelectric plate of Mareta portion is polarized to form the active region.