Liquid ejection head and liquid ejection device

Abstract

The present invention provides a liquid ejection head and a liquid ejection device that can supply a sufficiently heated liquid to a head chip through a heater and can simplify the structure without heating the head chip through a holder made of a material having a high thermal conductivity. The liquid ejection head includes: a plurality of head chips (10) having a nozzle plate with a plurality of nozzles for ejecting liquid in a first direction (+Z) and a housing (13) formed with one or more first flow paths communicating with at least a part of the plurality of nozzles; a holder (40) that fixes the plurality of head chips (10), is configured to include metal or ceramic, and has a plurality of second flow paths (50) communicating with at least one of the plurality of first flow paths; and a heater (70) that heats the holder (40).

Description

Technical Field

[0001] The present invention relates to a liquid ejection head that ejects a liquid from a nozzle and a liquid ejection device, and more particularly to an inkjet recording head and an inkjet recording device that eject ink as a liquid. Background Art

[0002] A liquid ejection device represented by an inkjet printer or a plotter or the like includes a liquid ejection head that can eject a liquid such as ink stored in a cartridge or a tank as droplets.

[0003] As the liquid ejection head, a head chip provided with a nozzle for ejecting a liquid and a holder for holding a plurality of head chips are provided.

[0004] In the liquid ejected from such a liquid ejection head, there is an appropriate viscosity corresponding to the type of the liquid. Since the viscosity of the liquid has a correlation with the temperature, it has the characteristic that the viscosity becomes higher as the temperature becomes lower and the viscosity becomes lower as the temperature becomes higher. Therefore, when a liquid ejection head designed to have a viscosity suitable for normal use is placed in a low-temperature environment, or when a liquid with a high viscosity is ejected, it is necessary to heat the liquid. A structure in which a heater is provided in the liquid ejection head to heat the liquid has been disclosed (for example, refer to Patent Document 1 and Patent Document 2).

[0005] Specifically, Patent Document 1 discloses a structure in which a first heater is provided on a frame that holds a plurality of flow path modules, a second heater is provided on a second tank that supplies a liquid, and a connecting portion that connects the flow path module and the second tank is provided.

[0006] In addition, Patent Document 2 discloses a structure in which heaters for heating the outer casings of the head chips are provided.

[0007] However, in Patent Document 1, since the periphery of the connecting portion is in contact with the outside, when the ink in the second tank heated by the second heater is supplied to the flow path module via the connecting portion, heat is dissipated from the connecting portion and the temperature of the ink supplied to the flow path module is lowered. Although in order to compensate for this, the flow path module is heated by the first heater via the frame and the nozzle plate, since the frame and the nozzle plate are in contact with the outside air, the heat of the first heater is also dissipated from here, and the ink in the flow path module may not be sufficiently heated.

[0008] In addition, although a structure in which heating inside the head chip is implemented by providing heaters corresponding to respective head chips as in Patent Document 2 can be considered, there is a problem that the structure becomes complicated by providing a heater near the nozzle. Specifically, the closer the heater is disposed to the nozzle, the longer the length of the wiring connected to the heater. In addition, wiring layout needs to be implemented, so the structure becomes complicated.

[0009] Furthermore, such a problem is not limited to an inkjet recording head that ejects ink, and the same problem also exists in a liquid ejection head that ejects a liquid other than ink.

[0010] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2016-97568

[0011] Patent Document 2: Japanese Unexamined Patent Application Publication No. 2019-155839 Summary of the Invention

[0012] In view of such circumstances, an object of the present invention is to provide a liquid ejection head and a liquid ejection device that can supply a liquid sufficiently heated by a heater to a head chip and can simplify the structure without heating the head chip by a holder made of a material having a high thermal conductivity.

[0013] A liquid ejection head according to an aspect of the present invention for solving the above problems is characterized by including: a plurality of head chips each having a nozzle plate and a housing, the nozzle plate having a plurality of nozzles for ejecting a liquid in a first direction, and the housing forming one or more first flow paths communicating with at least a part of the plurality of nozzles; a holder that fixes the plurality of head chips and is configured to include metal or ceramic and has a plurality of second flow paths communicating with at least one of the plurality of first flow paths; and a heater that heats the holder.

[0014] In addition, another aspect of the present embodiment is a liquid ejection device characterized by including: the liquid ejection head according to the above aspect; and a holding member that holds the liquid ejection head and is made of metal, and a part of the holding member is disposed so as to be separated from the heater by the head outer wall.

[0015] In addition, another aspect of the present invention is a liquid ejection device characterized by including: the liquid ejection head according to the above aspect; and a holding member that holds the liquid ejection head and is made of resin, and a part of the holding member is disposed so as to be separated from the heater by the head outer wall.

[0016] In addition, another aspect of the present invention is a liquid ejection device, characterized by comprising: the liquid ejection head of the above aspect; a holding member that holds the liquid ejection head and is made of resin, and a part of the holding member is arranged so as to be separated from the holder by the heater.

[0017] In addition, another aspect of the present invention is a liquid ejection device, characterized by comprising: the liquid ejection head of the above aspect; a control device that controls the heater.

[0018] In addition, another aspect of the present invention is a liquid ejection device, characterized by comprising: the liquid ejection head of the above aspect; a liquid container that stores the liquid ejected from the liquid ejection head. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 Exploded perspective view of the recording head according to Embodiment 1.

[0020] Figure 2 Top view of the head chip according to Embodiment 1.

[0021] Figure 3 Cross-sectional view of the head chip according to Embodiment 1.

[0022] Figure 4 Top view of the recording head according to Embodiment 1.

[0023] Figure 5 Cross-sectional view of the recording head according to Embodiment 1.

[0024] Figure 6 Cross-sectional view of the recording head according to Embodiment 1.

[0025] Figure 7 Perspective view of the holder and the heater according to Embodiment 1.

[0026] Figure 8 Side view of the holder and the heater according to Embodiment 1.

[0027] Figure 9 Side view of the holder and the heater according to Embodiment 1.

[0028] Figure 10 Side view of the holder and the heater according to Embodiment 1.

[0029] Figure 11 Top view showing a modified example of the holder and the heater according to Embodiment 1.

[0030] Figure 12A diagram showing the schematic structure of the recording apparatus according to Embodiment 1.

[0031] Figure 13 A cross-sectional view of the main part of the recording head and the holding member according to Embodiment 1.

[0032] Figure 14 A cross-sectional view of the main part of the recording head and the holding member according to Embodiment 1.

[0033] Figure 15 A cross-sectional view of the recording head according to Embodiment 2.

[0034] Figure 16 A perspective view of the holder and the heater according to Embodiment 2.

[0035] Figure 17 A cross-sectional view of the recording head according to Embodiment 2.

[0036] Figure 18 A cross-sectional view showing a modified example of the recording head according to Embodiment 2.

[0037] Figure 19 A perspective view showing a modified example of the holder and the heater according to Embodiment 2.

[0038] Figure 20 A bottom view of the recording head according to other embodiments.

[0039] Figure 21 A bottom view of the recording head according to other embodiments. Detailed Embodiments

[0040] Hereinafter, the present invention will be described in detail based on the embodiments. However, the following description represents one aspect of the present invention, and arbitrary changes can be made within the scope of the present invention. Components marked with the same reference numerals in the respective drawings represent the same components, and the description is appropriately omitted. In addition, in each drawing, X, Y, and Z represent three mutually orthogonal spatial axes. In this specification, the directions along these axes are defined as the X direction, the Y direction, and the Z direction. The direction toward the arrow mark in each drawing is defined as the positive (+) direction, and the opposite direction of the arrow mark is defined as the negative (-) direction for description. In addition, the Z direction represents the vertical direction, the +Z direction represents vertically downward, and the -Z direction represents vertically upward. Moreover, for the three spatial axes where the positive and negative directions are not limited, they are defined as ±X direction, ±Y direction, and ±Z direction for description.

[0041] Embodiment 1

[0042] Figure 1Exploded perspective view of an inkjet recording head 1 as an example of the "liquid ejection head" according to Embodiment 1 of the present invention.

[0043] As shown in the figure, an inkjet recording head 1 (hereinafter, also simply referred to as the recording head 1) as an example of the "liquid ejection head" of the present embodiment has a plurality of head chips 10 and a holder 40 that holds the plurality of head chips 10. In the present embodiment, on one holder 40, four head chips 10 are arranged and configured in the +Y direction orthogonal to the +Z direction. In the present embodiment, the +Z direction is an example of the "first direction", and the +Y direction is an example of the "third direction". In addition, the number of head chips 10 held on the holder 40 is not limited to four, and may be any number of two or more. Furthermore, the configuration of the plurality of head chips 10 is not limited to this.

[0044] Here, refer to Figures 2 to 3 , and an example of the head chip 10 will be described. In addition, Figure 2 is a top view of the head chip 10 as viewed along the +Z direction, Figure 3 is Figure 2 a cross-sectional view taken along line A-A' of

[0045] As Figure 2 and Figure 3 shown, the head chip 10 includes a nozzle plate 12 provided with a plurality of nozzles 11 for ejecting ink toward the +Z direction, and a housing 13 in which an inlet 32 and an introduction liquid chamber 31, which are examples of the "first flow path" communicating with the plurality of nozzles 11, are formed. In addition, the head chip 10 of the present embodiment further includes a communication plate 14, a pressure chamber forming substrate 15, a vibration plate 16, a plastic substrate 17, a piezoelectric actuator 18, and the like. A plurality of structural components constituting these head chips 10 are laminated and joined by an adhesive or the like to be unitized.

[0046] The pressure chamber forming substrate 15 of the present embodiment has a plurality of pressure chambers 19 respectively communicating with a plurality of nozzles 11 formed on the nozzle plate 12. A plurality of piezoelectric actuators 18 are provided corresponding to the respective pressure chambers 19. The piezoelectric actuator 18 is an energy generating element that causes a pressure change in the ink in the corresponding pressure chamber 19, that is, generates the energy required to eject the ink from the nozzle 11 communicating with the pressure chamber 19, and is also a pressure generating element. A diaphragm 16 is provided between the pressure chamber 19 and the piezoelectric actuator 18, and the opening on the -Z direction side of the pressure chamber 19 is sealed by the diaphragm 16, thereby partitioning a part of the pressure chamber 19. In addition, the pressure chamber forming substrate 15 and the diaphragm 16 may be integrally formed. Moreover, the piezoelectric actuators 18 are respectively laminated on the regions of the diaphragm 16 corresponding to the respective pressure chambers 19. The piezoelectric actuator 18 of the present embodiment has a first electrode 20, a piezoelectric body layer 21, and a second electrode 22 laminated in sequence on the diaphragm 16. When an electric field corresponding to the potential difference between the two electrodes is applied between the first electrode 20 and the second electrode 22, the piezoelectric actuator 18 configured in this way flexes and deforms.

[0047] In addition, a flexible wiring substrate 23 is connected to the piezoelectric actuator 18. In the present embodiment, each electrode of the piezoelectric actuator 18 and the wiring substrate 23 are connected via a lead wiring 24 led out from the piezoelectric actuator 18 to the diaphragm 16. A drive circuit 25 such as a circuit board or a semiconductor integrated circuit (IC) having switching elements such as transmission gates for driving the piezoelectric actuator 18 is mounted on the wiring substrate 23. Such a wiring substrate 23 is led out in the -Z direction of the pressure chamber forming substrate 15.

[0048] On the +Z direction side surface of the pressure chamber forming substrate 15, a communication plate 14 having a larger area than the pressure chamber forming substrate 15 when viewed from above in the +Z direction is joined. On the communication plate 14 of the present embodiment, a nozzle communication port 26 that communicates the pressure chamber 19 and the nozzle 11, a common liquid chamber 27 provided in common for each pressure chamber 19, and an independent communication port 28 that communicates the common liquid chamber 27 and the pressure chamber 19 are formed. The common liquid chamber 27 is a space extending along the ±X direction, which is the direction in which the nozzles 11 are arranged. In the present embodiment, two common liquid chambers 27 are formed corresponding to the columns of two rows of nozzles 11 provided in the nozzle plate 12 respectively. A plurality of independent communication ports 28 are formed along the ±X direction, which is the nozzle row direction, corresponding to the respective pressure chambers 19. The independent communication port 28 communicates with the end portion on the opposite side of the portion of the pressure chamber 19 that communicates with the nozzle communication port 26.

[0049] At approximately the central portion of the surface on the +Z direction side of the connection plate 14, a nozzle plate 12 formed with a plurality of nozzles 11 is joined. The nozzle plate 12 in the present embodiment is a plate material having a smaller outer shape compared to the connection plate 14 when viewed in a plan view along the -Z direction. The nozzle plate 12 is joined by an adhesive or the like in a state where the nozzle communication ports 26 and the plurality of nozzles 11 are respectively in communication, at a position on the surface of the connection plate 14 on the +Z direction side that deviates from the opening of the common liquid chamber 27 and in the region where the nozzle communication ports 26 open. On the nozzle plate 12 in the present embodiment, a total of two nozzle rows (not shown) formed by arranging a plurality of nozzles 11 in the +X direction as the aforementioned nozzle row direction are formed. The two nozzle rows are arranged in the +Y direction.

[0050] In addition, on the surface of the connection plate 14 on the +Z direction side, a plastic substrate 17 is joined at a position deviating from the nozzle plate 12. The plastic substrate 17 seals the opening of the common liquid chamber 27 on the surface of the connection plate 14 on the +Z direction side in a state of being positioned and joined thereto.

[0051] In the present embodiment, the plastic substrate 17 includes a sealing film 17a made of a flexible film such as resin and a fixing substrate 17b made of a hard material such as metal like stainless steel. Since the region of the fixing substrate 17b facing the common liquid chamber 27 becomes a fixing substrate opening portion 17c that is completely removed in the thickness direction, one surface of the common liquid chamber 27 becomes a flexible portion, that is, a plastic portion 17d that is sealed only by the flexible sealing film 17a. By flexibly deforming the plastic portion 17d, it has the function of alleviating pressure fluctuations in the ink flow path, particularly in the common liquid chamber 27.

[0052] In addition, on the -Z direction of the pressure chamber forming substrate 15, a protective substrate 29 having substantially the same size as the pressure chamber forming substrate 15 is joined. The protective substrate 29 has a holding portion 30 that serves as a space for protecting the piezoelectric actuator 18.

[0053] The pressure chamber forming substrate 15, the protective substrate 29, and the communication plate 14 are fixed to the housing 13. Inside the housing 13, introduction liquid chambers 31 that communicate with the common liquid chamber 27 of the communication plate 14 are formed on both sides with the pressure chamber forming substrate 15 interposed therebetween. Further, in the surface on the -Z direction side of the housing 13, introduction ports 32 that communicate with the respective introduction liquid chambers 31 are formed. The introduction ports 32 communicate with a second flow path 50 provided in a holder 40, the details of which will be described later. Accordingly, the ink delivered from the holder 40 is introduced into the introduction ports 32, the introduction liquid chambers 31, and the common liquid chamber 27, and is supplied from the common liquid chamber 27 to the respective pressure chambers 19 through the independent communication ports 28. In the present embodiment, the introduction ports 32 and the introduction liquid chambers 31 provided in the housing 13 correspond to the "first flow path" of the present invention. Further, in the protective substrate 29 and the housing 13, a wiring insertion hole 33 through which the wiring substrate 23 is inserted is provided. The wiring substrate 23 led out from the pressure chamber forming substrate 15 in the -Z direction is inserted through the wiring insertion holes 33 of the protective substrate 29 and the housing 13, and is led out to the -Z direction side of the housing 13.

[0054] In the present embodiment, such a housing 13 is made of resin. As the resin constituting the housing 13, for example, a thermoplastic resin or a thermosetting resin may be used. As the thermoplastic resin, for example, polyphenylene ether resin (PPE), modified polyphenylene ether resin (m-PPE), polyethylene resin (PE), polystyrene resin (PS), polyamide resin (PA), polyphenylene sulfide (PPS), polypropylene (PP), liquid crystal polymer (LCP), acrylonitrile-butadiene-styrene copolymer (ABS) resin, vinyl chloride-vinyl acetate copolymer resin, polyvinyl chloride resin, or the like, or a mixture thereof can be cited. Further, as the thermosetting resin, phenolic resins such as bakelite, epoxy resins such as epoxy glass, polyurethane resins, melamine resins, ester resins, or the like can be cited. Additionally, preferably, in the housing 13, a thermosetting resin having excellent temperature stability, liquid resistance, and high rigidity is used. In this way, compared with metals or the like, by making the housing 13 of resin, the heat conductivity can be reduced. Accordingly, it is possible to suppress a decrease in the temperature of the ink flowing in the first flow path, that is, the introduction ports 32 and the introduction liquid chambers 31 provided in the housing 13, and the ink with the temperature decrease suppressed can be guided to the nozzle 11. Further, compared with the case where the housing 13 is made of metal or ceramic, the cost can be reduced by making the housing 13 of resin. In particular, since a plurality of head chips 10 are provided in one recording head 1, by making the housing 13 of resin, the number of metal parts or ceramic parts used in the head chips 10 can be reduced, and thus the cost can be significantly reduced. Of course, the housing 13 may be made of a material other than resin, for example, metal or ceramic.

[0055] Moreover, in the head chip 10 with the above structure, when the flow path from the liquid introduction chamber 31 through the common liquid chamber 27 and the pressure chamber 19 to the nozzle 11 is filled with ink, by driving the piezoelectric actuator 18, a pressure change is generated in the ink within the pressure chamber 19, and due to this pressure change, the ink is ejected from a predetermined nozzle 11.

[0056] In addition, the housing 13 of the head chip 10 of the present embodiment has two "first flow paths", the nozzle plate 12 of the present embodiment has a plurality of nozzles 11 forming two nozzle rows, and moreover, the plurality of nozzles 11 forming one nozzle row communicate with one "first flow path", and the plurality of nozzles 11 forming the other nozzle row communicate with the other "first flow path", but it is not limited to this manner. The housing 13 of the head chip 10 only needs to have one or more "first flow paths", and in addition, the "first flow path" only needs to communicate with at least a part of the plurality of nozzles 11 provided on the nozzle plate 12. That the "first flow path" communicates with at least a part of the plurality of nozzles 11 provided on the nozzle plate 12 means that it may include a structure in which the "first flow path" communicates with all the nozzles of the plurality of nozzles 11 provided in the nozzle plate 12, or a structure in which it communicates with two or more of the plurality of nozzles 11 provided in the nozzle plate 12.

[0057] As Figure 1 shown, in the present embodiment, four head chips 10 are held on the holder 40 at a predetermined interval along the +Y direction in a posture where the nozzle row direction is along the +X direction and with the positions in the +X direction being the same. In addition, the +Y direction is an example of the "third direction".

[0058] In the holder 40, a plurality of (four in the present embodiment) head chips 10 are fixed on the surface in the +Z direction, and inside it, a second flow path 50 communicating with the introduction port 32 and the liquid introduction chamber 31, which are the "first flow paths" provided in the housing 13 of the head chip 10, is provided.

[0059] Here, with further reference to Figures 4 to 10 , the holder 40 will be described. In addition, Figure 4 is a top view of the recording head 1. Figure 5 is Figure 4 a cross-sectional view taken along the line B - B' of Figure 6 is Figure 4 a cross-sectional view taken along the line C - C' of Figure 7 is a perspective view of the holder 40 and the heater 70, and is a view showing only two second flow paths 50 with respect to one head chip 10 by a dashed line. Figures 8 to 10 is a side view of the holder 40 and the heater 70.

[0060] As shown in the figure, in the retainer 40 of the present embodiment, the first member 41, the second member 42, and the third member 43 are sequentially laminated in the +Z direction and joined to each other by an adhesive or the like. In addition, the fixing method of each member constituting the retainer 40 is not limited to joining by an adhesive, and may be set to be fastened by screws or bolts. In addition, it may be set that a seal or the like for suppressing the leakage of ink from the second flow path 50 is provided between the respective members constituting the retainer 40.

[0061] The retainer 40 is configured to include metal or ceramic. Here, the retainer 40 being configured to include metal or ceramic means a case where at least one of the plurality of members constituting the retainer 40 is made of metal or ceramic. That is, as long as at least one of the plurality of members constituting the retainer 40 is made of metal or ceramic, the other members may be made of materials other than metal and ceramic, for example, may be made of resin or the like.

[0062] In addition, the retainer 40 being configured to include metal or ceramic means a case where at least a part of the members constituting the retainer is made of metal or ceramic. That is, it includes a case where all or a part of one of the plurality of members constituting the retainer 40 is made of metal or ceramic. That is, as long as at least a part of one of the plurality of members constituting the retainer 40 is made of metal or ceramic, the other parts may be made of materials other than metal and ceramic, for example, may be made of resin or the like. In addition, a member made of metal or ceramic and other materials such as resin can be integrally manufactured by insert molding or the like.

[0063] In addition, the retainer 40 being configured to include metal or ceramic means a case where 80% or more of the volume of the retainer 40 is made of metal or ceramic.

[0064] Moreover, the retainer 40 being configured to include metal or ceramic means a case where the portion from at least a part of the outer peripheral wall 46 provided with a heater 70, the details of which will be described later, to at least a part of the inner wall surface forming the second flow path 50 is formed of metal or ceramic. Thus, by forming the retainer 40 from at least a part of the outer peripheral wall 46 provided with the heater 70 to at least a part of the inner wall surface of the second flow path 50 of metal or ceramic, the heat of the heater 70 can be effectively transferred to the ink flowing in the second flow path 50.

[0065] In the present embodiment, the first member 41, the second member 42, and the third member 43 that constitute the retainer 40 are all formed of the same metal or ceramic. Here, as the metal constituting the retainer 40, materials with high liquid resistance can be cited. For example, stainless steel, titanium, etc. can be cited. In addition, as the ceramic constituting the retainer 40, for example, ceramics with good thermal conductivity such as aluminum nitride, silicon carbide, alumina, and silicon nitride can be cited. Additionally, regarding the thermal conductivity of ceramics, the thermal conductivity of aluminum nitride is 150 W / m·k, that of silicon carbide is 60 W / m·k, that of alumina is 32 W / m·k, and that of silicon nitride is 20 W / m·k. Therefore, compared with metals, by forming the retainer 40 from the above-mentioned ceramics, the thermal conductivity can be increased, and it is easy to transfer the heat of the heater 70, the details of which will be described later, to the ink in the second flow path 50. In addition, although the thermal conductivity becomes lower by forming the retainer 40 from a metal compared with ceramics, compared with resins, the thermal conductivity can be increased, processing is relatively easy, and the rigidity can be increased. Further, it is preferable that the first member 41, the second member 42, and the third member 43 use materials with equal linear expansion coefficients. In this way, by using the same material for the first member 41, the second member 42, and the third member 43, it is possible to suppress damage such as peeling or cracking caused by warping due to differences in linear expansion coefficients. In particular, since the retainer 40 is heated by the heater 70, the details of which will be described later, it is easy to cause damage such as peeling or cracking due to warping due to differences in the linear expansion coefficients of the respective members constituting the retainer 40. By using the same material for the respective members constituting the retainer 40, even when the retainer 40 is heated by the heater 70, it is possible to suppress damage such as peeling or cracking caused by warping due to differences in linear expansion coefficients.

[0066] In addition, the first member 41 and the second member 42 have substantially the same outer shape when viewed from above in the +Z direction. In the present embodiment, the first member 41 and the second member 42 have a substantially rectangular shape when viewed from above in the +Z direction. In addition, the shape of the first member 41 and the second member 42 when viewed from above in the +Z direction is not limited to a rectangular shape, and it may be a polygonal shape, a circular shape, an elliptical shape, or the like.

[0067] In addition, when observing from above in the +Z direction, the +Z direction side of the third component 43 is formed with an outer shape of substantially the same size as that of the first component 41 and the second component 42. Further, on the +Z direction side of the third component 43, there are provided convex portions 43a that protrude outward, i.e., in the ±X and ±Y directions, compared with the first component 41 and the second component 42 when observing from above in the +Z direction. In this way, by providing the convex portions 43a, the heater 70, the details of which will be described later, can be brought into contact with the surface on the -Z direction side of the convex portions 43a for positioning, and thus, the positioning of the heater 70 with respect to the holder 40 in the ±Z directions can be easily implemented.

[0068] Here, in the present embodiment, the outer wall having the surface on the -Z direction, which is the direction opposite to the +Z direction, of the holder 40 is referred to as the upper wall 44, the outer wall having the surface on the "+Z direction", which is the "first direction", is referred to as the lower wall 45, and the outer wall having the side surfaces connecting the upper wall 44 and the lower wall 45, that is, the side surfaces along the ±Z directions, that is, the side surfaces including any one of the ±X and ±Y directions and the ±Z directions are referred to as the outer peripheral wall 46. In addition, the -Z direction is an example of the "second direction".

[0069] The lower wall 45 of the third component 43 has a plurality of recesses 47 for accommodating the respective head chips 10. The recesses 47 are formed such that they open to the lower wall 45, that is, the surface on the +Z direction of the holder 40 and face the -Z direction to have substantially the same opening area. Further, in the present embodiment, since the recesses 47 for accommodating the respective head chips 10 are provided, a partition wall 48 formed of a part of the third component 43 is provided between the head chips 10 adjacent to each other in the +Y direction. In this way, by providing the recesses 47 for accommodating the respective head chips 10 in the holder 40, the rigidity of the holder 40 can be improved, and the deviation of the ejection positions of the ink droplets ejected from the respective head chips 10 can be suppressed. Each head chip 10 is provided with a gap from the inner peripheral surface of the respective recess 47 of the holder 40 and is fixed to the bottom surface of the respective recess 47 using an adhesive or the like. In addition, the bottom surface of the recess 47 refers to the surface on the -Z direction side of the recess 47. Further, although the details will be described later, a common fixing plate 60 is fixed to the nozzle plate 12 side of the plurality of head chips 10. A part of the fixing plate 60 is fixed to the partition wall 48 between the adjacent recesses 47. In this way, by fixing the fixing plate 60 using the partition wall 48, the rigidity of the fixing plate 60 can be further improved, and the relative position deviation of the plurality of head chips 10 caused by the deformation of the fixing plate 60 can be suppressed. Of course, the recesses 47 for accommodating the head chips 10 in the holder 40 are not limited thereto, and two or more head chips 10 may be accommodated in one recess 47.

[0070] In addition, a fixing plate 60 is fixed to the lower wall 45 of the retainer 40 including the partition wall 48. The fixing plate 60 is made of a metal such as stainless steel or titanium. A plurality of exposure openings 61 for exposing the nozzle plate 12 of the head chip 10 are provided on the fixing plate 60. The exposure opening 61 of the present embodiment has a size slightly larger than the nozzle plate 12 and smaller than the outer shape of the plastic substrate 17. Therefore, the exposure openings 61 are independently provided for each nozzle plate 12. In addition, the fixing plate 60 is also joined to the plastic substrate 17 of the head chip 10. Of course, the exposure openings 61 may be provided in a size that exposes two or more nozzle plates 12.

[0071] Since the fixing plate 60 made of such a metal is fixed to the lower wall 45, the heat of the heater 70 fixed to the retainer 40 can be transferred to the "first flow path" in the head chip 10 via the lower wall 45, the fixing plate 60, and the plastic substrate 17. Moreover, in the present embodiment, since there is a partition wall 48 between the head chips 10 adjacent in the +Y direction as described above, even for the head chip 10 disposed separately from the heater 70, the heat of the heater 70 can be transferred to the "first flow path" in the head chip 10 via the partition wall 48, the fixing plate 60, and the plastic substrate 17. Therefore, the plurality of head chips 10 can be effectively heated by the heater 70 via the fixing plate 60. In addition, by fixing the fixing plate 60 to the partition wall 48, the heat of the heater 70 can be transferred to the central portion side in the plane including the ±X direction and the ±Y direction of the retainer 40 via the lower wall 45, the fixing plate 60, and the partition wall 48, and the entire retainer 40 can be heated by the heater 70 in a manner that reduces bias, and it is possible to suppress a deviation from occurring in the heating temperature of the ink in the plurality of second flow paths 50.

[0072] In such a retainer 40, second flow paths 50 are provided that communicate with the inlet 32 and the inlet liquid chamber 31, which are the "first flow paths" provided in the housing 13 of the head chip 10, respectively. In the present embodiment, since four head chips 10 each having two independent "first flow paths" are fixed in the retainer 40, a total of eight second flow paths 50 are provided in the retainer 40. The second flow paths 50 are provided such that one end opens to the +Z direction surface of the retainer 40 (opens to the bottom surface of the recess 47 in the present embodiment) and the other end opens to the -Z direction surface of the retainer 40. One end of the second flow path 50 that opens to the bottom surface of the recess 47 is connected to the inlet 32, which is a part of the "first flow path" provided in the housing 13 of the head chip 10.

[0073] Here, each second flow path 50 of the present embodiment includes a first portion 51, a second portion 52, and a third portion 53. The first portion 51 is provided so as to penetrate the first member 41 in the Z direction. The -Z direction end portion of the first portion 51 is provided within a protruding portion 41a that protrudes further in the -Z direction than the upper wall 44 of the retainer 40. That is, the -Z direction end portion of the second flow path 50 is provided so as to protrude in the -Z direction compared to the upper wall 44. In the present embodiment, the portion of the first portion 51 provided within the protruding portion 41a that protrudes in the -Z direction compared to the upper wall 44 is referred to as the connecting portion 51a. Further, in the present embodiment, the protruding portion 41a is provided so as to be integrally continuous with the first member 41. Of course, it may be configured such that the protruding portion 41a is fixed to the first member 41 in a separate manner from the first member 41.

[0074] The second portion 52 is provided along a plane including a direction intersecting the +Z direction (including the ±X directions and the ±Y directions orthogonal to the +Z direction in the present embodiment) between the first member 41 and the second member 42. That is, in the present embodiment, this second portion 52 is referred to as an "intersecting portion" extending in a direction intersecting the +Z direction, which is the "first direction". The second portion 52 is guided and arranged along a plane including the ±X directions and the ±Y directions such that one end communicates with the +Z direction end portion of the first portion 51 and the other end communicates with the -Z direction end portion of the third portion 53. Further, the second portion 52 of the present embodiment is formed by providing a recess in the +Z direction surface of the first member 41 and covering the opening of the recess with the second member 42. Of course, the second portion 52 may also be formed by providing a recess in the -Z direction surface of the second member 42 and covering the opening of the recess of the second member 42 with the first member 41. Further, it may also be formed by providing recesses in both the first member 41 and the second member 42 and joining the openings of the two recesses together. Further, although in the present embodiment, the second portion 52, which is the "intersecting portion", is provided between the first member 41 and the second member 42, it is not particularly limited thereto, and it may be configured such that the "intersecting portion" is provided between the second member 42 and the third member 43.

[0075] The third portion 53 is provided so as to straddle the +Z direction and penetrate the second member 42 and the third member 43. The third portion 53 is provided such that the -Z direction end portion communicates with the end portion of the second portion 52. Further, the +Z direction end portion of the third portion 53 is provided such that it opens to the bottom surface of the recess 47, which is the +Z direction surface of the retainer 40. In the present embodiment, this third portion 53 becomes a "connecting portion" that communicates with the "first flow path", which is the introduction port 32, provided in the housing 13 of the head chip 10.

[0076] That is, the first part 51 and the third part 53 of the second flow path 50 constituting the present embodiment extend along the +Z direction as the "first direction", and the second part 52 constituting the second flow path 50 extends in a plane including a direction intersecting the +Z direction (including the ±X direction and the ±Y direction orthogonal to the +Z direction in the present embodiment). In this way, by providing the second part 52 as the "crossing part" on the second flow path 50, the second flow path 50 can be guided in a direction intersecting the +Z direction, and the interference between the plurality of second flow paths 50 in the holder 40 can be suppressed. Moreover, the interference of the second flow path 50 with other openings or other components can be suppressed. Furthermore, the enlargement of the holder 40 can be suppressed by suppressing the interference of the second flow path 50.

[0077] In the holder 40 provided with a plurality (eight in the present embodiment) of such second flow paths 50, a heater 70 for heating the ink flowing in the plurality of second flow paths 50 is provided. Here, although the heater 70 is not particularly limited, in the present embodiment, it is constituted by a flexible thin film heater. As Figure 8 shown, the heater 70 constituted by the thin film heater has a heat generating portion 71 and a thin film member 72 covering the heat generating portion 71. Specifically, the thin film member 72 has a base film serving as a base material and a protective film serving as an insulator, and the thin film heater is constituted by laminating the base film, the heat generating portion 71, and the protective film in this order. The heat generating portion 71 of the heater 70 is, for example, a heat generating resistor such as stainless steel, copper, tungsten, nickel alloy, or aluminum foil. In the present embodiment, it is set that, as the heat generating resistor of the heat generating portion 71, stainless steel with high ink resistance is used. As the base film and the protective film, preferably, a film having insulating properties can be used. For example, polyimide, polyethylene terephthalate, polyethylene naphthalate, or the like can be adopted. In addition, instead of the protective film of the thin film member 72, a film-shaped solder resist having insulating properties can be used. Furthermore, as Figure 8 shown, since the heat generating portion 71 is not provided at the end of the heater 70 as the thin film heater, only the thin film member 72 exists.

[0078] In addition, providing the heater 70 in the holder 40 means that the heater 70 is in direct contact with the holder 40. For example, although other components formed of a material having high thermal conductivity can be provided between the holder 40 and the heater 70, the heating efficiency of the heater 70 will be reduced, and the holder 40 provided with the heater 70 will be enlarged, resulting in the enlargement of the recording head 1. Therefore, preferably, the holder 40 and the heater 70 are in direct contact.

[0079] The heater 70 of the present embodiment is arranged so as to surround a plurality of second flow paths 50 when viewed from above in the +Z direction, and to overlap at least a part of the second flow paths 50 when viewed in the in-plane direction including the directions orthogonal to the +Z direction, that is, the ±X directions and the ±Y directions. That is to say, as long as the heater 70 is arranged at a position where at least a part of the heater 70 overlaps at least one of the first part 51, the second part 52, and the third part 53 constituting the second flow path 50 when viewed in the in-plane direction including the ±X directions and the ±Y directions. In this way, by arranging the heater 70 so as to surround the plurality of second flow paths 50, even for the second flow paths 50 arranged separately from the outer peripheral wall 46 of the holder 40, the heater 70 can effectively heat them. That is, the second flow paths 50 on the central side in the ±Y direction among the plurality of second flow paths 50 are separated from the heaters 70 provided on the outer peripheral walls 46 on both sides in the ±Y direction of the holder 40. However, by arranging the heater 70 so as to surround the plurality of second flow paths 50, that is, by providing the heaters 70 on the outer peripheral walls 46 on both sides in the ±X direction of the holder 40, the second flow paths 50 arranged separately from the outer peripheral walls 46 on both sides in the ±Y direction can be heated by the heaters 70 provided on the outer peripheral walls 46 on both sides in the ±X direction. In addition, the heater 70 can suppress heat dissipation from the holder 40 by being arranged so as to surround the plurality of second flow paths 50.

[0080] In addition, preferably, when the heater 70 is viewed in the in-plane direction including the directions orthogonal to the +Z direction, that is, the ±X directions and the ±Y directions, the heater 70 is arranged so as to overlap across the second part 52 as the "crossing part" and the third part 53 as the "connecting part". That is to say, as long as the heater 70 is arranged so as to overlap across at least a part of the second part 52 on the side connected to the third part 53 and at least a part of the third part 53 on the side connected to the second part 52.

[0081] Although the length of the flow path of the second flow path 50 is increased by providing the second part 52, the heater 70 can effectively heat the ink passing through the second part 52 by heating the second part 52 where the flow path length is increased. In addition, since the heater 70 extends across the second part 52 and the third part 53 and extends in the +Z direction, the length of the heater 70 for heating the ink in the +Z direction can be increased, and the ink can be effectively heated.

[0082] That is to say, preferably, when the heater 70 is viewed in the direction orthogonal to the +Z direction, the heater 70 is arranged at a position overlapping the second part 52, and more preferably, it is arranged so that the length overlapping the second flow path 50 in the +Z direction is as long as possible.

[0083] The heater 70 of the present embodiment is arranged such that its position in the +Z direction relative to the holder 40 overlaps the first part 51, the second part 52, and the third part 53 of the second flow path 50 of the holder 40. That is, the heater of the present embodiment is arranged to completely overlap the second part 52 when viewed in the in-plane direction including the ±X directions and the ±Y directions, and to overlap a part of the first part 51 and the third part 53 on the side communicating with the second part 52. Thus, the heater 70 can heat the ink flowing in the first part 51 in addition to the second part 52 and the third part 53, and therefore, can effectively heat the ink flowing in the second flow path 50.

[0084] In addition, the heater 70 formed of a thin film heater is wound so as to cover the outer peripheral wall 46 of the holder 40 when viewed from above in the +Z direction, and is fixed to the outer peripheral wall 46. That is, the heater 70 includes a first part 73 extending in the +Y direction, which is the "third direction" in which the head chips 10 are arranged, and a second part 74 extending in a direction intersecting the +Z direction and the +Y direction (in the present embodiment, the +X direction orthogonal to the +Z direction and the +Y direction). The first part 73 is provided on the outer peripheral walls 46 on both sides in the ±X direction of the outer peripheral wall 46. In addition, the second part 74 is provided on the outer peripheral walls 46 on both sides in the ±Y direction of the outer peripheral wall 46. In this way, by simply winding the flexible long heater 70 around the outer peripheral wall 46 of the holder 40, the heater 70 can be easily mounted on the holder 40. In addition, by winding the heater 70 around the entire circumference of the outer peripheral wall 46 of the holder 40, heat dissipation of the holder 40 can be suppressed, and the holder 40 can be effectively heated by the heater 70.

[0085] In addition, the method of fixing the heater 70 to the outer peripheral wall 46 is not particularly limited. The flexible long heater 70 can be simply wound around the outer peripheral wall 46. In addition, the ends of the heater 70 can be bonded to each other in a state where the heater 70 is wound around the outer peripheral wall 46. In addition, the heater 70 can be bonded to the outer peripheral wall 46 with an adhesive, or a part of the heater 70 can be fused to the outer peripheral wall 46. Moreover, the heater 70 can be fixed to the outer peripheral wall 46 with screws or bolts.

[0086] Here, as Figure 8As shown, both end portions of the heater 70 wound around the outer peripheral wall 46 of the holder 40 are arranged with a gap therebetween so as not to overlap each other. That is, one end portion 72a and the other end portion 72b of the thin film member 72 of the heater 70 are arranged with a gap therebetween so as not to overlap each other. In this way, by arranging both end portions of the heater 70 with a gap therebetween on the outer peripheral wall 46 of the holder 40 so as not to overlap each other, an increase in thickness due to the overlap of the two end portions of the heater 70 can be suppressed, and the enlargement of the holder 40 around which the heater 70 is wound can be suppressed. That is to say, the fact that the heater 70 is wound so as to cover the outer peripheral wall 46 of the holder 40 in a plan view observed in the +Z direction is not limited to the case where the heater 70 is continuously provided across the entire circumference of the outer peripheral wall 46 in a plan view observed in the +Z direction, and also includes the case where the heater 70 is wound so as to expose a part of the outer peripheral wall 46 of the holder 40. For example, the fact that the heater 70 is wound so as to cover the outer peripheral wall 46 of the holder 40 means that the heater 70 only needs to cover 75% or more of the entire circumference of the outer peripheral wall 46. In addition, the fact that the heater 70 surrounds a plurality of second flow channels 50 means that, in a plan view observed in the +Z direction, it surrounds in three or more of the four directions of the +X direction, -X direction, +Y direction, and -Y direction that surround the plurality of second flow channels 50.

[0087] In addition, as Figure 9 shown, it may also be set that, among both end portions of the heater 70 wound around the outer peripheral wall 46 of the holder 40, one end portion 71a and the other end portion 71b of the heat generating portion 71 overlap each other. Thus, in a plan view observed in the +Z direction, the heat generating portion 71 can cover the outer peripheral wall 46 of the holder 40 across the entire circumference, and the holder 40 can be effectively heated.

[0088] Moreover, as Figure 10 shown, it may also be arranged that, among both end portions of the heater 70 wound around the outer peripheral wall 46 of the holder 40, one end portion 71a and the other end portion 71b of the heat generating portion 71 do not overlap each other, while one end portion 72a and the other end portion 72b of the thin film member 72 overlap each other. Thus, in a plan view observed in the +Z direction, the area where the heat generating portion 71 covers the outer peripheral wall 46 of the holder 40 can be increased, the heating efficiency of the holder 40 can be improved, and the enlargement of the outer periphery of the holder 40 around which the heater 70 is wound can be suppressed.

[0089] In this way, by providing the heater 70 on the holder 40 provided with the second flow path 50, the ink passing through the second flow path 50 can be heated by the heater 70. In particular, in the present embodiment, the heater 70 surrounds the plurality of second flow paths 50, and when viewed in the in-plane direction including the ±X directions and the ±Y directions, the heater 70 is arranged so as to overlap at least a part of the second flow path 50, so that the ink passing through the plurality of second flow paths 50 can be effectively heated by the heater 70.

[0090] In addition, in the holder 40, a first wiring insertion hole 49 is provided for leading out the wiring board 23 of the head chip 10 fixed to the +Z direction side to the -Z direction side of the holder 40. The first wiring insertion hole 49 is independently provided for each wiring board 23. That is, the first wiring insertion hole 49 is provided in such a manner that one end opens at the bottom surface of the recess 47 and the other end opens at the surface of the holder 40 in the +Z direction. Therefore, a total of four first wiring insertion holes 49 are provided in the holder 40.

[0091] The holder 40 around which the heater 70 is wound on the outer peripheral wall 46 is covered with the holder cover 80.

[0092] The holder cover 80 has a concave-shaped storage portion 81 that opens to the surface on the +Z direction side, and the holder 40 around which the heater 70 is wound is stored in this storage portion. The opening of the surface on the +Z direction side of the storage portion 81 is set to be slightly larger than the outer shape of the holder 40 around which the heater 70 is wound and smaller than the convex portion 43a of the third member 43 of the holder 40. Therefore, when the -Z direction side of the holder 40 is stored in the storage portion 81 of the holder cover 80, the surface on the +Z direction side where the storage portion 81 of the holder cover 80 opens and the surface on the -Z direction side of the convex portion 43a of the holder 40 are fixed to each other in a state of being in contact with each other. The fixing method of the holder cover 80 and the holder 40 is not particularly limited, and it can be either by adhesion with an adhesive, or alternatively, by fixing with screws or bolts, etc. In addition, although not particularly illustrated, in the holder cover 80, an opening for leading out the wiring connected to the heater 70 to the outside is provided. This opening can be provided in such a manner that it opens to the surface on the -Z direction side of the holder cover 80, or can be provided in such a manner that it opens to the side surface intersecting the +Z direction. Of course, the wiring of the heater 70 can also be led out to the outside from the opening on the +Z direction side of the storage portion 81.

[0093] In addition, in the retainer cover 80, a first through-hole 82 into which the protrusion 41a of the retainer 40 is inserted is provided so as to penetrate in the +Z direction. That is, the first through-hole 82 is provided so as to penetrate the bottom surface of the storage portion 81 and the surface on the +Z direction side of the retainer cover 80. In a state where the retainer 40 is stored in the storage portion 81 of the retainer cover 80, the protrusion 41a of the retainer 40 penetrates through the first through-hole 82 and protrudes toward the -Z direction side.

[0094] In addition, in the retainer cover 80, a second wiring insertion hole 83 communicating with the first wiring insertion hole 49 of the retainer 40 is provided so as to penetrate in the +Z direction. Therefore, the wiring substrate 23 of the head chip 10 fixed to the surface on the +Z direction of the retainer 40 is led out to the -Z direction side of the retainer cover 80 through the first wiring insertion hole 49 of the retainer 40 and the second wiring insertion hole 83 of the retainer cover 80.

[0095] In addition, on the surface on the -Z direction of the retainer cover 80, a relay substrate 90 shared by a plurality of wiring substrates 23 is held. In the relay substrate 90, a third wiring insertion hole 91 communicating with the second wiring insertion hole 83 of the retainer cover 80 is provided. Therefore, the wiring substrate 23 of the head chip 10 is led out to the -Z direction side of the relay substrate 90 through the first wiring insertion hole 49 of the retainer 40, the second wiring insertion hole 83 of the retainer cover 80, and the third wiring insertion hole 91 of the relay substrate 90, and is connected to the relay substrate 90 on the surface on the -Z direction side of the relay substrate 90.

[0096] In addition, in the relay substrate 90, a second through-hole 92 communicating with the first through-hole 82 of the retainer cover 80 is provided so as to penetrate in the +Z direction. Therefore, the protrusion 41a of the retainer 40 is provided so as to protrude toward the -Z direction compared to the relay substrate 90 through the first through-hole 82 of the retainer cover 80 and the second through-hole 92 of the relay substrate 90. Ink from the outside is supplied to the opening of the second flow path 50 of the protrusion 41a that protrudes toward the -Z direction compared to the relay substrate 90, that is, the opening of the connection portion 51a. Although the protrusion 41a in the present embodiment is a flow path tube in which a part (connection portion 51a) of the second flow path 50 is formed inside, it may also be a flow path needle with a tapered tip on the -Z direction side.

[0097] In such a retainer cover 80, a head outer wall 84 is provided which is arranged with a heater 70 interposed therebetween and the retainer 40. That is, the head outer wall 84 is a portion that is located outside compared to the storage portion 81 which divides the inner side surface of the storage portion 81 in a direction orthogonal to the +Z direction. The head outer wall 84 is made of a material having a lower thermal conductivity than the retainer 40. For example, it is made of resin. In the present embodiment, it is assumed that the entire retainer cover 80 is made of a material having a lower thermal conductivity than the retainer 40. For example, it is made of resin. Of course, it is not limited thereto, and at least the head outer wall 84 of the retainer cover 80 may be formed of a material having a lower thermal conductivity than the retainer 40, and other portions may be formed of different materials. In addition, as the resin used in the head outer wall 84 of the retainer cover 80, for example, the same resin as the housing 13 can be used. In this way, by forming the head outer wall 84 of a material having a lower thermal conductivity than the retainer 40, it is possible to suppress the heat of the heater 70 and the heat of the retainer 40 heated by the heater 70 from being dissipated through the head outer wall 84. In addition, in the present embodiment, by forming the entire retainer cover 80 of a material having a lower thermal conductivity than the retainer 40, it is possible to further suppress the heat of the heater 70 and the retainer 40 from being dissipated. Therefore, it is not necessary to overheat the heater 70, and it is possible to easily perform temperature management of the ink flowing in the second flow path 50 by controlling the temperature of the heater 70.

[0098] In contrast, when the thermal conductivity of the head outer wall 84 is the same as or higher than that of the retainer 40, the heat of the heater 70 and the heat of the retainer 40 heated by the heater 70 are dissipated from the head outer wall 84. That is, the temperature on the outer side of the head outer wall 84, which is opposite to the storage portion 81, such as the temperature of a holding member such as a carriage that holds the retainer cover 80 or the outside air temperature, easily affects the heater 70 and the retainer 40, and thus adverse phenomena such as overheating of the heater 70 or frequent temperature control of the heater 70 are likely to occur.

[0099] As described above, in the recording head 1 which is the liquid ejection head of the present embodiment, there are provided: a plurality of head chips 10 which have a nozzle plate 12 and a housing 13, the nozzle plate 12 has a plurality of nozzles 11 for ejecting ink as a liquid in the +Z direction which is the "first direction", and the housing 13 is formed with one or more "first flow paths" that communicate with at least a part of the plurality of nozzles 11, namely an introduction port 32 and an introduction liquid chamber 31; a holder 40 which fixes the plurality of head chips 10, and is configured to include metal or ceramic, and has a plurality of second flow paths 50 that communicate with at least one of the plurality of introduction ports 32 and the introduction liquid chamber 31; and a heater 70 which heats the holder 40. In the present embodiment, in the housing 13, there are formed two introduction ports 32 and an introduction liquid chamber 31 which are the "first flow paths" that communicate with the plurality of nozzles 11. In addition, in the holder 40, there are provided second flow paths 50 that communicate with the plurality of introduction ports 32 and the introduction liquid chamber 31 respectively.

[0100] In this way, since the second flow path 50 disposed near the head chip 10 can be heated by the heater 70, ink that is sufficiently heated can be supplied to the head chip 10. In addition, since the holder 40 heated by the heater 70 is made of metal or ceramic with a relatively high thermal conductivity, the ink flowing in the plurality of second flow paths 50 can be sufficiently heated by the heater 70, and ink that is sufficiently heated can also be supplied to the head chip 10 disposed at a position separated from the heater 70. Therefore, it is possible to suppress a decrease in the ejection characteristics of the ink by reducing the viscosity of the ink ejected from the head chip 10. Moreover, since the heater 70 is not structured to heat the head chip 10 itself, the layout of the wiring connected to the heater 70 and the structure of the recording head 1 can be simplified.

[0101] In addition, in the recording head 1 of the present embodiment, preferably, the housing 13 is made of resin. In this way, by forming the housing 13 of resin with a relatively low thermal conductivity, a decrease in the temperature of the ink in the "first flow paths" of the housing 13, namely the introduction port 32 and the introduction liquid chamber 31, disposed near the nozzles 11 can be suppressed. Therefore, the ink whose temperature decrease has been suppressed by the introduction port 32 and the introduction liquid chamber 31 can be guided to the nozzles 11, and the ink with reduced viscosity can be ejected from the nozzles 11.

[0102] In addition, in the recording head 1 of the present embodiment, preferably, when viewed from above in the +Z direction as the "first direction", the heater 70 surrounds the plurality of second flow paths 50, and when viewed in the in-plane direction including the ±X directions and the ±Y directions which are orthogonal to the +Z direction, the heater 70 overlaps at least a part of the second flow paths 50. Thus, since the heater 70 is arranged so as to surround the plurality of second flow paths 50, the second flow paths 50 which are separately arranged from the outer peripheral wall 46 of the holder 40 can also be effectively heated by the heater 70. In addition, heat dissipation from the holder 40 can be suppressed by arranging the heater 70 so as to surround the plurality of second flow paths 50.

[0103] In addition, in the recording head 1 of the present embodiment, preferably, the second flow path 50 has a "crossing portion", that is, a second portion 52 extending in a direction crossing the +Z direction as the "first direction", and a "communicating portion", that is, a third portion 53 extending in the +Z direction and communicating the second portion 52 with the inlet 32 of the "first flow path" and the introduction liquid chamber 31 of the housing 13. The heater 70 is arranged so as to overlap across the second portion 52 and the third portion 53 when viewed in a direction orthogonal to the +Z direction. In this way, by providing the second portion 52 as the crossing portion on the second flow path 50, the flow path length of the second flow path 50 can be increased, and the ink flowing in the second flow path 50 can be effectively heated by the heater 70. In addition, since the heater 70 extends in the +Z direction across the second flow path 50 as the "crossing portion" and the third portion 53 as the "communicating portion", the ink flowing in the second flow path 50 can be effectively heated by the heater 70.

[0104] In addition, although in the present embodiment, one second portion 52 as the "crossing portion" and one third portion 53 as the "communicating portion" are respectively provided on each of the plurality of second flow paths 50, it is not particularly limited thereto. It may also be arranged such that the second flow path 50 communicates with two or more "first flow paths" by providing a plurality of second portions 52 as the "crossing portion" on the second flow path 50. That is, the second flow path 50 may also be a branch flow path for distributing liquid to two or more "first flow paths". In other words, it is not necessary to make the number of second flow paths 50 correspond one-to-one to the number of "first flow paths" as in the present embodiment, and the holder 40 may also have a structure in which the second flow paths 50 communicate with at least one of the plurality of "first flow paths" of the plurality of head chips 10 fixed to the holder 40.

[0105] In addition, in the recording head 1 of the present embodiment, preferably, the holder 40 has an outer peripheral wall 46 that surrounds the plurality of second flow paths 50 in a plan view observed in the +Z direction as the "first direction". The heater 70 is a flexible thin film heater, and is wound so as to cover the entire circumference of the outer peripheral wall 46 in a plan view observed in the +Z direction, and is fixed to the outer peripheral wall 46. In this way, by simply winding the flexible long heater 70 around the outer peripheral wall 46 of the holder 40, the heater 70 can be easily mounted on the holder 40. In addition, since the heater 70 is wound across the entire circumference of the outer peripheral wall 46, heat dissipation of the holder 40 can be suppressed, and the holder 40 can be effectively heated by the heater 70. In addition, the heater 70 may be provided so as to cover the outer peripheral wall 46 in the +Z direction, or may be provided so as to cover only a part of the outer peripheral wall 46 in the +Z direction.

[0106] In addition, in the recording head 1 of the present embodiment, preferably, a fixing plate 60 is provided. The fixing portion 60 has a plurality of exposed openings 61 for exposing the plurality of nozzles 11 of the head chip 10, and is made of metal. The holder 40 has a lower wall 45 for fixing the plurality of head chips 10 and the fixing plate 60. The lower wall 45 has a plurality of recesses 47 for accommodating the respective head chips 10. That is, in the holder 40, by providing the recesses 47 corresponding to the plurality of head chips 10 respectively, a partition wall 48 of the holder 40 is provided between the adjacent head chips 10. Therefore, the rigidity of the holder 40 can be improved, and deformation of the fixing plate 60 can be suppressed. In addition, by forming the fixing plate 60 of metal, heat of the heater 70 can be transferred through the lower wall 45 including the partition wall 48 to which the fixing plate 60 is fixed, and the holder 40 can be effectively heated, thereby effectively heating the plurality of head chips 10.

[0107] Thus, in the present embodiment, since the ink supplied to the head chip 10 is heated by the heater 70 in the second flow path 50, ultraviolet curable ink or solvent-based ink can be used as the ink used in the recording head 1. That is, although ultraviolet curable ink or solvent-based ink has a high viscosity at room temperature, since the viscosity of the high-viscosity ink is reduced by heating with the heater 70, a decrease in the ejection characteristics of ink droplets can be suppressed.

[0108] In addition, solvent-based inks refer to inks in which the main component of the solvent is an organic solvent, and are also called solvent inks or non-aqueous inks. Solvent-based inks are inks containing any one or more of ethylene glycol ethers, ethylene glycol ether esters, dibasic acid esters, ester solvents, hydrocarbon solvents, and ethanol-based solvents. In addition, ultraviolet curable inks refer to, for example, UV inks including monomers or oligomers that are cured by generating a polymerization reaction through ultraviolet irradiation. Examples of the composition of the ultraviolet curable ink include inks containing any one of (meth)acrylates, (meth)acrylamides, and N-vinyl compounds as the polymerizable compound.

[0109] In addition, in the recording head 1 of the present embodiment, preferably, a head outer wall 84 is provided. The head outer wall 84 is arranged so as to have a heater 70 interposed therebetween with respect to the holder 40, and the heat conductivity of the head outer wall 84 is lower than that of the holder 40. Thus, by forming the head outer wall 84 with a material having a heat conductivity lower than that of the holder 40, it is possible to suppress the heat of the heater 70 and the heat of the holder 40 heated by the heater 70 from being dissipated through the head outer wall 84. Therefore, it is not necessary to excessively heat the heater 70, and it is possible to suppress a decrease in the life of the components constituting the recording head 1, and it is possible to easily perform temperature management of the ink flowing in the second flow path 50 by temperature control of the heater 70.

[0110] In addition, although in the above-described Embodiment 1, the calorific value of the heater 70 is the same in the circumferential direction across the outer peripheral wall 46, it is not particularly limited thereto. For example, the calorific value per unit area of the first portion 73 of the heater 70 may be made larger than the calorific value per unit area of the second portion 74. In addition, the calorific value per unit area in the first portion 73 and the second portion 74 of the heater 70 can be adjusted, for example, by changing the width of the heater pattern (wiring) of the heating resistor of the heating portion 71 and the density per unit area where the heating resistor is provided. Specifically, the narrower the width of the heater pattern of the heating resistor of the heating portion 71, the larger the calorific value per unit area, and in addition, the higher the density of the heating resistor, the larger the calorific value per unit area.

[0111] That is, a plurality of head chips 10 are arranged and configured in the "+Y direction", which is the "third direction" orthogonal to the "+Z direction" as the "first direction". The heater 70 has a first portion 73 extending in the +Y direction and a second portion 74 extending in a direction orthogonal to the +Z direction and intersecting the +Y direction. The calorific value per unit area of the first portion 73 is greater than the calorific value per unit area of the second portion 74. Here, it is preferable that the arrangement direction of the plurality of second flow channels 50 is the same as the arrangement direction of the plurality of head chips 10. Thus, the arrangement of the second flow channels 50 can be easily implemented, thereby simplifying the structure. Moreover, the deviation in the flow channel length of the plurality of second flow channels 50 can be suppressed, and the deviation in the ink droplet ejection characteristics among the plurality of head chips 10 can be suppressed. In this way, when the plurality of second flow channels 50 are arranged in the +Y direction, a deviation occurs in the distance between the outer peripheral walls 46 on both sides in the ±Y direction of the holder 40. In contrast, when the plurality of second flow channels 50 are arranged in the +Y direction, the deviation in the distance between the outer peripheral walls 46 on both sides in the ±X direction of the holder 40 becomes smaller. That is, the deviation in the distance in the +Y direction between the plurality of second flow channels 50 and the second portion 74 of the heater 70 is large, and the deviation in the distance in the +X direction from the first portion 73 is small. Therefore, by making the calorific value of the first portion 73 greater than that of the second portion 74, the deviation in the temperature for heating the plurality of second flow channels 50 in the holder 40 can be reduced, and the temperature deviation of the ink flowing in the plurality of second flow channels 50 can be reduced. That is, although it is difficult to heat the ink in the second flow channel 50 that supplies ink to the head chip 10 disposed on the central side in the ±Y direction, which is the arrangement direction of the head chips 10, by increasing the calorific value of the first portion 73 extending in the +Y direction, the ink in the second flow channel 50 that supplies ink to the head chip 10 disposed on the central side can be easily heated. Therefore, the deviation in the temperature for heating the plurality of second flow channels 50 in the holder 40 can be reduced.

[0112] That is to say, in other words, a plurality of second flow channels 50 are arranged and disposed in the "+Y direction", which is the "third direction" orthogonal to the "+Z direction" that is the "first direction". The heater 70 has a first portion 73 extending in the +Y direction and a second portion 74 extending in a direction orthogonal to the +Z direction and intersecting the +Y direction. The heat generation per unit area of the first portion 73 is greater than the heat generation per unit area of the second portion 74. Thereby, the situation where a deviation occurs in the temperature for heating the plurality of second flow channels 50 in the holder 40 can be reduced. In addition, although in the present embodiment, four second flow channels 50 are arranged in the +Y direction and two are arranged in the +Y direction, for a total of eight, the direction in which the second flow channels 50 are arranged and disposed means the arrangement direction in which the number of second flow channels 50 is larger, that is, in the present embodiment, it means the +Y direction. Thereby, the heat generation amount of the first portion 73 extending in the direction in which the number of arrangements of the second flow channels 50 is larger can be made higher than the heat generation amount of the second portion 74 extending in the direction in which the number of arrangements of the second flow channels 50 is smaller, thereby reducing the temperature deviation of the ink flowing in the plurality of second flow channels 50.

[0113] In addition, although in the present embodiment, the holder 40 has a rectangular shape when viewed from above in the +Z direction, it is not limited thereto. The holder 40 may also be a shape having a rectangular shape as a basic shape and having rounded corners when viewed from above in the +Z direction. Here, Figure 11 shows a modified example of the holder 40. In addition, Figure 11 is a top view showing modified examples of the holder 40 and the heater 70.

[0114] As Figure 11 shown, in the holder 40, when viewed from above in the +Z direction, three of the four corner portions 40a to 40d, namely, the corner portions 40a to 40c, are chamfered into arc surfaces with curvature, that is, so-called R surfaces, and one corner portion 40d is a non-chamfered right angle.

[0115] In order to wind the heater 70 around the outer peripheral wall 46 of such a retainer 40, it is only necessary to join the both end portions of the heater 70 at the non-chamfered corner portion 40d. Thus, in the corner portions 40a to 40c, since the heater 70 is bent along the curved surface, the case of being bent can be suppressed, and thus, disconnection of the heating portion 71 or peeling from the outer peripheral wall 46 of the retainer 40 can be suppressed. Further, by joining the both end portions of the heater 70 at the corner portion 40d, the heater 70 can be arranged over the entire circumference of the outer peripheral wall 46, and the stress applied to the both end portions of the heater 70 in the direction of peeling from the retainer 40 can be reduced, and thus, peeling from the retainer 40 of the heater 70 can be suppressed. Incidentally, when the both end portions of the heater 70 are joined at the sides along the ±X direction or the ±Y direction of the outer peripheral wall 46, the distance from the portion bent through the corner portions 40a to 40d of the heater 70 to the both end portions of the heater 70 becomes short. Therefore, the force resisting the bending of the heater 70 is applied to the both end portions of the heater 70 as a reaction force to peeling from the retainer 40, and thus, the both end portions of the heater 70 are likely to peel from the retainer 40. Further, by arranging the both end portions of the heater 70 at the corner portion 40d, compared with the case of joining at the sides along the ±X direction or the ±Y direction of the outer peripheral wall 46, since the both end portions of the heater 70 can be separated from the plurality of second flow paths 50, the plurality of second flow paths 50 can be effectively heated by the heater 70.

[0116] Further, by forming the corner portions 40a to 40c of the retainer 40 into R surfaces, the entire length of the heater 70 wound around the outer peripheral wall 46 can be shortened, and thus, the cost can be reduced.

[0117] Here, the above-described recording head 1 of the present embodiment is mounted on an inkjet recording apparatus I. Referring to Figure 12 and Figure 13 , an inkjet recording apparatus I as an example of the liquid ejecting apparatus of the present embodiment will be described. Further, Figure 12 FIG. is a diagram showing a schematic configuration of the inkjet recording apparatus I, Figure 13 and FIG. is a main part cross-sectional view of the recording head 1 and the holding member 7.

[0118] As Figure 12 shown, the inkjet recording apparatus I includes a recording head 1, a liquid container 3, a conveying mechanism 4 for conveying a medium S, a control unit 5 as a control device, and a moving mechanism 6.

[0119] The liquid container 3 stores the ink ejected from the recording head 1. As the liquid container 3, for example, a cartridge that can be detached from and attached to the inkjet recording apparatus I, an ink bag formed of a flexible film, an ink tank for replenishing ink, etc. can be cited. In the present embodiment, as the liquid container 3, a cartridge detachably provided on the recording head 1 is used. Further, in the liquid container 3, a plurality of types of inks different in color or type are independently stored. In the present embodiment, in the liquid container 3, inks of four colors, cyan (C), fluorescent yellow (FY), fluorescent pink (FP), and black (K), are independently stored.

[0120] Although not particularly illustrated, the control unit 5 is configured to include, for example, a control device such as a CPU (Central Processing Unit) or an FPGA (Field Programmable Gate Array), and a storage device such as a semiconductor memory. The control unit 5 controls each element of the inkjet recording apparatus I, that is, the conveyance mechanism 4, the moving mechanism 6, the recording head 1, etc., by executing the program stored in the storage device by the control device.

[0121] Further, the control unit 5 controls the heater 70 to control the temperature of the ink flowing in the second flow path 50. Further, the control unit 5 of the present embodiment controls the heater 70 based on the temperature measured by an unillustrated temperature sensor provided in the recording head 1. Although not particularly illustrated, it is preferable that the temperature sensor is provided on the holder 40 so as to detect the temperature of the holder 40 provided with the second flow path 50. For example, it is sufficient to provide a recess in the central portion of the upper wall 44 of the holder 40 in the in-plane direction including the ±X direction and the ±Y direction and dispose the temperature sensor in the recess. Thereby, the temperature of the ink flowing in the second flow path 50 can be easily obtained by the temperature sensor, and the temperature of the ink flowing in the second flow path 50 can be controlled with high accuracy by the heater 70. Of course, although it may be configured such that the temperature sensor is provided on the lower wall 45 side of the holder 40, since the head chip 10 is fixed on the lower wall 45 side, the structure may be complicated or the wiring of the temperature sensor may be difficult to arrange. Therefore, it is preferable that the temperature sensor is provided on the upper wall 44 side. Further, the temperature sensor may be provided on the relay substrate 90, may be provided on the holder cover 80, or may be provided on the fixing plate 60. Further, the temperature sensor is not limited to a contact type, and may be a non-contact type sensor.

[0122] In addition, although in this embodiment, the control unit 5 that controls printing also controls the heater 70, it is not particularly limited thereto. For example, it may be configured such that the control device that controls the heater 70 and the control unit 5 that controls printing are provided separately. Further, for example, it may be configured such that a temperature detection device such as a thermistor is provided on the recording head 1 to detect the temperature of an object, and the control unit 5 controls the heater 70 to make the object a fixed temperature.

[0123] The conveyance mechanism 4 is a mechanism that is controlled by the control unit 5 and conveys the medium S in the +X direction. For example, it includes conveyance rollers 4a. In addition, the conveyance mechanism 4 that conveys the medium S is not limited to the conveyance rollers 4a, and may also be a mechanism that conveys the medium S by a belt or a drum.

[0124] The moving mechanism 6 is controlled by the control unit 5 and reciprocates the recording head 1 in the ±Y direction. The ±Y direction in which the recording head 1 reciprocates by the moving mechanism 6 is a direction that intersects the +X direction in which the medium S is conveyed.

[0125] Specifically, the moving mechanism 6 of this embodiment includes a holding member 7 that holds the recording head 1, a conveyor belt 8, and a guide rail 9. The holding member 7 is a substantially box-shaped structure that houses the recording head 1, that is, a so-called carriage, and is fixed to the conveyor belt 8. The conveyor belt 8 is a seamless belt stretched along the ±Y direction. Under the control implemented by the control unit 5, the driving force of the drive motor 8a is transmitted to the conveyor belt 8, and the conveyor belt 8 rotates to make the recording head 1 and the holding member 7 reciprocate along the ±Y direction and along the guide rail 9. In addition, the liquid container 3 can be placed separately from the recording head 1 in the apparatus main body 2.

[0126] Here, as Figure 13 shown, the holding member 7 is arranged so as to be spaced from the heater 70 by the head outer wall 84. The holding member 7 may be a member made of a metal such as stainless steel or titanium, or may be a member made of resin. In addition, as the resin constituting the holding member 7, for example, the same material as the above-mentioned housing 13 can be used.

[0127] Here, the relationship between the second flow path 50, the head outer wall 84, and the temperature of the holding member 7 due to the difference in the material of the holding member 7 will be described.

[0128] While keeping the holding member 7 made of a metal material, since the heat conductivity is higher than that of a resin material, the temperature of the head outer wall 84 is more greatly affected by the outside air temperature and thus is likely to decrease. In contrast, while keeping the holding member 7 made of a resin material, since the heat conductivity is lower than that of a metal material, the temperature of the head outer wall 84 is not easily affected by the outside air temperature and is not easily decreased. However, in the present embodiment, even when the holding member 7 is made of an arbitrary material, since the plurality of second flow paths 50 are surrounded by the heater 70, the temperature of the ink flowing in the plurality of second flow paths 50 is substantially constant. However, since the metal material has higher rigidity than the resin material, forming the holding member 7 from the metal material suppresses deformation of the holding member 7, making it difficult to cause deviation in the ejection direction of the ink droplets due to deformation of the holding member 7 and the like. In contrast, since the resin material has lower heat conductivity than the metal material, forming the holding member 7 from the resin material suppresses heat dissipation of the heater 70 and the holder 40, and thus the holder 40 can be effectively heated by the heater 70. In addition, since the resin material has a lower cost than the metal material, forming the holding member 7 from the resin material can reduce costs.

[0129] In the present embodiment, a common heater 70 is provided for the plurality of second flow paths 50 provided in the holder 40. Since there is no need to provide a heater 70 for each second flow path 50, an increase in the number of components can be suppressed, thus reducing costs, and the structure or the layout of the wiring connected to the heater 70 can be simplified. In addition, the recording head 1 can be miniaturized.

[0130] As described above, in the inkjet recording apparatus I which is an example of the liquid ejection apparatus according to the present embodiment, a recording head 1 serving as the above-described "liquid ejection head" and a holding member 7 which holds the recording head 1 and is made of metal are provided. A part of the holding member 7 is arranged with a space from the heater 70 via the head outer wall 84.

[0131] In this way, compared with the case of being made of resin, by making the holding member 7 made of metal, the rigidity of the holding member 7 can be increased, thereby suppressing deformation of the holding member 7. Therefore, it is possible to suppress the occurrence of deviation in the ejection direction of the ink droplets due to deformation of the holding member 7 and the like. In addition, since even when the holding member 7 is made of a metal having a higher heat conductivity, the second flow path 50 of the holder 40 provided on the side opposite to the holding member 7 can be heated by the heater 70, it is possible to suppress the occurrence of insufficient heating of the ink flowing in the second flow path 50 and the like, and it is possible to suppress the occurrence of deviation in the temperature of the ink flowing in the plurality of second flow paths 50.

[0132] In addition, in an inkjet recording apparatus I which is an example of the liquid ejection apparatus of the present embodiment, it may be configured to include a recording head 1 as the above-described "liquid ejection head" and a holding member 7 that holds the recording head 1 and is made of resin. A part of the holding member 7 is arranged with a head outer wall 84 interposed therebetween from a heater 70.

[0133] In this way, since the heat conductivity of the holding member 7 can be reduced by forming the holding member 7 of resin as compared with the case of forming it of metal, heat dissipation of the heater 70 and the holder 40 can be suppressed, and thus the holder 40 can be effectively heated by the heater 70. In addition, the cost can be reduced by forming the holding member 7 of resin as compared with the case of forming it of metal.

[0134] In addition, the inkjet recording apparatus I of the present embodiment includes a recording head 1 as the above-described "liquid ejection head" and a control unit 5 as a control device that controls the heater 70. By controlling the heating temperature of the heater 70 by the control unit 5, the temperature of the ink in the second flow path 50 caused by the heater 70 can be controlled, and the ink at the most suitable temperature can be supplied to the head chip 10.

[0135] In addition, the inkjet recording apparatus I of the present embodiment includes a recording head 1 as the above-described "liquid ejection head" and a liquid container 3 that stores ink as a liquid ejected from the recording head 1. The ink as a liquid supplied from the liquid container 3 can be ejected from the recording head 1, and thus printing can be performed on the medium S.

[0136] In addition, although in the present embodiment, the holding member 7 is arranged with the head outer wall 84 interposed therebetween from the heater 70, it is not particularly limited thereto. Here, a modified example of the holding member 7 is shown in Figure 14 In addition, Figure 14 FIG. is a cross-sectional view showing main parts of the recording head 1 and the holding member 7A.

[0137] As Figure 14 shown, the holding member 7A is made of resin, and a part of the holding member 7A is arranged with the heater 70 interposed therebetween from the holder 40. In addition, as the resin constituting the holding member 7A, for example, the same material as the above-described housing 13 can be used.

[0138] In this manner, by forming the holding member 7A of resin and arranging a part of the holding member 7A with a heater 70 interposed therebetween from a retainer 40, the heater 70 can be covered with the holding member 7A having a lower thermal conductivity, and heat dissipation from the heater 70 and the retainer 40 can be suppressed, so that the retainer 40 can be effectively heated by the heater 70. Further, compared with the case where it is made of metal, by forming the holding member 7A of resin, the cost can be reduced.

[0139] Embodiment 2

[0140] Figure 15 FIG. is a cross-sectional view taken along line B-B' of an inkjet recording head 1 as an example of a "liquid ejection head" according to Embodiment 2 of the present invention. Figure 16 FIG. is a perspective view of a retainer 40 and a heater 70 according to Embodiment 2. Figure 17 FIG. is a cross-sectional view taken along line C-C' of the recording head 1. In addition, the same reference numerals are given to the same components as those in the above-described embodiment, and redundant descriptions are omitted.

[0141] As Figure 15 shown, the recording head 1 of the present embodiment includes a head chip 10, a retainer 40, a fixing plate 60, a heater 70, a retainer cover 80, and a relay substrate 90.

[0142] In the retainer 40, a second flow path 50 is provided. The second flow path 50 includes a first part 51, a second part 52, and a third part 53 in the same manner as in Embodiment 1 described above.

[0143] Further, in the present embodiment, the second part 52 is arranged closer to the upper wall 44 than the head chip 10. Here, the second part 52 being arranged closer to the upper wall 44 than the head chip 10 means that, as Figure 17 shown, in the +Z direction, the center C1 of the second part 52 is arranged closer to the upper wall 44 side than the center C2 between the bottom surface of the recess 47 to which the head chip 10 is fixed and the -Z direction side surface of the upper wall 44. Further, preferably, the minimum thickness h1 in the ±Z direction of the portion of the upper wall 44 of the first member 41 that demarcates the second part 52 is smaller than the maximum height h2 in the ±Z direction of the second part 52.

[0144] The heater 70 is arranged at a position overlapping with a plurality of second parts 52 when viewed from above in the +Z direction. Further, the heater 70 is arranged on the upper wall 44 of the retainer 40. That is, the heater 70 is arranged on the -Z direction side surface of the upper wall 44 of the retainer 40 at a position overlapping with the second part 52 when viewed from above in the +Z direction.

[0145] In the present embodiment, the heater 70 is configured to cover substantially the entire surface on the -Z direction side of the upper wall 44 of the holder 40.

[0146] Such a heater 70 can be a flexible thin film heater, or alternatively, a heater without flexibility.

[0147] In addition, in the heater 70, an opening 75 is provided through which the protrusion 41a of the holder 40, that is, the connection portion 51a of the second flow path 50, is inserted. The connection portion 51a is led out to the -Z direction side compared to the heater 70 via the opening 75.

[0148] Furthermore, in the heater 70, a communication hole 76 communicating with the first wiring insertion hole 49 is provided. The wiring substrate 23 of the head chip 10 is led out to the -Z side via the communication hole 76 of the heater 70.

[0149] In this way, by disposing the heater 70 on the upper wall 44 of the holder 40, the second flow path 50 disposed near the head chip 10 can also be heated by the heater 70. Therefore, the ink that has been sufficiently heated can be supplied to the head chip 10. In addition, since the holder 40 heated by the heater 70 is made of a metal or ceramic with a relatively high thermal conductivity, the ink flowing in the plurality of second flow paths 50 can be sufficiently heated by the heater 70. Even for the head chip 10 disposed at a position separated from the heater 70, the ink that has been sufficiently heated can be supplied. Therefore, the viscosity of the ink ejected from the head chip 10 can be reduced, thereby suppressing a decrease in the ejection characteristics of the ink. Moreover, since the heater 70 is not configured to heat the head chip 10 itself, the structure of the heater 70 and the structure of the recording head 1 can be simplified.

[0150] In addition, in the recording head 1 of the present embodiment, each of the plurality of second flow paths 50 has a "crossing portion", that is, a second portion 52, extending in a direction intersecting the +Z direction as the first direction, and the heater 70 is disposed at a position overlapping the plurality of second portions 52 when viewed from above in the +Z direction.

[0151] In this way, by disposing the heater 70 at a position overlapping the plurality of second portions 52, the length of the flow path heated by the heater 70 can be increased, so that the ink flowing in the second flow path 50 can be effectively heated.

[0152] In addition, although in the present embodiment, the second portion 52 as the "crossing portion" is provided between the first member 41 and the second member 42, it is not particularly limited thereto. It can also be set such that a crossing portion is provided between the second member 42 and the third member 43.

[0153] In addition, although in the present embodiment, one second part 52 as the "crossing part" and one third part 53 as the "connecting part" are respectively provided on each of the plurality of second flow paths 50, it is not particularly limited thereto. It may also be configured such that the second flow path 50 is connected to two or more "first flow paths" by providing a plurality of second parts 52 as the "crossing part" on the second flow path 50. That is to say, the second flow path 50 may also be a branch flow path for distributing liquid to two or more "first flow paths". In other words, it is not necessary for the number of second flow paths 50 to correspond one-to-one with the number of "first flow paths" as in the present embodiment. The holder 40 may also have a structure in which a plurality of second flow paths 50 are connected to at least one of the plurality of "first flow paths" of the plurality of head chips 10 fixed to the holder 40.

[0154] Moreover, it may be configured such that the position where the heater 70 is disposed to overlap with the second part 52 in a top view observed in the +Z direction is not limited to the case where the heater 70 is provided on the upper wall 44 of the holder 40, and the heater 70 may also be provided between the first member 41 and the second member 42 constituting the holder 40, or between the second member 42 and the third member 43. Even when the heater 70 is provided between any of the first member 41, the second member 42, and the third member 43, as long as the heater 70 is disposed at a position overlapping with the second part 52 in a top view observed in the +Z direction, the ink flowing in the second part 52 can be effectively heated by the heater 70. However, compared with the case where the heater 70 is provided between the first member 41 and the second member 42, or between the second member 42 and the third member 43, when the heater 70 is provided on the upper wall 44, it is not necessary to mount the heater 70 between the laminated members constituting the holder 40 during the assembly of the holder 40. Therefore, providing the heater 70 on the upper wall 44 can easily implement the manufacture of the holder 40 or the installation of the heater 70 on the holder 40, and can easily implement the arrangement of the wiring of the heater 70.

[0155] In addition, in the present embodiment, the holder 40 has an upper wall 44 provided on the -Z direction side, which is the second direction opposite to the +Z direction as the first direction, of the holder 40, and the heater 70 is disposed on the upper wall 44. Compared with the case where the heater 70 is disposed on the lower wall 45, by disposing the heater 70 on the upper wall 44, the structure for disposing the heater 70 can be simplified, and thus the arrangement of the wiring of the heater 70 can be easily implemented.

[0156] Moreover, in the present embodiment, the second part 52 as the "crossing part" is disposed closer to the upper wall 44 than the head chip 10. In this way, since the second part 52 as the "crossing part" is disposed near the upper wall 44 where the heater 70 is provided, the ink flowing in the second part 52 can be effectively heated by the heater 70.

[0157] Furthermore, it is more preferably that the minimum thickness h1 in the ±Z direction of the part of the upper wall 44 of the first member 41 that demarcates the second part 52 is less than the maximum height h2 in the ±Z direction of the second part 52. In this way, by making the minimum thickness h1 in the ±Z direction of the part of the upper wall 44 of the first member 41 that demarcates the second part 52 less than the maximum height h2 in the ±Z direction of the second part 52, the second part 52 can be made closer to the heater 70 provided on the -Z direction side surface of the upper wall 44, so that the ink flowing in the second part 52 can be easily heated by the heater 70.

[0158] In addition, although in the present embodiment, the heater 70 is provided only on the upper wall 44, it is not particularly limited thereto. Here, with reference to Figure 18 and Figure 19 , a modified example of the heater 70 will be described. In addition, Figure 18 is a cross-sectional view of the recording head 1. Figure 19 is a perspective view of the holder 40 and the heater 70.

[0159] As Figure 18 and Figure 19 shown, the holder 40 has side walls. The side walls refer to one side of the outer peripheral wall 46.

[0160] The heater 70 is composed of a flexible thin film heater. The heater 70 includes a main body portion 77 provided on the upper wall 44, bent portions 78 provided on the side walls on both sides in the ±X direction, and bent portions 79 provided on the side walls on both sides in the ±Y direction. The bent portions 78 and 79 are portions bent at the end of the upper wall 44 with respect to the main body portion 77, and the main body portion 77 and the bent portions 78 and 79 are integrally provided.

[0161] In this way, by integrally providing the heater 70 on the upper wall 44 and the side walls of the holder 40, it is possible to suppress the occurrence of temperature deviation in the overall temperature of the holder 40 and perform heating. Therefore, it is possible to suppress the occurrence of temperature deviation in the ink flowing in the plurality of second flow paths 50 heated by the heater 70.

[0162] In addition, although in this embodiment, the bent portions 78 are provided on both side surfaces in the ±X directions, and the bent portions 79 are provided on both side surfaces in the ±Y directions, it is not particularly limited thereto, and it may be configured to provide only any one of the bent portion 78 and the bent portion 79. Further, it may be configured to provide only any one of the bent portions 78 provided on the side walls on both sides in the ±X directions, that is, the bent portion 78 provided on the side wall in the +X direction and the bent portion 78 provided on the side wall in the -X direction. Further, it may be configured to provide only any one of the bent portions 79 provided on the side walls on both sides in the ±Y directions, that is, the bent portion 79 provided on the side wall in the +Y direction and the bent portion 79 provided on the side wall in the -Y direction.

[0163] As described above, in the recording head 1 of this embodiment, the holder 40 has side walls, the heater 70 is a flexible thin film heater, and has a main body portion 77 fixed to the upper wall 44, and bent portions 78 and 79 that are bent at the end of the upper wall 44 with respect to the main body portion 77 and fixed to the side walls.

[0164] In this way, by integrally providing the heater 70 on the upper wall 44 and the side walls of the holder 40, it is possible to suppress the occurrence of deviation in the temperature of the entire holder 40 by the heater 70 and perform heating. Therefore, it is possible to suppress the occurrence of deviation in the temperature of the ink flowing in the plurality of second flow paths 50 heated by the heater 70. In addition, since the bent portions 78 and 79 fixed to the side walls can be formed by bending only at the end of the upper wall 44 with respect to the main body portion 77 of the heater 70, it is possible to effectively heat the second flow paths 50 with a simple thin film heater structure.

[0165] In addition, in the recording head 1 of the present embodiment, preferably, each of the plurality of second flow paths 50 has a connecting portion 51a that protrudes from the upper wall 44 of the holder 40 in the "second direction", which is the -Z direction opposite to the +Z direction, and the heater 70 has a plurality of openings, namely, opening portions 75, through which the respective connecting portions 51a of the plurality of connecting portions 51a are inserted. Thus, even if the connecting portion 51a has a structure that protrudes from the upper wall 44 of the holder 40 in the -Z direction, since the opening portions 75 corresponding to the connecting portion 51a are provided in the heater 70, the heater 70 can be easily mounted in the holder 40. In addition, since the opening portions 75 are provided in the heater 70, the heater 70 can be disposed near the connecting portion 51a and the second flow path 50 communicating with the connecting portion 51a, such as the first portion 51 or the second portion 52. Therefore, the heating performed by the heater 70 can be effectively carried out. Incidentally, although a structure in which the heater 70 is divided into a plurality of parts and disposed on the upper wall 44 so as to avoid the connecting portion 51a without providing the opening portions 75 in the heater 70 is also considered, in this case, the number of components such as the heater 70 may increase, resulting in a complicated structure.

[0166] Other embodiments

[0167] As described above, although the respective embodiments of the present invention have been described, the basic structure of the present invention is not limited to the above content.

[0168] Although in the above respective embodiments, as the "first flow path" provided in the head housing 13, for example, the ink introduction port 32 and the introduction liquid chamber 31 that supply ink into the head chip 10 are exemplified, it is not particularly limited thereto. As the "first flow path", the head chip 10 may also include a discharge channel that discharges ink from the head chip 10 to the outside, a circulation channel that circulates ink between the head chip 10 and the liquid container 3, and the like. Similarly, although in the above respective embodiments, as the second flow path 50 of the holder 40, a flow path that supplies ink to the head chip 10 is exemplified, it is not particularly limited thereto. As the second flow path 50, the holder 40 may also include a discharge channel that further discharges the ink discharged from the head chip 10 to the outside, a circulation channel that circulates ink between the head chip 10 and the liquid container 3, and the like.

[0169] For example, although in each of the above-described embodiments, the holder 40 is exemplified as a device composed of three components, i.e., the first component 41, the second component 42, and the third component 43, it is not particularly limited thereto. The holder 40 may be a device composed of a single component or a device composed of two or more components. In addition, the stacking direction of the plurality of components constituting the holder 40 is not limited to the +Z direction, and may be stacked in the +X direction, the +Y direction, or the like. However, when the second part 52 serving as the "crossing part" is provided in the second flow path 50, it is preferable to stack the plurality of components in the +Z direction because the second part 52 is easily formed in this way.

[0170] In addition, the energy generating element of the head chip 10 is not limited to the piezoelectric actuator 18, and various well-known structures can be adopted. For example, as the energy generating element for causing a pressure change in the ink in the pressure chamber 19, for example, a device that changes the volume of the flow path by the deformation of a piezoelectric actuator having a piezoelectric material exhibiting an electromechanical conversion function and causes a pressure change in the ink in the flow path to eject the ink from the nozzle 11 can be used. In addition, as the energy generating element, a device that ejects ink droplets from the nozzle 11 by generating foam due to the heat of a heating element disposed in the flow path can be used. Moreover, as the energy generating element, a so-called electrostatic actuator that generates an electrostatic force between a diaphragm and an electrode and deforms the diaphragm by the electrostatic force to eject ink droplets from the nozzle 11 can be used.

[0171] In addition, although in each of the above-described embodiments, the arrangement direction of the nozzles 11 is exemplified as the +X direction that is the same as the conveyance direction of the medium S, it is not particularly limited thereto. For example, as Figure 20 shown, the arrangement direction of the nozzles 11 may be inclined with respect to the +X direction that is the conveyance direction of the medium S.

[0172] In addition, although in each of the above-described embodiments, the structure in which a plurality of head chips 10 are arranged in the +Y direction with the positions in the +X direction being the same is exemplified, it is not particularly limited thereto. For example, as Figure 21As shown, multiple head chips 10 can also be arranged in a zigzag pattern along the +X direction. Here, arranging the multiple head chips 10 in a zigzag pattern along the +X direction means arranging the head chips 10 arranged in the +X direction alternately offset in the Y direction. That is, the columns of the head chips 10 arranged in the +X direction are arranged in two columns in the +Y direction, and the columns of two head chips 10 are arranged offset by half a pitch in the +X direction. In this way, by arranging the head chips 10 in a zigzag pattern along the +X direction, the nozzle 11 portions of two head chips 10 can be repeated, thereby forming a continuous column of nozzles 11 spanning the +X direction.

[0173] In addition, for example, in a head module having a plurality of recording heads 1 in which the heater 70 is not provided in the above-described Embodiment 1 and Embodiment 2, and a holding member that holds the plurality of recording heads 1 and supplies ink to the plurality of recording heads, such as a branch flow path, if the recording head 1 is rephrased as a head chip and the holding member is rephrased as a holder, the present invention can also be applied to the head module. That is, in the head module, it is only necessary to provide a heater in the holding member corresponding to the holder.

[0174] In addition, although in each of the above-described embodiments, the protrusion 41a is provided so as to protrude from the upper wall 44, it may also be configured to protrude from the side wall.

[0175] In addition, although in the above-described inkjet recording apparatus I, an apparatus in which the recording head 1 is mounted on the holding member 7 and moves in the ±Y direction as the main scanning direction is illustrated, it is not particularly limited thereto. For example, the present invention can also be applied to a so-called line printer in which a plurality of recording heads 1 are arranged and fixed on a unit substrate in a direction orthogonal to the conveyance direction of the medium S, and printing is performed only by moving the medium S in the conveyance direction. In this case, if the recording head 1 is rephrased as a head chip, the flow path structure for distributing liquid to the plurality of recording heads 1 is rephrased as a holder, and the unit substrate is rephrased as a holding member, the present invention can be applied by providing a heater on the flow path structure corresponding to the holder. Of course, if each recording head 1 has a structure including a plurality of head chips, the present invention can also be applied to each recording head 1.

[0176] In addition, although in the above-described embodiments, an inkjet recording head is cited as an example of the liquid ejection device, and an inkjet recording head is cited as an example of the liquid ejection head and they are described, the present invention is broadly directed to all liquid ejection heads and liquid ejection devices, and can of course be applied to liquid ejection heads or liquid ejection devices that eject liquids other than ink. As other liquid ejection heads, for example, various recording heads used in image recording devices such as printers, color material ejection heads used in the manufacture of color filters for liquid crystal displays, etc., electrode material ejection heads used in the formation of electrodes for organic EL (Electro Luminescence) displays, FED (Field Emission Display) displays, etc., and biological organic matter ejection heads used in the manufacture of biochips can be cited, and can also be applied to liquid ejection devices equipped with the liquid ejection heads concerned.

[0177] Symbol Explanation

[0178] I... Inkjet recording device (liquid ejection device); 1... Inkjet recording head (liquid ejection head); 2... Device main body; 3... Liquid container; 4... Conveying mechanism; 4a... Conveying roller; 5... Control unit; 6... Moving mechanism; 7... Holding member; 8... Conveyor belt; 8a... Driving motor; 9... Guide rail; 10... Head chip; 11... Nozzle; 12... Nozzle plate; 13... Outer casing; 14... Communication plate; 15... Pressure chamber forming substrate; 16... Vibration plate; 17... Plastic substrate; 17a... Sealing film; 17b... Fixed substrate; 17c... Opening for fixed substrate; 17d... Plastic part; 18... Piezoelectric actuator; 19... Pressure chamber; 20... First electrode; 21... Piezoelectric body layer; 22... Second electrode; 23... Wiring substrate; 24... Wiring; 25... Driving circuit; 26... Nozzle communication port; 27... Common liquid chamber; 28... Independent communication port; 29... Protection substrate; 30... Holding part; 31... Introducing liquid chamber; 32... Inlet; 33... Wiring insertion through-hole; 40... Holder; 40a - 40d... Corner parts; 41... First component; 41a... Protrusion; 42... Second component; 43... Third component; 43a... Protrusion; 44... Upper wall; 45... Lower wall; 46... Outer peripheral wall; 47... Recess; 48... Partition wall; 49... First wiring insertion through-hole; 50... Second flow path; 51... First part; 51a... Connection part; 52... Second part; 53... Third part; 60... Fixing plate; 61... Exposed opening; 70... Heater; 71... Heating part; 72... Film component; 73... First part; 74... Second part; 75... Opening; 76... Communication hole; 77... Main body part; 78, 79... Bent parts; 80... Holder cover; 81... Storage part; 82... First through-hole; 83... Second wiring insertion through-hole; 84... Head outer wall; 90... Relay substrate; 91... Third wiring insertion through-hole; 92... Second through-hole; S... Medium.

Claims

1. A liquid ejection head, characterized in that, Comprising: A plurality of head chips, each having a nozzle plate and a housing, the nozzle plate having a plurality of nozzles for ejecting liquid in a first direction, and the housing being formed with one or more first flow channels communicating with at least a part of the plurality of nozzles; A holder for fixing the plurality of head chips, configured to include metal or ceramic, and having a plurality of second flow channels communicating with at least one of the one or more first flow channels; A heater for heating the holder, When observed in the first direction, the heater overlaps all of the plurality of head chips.

2. The liquid ejecting head according to claim 1, wherein The housing is made of resin.

3. A liquid ejection head, characterized in that, Comprising: A plurality of head chips, each having a nozzle plate and a housing, the nozzle plate having a plurality of nozzles for ejecting liquid in a first direction, and the housing being formed with one or more first flow channels communicating with at least a part of the plurality of nozzles; A holder for fixing the plurality of head chips, configured to include metal or ceramic, and having a plurality of second flow channels communicating with at least one of the one or more first flow channels; A heater for heating the holder, When observed from above, the heater surrounds all of the plurality of second flow channels, and when observed in a direction orthogonal to the first direction, the heater overlaps at least a part of the second flow channels.

4. A liquid ejection head, characterized in that, Comprising: A plurality of head chips, each having a nozzle plate and a housing, the nozzle plate having a plurality of nozzles for ejecting liquid in a first direction, and the housing being formed with one or more first flow channels communicating with at least a part of the plurality of nozzles; A holder for fixing the plurality of head chips, configured to include metal or ceramic, and having a plurality of second flow channels communicating with at least one of the one or more first flow channels; A heater for heating the holder, When observed from above, the heater surrounds the plurality of second flow channels, and when observed in a direction orthogonal to the first direction, the heater overlaps at least a part of the second flow channels, The second flow channels have: A cross portion extending in a direction crossing the first direction; A communicating portion extending in the first direction and communicating the cross portion with the first flow channel of the housing, The heater is arranged so as to overlap across the cross portion and the communicating portion when observed in a direction orthogonal to the first direction.

5. A liquid ejection head, characterized in that, Comprising: A plurality of head chips, each having a nozzle plate and a housing, the nozzle plate having a plurality of nozzles for ejecting liquid in a first direction, and the housing being formed with one or more first flow channels communicating with at least a part of the plurality of nozzles; A holder for fixing the plurality of head chips, configured to include metal or ceramic, and having a plurality of second flow channels communicating with at least one of the one or more first flow channels; A heater for heating the holder, The holder has an outer peripheral wall that surrounds the plurality of second flow channels when observed from above, The heater is a flexible thin film heater and is wound so as to cover the entire circumference of the outer peripheral wall when observed from above and is fixed to the outer peripheral wall.

6. The liquid ejection head according to claim 5, wherein: the plurality of head chips are arranged and configured in a third direction orthogonal to the first direction; the heater has: a first portion extending in the third direction; a second portion extending in a direction orthogonal to the first direction and intersecting the third direction; the heat generation amount per unit area of the first portion is greater than the heat generation amount per unit area of the second portion.

7. A liquid ejection head, characterized in that, comprises: a plurality of head chips having a nozzle plate and a housing, the nozzle plate having a plurality of nozzles for ejecting liquid in a first direction, and the housing being formed with one or more first flow paths communicating with at least a part of the plurality of nozzles; a holder that fixes the plurality of head chips and is configured to include metal or ceramic and has a plurality of second flow paths communicating with at least one of the one or more first flow paths; a heater that heats the holder; each of the plurality of second flow paths has an intersection portion extending in a direction intersecting the first direction; the heater is disposed at a position overlapping the plurality of intersection portions when viewed from above in the first direction.

8. The liquid ejection head according to claim 7, wherein: the holder has an upper wall provided on the second direction side of the holder, which is the direction opposite to the first direction; the heater is disposed on the upper wall.

9. The liquid ejection head according to claim 8, wherein: the intersection portion is disposed closer to the upper wall than the head chip.

10. The liquid ejection head according to claim 8 or 9, wherein: the holder has a side wall; the heater is a flexible thin film heater and has: a main body portion fixed to the upper wall; a bent portion bent at an end of the upper wall with respect to the main body portion and fixed to the side wall.

11. The liquid ejection head according to claim 8, wherein: each of the plurality of second flow paths has a connection portion protruding from the upper wall of the holder in the second direction, which is the direction opposite to the first direction; the heater has a plurality of openings, and each of the plurality of connection portions is inserted through a corresponding one of the plurality of openings.

12. The liquid ejection head according to any one of claims 1, 3-5, 7, wherein: a fixing plate is provided, the fixing plate having a plurality of openings for exposing the plurality of nozzles of the head chip and being made of metal; the holder has a lower wall that fixes the plurality of head chips and the fixing plate; the lower wall has a plurality of recesses for receiving each of the plurality of head chips.

13. The liquid ejection head according to any one of claims 1, 3-5, 7, wherein: the liquid is ultraviolet curable ink or solvent-based ink.

14. The liquid ejection head according to any one of claims 1, 3-5, 7, wherein: a head outer wall is provided, and the head outer wall is disposed so as to be separated from the holder by the heater. The heat conductivity of the outer wall of the head is lower than that of the retainer.

15. A liquid ejection device, characterized in that, Comprising: The liquid ejection head according to claim 14; A holding member that holds the liquid ejection head and is made of metal, A part of the holding member is arranged so as to be separated from the heater by the outer wall of the head.

16. A liquid ejection device, characterized in that, Comprising: The liquid ejection head according to claim 14; A holding member that holds the liquid ejection head and is made of resin, A part of the holding member is arranged so as to be separated from the heater by the outer wall of the head.

17. A liquid ejection device, characterized in that, Comprising: The liquid ejection head according to any one of claims 1 to 13; A holding member that holds the liquid ejection head and is made of resin, A part of the holding member is arranged so as to be separated from the retainer by the heater.

18. A liquid ejection device, characterized in that, Comprising: The liquid ejection head according to any one of claims 1 to 14; A control device that controls the heater.

19. A liquid ejection device, characterized in that, Comprising: The liquid ejection head according to any one of claims 1 to 14; A liquid container that stores the liquid ejected from the liquid ejection head.

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