JP2021024151A - Liquid ejection head, and liquid ejection device - Google Patents

Abstract

To provide a liquid ejection head and a liquid ejection device, in which deviation of ejection characteristics is reduced.SOLUTION: A liquid ejection head has: a piezoelectric substance; a first electrode positioned at an upper portion of the piezoelectric substance; a second electrode positioned at a lower portion of the piezoelectric substance; wiring which applies voltage to the first electrode or the second electrode; and a protection portion which forms a space at the upper portion of the piezoelectric substance. When a position where distance between the piezoelectric substance and the protection portion is first distance, is represented by a first position and a position where distance between the piezoelectric substance and the protection portion is second distance shorter than the first distance, is represented by a second position, thickness of the wiring at the first position is larger than thickness of the wiring at the second position.SELECTED DRAWING: Figure 7

Description

The present invention relates to a liquid discharge head and a liquid discharge device.

Conventionally, a liquid discharge head that discharges a liquid in a pressure chamber from a nozzle by a piezoelectric element has been proposed. The piezoelectric element described in Patent Document 1 includes a piezoelectric body, individual electrodes provided on one surface of the piezoelectric body, and a common electrode provided on the other surface of the piezoelectric body.

JP-A-2009-172878

Generally, a voltage is applied to each of the individual electrodes and the common electrode via wiring. For example, if the length of the wiring is long, a voltage drop may occur and a desired voltage may not be applied to the piezoelectric element. For example, if the wiring resistance is lowered by increasing the thickness of the entire wiring, the voltage drop can be reduced. However, if the thickness of the entire wiring is increased, a space for arranging the thickened wiring is required, and as a result, the liquid discharge head becomes large.

In order to solve the above problems, the liquid discharge head according to a preferred embodiment of the present invention is a liquid discharge head that discharges a liquid, and includes a piezoelectric body, a first electrode located above the piezoelectric body, and a first electrode. The piezoelectric body has a second electrode located below the piezoelectric body, a wiring for applying a voltage to the first electrode or the second electrode, and a protective portion for forming a space above the piezoelectric body. The first position is the position where the distance between the body and the protective portion is the first distance, and the second position is the position where the distance between the piezoelectric body and the protective portion is the second distance shorter than the first distance. Then, the thickness of the wiring at the first position is larger than the thickness of the wiring at the second position.

It is a block diagram which illustrates the structure of the liquid discharge device which concerns on embodiment. It is an exploded perspective view of the liquid discharge head. It is sectional drawing of the liquid discharge head. It is a top view which shows a part of a diaphragm and a piezoelectric element. It is sectional drawing of the piezoelectric element. It is a top view of the piezoelectric element. It is an enlarged sectional view of a piezoelectric element and a part of the vicinity thereof.

1. 1. Embodiment 1-1. Overall configuration of the liquid discharge device 100 FIG. 1 is a configuration diagram illustrating the liquid discharge device 100 according to the embodiment. In the following, for convenience of explanation, the X-axis, the Y-axis, and the Z-axis will be described as appropriate. The X-axis, Y-axis, and Z-axis are orthogonal to each other. In addition, the direction indicated by the arrow on the X axis is the + X direction, and the opposite direction is the −X direction. The same applies to the Y-axis and the Z-axis. The XY plane including the X-axis and the Y-axis corresponds to a horizontal plane. The Z-axis is an axis along the vertical direction, and the + Z direction corresponds to the lower part in the vertical direction. The + Z direction is "up" and the -Z direction is "down". In the present specification, the "first direction" is the + Y direction. The "second direction" is the + X direction. Further, in the present specification, the expression "element B is arranged above element A" is not limited to a configuration in which element A and element B are in direct contact with each other. A configuration in which the element A and the element B are not in direct contact with each other is also included in the concept that "the element B is arranged on the element A". Similarly, the expression "element B is arranged below element A" is not limited to a configuration in which element A and element B are in direct contact with each other.

The liquid ejection device 100 is an inkjet printing apparatus that ejects ink, which is an example of "liquid", to the medium 12. The medium 12 is typically printing paper, but a printing target of any material such as a resin film or cloth is used as the medium 12. As illustrated in FIG. 1, a liquid container 14 for storing ink is installed in the liquid ejection device 100. For example, a cartridge that can be attached to and detached from the liquid ejection device 100, a bag-shaped ink pack made of a flexible film, or an ink tank that can be refilled with ink is used as the liquid container 14.

As illustrated in FIG. 1, the liquid discharge device 100 includes a control unit 20, a transfer mechanism 22, a moving mechanism 24, and a liquid discharge head 26. The control unit 20 is an example of a “control unit”. The control unit 20 includes one or a plurality of processing circuits such as a CPU (Central Processing Unit) or an FPGA (Field Programmable Gate Array) and one or a plurality of storage circuits such as a semiconductor memory, and each element of the liquid discharge device 100. Is controlled comprehensively. For example, the control unit 20 controls the operation of the liquid discharge head 26.

The transport mechanism 22 transports the medium 12 in the + Y direction under the control of the control unit 20. The moving mechanism 24 reciprocates the liquid discharge head 26 along the X axis under the control of the control unit 20. The X-axis intersects the Y-axis along the direction in which the medium 12 is conveyed. The moving mechanism 24 includes a substantially box-shaped transport body 242 that accommodates the liquid discharge head 26, and a transport belt 244 to which the transport body 242 is fixed. It should be noted that a configuration in which a plurality of liquid discharge heads 26 are mounted on the transport body 242 or a configuration in which the liquid container 14 is mounted on the transport body 242 together with the liquid discharge head 26 may be adopted.

The liquid ejection head 26 ejects the ink supplied from the liquid container 14 from a plurality of nozzles to the medium 12 under the control of the control unit 20. An image is formed on the surface of the medium 12 by each liquid ejection head 26 ejecting ink to the medium 12 in parallel with the conveying of the medium 12 by the conveying mechanism 22 and the repetitive reciprocation of the conveying body 242.

1-2. Overall Configuration of Liquid Discharge Head 26 FIG. 2 is an exploded perspective view of the liquid discharge head 26. FIG. 3 is a cross-sectional view taken along the line aa in FIG. The cross section shown in FIG. 3 is a cross section parallel to the XZ plane. The Z-axis is an axis along the ink ejection direction of the liquid ejection head 26.

As illustrated in FIG. 2, the liquid discharge head 26 includes a plurality of nozzles N arranged along the Y axis. The plurality of nozzles N are divided into a first nozzle row La and a second nozzle row Lb arranged side by side at intervals along the X axis. Each of the first nozzle row La and the second nozzle row Lb is a set of a plurality of nozzles N linearly arranged along the Y axis. The liquid discharge head 26 has a structure in which elements related to each nozzle N of the first nozzle row La and elements related to each nozzle N of the second nozzle row Lb are arranged substantially symmetrically. Therefore, in the following description, the elements corresponding to the first nozzle row La will be mainly described, and the description of the elements corresponding to the second nozzle row Lb will be omitted as appropriate.

As illustrated in FIGS. 2 and 3, the liquid discharge head 26 includes a flow path structure 30, a plurality of piezoelectric elements 34, a protective portion 35, a housing portion 36, and a wiring board 51. The flow path structure 30 is a structure in which a flow path for supplying ink to each of the plurality of nozzles N is formed inside. The flow path structure 30 is composed of a flow path substrate 31, a pressure chamber substrate 32, a diaphragm 33, a nozzle plate 41, and a vibration absorbing body 42. Each member constituting the flow path structure 30 is a long plate-shaped member along the Y axis. The pressure chamber substrate 32 and the housing portion 36 are installed on the surface of the flow path substrate 31 on the + Z axis side. On the other hand, the nozzle plate 41 and the vibration absorbing body 42 are installed on the surface of the flow path substrate 31 on the −Z axis side. For example, each member is fixed by an adhesive.

The nozzle plate 41 is a plate-shaped member in which a plurality of nozzles N are formed. Each of the plurality of nozzles N is a circular through hole for ejecting ink. For example, the nozzle plate 41 is manufactured by processing a silicon (Si) single crystal substrate using semiconductor manufacturing techniques such as photolithography and etching. However, a known material or manufacturing method can be arbitrarily adopted for manufacturing the nozzle plate 41.

As illustrated in FIGS. 2 and 3, the flow path substrate 31 is formed with a space Ra, a plurality of supply flow paths 312, a plurality of communication flow paths 314, and a relay liquid chamber 316. The space Ra is an opening formed in a long shape along the Y axis. Each of the supply flow path 312 and the communication flow path 314 is a through hole formed for each nozzle N. The relay liquid chamber 316 is a space formed in a long shape along the Y axis over a plurality of nozzles N, and allows the space Ra and the plurality of supply flow paths 312 to communicate with each other. Each of the plurality of communication flow paths 314 overlaps one nozzle N corresponding to the communication flow path 314 in a plan view from the + Z direction.

As illustrated in FIGS. 2 and 3, a plurality of pressure chambers C1 are formed on the pressure chamber substrate 32. The pressure chamber C1 is located between the nozzle plate 41 and the diaphragm 33, and is formed by the wall surface 320 of the pressure chamber substrate 32. The pressure chamber C1 is a long space along the X axis in a plan view seen from the + Z direction. The pressure chamber C1 is formed for each nozzle N. The plurality of pressure chambers C1 are arranged along the Y axis. The flow path substrate 31 and the pressure chamber substrate 32 are manufactured by processing a silicon single crystal substrate by using, for example, a semiconductor manufacturing technique, similarly to the nozzle plate 41 described above. However, known materials and manufacturing methods can be arbitrarily adopted for manufacturing the flow path substrate 31 and the pressure chamber substrate 32.

As illustrated in FIG. 3, an elastically deformable diaphragm 33 is arranged above the pressure chamber C1. The diaphragm 33 comes into contact with the surface of the pressure chamber substrate 32 opposite to the flow path substrate 31. The diaphragm 33 is a plate-shaped member formed in a long rectangular shape along the Y-axis in a plan view from the + Z direction. As illustrated in FIGS. 2 and 3, the pressure chamber C1 communicates with the communication flow path 314 and the supply flow path 312. Therefore, the pressure chamber C1 communicates with the nozzle N via the communication flow path 314 and communicates with the space Ra via the supply flow path 312 and the relay liquid chamber 316. Although the pressure chamber substrate 32 and the diaphragm 33 are shown as separate substrates in FIG. 2 for ease of explanation, they are actually laminated on one silicon substrate. A part or all of the diaphragm 33 may be a separate member from the pressure chamber substrate 32, or may be integrated with the pressure chamber substrate 32.

As illustrated in FIG. 3, a piezoelectric element 34 is formed in each pressure chamber C1 on the surface of the diaphragm 33 opposite to the pressure chamber C1. The piezoelectric element 34 is a long passive element along the X axis in a plan view seen from the + Z direction. As illustrated in FIG. 2, the plurality of piezoelectric elements 34 are divided into a first piezoelectric element row L1 and a second piezoelectric element row L2 arranged side by side at intervals along the X axis. Each of the first piezoelectric element row L1 and the second piezoelectric element row L2 is a set of a plurality of piezoelectric elements 34 arranged linearly. The direction in which the plurality of piezoelectric elements 34 included in the first piezoelectric element row L1 are arranged is a direction along the + Y direction. Similarly, the direction in which the plurality of piezoelectric elements 34 included in the second piezoelectric element row L2 are lined up is the direction along the + Y direction. The direction in which the first piezoelectric element row L1 and the second piezoelectric element row L2 are lined up is the direction along the + X direction.

The housing portion 36 illustrated in FIG. 3 is a case for storing ink supplied to a plurality of pressure chambers C1, and is formed, for example, by injection molding of a resin material. A space Rb and a supply port 361 are formed in the housing portion 36. The supply port 361 is a pipeline in which ink is supplied from the liquid container 14, and communicates with the space Rb. The space Rb of the housing portion 36 and the space Ra of the flow path substrate 31 communicate with each other. The space composed of the space Ra and the space Rb functions as a liquid storage chamber R for storing ink supplied to the plurality of pressure chambers C1. The ink supplied from the liquid container 14 and passing through the supply port 361 is stored in the liquid storage chamber R. The ink stored in the liquid storage chamber R branches from the relay liquid chamber 316 to each supply flow path 312, and is supplied and filled in parallel to the plurality of pressure chambers C1. Further, as illustrated in FIGS. 2 and 3, a through hole 362 through which the wiring board 51 is inserted is formed in the center of the housing portion 36. Further, the vibration absorbing body 42 is a flexible film constituting the wall surface of the liquid storage chamber R, and absorbs the pressure fluctuation of the ink in the liquid storage chamber R.

The protection unit 35 is a structure that protects the plurality of piezoelectric elements 34 and reinforces the mechanical strength of the pressure chamber substrate 32 and the diaphragm 33. The protective portion 35 is fixed to the surface of the diaphragm 33 or the like with, for example, an adhesive 70. A recess 350 is formed in the protective portion 35. The recess 350 is a recess formed on the surface of the protective portion 35 facing the diaphragm 33. The recess 350 is commonly formed in the plurality of piezoelectric elements 34, and forms a space above the plurality of piezoelectric elements 34. The recess 350 allows displacement of the piezoelectric element 34 due to vibration. The protection unit 35 is manufactured by processing a silicon single crystal substrate using, for example, semiconductor manufacturing technology. Further, a through hole 301 through which the wiring board 51 is inserted is formed in the center of the protection portion 35.

As illustrated in FIG. 3, the wiring board 51 is inserted through the through hole 362 of the housing portion 36 and the through hole 301 of the protective portion 35, and is joined to the surface of the diaphragm 33. The wiring board 51 is a mounting component on which a plurality of wirings for electrically connecting the control unit 20 and the liquid discharge head 26 are formed. For example, a flexible wiring board 51 such as an FPC (Flexible Printed Circuit) or an FFC (Flexible Flat Cable) is preferably adopted. A drive signal and a reference voltage for driving the piezoelectric element 34 are supplied from the wiring board 51 to each piezoelectric element 34.

1-3. Detailed configuration of a part of the liquid discharge head 26 The diaphragm 33, the piezoelectric element 34, and the wiring 300 electrically connected to the piezoelectric element 34 will be described in detail. FIG. 4 is a plan view showing a part of the diaphragm 33 and the piezoelectric element 34. In FIG. 4, the illustration of the piezoelectric body 343 described later is omitted for convenience. FIG. 5 is a cross-sectional view of the piezoelectric element 34, and corresponds to a cross-sectional view of line bb in FIG. FIG. 6 is a plan view of the piezoelectric element 34. In FIG. 6, for convenience, the illustration of the first electrode 341 and the wiring 300, which will be described later, is omitted. Further, in FIG. 6, dots are added to the piezoelectric body 343, which will be described later, for convenience.

1-3a. Diaphragm 33
The diaphragm 33 illustrated in FIGS. 4 to 6 vibrates by driving the piezoelectric element 34. As illustrated in FIG. 5, the diaphragm 33 is composed of a laminate of the first insulating layer 331 and the second insulating layer 332. The first insulating layer 331 comes into contact with the pressure chamber substrate 32. The second insulating layer 332 is located opposite to the pressure chamber substrate 32 with respect to the first insulating layer 331. The first insulating layer 331 is an elastic film formed of an elastic material such as _{silicon dioxide (SiO 2).} The second insulating layer 332 is formed of an insulating material such as _{zirconium dioxide (ZrO 2).} Each of the first insulating layer 331 and the second insulating layer 332 is formed by a known film forming technique such as thermal oxidation or sputtering. By selectively removing a part of the plate-shaped member having a predetermined plate thickness in the plate thickness direction in the region corresponding to the pressure chamber C1, the pressure chamber substrate 32 and a part or all of the diaphragm 33 can be removed. It can be formed integrally.

1-3b. Piezoelectric element 34
As illustrated in FIG. 5, the piezoelectric element 34 is roughly a structure in which the second electrode 342, the piezoelectric body 343, and the first electrode 341 are laminated in the above order from the diaphragm 33 side. The first electrode 341 is located above the piezoelectric body 343. The second electrode 342 is located below the piezoelectric body 343. In this specification, the expression "element B is formed on the surface of element A" is not limited to the configuration in which element A and element B are in direct contact with each other. That is, even in a configuration in which the element C is formed on the surface of the element A and the element B is formed on the surface of the element C, a part or all of the element A and the element B overlap in a plan view seen from the + Z direction. If so, it is included in the concept that "element B is formed on the surface of element A".

As illustrated in FIG. 5, the second electrode 342 is formed on the surface of the diaphragm 33. The second electrode 342 is an individual electrode formed so as to be separated from each other for each piezoelectric element 34. A drive signal whose voltage fluctuates is applied to the second electrode 342. As illustrated in FIG. 4, the second electrode 342 has a long shape along the X axis. The second electrodes 342 of the first piezoelectric element row L1 are arranged along the Y axis at intervals from each other. Similarly, the second electrodes 342 of the second piezoelectric element row L2 are arranged along the Y axis at intervals from each other. The second electrode 342 is formed of a conductive material such as platinum (Pt) or iridium (Ir).

As illustrated in FIG. 5, the piezoelectric body 343 is formed on the upper portion of the second electrode 342 and comes into contact with the second electrode 342. The piezoelectric body 343 exemplified in FIG. 6 is a strip-shaped dielectric film continuous along the Y axis across a plurality of piezoelectric elements 34. The piezoelectric body 343 is formed of a known piezoelectric material such as lead zirconate titanate (Pb (Zr, Ti) O _3). A notch G along the X axis is formed in the region of the piezoelectric body 343 corresponding to the gap between the pressure chambers C1 adjacent to each other. The notch G is an opening that penetrates the piezoelectric body 343. By forming the notch G, each piezoelectric element 34 is individually deformed for each pressure chamber C1, and the propagation of vibration between the piezoelectric elements 34 is suppressed. A bottomed hole obtained by removing a part of the piezoelectric body 343 in the thickness direction may be formed as a notch G.

As illustrated in FIG. 5, the piezoelectric body 343 has a plurality of piezoelectric body portions 340 individually separated for each pressure chamber C1 by a notch G. The piezoelectric body portion 340 is provided for each pressure chamber C1 and overlaps with the pressure chamber C1 in a plan view in the XY plane. Of the plurality of piezoelectric parts 340, any piezoelectric part 340 is the first piezoelectric body 340a. Of the plurality of piezoelectric parts 340, another arbitrary piezoelectric part 340 that is aligned with the first piezoelectric body 340a along the Y axis and is provided at a position different from that of the first piezoelectric body 340a is the second piezoelectric body 340b.

As illustrated in FIG. 5, the first electrode 341 comes into contact with the piezoelectric body 343. The first electrode 341 is a common electrode commonly provided for the first piezoelectric body 340a and the second piezoelectric body 340b. The above-mentioned second electrode 342 is individually provided for the first piezoelectric body 340a and the second piezoelectric body 340b. As illustrated in FIG. 4, the first electrode 341 is a band-shaped electrode extending along the Y axis so as to be continuous over the plurality of piezoelectric elements 34. Further, the first electrode 341 is provided in each of the first piezoelectric element row L1 and the second piezoelectric element row L2. The first electrode 341 provided in the first piezoelectric element row L1 and the first electrode 341 provided in the second piezoelectric element row L2 may be connected.

A predetermined reference voltage is applied to the first electrode 341. The reference voltage is a constant voltage, for example set to a voltage higher than the ground voltage. That is, for example, a holding signal having a constant voltage is applied to the first electrode 341. A voltage corresponding to the difference between the reference voltage applied to the first electrode 341 and the drive signal supplied to the second electrode 342 is applied to the piezoelectric body 343. The drive signal differs depending on the discharge amount. The holding signal is constant regardless of the discharge amount and does not fluctuate. A ground voltage may be applied to the first electrode 341. Further, the first electrode 341 is formed of a low resistance conductive material such as platinum (Pt) or iridium (Ir).

When a voltage is applied between the second electrode 342 and the first electrode 341, the piezoelectric body 343 is deformed, so that the piezoelectric element 34 generates energy for bending and deforming the diaphragm 33. The pressure in the pressure chamber C1 changes as the diaphragm 33 vibrates due to the energy generated by the piezoelectric element 34, and the ink in the pressure chamber C1 is ejected from the nozzle N shown in FIG.

1-3c. Wiring 300
FIG. 7 is an enlarged cross-sectional view of the piezoelectric element 34 and a part in the vicinity thereof, and corresponds to a cross-sectional view of line cc in FIG. As illustrated in FIG. 7, a part of the communication flow path 314 communicating with the plurality of pressure chambers C1 is formed on the pressure chamber substrate 32. The communication flow path 314 is formed by the pressure chamber substrate 32 and the above-mentioned flow path substrate 31. Further, a metal layer 344 that fills the space between the second insulating layer 332 and the piezoelectric body 343 and is insulated from the second electrode 342 is arranged.

As illustrated in FIG. 4, the wiring 300 includes a plurality of second wirings 39 for applying a voltage to the second electrode 342 and a plurality of first wirings 38 for applying a voltage to the first electrode 341. As illustrated in FIG. 4, the plan-view shape of the second wiring 39 is a longitudinal shape extending along the X-axis. As illustrated in FIG. 7, the second wiring 39 has a portion that contacts the upper surface of the second electrode 342 and a portion that contacts the upper surface 349 of the piezoelectric body 343. Further, the second wiring 39 comes into contact with the end 3430 on the −X axis side of the piezoelectric body 343. The second wiring 39 applies a drive signal to the second electrode 342. The second wiring 39 is a lead wiring to which a drive signal is supplied from a drive circuit (not shown) mounted on the wiring board 51 shown in FIG.

As illustrated in FIG. 4, in this embodiment, the number of the first wiring 38 is two. Each first wiring 38 forms a frame shape extending along the Y axis. One of the two first wirings 38 is provided corresponding to the first electrode 341 of the first piezoelectric element train L1. The other of the two first wirings 38 is provided corresponding to the first electrode 341 of the second piezoelectric element train L2. However, the number of the first wiring 38 may be one. In that case, the two first wirings 38 shown in FIG. 4 may be connected to each other.

As illustrated in FIG. 7, the first wiring 38 is located above the first electrode 341 and comes into contact with the first electrode 341. In the illustrated example, the first wiring 38 has a portion in contact with the piezoelectric body 343, but may not have the portion. Further, the first wiring 38 applies a reference voltage to the first electrode 341. A reference voltage (not shown) is supplied to the first wiring 38 via the wiring board 51 shown in FIG. Further, by providing the first wiring 38, the voltage drop of the reference voltage at the first electrode 341 is suppressed. The first wiring 38 also functions as a weight for suppressing the vibration of the diaphragm 33.

As illustrated in FIGS. 4 and 7, the first wiring 38 has a strip-shaped first wiring portion 381 extending in the + Y direction and a strip-shaped second wiring portion 382 extending in the + Y direction. The first wiring portion 381 and the second wiring portion 382 are arranged along the X axis. That is, the first wiring portion 381 and the second wiring portion 382 are provided at different positions in the + X direction intersecting the + Y direction.

As illustrated in FIG. 7, the first wiring 38 has a first layer 383 and a second layer 384. The first layer 383 comes into contact with the first electrode 341. In the illustrated example, the thickness D15 of the first layer 383 is equal to the thickness D20 of the second wiring 39 and smaller than the thickness D16 of the second layer 384. The thickness is the length along the Z axis. The flat area of the first layer 383 in the XY plane is larger than the flat area of the second layer 384 in the XY plane. Further, the second layer 384 is arranged in the recess 350 of the protective portion 35. The second layer 384 is in contact with a part of the first layer 383. In other words, the second layer 384 is not laminated on a part of the upper surface of the first layer 383. The portion of the first layer 383 on which the second layer 384 is not laminated is joined to the protective portion 35 by the adhesive 70. The portion of the first layer 383 on which the second layer 384 is laminated overlaps the recess 350 in a plan view in the XY plane.

The thickness D10 of the portion of the first wiring 38 that overlaps the recess 350 in the plan view from the + Z direction is the thickness D15 of the portion of the first wiring 38 that does not overlap the recess 350 in the plan view from the + Z direction, that is, the first wiring 38. It is larger than the thickness D15 of one layer 383. The thickness D10 is the distance from the upper surface of the first electrode 341 to the upper surface of the second layer 384. The thickness D15 is the distance from the upper surface of the first electrode 341 to the upper surface of the first layer 383. The thickness D10 may be regarded as the distance from the upper surface 349 of the piezoelectric body 343 to the upper surface of the second layer 384. Similarly, the thickness D15 may be regarded as the distance from the upper surface 349 of the piezoelectric body 343 to the upper surface of the first layer 383.

As illustrated in FIG. 7, the protective portion 35 is separated from the piezoelectric body 343. The first distance D1 between the bottom surface 358 of the recess 350 of the protective portion 35 and the upper surface 349 of the piezoelectric body 343 is longer than the second distance D2 between the lower surface 359 of the protective portion 35 and the upper surface 349 of the piezoelectric body 343. .. In the illustrated example, the first distance D1 is substantially constant, and the second distance D2 is substantially constant. Further, the first wiring 38 is separated from the protective portion 35 in the recess 350.

In the + X direction, the thickness D10 of the first wiring 38 at the position P1 which is the first distance D1 is larger than the thickness D15 of the first wiring 38 at the position P2A which is the second distance D2. The position P1 is an example of the "first position", and the position P2A is an example of the "second position". The first wiring 38 is provided at both the position P1 and the position P2A. Therefore, the first wiring 38 has a portion having a different thickness. The position P1 is a position in the recess 350 in the + X direction. On the other hand, the position P2A is near the end 3410 of the first electrode 341. Therefore, the position P2A is closer to the end 3410 than the position P1. The end 3410 is an end of the first electrode 341 close to the second wiring 39 in the + X direction.

By making the thickness D10 of the first wiring 38 at the position P1 thicker than the thickness D15 of the first wiring 38 at the position P2A, the wiring resistance is reduced without uniformly increasing the thickness of the entire first wiring 38. Can be made to. Therefore, the voltage drop in the first wiring 38 and the first electrode 341 can be suppressed. Therefore, it is possible to reduce the deviation of the discharge characteristic due to the voltage drop while avoiding the increase in size of the liquid discharge head 26. By setting the thickness of the first wiring 38 according to the shape of the protective portion 35, the effect of reducing the deviation of the discharge characteristic based on the voltage drop is suitably exhibited while avoiding the increase in size of the liquid discharge head 26. be able to. Further, a part of the first wiring 38, specifically, the end 3410 of the first electrode 341 and its vicinity are joined to the protective portion 35 by the adhesive 70. Therefore, the piezoelectric element 34 can be suitably protected during the manufacture of the liquid discharge head 26, and thus damage to the piezoelectric element 34 can be suppressed.

The first wiring 38 at the position P1 is composed of a laminated body of the first layer 383 and the second layer 384. On the other hand, the first wiring 38 at the position P2A is composed of a portion where the second layer 384 is not laminated. That is, the first wiring 38 at the position P2A is composed of the first layer 383 without the second layer 384 laminated. In other words, the first wiring 38 at position P2A does not have a second layer 384. By selectively forming the second layer 384 at the position P1, the thickness D10 at the position P1 of the first wiring 38 can be easily and appropriately made larger than the thickness D15 at the position P2A of the first wiring 38. it can. Therefore, as compared with the case where the first wiring 38 at the position P1 is a single layer, the first wiring 38 having two portions having different thicknesses at the position P1 and the position P2A can be easily manufactured as designed. it can. The first wiring 38 at position P1 may be composed of a laminated body including other layers in addition to the first layer 383 and the second layer 384.

The thickness D16 of the second layer 384 is larger than the thickness D15 of the first layer 383. Therefore, the wiring resistance of the first wiring 38 can be reduced as compared with the case where the thickness D16 is smaller than the thickness D15. The thickness D16 may be smaller or equal to the thickness D15.

Further, in the + X direction, the thickness D10 of the first wiring 38 at the position P1 is larger than the thickness D20 of the second wiring 39 at the position P2B which is the second distance D2. Position P2B is an example of a "second position". The first wire 38 is provided at position P1 and the second wire 39 is provided at position P2B. In FIG. 7, the position of the end 3430 on the −X axis side of the piezoelectric body 343 in the + X direction coincides with the position P2B. The end 3430 is an end of the piezoelectric body 343 in contact with the second wiring 39 in the + X direction. As described above, the length of the first wiring 38 along the Y axis is longer than the length of the second wiring 39 along the X axis. Therefore, the voltage drop of the first wiring 38 is more likely to occur due to the voltage resistance than that of the second wiring 39. Therefore, by making the thickness of the first wiring 38 larger than the thickness of the second wiring 39, the deviation of the discharge characteristic due to the voltage drop can be reduced particularly effectively. That is, by providing the first wiring 38 at the position P1, the deviation of the discharge characteristic based on the voltage drop can be reduced particularly effectively.

As described above, the first wiring 38 applies a holding signal having a constant voltage to the first electrode 341. The first electrode 341 is a common electrode commonly provided for the first piezoelectric body 340a and the second piezoelectric body 340b shown in FIG. On the other hand, the second wiring 39 applies a drive signal whose voltage fluctuates to the second electrode 342. The second electrode 342 is an individual electrode provided individually for the first piezoelectric body 340a and the second piezoelectric body 340b shown in FIG. Since the first electrode 341 is a common electrode in the plurality of piezoelectric elements 34, the voltage deviation in the first electrode 341 affects the voltage deviation in the plurality of piezoelectric elements 34. Therefore, by providing the first wiring 38 at the position P1, the deviation of the discharge characteristic based on the voltage drop can be reduced particularly effectively.

As illustrated in FIG. 7, the first wiring 38 includes a first wiring portion 381 and a second wiring portion 382. Since the first wiring 38 includes the first wiring portion 381 and the second wiring portion 382, as compared with the case where the first wiring 38 is composed of only one of the first wiring portion 381 and the second wiring portion 382. The deviation of the discharge characteristic based on the voltage drop can be reduced.

As illustrated in FIG. 4, the first wiring 38 is not provided at least in a part between the first wiring portion 381 and the second wiring portion 382. Specifically, the first wiring 38 has a frame shape having a through hole C3. Since the first wiring 38 is separated into the first wiring portion 381 and the second wiring portion 382, the through hole C3 can be provided. Therefore, the first wiring 38 can be arranged so as to avoid the center of each pressure chamber C1. Therefore, the flat area of the first wiring 38 can be increased without hindering the deformation of the diaphragm 33. Therefore, the voltage drop can be reduced while ensuring the required amount of deformation of the diaphragm 33.

The second wiring 39 illustrated in FIG. 7 is made of a conductive material having a lower resistance than the second electrode 342. Similarly, the first wiring 38 is made of a conductive material having a lower resistance than the first electrode 341. The first layer 383 preferably contains a conductive material having excellent adhesion to the first electrode 341 and having low resistance. Specifically, for example, the second wiring 39 and the first layer 383 are each a conductive pattern having a structure in which a gold (Au) conductive film is laminated on the surface of a conductive film formed of nichrome (NiCr). On the other hand, the second layer 384 preferably contains the same metal as the first layer 383. For example, when the first layer 383 contains gold (Au), the second layer 384 is preferably a conductive film such as gold (Au).

Since the first layer 383 and the second layer 384 contain gold (Au), it is easy to realize the first wiring 38 having a lower resistance than the second electrode 342. Further, since the first layer 383 and the second layer 384 contain gold (Au), the selectivity of the constituent material of the second electrode 342 can be enhanced. Further, since the first layer 383 and the second layer 384 contain the same metal, it is easy to improve the adhesion between the first layer 383 and the second layer 384 as compared with the case where the first layer 383 and the second layer 384 contain the same metal. Further, since the first layer 383 and the second layer 384 are made of the same metal, it is possible to prevent the process load of the manufacturing process of the first wiring 38 from being significantly increased.

The first layer 383 and the second layer 384 may be made of different materials, or all the materials constituting the first layer 383 and all the materials constituting the second layer 384 may be the same. Further, the first layer 383 may contain a metal other than nichrome and gold. The second layer 384 may contain a metal other than gold. Further, the second wiring 39 and the first wiring 38 may contain a material other than metal. Further, the first layer 383 and the second wiring 39 may be made of different materials, or may be formed in different steps. The first layer 383 and the second layer 384 may be formed of a plurality of layers or a single layer, respectively. The second wiring 39 may be formed of a plurality of layers or may be formed of a single layer.

The method of manufacturing the first wiring 38 and the second wiring 39 is arbitrary. Specifically, for example, the second layer 384 is selectively formed on the upper surface of the first layer 383 by photolithography. Further, the second layer 384 may be formed, for example, by forming a metal layer on the first layer 383 and then removing a part of the metal layer by photolithography. Further, the second layer 384 may be formed by a coating method such as coating using a dispenser, transfer coating, and coating using an inkjet.

The liquid discharge head 26 that operates under the control of the control unit 20 described above can particularly effectively reduce the deviation of the discharge characteristics. Therefore, according to the liquid discharge device 100, highly accurate liquid discharge can be realized.

2. 2. Modifications The embodiments illustrated above can be variously modified. Specific embodiments that can be applied to the above-described embodiments are illustrated below. Two or more embodiments arbitrarily selected from the following examples can be appropriately merged to the extent that they do not contradict each other.

In the above-described embodiment, all of the first electrodes 341 are located above the piezoelectric body 343, but a part of the first electrode 341 does not have to be located above the piezoelectric body 343. Although all of the second electrode 342 is located below the piezoelectric body 343, a part of the second electrode 342 does not have to be located below the piezoelectric body 343.

In the above-described embodiment, the diaphragm 33 includes the first insulating layer 331 and the second insulating layer 332, but the diaphragm 33 may omit, for example, the second insulating layer 332.

In the above-described embodiment, the first electrode 341 of the piezoelectric element 34 is used as a common electrode and the second electrode 342 is used as an individual electrode, but the first electrode 341 may be used as an individual electrode and the second electrode 342 may be used as a common electrode. Further, both the first electrode 341 and the second electrode 342 may be used as individual electrodes.

In the above-described embodiment, the piezoelectric element 34 is a structure in which the second electrode 342, the piezoelectric body 343, and the first electrode 341 are laminated, but the piezoelectric element is located between the second electrode 342 and the piezoelectric body 343. Other elements may intervene to the extent that the function as 34 is not impaired. Similarly, another element may be interposed between the first electrode 341 and the piezoelectric body 343.

In the above-described embodiment, the serial type liquid discharge device 100 that reciprocates the transport body 242 on which the liquid discharge head 26 is mounted is illustrated, but in the line type liquid discharge device in which a plurality of nozzles N are distributed over the entire width of the medium 12. It is also possible to apply the present invention.

The liquid discharge device 100 illustrated in the above-described embodiment can be adopted in various devices such as a facsimile machine and a copier, in addition to a device dedicated to printing. However, the application of the liquid discharge device of the present invention is not limited to printing. For example, a liquid discharge device that discharges a solution of a coloring material is used as a manufacturing device for forming a color filter of a display device such as a liquid crystal display panel. Further, a liquid discharge device that discharges a solution of a conductive material is used as a manufacturing device for forming wirings and electrodes on a wiring board. Further, a liquid discharge device for discharging a solution of an organic substance related to a living body is used as, for example, a manufacturing device for manufacturing a biochip.

12 ... Medium, 14 ... Liquid container, 20 ... Control unit, 22 ... Conveying mechanism, 24 ... Moving mechanism, 26 ... Liquid discharge head, 30 ... Flow path structure, 31 ... Flow path substrate, 32 ... Pressure chamber substrate, 33 ... Vibrating plate, 34 ... Piezoelectric element, 35 ... Protective part, 36 ... Housing part, 38 ... First wiring, 39 ... Second wiring, 41 ... Nozzle plate, 42 ... Vibration absorber, 51 ... Wiring board, 70 ... Adhesion Agent, 100 ... Liquid discharge device, 242 ... Conveyor body, 244 ... Conveyor belt, 300 ... Wiring, 301 ... Through hole, 312 ... Supply flow path, 314 ... Communication flow path, 316 ... Relay liquid chamber, 320 ... Wall surface, 331 ... 1st insulating layer, 332 ... 2nd insulating layer, 340 ... Piezoelectric part, 340a ... 1st piezoelectric body, 340b ... 2nd piezoelectric body, 341 ... 1st electrode, 342 ... 2nd electrode, 343 ... Piezoelectric body, 349 ... Top surface, 350 ... Recessed part, 358 ... Bottom surface, 359 ... Bottom surface, 361 ... Supply port, 362 ... Through hole, 381 ... First wiring part, 382 ... Second wiring part, 383 ... First layer, 384 ... Second Layer, 3410 ... end, 3430 ... end, C1 ... pressure chamber, C3 ... through hole, D1 ... first distance, D2 ... second distance, G ... notch, L1 ... first piezoelectric element row, L2 ... second piezoelectric element Row, La ... 1st nozzle row, Lb ... 2nd nozzle row, N ... nozzle, R ... liquid storage chamber, Ra ... space, Rb ... space, D10 ... thickness, D15 ... thickness, D16 ... thickness, D20 ... thickness, P1 ... position, P2A ... position, P2B ... position.

Claims (13)

A liquid discharge head that discharges liquid
Piezoelectric and
The first electrode located on the upper part of the piezoelectric body and
The second electrode located at the bottom of the piezoelectric body and
Wiring that applies voltage to the first electrode or the second electrode,
It has a protective portion that forms a space above the piezoelectric body, and has.
The position where the distance between the piezoelectric body and the protective portion is the first distance is defined as the first position.
When the position where the distance between the piezoelectric body and the protective portion is the second distance shorter than the first distance is defined as the second position,
The liquid discharge head, characterized in that the thickness of the wiring at the first position is larger than the thickness of the wiring at the second position. The liquid discharge head according to claim 1, wherein the wiring at the first position includes a first layer and a second layer laminated on the upper portion of the first layer. The liquid discharge head according to claim 2, wherein the wiring at the second position does not include the second layer. The liquid discharge head according to claim 2 or 3, wherein the first layer and the second layer contain the same metal. The liquid discharge head according to any one of claims 2 to 4, wherein the thickness of the second layer is larger than the thickness of the first layer. The wiring includes a first wiring for applying a voltage to the first electrode and a second wiring for applying a voltage to the second electrode.
The liquid discharge head according to any one of claims 1 to 5, wherein the first wiring is provided at both the first position and the second position. The liquid discharge head according to claim 6, wherein the second position is closer to the end of the first electrode than the first position. The wiring includes a first wiring for applying a voltage to the first electrode and a second wiring for applying a voltage to the second electrode.
The liquid discharge head according to any one of claims 1 to 5, wherein the first wiring is provided at the first position, and the second wiring is provided at the second position. In the first wiring, a constant holding signal is applied to the first electrode regardless of the amount of liquid discharged.
The liquid discharge head according to any one of claims 6 to 8, wherein the second wiring applies a different drive signal to the second electrode according to a liquid discharge amount. The first wiring is
The first wiring part extending in the first direction and
Any of claims 6 to 9, wherein a second wiring portion provided at a position different from the first wiring portion in the second direction intersecting the first direction and extending in the first direction is included. The liquid discharge head according to item 1. The liquid discharge head according to claim 10, wherein the wiring is not provided in at least a part between the first wiring portion and the second wiring portion. The piezoelectric body includes a first piezoelectric body and a second piezoelectric body provided at a position different from that of the first piezoelectric body.
The first electrode is provided in common with respect to the first piezoelectric body and the second piezoelectric body.
The liquid discharge head according to any one of claims 1 to 11, wherein the second electrode is individually provided for the first piezoelectric body and the second piezoelectric body. The liquid discharge head according to any one of claims 1 to 12.
A liquid discharge device including a control unit that controls the operation of the liquid discharge head.

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