Liquid ejection head and liquid ejection device

Abstract

To avoid a high temperature of a drive circuit 42.SOLUTION: A liquid jet head 10 includes: a piezoelectric element 30 that is driven to jet liquid in a jetting direction Z1 from a plurality of nozzles N;individual supply channels 51A that supply liquid to respective nozzles N;individual recovery channels 51B that recover liquid from the respective nozzles N; a pressure chamber 57A communicating with each of the plurality of nozzles N; a vibration plate 26 that defines a wall surface of the plurality of pressure chambers 57A and is displaced by driving of the piezoelectric element 30; a flexible substrate 40 having a drive circuit 42 electrically connected to the piezoelectric element 30;and a heat radiation member 81 that is in contact with a surface 41b on a side opposite to a surface provided with the drive circuit 42 of the flexible substrate 40 or in contact with the drive circuit 42 and conducts heat of the drive circuit 42 to the vibration plate 26.The heat radiation member 81 is disposed closer to the individual supply channels 51A than the individual recovery channels 51B.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to a liquid ejection head and a liquid ejection device.

Background Art

[0002] There is a liquid ejection device having a liquid ejection head that ejects a liquid such as ink. The liquid ejection head described in Patent Document 1 includes a piezoelectric element for ejecting a liquid, a drive circuit having a switching element for driving the piezoelectric element, a wiring member on which the drive circuit is mounted, and a circuit board electrically connected to the wiring member.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Inside the liquid ejection head, the drive circuit is disposed in the space between the piezoelectric element and the circuit board. Heat generated from the drive circuit is transferred by air existing in the space where the drive circuit is disposed or by a metal wiring connected to the drive circuit. However, the heat generated in the drive circuit cannot be sufficiently dissipated to the outside only through the air or the metal wiring, and there is a risk that the drive circuit becomes hot and the drive circuit is damaged. Further, if the performance of the drive circuit is limited in order to avoid damage to the drive circuit, the performance of the liquid ejection head cannot be sufficiently exhibited.

Means for Solving the Problems

[0005] A liquid ejection head according to one aspect of the present invention includes a piezoelectric element that is driven to eject a liquid in an ejection direction from a plurality of nozzles, a plurality of pressure chambers communicating with each of the plurality of nozzles, a plurality of individual supply channels that supply liquid to each of the plurality of nozzles, a plurality of individual recovery channels for recovering liquid that has not been ejected from each of the plurality of nozzles, a diaphragm that defines the wall surfaces of the plurality of pressure chambers and is displaced by driving the piezoelectric element, a flexible substrate having a drive circuit electrically connected to the piezoelectric element, a surface opposite to the surface of the flexible substrate on which the drive circuit is provided, or a heat dissipation member that contacts the drive circuit and conducts the heat of the drive circuit to the diaphragm. The heat dissipation member is disposed closer to the individual supply channels than to the individual recovery channels.

[0006] A liquid ejection device according to one aspect of the present invention includes the above-described liquid ejection head and a liquid storage unit that stores liquid supplied to the liquid ejection head.

Brief Description of the Drawings

[0007]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Embodiments for Carrying Out the Invention

[0008] Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. However, in each figure, the dimensions and scales of each part are appropriately different from the actual ones. Further, the embodiments described below are preferred specific examples of the present invention, and thus various technically preferable limitations are imposed. However, the scope of the present invention is not limited to these embodiments unless otherwise specified in the following description to particularly limit the present invention.

[0009] In the following description, there may be cases where three mutually intersecting directions are described as the X-axis direction, the Y-axis direction, and the Z-axis direction. The X-axis direction includes the X1 direction and the X2 direction, which are opposite directions. The X-axis direction is an example of the second direction. The Y-axis direction includes the Y1 direction and the Y2 direction, which are opposite directions. The Y-axis direction is an example of the first direction. The Z-axis direction includes the Z1 direction and the Z2 direction, which are opposite directions. The Z1 direction is a downward direction, and the Z2 direction is an upward direction. The Z1 direction is an example of the ejection direction. Also, in this specification, "up" and "down" are used. "Up" and "down" correspond to "up" and "down" in the normal use state where the nozzles of the liquid ejection device 1 are below.

[0010] The X-axis direction, the Y-axis direction, and the Z-axis direction are orthogonal. The Z-axis direction is usually a direction along the vertical direction, but the Z-axis direction may not be a direction along the vertical direction.

[0011] FIG. 1 is a schematic diagram showing a configuration example of a liquid ejection device 1 according to the first embodiment. The liquid ejection device 1 is an inkjet printing device that ejects ink, which is an example of "liquid", as droplets onto a medium PA. The liquid ejection device 1 of the present embodiment is a so-called line printer in which a plurality of nozzles for ejecting ink are distributed over the entire range in the width direction of the medium PA. The medium PA is typically printing paper. Note that the medium PA is not limited to printing paper, and may be a printing target made of any material such as a resin film or a fabric, for example.

[0012] As shown in FIG. 1, the liquid ejection device 1 includes a liquid container 2 for storing ink. Specific examples of the liquid container 2 include, for example, a cartridge detachable from the liquid ejection device 1, a bag-shaped ink pack formed of a flexible film, and an ink tank capable of replenishing ink. Note that the type of ink stored in the liquid container 2 is arbitrary. The liquid container 2 is an example of a liquid storage unit.

[0013] There may be one liquid container 2, but although not shown, it usually includes a first liquid container and a second liquid container. The first ink is stored in the first liquid container. A second ink of a type different from the first ink is stored in the second liquid container. For example, the first ink and the second ink are inks of different colors. Note that the first ink and the second ink may be of the same type.

[0014] The liquid ejection device 1 includes a control unit 3, a medium conveyance mechanism 4, a circulation mechanism 5, and a plurality of liquid ejection heads 10. The control unit 3 controls the operations of the respective elements of the liquid ejection device 1. The control unit 3 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. Various programs and various data are stored in the storage circuit. The processing circuit realizes various controls by executing the programs and appropriately using the data.

[0015] The medium conveyance mechanism 4 is controlled by the control unit 3 and conveys the medium PA in the conveyance direction DM. The medium conveyance mechanism 4 includes a long conveyance roller along the width direction of the medium PA and a motor that rotates the conveyance roller. Note that the medium conveyance mechanism 4 is not limited to a configuration using a conveyance roller, and for example, a configuration using a drum or an endless belt that conveys the medium PA in a state where it is adsorbed to the outer peripheral surface by an electrostatic force or the like may also be used.

[0016] The liquid ejection head 10 is controlled by the control unit 3 and ejects ink supplied from the liquid container 2 via the circulation mechanism 5 from each of a plurality of nozzles onto the medium PA. The plurality of liquid ejection heads 10 are arranged in a direction intersecting the conveyance direction DM to form a line head 6.

[0017] The ink stored in the liquid container 2 is supplied to the liquid ejection head 10 via the circulation mechanism 5. The circulation mechanism 5 supplies ink to the liquid ejection head 10 and collects the ink discharged from the liquid ejection head 10. The circulation mechanism 5 supplies the collected ink to the liquid ejection head 10 again. The circulation mechanism 5 includes a flow path for supplying ink to the liquid ejection head 10, a flow path for collecting the ink discharged from the liquid ejection head 10, a sub-tank for storing the collected ink, a pump for transferring the ink, and the like.

[0018] Next, the liquid ejection head 10 will be described with reference to FIG. 2. FIG. 2 is a cross-sectional view showing the liquid ejection head 10. The liquid ejection head 10 includes a plurality of head chips 11, a holder 12 that holds the plurality of head chips 11, a circuit board 13 disposed on the holder 12, and a fixing plate 22 to which the plurality of head chips 11 are fixed. In FIG. 2, a center line O extending in the Z-axis direction and passing through the center in the X-axis direction of an arbitrary head chip 11 among the plurality of head chips 11 held by the holder 12 is shown.

[0019] The head chip 11 includes a nozzle plate 21, a compliance substrate 23, a communication plate 24, a pressure chamber forming plate 25, a diaphragm 26, and a piezoelectric actuator (piezoelectric element) 30. Further, the head chip 11 includes a protective substrate 27, a case 28, and a COF 40. COF is an abbreviation for Chip on Film. In the present embodiment, the holder 12 holds a plurality of head chips 11, but the number of head chips 11 held by the holder 12 may be one. In the present embodiment, the holder 12 is formed of a resin such as PE (polyethylene), PP (polypropylene), or PPS (polyphenylene sulfide).

[0020] The nozzle plate 21 and the compliance substrate 23 are disposed at the bottom of the head chip 11. The communication plate 24 is formed on the nozzle plate 21 and the compliance substrate 23. The pressure chamber forming plate 25 is formed on the communication plate 24. The diaphragm 26 is formed on the pressure chamber forming plate 25. A plurality of piezoelectric actuators 30 are formed on the diaphragm 26. The protective substrate 27 is disposed on the diaphragm 26 so as to cover the plurality of piezoelectric actuators 30. The case 28 is formed on the communication plate 24 so as to cover the protective substrate 27. Other members may be disposed between these members.

[0021] FIG. 3 is a schematic diagram showing the ink flow path 51 in the head chip 11. FIG. 4 is a cross-sectional view showing an enlarged main part of the head chip 11. In FIG. 4, mainly the supply-side flow path of the ink flow path 51 is shown. As shown in FIGS. 2 to 4, a flow path 51 through which ink flows is formed inside the head chip 11. The internal flow path 51 of the head chip 11 includes a supply port 52A, a discharge port 52B, common liquid chambers 53A, 53B, 54A, 54B, relay flow paths 55A, 55B, pressure chambers 57A, 57B, and communication flow paths 58A, 58B, 58C. The nozzle N communicates with the communication flow path 58C. In FIGS. 2 and 4, the illustration of the ink flow path inside the holder 12 is omitted.

[0022] Of the flow path 51, the supply ports 52A, the discharge ports 52B, and the common liquid chambers 53A, 53B are formed in the case 28. The common liquid chambers 53A, 53B are an example of a common flow path. The case 28 is an example of a flow path member having a common flow path. The common liquid chambers 54A, 54B, the relay flow paths 55A, 55B, and the communication flow paths 58A, 58B, 58C are formed in the communication plate 24. The pressure chambers 57A, 57B are formed in the pressure chamber forming plate 25.

[0023] As shown in FIG. 2, the case 28 has common liquid chamber forming portions 71A, 71B, and a cover portion 72. The cover portion 72 is disposed at the central portion of the case 28 in the X-axis direction. The common liquid chamber forming portion 71A is disposed in the X1 direction of the cover portion 72, and the common liquid chamber forming portion 71B is disposed in the X2 direction of the cover portion 72. The common liquid chamber forming portions 71A, 71B protrude in the Z1 direction from the cover portion 72. The case 28 is formed of a resin such as, for example, PE (polyethylene), PP (polypropylene), or PPS (polyphenylene sulfide). The case 28 may be formed of, for example, silicon, may be formed of stainless steel, or may be formed of other metals.

[0024] The cover portion 72 has a rectangular shape when viewed in the Z-axis direction. An opening 73 is formed at the central portion of the cover portion 72 in the X-axis direction. In the Z1 direction of the cover portion 72, a space is formed in which the pressure chamber forming plate 25, the diaphragm 26, the piezoelectric actuator 30, and the protection substrate 27 are disposed.

[0025] The supply port 52A and the common liquid chamber 53A are provided in the common liquid chamber forming portion 71A. The discharge port 52B and the common liquid chamber 53B are provided in the common liquid chamber forming portion 71B. The common liquid chambers 53A, 53B are continuous in the Y-axis direction. The supply port 52A communicates with the common liquid chamber 53A, and the discharge port 52B communicates with the common liquid chamber 53B.

[0026] FIG. 5 is a plan view showing the nozzle plate 21. As shown in FIG. 5, the nozzle plate 21 has a rectangular shape when viewed in the Z-axis direction. A plurality of nozzles N are formed in the nozzle plate 21. The plurality of nozzles N are arranged in the Y-axis direction to form a nozzle row N1.

[0027] In the fixed plate 22 shown in FIGS. 2 and 4, openings are formed so as to surround the nozzle plate 21 when viewed in the Z-axis direction. A plurality of such openings are provided for each of the plurality of head chips 11.

[0028] The compliance substrate 23 is disposed in the Z2 direction of the fixed plate 22. The compliance substrate 23 is disposed so as to surround the nozzle plate 21 when viewed in the Z-axis direction. Common liquid chambers 54A and 54B are disposed in the Z2 direction of the compliance substrate 23.

[0029] The compliance substrate 23 has a flexible film 23a and support plates 23b and 23c. The support plates 23b and 23c are disposed in the Z2 direction of the fixed plate 22. The support plates 23b and 23c are spaced apart from each other in the X-axis direction. A space is formed between the support plates 23b and 23c in the X-axis direction. The flexible film 23a is disposed in the Z2 direction of the support plates 23b and 23c. The flexible film 23a defines the Z1-direction surfaces of the common liquid chambers 54A and 54B. The flexible film 23a absorbs pressure fluctuations in the ink flow path 51 in the head chip 11 by deforming due to the pressure of the ink.

[0030] FIG. 6 is a plan view showing the communication plate 24. In FIG. 6, a view of the communication plate 24 in the Z1 direction is shown. As shown in FIGS. 2 and 6, the communication plate 24 is formed with the common liquid chambers 54A and 54B, the relay flow paths 55A and 55B, and the communication flow paths 58A, 58B, and 58C as described above. In FIG. 6, a dashed-dotted line is illustrated corresponding to the arrangement of the nozzle row N1.

[0031] At the end in the X1 direction, a common liquid chamber 54A is arranged, and at the end in the X2 direction, a common liquid chamber 54B is arranged. The common liquid chambers 54A and 54B are continuous in the Y-axis direction. The common liquid chambers 54A and 54B include an opening penetrating in the Z-axis direction and a groove formed on the surface of the communication plate 24 in the Z1 direction. In FIG. 6, the opening penetrating in the Z-axis direction of the common liquid chambers 54A and 54B is shown by a solid line, and the groove formed on the surface of the common liquid chambers 54A and 54B in the Z1 direction is shown by a broken line. The common liquid chambers 53A and 54A communicate with each other in the Z-axis direction. The common liquid chambers 53B and 54B communicate with each other in the Z-axis direction.

[0032] The relay flow paths 55A and 55B are respectively provided for a plurality of nozzles N. The relay flow paths 55A and 55B extend in the Z-axis direction. The relay flow path 55A extends in the Z2 direction from the end in the X2 direction of the common liquid chamber 54A. The relay flow path 55B extends in the Z2 direction from the end in the X1 direction of the common liquid chamber 54B. The plurality of relay flow paths 55A are arranged at predetermined intervals in the Y-axis direction. The plurality of relay flow paths 55B are arranged at predetermined intervals in the Y-axis direction.

[0033] The relay flow path 55A communicates with the end in the X2 direction of the common liquid chamber 54A. The relay flow path 55A includes an opening penetrating in the Z-axis direction. The pressure chamber 57A communicates with the relay flow path 55A in the Z2 direction.

[0034] The relay flow path 55B communicates with the end in the X1 direction of the common liquid chamber 54B. The relay flow path 55B includes an opening penetrating in the Z-axis direction. The pressure chamber 57B communicates with the relay flow path 55B in the Z2 direction.

[0035] The communication flow path 58A is arranged in the X2 direction of the relay flow path 55A. The communication flow path 58A communicates with the end in the X2 direction of the pressure chamber 57A. The communication flow path 58A extends in the Z1 direction from the pressure chamber 57A. The communication flow path 58A includes an opening penetrating in the Z-axis direction.

[0036] The communication flow path 58B is arranged in the X1 direction of the relay flow path 55B. The communication flow path 58B communicates with the end portion of the pressure chamber 57B in the X1 direction. The communication flow path 58B extends from the pressure chamber 57B in the Z1 direction. The communication flow path 58B includes an opening penetrating in the Z-axis direction.

[0037] The communication flow path 58C extends in the X-axis direction and communicates the communication flow paths 58A and 58B. The plurality of communication flow paths 58C respectively communicate with the plurality of nozzles N.

[0038] The communication plate 24 can be manufactured from, for example, a single crystal silicon substrate. The communication plate 24 may be manufactured from other materials such as metal or ceramics, but when the case 28 and the holder 12 are formed of resin, it is preferably a material having a higher thermal conductivity than the case 28 and the holder 12.

[0039] FIG. 7 is a plan view showing the pressure chamber forming plate 25. In FIG. 7, a view of the pressure chamber forming plate 25 seen in the Z1 direction is shown. As shown in FIGS. 2 and 7, a plurality of pressure chambers 57A and 57B are formed in the pressure chamber forming plate 25. The pressure chambers 57A and 57B are spaced apart in the X-axis direction. The pressure chambers 57A and 57B are respectively provided for the plurality of nozzles N. The plurality of pressure chambers 57A are partitioned by a plurality of partition walls 59A extending in the X-axis direction and the Z-axis direction and are arranged at a predetermined interval in the Y-axis direction. The plurality of pressure chambers 57B are partitioned by a plurality of partition walls 59B extending in the X-axis direction and the Z-axis direction and are arranged at a predetermined interval in the Y-axis direction.

[0040] The pressure chamber 57A extends in the X-axis direction and communicates with the relay flow path 55A and the communication flow path 58A. The pressure chamber 57B extends in the X-axis direction and communicates with the relay flow path 55B and the communication flow path 58B. The pressure chamber forming plate 25 can be manufactured from, for example, a single crystal silicon substrate. The pressure chamber forming plate 25 may be manufactured from other materials such as metal or ceramics, but when the case 28 and the holder 12 are formed of resin, it is preferably a material having a higher thermal conductivity than the case 28 and the holder 12.

[0041] FIG. 8 is a plan view showing the diaphragm 26. In FIG. 8, a view of the diaphragm 26 seen in the Z1 direction is shown. FIG. 9 is a cross-sectional view showing the diaphragm 26 and the piezoelectric actuator 30. The diaphragm 26 shown in FIGS. 8 and 9 is disposed on the upper surface of the pressure chamber forming plate 25. The thickness direction of the diaphragm 26 is along the Z-axis direction. The diaphragm 26 covers the opening of the pressure chamber forming plate 25. Among the diaphragm 26, the portion covering the opening of the pressure chamber forming plate 25 constitutes the upper wall surface of the pressure chamber 57. The diaphragm 26 is formed from a plurality of insulating layers 26a, 26b. The diaphragm 26 includes an insulating layer 26a made of silicon dioxide (SiO2) and an insulating layer 26b made of zirconium dioxide (ZrO2). The insulating layer 26a is formed on the pressure chamber forming plate 25, and the insulating layer 26b is formed on the insulating layer 26a. Note that the diaphragm 26 or a part of the diaphragm 26 and the pressure chamber forming plate 25 may be integrally formed. For example, when the pressure chamber forming plate 25 is formed of silicon, a recess as the pressure chamber 57 may be formed by etching one surface of a single crystal substrate of silicon, and an insulating layer 26a made of silicon dioxide (SiO2) may be formed by oxidizing the bottom surface of the recess.

[0042] The diaphragm 26 is driven by the piezoelectric actuator 30 and vibrates in the Z-axis direction. The total thickness of the diaphragm 26 is, for example, 2 μm or less. The total thickness of the diaphragm 26 may be 15 μm or less, 40 μm or less, or 100 μm or less. For example, when the total thickness of the diaphragm 26 is 15 μm or less, it may include a resin layer. The diaphragm 26 may be formed of metal. Examples of the metal include stainless steel and nickel. When the diaphragm 26 is made of metal, the plate thickness of the diaphragm 26 may be 15 μm or more and 1000 μm or less.

[0043] The plurality of piezoelectric actuators 30 are arranged on the portions of the diaphragm 26 that constitute the Z2-direction wall surfaces of the plurality of pressure chambers 57A and on the portions of the diaphragm 26 that constitute the Z2-direction wall surfaces of the plurality of pressure chambers 57B. The plurality of piezoelectric actuators 30 are provided corresponding to the plurality of pressure chambers 57A and 57B, respectively. The piezoelectric actuator 30 includes a first electrode 31, a piezoelectric layer 33, and a second electrode 32. These first electrode 31, piezoelectric layer 33, and second electrode 32 are laminated in this order on the diaphragm 26. The first electrode 31 is an individual electrode, and the second electrode 32 is a common electrode. Note that the first electrode 31 may be configured as a common electrode, and the second electrode 32 may be configured as an individual electrode.

[0044] The plurality of first electrodes 31 are arranged at a predetermined interval in the Y-axis direction. The plurality of first electrodes 31 are respectively arranged at positions overlapping the plurality of pressure chambers 57A and 57B when viewed in the Z-axis direction. The first electrode 31 has a predetermined length in the X-axis direction and is drawn inward from the position on the pressure chambers 57A and 57B toward the center line O. Note that the center line O is shown in FIGS. 2 and 4.

[0045] The first electrode 31 is formed of, for example, an electrode layer containing a low-resistance conductive material such as platinum (Pt) or iridium (Ir), and an underlayer containing titanium (Ti). The electrode layer may be formed of an oxide such as strontium ruthenate (SrRuO3) and lanthanum nickelate (LaNiO3), for example.

[0046] The piezoelectric layer 33 is laminated on the first electrode 31. The piezoelectric layer 33 is arranged so as to cover the plurality of first electrodes 31. The piezoelectric layer 33 is a strip-shaped dielectric film extending in the Y-axis direction.

[0047] The second electrode 32 is laminated on the piezoelectric layer 33. The second electrode 32 extends in the Y-axis direction so as to cover the plurality of first electrodes 31 with the piezoelectric layer 33 interposed therebetween. The second electrode 32 is formed of, for example, an electrode layer containing a low-resistance conductive material such as Pt or Ir and an underlying layer containing Ti. The electrode layer may be formed of an oxide such as SrRuO3 and LaNiO3, for example.

[0048] Among the piezoelectric layer 33, the region sandwiched between the first electrode 31 and the second electrode 32 in the Z-axis direction becomes the drive region. This drive region overlaps with the pressure chambers 57A and 57B when viewed in the Z-axis direction.

[0049] A lead electrode 34 is electrically connected to the piezoelectric actuator 30. The plurality of lead electrodes 34 are respectively provided for the plurality of first electrodes 31. The lead electrode 34 extends in the X-axis direction and is drawn out to the inside of the opening 74 of the protective substrate 27. The opening 74 is shown in FIGS. 2 and 4, but the illustration of the lead electrode 34 is omitted in FIGS. 2 and 4. The opening 74 penetrates the protective substrate 27 in the Z-axis direction. The lead electrode 34 is electrically connected to the COF 40 inside the opening 74.

[0050] The lead electrode 34 is formed of a conductive material having a lower resistance than the first electrode 31. For example, the lead electrode 34 is a conductive pattern having a structure in which a conductive film of gold (Au) is laminated on the surface of a conductive film formed of nichrome (NiCr).

[0051] FIG. 10 is a plan view showing the protective substrate 27. FIG. 10 shows the protective substrate 27 in a state of being disposed on the pressure chamber forming plate 25. In FIG. 10, a plurality of piezoelectric actuators 30 are indicated by phantom lines.

[0052] As shown in FIGS. 4 and 10, the protective substrate 27 is arranged to cover a plurality of piezoelectric actuators 30 from the Z2 direction. The protective substrate 27 is rectangular when viewed in the Z-axis direction. The protective substrate 27 protects a plurality of piezoelectric actuators 30 and reinforces the mechanical strength of the pressure chamber forming plate 25 and the diaphragm 26. The protective substrate 27 is a member in which a flow path 51 through which liquid flows is not formed. The protective substrate 27 is formed of metal or ceramics. Examples of the metal include stainless steel, aluminum, and copper. Examples of the ceramics include silicon dioxide (SiO2), silicon carbide (SiC), aluminum nitride (AlN), sapphire (AL2O3), alumina (AL2O3), silicon nitride (Si3N4), cermet, and yttria (Y2O3). For example, the protective substrate 27 preferably has a thermal conductivity of 1.0 W / m·K or more at room temperature (20° C.), and more preferably has a thermal conductivity of 10.0 W / m·K or more at room temperature (20° C.). In the present embodiment, the protective substrate 27 is formed of silicon dioxide (SiO2).

[0053] The protective substrate 27 includes a plate portion 27a and leg portions 27b. The plate portion 27a is arranged to cover a plurality of piezoelectric actuators 30 in the Z-axis direction. The plate portion 27a is rectangular when viewed in the Z-axis direction. Also, the plate portion 27a coincides with the outer shape of the protective substrate 27 when viewed in the Z1 direction. The leg portions 27b are formed so as to surround the plate portion 27a when viewed in the Z-axis direction. The leg portions 27b project in the Z1 direction more than the plate portion 27a. The leg portions 27b are arranged on both sides in the X-axis direction and both sides in the Y-axis direction with respect to a group of a plurality of piezoelectric actuators 30 arranged side by side in the Y-axis direction. The leg portions 27b are joined to the diaphragm 26. As shown in FIG. 9, at the position where the lead electrode 34 is arranged, the lead electrode 34 exists between the leg portion 27b and the diaphragm 26. The protective substrate 27 is adhered to the diaphragm 26 by, for example, an adhesive.

[0054] The protective substrate 27 is formed with recesses 27c for accommodating a plurality of piezoelectric actuators 30. The recess 27c is a space in the Z1 direction of a portion where the leg portion 27b of the plate portion 27a is not provided, and is a space surrounded by the leg portion 27b. The recess 27c is formed to be recessed in the Z2 direction from the surface of the protective substrate 27 in the Z1 direction.

[0055] As shown in FIG. 10, an opening 74 is formed in the central portion of the protective substrate 27 in the X-axis direction. The opening 74 penetrates the protective substrate 27 in the Z-axis direction. The opening 74 is elongated in the Y-axis direction. The length of the opening 74 in the Y-axis direction corresponds to the length of the nozzle row N1.

[0056] As shown in FIG. 2, the holder 12 is provided with an opening 75 penetrating in the Z-axis direction. The opening 75 is elongated in the Y-axis direction. The length of the opening 75 in the Y-axis direction corresponds to the length of the nozzle row N1. The width of the opening 75 in the X-axis direction is substantially the same as the width of the opening 73 of the case 28.

[0057] The circuit board 13 is provided with an opening 76 penetrating in the Z-axis direction. The opening 76 is elongated in the Y-axis direction. The length of the opening 76 in the Y-axis direction corresponds to the length of the nozzle row N1. The width of the opening 76 in the X-axis direction is narrower than the width of the opening 75 of the holder 12 in the X-axis direction.

[0058] The COF 40 includes a flexible wiring board 41 and a drive circuit 42. The flexible wiring board 41 is a wiring board having flexibility. The flexible wiring board 41 is, for example, an FPC (Flexible Printed Circuit). The flexible wiring board 41 may also be an FFC (Flexible Flat Cable), for example.

[0059] The flexible wiring board 41 is inserted into the opening 76 from the Z2 direction of the circuit board 13 and extends in the Z-axis direction. The flexible wiring board 41 passes through the opening 75 of the holder 12 and the opening 73 of the case 28 and is inserted into the opening 74 of the protective substrate 27.

[0060] The end portion of the flexible printed circuit board 41 in the Z2 direction is electrically connected to the circuit board 13. The connection terminal 41c, which is the end portion of the flexible printed circuit board 41 in the Z1 direction, is electrically connected to the lead electrode 34 within the opening 74. The end portion of the flexible printed circuit board 41 in the Z1 direction may be joined to the diaphragm 26 in a portion where the lead electrode 34 is not disposed.

[0061] The thickness direction of the flexible printed circuit board 41 follows, for example, the X-axis direction. The thickness direction of the flexible printed circuit board 41 may be inclined with respect to the X-axis. The flexible printed circuit board 41 has a predetermined length in the Y-axis direction. The length of the flexible printed circuit board 41 in the Y-axis direction corresponds, for example, to the length of the nozzle row N1 in the Y-axis direction.

[0062] Among the flexible printed circuit board 41, a wiring portion is provided on one surface 41a. The surface 41a is, for example, a surface in the X2 direction. Among the flexible printed circuit board 41, no wiring portion is provided on the other surface 41b. The surface 41b is, for example, a surface in the X1 direction. The surface 41b is the surface on the opposite side of the surface 41a where the drive circuit 42 is provided.

[0063] The drive circuit 42 is mounted on the flexible printed circuit board 41. The drive circuit 42 is provided on the surface 41a of the flexible printed circuit board 41. The drive circuit 42 is disposed, for example, within the opening 75 of the holder 12. A part of the drive circuit 42 may be disposed within the opening 73 of the case 28.

[0064] The drive circuit 42 includes a switching element for driving the piezoelectric actuator 30. The drive circuit 42 is electrically connected to the control unit 3 via the flexible wiring board 41 and the circuit board 13. The drive circuit 42 receives the drive signal output from the control unit 3. The switching element switches whether to supply the drive signal generated by the control unit 3 to the piezoelectric actuator 30. The drive circuit 42 supplies a drive voltage or current to the piezoelectric actuator 30 in response to a command signal, causing the diaphragm 26 to vibrate.

[0065] The liquid ejection head 10 includes a heat dissipation member 81 that conducts the heat of the drive circuit 42. The heat dissipation member 81 is, for example, plate-shaped. The thickness direction of the heat dissipation member 81 is along the X-axis direction. The thickness direction of the heat dissipation member 81 may be inclined with respect to the X-axis direction. The heat dissipation member 81 is long in the Y-axis direction. The length of the heat dissipation member 81 in the Y-axis direction corresponds to the length of the nozzle row N1 in the Y-axis direction. The length of the heat dissipation member 81 in the Y-axis direction may be substantially the same as the length of the drive circuit 42 in the Y-axis direction. The heat dissipation member 81 may be composed of a plurality of plate materials.

[0066] The heat dissipation member 81 is disposed inside the opening 75 of the holder 12 and the opening 73 of the case 28. The heat dissipation member 81 is disposed in the X1 direction of the flexible wiring board 41. The surface 81a of the heat dissipation member 81 is in contact with the surface 41b of the flexible wiring board 41. The surface 81a of the heat dissipation member 81 is the surface in the X2 direction and is the surface closer to the flexible wiring board 41. The heat dissipation member 81 may be adhered to the flexible wiring board 41 using, for example, an adhesive. The heat dissipation member 81 may be adhered to the flexible wiring board 41 using, for example, a tape, a film, or the like. The heat dissipation member 81 only needs to be able to transfer the heat of the drive circuit 42 and may be joined to the flexible wiring board 41 by other methods.

[0067] The heat radiating member 81 is in contact with the protective substrate 27. The end portion 81b of the heat radiating member 81 in the Z1 direction is in contact with the portion of the protective substrate 27 closer to the pressure chamber 57A. As shown in FIG. 10, the heat radiating member 81 is in contact with the portion of the protective substrate 27 arranged in the X1 direction with respect to the opening 74. More specifically, the heat radiating member 81 is in contact with the portion between the opening 74 and the recess 27c arranged in the X1 direction with respect to the opening 74 in the plate portion 27a. A part of the heat radiating member 81 is arranged so as to overlap the protective substrate 27 when viewed in the Z1 direction. The heat radiating member 81 may be adhered to the protective substrate 27 using, for example, an adhesive. The heat radiating member 81 only needs to be able to transfer heat to the protective substrate 27, and may be joined to the protective substrate 27 by other methods. The heat radiating member 81 may only be in contact with the protective substrate 27.

[0068] Examples of the material of the heat radiating member 81 include metal or ceramics. Examples of metals include stainless steel, aluminum, and copper. Examples of ceramics include silicon dioxide (SiO2), silicon carbide (SiC), aluminum nitride (AlN), sapphire (AL2O3), alumina (AL2O3), silicon nitride (Si3N4), cermet, and yttria (Y2O3). The material of the heat radiating member 81 only needs to be able to conduct heat, and other materials may also be used. For example, the heat radiating member 81 preferably has a thermal conductivity of 1.0 W / m·K or more at room temperature (20°C), and more preferably has a thermal conductivity of 10.0 W / m·K or more at room temperature (20°C). In the present embodiment, the heat radiating member 81 is made of stainless steel.

[0069] As shown in FIG. 4, the width W1 along the X-axis direction of the end portion 81b of the heat radiating member 81 may be larger than the width W2 along the X-axis direction of the opening 74 of the protective substrate 27. The end portion 81b is the end portion closer to the diaphragm 26 in the Z-axis direction. Further, the end portion 81b and the connection terminal 41c are separated in the Z-axis direction. A gap is formed between the end portion 81b and the connection terminal 41c in the Z-axis direction, and they are not in contact.

[0070] Next, the ink flow in the liquid ejection head 10 will be described. FIG. 11 is a schematic diagram showing the ink flow path 91 in the holder 12. Inside the holder 12, an ink flow path 91 is formed.

[0071] The flow path 91 of the holder 12 includes a supply port 92, a branch flow path 93, a converging flow path 94, and a discharge port 95. The holder 12 includes a plurality of flow path members. Grooves and openings are formed in the flow path members. These grooves and openings form the flow path 91 inside the holder 12.

[0072] The branch flow path 93 is communicated with the supply port 92 of the holder 12. The branch flow path 93 is respectively communicated with the supply ports 52A of the plurality of head chips 11. The converging flow path 94 is communicated with the discharge ports 52B of the plurality of head chips 11. The converging flow path 94 is communicated with the discharge port 95 of the holder 12.

[0073] The ink supplied from the circulation mechanism 5 flows into the inside of the holder 12 through the supply port 92 of the holder 12. The ink flowing into the holder 12 flows through the branch flow path 93, is distributed to the plurality of head chips 11, and flows into the head chips 11 through the supply ports 52A.

[0074] A part of the ink flowing into the head chip 11 is ejected from the nozzle N. The ink not ejected from the nozzle N is discharged to the outside of the head chip 11 from the discharge port 52B. The ink discharged from the discharge ports 52B of the plurality of head chips 11 flows through the converging flow path 94, merges, and is discharged from the discharge port 95 of the holder 12. The ink discharged from the discharge port 95 of the holder 12 is circulated by the circulation mechanism 5 and flows into the supply port 92 of the holder 12 again. Thus, the ink is circulated via the circulation mechanism 5.

[0075] As shown in FIGS. 2 and 3, the ink supplied to the head chip 11 is supplied into the common liquid chambers 53A and 54A through the supply port 52A. The ink inside the common liquid chambers 53A and 54A flows into each of the plurality of relay flow paths 55A. The ink inside the common liquid chambers 53A and 54A is respectively distributed to the plurality of pressure chambers 57A.

[0076] The ink inside the pressure chamber 57A passes through the communication flow path 58A and is supplied into the communication flow path 58C. A part of the ink inside the communication flow path 58C is ejected from the nozzle N.

[0077] In the head chip 11, there are cases where the ink is circulated via the communication flow path 58C, cases where the piezoelectric actuator 30 is driven, ink is discharged from the pressure chambers 57A and 57B, and ink is ejected from the nozzle N, and cases where the ink is circulated without passing through the communication flow path 58C.

[0078] When the ink is circulated via the communication flow path 58C, the ink inside the communication flow path 58C passes through the communication flow path 58B and flows into the pressure chamber 57B. The ink inside the pressure chamber 57B passes through the relay flow path 55B and is discharged into the common liquid chambers 53B and 54B. The ink inside the common liquid chambers 53B and 54B passes through the discharge port 52B and is discharged outside the head chip 11. The ink discharged from the head chip 11 is circulated via the circulation mechanism 5 as described above.

[0079] When the piezoelectric actuator 30 is driven, the diaphragm 26 vibrates, the volume inside the pressure chambers 57A and 57B changes, and the pressure of the ink rises. The ink inside the pressure chamber 57A passes through the communication flow paths 58A and 58C and is ejected from the nozzle N. The ink inside the pressure chamber 57B passes through the communication flow paths 58B and 58C and is ejected from the nozzle N.

[0080] As shown in FIG. 3, a bypass channel 96 is connected to a channel 51 inside the head chip 11. One end 96a of the bypass channel 96 is connected to the common liquid chambers 53A and 54A. The other end 96b of the bypass channel 96 is connected to the common liquid chambers 53B and 54B. When viewed in the Z-axis direction, the bypass channel 96 includes a channel passing through the Y1 direction of the nozzle row N1 and a channel passing through the Y2 direction of the nozzle row N1.

[0081] A part of the ink inside the common liquid chambers 53A and 54A flows through the inside of the bypass channel 96 and flows into the inside of the common liquid chambers 53B and 54B. The ink inside the common liquid chambers 53B and 54B can be circulated through the circulation mechanism 5 as described above.

[0082] The flow resistance of the bypass channel 96 is lower than the flow resistance of the circulation channel via the communication channel 58C. Therefore, the ink inside the common liquid chambers 53A and 54A easily flows into the bypass channel 96.

[0083] Among the ink channels 51 of the head chip 11, the channels passing through the relay channel 55A, the pressure chamber 57A, and the communication channels 58A and 58C and communicating with the nozzle N are included in the individual supply channel 51A. Among the channels 51, the channels passing through the communication channel 58C, the communication channel 58B, the pressure chamber 57B, and the relay channel 55B are included in the individual recovery channel 51B.

[0084] Next, with reference to FIGS. 2 and 4, the heat transfer path of the heat generated from the drive circuit 42 will be described. A part of the heat generated in the drive circuit 42 is conducted to the heat dissipation member 81 through the flexible wiring board 41. The heat conducted to the heat dissipation member 81 is thermally conducted by the heat dissipation member 81 and conducted to the protective substrate 27.

[0085] The heat conducted to the protective substrate 27 is dispersed through the legs 27b of the protective substrate 27 and conducted to the diaphragm 26. The diaphragm 26 defines the Z2-direction wall surfaces of the pressure chambers 57A and 57B and is in contact with the ink inside the pressure chambers 57A and 57B.

[0086] The heat conducted to the diaphragm 26 is transferred to the ink in the pressure chambers 57A and 57B. When the ink in the pressure chambers 57A and 57B is ejected from the nozzles N, the heat transferred from the diaphragm 26 is discharged to the outside of the liquid ejection head 10 together with the ink. Thereby, the heat generated from the drive circuit 42 is radiated to the outside of the liquid ejection head 10.

[0087] Also, even when the ink is not being ejected, since the ink is circulating, the heat transferred from the diaphragm 26 can be dispersed along with the flow of the ink.

[0088] According to such a liquid ejection head 10, the heat generated in the drive circuit 42 is conducted to the protective substrate 27 and the diaphragm 26 via the heat radiating member 81 and transferred to the ink. Since the ink is ejected from the nozzles N, the heat can be discharged to the outside of the liquid ejection head 10 together with the ink. Thereby, the heat generated from the drive circuit 42 can be discharged to the outside of the liquid ejection head 10. As a result, the temperature rise in the drive circuit 42 can be suppressed. By cooling the drive circuit 42, the performance of the drive circuit 42 can be maintained and the ink can be preferably ejected by the liquid ejection head 10.

[0089] In the liquid ejection head 10, since a plurality of pressure chambers 57A and 57B are provided, the heat conducted to the diaphragm 26 can be transferred to the ink via the plurality of partition walls 59A and 59B that form the walls of the plurality of pressure chambers 57A and 57B. The total area of the diaphragm 26 that forms the walls of the plurality of pressure chambers 57A and 57B is, for example, larger than the total area of the walls of the common liquid chambers 53A, 53B, 54A, and 54B that contact the ink. Therefore, by transferring the heat to the ink via the walls of the pressure chambers 57A and 57B, the heat of the drive circuit 42 can be efficiently radiated. In particular, when the number of nozzles N provided in the nozzle row N1 of the head chip 11 is, for example, 300 or more, a plurality of pressure chambers 57A and 57B are provided corresponding to 300 or more nozzles N in the head chip 11, and the total area of the walls of the plurality of pressure chambers 57A and 57B increases, and the effect becomes more remarkable.

[0090] Also, the thickness of the diaphragm 26 is thinner compared to other members. For example, the thickness of the diaphragm 26 is thinner compared to the pressure chamber forming plate 25 adjacent in the Z1 direction. Therefore, the heat transfer effect is not hindered by the diaphragm 26.

[0091] In the liquid ejection head 10, since the end portion 81b of the heat dissipation member 81 is connected to the protection substrate 27, the heat conducted by the heat dissipation member 81 is conducted to the protection substrate 27. On the protection substrate 27, leg portions 27b are formed so as to surround the recessed portion 27c. Since this leg portion 27b is connected to the diaphragm 26, the heat conducted to the protection substrate 27 is dispersed by the leg portion 27b and conducted to the diaphragm 26. The leg portions 27b are arranged so as to surround the plurality of pressure chambers 57A and 57B when viewed in the Z-axis direction. Therefore, heat can be efficiently transferred to the portions around the pressure chambers 57A and 57B of the diaphragm 26 through the leg portions 27b. The heat conducted to the diaphragm 26 is transferred to the ink through the wall surfaces of the plurality of pressure chambers 57A and 57B. As a result, the heat of the drive circuit 42 is efficiently dissipated.

[0092] In the liquid ejection head 10, the case 28 and the holder 12 are made of resin, and the drive circuit 42 is provided inside the opening 75 of the holder 12. Therefore, the weight of the liquid ejection head 10 can be reduced compared to a liquid ejection head provided with a metal case and holder. Further, when the case 28 and the holder 12 are made of resin, it can be manufactured at a lower cost compared to a configuration provided with a metal case and holder. Since the holder 12 holds the plurality of head chips 11, it is likely to be enlarged. Therefore, when the holder 12 is made of resin, the merits of weight reduction and cost reduction are great compared to a metal holder.

[0093] In the liquid ejection head 10, an individual supply channel 51A and an individual recovery channel 51B are provided, and the ink flowing through the channel 51 inside the head chip 11 can be circulated. Since ink flow occurs inside the channel 51, it is possible to prevent the ink with an increased temperature from staying inside the channel 51 as it is. The heat-transferred ink is discharged outside the head chip 11, and the heat is dissipated. As a result, even when the ink is not being ejected, heat can be transferred to the ink via the diaphragm 26, and the heat of the drive circuit 42 can be efficiently radiated.

[0094] In the liquid ejection head 10, since a bypass channel 96 is provided, the circulation amount of the ink can be increased. The flow rate of the ink flowing through the common liquid chambers 54A and 54B formed by the communication plate 24 can be increased, and the amount of heat transfer of the heat transmitted from the drive circuit 42 to the ink flowing through the common liquid chambers 54A and 54B via the heat dissipation member 81, the diaphragm 26, the pressure chamber forming plate 25, and the communication plate 24 can be increased.

[0095] In the liquid ejection head 10, the heat dissipation member 81 is arranged in the X1 direction of the flexible wiring board 41 and at a position close to the pressure chamber 57A, and the end portion 81b is connected to the protective substrate 27. Therefore, the heat transfer path can be shortened, and heat can be transferred to the ink inside the pressure chamber 57A. Since the ink inside the pressure chamber 57A is ejected from the nozzle N, the heat is immediately discharged together with the ink. Since the ink is supplied to the pressure chamber 57A from the common liquid chambers 53A and 54A, the flow rate of the ink is ensured. When the ejection amount of the ink from the pressure chamber 57A increases, accordingly, the flow rate of the ink flowing into the pressure chamber 57A from the common liquid chambers 53A and 54A also increases, so that heat can be efficiently radiated.

[0096] When the ink in the pressure chamber 57B is ejected, the ink flows from the common liquid chambers 53B and 54B into the pressure chamber 57B. Even if the ink in the common liquid chambers 53B and 54B decreases, the ink is not supplied through the discharge port 52B. When the ejection amount of the ink from the pressure chamber 57B increases, the flow rate of the ink supplied from the common liquid chambers 53B and 54B to the pressure chamber 57B is smaller compared to the flow rate of the ink supplied from the common liquid chambers 53A and 54A to the pressure chamber 57A. Therefore, it is more efficient to dissipate heat if the amount of heat transferred to the ink in the pressure chamber 57A is greater than the amount of heat transferred to the ink in the pressure chamber 57B. In other words, the end portion 81b of the heat dissipation member 81 can dissipate heat more efficiently when it is connected to a position closer to the pressure chamber 57A than to a position closer to the pressure chamber 57B.

[0097] Also, when the pressure chamber forming plate 25 and the communication plate 24 are made of metal, part of the heat transmitted to the diaphragm 26 is conducted to the pressure chamber forming plate 25 and the communication plate 24. Thereby, it can be transmitted to the ink through the pressure chamber forming plate 25 and the communication plate 24. For example, the heat of the drive circuit 42 can also be transferred to the ink from the relay flow paths 55A and 55B and the wall surfaces of the common liquid chambers 54A and 54B. As a result, the heat transfer area is increased, and the heat of the drive circuit 42 can be dissipated efficiently.

[0098] According to such a liquid ejection head 10, since the drive circuit 42 can be dissipated efficiently, it is possible to prevent the drive circuit 42 from becoming high temperature and avoid damage to the drive circuit. Since the temperature rise of the drive circuit 42 can be suppressed, there is no need to limit the performance of the drive circuit 42.

[0099] For example, when the number of nozzles N in the head chip 11 is increased, the number of switching times in the drive circuit 42 increases, and the amount of heat generated in the drive circuit 42 tends to increase. In the liquid ejection head 10, since the heat dissipation performance is improved and the temperature rise in the drive circuit 42 can be suppressed, it is possible to increase the installation numbers of the nozzles N and the piezoelectric actuators 30 in the head chip 11 to achieve high density.

[0100] For example, if the thickness of the piezoelectric layer 33 is reduced to thin the piezoelectric actuator 30, the capacitance in the piezoelectric layer 33 increases. To ensure the displacement amount of the diaphragm 26 using the thinned piezoelectric layer 33, the current supplied to the piezoelectric layer 33 tends to increase. In the liquid ejection head 10, since the heat dissipation performance is improved and the temperature rise in the drive circuit 42 can be suppressed, the piezoelectric layer 33 can be thinned to thin the piezoelectric actuator 30. Thereby, the head chip 11 can be miniaturized.

[0101] For example, if the number of ink ejection times per unit time is increased, the switching frequency and current in the drive circuit 42 increase, and the amount of heat generation in the drive circuit 42 tends to increase. In the liquid ejection head 10, since the heat dissipation performance is improved and the temperature rise in the drive circuit 42 can be suppressed, the high-speed ink ejection in the head chip 11 can be achieved.

[0102] In the present embodiment, the pressure chamber 57A and the pressure chamber 57B are provided for one nozzle N, but a configuration in which only one of the pressure chamber 57A and the pressure chamber 57B is provided may be used.

[0103] Next, with reference to FIG. 12, the liquid ejection head 10B according to the second embodiment will be described. FIG. 12 is a cross-sectional view showing the liquid ejection head 10B according to the second embodiment. In the description of the second embodiment, the same description as that of the first embodiment described above will be omitted. The liquid ejection head 10B includes a nozzle plate 121, a flow path member 124, a diaphragm 126, a common liquid chamber forming member 127, a case 128, a piezoelectric actuator 130, an FPC (Flexible Printed Circuit) 141, a drive circuit 142, a circuit board 143, and a heat dissipation member 181.

[0104] The liquid ejection head 10B is configured to be line-symmetric with respect to a center line O that passes through the center in the X-axis direction and extends in the Z-axis direction. In the liquid ejection head 10B, a nozzle plate 121, a flow path member 124, a diaphragm 126, and a common liquid chamber forming member 127 are arranged in this order from the bottom. The common liquid chamber forming member 127 may be composed of, for example, a plurality of members.

[0105] A plurality of nozzles N are formed in the nozzle plate 121. The nozzles N are arranged in the Y-axis direction to form a nozzle row N1. Inside the liquid ejection head 10B, there are common liquid chambers 152, 153, individual supply flow paths 154, pressure chambers 155, communication holes 156, individual recovery flow paths 157, and a common liquid chamber 158 as flow paths through which ink flows.

[0106] Common liquid chambers 152, 153, 158 are formed in the common liquid chamber forming member 127. The common liquid chamber forming member 127 is formed of, for example, stainless steel. The common liquid chamber forming member may be formed of other metals such as aluminum and copper. Also, the common liquid chamber forming member 127 may be composed of resin.

[0107] The common liquid chambers 152, 153 communicate with each other in the Z-axis direction. The common liquid chambers 152, 153 are included in a supply-side flow path that supplies ink to the pressure chamber 155. A common liquid chamber 158 is arranged outside the common liquid chamber 153 in the X-axis direction. Note that "outside" means farther from the center line O, and "inside" means closer to the center line O. The common liquid chamber 158 is included in a recovery-side flow path that recovers the ink that has not been ejected from the nozzles N among the ink discharged from the pressure chamber 155. A space is formed at the central portion of the common liquid chamber forming member 127 in the X-axis direction, in which a piezoelectric actuator 130, an FPC 141, and a heat dissipation member 81 are arranged. Details will be described later.

[0108] The diaphragm 126 has a vibration portion 126a and filter portions 126b, 126c. The vibration portion 126a constitutes the wall surface of the pressure chamber 155 in the Z2 direction. The filter portions 126b, 126c are arranged outside the vibration portion 126a in the X-axis direction.

[0109] The diaphragm 126 is formed of, for example, nickel (Ni). The diaphragm 126 may be formed of a nickel alloy containing nickel. The diaphragm 126 may be formed of other metals. The thickness of the diaphragm 126 may be, for example, 40 μm or less. Also, a plurality of diaphragms 126 may be laminated in the Z-axis direction. The total thickness of the diaphragms 126 may be 100 μm or less.

[0110] The filter portion 126b is disposed in the Z1 direction of the common liquid chamber 153. The ink inside the common liquid chamber 153 passes through the filter portion 126b and flows into the individual supply flow path 154. The surface of the filter portion 126b in the Z2 direction constitutes a part of the wall surface of the common liquid chamber 153 in the Z1 direction. The surface of the filter portion 126b in the Z1 direction constitutes a part of the wall surface of the individual supply flow path 154 in the Z2 direction.

[0111] The filter portion 126c is disposed in the Z1 direction of the common liquid chamber 158. The ink inside the individual recovery flow path 157 passes through the filter portion 126c and flows into the common liquid chamber 158. The surface of the filter portion 126c in the Z2 direction constitutes a part of the wall surface of the common liquid chamber 158 in the Z1 direction. The surface of the filter portion 126c in the Z1 direction constitutes a part of the wall surface of the individual recovery flow path 157 in the Z2 direction. Also, the diaphragm 126 may include a portion that functions as a compliance substrate. Thereby, heat can be transferred from the portion that functions as a compliance substrate to the ink.

[0112] In the flow path member 124, an individual supply flow path 154, a pressure chamber 155, a communication hole 156, and an individual recovery flow path 157 are formed. The individual supply flow path 154 communicates with the common liquid chamber 153 via the filter portion 126b. The individual supply flow path 154 extends in the X-axis direction and communicates with the pressure chamber 155.

[0113] The flow path member 124 is formed of, for example, stainless steel. The flow path member 124 may be formed of other metals such as aluminum and copper. Further, the flow path member 124 may be made of resin. Further, the flow path member 124 may be configured by laminating a plurality of plate-like members in the Z-axis direction.

[0114] A partition wall 124a is provided at the center of the flow path member 124 in the X-axis direction. The thickness direction of the partition wall 124a is along the X-axis direction. Pressure chambers 155 are arranged on both sides in the X-axis direction with the partition wall 124a interposed therebetween. The partition wall 124a constitutes a part of the wall surface of the pressure chamber 155.

[0115] A partition wall 124b is provided in the Z1 direction of the individual supply flow path 154 and the pressure chamber 155. The thickness direction of the partition wall 124b is along the Z-axis direction. An individual recovery flow path 157 is formed in the Z1 direction of the partition wall 124b. The surface of the partition wall 124b in the Z2 direction constitutes the wall surface of the individual supply flow path 154 in the Z1 direction and the wall surface of the pressure chamber 155 in the Z1 direction. The surface of the partition wall 124b in the Z1 direction constitutes the wall surface of the individual recovery flow path 157 in the Z2 direction.

[0116] The communication hole 156 penetrates the partition wall 124b in the Z-axis direction in the vicinity of the partition wall 124a. The communication hole 156 communicates the pressure chamber 155 and the individual recovery flow path 157. The ink inside the pressure chamber 155 flows into the individual recovery flow path 157 through the communication hole 156.

[0117] The individual recovery flow path 157 extends outward from the central portion in the X-axis direction. In the X-axis direction, the end farther from the center line O of the individual recovery flow path 157 extends in the Z2 direction and communicates with the common liquid chamber 158 through the filter portion 126c.

[0118] The nozzle N is in the vicinity of the partition wall 124a and is arranged at the position in the Z1 direction of the communication hole 156. The ink that has passed through the communication hole 156 flows in the Z1 direction through the individual recovery flow path 157 and is ejected from the nozzle N. The ink that has not been ejected from the nozzle N flows through the individual recovery flow path 157, passes through the filter portion 126c, and flows into the common liquid chamber 158.

[0119] The piezoelectric actuator 130 is at the central portion in the X-axis direction of the common liquid chamber forming member 127 and is arranged in the Z2 direction of the pressure chamber 155. A diaphragm 126 is arranged between the piezoelectric actuator 130 and the pressure chamber 155. An opening 171 penetrating in the Z-axis direction is formed in the common liquid chamber forming member 127.

[0120] The opening 171 is arranged between the piezoelectric actuator 130 and the common liquid chambers 152, 153, 158 in the X-axis direction. The case 128 is formed of, for example, resin. A recess 128a that is recessed in the Z2 direction from the surface in the Z1 direction is formed in the case 128. An opening 128b penetrating in the Z-axis direction is formed at the central portion of the case 128 in the X-axis direction. The opening 171 of the common liquid chamber forming member 127, the recess 128a of the case 128, and the opening 128b communicate with each other.

[0121] The FPC 141 and the heat dissipation member 181 extend in the Z-axis direction within the opening 171 and the recess 128a. The drive circuit 142 is arranged in the recess 128a. The portion of the FPC 141 in the Z1 direction is inserted into the opening 171 and is electrically connected to the piezoelectric actuator 130. The thickness direction of the FPC 141 is along the X-axis direction. The length of the FPC 141 in the Y-axis direction corresponds to the length of the nozzle row N1 in the Y-axis direction.

[0122] The FPC 141 is electrically connected to the circuit board 143. The circuit board 143 is arranged inside the opening 128b of the case 128. The thickness direction of the circuit board 143 is along the X-axis direction. The end portion of the circuit board 143 in the Z1 direction projects into the recess 128a. The end portion of the circuit board 143 in the Z2 direction projects outside the case 128.

[0123] On the surface 141a of the FPC 141, a drive circuit 142 is mounted. The surface 141a is, for example, the surface closer to the center line O. On the surface 141b of the FPC 141 opposite to the surface 141a, a heat dissipation member 181 is provided. The heat dissipation member 181 has a plate shape. The plate thickness direction of the heat dissipation member 181 is along the X-axis direction.

[0124] The heat dissipation member 181 is in contact with the surface 141b of the FPC 141. The heat dissipation member 181 has a main body portion 181a that contacts the FPC 141 and an end portion 181b that extends in the Z1 direction from the main body portion 181a. The surface 181c of the main body portion 181a is in contact with the surface 141b of the FPC 141. The end portion 181b in the Z1 direction is in contact with the diaphragm 126. The plate thickness of the end portion 181b is thinner than the plate thickness of the main body portion 181a. In the X-axis direction, a gap is formed between the end portion 181b and the FPC 141 and they are not in contact. In the Z1 direction of the diaphragm 126, an individual supply flow path 154 is arranged. The position where the end portion 181b contacts is closer to the individual supply flow path 154 than the individual recovery flow path 157.

[0125] In such a liquid ejection head 10B, a drive signal is output from the drive circuit 142 to drive the piezoelectric actuator 130. Thereby, the vibration portion 126a of the diaphragm 126 is vibrated to eject the ink inside the pressure chamber 155 from the nozzle N.

[0126] The heat generated from the drive circuit 142 is conducted to the main body portion 181a of the heat dissipation member 181 through the FPC 141. The heat conducted by the main body portion 181a is conducted from the end portion 181b to the diaphragm 126. The heat conducted to the diaphragm 126 is transferred from the vibration portion 126a that forms a part of the wall surface of the pressure chamber 155 to the ink inside the pressure chamber 155.

[0127] A part of the heat transmitted to the diaphragm 126 is transmitted to the ink passing through the filter portion 126b from the filter portion 126b. A part of the heat transmitted to the diaphragm 126 is transmitted to the ink passing through the filter portion 126c.

[0128] Also, part of the heat transmitted to the diaphragm 126 is conducted to the common liquid chamber forming member 127 made of metal. As a result, heat is transferred from the wall surfaces of the common liquid chambers 152, 153, 158 to the ink inside the common liquid chambers 152, 153, 158.

[0129] Also, part of the heat transmitted to the diaphragm 126 is conducted to the flow path member 124 made of metal. A plurality of pressure chambers 155 are formed in the flow path member 124. The pressure chambers 155 are arranged at predetermined intervals in the Y-axis direction. A partition wall is provided between the pressure chambers 155 adjacent to each other in the Y-axis direction. For example, in the Y-axis direction, heat can also be transferred from the partition wall disposed between the pressure chambers 155 to the ink in the pressure chambers 155. Also, heat can be transferred to the ink inside the flow path member 124 via the partition walls 124a, 124b.

[0130] The ink that has been heat-transferred through the diaphragm 126 is ejected from the nozzle N or flows through the individual recovery flow path 157 and is circulated. As a result, heat is discharged to the outside of the liquid ejection head 10B. Alternatively, part of the heat can be dispersed inside the liquid ejection head 10B and dissipated from various parts of the liquid ejection head 10B.

[0131] Even in such a liquid ejection head 10B, similar to the liquid ejection head 10 of the first embodiment described above, the temperature rise of the drive circuit 142 can be suppressed. In the liquid ejection head 10B, the heat transfer area between the diaphragm 126 and the ink can be increased.

[0132] Next, a liquid ejection head 10C according to a modified example will be described with reference to FIG. 13. FIG. 13 is a cross-sectional view showing the liquid ejection head 10C according to the modified example. The differences between the liquid ejection head 10C shown in FIG. 13 and the liquid ejection head 10 of the first embodiment are that the heat dissipation member 85 is connected to the protective substrate 27 closer to the recovery-side pressure chamber 57B, and that a heat dissipation member 86 that directly contacts the drive circuit 42 is provided. In the description of the modified example, the same description as that of the liquid ejection head 10 of the first embodiment will be omitted.

[0133] The drive circuit 42 is provided on the surface 41a of the flexible wiring board 41. The surface 41a is, for example, a surface in the X1 direction. The heat radiating member 85 is provided on the surface 41b of the flexible wiring board 41. The surface 41b is the surface on the opposite side of the surface 41a where the drive circuit 42 is provided. The end portion 85b in the Z1 direction of the heat radiating member 85 is in contact with the protective substrate 27 closer to the recovery-side pressure chamber 57B. In this way, the heat radiating member 85 may be connected to the protective substrate closer to the recovery-side pressure chamber 57B.

[0134] The heat radiating member 86 is in direct contact with the drive circuit 42. The fact that the heat radiating member 86 and the drive circuit 42 are in direct contact means that the flexible wiring board 41 is not disposed between the heat radiating member 86 and the drive circuit 42. The surface 42a of the drive circuit 42 is the surface that contacts the flexible wiring board 41 and is a surface in the X2 direction. The surface 42b of the drive circuit 42 is the surface on the opposite side of the surface 42a and is a surface in the X1 direction. The heat radiating member 86 is disposed in the X1 direction of the drive circuit 42 and is in contact with the surface 42b of the drive circuit 42. The end portion 86b in the Z1 direction of the heat radiating member 86 is in contact with the protective substrate 27 closer to the supply-side pressure chamber 57A. In this way, the heat radiating member 86 may be in contact with the surface 42b of the drive circuit 42.

[0135] Even in such a modified liquid ejection head 10C, the same operational effects as those of the above-described liquid ejection head 10 are achieved. In the liquid ejection head 10C, the heat radiating members 85 and 86 are disposed on both sides of the drive circuit 42 in the X-axis direction. Thereby, the drive circuit 42 is efficiently cooled.

[0136] Note that the above-described embodiments merely show typical forms of the present invention, and the present invention is not limited to the above-described embodiments, and various changes and additions can be made without departing from the gist of the present invention.

[0137] In the above-described embodiments, the line-type liquid ejection device 1 including the line head 6 is illustrated, but the present invention may also be applied to a serial-type liquid ejection device that reciprocates a carriage on which the liquid ejection head 10 is mounted in the width direction of the medium PA.

[0138] In the foregoing embodiment, the liquid ejection head 10 is exemplified as having a configuration including a holder 12 and a case 28 as a flow path member through which ink flows, but is not limited thereto. The liquid ejection head 10 may have a configuration including the holder 12 as a flow path member and not including the case 28. The liquid ejection head 10 may have a configuration including the case 28 as a flow path member and not including the holder 12.

[0139] The liquid ejection device 1 exemplified in the foregoing embodiment can be adopted in various devices such as a facsimile device and a copying machine in addition to a device dedicated to printing. However, the use of the liquid ejection device of the present invention is not limited to printing. For example, a liquid ejection 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. In addition, a liquid ejection 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 ejection device that discharges a solution of an organic substance related to a living body is used, for example, as a manufacturing device for manufacturing a biochip.

Description of Reference Numerals

[0140] 1…Liquid injection device, 10, 10B, 10C…Liquid injection head, 12…Holder (flow path member), 26, 126…Diaphragm, 27…Protection substrate, 27c…Recess, 28…Case (flow path member), 30, 130…Piezoelectric actuator (piezoelectric element), 40…COF, 41…Flexible wiring board (flexible board), 42, 142…Drive circuit, 51A…Individual supply flow path, 51B…Individual recovery flow path, 53A…Common liquid chamber (common flow path), 57A, 57B, 155…Pressure chamber, 73…Opening of the case (opening of the flow path member), 75…Opening of the holder (opening of the flow path member), 81, 85, 86, 181…Heat dissipation member, 81b, 85b, 86b, 181b…End portion (end portion closer to the diaphragm), 93…Branch flow path (common flow path), 94…Converging flow path (common flow path), 126a…Vibrating portion, 126b, 126c…Filter portion, 154…Individual supply flow path, 155…Individual recovery flow path, N…Nozzle, N1…Nozzle row, W1…Width of the end portion of the heat dissipation member, W2…Width of the opening (width of the opening of the protection substrate), X…X-axis direction (second direction), Y…Y-axis direction (first direction), Z1…Z1 direction (injection direction).

Claims

1. A piezoelectric element driven to eject a liquid in an ejection direction from a plurality of nozzles, A plurality of pressure chambers communicating with respective ones of the plurality of nozzles, A plurality of individual supply channels for supplying a liquid to respective ones of the plurality of nozzles, A plurality of individual recovery channels for recovering liquid that has not been discharged from respective ones of the plurality of nozzles, And a plurality of individual recovery channels, A diaphragm that defines the wall surfaces of the plurality of pressure chambers and is displaced by driving of the piezoelectric element, A flexible substrate having a drive circuit electrically connected to the piezoelectric element, A surface of the flexible substrate opposite to the surface on which the drive circuit is provided, or a heat dissipation member that contacts the drive circuit and conducts heat of the drive circuit to the diaphragm, And a heat dissipation member that contacts the drive circuit and conducts heat of the drive circuit to the diaphragm, Comprising, The heat dissipation member is disposed closer to the individual supply channels than the individual recovery channels, A liquid ejection head.

2. An opening through which the flexible substrate is inserted and a common channel communicating with the plurality of pressure chambers, A channel member made of resin, and a circuit board laminated on the channel member and electrically connected to the flexible substrate, Comprising, The drive circuit is disposed inside the opening of the channel member, The liquid ejection head according to claim 1.

3. A recess that is recessed in a direction opposite to the ejection direction so as to surround the piezoelectric element when viewed in the ejection direction, And a protective substrate that is laminated on the diaphragm to seal the piezoelectric element between the protective substrate and the diaphragm, Comprising, The protective substrate is formed of metal or ceramics, The heat dissipation member contacts the protective substrate, The liquid ejection head according to claim 1 or 2.

4. The protective substrate is a member that does not define a flow path through which liquid flows. The liquid ejection head according to claim 3.

5. The portion of the heat dissipation member that contacts the protective substrate is disposed closer to the individual supply flow path than the individual recovery flow path. of the flow path. The liquid ejection head according to claim 3 or 4.

6. The plurality of nozzles are arranged along a first direction to form a nozzle row. The width in a second direction, which is perpendicular to the first direction and the ejection direction, at the end of the heat dissipation member closer to the diaphragm is larger than the width in the second direction of the opening through which the flexible substrate of the protective substrate is inserted. of the opening. of the opening. The liquid ejection head according to any one of claims 3 to 5.

7. The heat dissipation member is directly connected to the diaphragm. The diaphragm is made of metal. The liquid ejection head according to claim 1.

8. A part of the diaphragm includes a filter portion that allows liquid to pass through at a position different from the wall surface of the pressure chamber. of the pressure chamber. The liquid ejection head according to claim 7.

9. The portion of the heat dissipation member that contacts the diaphragm is disposed closer to the individual supply flow path than the individual recovery flow path. of the flow path. The liquid ejection head according to claim 7 or 8.

10. The heat dissipation member is made of metal. The liquid ejection head according to any one of claims 1 to 9.

11. The heat dissipation member is made of ceramics. The liquid ejection head according to any one of claims 1 to 9.

12. The liquid ejection head according to any one of claims 1 to 11, and a liquid storage unit that stores the liquid supplied to the liquid ejection head, A liquid ejection apparatus comprising the same.

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