Liquid discharge head

Abstract

To improve the displacement efficiency of a diaphragm.SOLUTION: Provided is a liquid discharge head that includes: a plurality of pressure chambers arranged side by side in a first direction and extending in a second direction; a piezoelectric body provided for each of the pressure chambers; a common electrode located above the piezoelectric body and provided in common for the plurality of pressure chambers; and individual electrodes located below the piezoelectric bodies and provided individually for the plurality of pressure chambers; wherein when the central position in the second direction within the pressure chamber is defined as a first position, and the position closer to the end than the first position in the second direction within the pressure chamber is defined as a second position, the width of the individual electrode in the first direction at the first position is a first width, and the width of the individual electrode in the first direction at the second position is a second width that is smaller than the first width.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present disclosure relates to a liquid ejection head.

Background Art

[0002] Patent Document 1 discloses a liquid ejection head in which a lower electrode film, a piezoelectric layer, and an upper electrode film are laminated on a diaphragm in this order.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the configuration described in Patent Document 1, since the width of the lower electrode film is constant over the entire length in the length direction, the capacitance of the piezoelectric layer in a portion that contributes less to the displacement of the diaphragm increases. For this reason, there is a problem that the displacement efficiency of the diaphragm cannot be sufficiently increased.

Means for Solving the Problems

[0005] One aspect of the liquid ejection head according to the present disclosure includes a plurality of pressure chambers arranged side by side in a first direction and each extending in a second direction, a piezoelectric body provided for each of the pressure chambers, a common electrode located above the piezoelectric body and provided in common for the plurality of pressure chambers, and an individual electrode located below the piezoelectric body and provided individually for the plurality of pressure chambers. When the central position in the second direction in the pressure chamber is a first position and the position closer to the end side than the first position in the second direction in the pressure chamber is a second position, the width in the first direction of the individual electrode at the first position is a first width, and the width in the first direction of the individual electrode at the second position is a second width smaller than the first width.

Brief Description of the Drawings

[0006]

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[0007] Hereinafter, preferred embodiments according to the present disclosure will be described with reference to the accompanying drawings. Note that the dimensions or scales of each part in the drawings are appropriately different from the actual ones, and there are also parts schematically shown for easy understanding. Also, the scope of the present disclosure is not limited to these embodiments unless otherwise specifically stated in the following description.

[0008] In the following description, the X-axis, Y-axis, and Z-axis that intersect each other are appropriately used. Also, one direction along the X-axis is referred to as the X1 direction, and the direction opposite to the X1 direction is referred to as the X2 direction. The direction along the X-axis, that is, the X1 direction or the X2 direction, is an example of the "second direction". Similarly, the directions opposite to each other along the Y-axis are referred to as the Y1 direction and the Y2 direction. The direction along the Y-axis, that is, the Y1 direction or the Y2 direction, is an example of the "first direction". Also, the directions opposite to each other along the Z-axis are referred to as the Z1 direction and the Z2 direction. The Z1 direction or the Z2 direction is an example of the "third direction". Also, looking in the direction along the Z-axis is referred to as "plan view".

[0009] Here, typically, the Z-axis is a vertical axis, and the Z2 direction corresponds to the downward direction in the vertical direction. However, the Z-axis does not have to be a vertical axis. Also, the X-axis, Y-axis, and Z-axis typically intersect at right angles to each other, but are not limited to this, and for example, they may intersect at an angle within the range of 80° or more and 100° or less.

[0010] 1. Embodiment 1-1. Overall Configuration of Liquid Discharge Device FIG. 1 is a configuration diagram schematically showing a liquid discharge device 100 according to the first embodiment. The liquid discharge device 100 is an inkjet printing device that discharges ink, which is an example of a liquid, as droplets onto a medium 12. The medium 12 is typically printing paper. Note that the medium 12 is not limited to printing paper, and for example, it may be a printing target of any material such as a resin film or fabric.

[0011] As shown in FIG. 1, the liquid discharge device 100 includes a liquid container 14, a control unit 20, a conveyance mechanism 22, a moving mechanism 24, and a liquid discharge head 26.

[0012] The control unit 20 includes, for example, a processing circuit such as a CPU (Central Processing Unit) or an FPGA (Field Programmable Gate Array), and a storage circuit such as a semiconductor memory, and controls the operations of the respective elements of the liquid ejection device 100. Here, the control unit 20 is an example of a "control section" and controls the ink ejection operation by the liquid ejection head 26.

[0013] The liquid container 14 is a container that stores ink. Specific examples of the liquid container 14 include, for example, a cartridge that is detachable from the liquid ejection device 100, a bag-shaped ink pack formed of a flexible film, and an ink tank that can be refilled with ink. The type of ink stored in the liquid container 14 is arbitrary.

[0014] The conveyance mechanism 22 conveys the medium 12 in the Y2 direction under the control of the control unit 20. The moving mechanism 24 reciprocates the liquid ejection head 26 in the X1 direction and the X2 direction under the control of the control unit 20. In the example shown in FIG. 1, the moving mechanism 24 includes a substantially box-shaped carrier 242 called a carriage that houses the liquid ejection head 26, and a conveyor belt 244 to which the carrier 242 is fixed. The number of liquid ejection heads 26 mounted on the carrier 242 is not limited to one, and a plurality of them may be provided. Further, in addition to the liquid ejection head 26, the aforementioned liquid container 14 may be mounted on the carrier 242.

[0015] The liquid ejection head 26 ejects ink supplied from the liquid container 14 in the Z2 direction from each of a plurality of nozzles toward the medium 12 under the control of the control unit 20. By performing this ejection in parallel with the conveyance of the medium 12 by the conveyance mechanism 22 and the reciprocating movement of the liquid ejection head 26 by the moving mechanism 24, an image made of ink is formed on the surface of the medium 12.

[0016] 1-2. Overall Configuration of Liquid Ejection Head FIG. 2 is an exploded perspective view of the liquid ejection head 26 according to the first embodiment. FIG. 3 is a cross-sectional view taken along line A-A of FIG. 2. As shown in FIGS. 2 and 3, the liquid ejection head 26 includes a flow path substrate 32, a pressure chamber substrate 34, a diaphragm 36, a plurality of piezoelectric elements 38, a housing portion 42, a sealing member 44, a nozzle plate 46, a vibration absorber 48, and a wiring substrate 50. Note that the actuator 30 is constituted by the pressure chamber substrate 34, the diaphragm 36, and the plurality of piezoelectric elements 38.

[0017] Here, the pressure chamber substrate 34, the diaphragm 36, the plurality of piezoelectric elements 38, the housing portion 42, and the sealing member 44 are installed in a region located in the Z1 direction with respect to the flow path substrate 32. On the other hand, the nozzle plate 46 and the vibration absorber 48 are installed in a region located in the Z2 direction with respect to the flow path substrate 32. Each element of the liquid ejection head 26 is a plate-like member that is generally long in the Y direction, and is joined to each other by, for example, an adhesive.

[0018] As shown in FIG. 2, the nozzle plate 46 is a plate-like member provided with a plurality of nozzles N arranged in a direction along the Y axis. Each nozzle N is a through hole through which ink passes. The nozzle plate 46 is manufactured, for example, by processing a single-crystal silicon substrate using semiconductor manufacturing technology such as dry etching or wet etching. However, other known methods and materials may be appropriately used for manufacturing the nozzle plate 46.

[0019] The flow path substrate 32 is a plate-like member for forming an ink flow path. As shown in FIGS. 2 and 3, the flow path substrate 32 is provided with an opening 322, a plurality of supply flow paths 324, a plurality of communication flow paths 326, and a relay flow path 328. The opening 322 is an elongated through-hole that extends in the direction along the Y-axis in a plan view when viewed in the direction along the Z-axis so as to be continuous across the plurality of nozzles N. On the other hand, each of the supply flow path 324 and the communication flow path 326 is a through-hole provided individually for each nozzle N. As shown in FIG. 3, the relay flow path 328 is provided on the surface of the flow path substrate 32 facing the Z2 direction. The relay flow path 328 is provided across the plurality of supply flow paths 324 and is a flow path that connects the opening 322 and the plurality of supply flow paths 324. Similar to the aforementioned nozzle plate 46, the flow path substrate 32 is manufactured, for example, by processing a silicon single crystal substrate using semiconductor manufacturing technology. However, other known methods and materials may be appropriately used for the manufacture of the flow path substrate 32.

[0020] The pressure chamber substrate 34 is a plate-like member in which a plurality of pressure chambers C corresponding to the plurality of nozzles N are formed. The pressure chamber C is located between the flow path substrate 32 and the diaphragm 36 and is a space called a cavity for applying pressure to the ink filled in the pressure chamber C. The plurality of pressure chambers C are arranged side by side in the direction along the Y-axis. Each pressure chamber C is partitioned by holes 341 that open on both sides of the pressure chamber substrate 34 and has an elongated shape extending in the direction along the X-axis. The end of each pressure chamber C in the X2 direction communicates with the corresponding supply flow path 324. On the other hand, the end of each pressure chamber C in the X1 direction communicates with the corresponding communication flow path 326. Thus, the liquid ejection head 26 has a plurality of pressure chambers C. Similar to the aforementioned nozzle plate 46, the pressure chamber substrate 34 is manufactured, for example, by processing a silicon single crystal substrate using semiconductor manufacturing technology. However, other known methods and materials may be appropriately used for the manufacture of each of the pressure chamber substrates 34.

[0021] On the surface of the pressure chamber substrate 34 facing the Z1 direction, the diaphragm 36 is disposed. The diaphragm 36 is a plate-like member that can be elastically deformed. In the example shown in FIG. 3, the diaphragm 36 has a first layer 361 that is an elastic film and a second layer 362 that is an insulating film, and these are laminated in the Z1 direction in this order. The first layer 361 is an elastic film made of, for example, silicon oxide (SiO2). The elastic film is formed, for example, by thermally oxidizing one surface of a single crystal silicon substrate. The second layer 362 is an insulating film made of, for example, zirconium oxide (ZrO2). The insulating film is formed, for example, by forming a zirconium layer by sputtering and thermally oxidizing the layer.

[0022] Note that the first layer 361 is not limited to silicon oxide, and may be made of other elastic materials such as single crystal silicon. The constituent material of the second layer 362 is not limited to zirconium oxide, and may be other insulating materials such as silicon nitride. Also, other layers such as metal oxides may be interposed between the first layer 361 and the second layer 362. In other words, the first layer 361 or the second layer 362 may be composed of a plurality of layers that are the same as or different from each other. Also, part or all of the diaphragm 36 may be integrally formed of the same material as the pressure chamber substrate 34. Also, the diaphragm 36 may be composed of a layer of a single material.

[0023] On the surface of the diaphragm 36 facing the Z1 direction, a plurality of piezoelectric elements 38 corresponding to different nozzles N or pressure chambers C are disposed. Each piezoelectric element 38 is a passive element that deforms by the supply of a drive signal, and has an elongated shape extending in a direction along the X axis. The plurality of piezoelectric elements 38 are arranged in a direction along the Y axis so as to correspond to the plurality of pressure chambers C. When the diaphragm 36 vibrates in conjunction with the deformation of the piezoelectric element 38, the pressure in the pressure chamber C fluctuates, whereby the ink is ejected from the nozzle N. Details of the piezoelectric element 38 will be described later with reference to FIGS. 4 to 6.

[0024] The housing part 42 is a case for storing ink supplied to a plurality of pressure chambers C, and is joined to the surface of the flow path substrate 32 facing the Z1 direction by an adhesive or the like. The housing part 42 is made of, for example, a resin material and is manufactured by injection molding. The housing part 42 is provided with a housing part 422 and an inlet 424. The housing part 422 is a recess having an outer shape corresponding to the opening 322 of the flow path substrate 32. The inlet 424 is a through hole communicating with the housing part 422. The space formed by the opening 322 and the housing part 422 functions as a liquid storage chamber R which is a reservoir for storing ink. Ink from the liquid container 14 is supplied to the liquid storage chamber R through the inlet 424.

[0025] The vibration absorber 48 is an elastically deformable flexible sheet member for absorbing pressure fluctuations in the liquid storage chamber R, and is also referred to as a compliance substrate. The vibration absorber 48 is disposed on the surface of the flow path substrate 32 facing the Z2 direction so as to block the opening 322, the relay flow path 328, and the plurality of supply flow paths 324 of the flow path substrate 32 and form the bottom surface of the liquid storage chamber R.

[0026] The sealing body 44 is a structure that protects a plurality of piezoelectric elements 38 and reinforces the mechanical strength of the pressure chamber substrate 34 and the diaphragm 36. The sealing body 44 is joined to the surface of the diaphragm 36 by, for example, an adhesive. The sealing body 44 is provided with recesses for accommodating a plurality of piezoelectric elements 38.

[0027] A wiring substrate 50 is joined to the surface of the pressure chamber substrate 34 or the diaphragm 36 facing the Z1 direction. The wiring substrate 50 is a mounting component on which a plurality of wirings for electrically connecting the control unit 20 and the liquid ejection head 26 are formed. The wiring substrate 50 is a flexible wiring substrate such as, for example, an FPC (Flexible Printed Circuit) or an FFC (Flexible Flat Cable). A drive signal for driving the piezoelectric element 38 is supplied to the wiring substrate 50. The drive signal is supplied to each piezoelectric element 38 via the wiring substrate 50.

[0028] 1-3. Details of the Piezoelectric Element FIG. 4 is a cross-sectional view of the actuator 30 of the liquid ejection head 26 according to the first embodiment. FIG. 5 is a cross-sectional view taken along line B-B in FIG. 4. In these figures, the configuration of the actuator 30 is shown in more detail than in FIGS. 2 and 3 described above.

[0029] As shown in FIG. 4, the actuator 30 includes a pressure chamber substrate 34, a diaphragm 36, a plurality of piezoelectric elements 38, a wiring layer 54, a weight layer 55, and a weight layer 56. Here, in the actuator 30, the pressure chamber substrate 34, the diaphragm 36, and the plurality of piezoelectric elements 38 are laminated in this order in the Z1 direction as described above, and the wiring layer 54, the weight layer 55, and the weight layer 56 are the layers located most in the Z1 direction and are obtained by the same film formation process.

[0030] As shown in FIGS. 4 and 5, the pressure chamber substrate 34 is provided with holes 341 that form the pressure chambers C. The pressure chamber substrate 34 is formed, for example, by anisotropically etching a single-crystal silicon substrate. For the etching solution for the anisotropic etching, for example, an aqueous potassium hydroxide solution (KOH) or the like is used. In the anisotropic etching, the first layer 361 of the diaphragm 36 is used as an etching stop layer.

[0031] In this way, the pressure chamber substrate 34 is made of single-crystal silicon and partitions a plurality of pressure chambers C.

[0032] The piezoelectric element 38 overlaps the pressure chamber C in plan view. The piezoelectric element 38 has an individual electrode 381, a piezoelectric body 382, and a common electrode 383, and these are laminated in this order in the Z1 direction. Therefore, the liquid ejection head 26 has the piezoelectric body 382, the common electrode 383, and the individual electrode 381.

[0033] Note that other layers such as a layer for enhancing adhesion may be appropriately interposed between the layers of the piezoelectric element 38 or between the piezoelectric element 38 and the diaphragm 36. Also, a seed layer may be provided between the individual electrode 381 and the piezoelectric body 382. The seed layer has a function of improving the orientation of the piezoelectric body 382 when the piezoelectric body 382 is formed, and is composed of, for example, titanium (Ti) or a complex oxide having a perovskite structure such as Pb(Fe,Ti)O3.

[0034] The individual electrode 381 is an electrode that is arranged separately from each other for each piezoelectric element 38. That is, the individual electrode 381 is located below the piezoelectric body 382 and is provided individually for the plurality of pressure chambers C. Specifically, a plurality of individual electrodes 381 extending in the direction along the X axis are arranged at intervals in the direction along the Y axis. A drive signal for discharging ink from the nozzle N corresponding to the piezoelectric element 38 is applied to the individual electrode 381 of each piezoelectric element 38 via the wiring board 50.

[0035] The individual electrode 381 has, for example, a first layer made of titanium (Ti), a second layer made of platinum (Pt), and a third layer made of iridium (Ir), and these are laminated in this order in the Z1 direction. The individual electrode 381 is formed by, for example, a known film formation technique such as a sputtering method and a known processing technique using photolithography and etching.

[0036] Note that the configuration of the individual electrode 381 is not limited to the above example. For example, either the second layer or the third layer described above may be omitted, or a layer made of iridium may be further provided between the first layer and the second layer described above. Also, instead of or in addition to the second layer and the third layer, a layer made of an electrode material other than iridium and platinum may be used. Examples of the electrode material include metal materials such as aluminum (Al), nickel (Ni), gold (Au), and copper (Cu), and among these, one kind may be used alone, or two or more kinds may be used in combination in the form of lamination or alloy.

[0037] The above individual electrode 381 is drawn out to a position in the X1 direction from the piezoelectric body 382, and the wiring layer 54 is connected to the individual electrode 381. The wiring layer 54 is a conductive film that extends in the X1 direction from the piezoelectric element 38 for each individual electrode 381, and functions as a wiring that connects the individual electrode 381 and the wiring substrate 50. In the example shown in FIG. 4, the wiring layer 54 has a layer 541 and a layer 542, and these are laminated in the Z1 direction in this order. The layer 541 is a layer for enhancing the adhesion between the wiring layer 54 and the piezoelectric element 38, and is composed of, for example, a nickel-chromium alloy. The layer 542 is a layer for enhancing the conductivity of the wiring layer 54, and is composed of, for example, gold (Au).

[0038] The piezoelectric body 382 is provided for each pressure chamber C and is disposed between the individual electrode 381 and the common electrode 383. The piezoelectric body 382 is composed of a piezoelectric material having a perovskite crystal structure represented by the general composition formula ABO3. Examples of the piezoelectric material include lead titanate (PbTiO3), lead zirconate titanate (Pb(Zr,Ti)O3), lead zirconate (PbZrO3), lead lanthanum titanate ((Pb,La),TiO3), lead lanthanum zirconate titanate ((Pb,La)(Zr,Ti)O3), lead zirconium titanate niobate (Pb(Zr,Ti,Nb)O3), lead zirconium titanate magnesium niobate (Pb(Zr,Ti)(Mg,Nb)O3), and the like. Among them, lead zirconate titanate is preferably used as the constituent material of the piezoelectric body 382. Note that the piezoelectric body 382 may contain a small amount of other elements such as impurities. Further, the piezoelectric material constituting the piezoelectric body 382 may be a non-lead material such as barium titanate.

[0039] The piezoelectric body 382 is formed, for example, by forming a precursor layer of the piezoelectric body by a liquid phase method such as the sol-gel method or the MOD (metal organic decomposition) method, and firing and crystallizing the precursor layer. Here, the piezoelectric body 382 may be composed of a single layer, but when it is composed of a plurality of layers, there is an advantage that even if the thickness of the piezoelectric body 382 is increased, the characteristics of the piezoelectric body 382 can be easily enhanced.

[0040] The width WP of the piezoelectric body 382 in the direction along the Y-axis is smaller than the width WC of the pressure chamber C in the direction along the Y-axis. Here, when looking in the direction along the Z-axis, at both ends of the pressure chamber C in the direction along the Y-axis, there are portions that do not overlap with the piezoelectric body 382. In the following, such a portion may be referred to as an arm portion. Also, the width of such a portion in the direction along the Y-axis may be referred to as the arm width WA.

[0041] The common electrode 383 is a strip-shaped common electrode that extends in the direction along the Y-axis so as to be continuous across a plurality of piezoelectric elements 38. That is, the common electrode 383 is located above the piezoelectric body 382 and is provided in common for a plurality of pressure chambers C. A predetermined reference voltage is applied to the common electrode 383.

[0042] The common electrode 383 has, for example, a layer made of iridium (Ir) and a layer made of titanium (Ti), and these are laminated in this order in the Z1 direction. The common electrode 383 is formed by, for example, a known film formation technique such as a sputtering method and a known processing technique using photolithography and etching or the like.

[0043] Note that the constituent material of the common electrode 383 is not limited to iridium and titanium, and may be, for example, a metal material such as platinum (Pt), aluminum (Al), nickel (Ni), gold (Au), or copper (Cu). Also, the common electrode 383 may be configured by using one of these metal materials alone, or may be configured by combining two or more of them in the form of lamination or alloy. Also, the common electrode 383 may be configured as a single layer. However, it is preferable that the common electrode 383 contains iridium or iridium oxide having an oxygen content less than the stoichiometric composition.

[0044] On the above common electrode 383, a weight layer 55 and a weight layer 56 are arranged. The weight layer 55 and the weight layer 56 are weights for suppressing unnecessary vibrations of the diaphragm 36. Specifically, the weight layer 55 is a strip-shaped conductive film extending along the Y axis along the edge of the common electrode 383 in the X1 direction, and is formed of gold (Au) as an example. In the example shown in FIG. 5, the weight layer 55 has a layer 551 obtained by the same film formation process as the layer 541 and a layer 552 obtained by the same film formation process as the layer 542, and these are stacked in the Z1 direction in this order. The weight layer 56 is a strip-shaped conductive film extending along the Y axis along the edge of the common electrode 383 in the X2 direction. In the example shown in FIG. 4, the weight layer 55 has a layer 551 obtained by the same film formation process as the layer 541 and a layer 552 obtained by the same film formation process as the layer 542, and these are stacked in the Z1 direction in this order.

[0045] In the piezoelectric element 38 having the above basic configuration, the individual electrode 381 is composed of a plurality of portions with different widths so as to increase the displacement efficiency of the diaphragm 36. In the present embodiment, from the viewpoint of not only increasing the displacement efficiency of the diaphragm 36 but also suppressing the occurrence of cracks in the diaphragm 36, the piezoelectric body 382 is composed of a plurality of portions with different widths.

[0046] FIG. 6 is a diagram for explaining the individual electrode 381 in the first embodiment. In FIG. 6, the individual electrode 381 as viewed in the Z2 direction is shown. In FIG. 6, in addition to the individual electrode 381, the elements of the flow path substrate 32 and the pressure chamber substrate 34 are shown by broken lines, and the elements of the piezoelectric body 382 are shown by two-dot chain lines.

[0047] In the example shown in FIG. 6, the planar shape of the hole 341 partitioning the pressure chamber C is a shape generally along a parallelogram. Such a hole 341 having such a planar shape is formed, for example, by anisotropically etching a silicon single crystal substrate having a plane orientation of (110). That is, the outer shape of the hole 341 in plan view is composed of a plurality of sides along the crystal plane of the silicon single crystal with a plane orientation of (110). Note that the planar shape of the hole 341 is not limited to the example shown in FIG. 6 and is arbitrary.

[0048] The individual electrode 381 has a first portion 381a, a second portion 381b, a third portion 381c, and a fourth portion 381d. These portions are arranged in the order of the second portion 381b, the first portion 381a, the third portion 381c, and the fourth portion 381d in the X1 direction.

[0049] The first portion 381a, the second portion 381b, and the third portion 381c are part of the individual electrode 381 and are portions that overlap the pressure chamber C in plan view. Here, the first portion 381a is disposed between the second portion 381b and the third portion 381c and is provided over a range including the first position P1 in the X1 direction or the second direction. The second portion 381b is disposed at a position in the X2 direction with respect to the first portion 381a and is provided over a range including the second position P2 in the X1 direction or the X2 direction. On the other hand, the third portion 381c is disposed at a position in the X1 direction with respect to the first portion 381a and is provided over a range including the third position P3 in the X1 direction or the X2 direction.

[0050] The first position P1 is the central position in the X1 direction or the X2 direction within the pressure chamber C. The second position P2 is a position closer to the end side than the first position P1 in the X1 direction or the X2 direction within the pressure chamber C. The third position P3 is a position closer to the end side opposite to the second position P2 than the first position P1 in the X1 direction or the X2 direction within the pressure chamber C.

[0051] The first portion 381a is a portion with a first width W1. That is, the width of the first portion 381a in the Y1 direction or the Y2 direction is the first width W1. In contrast, each of the second portion 381b and the third portion 381c is a portion with a second width W2 smaller than the first width W1. That is, the width of each of the second portion 381b and the third portion 381c in the Y1 direction or the Y2 direction is the second width W2 smaller than the first width W1.

[0052] Thus, the width of the individual electrode 381 in the Y1 direction or the Y2 direction at the first position P1 is the first width W1, while the width of the individual electrode 381 in the Y1 direction or the Y2 direction at the second position P2 is the second width W2 that is smaller than the first width W1. Thereby, the displacement efficiency of the diaphragm 36 can be improved. Also, since the width of the individual electrode 381 in the Y1 direction or the Y2 direction at the third position P3 is the second width W2 that is smaller than the first width W1, the displacement efficiency of the diaphragm 36 can also be improved in this regard.

[0053] The second width W2 is preferably 90% or more and 95% or less of the first width W1. When the second width W2 is within such a range, the displacement efficiency of the diaphragm 36 can be suitably improved.

[0054] The length L1 of the first portion 381a in the X1 direction or the X2 direction is preferably longer than the length L2 of the second portion 381b in the X1 direction or the X2 direction. Thereby, the displacement efficiency of the diaphragm 36 can be suitably improved.

[0055] Similarly, the length L1 of the first portion 381a in the X1 direction or the X2 direction is preferably longer than the length L3 of the third portion 381c in the X1 direction or the X2 direction. Thereby, the displacement efficiency of the diaphragm 36 can be suitably improved.

[0056] The length L1 of the first portion 381a in the X1 direction or the X2 direction is preferably 40% or more and 60% or less of the length L of the pressure chamber C in the X1 direction or the X2 direction. Thereby, the displacement efficiency of the diaphragm 36 can be suitably improved.

[0057] The width of the piezoelectric body 382 at the first position P1 is the third width W3. In contrast, the width of the piezoelectric body 382 at the second position P2 is the fourth width W4 that is smaller than the third width W3. Thereby, the occurrence of cracks in the diaphragm 36 can be suppressed.

[0058] In the example shown in FIG. 6, the piezoelectric body 382 has a strip shape extending in the direction along the Y-axis so as to be continuous across the plurality of piezoelectric elements 38. In the piezoelectric body 382, through holes 382a penetrating the piezoelectric body 382 are provided in regions corresponding in plan view to the gaps between the pressure chambers C adjacent to each other, and extend in the direction along the X-axis. Since the width of the through hole 382a at the first position P1 is smaller than the width of the through hole 382a at the second position P2, the fourth width W4 is smaller than the third width W3. Note that the piezoelectric body 382 may be provided individually for the plurality of piezoelectric elements 38.

[0059] The pressure chamber substrate 34 is provided with a throttle portion AP that communicates the pressure chamber C and the nozzle. The throttle portion AP is partitioned by the hole 341 together with the pressure chamber C, and is formed to be narrower than the pressure chamber C. The pressure chamber C communicates with the communication flow path 326 through the throttle portion AP. In the present embodiment, a part of the third portion 381c and the fourth portion 381d overlap the throttle portion AP when viewed in the direction along the Z-axis. The width of the fourth portion 381d is the fourth width W4 that is narrower than the second width W2.

[0060] FIG. 7 is a diagram showing the relationship between the arm width WA and the displacement efficiency of the diaphragm 36. As shown in FIG. 7, the displacement efficiency of the diaphragm 36 by the piezoelectric element 38 can be increased as compared with the mode in which the arm portion is not provided on the diaphragm 36. However, the displacement efficiency of the diaphragm 36 by the piezoelectric element 38 varies depending on the size of the arm width WA. In the example shown in FIG. 7, when the arm width WA is about 6 μm, the displacement efficiency of the diaphragm 36 is the highest. Also, in the range where the arm width WA is less than 6 μm, as the arm width WA increases, the displacement efficiency of the diaphragm 36 increases. This is because the diaphragm 36 is more easily deformed. On the other hand, in the range where the arm width WA exceeds 6 μm, as the arm width WA increases, the displacement efficiency of the diaphragm 36 decreases. This is because the displacement amount of the piezoelectric element 38 decreases.

[0061] As understood from the above, in order to increase the displacement efficiency of the diaphragm 36, it is necessary to provide an arm portion with a certain arm width WA on the diaphragm 36.

[0062] FIG. 8 is a diagram showing the relationship between the arm width WA and the maximum principal stress of the diaphragm 36. In FIG. 8, the relationship between the arm width WA and the maximum principal stress of the diaphragm 36 is shown for the case where the width of the pressure chamber C is 45 μm, the case where the width of the pressure chamber C is 50 μm, and the case where the width of the pressure chamber C is 60 μm.

[0063] As shown in FIG. 8, as the arm width WA decreases, the maximum principal stress of the diaphragm 36 increases. When the maximum principal stress of the diaphragm 36 increases, the risk of crack generation in the diaphragm 36 increases. In particular, as shown in FIG. 4 described above, stress tends to concentrate on the diaphragm 36 at the position X on the periphery of the weight layers 55 and 56, so the risk of crack generation in the diaphragm 36 is high.

[0064] Also, the larger the width of the pressure chamber C, that is, the higher the ratio of the width of the piezoelectric body 382 to the width of the pressure chamber C, the greater the maximum principal stress of the diaphragm 36. This is because the displacement amount of the diaphragm 36 increases as the driving force of the piezoelectric element 38 increases.

[0065] Therefore, as described above, by making the width of the piezoelectric body 382 at the second position P2 smaller than the third width W3 and the fourth width W4, the generation of cracks in the diaphragm 36 can be suitably suppressed.

[0066] FIG. 9 is a diagram showing the relationship between the position and displacement in the width direction of the diaphragm 36. In FIG. 9, the displacement of the diaphragm 36 by the first portion 381a is shown by a two-dot chain line, the displacement of the diaphragm 36 when the width of the piezoelectric body 382 is constant at the second width W2 is shown by a one-dot chain line, and the displacement of the diaphragm 36 of the present embodiment is shown by a solid line.

[0067] As described above, since the width of the first portion 381a is the first width W1, while the widths of the second portion 381b and the third portion 381c are both the second width W2 smaller than the first width W1, the displacement of the diaphragm 36 of the present embodiment is such that the displacements shown by the two-dot chain line and the one-dot chain line in the figure are added together. In this way, the displacement efficiency of the diaphragm 36 can be improved.

[0068] 2. Second Embodiment Hereinafter, the second embodiment of the present disclosure will be described. For elements having the same actions and functions as those in the first embodiment in the embodiments illustrated below, the reference numerals used in the description of the first embodiment are reused, and the detailed description of each is omitted as appropriate.

[0069] FIG. 10 is a diagram for explaining the individual electrode 381 of the liquid ejection head 26A according to the second embodiment. The liquid ejection head 26A is configured in the same manner as the liquid ejection head 26 of the first embodiment, except that it includes a piezoelectric body 382A instead of the piezoelectric body 382 of the first embodiment.

[0070] The piezoelectric body 382A is configured in the same manner as the piezoelectric body 382 of the first embodiment, except that the width at the second position P2 is the third width W3.

[0071] That is, the widths of the piezoelectric body 382A at the first position P1 and the piezoelectric body 382A at the second position P2 are both the third width W3. Thus, compared with the aspect in which the width of the piezoelectric body 382 at the first position P1 is different from the width at the second position P2 as in the first embodiment, the manufacturing of the piezoelectric body 382A becomes easier.

[0072] Also according to the above second embodiment, the displacement efficiency of the diaphragm 36 can be improved.

[0073] 3. Third Embodiment Hereinafter, the third embodiment of the present disclosure will be described. For elements having the same actions and functions as those in the first embodiment in the embodiments illustrated below, the reference numerals used in the description of the first embodiment are reused, and the detailed description of each is omitted as appropriate.

[0074] FIG. 11 is a diagram for explaining the individual electrode 381B of the liquid ejection head 26B according to the third embodiment. The liquid ejection head 26B is configured in the same manner as the liquid ejection head 26 of the first embodiment, except that it includes an individual electrode 381B instead of the individual electrode 381 of the first embodiment.

[0075] The individual electrode 381B is configured in the same manner as the individual electrode 381 of the first embodiment, except that a portion 381e is added. The portion 381e is a part of the individual electrode 381B and extends in the X2 direction from the second portion 381b. The portion 381e has a shape in which the width continuously decreases as it goes in the X2 direction. Here, the portion 381e has a side EG along one side of the supply channel 324 when viewed in the direction along the Z axis.

[0076] The side EG is inclined with respect to the X axis and the Y axis when viewed in the direction along the Z axis, and extends along the crystal plane of the single crystal silicon constituting the pressure chamber substrate 34. Thereby, the area of the individual electrode 381B can be reduced without affecting the overall excluded volume. As a result, the displacement efficiency of the diaphragm 36 can be further improved.

[0077] Also according to the above-described third embodiment, the displacement efficiency of the diaphragm 36 can be improved.

[0078] 4. Fourth Embodiment Hereinafter, a fourth embodiment of the present disclosure will be described. For elements whose actions and functions are the same as those of the first embodiment in the forms exemplified below, the reference numerals used in the description of the first embodiment are borrowed and the detailed description of each is appropriately omitted.

[0079] FIG. 12 is a diagram for explaining an individual electrode 381C of a liquid ejection head 26C according to the fourth embodiment. The liquid ejection head 26C is configured in the same manner as the liquid ejection head 26 of the first embodiment, except that it includes an individual electrode 381C instead of the individual electrode 381 of the first embodiment.

[0080] The individual electrode 381C is configured in the same manner as the individual electrode 381 of the first embodiment, except that it has a third portion 381f and a fourth portion 381g instead of the third portion 381c and the fourth portion 381d of the first embodiment.

[0081] The third part 381f is configured in the same manner as the third part 381c of the first embodiment, except that it has a length that fits within the pressure chamber C when viewed in the direction along the Z-axis. The fourth part 381g is configured in the same manner as the fourth part 381d of the first embodiment, except that it extends in the X1 direction from the third part 381f.

[0082] Here, the fourth part 381g overlaps the boundary between the throttle portion AP and the pressure chamber C when viewed in the direction along the Z-axis. Also, the width of the fourth part 381g is a fourth width W4 that is narrower than the second width W2, similar to the fourth part 381d of the first embodiment. Thereby, the area of the individual electrode 381C can be reduced without affecting the overall exclusion volume. As a result, the displacement efficiency of the diaphragm 36 can be further improved.

[0083] Also, according to the above fourth embodiment, the displacement efficiency of the diaphragm 36 can be improved.

[0084] 5. Modifications Each of the forms in the above examples can be variously modified. Specific forms of modification applicable to each of the above forms are exemplified below. Note that two or more forms arbitrarily selected from the following examples can be appropriately combined within a range that does not conflict with each other.

[0085] 5-1. Modification 1 FIG. 13 is a diagram for explaining the individual electrode 381D of the liquid ejection head 26D according to Modification 1. The liquid ejection head 26D is configured in the same manner as the liquid ejection head 26 of the first embodiment, except that the shape of the hole 341 is different and it is provided with an individual electrode 381D instead of the individual electrode 381 of the first embodiment.

[0086] In this embodiment, the hole 341 delimits a throttle portion AP1 together with the pressure chamber C. The throttle portion AP1 is a portion narrower in width than the pressure chamber C and communicates the pressure chamber C with the supply flow path 324. Thereby, the pressure chamber C communicates with the supply flow path 324 via the throttle portion AP1.

[0087] The individual electrode 381D is configured in the same manner as the individual electrode 381 of the first embodiment, except that it has the side EG, similar to the third embodiment.

[0088] Also by the above Modification 1, the displacement efficiency of the diaphragm 36 can be improved.

[0089] 5-2. Modification 2 In each of the above-described embodiments, the serial liquid ejection apparatus 100 that reciprocates the carrier 242 on which the liquid ejection head 26 is mounted is exemplified. However, the present disclosure can also be applied to a line-type liquid ejection apparatus in which a plurality of nozzles N are distributed over the entire width of the medium 12.

[0090] 5-3. Modification 3 The liquid ejection apparatus 100 exemplified in each of the above-described embodiments can be adopted in various apparatuses such as a facsimile apparatus and a copying machine, in addition to an apparatus dedicated to printing. However, the use of the liquid ejection apparatus of the present disclosure is not limited to printing. For example, a liquid ejection apparatus that ejects a solution of a coloring material is used as a manufacturing apparatus for forming a color filter of a liquid crystal display device. Also, a liquid ejection apparatus that ejects a solution of a conductive material is used as a manufacturing apparatus for forming wirings and electrodes of a wiring substrate.

Description of Reference Numerals

[0091] 12… Medium, 14… Liquid container, 20… Control unit, 22… Conveying mechanism, 24… Moving mechanism, 26… Liquid ejection head, 26A… Liquid ejection head, 26B… Liquid ejection head, 26C… Liquid ejection head, 26D… Liquid ejection head, 30… Actuator, 32… Flow path substrate, 34… Pressure chamber substrate, 36… Diaphragm, 38… Piezoelectric element, 42… Housing part, 44… Sealing body, 46… Nozzle plate, 48… Vibration absorber, 50… Wiring substrate, 54… Wiring layer, 55… Weight layer, 56… Weight layer, 100… Liquid ejection device, 242… Carrier, 244… Conveyor belt, 322… Opening, 324… Supply flow path, 326… Communication flow path, 328… Relay flow path, 341… Hole, 361… First layer, 362… Second layer, 381… Individual electrode, 381B… Individual electrode, 381C… Individual electrode, 381D… Individual electrode, 381a… First part, 381b… Second part, 381c… Third part, 381d… Fourth part, 381e… Part, 381f… Third part, 381g… Fourth part, 382… Piezoelectric body, 382A… Piezoelectric body, 382a… Through hole, 383… Common electrode, 422… Accommodation part, 424… Inlet, 541… Layer, 542… Layer, 551… Layer, 552… Layer, AP… Throttle part, AP1… Throttle part, C… Pressure chamber, EG… Side, N… Nozzle, P1… First position, P2… Second position, P3… Third position, R… Liquid storage chamber, W1… First width, W2… Second width, W3… Third width, W4… Fourth width, WA… Arm width, WC… Width, WP… Width, X… Position.

Claims

1. A plurality of pressure chambers arranged side by side in a first direction and each extending in a second direction, a piezoelectric body provided for each of the pressure chambers, a common electrode located above the piezoelectric body and provided in common for the plurality of pressure chambers, an individual electrode located below the piezoelectric body and provided individually for the plurality of pressure chambers, a liquid discharge head having: a first position at the central position in the second direction within the pressure chamber, when a position closer to an end side than the first position in the second direction within the pressure chamber is defined as a second position, a width of the individual electrode in the first direction at the first position is a first width, a width of the individual electrode in the first direction at the second position is a second width smaller than the first width, A liquid discharge head characterized by this.

2. The second width is 90% or more and 95% or less of the first width, The liquid discharge head according to claim 1, characterized by this.

3. A width of the piezoelectric body at the first position is a third width, a width of the piezoelectric body at the second position is a fourth width smaller than the third width, The liquid discharge head according to claim 1, characterized by this.

4. A width of the piezoelectric body at the first position is a third width, a width of the piezoelectric body at the second position is the third width, The liquid discharge head according to claim 1, characterized by this.

5. The individual electrode is a first portion of the first width provided over a range including the first position in the second direction, a second portion of the second width provided over a range including the second position in the second direction, and includes, a length of the first portion in the second direction is longer than a length of the second portion in the second direction, The liquid discharge head according to claim 1, characterized by this.

6. The individual electrode is includes a third portion of the second width, the first portion is located between the second portion and the third portion, a length of the first portion in the second direction is longer than a length of the third portion in the second direction, The liquid discharge head according to claim 5, characterized by this.

7. a length of the first portion in the second direction is 40% or more and 60% or less of a length of the pressure chamber in the second direction, The liquid discharge head according to claim 5, characterized by this.

8. Further includes a pressure chamber substrate made of single crystal silicon and partitioning the plurality of pressure chambers, The individual electrode has a side that is inclined with respect to the first direction and the second direction when viewed in a third direction orthogonal to the first direction and the second direction, and extends along a crystal plane of the single crystal silicon. The liquid ejection head according to claim 1, characterized in that.

9. The liquid ejection head further includes a pressure chamber substrate that partitions the plurality of pressure chambers. The pressure chamber substrate is provided with a throttle portion that communicates the pressure chamber and the nozzle. The individual electrode has a fourth portion that overlaps a boundary between the throttle portion and the pressure chamber when viewed in a third direction orthogonal to the first direction and the second direction. The width of the fourth portion is narrower than the second width. The liquid ejection head according to claim 1, characterized in that.

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