JPH09314830A - Ink jet recording head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To lower capacitance and enhance heat generation of an elastic membrane and reduce the load on an outer part drive circuit by a method wherein an elastic membrane which pressurizes an ink in a pressure generation chamber and a piezoelectric body membrane which deforms the elastic membrane are provided and the thickness of the piezoelectric body membrane of a wiring area is formed thicker than the area opposing to the pressure generation chamber. SOLUTION: An ink pressure generation chamber base plate 1 which is constituted by etching a silicon simple crystal base plate is determined one surface to an aperture surface 9 and a rear surface is provided with two or more series of pressure generation chambers 3..., 4... and a reservoirs 5, 6 supplying an ink with these pressure generation chambers so form an elastic membrane 2. Then, a nozzle plate 12 which is set punched nozzle apertures 10, 11 to communicate at an end side of the pressure generation chambers 3, 4 is fixed. A lower electrode 13 is laminated with the piezoelectric body membrane 14 on a surface of the elastic membrane 2 and at this time, the piezoelectric body membrane 14 is provided with piezoelectric vibration areas 14a, 14b and a wiring area forming a wiring pattern at a periphery thereof, and forms the wiring area thicker than the piezoelectric vibration areas 14a, 14b.

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 which expands and contracts a part of a pressure generating chamber communicating with a nozzle opening by an actuator which bends and vibrates to discharge ink droplets from the nozzle opening.

[0002]

2. Description of the Related Art An ink jet recording head has a piezoelectric vibration type in which a pressure generating chamber is mechanically deformed to pressurize ink, and a heating element is provided in the pressure generating chamber, and bubbles generated by heat of the heating element are provided. And a bubble jet type in which the ink is pressurized by the pressure of the above. The recording head of the piezoelectric vibration type is further classified into two types, a first recording head using a piezoelectric vibrator displaced in the axial direction, and a second recording head using a piezoelectric vibrator displaced in a bending direction. . The first recording head is capable of high-speed driving and high-density recording. On the other hand, when the piezoelectric vibrator is processed with a cutting operation, or when the piezoelectric vibrator is fixed to the pressure generating chamber, the first recording head needs to perform three operations. There is a problem that a dimensional assembly operation is required and the number of manufacturing steps is increased.

On the other hand, since the piezoelectric vibrator is formed as a film in the second recording head, the second recording head can be manufactured by firing integrally with the elastic film forming the pressure generating chamber. Although it has a feature that the process can be simplified, an insulating layer and a normal piezoelectric vibrator are formed on the surface of the elastic film because the piezoelectric vibrator and the connection terminal for connecting to an external circuit are connected in a plane. It is necessary to form a connection pattern via the piezoelectric film.

[0004]

The piezoelectric vibrator thus formed on the elastic film is formed by applying a film forming technique such as sputtering to a piezoelectric material. Since the thickness is extremely thin compared to the case of sticking and forming, the electrostatic capacitance becomes large, and accordingly, the heat generation of the elastic film due to the increase of the dielectric loss in the connection pattern area and the driving circuit. There is a problem such as an increase in current capacity. The present invention has been made in view of such a problem, and its object is to reduce the capacitance from the connection terminal that receives a signal from the external drive circuit to the piezoelectric vibration region as much as possible. Another object of the present invention is to provide an ink jet recording head capable of reducing the heat generation of the elastic film and the load of the external drive circuit.

[0005]

In order to solve such a problem, in the present invention, a nozzle plate having a plurality of nozzle openings formed therein, a reservoir for receiving ink from the outside, and the reservoir and the ink supply. A flow path forming substrate having a plurality of pressure generating chambers connected to each other through the mouth and communicating with each of the nozzle openings, an elastic film for pressurizing ink in the pressure generating chambers, and the pressure generating chambers facing each other. In an ink jet head including a piezoelectric film that is disposed at a position and flexibly deforms the elastic film, the piezoelectric film is formed on the surface of the elastic film from the pressure generating chamber to the wiring region, and the piezoelectric film of the wiring region is formed. The thickness of the piezoelectric film was made thicker than the region facing the pressure generating chamber, and the metal layer for wiring was formed there.

[0006]

Since the thickness of the metal layer and the lower electrode in the wiring region is larger than that in the piezoelectric vibration region, the capacitance in the wiring region is small.

[0007]

1 and 2 each show an embodiment of the present invention, in which reference numeral 1 is an ink pressure generating chamber substrate formed by etching a silicon single crystal substrate. The pressure generating chambers 3, 3, ..., 4, 4, ... Are arranged in a plurality of rows so that the elastic film 2 is formed on the back surface and one surface is an opening surface 9. Reservoirs 5 and 6 for supplying ink to the chambers, and ink supply ports 7 and 8 for communicating these pressure generating chambers 3 and 4 and the reservoirs 5 and 6 with a constant fluid resistance are formed.

A nozzle plate 12 having nozzle openings 10 and 11 is fixed to the opening surface 9 side so as to communicate with one end sides of the pressure generating chambers 3 and 4.

On the other hand, a lower electrode 13 made of a metal layer is formed on the surface of the elastic film 2, and a piezoelectric film 14 is attached to the surface of the lower electrode 13 by a film forming method. As shown in FIG. 3, the piezoelectric film 14 faces the pressure generating chambers 3 and 4, and expands and contracts the pressure generating chambers 3 and 4.
b, and wiring regions 14c and 14 forming wiring patterns for supplying drive signals to the piezoelectric vibrating regions 14a and 14b.
In order to form d and d, the wiring regions 14c and 14d are formed to be thicker than the piezoelectric vibration regions 14a and 14b and face the pressure generating chambers 3 and 4 as shown in FIG. It is divided into strips.

For the piezoelectric film 14 having such two types of thickness regions, the film formation time is controlled by using a mask or the like at the time of film formation, or after the whole is formed to the thickness of the wiring regions 14c and 14d, The piezoelectric vibrating regions 14a and 14b can be easily manufactured by a method such as etching and thinning.

FIG. 5 is an enlarged view of the above-mentioned piezoelectric film 14, and flexural vibration is possible to the extent that the piezoelectric vibration regions 14a and 14b can expand and contract the pressure generating chambers 3 and 4. Is formed to a thickness of about 1 μm, and the wiring regions 14c and 14d are formed in the piezoelectric vibration region 1.
The metal layer is formed to a thickness such that the metal layer can be formed without causing disconnection or the like with the upper electrodes 15 and 16 formed on the surfaces of 4a and 14b, for example, about 5 μm.

Slopes 14e and 14f are formed at the boundary between these two regions so as not to form abrupt steps, and the slopes 14e and 14f are routed from the ends of the upper electrodes 15 and 16 to the ends. Wiring region 14 of piezoelectric film 14
metal layers 17 and 18 forming a wiring pattern on c and 14d
Are formed.

Referring back to FIGS. 1 and 2, the ink pressure generating chamber substrate 1 and the nozzle plate 12 are integrally fixed so as to be liquid-tight and support the peripheral portion and the central portion.
The recording head is housed in a holder 19 provided with a. The wiring regions 14c and 14d of the piezoelectric film 14 are
It is connected to an external drive circuit via a flexible cable 20.

In this embodiment, when a drive signal is supplied from the flexible cable 20, the drive signal is applied to the piezoelectric vibrating regions 14a and 14b through the metal layers 17 and 18 of the wiring regions 14c and 14d of the piezoelectric film 14. .

As a result, the piezoelectric vibrating regions 14a and 14b receive an electric field between the piezoelectric vibrating regions 14a and 14b to cause flexural vibration to expand the pressure generating chambers 3 and 4, thereby causing the inks in the reservoirs 5 and 6 to move. 4, and then the pressure generating chamber 3,
4 is contracted to eject ink droplets from the nozzle openings 10 and 11.

By the way, the wiring regions 14c and 14d formed in the non-vibrating region of the piezoelectric film 14 are the piezoelectric vibrating region 14
Since it is thicker than a and 14b, the electrostatic capacity formed by the lower electrode 13 and the wiring metal layers 17 and 18 becomes extremely small. As a result, the current for charging the electrostatic capacitance formed in the wiring region becomes small, so that the wiring region 1
The amount of heat generated in 4c and 14d is small, the required current value is small, and the loss in the wiring pattern of the flexible cable 20 is small.

Although the elastic film 2 and the lower electrode 13 are formed as separate members in the above embodiment, the elastic film 2
When is made of a metal such as platinum, the elastic film can be used as the lower electrode.

[0018]

As described above, in the present invention,
A flow including a nozzle plate having a plurality of nozzle openings, a reservoir for receiving ink supply from the outside, and a plurality of pressure generating chambers connected to the reservoir via ink supply ports and communicating with each of the nozzle openings. In an ink jet head including a channel forming substrate, an elastic film that pressurizes ink in the pressure generating chamber, and a piezoelectric film that is disposed at a position facing the pressure generating chamber and flexibly deforms the elastic film, the surface of the elastic film is pressed. The piezoelectric film is formed from the generation chamber to the wiring region, and the thickness of the piezoelectric film in the wiring region is made thicker than the region facing the pressure generation chamber, and the metal layer for wiring is formed here. Since the thickness of the metal layer and the lower electrode is larger than the piezoelectric vibration area, the capacitance of the wiring area can be reduced, and the piezoelectric loss and the charging current can be reduced. That.

[Brief description of drawings]

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

FIG. 2 is a sectional view showing one embodiment of the present invention.

FIG. 3 is a perspective view showing an example of the piezoelectric film of the recording head.

FIG. 4 is a perspective view showing a state in which a piezoelectric film is cut out in accordance with a pressure generating chamber.

FIG. 5 is an enlarged sectional view showing a piezoelectric film.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Ink pressure generation chamber substrate 2 Elastic film 3, 4 Pressure generation chamber 5, 6 Reservoir 7, 8 Ink supply port 7, 8 10, 11 Nozzle opening 13 Lower electrode 13 14 Piezoelectric film 14a, 14b Piezoelectric vibration region 14c, 14d Wiring area 14e, 14f Slope portion 15, 16 Upper electrode 20 Flexible cable

Claims (2)

[Claims] 1. A nozzle plate having a plurality of nozzle openings, a reservoir for supplying ink from the outside, and a plurality of pressures connected to the reservoir via the ink supply port and communicating with each of the nozzle openings. A flow path forming substrate having a generation chamber, an elastic film that pressurizes ink in the pressure generation chamber, and a piezoelectric film that is disposed at a position facing the pressure generation chamber and flexibly deforms the elastic film. In the inkjet head, the piezoelectric film is formed on the surface of the elastic film from the pressure generating chamber to the wiring region, and the thickness of the piezoelectric film in the wiring region is thicker than a region facing the pressure generating chamber. An ink jet recording head having a metal layer for wiring formed thereon. 2. A sloped surface portion is formed on the piezoelectric film near the boundary between the wiring region and the pressure generating chamber.
3. The ink jet recording head according to item 1.