Liquid ejection head

Abstract

A liquid ejection head (6) has an upstream-side common flow path (74) (common flow path) and a heat generating member (50). The upstream-side common flow path (74) has a first common flow path (74A) that communicates with a plurality of pressure chambers that respectively communicate with a plurality of nozzles arranged along an arrangement direction (X direction) and extends along the arrangement direction from one end side to the other end side of the plurality of nozzles along the arrangement direction, a liquid inflow path (74B) that communicates with a central portion of the arrangement direction of the first common flow path (74A), and liquid discharge paths (74C) (liquid discharge path 74C1, liquid discharge path 74C2) that respectively communicate with both end portions of the arrangement direction of the first common flow path (74A). The heat generating member (50) is provided so as to be capable of heating the upstream-side common flow path (74) and extends along the arrangement direction.

Description

Technical Field

[0001] Embodiments of the present invention relate to liquid ejection heads. Background Technology

[0002] In recent years, the demand for high-viscosity inks has increased in the printing industry. Structures have been disclosed that reduce the viscosity of high-viscosity inks by heating them in order to eject them from a nozzle. For example, a structure is disclosed that supplies heat from the heater to the liquid flowing in the common supply flow path by mounting a heater on one side of a common supply flow path forming member (see, for example, Patent Document 1).

[0003] However, in the existing technology, it is not possible to sufficiently reduce the viscosity of the liquid to which the ink or other ejected object is applied, and sometimes the ejection characteristics are reduced.

[0004] Existing technical documents Patent documents Patent Document 1: Japanese Patent Application Publication No. 2010-241100 Summary of the Invention

[0005] The liquid nozzle of this embodiment includes a common flow path and a heating element. The common flow path includes: a first common flow path communicating with a plurality of pressure chambers and extending along the arrangement direction from one end to the other of a plurality of nozzles arranged along the arrangement direction, the plurality of pressure chambers respectively communicating with the plurality of nozzles; a liquid inflow path communicating with the central portion of the first common flow path along the arrangement direction; and a liquid discharge path communicating with both ends of the first common flow path along the arrangement direction. The heating element is configured to heat the common flow path and extends along the arrangement direction. Attached Figure Description

[0006] Figure 1 This is a schematic diagram of the liquid ejection device of this embodiment.

[0007] Figure 2 It is an exploded three-dimensional view showing the overall structure of the liquid ejector head.

[0008] Figure 3 This is a cross-sectional view of an example of a liquid ejector head.

[0009] Figure 4 This is a detailed diagram of the liquid nozzle, including the upstream shared flow path and the heating element.

[0010] Figure 5A This is a detailed diagram of the liquid ejector head, including the upstream shared flow path and the heating element.

[0011] Figure 5B This is a detailed diagram of the heating element.

[0012] Figure 6 This is an explanatory diagram of the wiring pattern of the heating wires of the heating element.

[0013] Figure 7A This is a schematic diagram of an example of a heating element.

[0014] Figure 7B This is a schematic diagram of an example of a heating element.

[0015] Figure 8A This is a schematic diagram of the heating element.

[0016] Figure 8B This is a 3D view of the heating element.

[0017] Figure 8C This is a cross-sectional view of the heating element.

[0018] Figure 8D This is a magnified schematic diagram of a local area.

[0019] Figure 8E This is an enlarged schematic diagram of the bent area of ​​the heating element.

[0020] Figure 9A This is an explanatory diagram of the flow path shared by the heating component and the upstream side.

[0021] Figure 9B This is a schematic diagram of the shared flow path between the heating component and the upstream side.

[0022] Figure 10 This is a schematic diagram of the cross-section of the liquid ejector head.

[0023] Explanation of reference numerals in the attached figures 6, 9 Liquid ejector heads 72 shared flow path 74 and 75 share a common flow path on the upstream side. 74A, 75A 1st common flow path 74B, 75B Liquid Inflow Path Liquid discharge paths for 74C, 74C1, 74C2, and 75C. 50, 51 Heating components Detailed Implementation

[0024] The purpose of this invention is to provide a liquid ejection head that can improve ejection characteristics.

[0025] Hereinafter, embodiments of the liquid ejection device will be described in detail with reference to the accompanying drawings. However, sometimes unnecessary detailed descriptions are omitted. For example, detailed descriptions of matters already known or repeated descriptions of substantially the same structures are sometimes omitted. This is to avoid making the following description unnecessarily lengthy and to facilitate understanding by those skilled in the art.

[0026] Furthermore, the accompanying drawings and the following description are provided to enable those skilled in the art to fully understand this disclosure, and are not intended to limit the subject matter of the claims.

[0027] (First Embodiment) Figure 1 This is a schematic diagram of an example of the liquid ejection device 1 of this embodiment. Figure 1 This diagram shows a planar view of the liquid ejection device 1. In this embodiment, the long side direction of the liquid ejection device 1 is designated as the Y direction, the short side direction as the X direction, and the direction perpendicular to both the X and Y directions as the Z direction. Furthermore, in this embodiment, the X, Y, and Z directions are explained along both sides of each direction. Additionally, when a "+" is marked before each direction, it indicates the direction along the arrow shown in the diagram; when a "-" is marked, it indicates the opposite direction of the arrow shown in the diagram.

[0028] The liquid ejection device 1 includes a base 2, a guide 3, a conveyor 4, a frame 5, a liquid ejection head 6, and a drive unit 8.

[0029] The base 2 is composed of a cuboid with a planar shape having a longer rectangle in the scanning direction of the liquid ejection head 6.

[0030] The guide 3 is a component that guides the transport stage 4. It is a component that extends along the long side (Y direction) of the base 2 and is fixed to the upper surface of the base 2. As an example, the guide 3 is composed of a cuboid-shaped component with a rectangular cross-section orthogonal to the scanning direction (Y direction).

[0031] The transport stage 4 is a platform for transporting the object 7. The transport stage 4 has a rectangular shape, and its lower surface (the +Z side surface) contacts the guide 3. The transport stage 4 is guided by the guide 3 and transported in the scanning direction of the base 2. The object 7 is placed on the transport stage 4. The object 7 is an object from which liquid is ejected from the liquid ejector head 6. The object 7 is, for example, a substrate, paper, etc.

[0032] The frame 5 is a support component with a gate-shaped design that supports the liquid nozzle 6. The frame 5 is fixed to a predetermined position, such as the middle position, of the base 2 in the XY plane in a manner that spans the short side direction (X direction) of the base 2.

[0033] The liquid ejector head 6 is a head in which multiple nozzles are arranged along an arrangement direction (X direction) and used to eject liquid from the nozzles by inkjet printing. The liquid is, for example, ink. In this embodiment, the case where the liquid is ink will be described. However, the liquid is not limited to ink.

[0034] The liquid nozzle 6 is supported on the frame 5. The liquid nozzle 6 sprays ink onto the object 7 at a timed interval as the object 7 passes below it. This coats the object 7 with ink. Figure 1 In the example shown, two liquid nozzles 6 are respectively arranged on both sides of the frame 5. However, it is also possible to arrange only one liquid nozzle 6 on the frame 5, or to arrange two frames 5, with liquid nozzles 6 arranged on both sides of each frame 5. The number and arrangement of liquid nozzles 6 can be changed according to the processing to be performed on the object 7 by the liquid nozzles 6.

[0035] The drive unit 8 drives the transport stage 4 in the scanning direction. Figure 1 In the example shown, at least one drive unit 8 is disposed on the base 2 along the scanning direction and connected to the transport stage 4. This structure enables the drive unit 8 to support the transport stage 4 for transport drive in the scanning direction. Figure 1 As an example, this illustration shows two drive units 8 extending in the scanning direction (Y direction) positioned near both ends of the base 2 in the short-side direction (X direction). The drive units 8 are composed of linear motors, ball screws connected to rotary motors, etc. Figure 1 The example shown is a method of using a linear motor as the drive unit 8.

[0036] like Figure 1 As shown, when the liquid nozzle 6 is arranged to cover the entire width of the liquid ejection device 1 in the X direction, the liquid nozzle 6 can apply ink to the object 7 in one pass. In this case, the liquid ejection device 1 can efficiently print a large number of printed materials. On the other hand, sometimes the liquid nozzle 6 is not arranged to cover the entire width of the liquid ejection device 1 in the X direction. In this case, the liquid ejection device 1 performs printing in a multi-scan mode. In multi-scan printing, the liquid nozzle 6 prints multiple rows repeatedly on the object 7. Therefore, the liquid ejection device 1 can precisely print specific areas, suppress ink waste, and reduce costs. Such multi-scan printing is sometimes called swath coating.

[0037] Next, the overall structure of the liquid ejector head 6 will be explained.

[0038] Figure 2 This is an exploded perspective view showing the overall structure of the liquid ejector head 6.

[0039] Figure 2 The XYZ directions in Figure 1 Same. Figure 2 In the diagram, the -Z direction is the ejection direction of ink from the liquid ejector head 6. The X direction is the direction of the long side of the liquid ejector head 6. The X direction, which is the direction of the long side of the liquid ejector head 6, is consistent with the arrangement direction of the nozzles. The Y direction is the width direction of the liquid ejector head 6. The Z direction is consistent with the stacking direction of the plates that are the constituent elements of the liquid ejector head 6.

[0040] The liquid ejector head 6 has a housing part 10, a vibrating plate 20, a flow path plate 30, a nozzle plate 40, a heating element 50, and a base part 60.

[0041] The base portion 60 is composed of a pressure-variable part 61 such as PZT, a flexible printed circuit board 63, and a base 62. The pressure-variable part 61 is provided at the lower end side (downstream side in the -Z direction) of the base portion 60. The upper part (downstream side in the +Z direction) of the housing portion 10 is opened, and the heating element 50 and the base portion 60 are housed in the housing portion 10 through the opening.

[0042] A flow path section 70 is provided on the lower surface side (downstream end face in the -Z direction) of the housing section 10, with the vibrating plate 20 in between. The flow path section 70 includes a flow path plate 30 and a nozzle plate 40. The nozzle plate 40, the flow path plate 30, and the vibrating plate 20 are stacked in sequence and fixed to each other.

[0043] On the nozzle plate 40, multiple nozzles 41 are arranged along the arrangement direction (X direction). Figure 2 As an example, a nozzle array consisting of multiple nozzles 41 arranged along the arrangement direction (X direction) is shown in which multiple pairs are arranged in a manner that they are spaced apart in the X direction and spaced apart in the Y direction.

[0044] The nozzle plate 40 and the flow path plate 30, the flow path plate 30 and the vibrating plate 20, the vibrating plate 20 and the housing part 10, the heating element 50 and the housing part 10, the vibrating plate 20 and the pressure regulating part 61, the base part 60 and the vibrating plate 20, and the base 62 and the pressure regulating part 61 are respectively fixed by adhesives or the like. For example, an epoxy-based adhesive with thermosetting properties is used. Furthermore, the same adhesive or different adhesives can be used as the adhesive for joining the various components. For example, a combination of rubber-based adhesives and epoxy-based adhesives can also be used.

[0045] Figure 3 This is a cross-sectional view of an example of a liquid ejector head 6.

[0046] Figure 3 A cross-sectional view showing the vicinity of the nozzle 41 in the liquid ejector head 6, where ink is ejected. Figure 3The sectional view shown is equivalent to... Figure 2 The exploded perspective view shows the B-B' cross-sectional view of the liquid ejector head 6 in its assembled state.

[0047] exist Figure 3 As an example, the following arrangement is shown: an upstream common flow path 74 is arranged in the center of the liquid nozzle 6 in the Y direction, and a pressure chamber 33, a nozzle 41, and a downstream common flow path 76 are arranged in the left and right directions (+Y direction and -Y direction) along the Y direction with the upstream common flow path 74 as the center.

[0048] If used Figure 2 As explained, a plurality of nozzles 41 are arranged throughout the nozzle plate 40 in the arrangement direction (X direction) of the nozzles 41. Figure 3 The image shows nozzles 41 in a pair of nozzle rows arranged with gaps between them in the Y direction, comprising multiple nozzles 41. The nozzle plate 40 is formed, for example, by etching and stamping a 100 μm thick stainless steel plate.

[0049] The flow path plate 30 is a plate that constitutes at least a portion of the common flow path 72 (described later) that forms the flow path for the liquid. The flow path plate 30 is formed in a cuboid shape. The flow path plate 30 is formed, for example, by stacking stainless steel plate components with a thickness of 10 to 100 μm, which are formed by etching and stamping. The number of layers is, for example, 3 to 10 layers.

[0050] The flow path plate 30 has a pressure chamber 33 that is connected one-to-one with each of the plurality of nozzles 41, and a silo section 36 that connects the pressure chamber 33 with the nozzles 41.

[0051] The pressure chamber 33 is a space for ejecting ink stored inside from the nozzle 41 by applying pressure from the pressure regulating unit 61. The pressure chamber 33 is connected to a plurality of nozzles 41 arranged along the arrangement direction (X direction) of the nozzles 41. The pressure chamber 33 is formed in the shape of a cuboid, and the upper wall forming the upper side (+Z direction end face) is formed by a vibrating plate 20. The pressure chamber 33 may also not be a cuboid and may have multiple steps inside.

[0052] The silo section 36 is connected to the pressure chamber 33 and the nozzle 41 in the Z direction.

[0053] The flow path plate 30 has an upstream individual flow path 32 that communicates one-to-one with each of the plurality of pressure chambers 33, and an upstream common flow path 74 that communicates with the plurality of upstream individual flow path sections 32. In addition, the flow path plate 30 has a downstream individual flow path 34 that communicates one-to-one with each of the plurality of pressure chambers 33, and a downstream common flow path 76 that communicates with the plurality of downstream individual flow path sections 34.

[0054] The vibrating plate 20 is a plate used to propagate vibrations caused by pressure fluctuations generated by the pressure fluctuation unit 61 into the pressure chamber 33. The vibrating plate 20 is, for example, a thin film with a thickness of 5 to 50 μm, formed of, for example, Ni. A portion of the vibrating plate 20 forms the wall surface of the pressure chamber 33 in the Z direction. An opening is provided on the vibrating plate 20 to form a portion of the upstream common flow path 74 and the downstream common flow path 76.

[0055] The housing portion 10 is the frame of the liquid ejector head 6. The housing portion 10 is, for example, formed into a cuboid shape. The housing portion 10 is formed by machining alloy steel such as stainless steel. The thickness of the housing portion 10 in the Z direction is, for example, about 1 cm.

[0056] The housing portion 10 is provided with a space that forms part of the upstream shared flow path 74 and the downstream shared flow path 76. The flow path plate 30, the vibrating plate 20, and these spaces and openings in the housing portion 10 constitute a pressure chamber 33, a downstream individual flow path 34 communicating with the pressure chamber 33, and a downstream shared flow path 76 communicating with the pressure chamber 33 via the downstream individual flow path 34. Furthermore, the flow path plate 30, the vibrating plate 20, and these spaces and openings in the housing portion 10 constitute a pressure chamber 33, an upstream individual flow path 32 communicating with the pressure chamber 33, and an upstream shared flow path 74 communicating with the pressure chamber 33 via the upstream individual flow path 32.

[0057] The upstream shared flow path 74 and the downstream shared flow path 76 are examples of the shared flow path 72. The shared flow path 72 is a flow path that is connected directly or via other separate flow paths (upstream separate flow path section 32, downstream separate flow path section 34, etc.) to multiple pressure chambers 33 that are respectively connected to multiple nozzles 41 arranged along the arrangement direction (arrow X direction), and is provided for these multiple pressure chambers 33.

[0058] Furthermore, the housing portion 10 has a liquid inflow path for introducing ink from the outside and a liquid discharge path for discharging ink from the outside (in... Figure 3 (Illustration omitted).

[0059] Ink supplied to the upstream common flow path 74 via the liquid inflow path flows sequentially through the upstream individual flow path 32, the pressure chamber 33, the downstream individual flow path 34, and the downstream common flow path 76, and is discharged from the liquid discharge path. Furthermore, the ink discharged from the liquid discharge path is supplied back to the upstream common flow path 74 via the liquid inflow path through the ink storage section and a pump. In other words, the liquid ejector head 6 of this embodiment is configured as a circulation structure for ink circulation.

[0060] The pressure regulating unit 61 is disposed inside the housing 10 and imparts pressure variation to the ink in the pressure chamber 33 via the vibrating plate 20. The pressure variation imparted by the pressure regulating unit 61 propagates towards the nozzle 41 within the pressure chamber 33, thereby ejecting ink from the nozzle 41.

[0061] The pressure regulating section 61 is composed of a piezoelectric element. Specifically, the pressure regulating section 61 has a drive section (not shown), which is driven by inserting electrodes into the flexible printed circuit board 63 within the piezoelectric element and providing electrical signals to the electrodes. The drive section is separated into multiple channels through slits corresponding one-to-one with the nozzle 41. The pressure regulating section 61 is supported by the base 62 of the base section 60 (see also...). Figure 2 The base 62 of the base portion 60 can also be referred to as a support for the pressure regulating portion 61. Furthermore, a flexible printed circuit board 63, serving as a control substrate for controlling the piezoelectric element of the pressure regulating portion 61, is mounted on the base 62 of the base portion 60. The flexible printed circuit board 63 is electrically connected to the pressure regulating portion 61.

[0062] The pressure variation unit 61 is arranged to contact the protrusion of the vibrating plate 20, which forms the upper side wall (+Z direction side) of the pressure chamber 33. The protrusion of the vibrating plate 20... Figure 3 The diagram is omitted. The pressure regulating part 61 deforms by stretching and contracting along the Z direction when a voltage is applied. The pressure regulating part 61 is, for example, a stacked piezoelectric actuator of the D33 mode.

[0063] The pressure regulating section 61 deforms in a manner extending along the Z-direction, pressing the protrusion provided on the vibrating plate 20 toward the nozzle 41 in the -Z direction. This causes the upper sidewall of the pressure chamber 33 (the wall surface on the +Z direction side) to deform, generating pressure fluctuations in the ink within the pressure chamber 33. These pressure fluctuations propagate toward the nozzle 41 via the silo section 36, thereby ejecting ink from the nozzle 41 to the outside. Thus, in the liquid ejection head 6, the ink ejection is controlled by the operation of the pressure regulating section 61.

[0064] In this embodiment, a heating element 50 is provided in the liquid spray head 6.

[0065] The heating element 50 is configured to heat the common flow path 72. In this embodiment, the heating element 50 is configured to heat the upstream common flow path 74, which is an example of the common flow path 72, as an example. Alternatively, the heating element 50 may also be configured to heat both the upstream common flow path 74 and the downstream common flow path 76, which are examples of the common flow path 72.

[0066] The configuration of the heating element 50 is described in detail.

[0067] Figure 4This is a detailed diagram of the liquid ejector head 6, including the upstream common flow path 74 and the heating element 50.

[0068] exist Figure 4 The diagram shows a cross-sectional view of the upstream common flow path 74 and a portion of the heating element 50 in the liquid ejector head 6. Figure 4 The sectional view shown is equivalent to... Figure 2 The exploded perspective view shows the A-A' cross-sectional view of the liquid ejector head 6 in its assembled state.

[0069] In this embodiment, the upstream common flow path 74 includes a first common flow path 74A, a liquid inflow path 74B, and a liquid discharge path 74C.

[0070] The first common flow path 74A communicates with multiple pressure chambers 33 via an upstream separate flow path section 32, and extends from one end to the other end along the arrangement direction (X direction) of the multiple nozzles 41. The multiple pressure chambers 33 are each connected to the multiple nozzles 41 arranged along the arrangement direction (X direction). That is, the first common flow path 74A is a long, narrow flow path provided in the liquid nozzle head 6, extending from one end to the other along the arrangement direction (X direction) of the multiple nozzles 41. Hereinafter, the arrangement direction of the multiple nozzles 41 will sometimes be simply referred to as the arrangement direction. As described above, the arrangement direction is the X direction in the figure.

[0071] Liquid inflow path 74B is an inflow path that allows ink to flow in from the outside. Liquid inflow path 74B is connected to the central part of the first common flow path 74A in this arrangement direction (X direction).

[0072] Liquid discharge path 74C is a discharge path for discharging ink to the outside. In this embodiment, liquid discharge path 74C is connected to both ends of the first common flow path 74A in the arrangement direction (X direction). That is, in this embodiment, liquid discharge path 74C includes liquid discharge path 74C1 and liquid discharge path 74C2. Liquid discharge path 74C1 is connected to one end of the first common flow path 74A in the arrangement direction (X direction). Liquid discharge path 74C2 is connected to the other end of the first common flow path 74A in the arrangement direction (X direction).

[0073] The heating element 50 is configured to heat the upstream common flow path 74 and extends along the arrangement direction (X direction) of the nozzles 41. That is, the heating element 50 is a strip-shaped element that extends along the long side direction (X direction) of the upstream common flow path 74.

[0074] In detail, the positions of one end of the liquid discharge path 74C side of the heating element 50 in the long side direction (i.e., the arrangement direction (X direction)) and one end of the liquid discharge path 74C side of the first common flow path 74A in the long side direction (i.e., the arrangement direction (X direction)) in the X direction can be the same, or substantially the same, or substantially the same. That is, for example, one end of the liquid discharge path 74C side of the heating element 50 in the long side direction (i.e., the arrangement direction (X direction)) can also be configured to heat one end of the liquid discharge path 74C side of the first common flow path 74A in the long side direction (i.e., the arrangement direction (X direction)).

[0075] Furthermore, the positions of one end of the heating element 50 along the liquid inflow path 74B in the long side direction (X direction) and one end of the first common flow path 74A along the liquid inflow path 74B in the long side direction (X direction) can be the same or approximately the same in the X direction. That is, for example, one end of the heating element 50 along the liquid inflow path 74B in the long side direction (X direction) can also be configured to heat one end of the first common flow path 74A along the liquid inflow path 74B in the long side direction (X direction).

[0076] In detail, one end of the heating element 50 along the liquid discharge path 74C in the long side direction (X direction) is at the same, approximately the same, or substantially the same position in the X direction as one end of the first common flow path 74A along the liquid discharge path 74C in the long side direction (X direction). Therefore, one end of the heating element 50 along the liquid discharge path 74C in the long side direction (X direction) is configured to heat one end of the first common flow path 74A along the liquid discharge path 74C in the long side direction (X direction).

[0077] Furthermore, one end of the heating element 50 along the liquid inflow path 74B in the long side direction (X direction) is at the same or approximately the same position in the X direction as one end of the first common flow path 74A along the liquid inflow path 74B in the long side direction (X direction). Therefore, one end of the heating element 50 along the liquid inflow path 74B in the long side direction (X direction) is configured to heat one end of the first common flow path 74A along the liquid inflow path 74B in the long side direction (X direction).

[0078] Furthermore, the long side direction (X direction) of the heating element 50 extends in the same direction as the long side direction (X direction) of the first common flow path 74A and the arrangement direction (X direction) of the nozzles 41. Therefore, the heating element 50 is configured to continuously heat the ink flowing in the first common flow path 74A along the arrangement direction (X direction) of the nozzles 41, covering the entire area of ​​the first common flow path 74A from one end to the other in the long side direction (X direction).

[0079] The heating element 50 can be any component capable of applying heat to the liquid within the upstream common flow path 74 by means of heating. For example, the heating element 50 is an electric heating wire that is heated by an applied power source, but it is not limited to this.

[0080] As described above, in this embodiment, the upstream common flow path 74 is composed of a first common flow path 74A, a liquid inflow path 74B that is connected to the central part of the arrangement direction (X direction) of the first common flow path 74A, and liquid discharge paths 74C (liquid discharge path 74C1 and liquid discharge path 74C2) that are connected to both ends of the arrangement direction (X direction) of the first common flow path 74A.

[0081] Therefore, as Figure 4 As shown, the heating element 50 is preferably composed of a first heating element 50A and a second heating element 50B extending along the arrangement direction. The first heating element 50A and the second heating element 50B are arranged such that they sandwich the liquid inflow path 74B from opposite directions in the arrangement direction (X direction).

[0082] If power is supplied to each part of the liquid ejection device 1, ink is supplied from outside the upstream common flow path 74 to the liquid inflow path 74B by driving the pump (not shown in the figure).

[0083] Liquid supplied from the outside to the liquid inflow path 74B (referring to the Za direction) flows into the central part of the first common flow path 74A, which serves as the connection point between the liquid inflow path 74B and the first common flow path 74A, in the arrangement direction (X direction). From the central part, it branches to the left and right (referring to the arrows Xa and Xb directions) along the arrangement direction (X direction), and is discharged from the liquid discharge paths 74C (liquid discharge path 74C1 and liquid discharge path 74C2), which are respectively connected to the two ends of the first common flow path 74A in the arrangement direction (X direction), respectively (referring to the arrow Zb direction).

[0084] The heating element 50 is configured to heat the upstream common flow path 74 and extends along the arrangement direction (X direction) of the nozzles 41, i.e., the extension direction of the first common flow path 74A. Therefore, the ink flowing within the first common flow path 74A extending along the arrangement direction (X direction) of the nozzles 41 is heated by the heating element 50 extending along this arrangement direction (X direction). That is, the ink supplied from the liquid inflow path 74B to the first common flow path 74A branches in opposite directions at the central portion of the first common flow path 74A in the arrangement direction (X direction), and is continuously heated by the heating element 50 while flowing from this central portion toward both ends. Therefore, the ink flowing into the first common flow path 74A, while maintaining a low viscosity due to heating by the heating element 50, flows along the arrangement direction (X direction) and is supplied to each of the plurality of nozzles 41 via each of the plurality of pressure chambers 33 arranged along the arrangement direction (X direction).

[0085] As described above, the liquid ejector head 6 of this embodiment includes a common flow path 72 (upstream side common flow path 74) and a heating element 50.

[0086] The upstream common flow path 74 (common flow path 72) includes: a first common flow path 74A, which communicates with a plurality of pressure chambers 33 and extends along the arrangement direction from one end to the other end of a plurality of nozzles 41, the plurality of pressure chambers 33 being respectively communicated with a plurality of nozzles 41 arranged along the arrangement direction (X direction); a liquid inflow path 74B, which communicates with the central portion of the first common flow path 74A in the arrangement direction; and a liquid discharge path 74C (liquid discharge path 74C1, liquid discharge path 74C2), which communicates with both ends of the first common flow path 74A in the arrangement direction. A heating element 50 is configured to heat the upstream common flow path 74 (common flow path 72) and extends along the arrangement direction.

[0087] Thus, in the liquid ejector head 6 of this embodiment, the upstream common flow path 74 is composed of a first common flow path 74A, a liquid inflow path 74B communicating with the central portion of the first common flow path 74A in the arrangement direction (X direction), and liquid discharge paths 74C (liquid discharge path 74C1 and liquid discharge path 74C2) communicating with both ends of the first common flow path 74A in the arrangement direction (X direction). Therefore, the ink flowing in from the liquid inflow path 74B flows into the central portion of the first common flow path 74A and is discharged from both ends of the first common flow path 74A.

[0088] Therefore, in the liquid ejector head 6 of this embodiment, compared to a structure where ink flows in from one end of the long side direction (X direction) of the first common flow path 74A and is discharged from the other end of the same direction (X direction) (hereinafter, sometimes referred to as other structure A), the distance from the ink inlet to the outlet in the first common flow path 74A is shortened. Specifically, in the case of other structure A, the distance from the ink inlet to the outlet in the first common flow path 74A is a distance L10 (refer to...). Figure 4 On the other hand, in the liquid ejector head 6 of this embodiment, the distances from the ink inlet to the outlet in the first common flow path 74A are approximately half of the distance L10, namely distance L1 and distance L2 (see reference). Figure 4 ).

[0089] In the liquid ejector head 6 of this embodiment, the distance from the ink inlet to the outlet in the first common flow path 74A is set to be shorter than that of other structures A. The heat transfer Q from the heating element 50 to the ink in the flow path is expressed by the following formula.

[0090] Q=kA(T1-T2) / L…Formula (1) In equation (1), k represents thermal conductivity, A represents the cross-sectional area of ​​the flow path, L represents the length of the flow path, and T1 and T2 represent the temperatures at the ink inlet and outlet, respectively. According to equation (1), by shortening the flow path length L, the heat transfer Q increases, thereby improving the heating efficiency of the ink.

[0091] On the other hand, the amount q that dissipates heat to the surrounding environment per unit time during the ink flow path can be approximated by the following equation (2) according to Newton's law of cooling.

[0092] q=hS(TT) env …Equation (2) In equation (2), h represents thermal conductivity, S represents the surface area that helps dissipate heat within the flow path, and T represents the ink temperature. env The ambient temperature is represented by q. According to equation (2), it can be said that the longer the ink travels through the flow path, the greater the total heat loss due to heat dissipation and the greater the temperature drop. However, in this embodiment, since the flow path length L is short and the ink travel time is short, the impact of heat dissipation on the flow path wall and the surrounding environment (the cumulative amount of q) is small. Therefore, in the liquid ejector head 6 of this embodiment, the temperature of the heated ink does not drop significantly within the flow path, making it easy to maintain a uniform temperature distribution.

[0093] As described above, the liquid ejector head 6 of this embodiment has a structure that can improve the heating efficiency of the ink (increase of Q in Equation (1)) while suppressing heat loss to the outside (decrease of q in Equation (2)), thereby improving the ink temperature control and liquid ejection performance.

[0094] Therefore, the ink flowing into the first common flow path 74A, while maintaining a low viscosity due to heating by the heating element 50, flows along the arrangement direction (X direction) and is supplied to each of the plurality of nozzles 41 via each of the plurality of pressure chambers 33 arranged along the arrangement direction (X direction). Thus, in the liquid ejection head 6 of this embodiment, high viscosity of the ink can be suppressed, and the ejection characteristics of the ink from the plurality of nozzles 41 arranged along the arrangement direction (X direction) can be improved.

[0095] Therefore, the ejection characteristics can be improved in the liquid ejection head 6 of this embodiment.

[0096] Furthermore, in the liquid ejector head 6 of this embodiment, the heating element 50 is composed of a first heating element 50A and a second heating element 50B extending along the arrangement direction. The first heating element 50A and the second heating element 50B are arranged such that they sandwich the liquid inflow path 74B from opposite directions in the arrangement direction (X direction).

[0097] Here, in order to adjust the temperature of the ink flowing in the first common flow path 74A to the target temperature, it is preferable to heat the liquid at a higher temperature to make the liquid flow into the liquid flow path 74B side of the first common flow path 74A.

[0098] In the liquid ejector head 6 of this embodiment, the first heating element 50A and the second heating element 50B are arranged in a manner that sandwiches the liquid inflow path 74B between mutually opposing positions in the arrangement direction (X direction). This allows for efficient heat supply to the ink flowing in the liquid inflow path 74B, and the structure inserted into the inflow path makes it less susceptible to external heat effects such as heat dissipation, ensuring a stable supply of the required heat output. Therefore, the liquid ejector head 6 of this embodiment does not require a separate preheater, as is typically provided to compensate for insufficient heat output.

[0099] Furthermore, as described above, in this embodiment, the heating element 50 is provided as an example capable of heating the upstream common flow path 74, which is an example of a common flow path 72. However, the heating element 50 may also be configured to heat both the upstream common flow path 74 and the downstream common flow path 76, which are examples of a common flow path 72. In this case, it is sufficient to provide the heating element 50 for the downstream common flow path 76 in the same manner as the heating element 50 provided for the upstream common flow path 74. However, since increasing the ink temperature to reduce viscosity before ink is ejected is more efficient, a structure that heats the upstream common flow path 74 is preferred.

[0100] (Second Implementation) In the above embodiment, the upstream common flow path 74 of the liquid nozzle 6 is described as an example consisting of a long strip-shaped first common flow path 74A extending along the arrangement direction (X direction) of the nozzles 41, a liquid inflow path 74B communicating with the central portion of the first common flow path 74A in the extension direction (X direction), and a liquid discharge path 74C communicating with both ends of the first common flow path 74A in the extension direction (X direction).

[0101] In this embodiment, the upstream common flow path of the liquid nozzle is described as having a structure in which ink flows in from one end of the long side direction (X direction) of the first common flow path and is discharged from the other end of the arrangement direction (X direction), and the heat generation of the heating element is different along the arrangement direction.

[0102] Figure 1 This is a schematic diagram of an example of the liquid ejection device 1B according to this embodiment. The liquid ejection device 1B is the same as the liquid ejection device 1 of the first embodiment described above, except that it has a liquid ejection head 9 instead of a liquid ejection head 6. Furthermore, as... Figure 3 As shown, the liquid nozzle 9 is the same as the liquid nozzle 6 of the above embodiment, except that it has a heating element 51 instead of a heating element 50 and an upstream common flow path 75 instead of an upstream common flow path 74. Specifically, the B-B' cross-section of the liquid nozzle 9 (refer to...) Figure 2 In addition to having a heating element 51 instead of a heating element 50 and an upstream common flow path 75 instead of an upstream common flow path 74, the B-B' cross section (refer to the liquid ejector head 6 in the above embodiment) is similar to that in the above embodiment. Figure 2 )same.

[0103] Similar to the heating element 50 in the above embodiment, the heating element 51 is configured to heat the common flow path 72. In this embodiment, the heating element 51 is described as being configured to heat the upstream common flow path 75, which is an example of the common flow path 72. Alternatively, the heating element 51 may also be configured to heat both the upstream common flow path 75 and the downstream common flow path 76, which are examples of the common flow path 72.

[0104] The common flow path 75 and the heating element 51 located on the upstream side of the liquid nozzle 9 in this embodiment will be described in detail.

[0105] Figure 5A This is a detailed diagram illustrating the upstream shared flow path 75 and the heating element 51 in the liquid ejector head 9.

[0106] In this embodiment, the upstream common flow path 75 includes a first common flow path 75A, a liquid inflow path 75B, and a liquid outflow path 75C.

[0107] The first common flow path 75A communicates with multiple pressure chambers 33 via an upstream separate flow path section 32, and extends from one end to the other end along the arrangement direction (X direction) of the multiple nozzles 41. The multiple pressure chambers 33 are each connected to the multiple nozzles 41 arranged along the arrangement direction (X direction). That is, the first common flow path 75A is a long, narrow flow path provided in the liquid nozzle head 9, extending from one end to the other along the arrangement direction (X direction) of the multiple nozzles 41. Similar to the above embodiment, the arrangement direction of the multiple nozzles 41 is sometimes simply referred to as the arrangement direction. As mentioned above, the arrangement direction is the X direction in the figure.

[0108] Liquid inflow path 75B is an inflow path that allows ink to flow in from the outside. In this embodiment, liquid inflow path 75B is connected to one end of the first common flow path 75A in this arrangement direction (X direction).

[0109] Liquid discharge path 75C is a discharge path for discharging ink to the outside. In this embodiment, liquid discharge path 75C is connected to the other end of the first common flow path 75A in this arrangement direction (X direction).

[0110] The heating element 51 is configured to heat the upstream common flow path 75 and extends along the arrangement direction (X direction) of the nozzles 41. That is, the heating element 51 is a strip-shaped element that extends along the long side direction (X direction) of the upstream common flow path 75.

[0111] In detail, one end of the heating element 51 along the liquid discharge path 75C in the long side direction (X direction) is at the same or approximately the same position in the X direction as one end of the first common flow path 75A along the liquid discharge path 75C in the long side direction (X direction). Therefore, one end of the heating element 51 along the liquid discharge path 75C in the long side direction (X direction) can heat one end of the first common flow path 75A along the long side direction (X direction).

[0112] Furthermore, one end of the heating element 51 along the liquid inflow path 75B in the long side direction (X direction) is at the same or approximately the same position in the X direction as one end of the first common flow path 75A along the liquid inflow path 75B in the long side direction (X direction). Therefore, one end of the heating element 51 along the liquid inflow path 75B in the long side direction (X direction) can heat one end of the first common flow path 75A along the liquid inflow path 75B in the long side direction (X direction).

[0113] Furthermore, the long side direction (X direction) of the heating element 51 extends in the same direction as the long side direction (X direction) of the first common flow path 75A and the arrangement direction (X direction) of the nozzles 41. Therefore, the heating element 51 is configured to continuously heat the ink flowing in the first common flow path 75A along the arrangement direction (X direction) of the nozzles 41, covering the entire area from one end to the other in the long side direction (X direction) of the first common flow path 75A.

[0114] The heating element 51 can be any component that can apply heat to the liquid in the upstream common flow path 75 by generating heat. For example, the heating element 51 is an electric heating wire that is heated by applying electricity.

[0115] In this embodiment, the heat generated on the liquid inflow path 75B side of the heating element 51 in the arrangement direction (X direction) of the nozzles 41 is greater than the heat generated on the liquid discharge path 75C side and the intermediate portion between the first common flow path 74A side and the liquid inflow path 74B side in the same arrangement direction (X direction). Furthermore, the heat generated on the liquid discharge path 75C side of the heating element 51 in the same arrangement direction (X direction) is greater than the heat generated in the intermediate portion.

[0116] That is, the heating element 51 includes a first region R1 on the side of the liquid inflow path 75B in the X direction, which is the arrangement direction of the nozzles 41 and the extension direction of the first common flow path 75A; a third region R3 on the side of the liquid discharge path 75C; and a second region R2 between the first region R1 and the third region R3. Among these first regions R1, second regions R2, and third regions R3, resistive components are arranged in series so that current flows in one direction in the order of first region R1, second region R2, and third region R3.

[0117] The heat generation of the first region R1, the second region R2 and the third region R3 of the heating element 51 is expressed by the following formula (3).

[0118] The calorific value of region 1 R1 > the calorific value of region 3 R3 > the calorific value of region 2 R2 ... Equation (3) Liquid supplied from the outside to the liquid inflow path 75B (referring to the Za direction) flows into one end of the arrangement direction (X direction) of the first common flow path 75A, which serves as the connection port between the liquid inflow path 75B and the first common flow path 75A. From this end, it flows along the arrangement direction (X direction) toward the liquid discharge path 75C provided at the other end (referring to the arrow Xa direction) and is discharged from the liquid discharge path 75C connected to the other end (referring to the arrow Zb direction).

[0119] In this embodiment, the heating element 51 is configured to heat the upstream common flow path 74 and extends along the extension direction of the first common flow path 75A, which is the arrangement direction (X direction) of the nozzles 41. Therefore, the ink flowing in the first common flow path 74A extending along the arrangement direction (X direction) of the nozzles 41 is heated by the heating element 50 extending along this arrangement direction (X direction). In addition, the amount of heat generated by the heating element 51 along this arrangement direction (X direction) satisfies the relationship of the above-described equation (3).

[0120] Therefore, in the liquid ejector head 9 of this embodiment, the ink temperature can be raised on the liquid inflow path 74B side of the upstream common flow path 75, and the temperature reduction of the ink that may occur due to flowing towards the liquid discharge path 75C in the first common flow path 75A can be raised in the third region R3 on the liquid discharge path 75C side. Therefore, it is possible to achieve uniformity of the temperature distribution in the arrangement direction (X direction) of the liquid flowing in the upstream common flow path 75 along the extension direction of the upstream common flow path 75, i.e., the arrangement direction (X direction). Furthermore, according to the structure of formula (3), by ensuring high heat generation in the first region R1, the ink that has just flowed in can be heated efficiently. Therefore, in the liquid ejector head 9 of this embodiment, it is not necessary to have a preheater that is conventionally provided to compensate for insufficient heat generation.

[0121] Therefore, the liquid ejector head 9 of this embodiment can suppress the high viscosity of ink and suppress the non-uniformity of temperature distribution in the arrangement direction (X direction) of the liquid flowing in the upstream common flow path 75, thereby improving the ink ejection characteristics of the plurality of nozzles 41 arranged along the arrangement direction.

[0122] Furthermore, the lengths of the first region R1, the second region R2, and the third region R3 in the heating element 51 in the arrangement direction (X direction) can be the same or different.

[0123] Furthermore, the boundary between the first region R1 and the second region R2 in the heating element 51 can also have different heat outputs, either in stages or continuously. Similarly, the boundary between the second region R2 and the third region R3 in the heating element 51 can also have different heat outputs, either in stages or continuously.

[0124] Furthermore, the heat generation of the first region R1, the second region R2, and the third region R3 of the heating element 51 only needs to satisfy the above formula (3), and the heat generation in the arrangement direction (X direction) of each region can be uniform or non-uniform. In this case, the average heat generation of each region or the minimum heat generation of each region only needs to satisfy the relationship of the above formula (3).

[0125] For example, the heat generation of region R1 can also be a structure in which the heat generation continuously or intermittently decreases from the end of the liquid inflow path 75B in the arrangement direction (X direction) toward the liquid discharge path 75C within the range of satisfying the relationship in equation (3) above. Similarly, the heat generation of region R2 can also be a structure in which the heat generation continuously or intermittently increases from the end of the liquid inflow path 75B in the arrangement direction (X direction) toward the liquid discharge path 75C within the range of satisfying the relationship in equation (3) above. Furthermore, the heat generation of region R3 can also be a structure in which the heat generation continuously or intermittently increases from the end of the liquid inflow path 75B in the arrangement direction (X direction) toward the liquid discharge path 75C within the range of satisfying the relationship in equation (3) above.

[0126] use Figure 5B To explain in more detail. Figure 5B This is a detailed diagram of an example of the heating element 51. For example, when the heating area of ​​the heating element 51 is divided into 15 regions and the heat output of each region is set in such a way as to ensure the uniformity of the temperature distribution of the liquid flowing in the common flow path 75 on the upstream side, the relationship of the above equation (3) must be satisfied.

[0127] Furthermore, in the liquid ejector head 6 of this embodiment, it is preferable that the flow rate of the ink flowing in the upstream common flow path 74 is a first flow rate below the reference flow rate per unit time.

[0128] The reference flow rate refers to the average flow rate of the ink flowing in the upstream common flow path 74 per unit time. The first flow rate is simply a flow rate lower than the reference flow rate, where the ink flowing into the liquid inflow path 75B is heated by the heating element 51 and flows towards the liquid discharge path 75C within the first common flow path 75A, and its temperature is maintained until it reaches the end of the liquid discharge path 75C within the first common flow path 75A. Therefore, the first flow rate can be appropriately set according to the shape and material of the upstream common flow path 75 and the heating element 51. Specifically, the first flow rate is approximately 1 mL / min to 10 mL / min, preferably 1 mL / min to 4 mL / min, but is not limited to these values.

[0129] The flow rate of the ink flowing in the upstream common flow path 74 can be controlled simply by adjusting the driving force of the pump that supplies ink to the liquid inflow path 74B and the pressure difference between the liquid inflow path 75B and the liquid discharge path 75C using a control unit (not shown). Furthermore, the flow rate of the ink flowing in the upstream common flow path 74 can also be adjusted by adjusting the cross-sectional area of ​​the section (YZ section) intersecting the long side direction (X direction) of the first common flow path 74A. Moreover, the flow rate of the ink flowing in the upstream common flow path 74 can be adjusted by two or more combinations thereof.

[0130] By setting the flow rate of the ink flowing in the upstream common flow path 74 to a first flow rate per unit time, the heat generated by the heating element 51 can be efficiently applied to the liquid flowing in the upstream common flow path 74. That is, since the ink flows at a low speed at the first flow rate, it is easy to be sufficiently heated immediately after flowing in. Therefore, there is no need to have a preheating heater, which is usually provided to compensate for insufficient heat generation. The liquid nozzle 9 of this embodiment can reduce the amount of heating of the upstream common flow path 74 by the heating element 51, suppress the high viscosity of the ink, and suppress the non-uniformity of temperature distribution in the arrangement direction (X direction) of the liquid flowing in the upstream common flow path 75. Therefore, the liquid nozzle 9 of this embodiment can improve the ink ejection characteristics of the plurality of nozzles 41 arranged along the arrangement direction. In addition, since the amount of heating of the heating element 51 can be reduced in the liquid nozzle 9 of this embodiment, the liquid nozzle 6 can also be miniaturized, simplified, and its manufacturing cost reduced.

[0131] As described above, the relationship of the above formula (3) of the heating element 51 can be achieved by adjusting the wiring pattern of the heating wire constituting the heating element 51, adjusting the cross-sectional area of ​​the section of the heating element 51 that is orthogonal to the arrangement direction (X direction), and combinations thereof.

[0132] The following description explains how the heating element 51 is adjusted to satisfy the relationship of the above formula (3) by adjusting the wiring pattern of the heating wire constituting the heating element 51.

[0133] Figure 6 This is an explanatory diagram of an example of the wiring pattern of the heating wire W of the heating element 51.

[0134] For example, the heating element 51 is a component in which a wiring pattern of heating wires W is disposed on a substrate S. The substrate S is made of an insulating material such as polyimide. For example, the heating element 51 is designed and adjusted in a way that makes the overall resistance value of the heating wires under applied voltage a specific value, such that the heat generated per unit area in the arrangement direction (X direction) of the nozzles 41 is a desired value.

[0135] For example, the heating element 51 is a component in which a wiring pattern of heating wires W is arranged on a substrate S. The substrate S is made of an insulating material such as polyimide. For example, the heating element 51 achieves the relationship of the above equation (3) through the wiring pattern of the heating wires W. That is, the heating element 51 has a wiring pattern in which the number of waveforms per unit area of ​​the heating wires W is adjusted so that the heat generated in the arrangement direction (X direction) of the nozzles 41 satisfies the relationship of the above equation (3).

[0136] Specifically, the first region R1 of the heating element 51 is a region where the wiring pattern of the heating wire W is formed in a wave shape with a first waveform density higher than the second waveform density. Waveform density is the number of waveforms per unit area. The third region R3 of the heating element 51 is a region where the wiring pattern of the heating wire W is formed in a wave shape with a second waveform density lower than the first waveform density. The second region R2 of the heating element 51 is a region of the metal wiring surface of the planar heating wire W extending along the arrangement direction (X direction).

[0137] The two-dimensional plane of the planar metal wiring surface of the heating wire W constituting the second region R2 is the two-dimensional plane of the outer wall surface of the upstream common flow path 75, which is elongated in the arrangement direction (X direction).

[0138] By making the second region R2 of the heating element 51 planar, the cross-sectional area of ​​the wiring is increased, thereby reducing heat generation. Furthermore, based on this effect, when the heating element 51 is installed into the housing 10, the presence of air bubbles and the like can be suppressed, and the second region R2 is positioned in close contact with the two-dimensional surface of the housing 10, covering its entire surface. Therefore, by making the second region R2 of the heating element 51 planar, the detachment of the heating element 51 from the housing 10 can be prevented.

[0139] In addition, Figure 6 As an example, the waveform representing the heating wire W in regions 1 R1 and 3 R3 is shown with the wave magnitude direction in the Z direction. However, the wave magnitude direction represented by the waveform representing the heating wire W in regions 1 R1 and 3 R3 can also be in the X direction. Furthermore, the wave magnitude directions represented by the waveform representing the heating wire W in regions 1 R1 and 3 R3 can be the same or different.

[0140] Since the waveform representing the heating wire W in the first region R1 and the third region R3 is not limited, the magnitude and direction of the wave can be adjusted according to the structure of the liquid ejector head 9, thereby increasing the freedom of removing the wiring that is electrically connected to the heating wire W.

[0141] In addition, as mentioned above, the heating element 51 can also be adjusted to satisfy the relationship of the above formula (3) by adjusting the cross-sectional area of ​​the section of the heating element 51 that is orthogonal to the arrangement direction (X direction).

[0142] In addition, as described above, the heating element 51 can be adjusted to satisfy the above formula (3) by a combination of adjusting the wiring pattern of the heating wire constituting the heating element 51 and adjusting the cross-sectional area of ​​the section of the heating element 51 that is orthogonal to the arrangement direction (X direction).

[0143] The extension portion that supplies power to the heating wire W of the heating element 51 is preferably provided at one end of the heating element 51 in the extension direction, i.e. the arrangement direction (X direction), and extends in a direction that intersects the arrangement direction (X direction).

[0144] Figure 7A and Figure 7B This is a schematic diagram of an example of the heating element 51. Figure 7B This is an example of an unfolded diagram of the heating element 51.

[0145] The heating element 51 includes a heating region R and an extension W2 extending in the extension direction (X direction) of the heating element 51. The heating region R is a region composed of the first region R1, the second region R2 and the third region R3 described above.

[0146] The extension W2 is connected to the end of the liquid discharge path 75C side (third region R3 side) in the arrangement direction (X direction) of the heating region R, and extends in a direction intersecting the arrangement direction (X direction). The extension W2 is connected to an electric power application device that applies electricity to the heating wire W. The extension W2 is the region that extends the end of the heating region R in this direction. That is, the extension W2 is made of the same material as the heating element 51, and is continuously and integrally formed with the heating element 51, and is set to have the same thickness as the heating element 51.

[0147] Thus, in the heating element 51, the extension W2 is connected not at both ends in the arrangement direction (X direction) in the heating region R, but at the end on the liquid discharge path 75C side, which is one end. Alternatively, the extension W2 may also be provided at the end of the heating element 51 in the heating region R on the liquid inflow path 75B side, which is one end in the arrangement direction (X direction).

[0148] Therefore, interference between the extension W2 and other components in the liquid ejector head 9, other than the extension W2, is suppressed, thus increasing the structural freedom of the liquid ejector head 9. Furthermore, the extension W2 is not connected to both ends of the heating region R, but only to one end of the heating region R on the liquid discharge path 75C side or the liquid inflow path 75B side. Therefore, compared to a structure with extensions at both ends, interference with other components can be suppressed. Furthermore, by… Figure 7A and Figure 7B The extension W2 shown is constructed to avoid interference with other components, ensuring a wider wiring width and thus reducing the wiring resistance (R = resistivity × length / (thickness × width)). This also suppresses heat generation in the extension W2 when current is applied (W = I). 2 R), which can effectively suppress the generation of abnormal heat. That is, through structural research, a highly reliable wiring design can be achieved.

[0149] The manufacturing method of the heating element 51 is not limited.

[0150] For example, the heating element 51 is constructed by bending a substrate on which heating wire W is provided.

[0151] Figure 8A This is a schematic diagram of an example of the heating element 51. Figure 8A In the example shown, substrate S is in its state before bending.

[0152] The substrate S is provided with heating wires W arranged in a manner that satisfies the relationship described in equation (3) above. The heating element 51 is constructed by bending the substrate S on which the heating wires W are provided along a pair of parallel bending lines B that are longer in the arrangement direction (X direction) so that the two ends of the bending lines face each other in the intersection direction that intersects the arrangement direction (X direction).

[0153] Figure 8B This is a perspective view of an example of a heating element 51 constructed by bending.

[0154] return Figure 8A Continuing the explanation, a portion of the heating wire W disposed on the substrate S is preferably configured to overlap with the bending region BR that bends along the bending line B of the substrate S.

[0155] Figure 8C yes Figure 8B The heating element 51 shown is in a cross-sectional view along line C-C'. Figure 8D yes Figure 8C An enlarged schematic diagram of the local area A shown.

[0156] like Figure 8C and Figure 8D As shown, a portion of the heating wire W disposed on the substrate S is preferably configured to overlap with the bending region BR of the substrate S. The bending region BR is the area in the substrate S that bends along the bending line B.

[0157] When manufacturing the liquid ejector head 9, as described above, the heating element 51 is housed within the housing portion 10 via an opening in the upper part (downstream side in the Z direction). More specifically, as... Figure 3 As shown, the heating element 51 is installed in the housing portion 10 by inserting and embedding the protrusion of the housing portion 10 into the inside of the bent heating element 51.

[0158] return Figure 8C and Figure 8D Continuing the explanation, when a portion of the heating wire W provided on the substrate S does not overlap with the bending region BR, the springback force of the bending region BR to return to its original planar state is low, sometimes making it difficult to insert the protrusion in the housing portion 10 into the inner side of the heating element 51. On the other hand, when a portion of the heating wire W provided on the substrate S overlaps with the bending region BR, this springback force comes into play, making it easy to insert the protrusion of the housing portion 10 into the inner side of the heating element 51. Furthermore, if this springback force is too strong, the heating element 51 may easily detach from the housing portion 10. Therefore, the amount of overlap between a portion of the heating wire W provided on the substrate S and the bending region BR of the substrate S is preferably adjusted to an amount that facilitates the aforementioned insertion and can suppress the peeling of the heating element 51 from the housing portion 10.

[0159] Alternatively, the overlap between the heating wire W and the bending area BR can be adjusted to be uneven in the arrangement direction (X direction) by setting the bending line B to a wavy line along the arrangement direction (X direction).

[0160] Figure 8E This is a schematic diagram showing an enlarged example of the bending area BR of the heating element 51.

[0161] like Figure 8E As shown, the pair of parallel bends B, which are longer along the arrangement direction (X direction) and are provided on the substrate S, can also be set as wavy lines extending along the arrangement direction (X direction). By setting the bends B as wavy lines, the aforementioned rebound force can be easily adjusted by adjusting the size of the waveform of the bends B.

[0162] In this way, by adopting a structure in which a portion of the heating wire W provided on the substrate S is arranged to overlap with the bending area BR that bends along the bending line B of the substrate S, it is possible to achieve improved manufacturing efficiency due to the increased ease of inserting the protrusion in the housing portion 10 into the inner side of the heating element 51, and improved quality due to the suppression of peeling of the heating element 51 achieved by adjusting the spring force.

[0163] Furthermore, in the liquid ejector head 9 of this embodiment, the cross-sectional area of ​​the heating element 51 along the arrangement direction (X direction) and the cross-sectional area of ​​the first common flow path 75A along the arrangement direction (X direction) can be further adjusted.

[0164] Figure 9A This is an explanatory diagram of an example of a heat-generating component 51 and a shared flow path 75 on the upstream side.

[0165] For example, the cross-sectional area of ​​the first common flow path 75A in the cross-sectional direction (YZ section) intersecting the arrangement direction (X direction) decreases from the liquid inflow path 75B side, which is one end of the arrangement direction (X direction), toward the liquid discharge path 75C side, which is the other end. In this case, the structure in which the cross-sectional area of ​​the heating element 51 in the cross-sectional direction (YZ section) intersecting the arrangement direction (X direction) increases from the liquid inflow path 75B side, which is one end of the arrangement direction (X direction), toward the liquid discharge path 75C side, which is the other end, is established.

[0166] Ink supplied from liquid inflow path 75B flows into the first common flow path 74A at the end of the liquid inflow path 74B in the X direction, i.e., the region with the largest cross-sectional area. Because the end of the liquid inflow path 74B in the X direction of the first common flow path 74A has the largest cross-sectional area, the ink flow velocity is lower compared to the smaller cross-sectional area of ​​the liquid outflow path 74C, allowing for efficient heating by the heating element 51. The flow velocity of the ink flowing in the first common flow path 74A is calculated as flow velocity [m / s] = flow rate [ml / min] / cross-sectional area [m² / min²]. 2 ]express.

[0167] Therefore, the cross-sectional area of ​​the first region R1 in the heating component 51 that heats the liquid inflow path 74B side of the first common flow path 74A can be smaller than the cross-sectional area of ​​the third region R3 on the liquid outflow path 74C side.

[0168] Figure 9B This is a schematic diagram of an example of a heat-generating component 51 and a shared flow path 75 on the upstream side.

[0169] For example, the cross-sectional area of ​​the first common flow path 75A in the cross-sectional direction (YZ section) intersecting the arrangement direction (X direction) increases from the liquid inflow path 75B side, which is one end of the arrangement direction (X direction), toward the liquid discharge path 75C side, which is the other end. In this case, the structure in which the cross-sectional area of ​​the heating element 51 in the cross-sectional direction (YZ section) intersecting the arrangement direction (X direction) decreases from the liquid inflow path 75B side, which is one end of the arrangement direction (X direction), toward the liquid discharge path 75C side, which is the other end, is established.

[0170] Ink supplied from liquid inflow path 75B flows into the end of the liquid inflow path 74B side in the first common flow path 74A in the X direction, i.e., the region with the smallest cross-sectional area. Since the end of the liquid inflow path 74B side in the X direction of the first common flow path 74A has the smallest cross-sectional area, the ink flow rate is higher compared to the liquid discharge path 74C side, which has a larger cross-sectional area. Therefore, in this case, it is necessary to heat the liquid inflow path 74B side in the X direction of the first common flow path 74A more efficiently than the liquid discharge path 74C side. Figure 9BIn the structure shown, the cross-sectional area of ​​the liquid inflow path 74B side in the arrangement direction (X direction) of the first common flow path 74A is smaller than the cross-sectional area of ​​the liquid outflow path 74C side. Therefore, there is a larger space on the outer side of the liquid inflow path 74B side of the first common flow path 74A compared to the liquid outflow path 74C side. Thus, it is possible to appropriately configure the heating element 51 such that the cross-sectional area of ​​the first region R1 heating the liquid inflow path 74B side of the first common flow path 74A is larger than the cross-sectional area of ​​the third region R3 on the liquid outflow path 74C side. Furthermore, by configuring this heating element 51, the liquid inflow path 74B side of the first common flow path 74A, which has a smaller cross-sectional area, can be heated efficiently.

[0171] In addition, with Figure 9B Compared to the structure, the preferred option is... Figure 9A The structure.

[0172] As explained above, the liquid nozzle 9 of this embodiment includes an upstream common flow path 75 (common flow path 72) and a heating element 51. The upstream common flow path 75 includes a first common flow path 75A, a liquid inflow path 75B, and a liquid discharge path 75C. The first common flow path 75A communicates with a plurality of pressure chambers 33 via an upstream individual flow path portion 32, and extends from one end to the other end along the arrangement direction (X direction) of the plurality of nozzles 41, wherein the plurality of pressure chambers 33 are respectively communicated with the plurality of nozzles 41 arranged along the arrangement direction (X direction). The liquid inflow path 75B communicates with one end of the first common flow path 75A along the arrangement direction (X direction). The liquid discharge path 75C communicates with the other end of the first common flow path 75A along the arrangement direction (X direction).

[0173] The heating element 51 is configured to heat the upstream common flow path 75 and extends along the arrangement direction (X direction) of the nozzles 41. The heat generation of the heating element 51 on the liquid inflow path 75B side in the arrangement direction (X direction) of the nozzles 41 is greater than the heat generation on the liquid outflow path 75C side in the same arrangement direction (X direction) and the intermediate portion between the first common flow path 74A side and the liquid inflow path 74B side. In addition, the heat generation of the heating element 51 on the liquid outflow path 75C side in the same arrangement direction (X direction) is greater than the heat generation of the intermediate portion. That is, the heating element 51 satisfies the relationship of the above equation (3).

[0174] Therefore, in the liquid ejector head 9 of this embodiment, the ink temperature is increased on the liquid inflow path 74B side of the upstream common flow path 75, and the temperature drop of the ink that may occur due to flowing towards the liquid discharge path 75C in the first common flow path 75A is increased in the third region R3 on the liquid discharge path 75C side. Therefore, the temperature drop of the liquid flowing in the first common flow path 75A can be suppressed, and the temperature distribution in the extension direction, i.e., the arrangement direction (X direction), of the first common flow path 75A can be made uniform.

[0175] Therefore, the liquid ejector head 9 of this embodiment can suppress the high viscosity of ink and suppress the non-uniformity of temperature distribution in the arrangement direction (X direction) of the liquid flowing in the first common flow path 75A, thereby improving the ink ejection characteristics of the plurality of nozzles 41 arranged along the arrangement direction.

[0176] Therefore, the liquid ejector head 9 of this embodiment can achieve improved ejection characteristics.

[0177] Furthermore, as described above, in this embodiment, the heating element 51 is provided as an example capable of heating the upstream common flow path 75, which is an example of a common flow path 72. However, the heating element 51 may also be configured to heat both the upstream common flow path 75 and the downstream common flow path 76, which are examples of a common flow path 72. In this case, the structure can be configured such that the heating element 51 is provided for the downstream common flow path 76 in the same way as the heating element 51 provided for the upstream common flow path 75.

[0178] Furthermore, in the liquid nozzle 9 of this embodiment, the upstream common flow path 74 described in the above embodiment may be used instead of the upstream common flow path 75. That is, the liquid nozzle 9 may also have a structure with an upstream common flow path 74 instead of the upstream common flow path 75. The upstream common flow path 74 is composed of a long strip-shaped first common flow path 74A extending along the arrangement direction (X direction) of the nozzles 41, a liquid inflow path 74B communicating with the central portion of the first common flow path 74A in the extension direction (X direction), and liquid discharge paths 74C (liquid discharge path 74C1, liquid discharge path 74C2) communicating with both ends of the first common flow path 74A in the extension direction (X direction).

[0179] In this case, the structures of the pair of first heating elements 50A and second heating elements 50B in the above embodiment can be set to be the same as those of the heating element 51 in this embodiment.

[0180] Furthermore, in the first and second embodiments described above, as an example, the following is shown: Figure 3As shown, heating element 50 and heating element 51 are respectively disposed on the downstream side (away from nozzle 41) in the +Z direction relative to the upstream common flow path 74. However, specifically, heating element 50 and heating element 51 are preferably disposed such that they cover the surfaces other than the surface of the upstream common flow path 74 on the nozzle 41 side.

[0181] Figure 10 This is a schematic diagram of an example of the ZY cross-section of liquid nozzles 6 and 9. Figure 10 The enlarged view indicates that the upstream side shares the flow path 74.

[0182] like Figure 10 As shown, the heating element 50 and the heating element 51 are preferably arranged to cover the outer walls of both ends in the Y direction of the upstream common flow path 74, and the surface of the upstream common flow path 74 opposite to the nozzle 41 (the outer wall of the downstream side in the +Z direction). Furthermore, it is preferable that... Figure 10 The structure shown is acceptable, but from the perspective of head miniaturization, it can also be used when there are manufacturing constraints. Figure 3 The configuration shown.

[0183] By arranging the heating element 50 and the heating element 51 such that they cover the surfaces other than the nozzle 41 side of the upstream common flow path 74, multi-face heating of the upstream common flow path 74 can be performed, and the heating efficiency of the ink flowing in the upstream common flow path 74 can be improved.

[0184] Furthermore, the embodiments described above are merely examples and are not intended to limit the scope of the invention. This new embodiment can be implemented in various other ways, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. This embodiment and its variations are included within the scope and spirit of the invention, and are also included within the scope of the invention as described in the claims and its equivalents.

[0185] In addition, this technology can also have the following configuration.

[0186] (1) A liquid ejector head, comprising: a common flow path having a first common flow path, a liquid inflow path and a liquid discharge path, the first common flow path being connected to a plurality of pressure chambers and extending along the arrangement direction from one end to the other end of a plurality of nozzles arranged along the arrangement direction, the plurality of pressure chambers being connected to the plurality of nozzles respectively, the liquid inflow path being connected to the central portion of the arrangement direction of the first common flow path, and the liquid discharge path being connected to both ends of the arrangement direction of the first common flow path respectively; and a heating element configured to heat the common flow path and extending along the arrangement direction.

[0187] (2) A liquid ejector head, comprising: a common flow path having a first common flow path, a liquid inflow path, and a liquid discharge path, the first common flow path communicating with a plurality of pressure chambers and extending along the arrangement direction from one end to the other end of a plurality of nozzles arranged along the arrangement direction, the plurality of pressure chambers respectively communicating with the plurality of nozzles, the liquid inflow path communicating with one end of the arrangement direction of the first common flow path, and the liquid discharge path communicating with the other end of the arrangement direction of the first common flow path; and a heating element configured to heat the common flow path and extending along the arrangement direction, wherein the heat generation of the heating element on the liquid inflow path side of the arrangement direction is greater than the heat generation of the liquid discharge path side of the arrangement direction and the heat generation of the intermediate portion between the liquid inflow path side and the liquid discharge path side, and the heat generation of the heating element on the liquid discharge path side of the arrangement direction is greater than the heat generation of the intermediate portion.

[0188] (3) The liquid nozzle according to (1) or (2), wherein the flow rate of the liquid flowing in the common flow path per unit time is a first flow rate below the reference flow rate.

[0189] (4) A liquid nozzle according to any one of (1) to (3), wherein the heating element comprises: a first region disposed on the liquid inflow path side in the arrangement direction, which is a region of a wiring pattern of an electric heating wire formed in a wave shape with a first waveform density higher than the second waveform density; a second region disposed in the middle portion between the liquid inflow path side and the liquid discharge path side in the arrangement direction, which is a region of a metal wiring surface of a planar electric heating wire extending in the arrangement direction; and a third region disposed on the liquid discharge path side in the arrangement direction, which is a region of a wiring pattern of an electric heating wire formed in a wave shape with the second waveform density.

[0190] (5) A liquid ejector head according to any one of (1) to (4), wherein the heating element comprises: a heating region extending in the arrangement direction; and an extension portion connected to an end of the heating region on the liquid discharge path side of the arrangement direction, extending in a direction intersecting the arrangement direction.

[0191] (6) A liquid nozzle according to any one of (1) to (5), wherein the heating element is constructed by bending a substrate on which heating wires are provided along a pair of parallel bends that are longer along the arrangement direction, such that the two ends of the substrate in the cross direction that intersects the arrangement direction face each other, and a portion of the heating wires is arranged to overlap with the bending area of ​​the substrate along the bends.

[0192] (7) A liquid nozzle according to any one of (1) to (6), wherein the cross-sectional area of ​​the first common flow path intersecting the arrangement direction decreases from one end of the arrangement direction toward the other end, and the cross-sectional area of ​​the heating element in the intersecting direction increases from one end of the arrangement direction toward the other end.

[0193] (8) A liquid nozzle according to any one of (1) to (7), wherein the heating element includes a first heating element and a second heating element extending along the arrangement direction, the first heating element and the second heating element being arranged such that they sandwich the liquid inflow path from mutually opposing directions from the arrangement direction.

[0194] (9) A liquid nozzle according to any one of (1) to (8), wherein the heat generation of the liquid inflow path side in the arrangement direction of the heating element is greater than the heat generation of the liquid discharge path side in the arrangement direction and the intermediate portion between the liquid inflow path side and the liquid discharge path side, and the heat generation of the liquid discharge path side in the arrangement direction is greater than the heat generation of the intermediate portion.

Claims

1. A liquid ejector head, wherein, have: A common flow path includes a first common flow path, a liquid inflow path, and a liquid outflow path. The first common flow path communicates with a plurality of pressure chambers and extends along the arrangement direction from one end to the other end of a plurality of nozzles arranged along the arrangement direction. The plurality of pressure chambers are respectively communicated with the plurality of nozzles. The liquid inflow path communicates with the central portion of the first common flow path along the arrangement direction, and the liquid outflow path communicates with both ends of the first common flow path along the arrangement direction. The heating element is configured to heat the common flow path and extends along the arrangement direction.

2. A liquid ejector head, wherein, have: A common flow path includes a first common flow path, a liquid inflow path, and a liquid outflow path. The first common flow path communicates with a plurality of pressure chambers and extends along the arrangement direction from one end to the other end of a plurality of nozzles arranged along the arrangement direction. The plurality of pressure chambers are respectively connected to the plurality of nozzles. The liquid inflow path is connected to one end of the first common flow path along the arrangement direction, and the liquid outflow path is connected to the other end of the first common flow path along the arrangement direction. The heating element is configured to heat the common flow path and extends along the arrangement direction. The heat generated on the liquid inflow path side of the arrangement direction of the heating element is greater than the heat generated on the liquid outflow path side and the intermediate portion between the liquid inflow path side and the liquid outflow path side in the arrangement direction. The heat generated on the liquid discharge path side of the arrangement direction of the heating element is greater than the heat generated in the middle part.

3. The liquid ejector head according to claim 1 or 2, wherein, The flow rate of the liquid flowing in the common flow path per unit time is the first flow rate below the reference flow rate.

4. The liquid ejector head according to claim 1 or 2, wherein, The heating element includes: The first region, located on the liquid inflow path side of the arrangement direction, is a region of wiring pattern of heating wires formed in a wave shape with a first waveform density that is higher than the second waveform density. The second region, located in the middle between the liquid inflow path side and the liquid outflow path side in the arrangement direction, is the region of the metal wiring surface of the planar heating wire extending in the arrangement direction; and The third region, located on the liquid discharge path side in the arrangement direction, is the area of ​​the wiring pattern of the heating wire formed into a wave shape with the second waveform density.

5. The liquid ejector head according to claim 1 or 2, wherein, The heating element includes: The heating area extends in the arrangement direction; and The extension is connected to the end of the liquid discharge path side in the arrangement direction of the heating area and extends in a direction intersecting the arrangement direction.

6. The liquid ejector head according to claim 1 or 2, wherein, The heating element is constructed by bending a substrate on which heating wires are provided along a pair of parallel bending lines that are longer along the arrangement direction, such that the two ends of the bending line intersect with the arrangement direction and face each other. A portion of the heating wire is configured to overlap with the bent area of ​​the substrate that bends along the bend line.

7. The liquid ejector head according to claim 1 or 2, wherein, The cross-sectional area of ​​the first common flow path intersecting the arrangement direction decreases from one end of the arrangement direction toward the other end. The cross-sectional area of ​​the heating element in the cross direction increases from one end of the arrangement direction toward the other end.

8. The liquid ejector head according to claim 1 or 2, wherein, The heating element includes a first heating element and a second heating element extending along the arrangement direction, respectively. The first heating element and the second heating element are arranged such that they sandwich the liquid inflow path from opposite directions in the arrangement direction.

9. The liquid ejector head according to claim 1 or 2, wherein, The heat generated on the liquid inflow path side of the arrangement direction of the heating element is greater than the heat generated on the liquid outflow path side and the intermediate portion between the liquid inflow path side and the liquid outflow path side in the arrangement direction. The heat generated on the liquid discharge path side of the arrangement direction of the heating element is greater than the heat generated in the middle part.

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