JP2020196230A - Liquid discharge head - Google Patents

Abstract

To provide a liquid discharge head which can be reduced in size in the direction orthogonal to the array direction of a pressure chamber as a whole.SOLUTION: A head unit 25 comprises: a nozzle plate 30 which has an ink discharge surface 30a on which a nozzle 31 is opened, and is formed with a driver 32; a pressure chamber formation plate 40 which has a surface 41b opposite to the nozzle plate 30 and is formed with a pressure chamber 43 communicating to the nozzle 31; and a piezoelectric element 50 which is formed on a surface 41b opposite to the nozzle plate 30 of the pressure chamber formation plate 40. The nozzle plate 30 is joined to the surface 41b opposite to the nozzle plate 30 of the pressure chamber formation plate 40 such that the driver 32 and the piezoelectric element 50 overlap each other in the direction orthogonal to the ink discharge surface 30a.SELECTED DRAWING: Figure 3

Description

The present invention relates to a liquid ejection head that ejects ink from a nozzle.

Conventionally, a region facing the pressure generating chamber via a nozzle plate on which a nozzle is formed, a flow path forming substrate in which a pressure generating chamber communicating with the nozzle is defined, and a diaphragm forming a part of the pressure generating chamber. An inkjet recording head including a piezoelectric element provided in is known (see Patent Document 1). In this inkjet recording head, a diaphragm is provided between the nozzle plate and the flow path forming substrate. That is, the nozzle plate is joined to the surface of the diaphragm on the side where the piezoelectric element is provided. A recess is formed in the region of the nozzle plate facing the diaphragm, which faces the piezoelectric element, so as not to hinder the driving of the piezoelectric element. Further, a drive IC for driving the piezoelectric element is formed in a portion joined to the diaphragm of the flow path forming substrate and different from the pressure chamber.

Japanese Unexamined Patent Publication No. 2001-205808

In the above-mentioned inkjet recording head, since the piezoelectric element and the drive IC are arranged apart from each other in the direction orthogonal to the arrangement direction of the pressure chamber (longitudinal direction of the pressure chamber), the entire inkjet recording head has the pressure chamber. There is a problem that the size in the direction orthogonal to the arrangement direction becomes large.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide a liquid discharge head capable of reducing the size in the direction orthogonal to the arrangement direction of the pressure chamber as a whole.

According to the aspect of the present invention, a nozzle substrate having a nozzle surface through which the nozzle opens and a driver is formed, and a first surface facing the nozzle substrate, and a flow path communicating with the nozzle is formed. The flow path substrate is provided with a piezoelectric element formed on the first surface of the flow path substrate, and the nozzle substrate overlaps the driver and the piezoelectric element in a first direction orthogonal to the nozzle surface. As described above, the liquid discharge head bonded to the first surface of the flow path substrate is provided.

It is a schematic plan view of the printer which concerns on 1st Embodiment. It is a bottom view of the head unit which concerns on 1st Embodiment. FIG. 2 is a sectional view taken along line III-III of FIG. It is a figure which shows a part of the manufacturing process of the head unit which concerns on 1st Embodiment. It is a figure which shows a part of the manufacturing process of the head unit which concerns on 1st Embodiment, and shows the process which follows the process shown in FIG. It is a figure which shows a part of the manufacturing process of the head unit which concerns on 1st Embodiment, and shows the process which follows the process shown in FIG. It is a figure which shows a part of the manufacturing process of the head unit which concerns on 2nd Embodiment. It is a figure which shows a part of the manufacturing process of the head unit which concerns on 2nd Embodiment, and shows the process which follows the process shown in FIG. It is a figure which shows a part of the manufacturing process of the head unit which concerns on 2nd Embodiment, and shows the process which follows the process shown in FIG.

<First Embodiment>
The first embodiment of the present invention will be described. First, a schematic configuration of the inkjet printer 1 will be described with reference to FIG. The front, back, left, and right directions shown in FIG. 1 are defined as "front", "rear", "left", and "right" of the printer. Further, the front side of the paper surface in FIG. 1 is defined as "upper", and the other side of the paper surface is defined as "lower". In the following, each direction word of front, back, left, right, up and down will be described as appropriate.

<Outline configuration of printer>
As shown in FIG. 1, the inkjet printer 1 mainly includes a platen 2, a carriage 3, an inkjet head 4, a transport mechanism 5, and a controller 6.

A recording sheet 100, which is a recording medium, is placed on the upper surface of the platen 2. The carriage 3 is configured to be reciprocally movable in the left-right direction (hereinafter, also referred to as a scanning direction) along the two guide rails 11 and 12 in the region facing the platen 2. An endless belt 13 is connected to the carriage 3. By driving the endless belt 13 by the carriage drive motor 14, the carriage 3 moves 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 25 (an example of the liquid ejection head of the present invention) arranged in the scanning direction. The four head units 25 are connected to a cartridge holder 7 to which the four ink cartridges 15 are mounted by a tube (not shown). Ink of four colors (black, yellow, cyan, magenta) is stored in each of the four ink cartridges 15. Each head unit 25 has a plurality of nozzles 31 (see FIG. 2) formed on the lower surface thereof (the surface on the other side of the paper surface in FIG. 1). The nozzle 31 of the head unit 25 ejects one color of ink supplied from any one of the ink cartridges 15 toward the recording paper 100 mounted on the platen 2.

The transport mechanism 5 has two transport rollers 16 and 17 arranged so as to sandwich the platen 2 in the front-rear direction. The transport mechanism 5 transports the recording paper 100 mounted on the platen 2 forward (hereinafter, also referred to as a transport direction) by the two transport rollers 16 and 17.

The controller 6 includes a ROM (Read Only Memory), a RAM (Random Access Memory), an ASIC (Application Specific Integrated Circuit) including various control circuits, and the like. The controller 6 executes various processes such as printing on the recording paper 100 by the ASIC according to the program stored in the ROM. For example, in the printing process, the controller 6 controls a transfer motor (not shown) of the inkjet head 4, the carriage drive motor 14, and the transfer mechanism 5 based on a print command input from an external device such as a PC. An image or the like is printed on the recording paper 100. Specifically, the ink ejection operation of ejecting ink from the nozzles 31 of the four head units 25 while moving the inkjet head 4 together with the carriage 3 in the scanning direction, and the conveying rollers 16 and 17 move the recording paper 100 in the conveying direction. The transport operation of transporting a predetermined amount is alternately performed.

<Head unit 25>
Next, the configuration of the head unit 25 will be described in detail. Since each of the four head units 25 has the same configuration, one of the four head units 25 will be described below.

As shown in FIG. 2, the head unit 25 has a substantially rectangular outer shape that is long in the transport direction in a plan view. As shown in FIG. 3, the head unit 25 mainly includes a nozzle plate 30 (an example of a nozzle substrate of the present invention), a pressure chamber forming plate 40 (an example of a flow path substrate of the present invention), a piezoelectric element 50, and a throttle flow. It is composed of a path forming plate 60 and a manifold flow path forming plate 70.

As shown in FIG. 2, the nozzle plate 30 has a substantially rectangular outer shape that is long in the transport direction in a plan view. The nozzle plate 30 is a silicon substrate. Discharge ports and drivers 32 for a plurality of nozzles 31 are formed on the lower surface of the nozzle plate 30. In the following description, the region on the lower surface of the nozzle plate 30 where the ejection ports of the plurality of nozzles 31 are formed is referred to as an ink ejection surface 30a (an example of the nozzle surface of the present invention). On the ink ejection surface 30a, the plurality of nozzles 31 form a nozzle row 31a extending in the transport direction. The driver 32 has a substantially rectangular outer shape that is long in the transport direction in a plan view. On the ink ejection surface 30a, the nozzle row 31a and the driver 32 are adjacent to each other in the scanning direction.

As shown in FIG. 3, each nozzle 31 penetrates the nozzle plate 30 in the thickness direction thereof. Further, the driver 32 is integrally formed with the nozzle plate 30 so as to be flush with the ink ejection surface 30a. Further, a recess 33 is formed on the surface 30b of the nozzle plate 30 opposite to the ink ejection surface 30a, that is, the surface 30b facing the pressure chamber forming plate 40, in a region facing the piezoelectric element 50. .. Further, a plurality of through electrodes 34 extending in the thickness direction of the nozzle plate 30 are formed in a portion of the nozzle plate 30 where the nozzle 31 and the recess 33 are not formed and which overlaps with the driver 32. The through electrode 34 is made of, for example, copper (Cu). One end of the through electrode 34 is connected to the driver 32. The other end of the through electrode 34 is exposed on the surface 30b of the nozzle plate 30 opposite to the ink ejection surface 30a. Further, an electrode pad 35 is formed on the surface 30b of the nozzle plate 30 opposite to the ink ejection surface 30a at a position overlapping the through electrode 34. The electrode pad 35 is in contact with the other end of the through electrode 34.

The pressure chamber forming plate 40 has a substantially rectangular outer shape that is long in the transport direction in a plan view. As shown in FIG. 2, the pressure chamber plate 40 is formed with a plurality of pressure chambers 43 (an example of a flow path of the present invention) communicating with a plurality of nozzles 31. The plurality of pressure chambers 43 are arranged in the transport direction so as to overlap each of the plurality of nozzles 31. Each pressure chamber 43 has a substantially rectangular outer shape that is long in the scanning direction in a plan view. As shown in FIG. 3, the pressure chamber forming plate 40 includes a diaphragm 41 and a pressure chamber substrate 42. The diaphragm 41 is an insulating layer formed by, for example, oxidizing or nitriding the surface of the silicon substrate constituting the pressure chamber substrate 42, and is arranged on substantially the entire surface of the pressure chamber substrate 42.

A plurality of through holes 41a are formed in the portion of the diaphragm 41 that overlaps with the plurality of nozzles 31. The pressure chamber substrate 42 is formed with through holes that define the side walls of each pressure chamber 43.

On the surface 41b (an example of the first surface of the present invention) of the diaphragm 41 opposite to the plurality of pressure chambers 43, a plurality of piezoelectric elements 50 (piezoelectric actuators of the present invention) facing the plurality of pressure chambers 43, respectively. An example) is formed. As shown in FIG. 2, the plurality of piezoelectric elements 50 are arranged in the transport direction so as to overlap the plurality of pressure chambers 43, respectively. Further, the plurality of piezoelectric elements 50 overlap the driver 32 in a direction orthogonal to the ink ejection surface 30a (an example of the first direction of the present invention). The total area of the plurality of piezoelectric elements 50 is equal to or less than the area of the driver 32. As shown in FIG. 3, each piezoelectric element 50 is composed of a common electrode 51, a piezoelectric layer 52, and individual electrodes 53. The piezoelectric layer 52 is sandwiched between the common electrode 51 and the individual electrode 53.

The common electrode 51 is commonly provided in the plurality of piezoelectric elements 50, and extends in the transport direction so as to overlap the plurality of pressure chambers 43. The common electrode 51 is made of, for example, platinum (Pt).

The piezoelectric layer 52 is also provided in common with the plurality of piezoelectric elements 50, and extends in the transport direction so as to overlap the common electrode 51. The piezoelectric layer 52 is made of, for example, a piezoelectric material containing lead zirconate titanate (PZT), which is a mixed crystal of lead titanate and lead zirconate, as a main component.

One individual electrode 53 is provided for each piezoelectric element 50. That is, a plurality of individual electrodes 53 are provided for each of the plurality of piezoelectric elements 50. As shown in FIG. 2, the plurality of individual electrodes 53 are arranged in the transport direction so as to overlap the plurality of pressure chambers 43, respectively. Each individual electrode 53 has a substantially rectangular outer shape that is long in the scanning direction in a plan view. Each individual electrode 53 is made of, for example, iridium (Ir).

The portion of the piezoelectric layer 52 sandwiched between the individual electrode 53 and the common electrode 51 functions as an active portion that can be deformed in response to application of a voltage to the individual electrode 53. That is, each piezoelectric element 50 has an active portion facing the corresponding pressure chamber 43. By driving the active portion (for example, deforming so as to be convex toward the pressure chamber 43) in response to the application of a voltage to the individual electrodes 53, the volume of the pressure chamber 43 changes, and the pressure chamber 43 changes. Pressure is applied to the ink inside, and the ink is ejected from the nozzle 31.

As shown in FIGS. 2 and 3, an individual wiring 54 is connected to the left end of each individual electrode 53. The individual wiring 54 extends to the left along the scanning direction. The individual wiring 54 and the common electrode 51 are insulated by an insulating film (not shown). A terminal 54a is provided at the end of the individual wiring 54 on the side opposite to the individual electrode 53. Further, as shown in FIG. 2, two common wirings 55 are connected to both ends of the common electrode 51 in the transport direction. Each common wiring 55 extends from the common electrode to the left along the scanning direction. Terminals are provided at the ends of the common wiring 55 on the opposite side of the common electrode 51. The terminals of the individual wiring 54, the terminals 54a, the common wiring 55, and the common wiring 55 are made of, for example, aluminum (Al).

Then, as shown in FIG. 3, the nozzle plate 30 and the pressure chamber forming plate 40 are formed by bumps 80 on one side (left side in FIG. 3) and the other side (right side in FIG. 3) in the scanning direction. It is joined. The bump 80 is made of, for example, an anisotropic conductive paste. Specifically, on one side in the scanning direction, a plurality of electrode pads 35 provided on the surface 30b of the nozzle plate 30 opposite to the ink ejection surface 30a are common to the terminals 54a of the corresponding individual wiring 54, respectively. It is joined to the terminal of the wiring 55 via a plurality of bumps 80. As a result, the plurality of electrode pads 35 are electrically connected to the individual wiring 54 and the common wiring 55. Further, on the other side in the scanning direction, the periphery of the plurality of nozzles 31 and the periphery of the plurality of through holes 41a formed in the diaphragm 41 are joined via the plurality of annular bumps 80. As a result, the plurality of nozzles 31 and the plurality of pressure chambers 43 are in communication with each other.

As shown in FIG. 3, the ink ejection surface 30a, the inner wall of each nozzle 31, the inner wall of each annular bump 80, and the inner wall of each through hole 41a are covered with a protective film 90. Further, in a state where the nozzle plate 30 and the pressure chamber forming plate 40 are joined, each piezoelectric element 50 faces the recess 33 formed on the surface 30b of the nozzle plate 30 opposite to the ink ejection surface 30a. Therefore, the drive of each piezoelectric element 50 is not hindered.

The throttle flow path forming plate 60 has a substantially rectangular outer shape that is long in the transport direction in a plan view. The throttle flow path forming plate 60 is a silicon substrate. The throttle flow path forming plate 60 is formed with a plurality of throttle flow paths 61 that communicate with each of the plurality of pressure chambers 43. Each throttle flow path 61 penetrates the throttle flow path forming plate 60 at a position overlapping the corresponding pressure chamber 43.

The manifold flow path forming plate 70 has a substantially rectangular outer shape that is long in the transport direction in a plan view. The manifold flow path forming plate 70 is a silicon substrate. The manifold flow path forming plate 70 is formed with a manifold 71 that communicates with a plurality of throttle flow paths 61. The manifold 71 extends in the transport direction so as to overlap the plurality of throttle flow paths 61. The ink supplied from the ink cartridge 15 to the manifold 71 via a tube (not shown) is supplied to the plurality of pressure chambers 43 via the plurality of throttle flow paths 61.

<Manufacturing process of head unit 25>
Next, among the manufacturing steps of the head unit 25, the main steps in the present invention will be described with reference to FIGS. 4 to 6.

First, as shown in FIG. 4A, a semiconductor process (deposition, exposure, development, etching, etc.) generally performed on the surface of the silicon substrate 30'that becomes the nozzle plate 30 that becomes the ink ejection surface 30a). The driver 32 is formed by Next, as shown in FIG. 4B, the silicon substrate 30'is polished from the side opposite to the surface to be the ink ejection surface 30a until the thickness becomes 30 to 50 μm.

Next, as shown in FIG. 4C, after forming a plurality of through electrodes 34 on the silicon substrate 30', the surface of the silicon substrate 30'on the side opposite to the surface to be the ink ejection surface 30a is formed. The electrode pad 35 is formed. Next, as shown in FIG. 4D, half-etching is performed on a portion of the silicon substrate 30'that is different from the portion where the plurality of through electrodes 34 are formed from the side opposite to the surface that becomes the ink ejection surface 30a. As a result, the recess 33 is formed. Then, as shown in FIG. 4 (e), the nozzle plate 30 is manufactured by forming a plurality of nozzles 31 on the silicon substrate 30'by etching.

Next, as shown in FIG. 5A, the nozzle plate 30 and the silicon substrate 40'which becomes the pressure chamber forming plate 40 are joined by the bump 80. The silicon substrate 40'that serves as the pressure chamber forming plate 40 is manufactured in advance by the following procedure. That is, after forming an insulating layer 41'which becomes a diaphragm 41 by oxidizing or nitriding the surface of the silicon substrate 40', a plurality of piezoelectric elements 50, various wirings 54, 55, and a plurality of wirings 54, 55 are formed on the insulating layer 41'. A through hole 41a'is formed.

Next, as shown in FIG. 5B, the ink ejection surface 30a of the nozzle plate 30, the inner walls of the plurality of nozzles 31, the inner walls of the plurality of annular bumps 80, and the plurality of through holes 41a'of the insulating layer 41'. A protective film 90 made of, for example, alumina (Al ₂ O ₃ ) is formed on the inner wall and the portion of the insulating layer 41'exposed from the plurality of through holes 41a'. The protective film 90 is formed by atomic layer deposition (atomic layer deposition) and has a thickness of about 50 to 100 nm.

Next, as shown in FIG. 5C, by etching the silicon substrate 40'from the surface opposite to the nozzle plate 30, the diaphragm 41, the plurality of through holes 41a, and the plurality of pressures are formed. A plurality of through holes 43'that serve as chambers 43 are formed. As a result, the pressure chamber forming plate 40 is manufactured.

Next, as shown in FIG. 6A, the throttle flow path forming plate 60 is joined to the surface of the pressure chamber forming plate 40 opposite to the diaphragm 41. A plurality of throttle flow paths 61 are formed in advance on the throttle flow path forming plate 60. By joining the throttle flow path forming plate 60 to the pressure chamber forming plate 40, a plurality of pressure chambers 43 are defined, and the plurality of throttle flow paths 61 communicate with each of the plurality of pressure chambers 43. The throttle flow path forming plate 60 and the pressure chamber forming plate 40 are joined by, for example, an epoxy adhesive or direct bonding.

Next, as shown in FIG. 6B, the manifold flow path forming plate 70 is joined to the surface of the throttle flow path forming plate 60 opposite to the pressure chamber forming plate 40. A manifold 71 is formed in advance on the manifold flow path forming plate 70, and the manifold 71 is communicated with a plurality of drawing flow paths 61 by joining the manifold flow path forming plate 70 to the drawing flow path forming plate 60. To do. The manifold flow path forming plate 70 and the drawing flow path forming plate 60 are joined by, for example, an epoxy adhesive.

According to the first embodiment of the present invention described above, the direction in which the driver 32 formed on the nozzle plate 30 and the plurality of piezoelectric elements 50 formed on the pressure chamber forming plate 40 are orthogonal to the ink ejection surface 30a. The nozzle plate 30 and the pressure chamber forming plate 40 are joined so as to overlap with each other. As a result, the size of the head unit 25 in the scanning direction can be reduced as compared with the case where the plurality of piezoelectric elements 50 are arranged so as not to overlap the driver 32 in the direction orthogonal to the ink ejection surface 30a. .. Further, the distance between the driver 32 and the plurality of piezoelectric elements 50 can be shortened, and the wiring length can be shortened. This can reduce the possibility of disconnection.

Further, since the driver 32 is formed on the nozzle plate 30 instead of the pressure chamber forming plate 40 on which the plurality of pressure chambers 43 and the plurality of piezoelectric elements 50 are formed, the size of the pressure chamber forming plate 40 in the scanning direction can be increased. It can be made smaller, and as a result, the size of the head unit 25 in the scanning direction can also be made smaller.

Further, the driver 32 is electrically connected to the plurality of terminals of the various wirings 54 and 55 via the plurality of through electrodes 34 and the plurality of electrode pads 35 formed on the nozzle plate 30 and the plurality of conductive bumps 80. There is. Therefore, a wiring member such as an FPC for connecting the driver 32 and the plurality of terminals of the various wirings 54 and 55 is unnecessary, and the size of the head unit 25 in the scanning direction can be reduced.

Further, on the inner wall of the nozzle 31, a protective film 90 is formed before forming a plurality of through holes 43'in the silicon substrate 40'which becomes the pressure chamber forming plate 40. Therefore, it is possible to prevent the inner wall of the nozzle 31 from being damaged when a plurality of through holes 43'are formed in the silicon substrate 40'by etching.

Further, the total area of the plurality of piezoelectric elements 50 is equal to or less than the area of the driver 32. Therefore, the area of the pressure chamber forming plate 40 can be made as small as the area of the nozzle plate 30, and as a result, the number of pressure chamber forming plates 40 that can be manufactured from one silicon wafer can be increased. ..

<Second Embodiment>
Next, the second embodiment of the present invention will be described. The second embodiment is the same as the first embodiment except for the configuration of the head unit. Therefore, in the following, the head unit 125 according to the second embodiment is different from the head unit 25 according to the first embodiment. Will be mainly explained.

As shown in FIG. 9B, in the head unit 125 according to the second embodiment, the driver 32 is not on the ink ejection surface 130a side of the nozzle plate 130, but on the surface 130b opposite to the ink ejection surface 130a. It is formed. In other words, the driver 32 is formed on the surface 130b of the nozzle plate 130 facing the pressure chamber forming plate 40. The driver 32 is connected to the plurality of terminals of the various wirings 54 and 55, respectively, via the plurality of electrode pads 35 and the plurality of conductive bumps 80. That is, the nozzle plate 130 is not formed with the plurality of through electrodes 34 according to the first embodiment. Further, the recess 33 of the first embodiment is not formed on the surface 130b of the nozzle plate 130 facing the pressure chamber forming plate 40. Therefore, the bump 80 is formed to be higher than each piezoelectric element 50 so as not to hinder the driving of the plurality of piezoelectric elements 50. In other words, the thickness of each bump 80 is thicker than the thickness of each piezoelectric element 50 in the direction orthogonal to the ink ejection surface 130a.

Next, among the manufacturing steps of the head unit 125 according to the second embodiment, the main steps in the present invention will be described with reference to FIGS. 7 to 9.

First, as shown in FIG. 7A, the driver 32 and the plurality of electrode pads 35 are attached to the surface 130b of the silicon substrate 130'which becomes the nozzle plate 130, which is opposite to the surface which becomes the ink ejection surface 130a. Form. Then, as shown in FIG. 7B, the surface 130b of the silicon substrate 130', which is opposite to the surface to be the ink ejection surface 130a, is directed to the silicon substrate 40'to be the pressure chamber forming plate 40. , The silicon substrate 130'and the silicon substrate 40' are joined by a plurality of bumps 80.

Subsequently, as shown in FIG. 7 (c), the silicon substrate 130'is polished from the surface side to be the ink ejection surface 130a until the thickness becomes 30 to 50 μm, and then as shown in FIG. 7 (d). Etching is performed from the surface side that becomes the ink ejection surface 130a to form a plurality of nozzles 31. As a result, the nozzle plate 130 is formed.

Next, as shown in FIG. 8A, the ink ejection surface 130a of the nozzle plate 130, the inner walls of the plurality of nozzles 31, the inner walls of the plurality of annular bumps 80, and the plurality of through holes 41a'of the insulating layer 41'. A protective film 90 having a film thickness of about 50 to 100 nm is formed on the inner wall and the portion of the insulating layer 41'exposed from the plurality of through holes 41a' by atomic layer deposition. After that, by etching the silicon substrate 40'from the surface opposite to the nozzle plate 130, the diaphragm 41, the plurality of through holes 41a, and the plurality of pressure chambers as shown in FIG. 8 (b). A plurality of through holes 43'that serve as 43 are formed. As a result, the pressure chamber forming plate 40 is manufactured.

Further, as shown in FIG. 9A, after joining the throttle flow path forming plate 60 to the pressure chamber forming plate 40 in the same manner as in the first embodiment, as shown in FIG. 9B, the first The manifold flow path forming plate 70 is joined to the drawing flow path forming plate 60 in the same manner as in the embodiment.

According to the second embodiment of the present invention described above, the direction in which the driver 32 formed on the nozzle plate 130 and the plurality of piezoelectric elements 50 formed on the pressure chamber forming plate 40 are orthogonal to the ink ejection surface 130a. The nozzle plate 130 and the pressure chamber forming plate 40 are joined so as to overlap with each other. As a result, the size of the head unit 125 in the scanning direction can be reduced as compared with the case where the plurality of piezoelectric elements 50 are arranged so as not to overlap the driver 32 in the direction orthogonal to the ink ejection surface 130a. ..

Further, the driver 32 is formed on the surface 130b of the nozzle plate 130 opposite to the ink ejection surface 130a, and is connected to a plurality of terminals of various wirings 54 and 55 via a plurality of conductive bumps 80. Has been done. Therefore, unlike the first embodiment, the plurality of through electrodes 34 are unnecessary. Further, the thickness of each bump 80 is thicker than the thickness of each piezoelectric element 50 in the direction orthogonal to the ink ejection surface 130a. Therefore, in order to prevent the driving of the plurality of piezoelectric elements 50 from being hindered, it is not necessary to form the recess 33 in the nozzle plate 130 as in the first embodiment.

In the second embodiment, SOI (Silicon On Insulator) may be used as the silicon substrate 130'which serves as the nozzle plate 130. By using SOI, the nozzle plate 130 can be accurately set to a desired thickness. In this case, the ink ejection surface 130a is formed of silicon dioxide (SiO ₂ ) contained in SOI.

Although the embodiments and modifications of the present invention have been described above, the present invention is not limited to these, and various design changes can be made as long as they are described in the claims.

In the head units 25 and 125 according to the above embodiments and modifications, one row each of the nozzle row 31a, the row of the pressure chamber 43, and the row of the piezoelectric element 50 is formed, but the present invention is not limited to this. For example, a plurality of nozzle rows may be arranged in the scanning direction, or a plurality of pressure chamber rows may be arranged in the scanning direction corresponding to each of the plurality of nozzle rows. Further, a plurality of piezoelectric element rows may be arranged in the scanning direction corresponding to the plurality of pressure chamber rows.

In the above-described embodiments and modifications, the case where the present invention is applied to the so-called serial head type inkjet printer 1 has been described, but the present invention is not limited thereto. The present invention can also be applied to a so-called line head type inkjet printer in which ink is ejected from a head bar fixed to the inkjet printer and long in the width direction of the recording paper.

In the above-described embodiments and modifications, an example in which the present invention is applied to an inkjet head that ejects ink from a nozzle 31 has been described, but the present invention is not limited thereto. It is also possible to apply the present invention to a liquid ejection head other than an inkjet head that ejects a liquid other than ink from a nozzle.

1 Inkjet printer 4 Inkjet head 25, 125 Head unit 30, 130 Nozzle plate 31 Nozzle 32 Driver 33 Recess 34 Penetration electrode 35 Electrode pad 40 Pressure chamber forming plate 50 Piezoelectric element 60 Squeezing flow path forming plate 70 Manifold flow path forming plate 80 Bump 90 Protective film

Claims (10)

A nozzle substrate having a nozzle surface through which the nozzle opens and a driver is formed,
A flow path substrate having a first surface facing the nozzle substrate and having a flow path communicating with the nozzle.
A piezoelectric element formed on the first surface of the flow path substrate is provided.
The nozzle substrate is a liquid discharge head in which the driver and the piezoelectric element are joined to the first surface of the flow path substrate so as to overlap in the first direction orthogonal to the nozzle surface. The liquid discharge head according to claim 1, wherein the driver is formed on the nozzle surface of the nozzle substrate. The liquid discharge head according to claim 2, wherein the driver is connected to the piezoelectric element via a through electrode that penetrates the nozzle substrate in the first direction. A recess is formed at a position of the nozzle substrate on the surface opposite to the nozzle surface so as to overlap the piezoelectric element in the first direction.
The liquid discharge head according to claim 3, wherein the through electrode is formed in a portion of the nozzle substrate in which the recess is not formed. The liquid discharge head according to any one of claims 1 to 4, wherein a protective film is formed on the inner wall forming the nozzle. A plurality of nozzles including the nozzles are formed on the nozzle substrate.
A plurality of flow paths including the flow path and communicating with the plurality of nozzles are formed in the flow path substrate.
A plurality of piezoelectric elements including the piezoelectric element and corresponding to the plurality of flow paths are provided on the first surface of the flow path substrate.
The plurality of piezoelectric elements form a piezoelectric actuator, and the plurality of piezoelectric elements form a piezoelectric actuator.
The liquid discharge head according to claim 1 or 2, wherein the area of the piezoelectric actuator is equal to or less than the area of the driver. The liquid discharge head according to claim 1, wherein the driver is formed on a surface of the nozzle substrate opposite to the nozzle surface. The driver is connected to the piezoelectric element via bumps, and the driver is connected to the piezoelectric element.
The liquid discharge head according to claim 7, wherein the thickness of the bump in the first direction is larger than the thickness of the piezoelectric element in the first direction. The liquid discharge head according to claim 8, wherein the nozzle substrate is formed of SOI. The liquid discharge head according to claim 9, wherein the nozzle surface of the nozzle substrate is formed of SiO ₂ .

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