JPH0848032A - Piezoelectric driving element and ink jet recording head using the same - Google Patents

Abstract

PURPOSE:To enhance displacement efficiency while enabling high speed driving by alternately forming conductive layers to have different polarities and piezoelectric material layers at the central part thereof to constitute a first layer and forming a second layer on one surface of the first layer. CONSTITUTION:An ink jet recording head is constituted by laminating a nozzle plate 3 having nozzle orifices 2 bored therein, a passage forming plate 5 forming a pressure generation chamber 4 and an elastic plate 6 deformed by the displacement of a piezoelectric driving element 10. In this case, the piezoelectric driving element 10 is constituted by forming first and second layers 11, 12 and the first layer 11 is constituted by forming conductive layers 13, 13 to serve as one electrodes extending from one end of the first layer to the central part thereof and conductive layer 14, 14 to serve as other electrodes extending from the other end of the first layer to central part thereof so as to hold piezoelectric material layers 15, 15 between the conductive layers to provide the overlapped part 16 of the conductive layers 13, 14 at the central part. By this constitution, only the central part is deformed to apply large mechanical energy to the elastomer 6 as the element to be driven brought into contact with the central part.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piezoelectric driving body in which piezoelectric materials and conductive layers are alternately laminated, and an ink jet recording head using the same.

[0002]

2. Description of the Related Art For example, an ink jet recording head which forms a part of a pressure generating chamber communicating with a nozzle opening and a reservoir with an elastic plate, and elastically deforms the elastic plate to expand and contract the pressure generating chamber. As a drive source for small devices, a flexural vibration mode piezoelectric drive that deforms in the plane direction, and a longitudinal vibration mode piezoelectric drive that produces axial displacement by alternately stacking piezoelectric materials and conductive materials are used. ing. The former has a simple structure and can be manufactured relatively inexpensively, but has a problem that the generated force is small and the response frequency is low, while the latter can be driven at high speed, but the displacement amount is small. There is.

[0003]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to provide a small piezoelectric device which can be driven at a high speed and can obtain a large displacement amount. To provide a driver.

[0004]

In order to solve such a problem, in the present invention, a first layer is formed by alternately laminating conductive layers having different poles with a piezoelectric material so as to overlap in the central portion. And a second layer formed on one surface of the first layer.
It is made up of layers.

[0005]

When a drive signal is applied to the first layer, the layer contracts and strain occurs between both layers, and since both ends are fixed to the base, only the central portion is deformed. A large amount of mechanical energy is applied to the driven body that is in contact therewith.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the present invention will be described below with reference to the illustrated embodiments. FIG. 1 shows the ink jet recording head to which the piezoelectric driving body of the present invention is applied. Reference numeral 1 in the drawing is a flow path constituting unit constituting the ink jet recording head, and a nozzle plate having a nozzle opening 2 formed therein. 3, a flow path forming plate 5 that forms the pressure generating chamber 4, and an elastic plate 6 that is deformed by the displacement of a piezoelectric driving body 10 described later are laminated.

Reference numeral 10 denotes a piezoelectric driving body which is a feature of the present invention, and is constituted by laminating a first layer 11 and a second layer 12, and the first layer 11 is formed from one end to a central portion. A plurality of conductive layers 13 and 13 serving as one electrode extending from the other end, and conductive layers 14 and 14 serving as the other electrode extending from the other end to the central portion are formed so as to sandwich the piezoelectric material layers 15 and 15. It is configured such that an overlapping portion 16 of the conductive layers 14 and 15 is formed in the portion.

The second layer 12 is made of a material having a strong bonding force with respect to the first layer 11, for example, a ceramic thin plate,
Further, the same material as the first layer 11 which is not affected by the electric field is used.

In this piezoelectric driving body 10, a step of forming a conductive layer on a green sheet of a piezoelectric material and laminating the green sheet of the piezoelectric material on the surface of the conductive layer is repeated a plurality of times to obtain a first layer having a predetermined thickness. 11 is formed. Then, a green sheet of ceramics or the above piezoelectric material is laminated on one surface of the first layer to a required thickness, and both layers are fired to easily manufacture the first sheet.

When manufactured by such a method, it is possible to easily obtain the long piezoelectric driving body 23 as shown in FIG. 3. Therefore, both sides of the piezoelectric driving body 23 are fixed to the base 20, and each pressure generating chamber is fixed. By dicing at a predetermined pitch with a dicing saw, a wire saw 22 or the like so as to correspond to, it is possible to obtain a size suitable for the non-driving body. Then, by fixing the driven body, that is, the elastic plate 6 of the flow path forming unit 1 in this embodiment, to the surface of each drive body 10, the target device is completed.

In this embodiment, when a driving signal is applied to the piezoelectric driving body 10, the first layer 11 becomes the conductive layers 13 and 1.
The overlapping portion 16 of 4 contracts in the axial direction by the d31 effect. However, since the second layer 12 that is not deformed by the piezoelectric effect is fixed to the surface of the first layer 11,
The first layer 11 with both ends fixed to the base 20 as fixed points,
The second layer 12 is deformed so that the central portion is convex as shown in FIG. Of course, since both ends are fixed to the base 20 having a large rigidity, an extremely large force is generated.

This deformation of the piezoelectric driver 10 deforms the central portion of the elastic plate 6 to compress the pressure generating chamber 4, and this ink is compressed to eject an ink droplet from the nozzle opening 2. .

When the drive signal is removed, the first layer 11 returns to its original state, so that the entire drive body also becomes flat and the pressure generating chamber 4 expands, and ink flows from the reservoir into the pressure generating chamber 4. The next ink droplet can be ejected.

The first layer 11 has a thickness of 0.1 mm (5 layers of piezoelectric material having a thickness of 20 μm are laminated with the conductive layers 13 and 14 sandwiched therebetween), a length of 1 mm, and a length L of the overlapping portion 16 of the conductive layers =
A piezoelectric driving body having a thickness of 0.6 mm, a second layer 12 having a thickness of 0.1 mm and a length of 1 mm was manufactured and investigated.
A displacement of 5 μm could be obtained.

On the other hand, for comparison, as shown in FIG. 4, the piezoelectric material 32 and the conductive materials 30 and 31 are alternately laminated, and the piezoelectric driving body 33 utilizing displacement in the direction orthogonal to the laminating direction of the conductive layers. Then, in order to obtain the same degree of displacement, a length of about 6 mm was required. From these, the piezoelectric driving body of the present invention can be used as an actuator which is extremely suitable for driving a small device.

In particular, since the central portion of the piezoelectric driving member can be selectively deformed, it is an optimum actuator for an ink jet type recording head which requires intensive deformation of the central portion of the pressure generating chamber 4.

[0017]

As described above, according to the present invention, the first layer is formed by alternately laminating the piezoelectric material so that the conductive layers serving as different poles overlap each other in the central portion, and the first layer and the first layer. Since the second layer is formed on one surface, when a drive signal is applied to the first layer, this layer contracts, so that distortion occurs between the two layers to cause bending, and the layer is abutted on the surface. It is possible to apply mechanical energy to the driven body which is present, and since it is a displacement in the direction parallel to and perpendicular to the conductive layer, high speed driving is possible. Further, since both ends of the piezoelectric driving body are fixed to the base, it is possible to extremely reduce the damage during the assembly work as compared with the case where the piezoelectric driving body is supported in a cantilever shape.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an example of applying a piezoelectric driving body of the present invention to an ink jet recording head.

FIG. 2 is a diagram showing an operation of the above apparatus.

FIG. 3 is a diagram showing an example of a method of manufacturing a piezoelectric driver.

FIG. 4 is a diagram showing an example of a conventional piezoelectric driving body used in an ink jet recording head.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Flow path constituent unit 2 Nozzle opening 3 Nozzle plate 4 Pressure generating chamber 5 Flow path forming plate 6 Elastic plate 10 Piezoelectric driver 11 First layer 12 Second layer 13, 14 Conductive layer 15 Piezoelectric material layer 16 Overlapping part 20 Base

Claims (4)

[Claims] 1. A first layer formed by alternately laminating conductive layers serving as different poles with a piezoelectric material so as to form an overlapping portion at a central portion, and fixed to one surface of the first layer. Second
And a piezoelectric driving body. 2. The piezoelectric driving body according to claim 1, wherein the second layer is made of ceramic or the piezoelectric material. 3. A nozzle plate having a nozzle opening, a flow path forming plate forming a pressure generating chamber and a reservoir,
A flow path forming unit formed by laminating elastic plates respectively; a first layer formed by alternately laminating conductive layers serving as different poles with a piezoelectric material so as to form an overlapping portion at a central portion; An ink jet recording head, comprising a piezoelectric driving body formed of a second layer formed on one surface of the one surface, and fixed so that at least an overlapping portion of the conductive layers contacts the elastic plate. 4. The ink jet recording head according to claim 3, wherein the second layer is made of ceramic or the piezoelectric material.