JP3844188B2 - Actuator unit and ink jet recording head - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an actuator unit and an ink jet recording head including the unit, and in particular, an elastic film that seals an upper surface opening of a pressure chamber is vibrated by a displacement of a piezoelectric film, whereby the pressure of ink in the pressure chamber is increased. The present invention relates to an actuator unit and an ink jet recording head that discharge ink droplets from nozzle openings by changing the angle.
[0002]
[Prior art]
In general, as an ink jet recording head that pressurizes ink in a pressure chamber by pressure generating means and ejects ink droplets from nozzle openings of a nozzle plate, a piezoelectric vibrator in a longitudinal vibration mode that expands and contracts in the axial direction is used as pressure generating means. Some of them use a piezoelectric vibrator in a flexural vibration mode as a pressure generating means.
[0003]
In the former, the end face of the piezoelectric vibrator is brought into contact with the elastic plate and the volume of the pressure chamber is changed by the expansion / contraction operation of the piezoelectric vibrator. On the other hand, a recording head suitable for high-density printing can be manufactured, The manufacturing process is complicated because it requires a difficult process of dividing the piezoelectric vibrator into a comb-teeth shape in accordance with the arrangement pitch of the nozzle openings, and an operation for positioning and fixing the separated piezoelectric vibrator in the pressure chamber. There is a problem.
[0004]
On the other hand, in the latter case, a piezoelectric vibrator (piezoelectric film) can be formed on the elastic film by a relatively simple process of attaching a green sheet of piezoelectric material in accordance with the shape of the pressure chamber and firing the sheet. it can.
[0005]
11 and 12 are a plan view and a perspective view of an actuator unit of a conventional ink jet recording head provided with a piezoelectric vibrator (piezoelectric film) in a flexural vibration mode. This 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. In addition, this actuator unit includes two rows of nozzle communication hole rows 104 formed by arranging nozzle communication holes 103 communicating with a plurality of nozzle openings in rows.
[0006]
[Problems to be solved by the invention]
In the conventional recording head described above, a plurality of terminals including the segment terminal 100 and the common terminal 101 are all arranged at a uniform interval. That is, the interval between the common terminals 101 arranged at both ends of the terminal row 102 and the segment terminals 100 adjacent to the common terminals 101 is set to be the same as the interval between the segment terminals 100.
[0007]
However, since a considerable potential difference exists between the segment terminal 100 and the common terminal 101, if a short circuit occurs between the two terminals, a large current flows, which is dangerous. In general, silver is used to form the common terminal 101. However, since silver has a high ionization tendency, silver is ionized due to a potential difference between the segment terminal 100 and the common terminal 101, and migration occurs. Then, there is a risk that both terminals are electrically connected and short-circuited. In addition, the segment terminal 100 and the common terminal 101 may be erroneously connected during the soldering operation during the recording head mounting process.
[0008]
In particular, in order to meet the recent demand for higher printing density, the interval between the terminals of the recording head is becoming narrower, so the problem of short circuit between the segment terminal 100 and the common terminal 101 is serious. It has become.
[0009]
The present invention has been made in consideration of the above-described circumstances, and an object thereof is to provide an actuator unit and an ink jet recording head that can prevent a short-circuit between a segment terminal and a common terminal. For the purpose.
[0010]
[Means for Solving the Problems]
In order to solve the above problems, an actuator unit according to the present invention corresponds to a plurality of pressure chambers respectively communicating with a plurality of nozzle openings, an elastic membrane constituting one wall surface of the pressure chamber, and the plurality of pressure chambers. A plurality of actuators formed on the elastic film, and a terminal row composed of a plurality of terminals connected to the plurality of actuators, the plurality of actuators corresponding to the plurality of pressure chambers A plurality of lower electrode films formed on the elastic 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; And the plurality of terminals are shared by a plurality of segment terminals provided corresponding to each of the plurality of upper electrode films, and at least one shared by all or a part of the plurality of lower electrode films. A common terminal and an interval between the common terminal and the segment terminal adjacent to the common terminal are wider than an interval between the segment terminals adjacent to each other, and the segment terminal and the common terminal are connected to the terminal row. The widths measured along the longitudinal direction are aligned, and the intervals between the segment terminals are uniform.
[0012]
Preferably, the plurality of lower electrode films are classified into several groups, the common terminals are provided corresponding to the groups, and the lower electrode films belonging to the groups are connected to each other. Further, each of the common connection conductors connecting the lower electrode film to the common terminal is provided.
[0013]
Preferably, a pair of the lower electrode films belong to each group.
[0014]
Preferably, the common connecting conductor is formed on the same plane as the lower electrode film, and has a portion extending through the actuators adjacent to each other.
[0015]
Preferably, the common connection conducting wire connects ends of the lower electrode films adjacent to each other on the side close to the terminal row.
[0016]
Preferably, the plurality of actuators are formed in a plurality of rows, a terminal row composed of the plurality of terminals is formed in one row, and all the rows of the actuators in a plurality of rows are formed in a single terminal row. It is connected.
[0017]
Preferably, the single terminal row is formed at one edge of the actuator unit.
[0018]
Preferably, the plurality of actuators are formed in a plurality of rows, a plurality of terminal rows each including the plurality of terminals are formed, and at least one of the plurality of rows of the terminal rows includes a plurality of rows. At least two of the actuators are connected.
[0019]
Preferably, a plurality of the terminal rows are formed at a pair of edges of the actuator unit facing each other.
[0020]
Preferably, at least one of the plurality of terminal rows is arranged between the actuator rows and is connected to both of the pair of actuator rows located on both sides thereof.
[0021]
In order to solve the above problems, an ink jet recording head according to the present invention includes any one of the actuator units described above and a nozzle plate in which the plurality of nozzle openings are formed.
[0022]
DETAILED DESCRIPTION OF THE INVENTION
The ink jet recording head according to the first embodiment of the present invention will be described below with reference to FIGS.
[0023]
FIG. 1 is an enlarged longitudinal sectional view showing one actuator and its periphery in a recording head according to the present embodiment. As shown in FIG. 1, this recording head includes a nozzle plate 2 having nozzle openings 1, A flow path forming substrate 3 stacked on the nozzle plate 2, a supply port forming substrate 17 stacked on the flow path forming substrate 3, and an actuator unit 5 stacked on the supply port forming substrate 17 are provided. .
[0024]
The actuator unit 5 has a pressure chamber forming substrate 7 in which a pressure chamber 6 is formed, and an elastic film 8 is formed on the upper surface of the pressure chamber forming substrate 7. A lower electrode film 9 and a pedestal film 25 are formed 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 the segment terminal 20. One actuator 30 is constituted by one piezoelectric film 11, one upper electrode film 12, and one lower electrode film 9. A plurality of nozzle communication holes 13 and a plurality of reservoir communication holes 14 are formed in the communication hole forming substrate 4 constituting a part of the actuator unit 5.
[0025]
The supply port forming substrate 17 is formed with a second nozzle communication hole 18 that communicates with the nozzle communication hole 13 and an ink supply port 19 that communicates with the reservoir communication hole 14. In the flow path forming substrate 3, a connection hole 15 communicating with the nozzle opening 1 and the second nozzle communication hole 18 and a reservoir 16 communicating with the ink supply port 19 are formed. The reservoir 16 stores ink supplied to the plurality of pressure chambers 6. In addition, the nozzle communication hole 13 communicating from the pressure chamber 6 to the nozzle opening 1 and the reservoir communication hole 14 communicating with the reservoir 16 may be any one of the two holes.
[0026]
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 on a pair of edges facing each other. Further, two rows of nozzle communication hole rows 23 formed by arranging a plurality of nozzle communication holes 13 communicating with the plurality of nozzle openings 1 in a row are formed.
[0027]
4 and 5 are diagrams showing each layer of the actuator unit shown in FIGS. 1 to 3. 4A shows the communication hole forming substrate 4, and FIG. 4B shows the pressure chamber forming substrate 7. In the communication hole forming substrate 4, a plurality of nozzle communication holes 13 communicating with the plurality of nozzle openings 1 are formed in two rows, and a plurality of reservoir communication holes 14 communicating with the reservoir 16 are formed in two rows. In the pressure chamber forming substrate 7, a plurality of pressure chambers 6 communicating with the nozzle communication holes 13 and the reservoir communication holes 14 are formed in two rows corresponding to the rows of the nozzle communication holes 13 and the reservoir communication holes 14.
[0028]
As shown in FIG. 4C, an elastic film 8 is formed on the upper surface of the pressure chamber forming substrate 7, and the upper surface openings of the plurality of pressure chambers 6 are sealed by the elastic film 8. On the upper surface of the elastic film 8, pedestal portions 24 for forming terminals are formed at opposite edges of the pressure chamber forming substrate 7 as shown in FIG.
[0029]
Further, as shown in FIG. 5A, a plurality of lower electrode films 9 and their connecting conductors 9a are provided on the upper surface of the elastic film 8 and the upper surface of the pedestal 24 so as to pass above the plurality of pressure chambers 6. And a printing process using a conductive material such as platinum. In FIG. 5A, reference numeral 25 denotes a pedestal that supports a part of the plurality of piezoelectric films 11.
[0030]
As shown in FIG. 5B, each piezoelectric film 11 is formed on the upper surface of each lower electrode film 9 by a printing process. A plurality of upper electrode films 12 are formed on the top surfaces of the plurality of piezoelectric films 11 as shown in FIG.
[0031]
As shown in FIG. 5D, each segment terminal 20 is formed on the pedestal portion 24 so as to be connected to each upper electrode film 12. A common terminal 21 connected to the lower electrode film 9 is also formed on the pedestal portion 24, and the common terminals 21 positioned at both ends of each row of the pressure chambers 6 are connected to each other by a terminal extension 26. ing. The terminal extension 26 is formed so as to overlap the connecting wire 9 a of the lower electrode film 9, whereby the common terminal 21 is electrically connected to the plurality of lower electrode films 9. The upper electrode film 12 at a position corresponding to the common terminal 21 is covered with the terminal extension 26, and the pressure chamber 6 at this position is not used.
[0032]
In the recording head according to the present embodiment, as shown in FIG. 2 , the interval d1 between the common terminal 21 and the segment terminal 20 adjacent thereto is set wider than the interval d2 between the adjacent segment terminals 20. ing. The distance d1 is desirably 0.1 mm or more.
[0033]
The widths of the segment terminals 20 and the common terminals 21 are all the same as measured along the longitudinal direction of the terminal row 22. The intervals between the segment terminals 20 are all equal.
[0034]
As described above, in the recording head according to the present embodiment, the interval d1 between the common terminal 21 and the segment terminal 20 adjacent to the common terminal 21 is set larger than the interval d2 between the segment terminals 20 and 0.1 mm or more. There is a low possibility that the common terminal 21 and the common terminal 21 are erroneously connected during the soldering operation in the mounting process of the recording head. As a result, the tolerance of alignment at the time of connecting the wiring to both terminals is increased, so that the manufacturing process can be easily managed. Further, even when the recording head is used, since the distance d1 between the segment terminal 20 and the common terminal 21 is sufficiently large, migration between both terminals hardly occurs, and a short circuit between both terminals can be prevented.
[0035]
In addition, since the widths of the segment terminals 20 and the common terminals 21 are all the same as measured along the longitudinal direction of the terminal row 22, the heat capacity of the solder at the time of soldering is the same in all the terminals 20 and 21. Become. Therefore, uniform soldering is possible when the plurality of terminals 20 and 21 are simultaneously soldered with an integrated heat tool. As a result, it is possible to shorten the time of the soldering work and improve the yield. .
[0036]
Next, an ink jet recording head according to a second embodiment of the present invention will be described with reference to FIG.
[0037]
FIG. 6 is a plan view of the actuator unit 35 of the recording head according to the present embodiment. The actuator unit 35 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.
[0038]
In the present embodiment, a pair of actuators 30 adjacent to each other is taken as one group, and each common terminal 21 is provided corresponding to each group. The lower electrode films of the pair of actuators 30 belonging to each group are connected by a common connection conducting wire 41. Each common connection conducting wire 41 has a thin wire portion 41 a extending between the actuators 30.
[0039]
As in the first embodiment, the interval d1 between the segment terminal 20 and the common terminal 21 adjacent to the segment terminal 20 is set wider than the interval d2 between the segment terminals 20 adjacent to each other.
[0040]
As described above, according to the ink jet recording head according to the present embodiment, the interval d1 between the common terminal 21 and the segment terminal 20 adjacent to the common terminal 21 is wider than the interval d2 between the segment terminals 20. The same effect as the form can be obtained.
[0041]
Further, since the plurality of actuators 30 are classified into several groups and each common terminal 21 is provided corresponding to each group, the overall length of the common connection conductor 41 is shortened, and a voltage drop is unlikely to occur. For this reason, sufficient conduction can be obtained without forming a film corresponding to the terminal extension 26 in the first embodiment, and the characteristics of the plurality of nozzle openings can be made uniform. The number of effective nozzle openings is not reduced because the actuators 30 at both ends are not disabled.
[0042]
FIG. 7 shows an actuator unit 45 according to a modification of the present embodiment. In this modification, the lower electrode films are connected to each other by the common connection conductor 42 at the end near the terminal row 22. Yes.
[0043]
According to this modification, the same effect as that of the above-described embodiment can be obtained, and it is not necessary to extend a thin conductive wire between the actuators 30. Therefore, there is a demand for printing accuracy when forming the common connection conductive wire 42. Alleviated.
[0044]
Next, an ink jet recording head according to a third embodiment of the invention will be described with reference to FIG.
[0045]
FIG. 8 is a plan view of the actuator unit 55 of the recording head according to the present embodiment. The actuator unit 55 includes one row of terminal rows 22 including a plurality of segment terminals 20 and a pair of common terminals 21 at one edge thereof.
[0046]
In the present embodiment, a plurality of actuators 30 are formed in two rows, and all rows of the actuators 30 are connected to a single terminal row 22. More specifically, the upper electrode film of the actuator 30 belonging to the row far from the terminal row 22 is used for the upper electrode extending between the actuators 30 belonging to the row closer to the terminal row 22. The connecting conductor 51 is connected to the segment terminal 20. Further, the lower electrode film of the actuator 30 belonging to the row closer to the terminal row 22 is connected to the lower electrode connecting conductor 52 extending between the actuators 30 belonging to the row farther from the terminal row 22. It is connected to the terminal extension 53. Both ends of the terminal extension 53 are connected to the pair of common terminals 21.
[0047]
Also in this embodiment, as in the above embodiments, the interval d1 between the segment terminal 20 and the common terminal 21 adjacent thereto is set wider than the interval d2 between the adjacent segment terminals 20. .
[0048]
As described above, according to the ink jet recording head according to the present embodiment, the interval d1 between the common terminal 21 and the segment terminal 20 adjacent to the common terminal 21 is made wider than the interval d2 between the segment terminals 20, so that each of the embodiments described above. The same effect can be obtained.
[0049]
Further, since all the rows of the plurality of actuators 30 are connected to the single terminal row 22, the soldering process to the terminal row 22 in the mounting process of the recording head is facilitated, and the recording head Miniaturization can be achieved.
[0050]
Next, an ink jet recording head according to a fourth embodiment of the invention will be described with reference to FIG.
[0051]
FIG. 9 is a plan view of the actuator unit 65 of the recording head according to the present embodiment. As shown in FIG. 9, this actuator unit 65 has a configuration in which the configuration of the actuator unit 55 of the third embodiment shown in FIG. 8 is integrally incorporated in one actuator unit 65. .
[0052]
Also in the ink jet recording head according to the present embodiment, the distance d1 between the common terminal 21 and the segment terminal 20 adjacent to the common terminal 21 is made wider than the distance d2 between the segment terminals 20, so the same effects as in the above embodiments. Is obtained.
[0053]
Further, since a plurality of rows (two rows) of actuators 30 are connected to each of the pair of terminal rows 22, the soldering process to the terminal rows 22 during the mounting process of the recording head is facilitated, and the recording is performed. The size of the head can be reduced.
[0054]
Next, an ink jet recording head according to a fifth embodiment of the invention will be described with reference to FIG.
[0055]
FIG. 10 is a plan view of the actuator unit 75 of the recording head according to the present embodiment. The actuator unit 75 includes a pair of terminal rows 22 formed at a pair of opposite edge portions and a central terminal row 22 disposed between the pair of terminal rows 22. Both rows of the pair of actuators 30 located on both sides of the actuator are connected to the central terminal row 22.
[0056]
Also in the ink jet recording head according to the present embodiment, the distance d1 between the common terminal 21 and the segment terminal 20 adjacent thereto is set in each of the terminal row 22 and the central terminal row 22 at both edges of the actuator unit 75. Since the distance d2 is larger than the interval d2 between the segment terminals 20, the same effect as the above embodiments can be obtained.
[0057]
Further, according to the present embodiment, since two actuators 30 are connected to the central one terminal row 22, a total of three terminal rows 22 are provided for a total of four actuators 30. Therefore, the soldering process to the terminal row 22 during the mounting process of the recording head is facilitated, and the recording head can be reduced in size.
[0058]
【The invention's effect】
As described above, according to the present invention, since the interval between the common terminal and the segment terminal adjacent to the common terminal is made wider than the interval between the segment terminals, wiring can be easily and accurately connected to each terminal. In addition, even when the recording head is used, since the interval between the segment terminal and the common terminal is sufficiently large, migration between both terminals hardly occurs, and a short circuit between both terminals can be prevented.
[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 ink jet recording head according to the first embodiment of the invention.
FIG. 3 is a perspective view of the actuator unit of the ink jet recording head according to the first embodiment of the 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 invention.
FIG. 5 is a plan view showing each layer of the actuator unit of the ink jet recording head according to the first embodiment of the invention.
FIG. 6 is a plan view of an actuator unit of an ink jet recording head according to a second embodiment of the invention.
FIG. 7 is a plan view of an actuator unit of an ink jet recording head according to a modification of the second embodiment of the present invention.
FIG. 8 is a plan view of an actuator unit of an ink jet recording head according to a third embodiment of the invention.
FIG. 9 is a plan view of an actuator unit of an ink jet recording head according to a fourth embodiment of the invention.
FIG. 10 is a plan view of an actuator unit of an ink jet recording head according to a fifth embodiment of the invention.
FIG. 11 is a plan view of an actuator unit of a conventional ink jet recording head.
FIG. 12 is a perspective view 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 formation board | substrate 4 Communication hole formation board | substrate 5, 35, 45, 55, 65, 75 Actuator unit 6 Pressure chamber 7 Pressure chamber formation board 8 Elastic film 9 Lower electrode film 11 Piezoelectric film 12 Upper part 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 30 Actuator 41, 42 Common connection lead d1 Common The distance between the terminal and the segment terminal adjacent to the terminal d2 The distance between the segment terminals adjacent to each other

Claims (11)

A plurality of pressure chambers respectively communicating with the plurality of nozzle openings;
An elastic membrane constituting one wall surface of the pressure chamber;
A plurality of actuators formed on the elastic membrane corresponding to the plurality of pressure chambers;
A terminal row composed of a plurality of terminals connected to the plurality of actuators,
The plurality of actuators include 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 the plurality of actuators. A plurality of upper electrode films formed on the piezoelectric film,
The plurality of terminals include a plurality of segment terminals provided corresponding to each of the plurality of upper electrode films, and at least one common terminal shared in all or part of the plurality of lower electrode films. Have
An interval between the common terminal and the segment terminal adjacent to the common terminal is wider than an interval between the segment terminals adjacent to each other.
The segment terminals and the common terminals are aligned in width measured along the longitudinal direction of the terminal row,
The actuator unit characterized in that intervals between the segment terminals are equal. The plurality of lower electrode films are classified into several groups, and each common terminal is provided corresponding to each group,
2. The actuator unit according to claim 1, further comprising each common connection conductor that connects the lower electrode films belonging to each group and connects the lower electrode film to the corresponding common terminal.   3. The actuator unit according to claim 2, wherein a pair of the lower electrode films belong to each group.   4. The actuator according to claim 2, wherein the common connecting conductor is formed on the same plane as the lower electrode film, and has a portion extending between the adjacent actuators. 5. unit.   4. The actuator unit according to claim 2, wherein the common connecting wire connects ends of the lower electrode films adjacent to each other on a side close to the terminal row. 5. The plurality of actuators are formed in a plurality of rows, and a row of terminals composed of the plurality of terminals is formed,
The actuator unit according to claim 1, wherein a plurality of rows of the actuators are connected to the single terminal row.   The actuator unit according to claim 6, wherein the single terminal row is formed at one edge of the actuator unit. The plurality of actuators are formed in a plurality of rows, and a plurality of terminal rows made of the plurality of terminals are formed,
2. The actuator unit according to claim 1, wherein at least two of the plurality of actuators are connected to at least one of the plurality of terminal rows. 3.   The actuator unit according to claim 8, wherein the plurality of terminal rows are formed on a pair of opposite edges of the actuator unit.   At least one of the plurality of terminal rows is arranged between the rows of the actuators and is connected to both of the pair of the actuator rows located on both sides thereof. Item 9. The actuator unit according to Item 8. The actuator unit according to any one of claims 1 to 10,
An ink jet recording head, comprising: a nozzle plate having a plurality of nozzle openings.

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