Liquid ejection head and liquid ejection device

Abstract

The present invention provides an inkjet head and an inkjet apparatus that achieve power saving of the inkjet head. The inkjet head includes: a plurality of head chips including first and second head chips; a holder that holds the plurality of head chips; a heater along a direction parallel to the nozzle surface of the head chips. The first and second head chips are arranged so as to be offset from each other in both a first direction and a second direction that are parallel to the nozzle surface and intersect each other. When one of the four sides of an imaginary rectangle circumscribing the collective body of the plurality of head chips in a plan view is defined as a first side, and the sides connected to both ends of the first side are defined as a second side and a third side, in a plan view, the first head chip is in contact with the first side and the third side, the second head chip is in contact with the second side, the heater overlaps the plurality of head chips, and a first region surrounded by the first side, the second side, the first head chip, and the second head chip includes a first outer portion located outside the outer edge of the heater.

Description

Technical Field

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

[0002] In a liquid ejection device typified by an inkjet printer, a liquid ejection head that ejects a liquid such as ink as droplets is generally provided. In the liquid ejection head, for example, the head described in Patent Document 1 has: a plurality of head chips, each of the head chips being arranged in a staggered manner; and a rectangular holder that holds the plurality of head chips.

[0003] However, in recent years, a heater has sometimes been arranged in the head in order to eject a highly viscous liquid such as ultraviolet curable ink. Further, for a head including head chips that are offset from each other in a direction crossing the arrangement direction of the plurality of head chips as described in Patent Document 1, there is a demand for power saving and efficient heating of the head by the heater.

[0004] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2017-19153 Summary of the Invention

[0005] In order to solve the above problems, a liquid ejection head according to a preferred aspect of the present invention includes: a plurality of head chips, each of the head chips having a nozzle surface on which a nozzle for ejecting a liquid is provided; a heat-conductive holder that holds the plurality of head chips; and a planar heater that is arranged at a position where the holder is interposed between the heater and the plurality of head chips and extends in a direction parallel to the nozzle surface, and when two directions intersecting each other along the nozzle surface are defined as a first direction and a second direction, each of the plurality of head chips is elongated along the first direction, the plurality of head chips include a first head chip and a second head chip, the first head chip and the second head chip are arranged so as to be offset from each other in both the first direction and the second direction, when one of the four sides of a hypothetical rectangle circumscribing the collective body of the plurality of head chips in a top view is defined as a first side, a side connected to one end of the first side is defined as a second side, and a side connected to the other end of the first side is defined as a third side, the first head chip abuts on the first side and the third side in the top view, the second head chip abuts on the second side in the top view, the heater overlaps the plurality of head chips in the top view, and a first region surrounded by the first side, the second side, the first head chip, and the second head chip in the top view includes a first outer portion located outside the outer edge of the heater.

[0006] The liquid ejection device according to a preferred embodiment of the present invention includes the liquid ejection head of the foregoing embodiment and a liquid reservoir that stores the liquid supplied to the liquid ejection head. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 It is a schematic diagram showing a structural example of the liquid ejection device according to the first embodiment.

[0008] Figure 2 It is a perspective view of the liquid ejection head and the support according to the first embodiment.

[0009] Figure 3 It is an exploded perspective view of the liquid ejection head according to the first embodiment.

[0010] Figure 4 It is Figure 2 a cross-sectional view taken along line A-A in

[0011] Figure 5 It is Figure 2 a cross-sectional view taken along line B-B in

[0012] Figure 6 It is a cross-sectional view showing an example of the head chip.

[0013] Figure 7 It is a bottom view of the holder in the first embodiment.

[0014] Figure 8 It is a top view of the holder in the first embodiment.

[0015] Figure 9 It is a diagram for explaining the shape of the holding portion of the holder in the first embodiment.

[0016] Figure 10 It is a diagram for explaining the shape of the heater and the heat conductive member in the first embodiment.

[0017] Figure 11 It is a diagram for explaining the heat transfer path from the heater in the first embodiment.

[0018] Figure 12 It is an exploded perspective view of the liquid ejection head according to the second embodiment.

[0019] Figure 13 It is a diagram for explaining the heat transfer path from the heater in the third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0020] Hereinafter, with reference to the accompanying drawings, preferred embodiments of the present invention will be described. In the drawings, the dimensions and scales of each part are appropriately different from the actual ones, and there are also parts schematically shown for ease of understanding. In addition, the scope of the present invention is not limited to these embodiments as long as there is no specific description in the following description for specifically limiting the present invention.

[0021] For convenience, the following description is implemented by appropriately using the mutually intersecting X-axis, Y-axis, and Z-axis. In addition, in the following description, one direction along the X-axis is the X1 direction, and the direction opposite to the X1 direction is the X2 direction. Similarly, the directions opposite to each other along the Y-axis are the Y1 direction and the Y2 direction. In addition, the directions opposite to each other along the Z-axis are the Z1 direction and the Z2 direction. In addition, the case of observing in the Z-axis direction is sometimes simply referred to as "top view observation". In addition, the Y direction or the Y2 direction is an example of "the first direction". The X1 direction or the X2 direction is an example of "the second direction".

[0022] 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 may not be a vertical axis. In addition, although the X-axis, Y-axis, and Z-axis are typically orthogonal to each other, it is not limited thereto. For example, they may intersect at an angle within the range of 80° or more and 100° or less.

[0023] 1. First Embodiment

[0024] 1-1. Schematic Structure of the Liquid Jetting Device

[0025] Figure 1 It is a schematic diagram showing a structural example of the liquid jetting device 100 according to the first embodiment. The liquid jetting device 100 is an inkjet printing device that jets ink, which is an example of "liquid", as droplets onto the medium M. The medium M is typically printing paper. In addition, the medium M is not limited to printing paper. For example, it may be a printing object made of any material such as a resin film or a cloth.

[0026] As Figure 1 shown, the liquid jetting device 100 includes a liquid storage unit 10, a control unit 20, a conveying mechanism 30, a moving mechanism 40, and a liquid jetting head 50.

[0027] The liquid storage unit 10 is a container for storing ink. As a specific form of the liquid storage unit 10, for example, containers such as a cartridge that can be attached to and detached from the liquid jetting device 100, an ink bag formed of a flexible film, and an ink tank that can replenish ink can be cited.

[0028] Although not shown, the liquid storage unit 10 has a plurality of containers for storing inks of different types from each other. The inks stored in the plurality of containers are not particularly limited, but for example, cyan ink, magenta ink, yellow ink, black ink, transparent ink, white ink, treatment liquid, etc. can be cited, and a combination of two or more of them is used. In addition, the components of the ink are not particularly limited. For example, it can be an aqueous ink in which a color material such as a dye or a pigment is dissolved in an aqueous solvent, a solvent-based ink in which the color material is dissolved in an organic solvent, or an ultraviolet curable ink.

[0029] In the present embodiment, a structure using four different inks is illustrated. These four inks are, for example, inks having different colors from each other such as cyan ink, magenta ink, yellow ink, and black ink.

[0030] The control unit 20 controls the operations of the respective elements of the liquid ejection device 100. For example, the control unit 20 includes 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. The control unit 20 outputs a drive signal D and a control signal S to the liquid ejection head 50. The drive signal D is a signal including drive pulses for driving the drive elements of the liquid ejection head 50. The control signal S is a signal for specifying whether to supply the drive signal D to the drive elements.

[0031] The conveyance mechanism 30 conveys the medium M in the conveyance direction DM as the Y1 direction under the control implemented by the control unit 20. The moving mechanism 40 reciprocates the liquid ejection head 50 in the X1 direction and the X2 direction under the control implemented by the control unit 20. In Figure 1 the example shown, the moving mechanism 40 has a substantially box-shaped support body 41 called a carriage for housing the liquid ejection head 50, and a conveyor belt 42 for fixing the support body 41. In addition, on the support body 41, in addition to the liquid ejection head 50, the aforementioned liquid storage unit 10 may also be mounted.

[0032] As described later, the liquid ejection head 50 has a plurality of head chips 54, and under the control implemented by the control unit 20, ejects the ink supplied from the liquid storage unit 10 from each of the plurality of nozzles of each head chip 54 toward the medium M in the Z2 direction as the ejection direction. By performing this ejection in parallel with the conveyance of the medium M by the conveyance mechanism 30 and the reciprocating movement of the liquid ejection head 50 by the moving mechanism 40, a predetermined image formed by the ink is formed on the surface of the medium M.

[0033] In addition, the liquid reservoir 10 may also be connected to the liquid ejection head 50 via a circulation mechanism. The circulation mechanism is a mechanism that supplies ink to the liquid ejection head 50 and recovers the ink discharged from the liquid ejection head 50 for re-supplying it to the liquid ejection head 50. By the operation of this circulation mechanism, it is possible to suppress the increase in the viscosity of the ink or reduce the retention of air bubbles in the ink.

[0034] 1-2. Mounting state of the liquid ejection head

[0035] Figure 2 FIG. is a perspective view of the liquid ejection head 50 and the support 41 according to the first embodiment. As Figure 2 shown, the liquid ejection head 50 is supported on the support 41. The support 41 is a member that supports the liquid ejection head 50. As described above, in the present embodiment, it is a substantially box-shaped carriage. Although the constituent material of the support 41 is not particularly limited, for example, it is preferably made of a metal material such as stainless steel, aluminum, titanium, or magnesium alloy. When the support 41 is made of a metal material, it is easy to improve the rigidity of the support 41. Therefore, the liquid ejection head 50 can be stably supported with respect to the support 41. In addition, in this case, since the support 41 has conductivity, a reference potential can be supplied to the liquid ejection head 50 via the support 41.

[0036] Here, in the support 41, an opening 41a and a plurality of threaded holes 41b are provided. In the present embodiment, the support 41 has a substantially box shape with a plate-like bottom. For example, the opening 41a and the plurality of threaded holes 41b are provided at the bottom. The liquid ejection head 50 is fixed to the support 41 by screw fixation using the plurality of threaded holes 41b in a state of being inserted into the opening 41a. As described above, the liquid ejection head 50 is mounted with respect to the support 41.

[0037] In Figure 2 the example shown, the number of liquid ejection heads 50 mounted on the support 41 is one. In addition, the number of liquid ejection heads 50 mounted on the support 41 may also be two or more. In this case, in the support 41, for example, openings 41a having a corresponding number or shape are appropriately provided according to the number.

[0038] 1-3. Structure of the liquid ejection head

[0039] Figure 3 FIG. is an exploded perspective view of the liquid ejection head 50 according to the first embodiment. Figure 4 is Figure 2 a cross-sectional view taken along line A-A in Figure 5 is Figure 2A cross-sectional view taken along line B-B in []. Additionally, in Figures 3 to 5 for convenience, each part of the liquid ejection head 50 is shown appropriately and briefly. For example, as will be described later Figure 11 shows that there is a gap d2 between the outer wall portion 5b and the flow channel structure 51, but in Figure 4 and Figure 5 for convenience of drawing, the illustration of this gap is omitted.

[0040] As Figure 3 shows, the liquid ejection head 50 includes a flow channel structure 51, a substrate unit 52, a holder 53, four head chips 54_1 to 54_4, a fixing plate 55, a heater 56, a heat conductive member 57, and a cover 58. These components are arranged in the order of the cover 58, the substrate unit 52, the flow channel structure 51, the heat conductive member 57, the heater 56, the holder 53, the four head chips 54, and the fixing plate 55 in the direction of Z2. Hereinafter, each part of the liquid ejection head 50 will be described in turn.

[0041] In addition, the heat conductive member 57 is an example of the "second heat conductive member". Furthermore, the head chips 54_1 to 54_4 are respectively the Figure 1 shown head chips 54. Here, the head chip 54_1 is an example of the "first head chip". The head chip 54_2 is an example of the "second head chip". The head chip 54_3 is an example of the "third head chip". The head chip 54_4 is an example of the "fourth head chip". Hereinafter, when the head chips 54_1 to 54_4 are not distinguished, each of these chips is labeled as the head chip 54.

[0042] The flow channel structure 51 is a structure in which flow channels for supplying the ink stored in the aforementioned liquid storage portion 10 to the four head chips 54 are provided inside. The flow channel structure 51 includes a flow channel member 51a and eight connecting pipes 51b.

[0043] In the flow channel member 51a, although not shown, four supply flow channels provided for each of the four types of ink and four discharge flow channels provided for each of the four types of ink are provided. Each of the four supply flow channels has one inlet for receiving the supply of ink and two outlets for discharging the ink. Each of the four discharge flow channels has two inlets for receiving the supply of ink and one outlet for discharging the ink. The inlets of the respective supply flow channels and the outlets of the respective discharge flow channels are respectively provided on the surface of the flow channel member 51a facing the Z1 direction. In contrast, the outlets of the respective supply flow channels and the inlets of the respective discharge flow channels are respectively provided on the surface of the flow channel member 51a facing the Z2 direction.

[0044] In addition, in the flow path member 51a, a plurality of wiring holes 51c are provided. Each of the plurality of wiring holes 51c is a hole through which a wiring board 54i (described later) of the head chip 54 passes toward the substrate unit 52. Further, on the side surface of the flow path member 51a, cut portions are provided at two locations in the circumferential direction. In the space formed by this portion, for example, components such as wiring (not shown) that connects the heater 56 and the substrate unit 52 are arranged. In addition, a hole (not shown) is provided in the flow path member 51a, and the flow path member 51a is fixed to the holder 53 by screw fixation using this hole.

[0045] Although not shown, the flow path member 51a is composed of a laminate in which a plurality of substrates are laminated in the direction along the Z axis. In each of the plurality of substrates, grooves and holes for the aforementioned supply flow path and discharge flow path are appropriately provided. The plurality of substrates are joined to each other, for example, by an adhesive, brazing, welding, or screw fixation. Further, between the plurality of substrates, a sheet-like sealing member made of a rubber material or the like may be appropriately arranged as needed. In addition, the number, thickness, etc. of the substrates constituting the flow path member 51a are determined according to the shape of the supply flow path and the discharge flow path, etc., and are not particularly limited and are arbitrary.

[0046] As the constituent material of each of the plurality of substrates, it is preferable to use a material having good thermal conductivity. For example, it is preferable to use a metal material such as stainless steel, titanium, and magnesium alloy, or a ceramic material such as silicon carbide, aluminum nitride, sapphire, alumina, silicon nitride, cermet, and yttrium oxide, whose thermal conductivity at room temperature (20°C) is 10.0 W / m·K or more. By forming the flow path member 51a using such a metal material or ceramic material, the ink in the flow path member 51a can be effectively heated by the heat from the heater 56.

[0047] Each of the eight connection pipes 51b is a pipe body protruding from the surface of the flow path member 51a facing the Z1 direction. The eight connection pipes 51b correspond to the aforementioned four supply flow paths and four discharge flow paths, and are connected to the inlet of the corresponding supply flow path or the outlet of the discharge flow path. Although not particularly limited, as the constituent material of each connection pipe 51b, for example, a metal material such as stainless steel, titanium, and magnesium alloy, or a ceramic material such as silicon carbide, aluminum nitride, sapphire, alumina, silicon nitride, cermet, and yttrium oxide is preferable.

[0048] Among the above eight connecting tubes 51b, four connecting tubes 51b corresponding to the aforementioned four supply channels are connected to the liquid reservoir 10 in such a way as to receive supplies of mutually different types of ink. On the other hand, four connecting tubes 51b among the eight connecting tubes 51b corresponding to the aforementioned four discharge channels are used in such a way that they are connected to a discharge container for discharging ink at a predetermined time such as during the initial filling of the ink into the liquid ejection head 50, or to a sub-tank or the like that is disposed between the liquid reservoir 10 and the liquid ejection head 50 and is capable of holding the liquid. During normal times such as during printing, the four connecting tubes 51b corresponding to the aforementioned four discharge channels are sealed by a sealing body such as a lid. In addition, when the liquid reservoir 10 is connected to the liquid ejection head 50 via a circulation mechanism, the four connecting tubes 51b corresponding to the four discharge channels are connected to the ink recovery channel of the circulation mechanism during normal times.

[0049] The substrate unit 52 is an assembly having mounting parts for electrically connecting the liquid ejection head 50 and the control unit 20. The substrate unit 52 includes a circuit board 52a, a connector 52b, and a support plate 52c.

[0050] The circuit board 52a is a printed wiring board such as a rigid wiring board having wirings for electrically connecting the respective head chips 54 and the connector 52b. The circuit board 52a is disposed on the flow channel structure 51 via the support plate 52c, and the connector 52b is provided on the surface of the circuit board 52a facing the Z1 direction.

[0051] The connector 52b is a connecting part for electrically connecting the liquid ejection head 50 and the control unit 20. The support plate 52c is a plate-like member for mounting the circuit board 52a relative to the flow channel structure 51. The circuit board 52a is placed on one surface of the support plate 52c, and the circuit board 52a is fixed relative to the support plate 52c by screw fixing or the like. In addition, the other surface of the support plate 52c contacts the flow channel structure 51, and in this state, the support plate 52c is fixed to the flow channel structure 51 by screw fixing or the like.

[0052] Here, the support plate 52c not only has the function of supporting the circuit board 52a as described above, but also has the functions of ensuring electrical insulation between the circuit board 52a and the flow channel structure 51 and heat insulation between the heater 56 and the circuit board 52a. From the viewpoint of properly exerting these functions, the constituent material of the support plate 52c is preferably a material with excellent insulation and heat insulation properties. Specifically, for example, resin materials such as modified polyphenylene ether resin like Zylon, polyphenylene sulfide resin, and polypropylene resin are preferred. In addition, Zylon is a registered trademark. Furthermore, in the constituent material of the support plate 52c, in addition to the resin material, fiber base materials such as glass fiber or fillers such as alumina particles may also be included.

[0053] The retainer 53 is a structure for accommodating and supporting the four head chips 54. As the constituent material of the retainer 53, it is preferably a material with good thermal conductivity. For example, metal materials such as stainless steel, titanium, and magnesium alloy with a thermal conductivity of 10.0 W / m·K or more at room temperature (20°C), or ceramic materials such as silicon carbide, aluminum nitride, sapphire, alumina, silicon nitride, cermet, and yttrium oxide are preferred. By forming the retainer 53 with such metal materials or ceramic materials, the heat from the heater 56 can be effectively transferred to each head chip 54 via the retainer 53.

[0054] The retainer 53 is in a substantially tray shape and has a recess 53a, a plurality of ink holes 53b, a plurality of wiring holes 53c, a plurality of recesses 53d, a plurality of threaded holes 53i, and a plurality of threaded holes 53k. The recess 53a opens in the Z1 direction and is a space for arranging the laminate of the aforementioned flow channel member 51a, heater 56, and heat conducting member 57. Each of the plurality of ink holes 53b is a flow channel for allowing ink to flow between the head chip 54 and the flow channel structure 51. Each of the plurality of wiring holes 53c is a hole through which the wiring substrate 54i of the head chip 54 passes toward the substrate unit 52. Each of the plurality of recesses 53d opens in the Z2 direction and is a space for arranging the head chip 54. The plurality of threaded holes 53i are threaded holes for screwing the retainer 53 to the support body 41. The plurality of threaded holes 53k are threaded holes for screwing the cover 58 to the retainer 53. In addition, the detailed situation of the retainer 53 will be described based on the following Figure 7 of Figure 9 and will be explained.

[0055] Each head chip 54 ejects ink. Each head chip 54 has a plurality of nozzles for ejecting a first ink and a plurality of nozzles for ejecting a second ink of a type different from the first ink. Here, the first ink and the second ink are two of the aforementioned four inks. For example, in each of head chips 54_1 and 54_2, two of the four inks are used as the first ink and the second ink. Moreover, in each of head chips 54_3 and 54_4, the remaining two of the four inks are used. In each head chip 54, a wiring substrate 54i is provided. In addition, in Figure 3 a simplified structure of each head chip 54 is illustrated. Regarding the structure of the head chip 54, it will be described in detail based on Figure 6 which will be described later.

[0056] The fixing plate 55 is a plate-like member that fixes four head chips 54 and the holder 53. Specifically, the fixing plate 55 is arranged in a state of clamping four head chips 54 between it and the holder 53, and each head chip 54 and the holder 53 are fixed by an adhesive or the like.

[0057] In the fixing plate 55, a plurality of openings 55a are provided to expose the nozzle surfaces FN of the four head chips 54. In the Figure 3 example shown, the plurality of openings 55a are independently provided for each head chip 54. The fixing plate 55 is made of a metal material such as stainless steel, titanium, and magnesium alloy, etc., and has a function of transferring heat from the holder 53 to each head chip 54. In addition, the fixing plate 55 has conductivity. Therefore, the fixing plate 55 is grounded via the holder 53 and the support 41, and also functions as an electrostatic shield for preventing the influence of static electricity etc. from the medium M. In addition, the fixing plate 55 can be formed by laminating a plurality of plate-like members made of a metal material.

[0058] The outer shape of the above fixing plate 55 is rectangular or substantially rectangular when viewed from above. Here, "substantially rectangular" refers to a concept that includes a shape that can be substantially called a rectangle and a shape similar to a rectangle. A shape that can be substantially called a rectangle is, for example, a shape obtained by chamfering the four corners of a rectangle by C chamfering or R chamfering, etc. A shape similar to a rectangle is, for example, a shape such as an octagon that includes four sides along the four sides of a rectangle and four sides shorter than each of the four sides. In addition, the opening 55a can also be shared by two or more head chips 54. However, when the opening 55a is independently provided for each head chip 54, since it is easy to increase the contact area between the fixing plate 55 and each head chip 54, heat can be effectively transferred from the holder 53 to each head chip 54.

[0059] The heater 56 is a planar heater disposed between the flow channel structure 51 and the retainer 53. The heater 56 is, for example, a thin film heater having an insulating thin film and a thin film-like heating resistor. The thin film is made of a resin material such as polyimide or PET (polyethylene terephthalate), for example. The heating resistor is formed in a pattern on the thin film and is made of a metal material such as stainless steel, copper, or nickel alloy, for example. In addition, the heater 56 may also be a planar heater such as a silicone rubber heater or a ceramic heater in which a heating element is sandwiched between silicone rubber containing glass fibers.

[0060] The heater 56 is provided with a plurality of holes 56a and a plurality of holes 56b. Each of the plurality of holes 56a is a hole through which the wiring substrate 54i of the head chip 54 and the flow channel tube 53l formed in the retainer 53 pass. The ink hole 53b formed inside the flow channel tube 53l is a part of the flow channel that allows ink to flow between the head chip 54 and the flow channel structure 51. The flow channel tube 53l projects in the Z1 direction from the upper surface (the first surface F1 described later) of the retainer 53 facing the Z1 direction, for example. Then, by bonding the tip on the Z1 direction side of the flow channel tube 53l to the lower surface of the flow channel structure 51 facing the Z2 direction, the ink hole 53b and the flow channel inside the flow channel structure 51 are hermetically sealed. Each of the plurality of holes 56b is a hole for screw-fixing the heater 56 to the retainer 53. In addition, regarding the shape of the heater 56 in a top view, it will be described in detail based on Figure 10 , which will be described in detail later.

[0061] The heat conducting member 57 is a plate-like member having heat conductivity and disposed between the flow channel structure 51 and the heater 56. The heat conducting member 57 has a function of transferring heat in each of the thickness direction and the plane direction. According to this function, the heat from the heater 56 is effectively transferred to the flow channel structure 51 via the heat conducting member 57. Here, due to the heat conduction in the plane direction of the heat conducting member 57, the uneven heating of the flow channel structure 51 caused by the heat generation distribution of the heater 56 is reduced.

[0062] The heat conducting member 57 is made of a heat conductive material such as a metal material or ceramics such as silicon carbide, aluminum nitride, sapphire, alumina, silicon nitride, cermet, and yttrium oxide, for example. As the metal material, for example, stainless steel, aluminum, titanium, and magnesium alloy can be cited. Preferably, the heat conducting member 57 is a material having a higher heat conductivity with respect to the flow channel structure 51 or the retainer 53. Since by providing such a heat conducting member 57 having a higher heat conductivity, it is easy to move the heat from the heater 56 in the direction parallel to the nozzle surface FN, the heat from the heater 56 can be uniformly and effectively transferred to the flow channel structure 51 as the object to be heated via the heat conducting member 57.

[0063] In the heat conducting member 57, a plurality of holes 57a, a plurality of wiring holes 57b, and a plurality of holes 57c are provided. Each of the plurality of holes 57a is a hole through which the aforementioned flow channel tube 53l is inserted. Each of the plurality of wiring holes 57b is a hole through which the wiring substrate 54i of the head chip 54 passes toward the substrate unit 52. The plurality of holes 57c are holes for screw-fixing the heat conducting member 57 to the holder 53. In the present embodiment, two of the plurality of holes 57c are used to fix the heater 56 and the heat conducting member 57 to the holder 53 by tightening them together. Additionally, regarding the top view shape of the heat conducting member 57, it will be described in detail based on the following Figure 10 .

[0064] The cover 58 is a box-shaped member for housing the substrate unit 52. The cover 58 is made of a resin material such as a modified polyphenylene ether resin, a polyphenylene sulfide resin, or a polypropylene resin, for example, in the same manner as the aforementioned support plate 52c.

[0065] On the cover 58, eight through holes 58a and an opening 58b are provided. The eight through holes 58a correspond to the eight connecting tubes 51b of the flow channel structure 51, and the corresponding connecting tubes 51b are inserted into the respective through holes 58a. In the opening 58b, the aforementioned connector 52b passes from the inside to the outside of the cover 58.

[0066] 1-4. Structure of the Head Chip

[0067] Figure 6 is a cross-sectional view showing an example of the head chip 54. As Figure 6 shown, the head chip 54 has a plurality of nozzles N arranged in the direction along the Y axis. The plurality of nozzles N are divided into a first row L1 and a second row L2 that are arranged side by side at intervals in the direction along the X axis. The first row L1 and the second row L2 are each a set of a plurality of nozzles N arranged linearly in the direction along the Y axis.

[0068] The head chip 54 has a structure that is substantially symmetric in the direction along the X axis. However, the positions of the plurality of nozzles N in the first row L1 and the plurality of nozzles N in the second row L2 in the direction along the Y axis may be the same or different. In Figure 6 , a structure in which the positions of the plurality of nozzles N in the first row L1 and the plurality of nozzles N in the second row L2 in the direction along the Y axis are the same is illustrated.

[0069] As Figure 6 shown, the head chip 54 has a flow channel substrate 54a, a pressure chamber substrate 54b, a nozzle plate 54c, a vibration absorber 54d, a diaphragm 54e, a plurality of piezoelectric elements 54f, a protection plate 54g, a housing 54h, a wiring substrate 54i, and a drive circuit 54j.

[0070] The flow channel substrate 54a and the pressure chamber substrate 54b are laminated in the Z1 direction in sequence, and a flow channel for supplying ink to a plurality of nozzles N is formed. In a region located in the Z1 direction compared with the laminate composed of the flow channel substrate 54a and the pressure chamber substrate 54b, a diaphragm 54e, a plurality of piezoelectric elements 54f, a protection plate 54g, a housing 54h, a wiring substrate 54i, and a drive circuit 54j are provided. On the other hand, in a region located in the Z2 direction compared with this laminate, a nozzle plate 54c and a vibration absorber 54d are provided. Each element of the head chip 54 is a plate-like member that is substantially long in the Y direction and is joined to each other by, for example, an adhesive. Hereinafter, each element of the head chip 54 will be described in sequence.

[0071] The nozzle plate 54c is a plate-like member provided with a plurality of nozzles N in each of the first row L1 and the second row L2. Each of the plurality of nozzles N is a through hole through which ink passes. Here, the surface of the nozzle plate 54c facing the Z2 direction is the nozzle surface FN. That is, the normal direction of the nozzle surface FN is the direction of the normal vector of the nozzle surface FN and is the ejection direction, that is, the Z2 direction. The nozzle plate 54c is manufactured by processing a single crystal silicon substrate by a semiconductor manufacturing technique such as dry etching or wet etching. However, in the manufacture of the nozzle plate 54c, other known methods and materials may also be appropriately used. In addition, although the cross-sectional shape of the nozzle is typically a circular shape, it is not limited thereto. For example, it may be a non-circular shape such as a polygon or an ellipse.

[0072] In the flow channel substrate 54a, for each of the first row L1 and the second row L2, a space R1, a plurality of supply channels Ra, and a plurality of communication channels Na are provided. The space R1 is a long and narrow opening extending in the Y-axis direction when viewed from above in the direction along the Z-axis. The supply channels Ra and the communication channels Na are through holes formed for each nozzle N. Each supply channel Ra communicates with the space R1.

[0073] The pressure chamber substrate 54b is a plate-like member provided with a plurality of pressure chambers C called cavities for each of the first row L1 and the second row L2. The plurality of pressure chambers C are arranged in the Y-axis direction. Each pressure chamber C is a long and narrow space formed for each nozzle N and extending in the X-axis direction when viewed from above. The flow channel substrate 54a and the pressure chamber substrate 54b are each manufactured by processing a single crystal silicon substrate by using a semiconductor manufacturing technique, for example, in the same manner as the aforementioned nozzle plate 54c. However, in the manufacture of each of the flow channel substrate 54a and the pressure chamber substrate 54b, other known methods and materials may also be appropriately used.

[0074] The pressure chamber C is the space between the flow channel substrate 54a and the diaphragm 54e. For each of the first column L1 and the second column L2, a plurality of pressure chambers C are arranged in the direction along the Y-axis. Further, the pressure chamber C communicates with the communication flow channel Na and the supply flow channel Ra, respectively. Accordingly, the pressure chamber C communicates with the nozzle N via the communication flow channel Na and communicates with the space R1 via the supply flow channel Ra.

[0075] The diaphragm 54e is disposed on the surface of the pressure chamber substrate 54b facing the Z1 direction. The diaphragm 54e is a plate-like member capable of vibrating elastically. The diaphragm 54e has, for example, a first layer and a second layer, and these layers are laminated in the Z1 direction in sequence. The first layer is, for example, an elastic film made of silicon oxide (SiO2). This elastic film is formed, for example, by thermally oxidizing one surface of a single crystal silicon substrate. The second layer is, for example, an insulating film made of zirconium oxide (ZrO2). This insulating film is formed, for example, by forming a layer of zirconium by a sputtering method and thermally oxidizing this layer. In addition, the diaphragm 54e is not limited to the structure formed by laminating the aforementioned first layer and second layer. For example, it may be composed of a single layer or may be composed of three or more layers.

[0076] On the surface of the diaphragm 54e facing the Z1 direction, for each of the first column L1 and the second column L2, a plurality of piezoelectric elements 54f corresponding to the nozzle N are arranged as driving elements. Each piezoelectric element 54f is a passive element that deforms by the supply of a drive signal. Each piezoelectric element 54f is in a long strip shape extending in the direction along the X-axis when viewed from above. The plurality of piezoelectric elements 54f are arranged in the direction along the Y-axis so as to correspond to the plurality of pressure chambers C. The piezoelectric element 54f overlaps the pressure chamber C when viewed from above.

[0077] Although not shown, each piezoelectric element 54f has a first electrode, a piezoelectric layer, and a second electrode, which are stacked sequentially in the Z1 direction. One of the first and second electrodes is an independent electrode configured separately for each piezoelectric element 54f, and a drive signal is applied to this electrode. The other of the first and second electrodes is a common electrode in the form of a strip extending continuously along the Y-axis across multiple piezoelectric elements 54f, and a predetermined reference potential is supplied to this electrode. Examples of metal materials for these electrodes include platinum (Pt), aluminum (Al), nickel (Ni), gold (Au), and copper (Cu), and any of these can be used alone or in combination of two or more in the form of an alloy or laminate. The piezoelectric layer is made of a piezoelectric material such as lead zirconate titanate (Pb(Zr, Ti)O3), and is, for example, in the form of a strip extending continuously along the Y-axis across multiple piezoelectric elements 54f. However, the piezoelectric layer may also be formed integrally across multiple piezoelectric elements 54f. In this case, a through-hole extending along the X-axis is provided in the piezoelectric layer in an area corresponding to the gap between adjacent pressure chambers C when viewed from above. When the vibration plate 54e vibrates in conjunction with the deformation of the piezoelectric elements 54f, the pressure within the pressure chambers C fluctuates, causing ink to be ejected from the nozzles N. Alternatively, a heating element that heats the ink within the pressure chambers C may be used as a driving element in place of the piezoelectric elements 54f.

[0078] The protective plate 54g is a plate-shaped member installed on the surface of the vibration plate 54e facing the Z1 direction. It protects the multiple piezoelectric elements 54f and reinforces the mechanical strength of the vibration plate 54e. The multiple piezoelectric elements 54f are housed between the protective plate 54g and the vibration plate 54e. The protective plate 54g is made of, for example, a resin material.

[0079] The housing 54h is used to store ink supplied to the multiple pressure chambers C. The housing 54h is made of, for example, a resin material. A space R2 is provided in the housing 54h for each of the first and second columns L1 and L2. The space R2 communicates with the aforementioned space R1 and, together with the space R1, functions as a reservoir R for storing ink supplied to the multiple pressure chambers C. The housing 54h is provided with an inlet 10 for supplying ink to each reservoir R. The ink in each reservoir R is supplied to the pressure chambers C via the supply flow channels Ra.

[0080] The vibration absorber 54d is also referred to as a plastic substrate and is a flexible resin film that forms the wall surface of the reservoir R, and absorbs pressure fluctuations of the ink in the reservoir R. In addition, the vibration absorber 54d can also be a flexible thin plate made of metal. The surface of the vibration absorber 54d facing the Z1 direction is joined to the flow channel substrate 54a by an adhesive or the like. On the other hand, on the surface of the vibration absorber 54d facing the Z2 direction, a frame 54k is joined by an adhesive or the like. The frame 54k is a frame-shaped member along the outer periphery of the vibration absorber 54d and contacts the aforementioned fixing plate 55. Here, the frame 54k is made of a metal material such as stainless steel, aluminum, titanium, and magnesium alloy, for example. By forming the frame 54k from a metal material in this way, the heat from the heater 56 can be appropriately transferred to the ink in the head chip 54 via the holder 53 and the fixing plate 55. In addition, in Figure 6 , the heat transfer path H1 from the heater 56 to the head chip 54 is schematically shown by a dotted arrow mark. In addition, although a part of the heat transfer path H1 includes the resin-made vibration absorber 54d having a relatively low thermal conductivity, the vibration absorber 54d is formed in a thin film shape in order to have flexibility, so the thickness is thin and the thermal resistance is very small. Therefore, the influence of the vibration absorber 54d on hindering the heat conduction from the frame 54k to the flow channel substrate 54a is small.

[0081] The wiring substrate 54i is mounted on the surface of the diaphragm 54e facing the Z1 direction and is a mounting component for electrically connecting the control unit 20 and the head chip 54. The wiring substrate 54i is a flexible wiring substrate such as a COF (Chip On Film), an FPC (Flexible Printed Circuit), or an FFC (Flexible Flat Cable), for example. On the wiring substrate 54i of the present embodiment, a drive circuit 54j for supplying a drive voltage to each piezoelectric element 54f is mounted. The drive circuit 54j is a circuit that switches based on a control signal S whether to supply at least a part of the waveform included in the drive signal D as a drive pulse.

[0082] 1-5. Structure of the Holder

[0083] Figure 7 is a bottom view of the holder 53 in the first embodiment as viewed from the Z1 direction. Figure 8 is a top view of the holder 53 in the first embodiment as viewed from the Z2 direction. As Figure 7 and Figure 8 shown, the holder 53 having a substantially tray shape as described above has a bottom 5a, an outer wall portion 5b, and a flange portion 5c.

[0084] The bottom 5a is in the form of a substantially plate-like shape that expands in a direction orthogonal to the Z-axis and forms the bottom surface of the aforementioned concave portion 53a. Here, the bottom 5a is divided into a holding portion 5a1 and a connecting portion 5a2. The connecting portion 5a2 is arranged so as to surround the outer periphery of the holding portion 5a1 and has a thinner thickness than the holding portion 5a1.

[0085] The holding portion 5a1 has the aforementioned four concave portions 53d and holds the four head chips 54. Each head chip 54 is accommodated in a space surrounded by each concave portion 53d and the fixing plate 55. In addition, as Figure 7 shown, in the holding portion 5a1, in addition to the four concave portions 53d being provided, two concave portions 53h are also provided. Each concave portion 53h is a so-called concave portion for reducing the wall thickness, is arranged between the four concave portions 53d, and has a depth similar to that of the concave portion 53d. Such a holding portion 5a1 has a heat-receiving portion 5a11 and a side wall portion 5a12.

[0086] The heat-receiving portion 5a11 is in the form of a plate and has a first surface F1 and a second surface F2 that expand in a direction orthogonal to the Z-axis, and forms the bottom surfaces of the concave portion 53d and the concave portion 53h. The first surface F1 is a heat-receiving surface that faces the Z1 direction and receives heat from the heater 56. On the first surface F1, the flow channel structure body 51 is placed via the aforementioned heater 56 and the heat-conducting member 57. The second surface F2 faces the Z2 direction and forms the bottom surfaces of the concave portion 53d and the concave portion 53h.

[0087] In Figure 7 and Figure 8 the example shown, in the heat-receiving portion 5a11, a plurality of ink holes 53b and a plurality of wiring holes 53c are provided so as to open on each of the first surface F1 and the second surface F2. In addition, in the first surface F1 of the heat-receiving portion 5a11, in addition to these openings, a plurality of holes 53e, a plurality of holes 53f, and a plurality of threaded holes 53g are provided.

[0088] The plurality of holes 53e are holes for positioning the head chip 54 relative to the holder 53 by inserting projections (not shown) provided on the head chip 54. The plurality of holes 53f are holes for inserting positioning pins used in the positioning of the flow channel structure body 51, the heater 56, and the heat-conducting member 57. The plurality of threaded holes 53g are threaded holes used in the threaded fixing of the heat-conducting member 57. The plurality of threaded holes 53g are threaded holes used in the threaded fixing of the flow channel structure body 51.

[0089] The side wall portion 5a12 protrudes from the heat receiving portion 5a11 in the Z2 direction and forms the sides of the recessed portion 53d and the recessed portion 53h. At the end of the side wall portion 5a12 in the Z2 direction, a connecting portion 5a2 is connected. Here, when viewed in the direction along the Z-axis, the shape of the side wall portion 5a12 is obtained by removing a plurality of recessed portions 53d and a plurality of recessed portions 53h from the shape of the heat receiving portion 5a11. That is, when viewed in the direction along the Z-axis, the side wall portion 5a12 includes the partition walls between adjacent plurality of recessed portions 53d, the partition walls between the adjacent recessed portion 53d and the recessed portion 53h, and the outer peripheral wall surrounding the plurality of recessed portions 53d and the plurality of recessed portions 53h.

[0090] The connecting portion 5a2 is configured to surround the holding portion 5a1 when viewed in the direction along the Z-axis. The connecting portion 5a2 is in the form of a plate extending from the side wall portion 5a12 in a direction orthogonal to the Z-axis and connects the side wall portion 5a12 and the outer wall portion 5b over the entire circumference. In addition, the connecting portion 5a2 may have a shape with a missing part or may be composed of a plurality of parts arranged at intervals in the circumferential direction.

[0091] The outer wall portion 5b is in the form of a frame extending from the circumference of the bottom portion 5a over the entire circumference in the Z1 direction and forms the side of the aforementioned recessed portion 53a.

[0092] The flange portion 5c is in the form of a plate protruding outward from the end of the outer wall portion 5b in the Z1 direction and in a direction orthogonal to the Z-axis. Thus, on the inner peripheral edge of the flange portion 5c, the outer peripheral edge of the connecting portion 5a2 of the bottom portion 5a is connected via the outer wall portion 5b. In Figure 7 and Figure 8 In the illustrated example, the flange portion 5c is rectangular or substantially rectangular when viewed from above. Therefore, the outer shape of the holder 53 when viewed from above is rectangular or substantially rectangular. On the flange portion 5c, in addition to the aforementioned plurality of threaded holes 53i and the plurality of threaded holes 53k, a plurality of holes 53j are provided. The plurality of holes 53j are holes for positioning the holder 53 relative to the support body 41 by inserting projections (not shown) provided on the support body 41.

[0093] 1-6. Shape of the holding portion of the holder

[0094] Figure 9 It is a diagram for explaining the shape of the holding portion 5a1 of the holder 53 in the first embodiment. In Figure 9 For ease of explanation, the outer shapes of the holding portion 5a1 and the plurality of head chips 54 observed in the Z2 direction are represented by solid lines.

[0095] As Figure 9As shown, when viewed from above in the direction along the Z-axis, the outer edge OE1 of the holding portion 5a1 has a shape corresponding to the arrangement of the head chips 54_1, 54_2, 54_3, and 54_4. That is, the outer edge OE1 has a shape such that when viewed from above, a pair of diagonal corners and their adjacent portions among the four corners of a rectangle are cut into a substantially rectangular shape. Hereinafter, the arrangement of the head chips 54_1, 54_2, 54_3, 54_4 and the shape of the outer edge OE1 of the holding portion 5a1 when viewed from above will be described in detail in sequence.

[0096] As Figure 9 shown, the head chips 54_1, the head chip 54_2, the head chip 54_3, and the head chip 54_4 are arranged in a staggered manner when viewed from above. The head chip 54_1 and the head chip 54_2 are adjacent to each other, the head chip 54_2 and the head chip 54_3 are adjacent to each other, and the head chip 54_3 and the head chip 54_4 are adjacent to each other.

[0097] Specifically, the head chips 54_1, the head chip 54_2, the head chip 54_3, and the head chip 54_4 are arranged side by side in the X1 direction in sequence. However, the head chips 54_1 and 54_3 are arranged at positions deviated in the Y1 direction with respect to the head chips 54_2 and 54_4. Here, the head chips 54_1 and 54_3 are arranged side by side in the X-axis direction in such a manner that their positions along the Y-axis are aligned. Similarly, the head chips 54_2 and 54_4 are arranged side by side in the X-axis direction in such a manner that their positions along the Y-axis are aligned. In addition, the shape of each head chip 54 when viewed from above is a rectangle or a substantially rectangle extending in the Y-axis direction.

[0098] In Figure 9 , when viewed from above, a hypothetical rectangle VS circumscribing the assembly of the head chips 54_1, 54_2, 54_3, and 54_4 arranged as described above is shown by a double-dashed line. The rectangle VS is the smallest rectangle containing the assembly when viewed from above. In addition, in the present embodiment, each of the plurality of head chips 54_1, 54_2, 54_3, and 54_4 is in contact with the hypothetical rectangle VS. In Figure 9 the example shown, the assembly has a bilaterally symmetric shape when viewed from above.

[0099] The outer edge OE1 of the holding portion 5a1 has a portion located inside the rectangle VS and a portion located outside.

[0100] Here, when the four sides of the rectangle VS are defined as the first side E1, the second side E2, the third side E3, and the fourth side E4, the head chip 54_1 is in contact with the first side E1 and the third side E3 when viewed from above. The head chip 54_2 is in contact with the second side E2 when viewed from above. The head chip 54_3 is in contact with the third side E3 when viewed from above. The head chip 54_4 is in contact with the second side E2 and the fourth side E4 when viewed from above.

[0101] Among them, the first side E1 is one of the four sides of the rectangle VS. The second side E2 is the side of the four sides of the rectangle VS that is connected to one end of the first side E1. The third side E3 is the side of the four sides of the rectangle VS that is connected to the other end of the first side E1. The fourth side E4 is the side of the four sides of the rectangle VS other than the first side E1, the second side E2, and the third side E3.

[0102] The first region RE1 surrounded by the first side E1, the second side E2, the head chip 54_1, and the head chip 54_2 when viewed from above is divided into a first inner part RE1a and a first outer part RE1b by the outer edge OE1. The first inner part RE1a is the part of the first region RE1 that is located closer to the inside than the outer edge OE1. The first outer part RE1b is the part of the first region RE1 that is located closer to the outside than the outer edge OE1. In addition, the first region RE1 is a rectangular region surrounded by the first side E1, the second side E2, a straight line along the shorter side of the two shorter sides of the head chip 54_1 that is closer to the head chip 54_2, and a straight line along the longer side of the two longer sides of the head chip 54_2 that is closer to the head chip 54_1 when viewed from above.

[0103] Here, the first side E1 has a first part PA1 that delimits the first region RE1. The first part PA1 is the side of the four sides of the rectangular first region RE1 that belongs to the first side E1. The second side E2 has a second part PA2 that delimits the first region RE1. The second part PA2 is the side of the four sides of the rectangular first region RE1 that belongs to the second side E2. Moreover, when viewed from above, the outer edge OE1 of the holding part 5a1 intersects both the first part PA1 and the second part PA2.

[0104] In addition, when viewed from above, the intersection point IPa of the outer edge OE1 of the holding part 5a1 and the first part PA1 is located closer to the head chip 54_1 than the midpoint MP1 of the first part PA1, and the intersection point IPb of the outer edge OE1 of the holding part 5a1 and the second part PA2 is located closer to the head chip 54_2 than the midpoint MP2 of the second part PA2. In addition, in Figure 9 the example shown, the intersection point IPb is located extremely close to the midpoint MP2, but is in the X1 direction with respect to the midpoint MP2.

[0105] Moreover, the center CP of the first region RE1 is located outside the outer edge OE1 of the holding portion 5a1 when viewed from above. That is, inside the outer edge OE1 of the holding portion 5a1, the center CP of the first region RE1 is not included. Additionally, in Figure 9 the illustrated example, although the center CP is located extremely close to the outer edge OE1, it is located outside the outer edge OE1.

[0106] Similar to the above-described first region RE1, the second region RE2 surrounded by the third side E3, the fourth side E4, the head chip 54_3, and the head chip 54_4 when viewed from above is divided into a second inner portion RE2a and a second outer portion RE2b by the outer edge OE1. The second inner portion RE2a is located closer to the inside than the outer edge OE1. The second outer portion RE2b is located closer to the outside than the outer edge OE1. Additionally, the second region RE2 is a rectangular region surrounded by the third side E3, the fourth side E4, a straight line along the longer side of the two longer sides of the head chip 54_3 that is closer to the head chip 54_4, and a straight line along the shorter side of the two shorter sides of the head chip 54_4 that is closer to the head chip 54_3 when viewed from above.

[0107] 1-7. Shape of the heater

[0108] Figure 10 FIG. is for explaining the shapes of the heater 56 and the heat conducting member 57 in the first embodiment. In Figure 10 , for ease of explanation, the outer shapes of the heater 56 and the plurality of head chips 54 observed in the Z2 direction are represented by solid lines. In addition, in Figure 10 , the outer shape of the flow channel structure 51 or the heat conducting member 57 observed in the Z2 direction is represented by a dashed line.

[0109] As Figure 10 shown, when viewed from above in the direction along the Z axis, the outer edge OE2 of the heater 56 has a shape corresponding to the arrangement of the head chips 54_1, 54_2, 54_3, 54_4. In the present embodiment, as shown in the aforementioned Figure 8 , generally speaking, the outer edge OE2 is the same shape as the outer edge OE1 of the aforementioned holding portion 5a1. That is, it can be said that the outer edge OE2 is a shape along the outer edge OE1. Hereinafter, the shape of the outer edge OE2 of the heater 56 when viewed from above will be described in detail in sequence.

[0110] In Figure 10 , the aforementioned imaginary rectangle VS is shown by a double-dashed line. The outer edge OE2 of the heater 56, similar to the outer edge OE1 of the aforementioned holding portion 5a1, has a portion located inside the rectangle VS and a portion located outside.

[0111] When viewed from above, the first region RE1 is divided into a first inner part RE1c and a first outer part RE1d by the outer edge OE2. The first inner part RE1c is the part of the first region RE1 that is located closer to the inside than the outer edge OE2. The first outer part RE1d is the part of the first region RE1 that is located closer to the outside than the outer edge OE2. In addition, in the present embodiment, since the outer edge OE2 has substantially the same shape as the outer edge OE1 of the holding part 5a1 as described above, the first inner part RE1c is substantially equal to the aforementioned first inner part RE1a, and the first outer part RE1d is substantially equal to the first outer part RE1b.

[0112] Here, when viewed from above, the outer edge OE2 of the heater 56 includes a plurality of head chips 54 and intersects both the first part PA1 and the second part PA2. In addition, when viewed from above, the intersection point IPc of the outer edge OE2 of the heater 56 and the first part PA1 is located closer to the head chip 54_1 than the midpoint MP1 of the first part PA1, and the intersection point IPd of the outer edge OE2 of the heater 56 and the second part PA2 is located closer to the head chip 54_2 than the midpoint MP2 of the second part PA2. In addition, Figure 10 in the example shown, although the intersection point IPd is located extremely close to the midpoint MP2, it is located in the X1 direction with respect to the midpoint MP2.

[0113] The center CP of the first region RE1 is located outside the outer edge OE2 when viewed from above. That is, inside the outer edge OE2 of the heater 56, the center CP of the first region RE1 is not included. In addition, Figure 10 in the example shown, although the center CP is located extremely close to the outer edge OE2, it is located outside the outer edge OE2.

[0114] Similar to the first region RE1 above, when viewed from above, the second region RE2 is divided into a second inner part RE2c and a second outer part RE2d by the outer edge OE2. The second inner part RE2c is located closer to the inside than the outer edge OE2. The second outer part RE2d is located closer to the outside than the outer edge OE2. In addition, in the present embodiment, the second inner part RE2c is substantially equal to the aforementioned second inner part RE2a, and the second outer part RE2d is substantially equal to the second outer part RE2b.

[0115] In contrast, Figure 10The heat-conducting member 57 indicated by a dashed line in [description] not only contains the head chips 54_1, 54_2, 54_3, 54_4 when viewed from above, but also overlaps at least a part of each of the first outer portion RE1d and the second outer portion RE2d. Similarly, although not shown, the heat-conducting member 57 overlaps at least a part of each of the first outer portion RE1b and the second outer portion RE2b shown in Figure 9 when viewed from above.

[0116] Here, the shape of the heat-conducting member 57 when viewed from above is substantially equal to the shape of the flow channel structure 51 when viewed from above. Therefore, when viewed from above, the flow channel structure 51 overlaps at least a part of each of the first outer portion RE1d and the second outer portion RE2d. Similarly, although not shown, the flow channel structure 51 overlaps at least a part of each of the first outer portion RE1b and the second outer portion RE2b shown in Figure 9 when viewed from above.

[0117] 1-8. Heat transfer path from the heater

[0118] Figure 11 FIG. is for explaining the heat transfer paths H1 and H2 from the heater 56 in the first embodiment. In Figure 11 each of the heat transfer paths H1 and H2 is schematically shown by a dashed line.

[0119] As described above, in the support 41, an opening 41a for inserting the outer wall portion 5b is provided. On the other hand, the flange portion 5c has a mounting surface 5c1 in the normal direction of the nozzle surface FN, that is, the Z2 direction. Further, the holder 53 is mounted on the support 41 in a state where the outer wall portion 5b is inserted into the opening 41a with a gap d1 between the outer wall portion 5b and the support 41 and the mounting surface 5c1 is in contact with the support 41.

[0120] The heater 56 heats each of the head chips 54 by transferring heat to each of the head chips 54 through the heat transfer path H1 as described above.

[0121] However, a part of the heat from the heater 56 is transferred to the support 41 via the holder 53. That is, a part of the heat from the heater 56 is not used for heating each of the head chips 54, but escapes to the support 41 via the holder 53. Such heat escape not only causes a decrease in the heating efficiency of each of the head chips 54 by the heater 56, but also causes a deviation in the temperature distribution within or between the head chips 54.

[0122] Therefore, in order to reduce the escape of such heat, the retainer 53 has a structure that increases the thermal resistance of the heat transferred from the heater 56 to the support 41 on the transfer path H2. Specifically, in the retainer 53, as described above, the heated portion 5a11 and the flange portion 5c are connected via the side wall portion 5a12, the connecting portion 5a2, and the outer wall portion 5b.

[0123] The transfer path H2 is a path that transfers heat in the order of the heated portion 5a11, the side wall portion 5a12, the connecting portion 5a2, the outer wall portion 5b, and the flange portion 5c. As described above, the side wall portion 5a12 and the outer wall portion 5b each extend in the direction along the Z axis. In contrast, the connecting portion 5a2 and the flange portion 5c each extend in a direction intersecting the Z axis. Therefore, when the transfer path H2 is observed in the cross section as shown, it bends or curves at least at two places between the heated portion 5a11 and the flange portion 5c. In Figure 11 it, two places where the transfer path H2 bends or curves are shown by the region surrounded by the dashed double-dotted line. Figure 11

[0124] Here, the outer peripheral surface of the side wall portion 5a12 is arranged so as to be spaced apart by an interval d3 from the inner peripheral surface of the outer wall portion 5b over the entire region. Therefore, the transfer of heat from the side wall portion 5a12 to the outer wall portion 5b is not directly carried out between them, but via the connecting portion 5a2. In addition, the flow channel structure 51 is arranged so as to be spaced apart by an interval d2 from the outer wall portion 5b. Therefore, the transfer of heat from the heated portion 5a11 to the outer wall portion 5b does not pass through the flow channel structure 51.

[0125] As described above, the above liquid ejection head 50 includes a plurality of head chips 54, a thermally conductive retainer 53, a thermally conductive flow channel structure 51, and a planar heater 56. Each of the plurality of head chips 54 has a nozzle surface FN provided with nozzles N for ejecting ink as an example of the "liquid". The retainer 53 holds the plurality of head chips 54. In the flow channel structure 51, flow channels for the ink supplied to the plurality of head chips 54 are provided. The heater 56 is disposed between the retainer 53 and the flow channel structure 5, and along a direction parallel to the nozzle surface FN. On this basis, the heater 56 overlaps the plurality of head chips 54 in a top view.

[0126] In the above-described liquid ejection head 50, the heater 56 is disposed between the holder 53 and the flow path structure 51. Therefore, compared with the conventional structure in which the flow path structure 51 is interposed between the heater 56 and the holder 53, the heat from the heater 56 can be effectively transferred to the holder 53 and the flow path structure 51, respectively. As a result, the temperature difference between the holder 53 and the flow path structure 51 can be reduced, and further, the temperature difference between the head chip 54 and the flow path structure 51 can be reduced. In addition, the heater 56 has a planar shape along a direction parallel to the nozzle surface, and on this basis, the heater 56 overlaps with a plurality of head chips 54 in a plan view. Therefore, compared with the structure in which the heater 56 only overlaps with a part of the plurality of head chips 54 in a plan view, the heat from the heater 56 can be effectively transferred to each of the plurality of head chips 54. As a result, the temperature difference between the plurality of head chips 54 can also be reduced. Based on the above, the temperature of the head chip 54 can be managed with high precision by controlling the temperature of the heater 56.

[0127] In the present embodiment, as described above, the holder 53 has a holding portion 5a1 for holding a plurality of head chips 54. The holding portion 5a1 contains a plurality of head chips 54 in a plan view. Therefore, the heat from the heater 56 can be transferred to the plurality of head chips 54 via one holding portion 5a1. As a result, it is not necessary to provide a heater 56 for each head chip 54, and thus, it is easy to provide the heater 56.

[0128] On this basis, each of the plurality of head chips 54 is elongated in the direction along the Y-axis. In addition, the plurality of head chips 54 includes a head chip 54_1 as an example of a "first head chip" and a head chip 54_2 as an example of a "second head chip". The head chip 54_1 and the head chip 54_2 are adjacent to each other. Here, the plurality of head chips being adjacent refers to the positional relationship between the plurality of head chips 54, and structures other than the head chips 54 (for example, the side wall portion 5a12 corresponding to the holder 53 in the present embodiment) may also be interposed between the plurality of head chips 54. In addition, the head chip 54_1 and the head chip 54_3 are arranged at positions that deviate from each other in the direction along the X-axis and are the same in the direction along the Y-axis with the end portion of the head chip 54_2 in the Y1 direction interposed therebetween. However, the head chip 54_1 and the head chip 54_3 are in a positional relationship where they face each other in the direction along the X-axis with a dimension of more than half of the dimension of the head chip 54 in the direction along the Y-axis. Therefore, it can be said that these head chips 54_1 and the head chip 54_3 are also in an adjacent relationship with each other. Moreover, the head chip 54_1 and the head chip 54_2 are arranged so as to deviate from each other in both the direction along the Y-axis and the direction along the X-axis. In addition, when the two directions that intersect each other along the nozzle surface FN are set as the first direction and the second direction, the direction along the Y-axis is an example of the "first direction", and the direction along the X-axis is an example of the "second direction".

[0129] Here, the head chip 54_1 is in contact with the first side E1 and the third side E3 of the imaginary rectangle VS in a top view, and the head chip 54_2 is in contact with the second side E2 in a top view. Moreover, the first region RE1 surrounded by the first side E1, the second side E2, the head chip 54_1, and the head chip 54_2 in a top view includes a first outer portion RE1b located outside the outer edge OE1 of the holding portion 5a1. In addition, the outer edge OE1 is the outer edge of the side wall portion 5a12 in a top view.

[0130] In addition, as described above, the rectangle VS circumscribes the collective body of the plurality of head chips 54 included in the liquid ejection head 50 in a top view. The first side E1 is one of the four sides of the rectangle VS. The second side E2 is the side connected to one end of the first side E1 among the four sides of the rectangle VS. The third side E3 is the side connected to the other end of the first side E1 among the four sides of the rectangle VS.

[0131] In the first outer portion RE1b, neither the holding portion 5a1 nor the head chip 54 exists. Therefore, the existence of such a first outer portion RE1b means reducing the useless portion of the holding portion 5a1 other than the portion to be heated. As a result, it is possible to reduce the escape of heat from the heater 56 to this useless portion, and as a result, the head chip 54 can be effectively heated by the heater 56. In addition, it also has the advantages of being able to achieve a smaller area or power saving of the heater 56.

[0132] As described above, in the retainer 53, a plurality of ink holes 53b are provided, and the plurality of ink holes 53b constitute a flow path for the ink supplied to the plurality of head chips 54. Therefore, from the viewpoint of improving the resistance of the retainer 53 to the ink or effectively transferring the heat from the heater 56 to the ink in the ink holes 53b via the retainer 53, it is preferable that the retainer 53 is made of stainless steel or ceramic.

[0133] In addition, when viewed from above, the first region RE1 includes a first outer portion RE1d that does not overlap with the heater 56. Therefore, a smaller area of the heater 56 can be achieved. Since the head chips 54_1 and 54_2 do not exist in the first outer portion RE1d, useless heat generation of the heater 56 can be reduced. As a result, the head chip 54 can be effectively heated by the heater 56.

[0134] Moreover, as described above, the liquid ejection head 50 further includes a heat conducting member 57 as an example of a "second heat conducting member". The heat conducting member 57 is a member that is disposed between the heater 56 and the flow path structure 51 and has a higher heat conductivity than the flow path structure 51, and is, for example, aluminum. When viewed from above, the heat conducting member 57 and the flow path structure 51 respectively overlap with the first outer portion RE1b. By the presence of the flow path structure 51 in the first outer portion RE1b, the degree of freedom in the distribution of the flow paths in the flow path structure 51 can be increased. In addition, since the heat conducting member 57 is disposed between the heater 56 and the flow path structure 51, the heat from the heater 56 can be spread in the plane direction through the second heat conducting member and then transferred to the flow path structure 51. In particular, even if there is a portion where the flow path structure 51 exists in the first outer portion RE1b, since the heat conducting member 57 also exists in the first outer portion RE1b, the heat from the heater 56 can also be transferred to this portion via the heat conducting member 57. As a result, the deviation in the temperature distribution of the flow path structure 51 caused by the heater 56 can be reduced.

[0135] In addition, as described above, from the viewpoints of improving the resistance of the flow path structure 51 to the ink or effectively transferring the heat from the heater 56 to the ink inside the flow path structure 51, it is preferable that the flow path structure 51 is made of stainless steel or ceramic.

[0136] In addition, in the present embodiment, the plurality of head chips 54 include a head chip 54_3 as an example of the "third head chip" and a head chip 54_4 as an example of the "fourth head chip". The head chip 54_3 and the head chip 54_4 are arranged so as to be offset from each other in both the direction along the Y-axis and the direction along the X-axis.

[0137] Here, when the side other than the first side E1, the second side E2, and the third side E3 among the four sides of the imaginary rectangle VS is defined as the fourth side E4, the head chip 54_3 is in contact with the third side E3 in a top view, and the head chip 54_4 is in contact with the second side E2 and the fourth side E4 in a top view. Moreover, the second region RE2 surrounded by the third side E3, the fourth side E4, the head chip 54_3, and the head chip 54_4 in a top view includes a second outer portion RE2b located outside the outer edge OE1 of the holding portion 5a1.

[0138] In the second outer portion RE2b, similar to the aforementioned first outer portion RE1b, neither the holding portion 5a1 nor the head chip 54 exists. Therefore, the existence of such a second outer portion RE2b means reducing the useless portion of the holding portion 5a1 other than the portion to be heated. As a result, it is possible to reduce the situation where the heat from the heater 56 partially escapes to this useless portion. As a result, the head chip 54 can be effectively heated by the heater 56. In addition, it also has the advantages of being able to achieve miniaturization of the heater 56 or power saving.

[0139] The area of the first outer portion RE1b is preferably at least one-fourth of the area of the first region RE1, more preferably at least one-half and at most nine-tenths of the area of the first region RE1. When the area of the first outer portion RE1b is within such a range, it is possible to preferably reduce the useless portion of the holding portion 5a1 as described above. On the other hand, when the area of the first outer portion RE1b is too small, it indicates a tendency that the power consumption of the heater 56 increases or a deviation in the temperature distribution within each head chip 54 or between the plurality of head chips 54 is likely to occur. On the other hand, when the area of the first outer portion RE1b is too large, it is difficult to ensure the required thickness of the holding portion 5a1. In addition, similar to the relationship between the area of the first outer portion RE1b and the first region RE1, the area of the second outer portion RE2b is also preferably at least one-fourth of the area of the second region RE2.

[0140] In addition, as described above, the heater 56 overlaps with the plurality of head chips 54 when viewed from above. Further, in the above-described first region RE1, when viewed from above, a first outer portion RE1d located outside the outer edge OE2 of the heater 56 is included.

[0141] In the first outer portion RE1d, neither the heater 56 nor the head chip 54 exists. Therefore, the presence of such a first outer portion RE1d means reducing the unnecessary portion of the heater 56. As a result, it is possible to reduce the deviation of the temperature distribution within each head chip 54 or between the plurality of head chips 54 caused by the heat generation of the unnecessary portion. In addition, there is also an advantage that the area of the heater 56 can be reduced or power consumption can be saved.

[0142] Here, when viewed from above, the above-described heat conductive member 57 and the flow path structure 51 respectively overlap with the first outer portion RE1d. Since the flow path structure 51 exists in the first outer portion RE1d, the degree of freedom in arranging the flow paths within the flow path structure 51 can be increased. In addition, even if there is a portion where the flow path structure 51 exists within the first outer portion RE1d, since the heat conductive member 57 also exists in the first outer portion RE1d, heat from the heater 56 can be transferred to this portion via the heat conductive member 57. As a result, it is possible to reduce the deviation of the temperature distribution of the flow path structure 51 caused by the heater 56. In addition, a structure in which a part of the flow path within the flow path structure 51 overlaps with the first outer portion RE1d when viewed from above is particularly useful.

[0143] In addition, as described above, in the above-described second region RE2, when viewed from above, a second outer portion RE2d located outside the outer edge OE2 of the heater 56 is included.

[0144] In the second outer portion RE2d, similar to the above-described first outer portion RE1d, neither the heater 56 nor the head chip 54 exists. Therefore, the presence of such a second outer portion RE2d means reducing the unnecessary portion of the heater 56. As a result, it is possible to reduce the deviation of the temperature distribution within each head chip 54 or between the plurality of head chips 54 caused by the heat generation of the unnecessary portion. In addition, there is also an advantage that the area of the heater 56 can be reduced or power consumption can be saved.

[0145] The area of the first outer portion RE1d is preferably more than one-fourth of the area of the first region RE1, and more preferably more than one-half and less than nine-tenths of the area of the first region RE1. When the area of the first outer portion RE1d is within such a range, unnecessary portions of the heater 56 can be appropriately reduced. In contrast, when the area of the first outer portion RE1d is too small, it indicates a tendency for the power consumption of the heater 56 to increase, or for temperature distribution deviations to easily occur within each head chip 54 or between multiple head chips 54. On the other hand, when the area of the first outer portion RE1d is too large, it becomes difficult for the heat from the heater 56 to be evenly transferred to the portion 5a1 depending on the size of the holding portion 5a1, etc., and even in this regard, it indicates a tendency for temperature distribution deviations to easily occur within each head chip 54 or between multiple head chips 54. Additionally, similar to the relationship between the area of the first outer portion RE1d and the first region RE1, the area of the second outer portion RE2d is also preferably more than one-fourth of the area of the second region RE2.

[0146] Furthermore, as described above, the liquid ejection head 50 is supported on the support body 41. Here, in addition to the holding portion 5a1, the holder 53 has a flange portion 5c that contacts the support body 41 at a position separated from the holding portion 5a1. The heater 56 heats the holding portion 5a1. The holding portion 5a1 has a heat-receiving portion 5a11 that receives heat from the heater 56.

[0147] On this basis, the shortest path of the heat transferred in the holder 53 from the heated portion 5a11 to the flange portion 5c in the transfer path H2 is bent or curved at two or more locations. Here, the bending or curving refers to the following state. For example, when it is bent or curved between the side wall portion 5a12 and the connecting portion 5a2 as in the present embodiment, the length of the side wall portion 5a12 along the transfer path H2 (in other words, the length of the side wall portion 5a12 in the direction along the Z axis) and the length of the connecting portion 5a2 along the transfer path H2 (in other words, the length of the connecting portion 5a2 in the direction along the Y axis) are respectively longer than the thickness in the thickness direction (the direction along the Y axis) of the side wall portion 5a12 and longer than the thickness in the thickness direction (the direction along the Z axis) of the connecting portion 5a2. This is the same even for the bending or curving between the connecting portion 5a2 and the outer wall portion 5b, and is also the same when it is bent or curved by portions other than these. In addition, the "shortest path from the heated portion 5a11 to the flange portion 5c" does not include the path of the heat moving inside the heated portion 5a11 and the flange portion 5c. More specifically, the "shortest path from the heated portion 5a11 to the flange portion 5c" is the portion of the shortest path passing through the inside of the holder 53 from an arbitrary position of the heated portion 5a11 to the contact position of the flange portion 5c with the support 41 that does not include the path of the heat moving inside the heated portion 5a11 and the flange portion 5c. Therefore, compared with a structure in which the shortest path from the heated portion 5a11 to the flange portion 5c is linear, or a structure in which the thickness of the connecting portion 5a2 is increased so that the surface of the connecting portion 5a2 facing the Z1 direction coincides with the first surface F1, the thermal resistance of this shortest path can be increased. As a result, it is difficult for the heat from the heater 56 to dissipate to the support 41 via the flange portion 5c. As a result, the head chip 54 can be effectively heated by the heater 56.

[0148] Here, as described above, the heater 56 is disposed at a position in the direction (Z1 direction) opposite to the normal direction (Z2 direction) of the nozzle surface FN with respect to the holding portion 5a1. Moreover, the holding portion 5a1 also has a side wall portion 5a12 extending in the normal direction (Z2 direction) from the heated portion 5a11. The heated portion 5a11 and the side wall portion 5a12 form a recess 53d which is an example of a "space" for housing the head chip 54. Therefore, it is possible to easily assemble the head chip 54, the holder 53, and the heater 56 in a laminated manner in sequence.

[0149] On this basis, the retainer 53 further has an outer wall portion 5b that is connected to the flange portion 5c and surrounds the side wall portion 5a12 when viewed in the normal direction, and a connecting portion 5a2 that connects the side wall portion 5a12 and the outer wall portion 5b. Moreover, the connecting portion 5a2 extends in a direction intersecting the normal direction, and the side wall portion 5a12 and the outer wall portion 5b respectively extend from the connecting portion 5a2 in a direction opposite to the normal direction.

[0150] In this way, the retainer 53 has a holding portion 5a1 for holding the head chip 54, a flange portion 5c that contacts the support body 41 at a position separated from the holding portion 5a1, an outer wall portion 5b that is connected to the flange portion 5c and surrounds the holding portion 5a1 when viewed in the normal direction of the nozzle surface FN, and a connecting portion 5a2 that connects the holding portion 5a1 and the outer wall portion 5b. Moreover, the holding portion 5a1 projects from the connecting portion 5a2 in a direction opposite to the normal direction, and the outer wall portion 5b extends from the connecting portion 5a2 toward the flange portion 5c in a direction opposite to the normal direction.

[0151] By configuring the retainer 53 in this way, the shortest path in the transfer path H2 from the heat-receiving portion 5a11 to the flange portion 5c has a place where it bends or curves through the connection of the side wall portion 5a12 and the connecting portion 5a2, and a place where it bends or curves through the connection of the outer wall portion 5b and the connecting portion 5a2. That is, in the shortest path in the transfer path H2 from the heat-receiving portion 5a11 to the flange portion 5c, the heat transfer direction in the side wall portion 5a12 and the heat transfer direction in the outer wall portion 5b are in opposite directions.

[0152] In addition, as described above, the outer wall portion 5b surrounds the holding portion 5a1 with a gap therebetween when viewed from above. Therefore, it is possible to easily realize the transfer path H2 that bends or curves at two or more places between the heat-receiving portion 5a11 and the flange portion 5c as described above.

[0153] Moreover, as described above, the flange portion 5c is arranged at a position in a direction opposite to the normal direction of the nozzle surface FN compared to the heat-receiving portion 5a11. Therefore, it is possible to elongate the outer wall portion 5d in the direction along the Z axis and increase the thermal resistance of the transfer path H2.

[0154] In addition, as described above, the heat-receiving portion 5a11 has a first surface F1 and a second surface F2 that face in opposite directions. Here, the first surface F1 is a heat-receiving surface that receives heat from the heater 56. The head chip 54 has a housing 54h provided with an ink flow path. The housing 54h is fixed to the second surface F2 and is made of a material having a lower thermal conductivity than the holder 53. Thus, by making the thermal conductivity of the material constituting the housing 54h lower than that of the holder 53, heat dissipation starting from the ink in the head chip 54 can be reduced. Here, the heat from the heat-receiving portion 5a11 hardly transfers to the housing 54h, and as a result, relatively easily moves along the holder 53 in the direction toward the support 41. Therefore, in the case of using such a housing 54h, it is particularly useful when heat dissipation from the support 41 is difficult as described above.

[0155] Moreover, as described above, the flow path structure body 51 is disposed at a position in a direction opposite to the normal direction of the nozzle surface FN with respect to the holding portion 5a1, and the heater 56 is disposed between the holding portion 5a1 and the flow path structure body 51. Further, the flow path structure body 51 is disposed so as to be spaced apart from the outer wall portion 5b. Therefore, direct heat dissipation from the flow path structure body 51 to the outer wall portion 5b can be reduced.

[0156] In addition, as described above, when viewed in the normal direction of the nozzle surface FN, the outer peripheral surface of the side wall portion 5a12 is disposed so as to be spaced apart from the inner peripheral surface of the outer wall portion 5b over the entire region. Therefore, direct heat dissipation from the side wall portion 5a12 to the outer wall portion 5b can be reduced.

[0157] Moreover, as described above, when viewed in the normal direction of the nozzle surface FN, the flange portion 5c surrounds the outer wall portion 5b over the entire circumference. Therefore, it is possible to prevent the smoke generated along with the ejection of the ink in the head chip 54 from going around the nozzle surface FN to above the support 41 in the vertical direction. On the other hand, although heat from the heater 56 may dissipate from the entire circumference of the flange portion 5c surrounding the outer wall portion 5b to the support 41, as described above, when viewed in the normal direction of the nozzle surface FN, the outer peripheral surface of the side wall portion 5a12 is disposed so as to be spaced apart from the inner peripheral surface of the outer wall portion 5b over the entire region. Therefore, direct heat dissipation from the side wall portion 5a12 to the outer wall portion 5b can be reduced.

[0158] 2. Second Embodiment

[0159] Hereinafter, a second embodiment of the present invention will be described. For elements having the same functions and operations as those in the first embodiment in the following exemplified manner, the reference numerals used in the description of the first embodiment are used, and the detailed description of each is appropriately omitted.

[0160] Figure 12 Exploded perspective view of the liquid ejection head 50A according to the second embodiment. The liquid ejection head 50A is the same as the liquid ejection head 50 of the foregoing first embodiment except for the arrangement of the heater 56 and the heat conducting member 57.

[0161] As Figure 12 shown, in the present embodiment, the side-by-side order of the heater 56 and the heat conducting member 57 in the direction along the Z-axis is opposite to that of the foregoing first embodiment. That is, in the liquid ejection head 50A, in the direction of Z2, they are arranged side by side in the order of the cover 58, the substrate unit 52, the flow channel structure 51, the heater 56, the heat conducting member 57, the holder 53, the four head chips 54, and the fixing plate 55. The heat conducting member 57 of the present embodiment is an example of the "first heat conducting member".

[0162] According to the above second embodiment, the temperature of the head chip 54 can also be managed with high precision in the same manner as in the foregoing first embodiment. In Figure 13 the example shown, the top view shapes of the flow channel structure 51, the heater 56, and the heat conducting member 57 are the same as those of the foregoing first embodiment. That is, when viewed from above, the heat conducting member 57 overlaps with the first outer portion RE1b. However, the top view shape of the heat conducting member 57 is not limited thereto. For example, it may be substantially the same as the top view shape of the heater 56. That is, when viewed from above, the heat conducting member 57 may hardly overlap with the first outer portion RE1b. Here, the heat conducting member 57 hardly overlapping with the first outer portion RE1b includes the case where the portion of the first region RE1 that is outside the outer edge of the heat conducting member 57 does not overlap more than half of the area of the first outer portion RE1b. More preferably, the heat conducting member 57 hardly overlapping with the first outer portion RE1b means that the portion of the first region RE1 that is outside the outer edge of the heat conducting member 57 does not overlap more than three-quarters of the area of the first outer portion RE1b.

[0163] Since the heat conducting member 57 is interposed between the heater 56 and the holder 53, the heat of the heater 56 easily moves in the direction parallel to the nozzle surface FN through the heat conducting member 57, and the deviation of the temperature distribution of the holding portion 5a1 can be reduced.

[0164] 3. Third Embodiment

[0165] Hereinafter, a third embodiment of the present invention will be described. In the following exemplified embodiments, elements having the same functions and effects as those of the first embodiment are denoted by the same reference numerals used in the description of the first embodiment, and their detailed descriptions are appropriately omitted.

[0166] Figure 13 This is a diagram for explaining the heat transfer paths H1 and H2 from the heater 56 in the third embodiment. The liquid ejection head 50B of this embodiment is the same as the liquid ejection head 50 of the first embodiment described above, except that it has a holder 53B instead of the holder 53. The holder 53B is the same as the holder 53, except that it has an outer wall portion 5d instead of the outer wall portion 5b.

[0167] The outer wall portion 5d connects the outer peripheral edge of the connecting portion 5a2 of the bottom portion 5a to the inner peripheral edge of the flange portion 5c. Here, the outer wall portion 5d has a first wall portion 5d1, a first plate portion 5d2, a second wall portion 5d3, a second plate portion 5d4, and a third wall portion 5d5.

[0168] The first wall portion 5d1 is in the shape of a cylinder extending in the Z1 direction from the connecting portion 5a2. The first plate portion 5d2 is in the shape of a plate extending in a direction orthogonal to the Z axis from the first wall portion 5d1 so as to approach the holding portion 5a1. The second wall portion 5d3 is in the shape of a cylinder extending in the Z1 direction from the first plate portion 5d2. The second plate portion 5d4 is in the shape of a plate extending in a direction orthogonal to the Z axis from the second wall portion 5d3 so as to be away from the holding portion 5a1. The third wall portion 5d5 is in the shape of a cylinder extending in the Z1 direction from the second plate portion 5d4.

[0169] Even according to the above third embodiment, the temperature of the head chip 54 can be managed with the same high precision as in the first embodiment described above. In this embodiment, since the bottom portion 5a and the flange portion 5c are connected via the outer wall portion 5d as described above, the heat transfer path H2 from the heater 56 to the support body 41 is bent or curved at least at six places. In Figure 13 , the six places where the heat transfer path H2 is bent or curved are shown by the region surrounded by the double-dashed line. When the number of such bent or curved places of the heat transfer path H2 is four or more, there is an advantage that the thermal resistance of the heat transfer path H2 can be easily increased as compared with the first embodiment described above. In addition, similar to the first embodiment described above, the "shortest path from the heat receiving portion 5a11 to the flange portion 5c" does not include the path of the heat moving inside the heat receiving portion 5a11 and the flange portion 5c.

[0170] 4. Modification

[0171] The above-exemplified embodiments can be variously modified. Hereinafter, specific modification methods applicable to the above-described embodiments are exemplified. Two or more methods arbitrarily selected from the following examples can be appropriately combined within a non-conflicting range.

[0172] 4-1. Modification 1

[0173] In the foregoing manner, the top-view shape of the holding portion 5a1 is a shape different from a rectangle according to the arrangement of the four head chips 54. The top-view shape of the holding portion 5a1 is not limited to the foregoing manner. For example, it may be a rectangle or a substantially rectangle.

[0174] 4-2. Modification Example 2

[0175] Although in the foregoing manner, the heater 56 is arranged between the flow channel structure body 51 and the holder 53, it is not limited thereto. The flow channel structure body 51 may also be interposed between the heater 56 and the holder 53.

[0176] 4-3. Modification Example 3

[0177] Although in the foregoing manner, the structure using one heat conductive member 57 is illustrated, it is not limited to this structure. For example, it may also be a manner obtained by combining the first embodiment and the second embodiment. That is, the heat conductive member 57 may be respectively arranged between the heater 56 and the holder 53, and between the heater 56 and the flow channel structure body 51.

[0178] 4-4. Modification Example 4

[0179] An elastic sheet may also be arranged between the holder 53 and the flow channel structure body 51, both of which are rigid bodies. As such an elastic sheet, an elastomer or the like can be adopted. For example, it is preferably a heat conductive sheet having a higher heat conductivity than the resin material of the housing 54h constituting the head chip 54. As such an elastic heat conductive sheet having a higher heat conductivity than the resin material, it is preferably a material having a heat conductivity of 1.0 W / m·K or more. Specifically, as the heat conductive sheet, it is preferably a propylene-based or silicone-based sheet, or a material in which metal materials such as silicon, stainless steel, aluminum, titanium, and magnesium alloy are dispersed in an elastomer, or a composite material in which an elastic material such as an elastomer contains fillers such as carbon-based materials such as carbon fibers, or ceramic oxides such as silicon dioxide or alumina, or ceramic nitrides such as silicon nitride or boron nitride. By filling the gap between the holder 53 and the flow channel structure body 51 with such an elastic material, even if a manufacturing error occurs in the thickness dimension in the Z-axis direction of the holder 53 or the flow channel structure body 51, the tightness between the heat conductive member 57 or the heater 56 and the heating object such as the holder 53 or the flow channel structure body 51 can be improved, so that the heat from the heater 56 can be effectively transferred to the heating object.

[0180] 4-5. Modification Example 5

[0181] The "outer edge OE2 of the heater 56" in the foregoing embodiment may also be alternatively referred to as the outer edge of the formation region of the heating resistor provided in the heater 56.

[0182] 4-6. Modification Example 6

[0183] Although in the foregoing manner, a structure in which the number of head chips 54 included in the liquid ejection head 50 is four has been illustrated, it is not limited to this structure, and the number may also be two, three, or five or more. Further, although in the foregoing manner, a plurality of head chips 54 are arranged in a staggered manner along the long side direction of the head chip 54, it is not limited to this structure, and a plurality of head chips 54 may also be arranged in a staggered manner along the short side direction of the head chip 54.

[0184] 4-7. Modification Example 7

[0185] When viewed from above, the heater 56 may also not overlap with the first outer portion RE1b. In this structure, miniaturization of the heater 56 can be achieved. Further, since the head chips 54_1, 54_2, and the holding portion 5a1 do not exist in the first outer portion RE1b, by the heater 56 not overlapping with the first outer portion RE1b when viewed from above, useless heat generation of the heater 56 can be further reduced.

[0186] 4-8. Modification Example 8

[0187] Although in the foregoing manner, an example of the serial liquid ejection apparatus 100 in which the support 41 that supports the liquid ejection head 50 reciprocates has been illustrated, the present invention can also be applied to a line-type liquid ejection apparatus in which a plurality of nozzles N are distributed across the entire width of the medium M. That is, the support that supports the liquid ejection head 50 is not limited to the carriage of the serial type, and may also be a structure that supports the liquid ejection head 50 in a line type. In this case, for example, a plurality of liquid ejection heads 50 are arranged side by side in the width direction of the medium M, and the plurality of liquid ejection heads 50 are collectively supported by one support.

[0188] 4-9. Modification Example 9

[0189] The liquid ejection apparatus illustrated in the foregoing manner can be adopted not only in a device dedicated to printing but also in various devices such as a facsimile apparatus or a copying machine. Of course, the use of the liquid ejection apparatus is not limited to printing. For example, a liquid ejection apparatus that ejects a solution of a color material is used as a manufacturing apparatus for forming a color filter of a display device such as a liquid crystal display panel. Further, a liquid ejection apparatus that ejects a solution of a conductive material is used as a manufacturing apparatus for forming wirings or electrodes of a wiring substrate. Further, a liquid ejection apparatus that ejects a solution of an organism-related organic substance is used, for example, as a manufacturing apparatus for manufacturing a biochip.

[0190] Reference Signs

[0191] 5a…Bottom; 5a1…Retention part; 5a11…Heated part; 5a12…Side wall part; 5a2…Connection part; 5b…Outer wall part; 5c…Flange part; 5c1…Mounting surface; 5d…Outer wall part; 5d1…First wall part; 5d2…First plate part; 5d3…Second wall part; 5d4…Second plate part; 5d5…Third wall part; 10…Liquid storage part; 20…Control unit; 30…Delivery mechanism; 40…Moving mechanism; 41…Support body; 41a…Opening; 41b…Threaded hole; 42…Conveyor belt; 50…Liquid ejection head; 50A…Liquid ejection head; 50B…Liquid ejection head; 51…Flow path structure body; 51a…Flow path component; 51b…Connecting pipe; 51c…Wiring hole; 52…Substrate unit; 52a…Circuit board; 52b…Connector; 52c…Support plate; 53…Holder; 53B…Holder; 53a…Recess; 53b…Ink hole; 53c…Wiring hole; 53d…Recess; 53e…Hole; 53f…Hole; 53g…Threaded hole; 53h…Recess; 53i…Threaded hole; 53j…Hole; 53k…Threaded hole; 53l…Flow path pipe; 54…Head chip; 54_1…Head chip (first head chip); 54_2…Head chip (second head chip); 54_3…Head chip (third head chip); 54_4…Head chip (fourth head chip); 54a…Flow path substrate; 54b…Pressure chamber substrate; 54c…Nozzle plate; 54d…Vibration absorber; 54e…Vibration plate; 54f…Piezoelectric element; 54g…Protection plate; 54h…Outer shell; 54i…Wiring substrate; 54j…Driver circuit; 54k…Frame; 55…Fixing plate; 55a…Opening part; 56…Heater; 56a…Hole; 56b…Hole; 57…Thermal conduction component; 57a…Hole; 57b…Wiring hole; 57c…Hole; 58…Cover; 58a…Through hole; 58b…Opening part; 100…Liquid ejection device; C…Pressure chamber; CP…Center; D…Drive signal; DM…Delivery direction; E1…First side; E2…Second side; E3…Third side; E4…Fourth side; F1…First surface; F2…Second surface; FN…Nozzle surface; H1…Transfer path; H2…Transfer path (shortest path); IO…Inlet; IPa…Intersection point; IPb…Intersection point; IPc…Intersection point; IPd…Intersection point; L1…First column; L2…Second column; M…Medium; MP1…Midpoint; MP2…Midpoint; N…Nozzle; Na…Communication flow path; OE1…Outer edge; OE2…Outer edge; PA1…First part; PA2…Second part; R…Liquid reservoir; R1…Space; R2…Space; RE1…First region; RE1a…First inner part; RE1b…First outer part; RE1c…First inner part; RE1d…First outer part; RE2…Second region; RE2a…Second inner part; RE2b…Second outer part; RE2c…Second inner part; RE2d…Second outer part; Ra…Supply flow path; S…Control signal; VS…Rectangle.

Claims

1. A liquid ejection head, characterized in that, Comprising: A plurality of head chips, each of the head chips having a nozzle plate, the nozzle plate having a nozzle surface, and a plurality of nozzles for ejecting liquid being provided on the nozzle surface; A heat-conductive holder that holds the plurality of head chips; A planar heater that is disposed at a position where the holder is interposed between the heater and the plurality of head chips and extends in a direction parallel to the nozzle surface, When two directions intersecting each other along the nozzle surface are defined as a first direction and a second direction, Each of the plurality of head chips is elongated along the first direction, The plurality of head chips includes a first head chip and a second head chip, The first head chip and the second head chip are arranged so as to be offset from each other in both the first direction and the second direction, When one of the four sides of a hypothetical rectangle circumscribing the collective body of the plurality of head chips in a top view is defined as a first side, a side connected to one end of the first side is defined as a second side, and a side connected to the other end of the first side is defined as a third side, The first head chip abuts on the first side and the third side in the top view, The second head chip abuts on the second side in the top view, The heater overlaps the plurality of head chips in the top view, A first region surrounded by the first side, the second side, the first head chip, and the second head chip in the top view includes a first outer portion located outside the outer edge of the heater.

2. The liquid ejection head according to claim 1, wherein The first side has a first portion that defines the first region, The second side has a second portion that defines the first region, In the top view, the outer edge of the heater encloses the plurality of head chips and intersects both the first portion and the second portion.

3. The liquid ejection head according to claim 2, wherein In the top view, the intersection of the outer edge of the heater and the first portion is located closer to the first head chip than the midpoint of the first portion, and the intersection of the outer edge of the heater and the second portion is located closer to the second head chip than the midpoint of the second portion.

4. The liquid ejection head according to any one of claims 1 to 3, wherein The outer shape of the holder in the top view is rectangular or substantially rectangular.

5. The liquid ejection head according to claim 1, wherein It further includes a fixing plate that fixes the plurality of head chips relative to the holder, The fixing plate has an opening for exposing the nozzle surface, The outer shape of the fixing plate in the top view is rectangular or substantially rectangular.

6. The liquid ejection head according to claim 1, wherein It further includes a first heat-conductive member that is disposed between the holder and the heater and has a higher thermal conductivity than the holder, When viewed from above, the outer shape of the first heat conductive member is substantially the same as the outer shape of the heater.

7. The liquid ejection head according to claim 6, wherein in the retainer, a flow path for the liquid supplied to the plurality of head chips is provided, the retainer is made of metal or ceramic.

8. The liquid ejection head according to claim 1, wherein a flow path structure body is further provided, and a flow path for the liquid supplied to the plurality of head chips is provided in the flow path structure body, the heater is disposed between the flow path structure body and the retainer.

9. The liquid ejection head according to claim 8, wherein a second heat conductive member is further provided, the second heat conductive member is disposed between the heater and the flow path structure body, and the heat conductivity is higher than that of the flow path structure body, when viewed from above, the second heat conductive member and the flow path structure body respectively overlap with the first outer portion.

10. The liquid ejection head according to claim 9, wherein the flow path structure body is made of stainless steel or ceramic.

11. The liquid ejection head according to claim 1, wherein the plurality of head chips include a third head chip and a fourth head chip, the third head chip and the fourth head chip are arranged so as to be offset from each other in both the first direction and the second direction, when the side other than the first side, the second side, and the third side among the four sides of the imaginary rectangle is defined as the fourth side, the third head chip is in contact with the third side when viewed from above, the fourth head chip is in contact with the second side and the fourth side when viewed from above, a second region surrounded by the third side, the fourth side, the third head chip, and the fourth head chip when viewed from above includes a second outer portion located outside the outer edge of the heater.

12. The liquid ejection head according to claim 1, wherein the center of the first region is located outside the outer edge of the heater.

13. The liquid ejection head according to claim 1, wherein the area of the first outer portion is one-fourth or more of the area of the first region.

14. A liquid ejection device, characterized in that, Comprising: the liquid ejection head according to any one of claims 1 to 13; a liquid storage portion that stores the liquid supplied to the liquid ejection head.

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