JP2002011877A - Actuator unit and ink jet recording head - Google Patents

Abstract

[PROBLEMS] To simplify a manufacturing process and prevent a reduction in the number of effective nozzle openings. A plurality of actuators include a plurality of lower electrode films formed on an elastic film corresponding to a plurality of pressure chambers, a plurality of piezoelectric films formed on the plurality of lower electrode films, A plurality of upper electrode films formed on the piezoelectric film. The plurality of terminals 20 and 21 are provided corresponding to each of the plurality of segment terminals 20 provided corresponding to each of the plurality of upper electrode films and the plurality of lower electrode films classified into several groups. And each of the common terminals 21. The common connection conductor 10 connects the lower electrode films belonging to each group and connects the lower electrode films to the corresponding common terminals 21.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an actuator unit and an ink jet recording head provided with the same, and more particularly, to a method of vibrating an elastic film for sealing an upper opening of a pressure chamber by displacement of a piezoelectric film. The present invention relates to an actuator unit that ejects ink droplets from nozzle openings by changing the pressure of ink in a pressure chamber, and an ink jet recording head.

[0002]

2. Description of the Related Art In general, an ink jet recording head which pressurizes ink in a pressure chamber by a pressure generating means to discharge ink droplets from nozzle openings of a nozzle plate uses a piezoelectric vibrator of a longitudinal vibration mode which expands and contracts in the axial direction. There are a device that uses the piezoelectric vibrator in the flexural vibration mode as a pressure generating device, and a device that uses the piezoelectric vibrator in the flexural vibration mode.

In the former method, the end face of a piezoelectric vibrator is brought into contact with an elastic plate to change the volume of a pressure chamber by the expansion and contraction of the piezoelectric vibrator, so that a recording head suitable for high-density printing can be manufactured. On the other hand, it is necessary to perform a difficult process of cutting the piezoelectric vibrator into a comb-tooth shape in accordance with the arrangement pitch of the nozzle openings, and a work of positioning and fixing the cut piezoelectric vibrator in the pressure chamber, which requires a manufacturing process. There is a problem of complexity.

On the other hand, in the latter case, a piezoelectric vibrator (piezoelectric film) is formed on an elastic film by a relatively simple process of sticking a green sheet of a piezoelectric material according to the shape of the pressure chamber and firing the green sheet. Can be turned on.

FIGS. 10 and 11 are a plan view and a perspective view of an actuator unit of a conventional ink jet recording head having a piezoelectric vibrator (piezoelectric film) in a flexural vibration mode. The actuator unit includes a pair of terminal rows 102 including a plurality of terminals 100 and 101 at a pair of edges facing each other. The terminal 100 is a segment terminal separated from each other, and the terminal 101 is a common terminal. Also, this actuator unit
A communication hole forming substrate 105 (FIG. 12A), which will be described later, is provided. The communication hole forming substrate 105 has a nozzle communication hole array formed by arranging nozzle communication holes 103 communicating with a plurality of nozzle openings in a row. 104 are provided in two rows.

FIG. 12 and FIG. 13 are views showing each layer of the actuator unit shown in FIG. 10 and FIG. FIG. 12A shows a communication hole forming substrate 105, and FIG.
2 (b) shows the pressure chamber forming substrate 106. A plurality of nozzle communication holes 103 communicating with the plurality of nozzle openings are formed on the communication hole forming substrate 105 in two rows, and a plurality of reservoir communication holes 108 communicating with the reservoir are formed in two rows.

A plurality of pressure chambers 109 communicating with the nozzle communication hole 103 and the reservoir communication hole 108 are formed on the pressure chamber forming substrate 106 by the nozzle communication hole 103 and the reservoir communication hole 10.
Two rows are formed corresponding to each of the eight rows. FIG. 12 (c)
As shown in (1), an elastic film 110 is formed on the upper surface of the pressure chamber forming substrate 106, and the upper openings of the plurality of pressure chambers 109 are sealed by the elastic film 110. On the upper surface of the elastic film 110, as shown in FIG. 12D, pedestals 111 for forming terminals are formed on both opposing edges of the pressure chamber forming substrate.

Further, as shown in FIG. 13 (a), a pair of lower electrodes are provided in a predetermined pattern on the upper surface of the elastic film 110 and the upper surface of the pedestal portion 111 so as to pass above the plurality of pressure chambers 109. The film 112 is formed by a printing process using a conductive material such as platinum. FIG. 13 (a)
Reference numeral 113 denotes a pedestal portion that supports a part of the plurality of piezoelectric films 114 described below.

As shown in FIG. 13B, on the upper surface of the lower electrode film 112, a plurality of piezoelectric films 114 are formed corresponding to the plurality of pressure chambers 109 by a printing process. On the upper surface of the plurality of piezoelectric films 114, a plurality of upper electrode films 115 are formed as shown in FIG.

As shown in FIG. 13D, each segment terminal 100 is connected to each upper electrode film 115.
Are formed on the base 111. The pedestal 11
1 on the common terminal 10 connected to the lower electrode film 112.
1 are also formed, and the common terminals 101 located at both ends of each row of the pressure chamber 109 are connected by a terminal extension 116. The upper electrode film 115 at a position corresponding to the common terminal 101 is covered with the terminal extension 116, and the pressure chamber 109 at this position is not used.

[0011]

However, in the above-described conventional recording head, since each of the common terminals 101 is disposed at both ends of the terminal row 102, the distance from one common terminal 101 to the other common terminal 101 is increased. The distance is getting longer. Therefore, if no measures are taken, a voltage drop occurs from one common terminal 101 to the other common terminal 101, and the characteristics of each actuator may become non-uniform. Therefore, conventionally, as shown in FIG. 13D, a high conductivity metal is placed between the common terminals 101 so as to overlap a part of the lower electrode film 112 shown in FIG. (Eg silver)
Are connected by a thick wire terminal extension 116.

As described above, the conventional recording head requires an additional step of forming the terminal extension 116 so as to overlap a part of the lower electrode film 112, which complicates the manufacturing process and increases the manufacturing cost. I was

In a conventional recording head, FIG.
As shown in FIG. 3D, the four upper electrode films 115 located at both ends are covered by the terminal extensions 116, and therefore the piezoelectric films 11 corresponding to these upper electrode films 115 are covered.
4 becomes unusable, and there is a problem that the number of effective nozzle openings decreases.

The present invention has been made in consideration of the above circumstances, and has as its object to simplify the manufacturing process and reduce the number of effective nozzle openings. It is another object of the present invention to provide an actuator unit and an ink jet recording head which can prevent a voltage drop at a common terminal and make the characteristics of a plurality of nozzle openings uniform.

[0015]

In order to solve the above problems, an actuator unit according to the present invention comprises a plurality of pressure chambers respectively communicating with a plurality of nozzle openings, and an elastic film forming one wall surface of the pressure chamber. A plurality of actuators formed on the elastic film corresponding to the plurality of pressure chambers, and a terminal row including a plurality of terminals connected to the plurality of actuators, the plurality of actuators, A plurality of lower electrode films formed on the elastic film corresponding to the plurality of pressure chambers; a plurality of piezoelectric films formed on the plurality of lower electrode films; and a plurality of piezoelectric films formed on the plurality of piezoelectric films. A plurality of upper electrode films, wherein the plurality of terminals include a plurality of segment terminals provided corresponding to each of the plurality of upper electrode films, and a plurality of the plurality of lower electrode films. glue And each common terminal provided corresponding to each group, and connects the lower electrode films belonging to each group and connects the lower electrode film to the corresponding common terminal. It is characterized by further having a common connecting wire.

Preferably, each group includes a pair of the lower electrode films.

[0017] Preferably, the common connection conductor is formed on the same plane as the lower electrode film.

[0018] Preferably, the common communication lead has a portion extending between adjacent actuators.

Preferably, a width of a portion extending between the adjacent actuators is smaller than a width of a partition between the pressure chambers.

[0020] Preferably, the common connecting wire connects the ends of the adjacent lower electrode films on the side closer to the terminal row.

Preferably, the terminal row is formed on each of a pair of opposing edges of the actuator unit.

Preferably, the plurality of pressure chambers have two pressure chambers.
Are formed in rows.

In order to solve the above problems, an ink jet recording head according to the present invention includes any one of the above actuator units and a nozzle plate having the plurality of nozzle openings.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an ink jet recording head according to a first embodiment of the present invention will be described with reference to FIGS.

FIG. 1 is an enlarged longitudinal sectional view showing one actuator and its periphery in the recording head according to the present embodiment. As shown in FIG. 1, this recording head has a nozzle plate having a nozzle opening 1. 2, the flow path forming substrate 3 laminated on the nozzle plate 2, the supply port forming substrate 17 laminated on the flow path forming substrate 3, and the actuator unit 5 laminated on the supply port forming substrate 17. Have.

The actuator unit 5 has a pressure chamber forming substrate 7 in which a pressure chamber 6 is formed. On the upper surface of the pressure chamber forming substrate 7, an elastic film 8 is formed. A lower electrode film 9 and a pedestal film 25 are formed in a predetermined pattern on the upper surface of the elastic film 8, and a piezoelectric film 11 is formed on the upper surface of the lower electrode film 9. An upper electrode film 12 is formed on the upper surface of the piezoelectric film 11, and the upper electrode film 12 is connected to a segment terminal 20. One piezoelectric film 1
One actuator 30 is constituted by one upper electrode film 12 and one lower electrode film 9. Communication hole forming substrate 4 constituting a part of actuator unit 5
Are formed with a plurality of nozzle communication holes 13 and a plurality of reservoir communication holes 14.

The supply port forming substrate 17 has a nozzle communication hole 1
A second nozzle communication hole 18 that communicates with No. 3 and an ink supply port 19 that communicates with the reservoir communication hole 14 are formed. The connection hole 15 communicating with the nozzle opening 1 and the second nozzle communication hole 18 and the ink supply port 1
9 is formed with a reservoir 16 communicating with the reservoir 9. In the reservoir 16, ink supplied to the plurality of pressure chambers 6 is stored. The nozzle communication hole 13 that communicates with the nozzle opening 1 from the pressure chamber 6 and the reservoir communication hole 14 that communicates with the reservoir 16 may have any one of the two holes.

FIGS. 2 and 3 are a plan view and a perspective view of the actuator unit 5 of the recording head according to the present embodiment. The actuator unit 5 includes a pair of terminal rows 22 including a plurality of segment terminals 20 and a plurality of common terminals 21 at a pair of edges facing each other.

FIGS. 4 and 5 are views showing each layer of the actuator unit 5. FIG. 4A shows the communication hole forming substrate 4, and FIG. 4B shows the pressure chamber forming substrate 7 laminated on the communication hole forming substrate 4. Two rows of nozzle communication holes 13 are formed in the communication hole forming substrate 4 corresponding to the two rows of nozzle openings 1.
A row of reservoir communication holes 14 is formed.

On the other hand, a plurality of pressure chambers 6 communicating with the nozzle communication holes 13 and the reservoir communication holes 14 are formed in the pressure chamber forming substrate 7 in two rows corresponding to each row of the nozzle communication holes 13 and the reservoir communication holes 14. Is formed. As shown in FIG. 4C, an elastic film (diaphragm) 8 is formed on the upper surface of the pressure chamber forming substrate 7, and the elastic film 8 forms a plurality of pressure chambers 6.
Is sealed at the top surface. On the upper surface of the elastic film 8, pedestals 24 for forming terminals are formed at both edges of the actuator unit 5, as shown in FIG.

Further, as shown in FIG. 5A, on the upper surface of the elastic film 8, a plurality of lower electrode films 9 formed corresponding to the plurality of pressure chambers 6 and adjacent lower electrode films 9 are formed. And a substantially T-shaped common connecting lead 10 for connecting the lower electrode film 9 to the corresponding common terminal 21 (see FIG. 2) by a printing process using a conductive material such as platinum. . The lower electrode film 9 and the common connection lead 10 are formed at the same time by printing before forming the piezoelectric film 11 at least. A part of the common communication lead wire 10 is constituted by a thin wire portion 10a extending between the actuators 60. The line width of the thin line portion 10 a is smaller than the width of the partition wall between the pressure chambers 6. In FIG. 5A, reference numeral 25 denotes a pedestal film that supports a part of the piezoelectric film 11.

As shown in FIG. 5B, a plurality of piezoelectric films 11 are formed on the upper surfaces of the plurality of lower electrode films 9 by a printing process. As shown in FIG.
As shown in (c), a plurality of upper electrode films 12 are formed.

As shown in FIG. 5D, on the pedestal portion 24, each segment terminal 20 connected to each upper electrode film 12, and each common terminal 2 connected to each thin wire portion 10a.
1 are formed. As described above, in the present embodiment, a pair of adjacent lower electrode films 9 is regarded as one group, and each common terminal 21 is provided corresponding to each group.

As described above, according to the ink jet recording head of this embodiment, the plurality of lower electrode films 9 are classified into several groups, and the common terminals 21 are provided corresponding to each group. The length of the common connecting wire 10 is shortened, and the problem of voltage drop is eliminated. For this reason, it is possible to make the characteristics of the plurality of nozzle openings uniform without forming a thick line made of silver or the like on the common connecting lead 10 so as to simplify the manufacturing process of the recording head. In addition, since the upper electrode films 12 at both ends are not disabled, the number of effective nozzle openings is not reduced.

Further, since the common connecting conductor 10 is formed simultaneously on the same plane as the lower electrode film 9 before the piezoelectric film 11 is formed, it is necessary to print a narrow gap between the piezoelectric films 11. And the printing process becomes easier.

Next, an ink jet recording head according to a second embodiment of the present invention will be described with reference to FIGS. Note that the present embodiment is a modification of the configuration of the common connection conductor in the first embodiment described above.
In the following, a description will be given focusing on portions different from the first embodiment.

FIGS. 6 and 7 are a plan view and a perspective view of the actuator unit 35 of the recording head according to the present embodiment. FIGS. 8 and 9 are diagrams showing each layer of the actuator unit 35. FIG.

As shown in FIG. 6 and FIG. 7, the point that the common terminals 21 are provided for each group of a pair of adjacent actuator units 70 is the same as in the first embodiment. Further, as shown in FIGS. 8A to 8D, the configurations of the communication hole forming substrate 4 and the pressure chamber forming substrate 7 are the same as those in the first embodiment, and the upper surface of the pressure chamber forming substrate 7 has an elasticity. The point that the film 8 is formed and the pedestal portion 24 is formed thereon is also common to the first embodiment.

In this embodiment, FIG.
As shown in (a), the common connection lead 30 is connected to the terminal row 2
2 (see FIG. 6), the ends of adjacent lower electrode films 9 are connected to each other. Unlike the first embodiment, the common connection lead 30 is not formed between the actuators 70.

As shown in FIGS. 9B to 9D, the piezoelectric film 11, the upper electrode film 12, and the segment terminals 20 are formed.
The configuration of each of the common terminal 21 and the common terminal 21 is the same as that of the first embodiment.

According to the present embodiment, the same effects as those of the first embodiment can be obtained, and it is not necessary to extend a thin conductive wire between the actuators 70, so that requirements for printing accuracy are eased.

[0042]

As described above, according to the present invention, since a plurality of lower electrode films are classified into several groups and each common terminal is provided corresponding to each group, the lower electrode films are connected to each other. Thus, the total length of the common connecting wire is shortened, and the problem of voltage drop is eliminated. For this reason, it is possible to make the characteristics of the plurality of nozzle openings uniform without forming a thick line made of silver or the like on the common connecting lead wire, thereby simplifying the manufacturing process. Since the upper electrode films at both ends are not unusable, the number of effective nozzle openings is not reduced.

[Brief description of the drawings]

FIG. 1 is an enlarged longitudinal sectional view showing one actuator and its periphery in an ink jet recording head according to a first embodiment of the present invention.

FIG. 2 is a plan view of an actuator unit of the inkjet recording head according to the first embodiment of the present invention.

FIG. 3 is a perspective view of an actuator unit of the ink jet recording head according to the first embodiment of the present invention.

FIG. 4 is a plan view showing each layer of the actuator unit of the ink jet recording head according to the first embodiment of the present invention.

FIG. 5 is a plan view showing each layer of the actuator unit of the inkjet recording head according to the first embodiment of the present invention.

FIG. 6 is a plan view of an actuator unit of an inkjet recording head according to a second embodiment of the present invention.

FIG. 7 is a perspective view of an actuator unit of an inkjet recording head according to a second embodiment of the present invention.

FIG. 8 is a plan view showing each layer of an actuator unit of an ink jet recording head according to a second embodiment of the present invention.

FIG. 9 is a plan view showing each layer of an actuator unit of an ink jet recording head according to a second embodiment of the present invention.

FIG. 10 is a plan view of an actuator unit of a conventional ink jet recording head.

FIG. 11 is a perspective view of an actuator unit of a conventional ink jet recording head.

FIG. 12 is a plan view showing each layer of an actuator unit of a conventional ink jet recording head.

FIG. 13 is a plan view showing each layer of an actuator unit of a conventional ink jet recording head.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Nozzle opening 2 Nozzle plate 3 Flow path forming substrate 4 Communication hole forming substrate 5, 35 Actuator unit 6 Pressure chamber 7 Pressure chamber forming substrate 8 Elastic film 9 Lower electrode film 10, 30 Common connection lead 10a Thin portion of common connection lead 11 Piezoelectric film 12 Upper electrode film 13 Nozzle communication hole 14 Reservoir communication hole 15 Connection hole 16 Reservoir 17 Supply port forming substrate 18 Second nozzle communication hole 19 Ink supply port 20 Segment terminal 21 Common terminal 22 Terminal row 60, 70 Actuator

Claims (9)

[Claims] A plurality of pressure chambers respectively communicating with the plurality of nozzle openings; an elastic film forming one wall surface of the pressure chamber; and a plurality of pressure chambers formed on the elastic film corresponding to the plurality of pressure chambers. And a terminal row composed of a plurality of terminals connected to the plurality of actuators, wherein the plurality of actuators have a plurality of lower portions formed on the elastic film corresponding to the plurality of pressure chambers. An electrode film, a plurality of piezoelectric films formed on the plurality of lower electrode films,
A plurality of upper electrode films formed on the plurality of piezoelectric films, the plurality of terminals are provided with a plurality of segment terminals provided corresponding to each of the plurality of upper electrode films, and A plurality of lower electrode films that are classified into several groups, and each common terminal is provided corresponding to each of the groups. The actuator unit according to claim 1, further comprising a common connecting wire connecting the lower electrode film to a common terminal. 2. The actuator unit according to claim 1, wherein each of said groups includes a pair of said lower electrode films. 3. The device according to claim 1, wherein the common connection lead is formed on the same plane as the lower electrode film.
Or the actuator unit according to 2. 4. The actuator unit according to claim 3, wherein the common communication lead has a portion extending between adjacent actuators. 5. The actuator unit according to claim 4, wherein a width of a portion extending between the adjacent actuators is smaller than a width of a partition wall between the pressure chambers. 6. The semiconductor device according to claim 1, wherein the common connection conductor connects ends of the adjacent lower electrode films on a side near the terminal row. The actuator unit as described. 7. The actuator unit according to claim 1, wherein the terminal row is formed on each of a pair of opposing edges of the actuator unit. 8. The actuator unit according to claim 1, wherein the plurality of pressure chambers are formed in two rows. 9. An ink jet recording head comprising: the actuator unit according to claim 1; and a nozzle plate in which the plurality of nozzle openings are formed.