JP2022095995A - Actuator device and liquid ejection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a short circuit between adjacent through-hole electrodes even in a case where piezoelectric elements are arrayed at narrow intervals.

SOLUTION: An actuator device comprises: a piezoelectric actuator having a plurality of piezoelectric elements 41 arrayed in forward and backward directions, and a plurality of drive contacts 57 respectively drawn out from the plurality of piezoelectric elements 41; a protective member joined to an arrangement area of the drive contacts 57 of the piezoelectric actuator; a plurality of individual terminals arranged on a face, opposite the piezoelectric actuator, of a top wall part of the protective member; and a plurality of first through-hole electrodes 71, formed on a partition wall part of the protective member, respectively conducting with the drive contacts 57 and the individual terminals. An interval P2 between two first through-hole electrodes 71 corresponding to two piezoelectric elements 41 adjacent to each other in forward and backward directions is wider than an interval P1 between the two piezoelectric elements 41 adjacent to each other in the forward and backward directions.

SELECTED DRAWING: Figure 7

COPYRIGHT: (C)2022,JPO&INPIT

Description

The present invention relates to an actuator device and a liquid discharge device.

Patent Document 1 discloses a liquid discharge device that discharges a liquid from a nozzle. This liquid discharge device includes a flow path member (flow path forming substrate) in which a plurality of pressure chambers communicating with each other are formed, a piezoelectric actuator having a plurality of piezoelectric elements corresponding to a plurality of pressure chambers, and a plurality of piezoelectric elements. It includes a protective member (protective substrate) arranged on the piezoelectric actuator so as to cover the element, and a drive circuit arranged on the protective member.

In this liquid discharge device, the contacts drawn from each piezoelectric element of the piezoelectric actuator are electrically connected to a drive circuit arranged on the upper surface of the protective member via a through electrode penetrating the protective member.

Specifically, first, the contact drawn from the piezoelectric element is arranged in the joint region of the piezoelectric actuator with the protective member. On the other hand, a through hole is formed in the wall portion of the protective member that covers the piezoelectric element, and a through electrode is formed by filling the through hole with a conductive material. Through the through electrodes, the contacts on the piezoelectric actuator side and the contacts formed on the upper surface of the protective member are electrically connected. Further, the contacts on the upper surface of the protective member are connected to the drive circuit by wiring arranged on the upper surface.

Japanese Unexamined Patent Publication No. 2006-192685

By the way, in recent years, from the viewpoint of miniaturization of the liquid discharge device, a configuration in which nozzles and pressure chambers are arranged at high density is desired. Here, as the arrangement spacing of the pressure chambers becomes smaller, the arrangement spacing of the piezoelectric elements becomes smaller accordingly, so that the spacing of the through electrodes formed on the protective member corresponding to the piezoelectric elements also becomes smaller.

Furthermore, if the through electrodes are to be arranged at narrow intervals, the size of each through electrode needs to be reduced. That is, if only the spacing is reduced while the size of the through electrodes is large, the separation distance between the adjacent through electrodes is shortened by that amount, and the probability of short circuit increases. However, in reality, there is a limit to reducing the diameter of the through hole formed in the protective member, and it is difficult to reduce the size of the through electrode to a certain level or less.

An object of the present invention is to prevent the occurrence of a short circuit between adjacent through electrodes even when the piezoelectric elements are arranged at small intervals.

The actuator device of the present invention has an actuator having a plurality of piezoelectric elements arranged in a first direction and a plurality of first contacts drawn from the plurality of piezoelectric elements and arranged along the first direction. The second wall portion of the actuator has a first wall portion facing the piezoelectric element and a second wall portion connected to the first wall portion, and the second wall portion covers the piezoelectric element. A protective member joined to the arrangement region of one contact, a plurality of first connection terminals arranged on the surface of the first wall portion of the protective member opposite to the actuator, and the second of the protective member. Each of the plurality of first through holes formed in the wall portion is provided with a plurality of first through electrodes each conducting the first contact and the first connection terminal.
The distance between the two first through electrodes corresponding to the two adjacent piezoelectric elements in the first direction is larger than the distance between the two adjacent piezoelectric elements in the first direction. It is a thing.

It is a schematic plan view of the printer 1 which concerns on this embodiment. It is a top view of the head unit 16. It is a top view of the head unit 16 (simplification of driver IC 37 and FPC 27). It is a top view of the head unit 16 (the protective member is not shown). FIG. 4 is a sectional view taken along line VV of FIG. It is sectional drawing of the partition wall part 55 of protection member 26, (a) is the sectional view at the part where the 1st through electrode 71 was formed, (b) is the sectional view at the part where the 2nd through electrode 72 was formed. Is. It is a figure which shows the arrangement relation of a piezoelectric element 41, a drive contact 57, and a 1st through electrode 71. It is a figure which shows the arrangement relation of the piezoelectric element 41, the drive contact 57, and the 1st through electrode 71 in the comparative form. It is a figure which shows the manufacturing process of a protective member 26. It is a figure which shows the process from the joining of a protective member 26 to the joining of a driver IC 37 and FPC 27. It is sectional drawing of the part where the 1st through silicon via 71A of the protection member 26A was formed of the modified form. It is sectional drawing of the part where the 1st through silicon via 71B of the protective member 26B was formed, which is another modified form. It is a top view of the head unit 16C of another modified form. It is a top view of the head unit 16D of another modified form. It is sectional drawing of the head unit 16D of FIG. It is sectional drawing of the head unit 16E of another modified form. It is sectional drawing of the head unit 16F of another modified form. It is a figure which shows the arrangement relation of the piezoelectric element 41, the drive contact 57, and the 1st through electrode 71 in the head unit of FIG. It is a figure which shows the arrangement relation of the piezoelectric element 41, the drive contact 57G, and the 1st through electrode 71 in another modified form. It is a top view of the head unit 16H of another modified form.

Next, an embodiment of the present invention will be described. First, a schematic configuration of the inkjet printer 1 will be described with reference to FIG. In FIG. 1, the direction in which the recording paper 100 is conveyed is defined as the front-back direction of the printer 1. Further, the width direction of the recording paper 100 is defined as the left-right direction of the printer 1. Further, the vertical direction on the paper surface of FIG. 1, which is orthogonal to the front-back direction and the left-right direction, is defined as the vertical direction of the printer 1.

(Approximate configuration of printer)
As shown in FIG. 1, the inkjet printer 1 includes a platen 2, a carriage 3, an inkjet head 4, a transport mechanism 5, a control device 6, and the like.

The carriage 3 is attached to two guide rails 10 and 11 extending in the left-right direction (hereinafter, also referred to as a scanning direction). Further, the carriage 3 is connected to the carriage drive motor 15 via an endless belt 14. The carriage 3 is driven by a motor 15 and reciprocates on the recording paper 100 of the platen 2 in the scanning direction.

The inkjet head 4 is attached to the carriage 3 and moves in the scanning direction together with the carriage 3. The inkjet head 4 includes four head units 16 arranged in the scanning direction. The four head units 16 are connected to the ink cartridges 17 of the four colors (black, yellow, cyan, magenta) of the holder 7, respectively.

Each head unit 16 has a plurality of nozzles 36 (see FIGS. 4 and 5) formed on the lower surface thereof (the surface on the other side of the paper surface in FIG. 1). The nozzle 36 of each head unit 16 ejects the ink supplied from the ink cartridge 17 toward the recording paper 100 mounted on the platen 2. The details of the head unit 16 will be described later.

The transport mechanism 5 transports the recording paper 100 on the platen 2 forward (hereinafter, also referred to as a transport direction) by the two transport rollers 18 and 19. The control device 6 controls the inkjet head 4, the carriage drive motor 15, and the like based on a print command input from an external device such as a PC, and causes the recording paper 100 to print an image or the like.

<Details of head unit>
Next, the configuration of the head unit 16 of the inkjet head 4 will be described in detail. Since each of the four head units 16 has the same configuration, one of the four head units 16 will be described below.

As shown in FIGS. 2 to 5, the head unit 16 includes an actuator device 25 including a first flow path member 21, a second flow path member 22, a nozzle plate 23, and a piezoelectric actuator 24. The actuator device 25 of the present embodiment does not refer only to the piezoelectric actuator 24, but includes a protective member 26 arranged on the piezoelectric actuator 24, a driver IC 37 joined to the protective member 26, and a wiring member. It is a concept including a certain FPC (Flexible Printed Circuit) 27.

(1st flow path member, 2nd flow path member, nozzle plate)
First, the first flow path member 21, the second flow path member 22, and the nozzle plate 23 will be described. Each of the above three members is made of a silicon single crystal substrate, and is laminated vertically in the order of the first flow path member 21, the second flow path member 22, and the nozzle plate 23 from the top.

The first flow path member 21 is formed with a plurality of pressure chambers 28 arranged in a plane along the horizontal plane. Each pressure chamber 28 has a rectangular planar shape that is long in the scanning direction. The plurality of pressure chambers 28 are arranged in the transport direction to form two pressure chamber rows arranged in the scanning direction. Further, the positions of the pressure chambers 28 in the transport direction are different from each other between the two pressure chamber rows. More specifically, when the arrangement interval of the pressure chambers 28 in each pressure chamber row is P0, the position of the pressure chamber 28 in the transport direction is shifted by P0 / 2 between the two pressure chamber rows on the left and right. There is.

As shown in FIG. 5, a vibrating film 40 of a piezoelectric actuator 24 described later is formed on the upper surface of the first flow path member 21, and a plurality of pressure chambers 28 are covered by the vibrating film 40. The vibrating film 40 is, for example, a film formed by oxidizing or nitriding the surface of a silicon substrate.

As shown in FIGS. 2 to 4, the second flow path member 22 has a planar shape slightly larger than that of the first flow path member 21, and projects outward from the first flow path member 21 over the entire circumference. There is. As shown in FIGS. 4 and 5, two manifolds 30 corresponding to the two pressure chamber rows are formed at the left and right two ends of the second flow path member 22 protruding from the first flow path member 21, respectively. ing. Ink from one ink cartridge 17 (see FIG. 1) is supplied to the two manifolds 30. That is, ink of the same color is supplied to the two manifolds 30. Each manifold 30 communicates with a plurality of pressure chambers 28 that make up the corresponding pressure chamber row.

A plurality of nozzles 36 corresponding to the plurality of pressure chambers 28 are formed on the nozzle plate 23. Each nozzle 36 communicates with the pressure chamber 28 of the first flow path member 21. The plurality of nozzles 36 correspond to the arrangement of the pressure chambers 28 and are arranged in two rows. The position of the nozzle 36 in the transport direction is shifted by P0 / 2 between the two nozzle rows.

(Piezoelectric actuator device)
An actuator device 25 is arranged on the upper surface of the first flow path member 21. As mentioned earlier, the actuator device 25 includes a piezoelectric actuator 24 including a plurality of piezoelectric elements 41, a protective member 26, a driver IC 37, and an FPC 27.

<Piezoelectric actuator>
The piezoelectric actuator 24 is arranged on the entire upper surface of the first flow path member 21. As shown in FIGS. 4 and 5, the piezoelectric actuator 24 has a vibrating membrane 40 and a plurality of piezoelectric elements 41 arranged on the vibrating membrane 40.

As described above, the vibrating film 40 is formed on the upper surface of the first flow path member 21 and covers the plurality of pressure chambers 28. The thickness of the vibrating membrane 40 is, for example, 1.0 to 1.5 μm. A plurality of piezoelectric elements 41 are arranged at positions on the upper surface of the vibrating membrane 40 so as to overlap with the plurality of pressure chambers 28. The plurality of piezoelectric elements 41 form two piezoelectric element rows 47 arranged in the scanning direction according to the arrangement of the pressure chambers 28. The position of the piezoelectric element 41 in the front-rear direction is displaced by P0 / 2 between the two piezoelectric element rows 47.

The configuration of each piezoelectric element 41 will be described. Each piezoelectric element 41 has a lower electrode 42 arranged on the vibrating film 40, a piezoelectric film 43 arranged on the lower electrode 42, and an upper electrode 44 arranged on the piezoelectric film 43.

The lower electrode 42 is arranged on the upper surface of the vibrating membrane 40 so as to overlap the pressure chamber 28. The lower electrode 42 is a so-called individual electrode separated from each other among the plurality of piezoelectric elements 41. A drive signal is individually supplied from the driver IC 37 to the lower electrode 42 of each piezoelectric element 41. As shown in FIGS. 4 and 7, one end of the lower electrode 42 extends inward in the scanning direction and is exposed from the piezoelectric body 46. The lower electrode 42 is made of, for example, platinum (Pt). The thickness thereof is, for example, 0.1 μm.

The piezoelectric film 43 is formed of a piezoelectric material such as lead zirconate titanate (PZT). The thickness of the piezoelectric film 43 is, for example, 1.0 to 2.0 μm. As shown in FIGS. 3 to 5, in the present embodiment, the piezoelectric film 43 is connected between the piezoelectric elements 41 of the piezoelectric element row 47 on the left side, and the piezoelectric film 43 is also connected between the piezoelectric elements 41 of the piezoelectric element row 47 on the right side. ing. That is, on the vibrating membrane 40, two piezoelectric bodies 46, a piezoelectric body 46 that covers the pressure chamber row on the left side and a piezoelectric body 46 that covers the pressure chamber row on the right side, are arranged.

The upper electrode 44 is arranged on the upper surface of the piezoelectric film 43. The upper electrode 44 is made of, for example, iridium. The thickness of the upper electrode 44 is, for example, 0.1 μm. On the upper surface of the piezoelectric body 46, the upper electrodes 44 corresponding to the plurality of pressure chambers 28 are connected to each other to form a common electrode 49 that covers almost the entire upper surface of the piezoelectric body 46. A ground potential is applied to the upper electrode 44 (common electrode 49) from the FPC 27 described later. An auxiliary conductor 50 having a thickness larger than that of the common electrode 49 is provided on the common electrode 49. The auxiliary conductor 50 is made of, for example, gold (Au).

A drive wiring 52 is connected to an end of the lower electrode 42 exposed from the piezoelectric body 46. Each drive wiring 52 extends further inward in the scanning direction from the end of the corresponding lower electrode 42. The drive wiring 52 is made of, for example, gold (Au).

The drive wiring 52 extends to the region between the two piezoelectric element rows 47. A drive contact 57 is provided at the end of the drive wiring 52. The drive contacts 57 of the plurality of drive wirings 52 are arranged in the transport direction in the region between the two piezoelectric element rows 47. More specifically, as shown in FIGS. 4 and 7, between the two piezoelectric element rows 47, a contact row 56 composed of a plurality of drive contacts 57 drawn from the left piezoelectric element row 47 and a piezoelectric row 56 on the right side. Two contact rows 56 of a contact row 56 composed of a plurality of drive contacts 57 drawn from the element row 47 are arranged side by side in the left-right direction. Further, as in the case of the two piezoelectric element rows 47, the position of the drive contact 57 in the front-rear direction is shifted by P0 / 2 between the two contact rows 56.

As shown in FIG. 4, the two common electrodes 49 arranged on the upper surfaces of the two piezoelectric bodies 46 are connected by the conductive portion 50a of the auxiliary conductor 50 extending across the two piezoelectric bodies 46. A ground contact 58 is provided at a portion of the conductive portion 50a that is aligned with the plurality of drive contacts 57 in the front-rear direction. That is, a plurality of drive contacts 57 and two ground contacts 58 located outside in the front-rear direction of the plurality of drive contacts 57 are arranged between the two piezoelectric element rows 47.

<Protective member, driver IC, FPC>
As shown in FIGS. 2 to 5, the protective member 26 is bonded to the upper surface of the piezoelectric actuator 24 with an adhesive so as to cover the plurality of piezoelectric elements 41. As the adhesive, a conductive adhesive 60 containing conductive particles is used. The material of the protective member 26 is not particularly limited, but a silicon substrate can be preferably used.

As shown in FIG. 5, the protective member 26 has a top wall portion 53, two side wall portions 54, and a partition wall portion 55. The top wall portion 53 is arranged so as to face the plurality of piezoelectric elements 41. The two side wall portions 54 are connected to both ends in the left-right direction of the top wall portion 53, and extend in the front-rear direction (vertical direction on the paper surface in FIG. 5). The partition wall portion 55 is connected to the central portion in the left-right direction of the top wall portion 53, and extends in the front-rear direction at a position between the two side wall portions 54.

The two side wall portions 54 of the protective member 26 are joined to regions on the upper surface of the piezoelectric actuator 24 on the outer side in the left-right direction of the two piezoelectric element rows 47, respectively. On the other hand, the partition wall portion 55 is joined to the region between the two piezoelectric element rows 47 on the upper surface of the piezoelectric actuator 24, that is, the region where the contacts 57 and 58 are arranged. The partition wall portion 55 divides the inner space of the protective member 26 into two spaces each accommodating two left and right piezoelectric element rows 47. In the present embodiment, the width of the partition wall portion 55 in the left-right direction is larger than the width of one side wall portion 54.

The driver IC 37 is arranged on the upper surface of the central portion in the left-right direction connected to the partition wall portion 55 of the top wall portion 53. FPC27 is joined to the upper surface of the right end portion of the top wall portion 53 connected to the right side wall portion 54.

The protective member 26 not only has a role of protecting a plurality of piezoelectric elements 41, but also has a role of forming wiring for connecting the contacts 57 and 58 of the piezoelectric actuator 24 to the driver IC 37 and the FPC 27. .. Hereinafter, the wiring structure for connecting the piezoelectric actuator 24 of the protective member 26 to the driver IC 37 and the FPC 27 will be described.

As shown in FIGS. 2 and 3, a plurality of input terminals 61 arranged in the front-rear direction are arranged on the upper surface of the right end portion of the top wall portion 53 connected to the right side wall portion 54. The plurality of input terminals 61 include a signal input terminal 62 and a ground input terminal 63. An FPC 27 is joined to the right end of the top wall portion 53 by a conductive adhesive 64, and a plurality of input terminals 61 and the FPC 27 are electrically connected. The end of the FPC 27 on the opposite side of the protective member 26 is connected to the control device 6 (see FIG. 1) of the printer 1.

On the upper surface of the top wall portion 53 of the protective member 26, which is connected to the partition wall portion 55 in the left-right direction, a plurality of individual terminals 65 arranged in the front-rear direction, two first ground terminals 67, and a plurality of signal terminals. 66 and two second ground terminals 70 are formed.

The plurality of individual terminals 65 are arranged corresponding to the plurality of drive contacts 57 of the piezoelectric actuator 24, and are arranged in two rows in a staggered manner. The two first ground terminals 67 correspond to the two ground contacts 58 of the piezoelectric actuator 24, and are arranged on both sides of the plurality of individual terminals 65 in the front-rear direction. The plurality of signal terminals 66 are arranged in the front-rear direction on the right side of the plurality of individual terminals 65. The two second ground terminals 70 are arranged on both sides of the plurality of individual terminals 65 in the front-rear direction.

A driver IC 37 is joined to the upper surface of the central portion in the left-right direction of the top wall portion 53 by a conductive adhesive 64, and a plurality of individual terminals 65, a plurality of signal terminals 66, and two ground terminals 70 are electrically connected to the driver IC 37. Is connected.

The signal input terminal 62 connected to the FPC 27 and the signal terminal 66 connected to the driver IC 37 are connected by a signal wiring 68 extending in the left-right direction on the upper surface of the top wall portion 53. The ground input terminal 63 is connected to the first ground terminal 67 and the second ground terminal 70 by a ground wiring 69 (wiring portions 69a, 69b) formed on the upper surface of the top wall portion 53. Specifically, the ground input terminal 63 is connected to the first ground terminal 67 by a wiring portion 69a extending in the left-right direction and the front-back direction. Further, the ground input terminal 63 is connected to the second ground terminal 67 by a wiring portion 69b that branches from the middle of the wiring portion 69a and extends to the left and right. The wiring and terminals on the top wall portion 53 such as the signal wiring 68, the ground wiring 69, the individual terminal 65, the signal terminal 66, the ground terminal 67, 70, and the input terminal 61 are formed of, for example, gold (Au). To.

On the other hand, the partition wall portion 55 is formed with a plurality of vertically extending first through electrodes 71 and two second through electrodes 72 arranged on both front and rear sides of the plurality of first through electrodes 71. The first through electrode 71 is conductive with the drive contact 57 of the lower piezoelectric actuator 24 and the individual terminal 65 of the upper top wall portion 53. The second through electrode 72 is conductive with the ground contact 58 of the lower piezoelectric actuator 24 and the first ground terminal 67 of the upper top wall portion 53.

A control signal is input from the control device 6 to the driver IC 37 via the FPC 27, the signal input terminal 62 of the protective member 26, the signal wiring 68, and the signal terminal 66. Based on this control signal, the driver IC 37 outputs a drive signal to each of the plurality of piezoelectric elements 41. The drive signal is applied to the lower electrode 42 of each piezoelectric element 41 via the individual terminal 65, the first through electrode 71, and the drive contact 57 of the piezoelectric actuator 24.

On the other hand, although not shown, a ground line is formed on the FPC 27. This ground wire is connected to the common electrode 49 (upper electrode 44) of the piezoelectric actuator 24 via the ground input terminal 63, the wiring portion 69a, the first ground terminal 67, the second through electrode 72, and the ground contact 58. To. As a result, the potential of the upper electrode 44 is maintained at the ground potential. The ground wire of the FPC 27 is also connected to the driver IC 37 via the ground input terminal 63, the wiring portion 69b, and the second ground terminal 70.

As shown in FIGS. 2 and 3, the plurality of individual terminals 65 of the top wall portion 53 correspond to the plurality of piezoelectric elements 41, and are provided in the same number as the drive contacts 57. On the other hand, the plurality of input terminals 61 (62, 63) connected to the FPC 27 are mainly terminals to which signals for controlling the driver IC 37 are input, and the number is smaller than that of the individual terminals 65. .. Therefore, the arrangement length of the plurality of input terminals 61 in the front-rear direction is shorter than the arrangement length of the plurality of individual terminals 65. Moreover, in the present embodiment, the width of the FPC 27 in the front-rear direction is smaller than that of the driver IC 37. This makes it possible to reduce the size and cost of the FPC 27. Further, as the width of the FPC 27 becomes smaller, the handling of the FPC 27 becomes easier.

<Details of through electrodes>
Next, the details of the through electrodes 71 and 72 formed on the partition wall portion 55 of the protective member 26 will be described. As shown in FIGS. 5 and 6A, a plurality of first through holes 73 that vertically penetrate the partition wall portion 55 are provided at positions overlapping with the plurality of drive contacts 57 in the central portion in the left-right direction of the partition wall portion 55. It is formed. The plurality of first through holes 73 are filled with a conductive material (for example, copper (Cu)) to form a plurality of vertically extending first through electrodes 71.

As shown in FIGS. 5 and 6 (b), two second through holes 74 are formed at positions overlapping with the two front and rear ground contacts 58 in the central portion in the left-right direction of the partition wall portion 55. The two second through holes 74 are also filled with the same conductive material as the first through holes 73, and two vertically extending second through electrodes 72 are formed. In this embodiment, the hole diameter of the second through hole 74 is the same as the hole diameter of the first through hole 73. That is, the diameter of the second through electrode 72 is the same as that of the first through electrode 71.

Since the plurality of drive contacts 57 drawn from these two piezoelectric element rows 47 are densely arranged between the two piezoelectric element rows 47, the area of each drive contact 57 is small. .. On the other hand, as will be described later, it is difficult to make the hole diameter of the first through hole 73 as small as that of the drive contact 57 by etching, and the hole has a certain size or more. As a result, as shown in FIGS. 6 and 7, the area of the lower end surface of the first through electrode 71 is larger than the area of the drive contact 57 provided at the tip of the drive wiring 52. More specifically, the diameter of the lower end surface of the first through electrode 71 is larger than the width of the drive contact 57 in the front-rear direction. Further, for the same reason, as shown in FIGS. 3 and 5, the individual terminals 65 on the upper end surface of the top wall portion 53 are also formed smaller than the first through electrode 71. That is, the area of the upper end surface of the first through electrode 71 is larger than the area of the individual terminals 65 on the upper surface of the top wall portion 53.

On the other hand, when many piezoelectric elements 41 are driven at the same time, a large current flows through the common electrode 49. Therefore, in order to keep the voltage drop small, it is desired to keep the resistance of the path connected to the common electrode 49 small. From this point of view, as shown in FIGS. 2, 3, and 6 (b), the area of the ground contact 58 and the first ground terminal 67 is larger than the area of the end face of the second through electrode 72. ..

On top of that, insulating films 75 and 76 are formed on the lower surface joined to the piezoelectric actuator 24 of the protective member 26 and on the upper surface on the opposite side, respectively. In the region overlapping the first through hole 73 of the lower insulating film 75, a hole 75a having a smaller area than the lower end surface of the first through electrode 71 is formed. That is, the exposed area (joint area with the drive contact 57) of the lower end surface of the first through electrode 71 is limited by the hole 75a. Further, in the region overlapping the first through hole 73 of the upper insulating film 76, a hole 76a having a smaller area than the upper end surface of the first through electrode 71 is formed. As a result, the exposed area (joint area with the individual terminal 65) of the upper end surface of the first through electrode 71 is also limited to be small by the hole 76a. The holes 75b and 76b are also formed in the regions overlapping the second through holes 74 of the insulating films 75 and 76, respectively, but these holes 75b and 76b have substantially the same area as the end face of the second through electrode 72. It is a hole.

The protective member 26 is joined to the upper surface of the piezoelectric actuator 24 by a conductive adhesive 60. The conductive adhesive 60 (ACF or ACP) is an adhesive in which conductive particles are mixed with a thermosetting resin such as an epoxy resin. The contacts 57, 58 of the piezoelectric actuator 24 and the through electrodes 71, 72 of the protective member 26 are electrically conductive by the conductive particles contained in the conductive adhesive 60.

With the conductive adhesive 60 interposed between the contacts 57 and 58 on the piezoelectric actuator 24 side and the through electrodes 71 and 72 on the protective member 26 side, both are pressed while being heated. At this time, the adhesive 60 is compressed between the contacts 57, 58 and the through electrodes 71, 72, and the contacts 57, 58 and the through electrodes 71, 72 are electrically charged by the conductive particles contained in the adhesive 60. Be connected. At the same time, the thermosetting resin, which is the main component of the adhesive 60, flows out from between the contacts 57 and 58 and the through electrodes 71 and 72 to the surroundings and is heat-cured. As a result, the piezoelectric actuator 24 and the protective member 26 are mechanically joined. In addition, in FIGS. 5 and 6, among the joint regions formed by the conductive adhesive 60, the portions where the conduction due to the conductive particles is generated are distinguished from the surrounding mechanical joint portions by thickening the hatching.

By the way, particularly with respect to the first through hole 73, it is preferable that the hole diameter of the first through hole 73 is small from the viewpoint of densely arranging many first through electrodes 71. However, in reality, there is a limit to reducing the hole diameter.

This will be described by taking as an example the case where a through hole is formed by etching. Assuming that the thickness of the member forming the hole is t, the minimum value of the hole diameter when formed by etching is about t / 10. That is, the thicker the member, the larger the hole diameter of the through hole tends to be. Here, the protective member 26 is originally a member for protecting the piezoelectric element 41, and needs to have a certain thickness or more in order to realize its function. Further, if the thickness of the protective member 26 is thin, handling when joining to the piezoelectric actuator 24 becomes difficult. Therefore, from this viewpoint as well, the protective member 26 is required to have a certain thickness. From the above, when the first through hole 73 is formed by etching, the hole diameter of the first through hole 73 has to be increased to some extent.

As the hole diameter of the first through hole 73 becomes larger, the separation distance between the two adjacent first through electrodes 71 becomes smaller, and the probability that a short circuit occurs between the two first through electrodes 71 increases. .. In particular, in the present embodiment, the protective member 26 is bonded to the piezoelectric actuator 24 with the conductive adhesive 60, but the conductive particles contained in the conductive adhesive 60 flow out around the contacts together with the thermosetting resin. Occasionally, the smaller the separation distance between the first through electrodes 71, the more likely it is that short circuits will occur due to conductive particles.

Therefore, in the present embodiment, the following configuration is adopted in order to reduce the separation distance of the first through silicon vias 71 adjacent to each other in the front-rear direction. First, as described above, the plurality of drive contacts 57 of the piezoelectric actuator 24 are arranged in a staggered pattern to form two contact rows 56. As shown in FIGS. 3 and 7, a plurality of first through electrodes 71 are also arranged in a staggered pattern corresponding to the arrangement of the drive contacts 57, and two of them extend in the front-rear direction and are arranged in the left-right direction. It constitutes the electrode row 77. Similar to the two contact rows 56, the position of the first through silicon via 71 in the front-rear direction is shifted between the two electrode rows 77 by P1 = (P0 / 2).

Then, as shown in FIG. 7, in the present embodiment, the distance P2 between the two first through electrodes 71 corresponding to the two piezoelectric elements 41 adjacent in the front-rear direction is between the two piezoelectric elements 41. It is larger than the interval P1. More specifically, the distance between the plurality of first through electrodes 71 is the smallest between the first through electrode 71 belonging to the left electrode row 77 and the first through electrode 71 belonging to the right electrode row 77. Is the direction along the straight line L connecting the centers of both. Then, in the present embodiment, the distance P2 between the two first through electrodes 71 along the straight line L corresponds to the distance P1 in the front-rear direction of the two piezoelectric elements 41 corresponding to the two first through electrodes 71, respectively. = It is larger than P0 / 2).

A comparative form with respect to FIG. 7 is shown in FIG. In FIG. 8, a plurality of drive contacts 57 drawn out from the two piezoelectric element rows 47 are arranged in a row at an interval P1 in the front-rear direction. In this case, the two closest first through electrodes 71 The interval between them is also P1. On the other hand, in FIG. 7 of the present embodiment, the distance between the two closest through silicon vias 71 is larger than that in FIG. In other words, in the present embodiment, the plurality of drive contacts 57 of the piezoelectric actuator 24 are divided into two left and right contact rows 56, and the plurality of first through electrodes 71 of the protective member 26 are also divided into two left and right electrode rows 77. Therefore, the shortest distance between the adjacent first through electrodes 71 is increased.

For example, as described above, when the thickness t of the protective member 26 is 400 μm, the hole diameter d of the first through hole 73 is at least 40 μm (= t / 10). On the other hand, when the arrangement spacing P0 of the nozzles 36 in one nozzle row is 300 dpi (= 84 μm), the spacing P1 = P0 / 2 = 42 μm between the two piezoelectric elements 41 adjacent in the front-rear direction. In this case, as shown in FIG. 8, when a plurality of first through electrodes 71 are arranged in a row at intervals of P1 in the front-rear direction, there is almost no gap between the two first through electrodes 71 adjacent to each other in the front-rear direction. Will end up. On the other hand, when the plurality of first through electrodes 71 are divided into two left and right electrode rows 77 as shown in FIG. 7, the distance P2 between the adjacent first through electrodes 71 can be widened to about 60 μm. can.

As described above, the distance P2 between the two first through electrodes 71 corresponding to the two piezoelectric elements 41 adjacent in the front-rear direction is larger than the distance P1 in the front-rear direction of the two piezoelectric elements 41. As a result, even when the arrangement interval P0 of one nozzle row is considerably small (for example, 300 dpi), it is possible to prevent a short circuit between two adjacent first through electrodes 71.

As shown in FIG. 6A, the lower end surface of the first through electrode 71 is covered with the insulating film 75 in which the small holes 75a are formed, and the area of the lower end surface of the first through electrode 71 is substantially small. It has become. In this configuration, at the lower end joined to the drive contact 57, the gap between the adjacent first through electrodes 71 becomes large, and a short circuit can be prevented more reliably. Further, the above configuration is particularly effective when the area of the lower end surface of the first through electrode 71 is larger than the area of the drive contact 57.

Further, the upper end surface of the first through electrode 71 is also covered with the insulating film 76 in which the small holes 76a are formed, and the area of the upper end surface of the first through electrode 71 is also substantially reduced. As a result, even at the upper end of the joint with the driver IC 37, the gap between the adjacent first through silicon vias 71 becomes large, and a short circuit can be prevented more reliably.

As shown in FIG. 3, it is preferable to provide a plurality of second through electrodes 72 connected to the common electrode 49 in order to suppress the resistance of the path connected to the common electrode 49. By making the hole diameter of the second through hole 74 larger than the hole diameter of the first through hole 73, it is possible to reduce the resistance of the path connected to the common electrode 49. However, if the hole diameters of the first through hole 73 and the second through hole 74 are the same as in the present embodiment, it is not necessary to make the mask shape different when forming the respective holes by etching, and the holes are formed. Has the advantage of facilitating.

However, increasing the number of the second through electrodes 72 more than necessary is not preferable from the viewpoint of increasing the size of the piezoelectric actuator 24 and the protective member 26. Therefore, for example, the number and diameter of the second through silicon via 72 may be determined based on the following relational expression.

Here, even if all the piezoelectric elements 41 are driven at the same time and the maximum current flows in the path connected to the common electrode 49, the current exceeding the allowable current value does not flow in the second through electrode 72. , Determine the number and diameter of the second through electrode 72. That is, the maximum amount of current flowing from one piezoelectric element 41 to the common electrode 49 is I, the number of piezoelectric elements 41 connected to the common electrode 49 is n, and the allowable current density of the electrode material constituting the second through electrode 72 is defined. i, when the cross-sectional area of one second through electrode 72 is A and the number of second through electrodes 72 is N,
N> (I × n) / (i × A)
The number and diameter of the second through silicon via 72 are determined so as to satisfy the above relationship.

A specific example of selecting the number of the second through silicon via 72 will be described. First, the maximum current I flowing from one piezoelectric element 41 to the common electrode 49 is 10 mA (= 1.0 × 10 ⁻² A), and the allowable current density i of the copper (Cu) constituting the second through electrode 72 is 0. .5 × 10 ⁴ A / mm ² , the number n of piezoelectric elements 31 (the number of nozzles 36) is 800. In this case, the required number of the second through electrodes 72 varies as follows depending on the diameter d of the through hole 74.

(D = 40 μm)
A = 1.3 × 10 ^-3 mm ² , and N> 1.23. At least two second through electrodes 72 are required.
(D = 30 μm)
A = 7.1 × 10 ^-4 mm ² , and N> 2.25. At least three second through electrodes 72 are required.
(D = 20 μm)
A = 3.1 × 10 ^-4 mm ² , and N> 5.1. At least 6 through silicon vias 72 are required.

The above relational expression indicates the minimum required number of the second through silicon via 72. Therefore, in practice, the number of the second through silicon vias 72 may be increased by one or more from N obtained from the above relational expression in order to provide a margin.

The driver IC 37 is pressed and joined to the individual terminals 65 of the top wall portion 53. In order to prevent the top wall portion 53 from being deformed by the pressing force at the time of joining the driver IC 37, the individual terminal 65 is the left and right end portions of the top wall portion 53 connected to the side wall portion 54, or the partition wall portion 55. It is preferable that it is provided in the central portion connected to. In this embodiment, the individual terminal 65 is arranged at the center of the top wall portion 53.

Further, in the present embodiment, a plurality of first through electrodes 71 are formed on the partition wall portion 55, and the plurality of first through electrodes 71 are conducting with a plurality of individual terminals 65 arranged directly above the partition wall portion 55. In this configuration, since a plurality of first through electrodes 71 drawn out from the two piezoelectric element rows 47 on both sides thereof are centrally arranged on the partition wall portion 55, the piezoelectric actuator 24 and the protective member 26 are arranged in the left-right direction. It is possible to reduce the size of the.

Further, as shown in FIG. 5, the first through electrode 71 and the second through electrode 72 are formed in the central portion in the left-right direction of the partition wall portion 55. In this configuration, even when a pressing force acts on the partition wall portion 55 at the time of joining the driver IC 37, the bending force is less likely to act on the internal through electrodes 71 and 72, so that disconnection in the through electrodes 71 and 72 can be suppressed.

The FPC 27 is pressed and joined to the plurality of input terminals 61 of the top wall portion 53. The input terminal 61 is also provided at a portion of the top wall portion 53 connected to the side wall portion 54 or the partition wall portion 55 in order to prevent the top wall portion 53 from being deformed by the pressing force at the time of joining the FPC 27. Is preferable. In the present embodiment, the plurality of input terminals 61 are formed at the right end portion of the top wall portion 53 connected to the right side wall portion 54.

Next, the manufacturing process of the head unit 16 will be described with reference to FIGS. 9 and 10, focusing on the manufacturing process of the protective member 26 and the bonding process of the protective member 26 with the piezoelectric actuator 24. The following explanatory items (a) to (i) correspond to the items (a) to (i) in FIGS. 9 and 10, respectively.

First, the manufacturing process of the protective member 26 will be described with reference to FIG.
(A) A plurality of concave holes 81 to be the first through holes 73 are formed by etching on the silicon single crystal substrate 80 to be the protective member 26.
(B) The conductive film 82 is formed by sputtering or the like from the side where the hole 81 of the substrate 80 opens. At this time, a part of the conductive material constituting the conductive film 82 enters the hole 81.
(C) The substrate 80 is polished from both sides up to the line of the two alternate long and short dash lines shown in (b), and both ends of the hole 81 are scraped off. As a result, the first through electrode 71 in which the conductive material is filled in the first through hole 73 is formed.

(D) Insulating films 75 and 76 are formed on the lower surface and the upper surface of the polished substrate 80, respectively. Further, the insulating films 75 and 76 are etched to form holes 75a and 76a smaller than the first through holes 71, respectively.
(E) Wiring and terminals such as signal input terminals 62, individual terminals 65, and signal wiring 68 are formed on the upper surface of the substrate 80 by plating with gold (Au) or patterning with a thin film of aluminum (Al).
(F) The recess 83 is formed by etching from the lower side of the substrate 80. This completes the production of the protective member 26 having the top wall portion 53, the two side wall portions 54, and the partition wall portion 55.

Next, with reference to FIG. 10, a process from the joining process of the protective member 26 to the joining of the driver IC 37 and the FPC 27 will be described.
(G) After the conductive adhesive 60 (ACF or ACP) is attached to the lower surface of the protective member 26, the protective member 26 is pressed against the piezoelectric actuator 24 having the piezoelectric element 41 while heating. As a result, the protective member 26 is mechanically joined to the piezoelectric actuator 24 in a state where the drive contact 57 and the first through electrode 71 are electrically connected.

(H) After the first flow path member 21 is thinned to a predetermined thickness by polishing, a pressure chamber 28 is formed in the first flow path member 21 by etching.
(I) The driver IC 37 is joined to the central portion of the top wall portion 53 of the protective member 26 with a conductive adhesive 64. After that, the FPC 27 is joined to the right end portion of the protective member 26 with the conductive adhesive 64. It is also possible to join the driver IC 37 and the FPC 27 at the same time.

In the embodiment described above, the head unit 16 corresponds to the "liquid discharge device" of the present invention. The first flow path member 21 corresponds to the "flow path member" of the present invention. The front-back direction in which the piezoelectric elements 41 are arranged corresponds to the "first direction" of the present invention. The left-right direction parallel to the arrangement surface of the piezoelectric element 41 and orthogonal to the front-rear direction corresponds to the "second direction" of the present invention. The piezoelectric actuator 24 corresponds to the "actuator" of the present invention. The drive contact 57 corresponds to the "first contact" of the present invention, and the ground contact 58 corresponds to the "second contact" of the present invention. The top wall portion 53 of the protective member 26 corresponds to the "first wall portion" of the present invention, and the side wall portion 54 and the partition wall portion 55 correspond to the "second wall portion" of the present invention. The individual terminal 65 formed on the top wall portion 53 is the "first connection terminal" of the present invention, the first ground terminal 67 is the "second connection terminal" of the present invention, and the input terminal 61 is the "third connection terminal" of the present invention. Corresponds to "connection terminal". The insulating film 75 corresponds to the "first insulating film" of the present invention, and the insulating film 76 corresponds to the "second insulating film" of the present invention. The lower electrode 42 of the piezoelectric element 41 corresponds to the "first electrode" of the present invention, and the upper electrode 44 corresponds to the "second electrode" of the present invention. The driver IC 37 corresponds to the "drive circuit" of the present invention. The FPC 27 corresponds to the "wiring member" of the present invention.

Next, a modified embodiment in which various modifications are made to the embodiment will be described. However, those having the same configuration as that of the above-described embodiment are designated by the same reference numerals and the description thereof will be omitted as appropriate.

1] When the first through hole is formed in the protective member by etching, the hole diameter tends to become smaller toward the inner side in the etching progress direction, and the shape tends to be tapered. In this case, as shown in the protective member 26A of FIG. 11, the first through hole 73A is etched from the opposite side (upper side) of the piezoelectric actuator 24A so that the hole diameter becomes smaller toward the piezoelectric actuator 24A side. Is preferable.

As can be seen from FIG. 3 and the like, when the lower drive contact 57 and the upper individual terminal 65 are compared, the upper individual terminal 65 has more space for arrangement. Therefore, the individual terminals 65 tend to have a larger arrangement interval than the drive contacts 57. Conversely, since it is difficult to increase the arrangement spacing of the drive contacts 57, it is preferable to reduce the diameter of the first through electrode 71A toward the lower side in order to surely prevent a short circuit on the lower end side.

2] One or both of the insulating film 75 covering the lower end surface and the insulating film 76 covering the upper end surface of the first through silicon via 71 shown in FIGS. 5 and 6 of the above embodiment may be omitted. In FIG. 12, the insulating film is not formed on both the lower surface and the upper surface of the protective member 26B. In particular, when the area of the lower end surface of the first through electrode 71B is smaller than the area of the drive contact 57, the insulating film 75 may be omitted. Further, when the area of the upper end surface of the first through electrode 71B is smaller than the area of the individual terminal 65, the insulating film 76 may be omitted.

3] In the above embodiment (see FIG. 3), the first ground terminal 67 connected to the common electrode 49 and the second ground terminal 67 connected to the driver IC 37 as ground terminals on the upper surface of the top wall portion 53 of the protective member 26. Although the ground terminal 70 is provided, these two types of ground terminals may be combined into one.

For example, in the head unit 16C of FIG. 13, two ground terminals 67C are arranged on both front and rear sides of the plurality of individual terminals 65. The ground terminal 67C is connected to the ground input terminal 63 by a ground wiring 69C formed on the upper surface of the top wall portion 53 of the protective member 26. Further, the ground terminal 67C is connected to the common electrode via the second through electrode 72C formed on the protective member 26. Further, the ground terminal 67C is also connected to the driver IC 37C. In the configuration of FIG. 13, as compared with FIG. 3, the ground wiring is simplified and the wiring can be easily routed. Further, since the number of terminals on the top wall portion 53 is reduced, the protective member 26 can be miniaturized.

4] In the above embodiment, as shown in FIG. 5, the driver IC 37 is arranged at the center in the left-right direction connected to the partition wall portion 55 of the top wall portion 53, and is connected to the side wall portion 54 of the top wall portion 53. The FPC27 is joined to the directional end. On the other hand, both the driver IC 37 and the FPC 27 may be arranged in a portion of the top wall portion 53 connected to one side wall portion 54 or the partition wall portion 55.

For example, in the head unit 16D of FIGS. 14 and 15, individual terminals 65D and signal terminals 66D are arranged in the left half of the central portion of the top wall portion 53, which is a connecting portion connected to the partition wall portion 55, and the signal terminals 66D are arranged in the right half. The input terminal 61D is arranged. A driver IC 37 is arranged in the left half of the central portion of the top wall portion 53, and is connected to the individual terminal 65D and the signal terminal 66D. Further, the FPC 27 is joined to the right half of the central portion of the top wall portion 53 and is connected to the input terminal 61D. Further, the first through electrode 71D connected to the individual terminal 65D is also located in the left half of the partition wall portion 55. That is, the driver IC 37, the individual terminal 65D, the signal terminal 66D, and the first through silicon via 71D are arranged so as to be offset to the left side with respect to the central portion of the partition wall portion 55.

As described above, when the individual terminal 65D and the signal terminal 66D connected to the driver IC 37 and the input terminal 61D connected to the FPC 27 are arranged in the central portion of the top wall portion 53, the embodiment (FIG. 3). ), The length of the signal wiring 68D connecting the driver IC 37 (signal terminal 66D) and the input terminal 61D can be shortened.

Since the signal wiring 68D is located on the surface of the top wall portion 53 of the protective member 26 and is exposed at least during manufacturing, the longer the wiring, the more likely it is that problems such as disconnection will occur during the manufacturing process. In addition, when the protective member expands and contracts or deforms due to factors such as changes in the external environment (temperature and humidity), if the wiring is long, adverse effects such as poor continuity, short circuit, and increase / decrease in wiring resistance may occur. In these respects, the above configuration that can shorten the length of the signal wiring 68D is advantageous.

5] In the above embodiment, as shown in FIG. 5, the driver IC 37 is arranged at the connecting portion of the top wall portion 53 with the partition wall portion 55 on which the first through electrode 71 is formed. On the other hand, as in the head unit 16E of FIG. 16, COF (Chip ON Film), which is a wiring member in which the driver IC 87 is mounted on the connecting portion of the top wall portion 53 of the protective member 26 with the partition wall portion 55. 90 may be joined. The driver IC 87 is electrically connected to the individual terminal 65 and outputs a drive signal to the piezoelectric element 41. In the above embodiment, since the driver IC 37 and the FPC 27 are bonded to the protective member 26, two electrical connection steps are required. However, in FIG. 16, only the COF 90 is bonded to the protective member 26, which is electrical. The number of connection steps can be reduced.

6] The protective member 26 of the embodiment covers the two piezoelectric element rows 47, and in addition to the top wall portion 53 and the two side wall portions 54, the partition wall portion 55 that partitions between the two piezoelectric element rows 47 is provided. However, as shown in FIG. 17, the protective member 26F may cover only one piezoelectric element row 47. That is, the protective member 26F includes only the top wall portion 53F and the two side wall portions 54Fa and 54Fb, and does not include the partition wall portion. A first through electrode 71 is formed on the side wall portion 54F on the left side of the protective member 26F. The driver IC 37 is arranged at the left end of the top wall portion 53F connected to the side wall portion 54F. Further, the FPC 27 is joined to the right end portion of the top wall portion 53F connected to the right side wall portion 54Fb.

Further, in the configuration as shown in FIG. 17, the distance between the two adjacent first through electrodes 71 may be widened as follows. For example, in FIG. 18, a plurality of drive contacts 57 are respectively drawn to the right from a plurality of piezoelectric elements 41 belonging to one piezoelectric element row 47. However, the plurality of drive contacts 57 are not arranged in a row in the front-rear direction, but are arranged in a staggered pattern to form two contact rows 56F. Along with this, a plurality of first through electrodes 71 are also arranged in a staggered pattern to form two electrode rows 77F. In this configuration, the distance P2F between the two first through electrodes 71 adjacent to each other in the front-rear direction is larger than the distance P1F in the front-rear direction of the two corresponding piezoelectric elements 41. This makes it possible to prevent a short circuit between two adjacent first through silicon vias 71.

Further, in FIG. 19, a plurality of drive contacts 57G drawn to the right from the plurality of piezoelectric elements 41 belonging to one piezoelectric element row 47 are arranged in one row. However, the plurality of drive contacts 57G are arranged so as to spread radially as a whole. As a result, the arrangement spacing P2G in the front-rear direction of the first through electrode 71 corresponding to the piezoelectric element 41 belonging to one piezoelectric element row 47 is larger than the arrangement spacing P1G in the front-back direction of the piezoelectric element 41 of one piezoelectric element row 47. Is also getting bigger. This makes it possible to prevent a short circuit between two adjacent first through silicon vias 71.

7] In the above embodiment, as shown in FIGS. 5 and 6, the driver IC 37 is arranged at the connecting portion of the top wall portion 53 with the partition wall portion 55 on which the first through electrode 71 is formed. It is not essential that the IC 37 is directly above the first through silicon via 71, and the driver IC 37 may be located away from the first through silicon via 71. In that case, the individual terminal 65 located directly above the first through electrode 71 and the driver IC 37 are connected by wiring formed on the top wall portion 53.

8] The arrangement of the drive contacts of the piezoelectric actuator is not limited to the configuration of the above embodiment. The drive contacts of all the piezoelectric elements may be drawn out in the same direction, and all the drive contacts may be arranged in a row at one end of the piezoelectric actuator. Alternatively, wiring may be drawn out from each of the two piezoelectric element trains on both sides in the scanning direction, and drive contacts may be arranged at both ends of the piezoelectric actuator in the scanning direction.

In particular, the arrangement of through electrodes, terminals, wiring, and the like of the protective member when the drive contacts are pulled out from the two piezoelectric element rows in the left-right direction will be described with reference to FIG. In the head unit 16H of FIG. 20, the two left and right side wall portions 54H of the protective member 26H are joined to the left and right end portions of the piezoelectric actuator in which the drive contacts are arranged. On top of that, a plurality of first through silicon vias 71H and two second through silicon vias 72H are formed on each side wall portion 54H. Further, each of the left end portion and the right end portion of the top wall portion 53H connected to the side wall portion 54H has a plurality of individual terminals 65H conducting with a plurality of first through electrodes 71H and two second through electrodes 72H. Two conductive ground terminals 67H are formed.

The driver IC 37H is arranged at the center of the top wall portion 53H in the left-right direction connected to the partition wall portion 55H. The driver IC 37H is connected to the individual terminals 65H arranged at the left end and the right end of the top wall portion 53H by the individual wiring 68H, and is connected to the ground terminal 67H by the ground wiring 69H.

In the configuration of FIG. 20, since the rows of the two first through electrodes 71H corresponding to the two piezoelectric element rows are separately arranged in the two left and right side wall portions 54H, the front-rear direction is compared with that of FIG. 7 of the embodiment. The distance between the first through electrodes 71 adjacent to the can be increased. In FIG. 20, instead of arranging the driver IC 37H directly above the partition wall portion 55H, a wiring member (COF) on which the driver IC is mounted may be joined.

9] In the above embodiment, the protective member 26 is bonded to the piezoelectric actuator 24 with the conductive adhesive 60, but it may be bonded with the non-conductive adhesive (NCF or NCP).

10] The inkjet head 4 of the embodiment is a so-called serial type head that ejects ink while moving in the width direction of the recording paper 100, but is a so-called line type head having nozzles arranged in the paper width direction. The present invention can be similarly applied to the head.

The embodiments described above apply the present invention to an inkjet head that ejects ink onto recording paper to print an image or the like, but the present invention applies to all actuator devices used for applications other than liquid ejection. Is also applicable. Further, the actuator is not limited to the piezoelectric actuator composed of a plurality of piezoelectric elements. For example, as the driving element, an actuator having a heating element that drives the target by utilizing the heat generated when a current is passed may be used.

16 Head unit 21 Flow path member 24 Piezoelectric actuator 25 Actuator device 26 Protective member 27 FPC
28 Pressure chamber 36 Nozzle 37 Driver IC
41 Piezoelectric element 42 Lower electrode 44 Upper electrode 47 Piezoelectric element row 49 Common electrode 53 Top wall part 54 Side wall part 55 Partition part 56 Contact row 57 Drive contact 58 Ground contact 60 Adhesive 60 Conductive adhesive 61 Input terminal 65 Individual terminal 67 Ground terminal 68 Signal wiring 69 Ground wiring 71 1st through electrode 72 2nd through electrode 73 1st through hole 74 2nd through hole 75 Insulation film 76 Insulation film 77 Electrode row 87 Driver IC

Claims (9)

An actuator having a plurality of piezoelectric elements arranged in the first direction and a plurality of first contacts drawn from the plurality of piezoelectric elements and arranged along the first direction.
The second wall portion has a first wall portion facing the piezoelectric element and a second wall portion connected to the first wall portion, and the second wall portion covers the piezoelectric element, and the second wall portion is the first contact point of the actuator. With the protective member joined to the placement area of
A plurality of first connection terminals arranged on the surface of the first wall portion of the protective member opposite to the actuator, and
A plurality of first through electrodes provided in the plurality of first through holes formed in the second wall portion of the protective member, each of which is conductive to the first contact and the first connection terminal. , Equipped with
The distance between the two first through electrodes corresponding to the two adjacent piezoelectric elements in the first direction is larger than the distance between the two adjacent piezoelectric elements in the first direction.
The plurality of first through electrodes extend in the first direction and are arranged in a second direction parallel to the arrangement surface of the piezoelectric element and orthogonal to the first direction. Configure and
The position of the first through electrode is displaced in the first direction between the first electrode row and the second electrode row.
The distance between the first through electrode belonging to the first electrode row and the first through electrode belonging to the second electrode row in the direction connecting the centers of the two in a straight line corresponds to these two first through electrodes. Greater than the distance between the two piezoelectric elements in the first direction,
The first through electrode belonging to the first electrode row is arranged on one side of the piezoelectric element corresponding to the first through electrode in the second direction.
The first through electrode belonging to the second through electrode row is arranged on the other side of the piezoelectric element corresponding to the first through electrode in the second direction.
The first through electrode belonging to the first electrode row and the first through electrode belonging to the second electrode row are alternately arranged at equal intervals along the first direction in a staggered pattern.
The piezoelectric element has a piezoelectric film and a first electrode and a second electrode that sandwich the piezoelectric film in the thickness direction thereof.
The first electrodes are separated from each other among the plurality of piezoelectric elements, and the second electrodes are electrically connected to each other to form a common electrode.
The first contact is connected to the first electrode and is connected to the first electrode.
The actuator has a second contact connected to the common electrode.
A second connection terminal arranged on the surface of the first wall portion of the protective member opposite to the actuator,
A second through electrode provided in the second through hole formed in the second wall portion of the protective member and conducting with the second contact and the second connection terminal.
An actuator device characterized by being further equipped with. The actuator has a plurality of the second contacts.
A plurality of the second connection terminals are provided on the first wall portion of the protective member.
A claim characterized in that a plurality of the second through electrodes for conducting the plurality of second contacts and the plurality of second connection terminals are provided on the second wall portion of the protective member. Item 1. The actuator device according to item 1. The maximum amount of current flowing from one piezoelectric element to the common electrode is I, the number of piezoelectric elements connected to the common electrode is n, and the allowable current density of the electrode material constituting the second through electrode is i. When the cross-sectional area of one second through electrode is A and the number of the second through electrodes is N,
N> (I × n) / (i × A)
The actuator device according to claim 1, wherein the relationship is satisfied. The actuator device according to any one of claims 1 to 3, wherein the hole diameter of the first through hole and the hole diameter of the second through hole of the second wall portion of the protective member are the same. The protective member is provided on the joint surface of the second wall portion of the second wall portion with the actuator so as to cover the end surface of the first through electrode on the actuator side, and is smaller than the end surface of the first through electrode on the actuator side. The actuator device according to any one of claims 1 to 4, wherein the actuator device has a first insulating film having holes formed therein. The actuator device according to claim 5, wherein the area of the end face of the first through electrode on the actuator side is larger than the area of the first contact. The protective member is provided on the surface of the first wall portion on the side opposite to the actuator so as to cover the end surface of the first through electrode opposite to the actuator, and is opposite to the actuator of the first through electrode. The actuator device according to any one of claims 1 to 6, wherein the actuator device has a second insulating film in which a hole smaller than the end face on the side is formed. The actuator device according to any one of claims 1 to 7, wherein the first through hole of the protective member is formed in a tapered shape in which the hole diameter becomes smaller toward the actuator side. The actuator device according to any one of claims 1 to 8, wherein the protective member is made of silicon.

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