Liquid injection head and liquid injection device

Abstract

The system detects the near-end delamination of the coating on the liquid spray head. [Solution] The liquid spray head comprises a plurality of nozzles that spray liquid in the spraying direction, a spraying surface which is the surface facing the spraying direction, and a coating film provided on the spraying surface. The coating film has a first layer which has higher liquid repellency than the spraying surface, and a second layer which is a different color from the first layer. The second layer overlaps with at least a portion of the first layer when viewed in the opposite direction to the spraying direction.

Description

Technical Field

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

Background Art

[0002] Patent Document 1 discloses a liquid ejection head provided with a liquid repellent film such as a metal film containing a fluorine-based polymer on the ejection surface of a nozzle plate.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The liquid repellent film covering the ejection surface may gradually wear down or peel off due to contact with a wiping member or a suction member for maintaining the liquid ejection head. When the ejection surface is exposed due to peeling of the liquid repellent film or the like, there is a risk of problems occurring in the liquid ejection head. Therefore, it is required to be able to predict the life of the coating film such as the liquid repellent film before the ejection surface is exposed.

Means for Solving the Problems

[0005] In order to solve the above problems, a liquid ejection head according to a preferred aspect of the present disclosure is a liquid ejection head including a plurality of nozzles that eject liquid in an ejection direction, an ejection surface that is a surface facing the ejection direction, and a coating film provided on the ejection surface, where the coating film has a first layer having higher liquid repellency than the ejection surface and a second layer having a color different from that of the first layer, and the second layer overlaps at least a part of the first layer when viewed in the direction opposite to the ejection direction.

[0006] A liquid spraying device according to a preferred embodiment of the present disclosure comprises a liquid spraying head as described above and a detection unit for detecting whether or not the second layer is exposed. [Brief explanation of the drawing]

[0007] [Figure 1] This is a schematic diagram showing an example of the configuration of a liquid injection device according to the first embodiment. [Figure 2] This is an exploded perspective view of the liquid injection head according to the first embodiment. [Figure 3] This is a cross-sectional view of a part of the liquid injection head according to the first embodiment. [Figure 4] This is a bottom view of the liquid injection head according to the first embodiment. [Figure 5] This is an explanatory diagram illustrating an example of the configuration of the coating film in the first embodiment. [Figure 6] This is a schematic cross-sectional view of the coating film in the first embodiment. [Figure 7] This is an explanatory diagram showing the exposed state of the second layer of the coating film. [Figure 8] This is a schematic cross-sectional view of the coating film in the second embodiment. [Figure 9] This is an explanatory diagram showing the exposed state of the second layer of the coating film. [Figure 10] This is an explanatory diagram showing the exposed state of the third layer of the coating film. [Figure 11] This is a schematic cross-sectional view of the coating film in the third embodiment. [Figure 12] This is a schematic cross-sectional view of the coating film in the fourth embodiment. [Figure 13] This is a schematic cross-sectional view of the coating film in the fifth embodiment. [Figure 14] This is a schematic cross-sectional view of the coating film in the sixth embodiment. [Figure 15] Figure 14 is a plan view of the coating film shown, where the second layer is covered by the first layer. [Figure 16] Figure 14 is a plan view of the coating film in which the second layer is exposed from the first layer. [Figure 17] This is a schematic cross-sectional view of the coating film in the seventh embodiment. [Figure 18] It is a plan view of the state in which the second layer remains in the coating film shown in FIG. 17. [Figure 19] It is a plan view of the state in which the second layer has disappeared in the coating film shown in FIG. 17. [Figure 20] It is a schematic diagram showing a configuration example of a liquid ejection device according to the eighth embodiment. [Figure 21] It is a bottom view of a liquid ejection head according to the eighth embodiment.

Embodiments for Carrying Out the Invention

[0008] Hereinafter, preferred embodiments according to the present disclosure will be described with reference to the accompanying drawings. Note that the dimensions and scales of each part in the drawings are appropriately different from the actual ones, and there are also parts schematically shown for easy understanding. Further, the scope of the present disclosure is not limited to these embodiments unless there is a description to specifically limit the present disclosure in the following description.

[0009] For the sake of convenience, the following description will be made using the X-axis, Y-axis, and Z-axis that intersect each other as appropriate. Further, in the following, one direction along the X-axis is the X1 direction, and the direction opposite to the X1 direction is the X2 direction. Similarly, the directions opposite to each other along the Y-axis are the Y1 direction and the Y2 direction. Also, the directions opposite to each other along the Z-axis are the Z1 direction and the Z2 direction. The Z2 direction is the ejection direction DJ described later.

[0010] Typically, the Z-axis is a vertical axis, and the Z2 direction corresponds to the downward direction in the vertical direction. However, the Z-axis does not have to be a vertical axis. Also, the X-axis, Y-axis, and Z-axis typically intersect at right angles to each other, but are not limited thereto, and for example, they may intersect at an angle within the range of 80° or more and 100° or less.

[0011] 1. First Embodiment 1-1. Schematic Configuration of Liquid Ejection Device Figure 1 is a schematic diagram showing an example configuration of a liquid injection device 100 according to the first embodiment. The liquid injection device 100 is an inkjet printing device that sprays ink, which is an example of a "liquid," as droplets onto a medium M. The medium M is typically printing paper. However, the medium M is not limited to printing paper and may be any material to be printed on, such as a resin film or a cloth.

[0012] As shown in Figure 1, the liquid injection device 100 comprises a liquid container 10, a control unit 20, a transport mechanism 30, a moving mechanism 40, a liquid injection head 50, a notification unit 60, a wiping member 71, a cap member 72, and a sensor 73. These will be briefly described below in order based on Figure 1.

[0013] The liquid container 10 stores ink. Specific examples of the liquid container 10 include a cartridge detachable from the liquid spray device 100, a bag-shaped ink pack made of a flexible film, and an ink tank from which ink can be refilled. The type of ink stored in the liquid container 10 is not particularly limited and is arbitrary.

[0014] The control unit 20 includes, for example, a processing circuit such as a CPU (Central Processing Unit) or FPGA (Field Programmable Gate Array) and a storage circuit such as a semiconductor memory, and controls the operation of each element of the liquid injection device 100.

[0015] The transport mechanism 30, under the control of the control unit 20, transports the medium M in the transport direction DM, which is the Y1 direction. The moving mechanism 40, under the control of the control unit 20, reciprocates the liquid injection head 50 in the X1 direction and the X2 direction. In the example shown in Figure 1, the moving mechanism 40 has a roughly box-shaped transport body 41 called a carriage that houses the liquid injection head 50, and a transport belt 42 to which the transport body 41 is fixed. In addition to the liquid injection head 50, the aforementioned liquid container 10 may also be mounted on the transport body 41.

[0016] In this embodiment, the moving mechanism 40 not only reciprocates the liquid spray head 50 along the X-axis over the entire width of the medium M, but is also movable to a position that overlaps with the wiping member 71, the cap member 72, or the sensor 73 when viewed along the Z-axis.

[0017] Under the control of the control unit 20, the liquid spray head 50 sprays ink supplied from the liquid container 10 onto the medium M from each of its multiple nozzles in the spray direction DJ. This spraying occurs in parallel with the transport of the medium M by the transport mechanism 30 and the reciprocating movement of the liquid spray head 50 by the moving mechanism 40, thereby forming an image of ink on the surface of the medium M. As will be described in detail later, the liquid spray head 50 has multiple head tips 54.

[0018] The notification unit 60 is a device that notifies various types of information under the control of the control unit 20. Specifically, the notification unit 60 is a display device that includes various display panels, such as a liquid crystal display panel or an organic EL (electro-luminescence) display panel. In this embodiment, the notification unit 60 notifies information such as the replacement time or maintenance time for the liquid injection head 50.

[0019] The notification unit 60 is not limited to a configuration that provides notification via a display device, but may also be configured to provide notification by lighting or flashing a light-emitting element such as an LED (light-emitting diode), or by providing notification via sound, etc.

[0020] The wiping member 71 is a member for wiping the spray surface F of the liquid spray head 50, which will be described later. In the example shown in Figure 1, the wiping member 71 is made of an elastic material such as rubber, has a long shape extending in the direction along the X axis, and is an elastic member such as a blade-shaped rubber member that protrudes in the Z1 direction, and moves back and forth in the direction along the Y axis by being driven by a moving mechanism such as an actuator (not shown). The wiping member 71 is also positioned off-center in the direction along the X axis from the transport area of ​​the medium M. When the wiping member 71 wipes the spray surface F, the moving mechanism 40 positions the liquid spray head 50 at a position that overlaps with the movement range of the wiping member 71 when viewed in the direction along the Z axis. This makes it possible to wipe the spray surface F with the wiping member 71.

[0021] Here, the length of the wiping member 71 in the direction along the X-axis is approximately equal to, or slightly longer than, the width in the direction along the X-axis of a group of two adjacent head tips 54 in the direction along the X-axis. Note that the wiping member 71 is not limited to the example shown in Figure 1, and may be composed of, for example, two or more blade-shaped elastic members, or of a fibrous material such as a woven or nonwoven fabric, or a porous material such as a sponge. Furthermore, the wiping member 71 may be provided or omitted as needed.

[0022] The cap member 72 is a lid having recesses that cap all the nozzles N of the liquid spray head 50. Specifically, although not shown, the cap member 72 comprises, for example, a main body with a recess shape made of resin or the like, and an annular edge portion made of an elastic material such as rubber or elastomer, provided at the tip of the main body in the Z1 direction. The cap member 72 reciprocates in the direction along the Z axis by a moving mechanism such as an actuator (not shown). The cap member 72 then contacts the spray surface F, described later, with its edge portion, forming a closed space between it and the spray surface F. This prevents the ink in the nozzles N from evaporating and becoming thicker. The cap member 72 is also positioned off-center from the transport area of ​​the medium M in the direction along the X axis. When capping with the cap member 72 is performed, the moving mechanism 40 positions the liquid spray head 50 so that it overlaps with the cap member 72 when viewed in the direction along the Z axis. This enables capping of the spray surface F by the cap member 72.

[0023] Furthermore, a suction port connected to a vacuum pump or other pressure reducing mechanism may be provided on the bottom surface of the recess of the cap member 72. In this case, the nozzle N can be cleaned by suction using the negative pressure from the pressure reducing mechanism. Thus, the cap member 72 may be used as a suction member for sucking the nozzle N. Also, the cap member 72 may be provided or omitted as needed.

[0024] Sensor 73 is a sensor that detects changes in the color of the coating film 80, which will be described later. Specifically, sensor 73 is an optical sensor that detects, for example, the intensity of light reflected by the coating film 80, which will be described later. The control unit 20 has the function of a determination unit 21 that determines whether or not the second layer 81b, which will be described later, is exposed, based on the detection result of sensor 73. If the determination unit 21 determines that the second layer 81b is exposed, the control unit 20 causes the notification unit 60 to notify that the second layer 81b is exposed, that the lifespan of the coating film 80 is nearing its end, or that it is time to replace the liquid spray head 50.

[0025] Here, the sensor 73 and the determination unit 21 constitute a detection unit 74 that detects whether or not the second layer 81b is exposed. This allows the detection unit 74 to confirm whether or not the second layer 81b is exposed. Therefore, the effort required for visual inspection is eliminated. In addition, compared to visual inspection, the detection capability or resolution of the color difference is higher, resulting in higher detection accuracy. As a result, the degree of freedom in the colors of the first layer 81a and the second layer 81b can be increased, and the size of the marks or characters can be reduced.

[0026] In this embodiment, the sensor 73 consists of two sensors arranged along the Y-axis, corresponding to the arrangement of the second layer 81b described later.

[0027] 1-2. Liquid spray head Figure 2 is an exploded perspective view of the liquid injection head 50 according to the first embodiment. As shown in Figure 2, the liquid injection head 50 comprises a flow channel structure 51, a substrate unit 52, a holder 53, two head tips 54-1 and 54-2, and a fixing plate 55. Head tips 54-1 and 54-2 are the same as the head tip 54 shown in Figure 1. Hereafter, when head tips 54-1 and 54-2 are not distinguished, they will each be referred to as head tip 54.

[0028] The flow channel structure 51, substrate unit 52, holder 53, head chips 54-1 and 54-2, and fixing plate 55 are arranged in that order, stacked in the Z2 direction. These are joined to each other as appropriate by screws or adhesive. The parts of the liquid injection head 50 will be described sequentially below.

[0029] The flow channel structure 51 is a structure that has one or more flow channels inside for supplying ink stored in the aforementioned liquid container 10 to two head chips 54. The flow channel structure 51 is composed of a laminate formed by stacking multiple substrates in a direction along the Z axis, although not shown in the figure. Each of the multiple substrates is appropriately provided with grooves and holes for the flow channels, a filter chamber having a filter for capturing foreign matter contained in the ink, etc. The multiple substrates are joined to each other by means of adhesive, brazing, welding, or screw fastening, for example. A sheet-like sealing member made of rubber material or the like may be appropriately placed between the multiple substrates as needed. The number or thickness of the substrates constituting the flow channel structure 51 is determined according to the shape of the supply flow channels, etc., and is not particularly limited and is arbitrary. Each of the multiple substrates is not particularly limited and is made of, for example, metal, ceramics, or a resin composition.

[0030] Although not shown in the diagram, the flow channel structure 51 is provided with two supply channels for supplying ink to the head chip 54. Each of the two supply channels has one inlet for receiving ink and one outlet for discharging ink. Each inlet of each supply channel is provided on the surface of the flow channel structure 51 facing in the Z1 direction. Conversely, each outlet of each supply channel is provided on the surface of the flow channel structure 51 facing in the Z2 direction.

[0031] Multiple connecting pipes 51a are provided on the surface of the flow channel structure 51 facing the Z1 direction. Each of the multiple connecting pipes 51a is a tubular body that protrudes from the surface of the flow channel structure 51 facing the Z1 direction. In the example shown in Figure 2, two connecting pipes 51a corresponding to the two supply channels mentioned above are provided on the flow channel structure 51, and each connecting pipe 51a is connected to the inlet of the corresponding supply channel. Separate ink tubes are connected to the two connecting pipes 51a to receive the supply of different types of ink, and these ink tubes are connected to the aforementioned liquid container 10.

[0032] Furthermore, the channel structure 51 is provided with multiple wiring holes 51b for passing the wiring 52c of the substrate unit 52, which will be described later. The channel structure 51 is also provided with holes (not shown), and is fixed to the holder 53 by screw fastening through these holes.

[0033] The substrate unit 52 is an assembly having mounting components for electrically connecting the liquid injection head 50 to the control unit 20. The substrate unit 52 includes a circuit board 52a, a connector 52b, and wiring 52c.

[0034] The circuit board 52a is a printed circuit board such as a rigid wiring board having wiring for electrically connecting each head chip 54 to the connector 52b. The circuit board 52a is positioned between the flow channel structure 51 and the holder 53, and the connector 52b is installed on the surface of the circuit board 52a facing the Z1 direction. The circuit board 52a is provided with a plurality of wiring holes 52d through which the wiring board 54i of the head chip 54 passes. As a result, the wiring board 54i is connected to the surface of the circuit board 52a facing the Z1 direction through the wiring holes 52d.

[0035] Connector 52b is a connecting component that is electrically connected to circuit board 52a. Wiring 52c is connected to connector 52b. Wiring 52c is a flexible wiring board such as COF (Chip On Film), FPC (Flexible Printed Circuit), or FFC (Flexible Flat Cable) for electrically connecting connector 52b and control unit 20. Circuit board 52a is fixed to the flow path structure 51 or holder 53 by screws or the like.

[0036] The holder 53 is a structure that houses and supports multiple head chips 54. The holder 53 is made of, for example, a metal, ceramic, or resin composition. The holder 53 is provided with a recess 53a and multiple wiring holes 53b. The recess 53a opens toward the Z2 direction and is a space in which multiple head chips 54 are arranged. Each of the multiple wiring holes 53b is a hole through which the wiring board 54i of the head chip 54 passes toward the board unit 52. The recess 53a may be composed of multiple recesses, each divided for each head chip 54.

[0037] Although not shown in the diagram, the holder 53 includes one or more channels for supplying two head chips 54 and also functions as a channel structure. Therefore, the supply channels of the channel structure 51 are connected to the head chips 54 via the channels of the holder 53. Such a holder 53 may be composed of a laminate of multiple substrates stacked in the direction along the Z-axis, similar to the channel structure 51. Note that the channels of the holder 53 may be provided as needed or omitted. In this case, the supply channels of the channel structure 51 are connected to the head chips 54 without going through the channels of the holder 53.

[0038] Each head chip 54 ejects ink. Each head chip 54 is provided with a wiring board 54i. Note that Figure 2 shows a simplified representation of the configuration of each head chip 54. Details of the head chip 54 will be explained later based on Figure 3.

[0039] The fixing plate 55 is a plate-shaped member to which two head tips 54 and a holder 53 are fixed, and has openings 55a-1 and 55a-2 and a surface FF. Opening 55a-1 exposes multiple nozzles N of head tip 54-1 to the outside. Opening 55a-2 exposes multiple nozzles N of head tip 54-2 to the outside. Surface FF is part of the spray surface F described later. The fixing plate 55 is positioned with the two head tips 54 sandwiched between it and the holder 53, and each head tip 54 and holder 53 are fixed with adhesive or the like. In this way, the head tips 54-1 and 54-2 are fixed to the fixing plate 55. In the following, openings 55a-1 and 55a-2 may be referred to as opening 55a without distinction.

[0040] The fixing plate 55 is made of a metal material such as stainless steel, titanium, and magnesium alloy.

[0041] Figure 3 is a cross-sectional view of a part of the liquid spray head 50 according to the first embodiment. As shown in Figure 3, the head tip 54 is provided with a plurality of nozzles N for spraying ink. The plurality of nozzles N are divided into nozzle row La and nozzle row Lb. Nozzle row La and nozzle row Lb are sets of a plurality of nozzles N arranged along the Y axis. Nozzle row La and nozzle row Lb are spaced apart from each other in the direction of the X axis.

[0042] The head tip 54 has a liquid storage chamber Ra, a plurality of pressure chambers Ca, and a plurality of drive elements Ea as components corresponding to the nozzle row La. The liquid storage chamber Ra is a common liquid chamber that is continuous across a plurality of nozzles N of the nozzle row La. Ink is introduced into the liquid storage chamber Ra through an inlet Ra_in. Each of the pressure chambers Ca and drive elements Ea is provided for each nozzle N of the nozzle row La. The pressure chamber Ca is a space that communicates with the nozzle N. Each of the plurality of pressure chambers Ca is filled with ink supplied from the liquid storage chamber Ra. The drive elements Ea vary the pressure of the ink in the pressure chamber Ca. The drive elements Ea are, for example, piezoelectric elements that change the volume of the pressure chamber Ca by deforming the wall surface of the pressure chamber Ca, or heating elements that generate bubbles in the pressure chamber Ca by heating the ink in the pressure chamber Ca. By varying the pressure of the ink in the pressure chamber Ca, the drive elements Ea cause the ink in the pressure chamber Ca to be ejected from the nozzle N.

[0043] Furthermore, the head tip 54 has a liquid storage chamber Rb, a plurality of pressure chambers Cb, and a plurality of drive elements Eb as components corresponding to the nozzle row Lb. The liquid storage chamber Rb is a common liquid chamber that is continuous across a plurality of nozzles N of the nozzle row Lb. Ink is introduced into the liquid storage chamber Rb through an inlet Rb_in. Each of the pressure chambers Cb and drive element Eb is provided for each nozzle N of the nozzle row Lb. Each of the plurality of pressure chambers Cb is filled with ink supplied from the liquid storage chamber Rb. The drive element Eb is, for example, the piezoelectric element or heating element described above. The drive element Eb changes the pressure of the ink in the pressure chamber Cb, causing the ink in the pressure chamber Cb to be ejected from the nozzle N.

[0044] As shown in Figure 3, the head chip 54 includes a communication plate 18a, a pressure chamber substrate 18b, a nozzle plate 18c, a compliance substrate 18d, a diaphragm 18e, a plurality of drive elements Ea, Eb, a cover 18g, and a case 18h.

[0045] The communication plate 18a and the pressure chamber substrate 18b are stacked in this order in the Z1 direction, forming a flow path for supplying ink to multiple nozzles N. The region located in the Z1 direction from the stack consisting of the communication plate 18a and the pressure chamber substrate 18b is where the diaphragm 18e, multiple drive elements Ea and Eb, cover 18g, case 18h, wiring board 18i, and drive circuit 18j are installed. On the other hand, the region located in the Z2 direction from the said stack is where the nozzle plate 18c and compliance substrate 18d are installed. Each element of the head chip 54 is generally a plate-shaped member that is elongated in the Y direction, and is joined to each other by means of adhesive or direct bonding, for example.

[0046] The nozzle plate 18c is a plate-shaped member laminated on the communication plate 18a, having multiple nozzles N in nozzle rows La and nozzle rows Lb, respectively. Each of the multiple nozzles N is a through-hole through which ink passes, and the ink is ejected in the Z2 direction, which is the ejection direction DJ. Here, the nozzle plate 18c has its thickness direction along the Z axis. The surface of the nozzle plate 18c facing the Z2 direction constitutes the nozzle surface FN. The nozzle plate 18c is manufactured by processing a silicon single crystal substrate using semiconductor manufacturing technology, for example, processing techniques such as dry etching or wet etching. However, other known methods and materials may be used in the manufacture of the nozzle plate 18c as appropriate. Also, the cross-sectional shape of the nozzle is typically circular, but is not limited to this, and may be non-circular, for example, polygonal or elliptical. Here, the nozzle plate 18c is joined to the surface of the communication plate 18a facing the Z2 direction with an adhesive or the like. In this way, the liquid injection head 50 is equipped with a nozzle plate 18c having multiple nozzles N.

[0047] The communication plate 18a is provided with spaces R1a and R1b, multiple supply channels RRa and RRb, and multiple communication channels NRa and NRb, respectively, as flow paths communicating with the nozzles N for each of the nozzle rows La and Lb. Spaces R1a and R1b are elongated openings extending in the direction along the Y-axis when viewed in a plan view along the Z-axis. Each of the supply channels RRa and RRb and the communication channels NRa and NRb are through holes formed for each nozzle N. Each supply channel RRa communicates with space R1a. Each supply channel RRb communicates with space R1b.

[0048] On the surface of the communication plate 18a facing the Z2 direction, the nozzle plate 18c and the compliance substrate 18d are laminated, and the aforementioned spaces R1a, R1b and communication channels NRa, NRb are opened.

[0049] The pressure chamber substrate 18b is a plate-shaped member provided with a plurality of pressure chambers Ca and a plurality of pressure chambers Cb. The plurality of pressure chambers Ca are arranged in the direction along the Y axis. Similarly, the plurality of pressure chambers Cb are arranged in the direction along the Y axis. Each pressure chamber Ca is formed for each nozzle N of the nozzle row La and is an elongated space extending in the direction along the X axis in a plan view. Similarly, each pressure chamber Cb is formed for each nozzle N of the nozzle row Lb and is an elongated space extending in the direction along the X axis in a plan view. The communication plate 18a and the pressure chamber substrate 18b are manufactured, for example, by processing a silicon single crystal substrate using semiconductor manufacturing technology, similar to the nozzle plate 18c described above. However, other known methods and materials may be used as appropriate for the manufacture of the communication plate 18a and the pressure chamber substrate 18b, respectively.

[0050] Pressure chamber Ca communicates with both the communication channel NRa and the supply channel RRa. Therefore, pressure chamber Ca communicates with the nozzle N of the nozzle row La via the communication channel NRa, and with space R1a via the supply channel RRa. Similarly, pressure chamber Cb communicates with both the communication channel NRb and the supply channel RRb. Therefore, pressure chamber Cb communicates with the nozzle N of the nozzle row Lb via the communication channel NRb, and with space R1b via the supply channel RRb.

[0051] A diaphragm 18e is positioned on the surface of the pressure chamber substrate 18b facing the Z1 direction. The diaphragm 18e is an elastically vibrating plate-shaped member. The diaphragm 18e has, for example, a first layer and a second layer, which are stacked in this order in the Z1 direction. The first layer is, for example, an elastic film composed of silicon oxide (SiO2). This elastic film is formed, for example, by thermal oxidation of one surface of a silicon single crystal substrate. The second layer is, for example, an insulating film composed of zirconium oxide (ZrO2). This insulating film is formed, for example, by forming a zirconium layer by sputtering and then thermally oxidizing the layer. Note that the diaphragm 18e is not limited to the stacked configuration of the first and second layers described above, and may be composed of, for example, a single layer or three or more layers.

[0052] Multiple drive elements Ea and Eb are arranged on the surface of the diaphragm 18e facing the Z1 direction. Each of the drive elements Ea and Eb is a passive element that deforms in response to the supply of a drive signal. Each of the drive elements Ea and Eb is elongated in shape, extending in the direction along the X axis in a plan view. Multiple drive elements Ea are arranged in the direction along the Y axis to correspond to multiple pressure chambers Ca. In a plan view, the drive elements Ea overlap with the pressure chambers Ca. Similarly, multiple drive elements Eb are arranged in the direction along the Y axis to correspond to multiple pressure chambers Cb. In a plan view, the drive elements Eb overlap with the pressure chambers Cb.

[0053] Each of the driving elements Ea and Eb, although not shown in the diagram, has a first electrode, a piezoelectric layer, and a second electrode, and these are stacked in this order in the Z1 direction. One of the first and second electrodes is an individual electrode that is spaced apart from each other for each driving element Ea or driving element Eb, and a driving signal is applied to this electrode. The other electrode is a strip-shaped common electrode that extends along the Y axis so as to be continuous across multiple driving elements Ea or multiple driving elements Eb, and a predetermined reference potential is supplied to this electrode. Examples of metallic materials for these electrodes include platinum (Pt), aluminum (Al), nickel (Ni), gold (Au), and copper (Cu), and one of these can be used alone or two or more can be used in combination in the form of an alloy or stacking. The piezoelectric layer is made of a piezoelectric material such as lead zirconate titanate (Pb(Zr,Ti)O3) and, for example, is a strip-shaped layer extending along the Y-axis so as to be continuous across multiple drive elements Ea or multiple drive elements Eb. However, the piezoelectric layer may be provided individually for each drive element Ea or each drive element Eb. When the diaphragm 18e vibrates in conjunction with the deformation of the drive element Ea, the pressure in the pressure chamber Ca fluctuates, causing ink to be ejected from the nozzle N of the nozzle row La. Similarly, when the diaphragm 18e vibrates in conjunction with the deformation of the drive element Eb, the pressure in the pressure chamber Cb fluctuates, causing ink to be ejected from the nozzle N of the nozzle row Lb. In addition, instead of the drive elements Ea and Eb, heating elements that heat the ink in the pressure chambers Ca and Cb may be used as drive elements.

[0054] The cover 18g is a plate-shaped member installed on the surface of the diaphragm 18e facing the Z1 direction, protecting the multiple drive elements Ea and Eb, and reinforcing the mechanical strength of the diaphragm 18e. Here, the multiple drive elements Ea and Eb are housed between the cover 18g and the diaphragm 18e. The cover 18g is made of, for example, a resin material.

[0055] Case 18h is a case for storing ink supplied to multiple pressure chambers Ca and multiple pressure chambers Cb. Case 18h is made of, for example, a resin material. Case 18h is provided with spaces R2a, R2b and inlets Ra_in, Rb_in. Space R2a is a space that communicates with the aforementioned space R1a and, together with space R1a, functions as a liquid storage chamber Ra, which is a reservoir for storing ink supplied to the multiple pressure chambers Ca. The ink in liquid storage chamber Ra is supplied to pressure chamber Ca via each supply channel RRa. Similarly, space R2b is a space that communicates with the aforementioned space R1b and, together with space R1b, functions as a liquid storage chamber Rb, which is a reservoir for storing ink supplied to the multiple pressure chambers Cb. The ink in liquid storage chamber Rb is supplied to pressure chamber Cb via each supply channel RRb.

[0056] The compliance substrate 18d is a substrate that absorbs pressure fluctuations of the ink in the liquid storage chambers Ra and Rb. The compliance substrate 18d is laminated on the communication plate 18a at a different position from the nozzle plate 18c. That is, the compliance substrate 18d and the nozzle plate 18c are laminated on the surface of the communication plate 18a facing the Z2 direction so that they do not overlap each other.

[0057] The compliance substrate 18d comprises a compliance film 18d1 and a frame 18d2. The compliance film 18d1 is a flexible resin film that constitutes the walls of the liquid storage chambers Ra and Rb. The surface of the compliance film 18d1 facing the Z1 direction is joined to the communication plate 18a with an adhesive such as an epoxy adhesive. On the other hand, the frame 18d2 is joined to the surface of the compliance film 18d1 facing the Z2 direction with an adhesive such as a urethane adhesive or an epoxy adhesive. The frame 18d2 is a frame-shaped member for forming the compliance spaces Rca and Rcb. The frame 18d2 is made of a metallic material such as stainless steel, aluminum, titanium, and magnesium alloy. The compliance substrate 18d may also be a flexible thin plate made of metal.

[0058] The surface of the frame 18d2 facing the Z2 direction is joined to the aforementioned fixing plate 55 with an adhesive such as an epoxy adhesive. Here, compliance spaces Rca and Rcb are formed between the compliance film 18d1 and the fixing plate 55, partitioned by the frame 18d2. Compliance space Rca is separated from the liquid storage chamber Ra via the compliance film 18d1 and is a space that allows deformation of the compliance film 18d1 in response to pressure changes of the ink in the liquid storage chamber Ra. Compliance space Rcb is separated from the liquid storage chamber Rb via the compliance film 18d1 and is a space that allows deformation of the compliance film 18d1 in response to pressure changes of the ink in the liquid storage chamber Rb.

[0059] Here, the surface FF of the fixed plate 55 facing the Z2 direction and the aforementioned nozzle surface FN constitute the injection surface F facing the injection direction DJ. In this way, the nozzle plate 18c includes at least a portion of the injection surface F.

[0060] The spray surface F is the surface of the nozzle plate 18c facing the spray direction DJ when there is no fixing plate 55, and when there is a fixing plate 55 as in this embodiment, it is the surface composed of the nozzle surface FN, which is the surface of the nozzle plate 18c facing the spray direction DJ, and the surface FF of the fixing plate 55 facing the spray direction DJ. Such a spray surface F is wiped by the wiping member 71 or comes into contact with the cap member 72 for sucking the nozzle. In addition, the coating film 81 and the coating film 82 may be a single continuous film.

[0061] A coating film 80 is provided on the spray surface F. The coating film 80 is divided into a coating film 81 provided on the nozzle surface FN and a coating film 82 provided on surface FF. Thus, the liquid spray head 50 comprises the spray surface F and the coating film 80. Details of the coating film 80 will be described later with reference to Figures 4 to 8.

[0062] Furthermore, a sealant B, consisting of an epoxy adhesive or a silicone adhesive, is filled into the gap between the inner surface of the opening 55a of the fixing plate 55 and the outer surface of the nozzle plate 18c.

[0063] Furthermore, although not shown in Figure 3, the aforementioned wiring board 54i for electrically connecting the control unit 20 and the head chip 54 is mounted on the surface of the diaphragm 18e facing the Z1 direction. The wiring board 54i is, for example, a COF (Chip On Film), FPC (Flexible Printed Circuit), or FFC (Flexible Flat Cable) substrate, and a drive circuit 54j for supplying drive voltage to each drive element Ea and Eb is mounted on the wiring board 54i. The drive circuit 54j is a circuit that switches whether or not to supply at least a part of the waveform included in the drive signal D as a drive pulse based on the control signal S.

[0064] 1-3.Coating film Figure 4 is a bottom view of the liquid injection head 50 according to the first embodiment. Figure 5 is a cross-sectional view of the coating film 81 in the first embodiment. Figure 6 is a schematic cross-sectional view of the coating film 81 in the first embodiment. As shown in Figure 5, a protective layer 91 and a plasma polymerization layer 92 are provided between the surface of the nozzle plate 18c and the coating film 81. Furthermore, the first layer 81a is provided over the entire surface of the nozzle plate 18c. That is, the first layer 81a is provided over the entire surface of the nozzle plate 18c other than the nozzle surface FN (including the inner circumferential surface of the nozzle N), not just the nozzle surface FN of the nozzle plate 18c.

[0065] The protective layer 91 is provided on the surface of the nozzle plate 18c and is a layer for protecting the nozzle plate 18c from ink, and is composed of, for example, tantalum oxide. The protective layer 91 is formed, for example, by atomic layer deposition. The constituent material of the protective layer 91 is not limited to tantalum oxide, and may be an oxide or nitride of at least one element from among tantalum, titanium, zirconium, niobium, vanadium, hafnium, silicon, aluminum, tungsten, and yttrium. The protective layer 91 may be provided as needed or omitted.

[0066] The plasma polymerization layer 92 is provided on the protective layer 91 and is a layer that enhances the adhesion between the coating film 81 and the nozzle plate 18c. For example, it is formed by plasma polymerization of a silicon material. In such a plasma polymerization layer 92, when the coating film 81 is formed using a silane coupling agent, the adhesion between the coating film 81 and the nozzle plate 18c can be enhanced. The plasma polymerization layer 92 may be provided as needed or omitted. In Figures 6 to 14 and 17, the protective layer 91 and the plasma polymerization layer 92 are not shown.

[0067] As described above, the coating film 80 provided on the spray surface F may be scraped off by external force due to contact with the wiping member 71, the suction member (cap member 72), or the medium M. If the entire coating film 80 is scraped off, there is a risk of malfunction in the liquid spray head 50. For example, if the coating film 80 is a liquid-repellent film, if the entire liquid-repellent film is scraped off, the liquid-repellency near the nozzle will be lost, causing the ink sprayed from the nozzle to bend or mix in color. Also, if ink droplets are attached to the nozzle plate 18c or the surface of the fixing plate 55 facing the spray direction DJ, those ink droplets will be transferred to the medium.

[0068] As shown in Figures 4 to 6, the coating film 80 has a first layer 81a and a second layer 81b. Here, the second layer 81b is located between the first layer 81a and the injection surface F. That is, the second layer 81b overlaps with at least a portion of the first layer 81a when viewed in the Z1 direction, which is the opposite direction to the injection direction DJ. Also, the first layer 81a and the second layer 81b are in contact with each other. Therefore, the coating film 80 has an interface BD between the first layer 81a and the second layer 81b. The interface BD is the interface between the first layer 81a and the second layer 81b that is substantially parallel to the injection surface F and is located furthest in the injection direction DJ. Preferably, the second layer 81b is provided on the injection surface F in a region that is wiped by the wiping member 71 or in a region that contacts the cap member 72.

[0069] As will be explained in detail later, the first layer 81a and the second layer 81b have different colors. As a result, when the coating film 81 is worn down to the interface BD between the first layer 81a and the second layer 81b, the second layer 81b becomes visible at the worn-down area. Therefore, it is possible to detect when the coating film 81 has been worn down to the interface BD between the first layer 81a and the second layer 81b. The details of the first layer 81a and the second layer 81b will be explained in order below.

[0070] The first layer 81a is a layer having higher liquid-repellent properties than the spray surface F. "Liquid-repellent properties" means water repellency when the main component of the liquid is water, and oil repellency when the main component of the liquid is oil, and preferably means that the static contact angle of the liquid is 90 degrees or more.

[0071] The constituent material of the first layer 81a can be any liquid-repellent material and is not particularly limited, but examples include silane coupling agents having fluorine-containing long-chain polymer groups such as perfluoroalkyl chains or perfluoropolyether chains, and fluorine-based resins such as polytetrafluoroethylene (PTFE). However, as will be described later, the first layer 81a may contain a coloring agent as needed. Alternatively, the first layer 81a, which is composed of a silane coupling agent, may be given color properties by introducing substituents that absorb light or have fluorescence as needed.

[0072] The second layer 82b is a layer whose color is different from that of the first layer 81a. "Different color" means that, when visible light is shone onto the liquid spray head 50, at least one difference among hue, lightness, and saturation can be determined visually or by a detector such as a colorimeter.

[0073] More specifically, the color difference between the color of the first layer 81a and the color of the second layer 81b is preferably 12.0 or greater, and more preferably 25 or greater. This allows the difference between the color of the first layer 81a and the color of the second layer 81b to be easily determined by visual inspection. This color difference is, for example, defined by CIE1976 L * a * B *This is the color difference within a color system. The measurement of this color difference is performed, for example, in accordance with JIS Z8730.

[0074] The colors of the first layer 81a and the second layer 81b may be chromatic or achromatic. A chromatic color is a color that has hue, saturation, and lightness. Specific examples of chromatic colors are not limited to JIS safety colors (red, reddish-yellow, yellow, green, blue, reddish-purple), etc. Achromatic colors are colors that lack both hue and saturation. Specific examples of achromatic colors are not limited to JIS safety colors (white, black), etc.

[0075] However, if one of the first layer 81a and the second layer 81b is chromatic and the other is achromatic, the chromatic color will stand out while the achromatic color will not, making it easier to distinguish between the colors of the first layer 81a and the second layer 81b. From the viewpoint that it is easier to detect whether or not the second layer 81b is exposed if the color of the second layer 81b is more noticeable than the color of the first layer 81a when the second layer 81b is exposed, it is preferable that the color of the second layer 81b is chromatic and the color of the first layer 81a is achromatic.

[0076] The constituent material of the second layer 81b is not particularly limited, as long as the colors of the first layer 81a and the second layer 81b are different from each other, but it is preferable to use a material that has liquid-repellent properties similar to the first layer 81a. That is, it is preferable that the second layer 81b has higher liquid-repellent properties than the spray surface F. This prevents liquid from adhering to the second layer 81b even when the coating film 81 is scraped down to the boundary between the first layer 81a and the second layer 81b, while the second layer 81b remains exposed. When the second layer 81b has liquid-repellent properties, it may be difficult to deposit the first layer 81a on the surface of the second layer 81b. In such cases, the first layer 81a can be firmly bonded by depositing an SiO2 film on the surface of the second layer 81b and then depositing the first layer 81a on the surface of the SiO2 film. This allows the first layer 81a and the second layer 81b to be laminated. When forming the second layer 82b, a thin film can be deposited by vacuum deposition or inkjet printing. When forming the film by vacuum deposition, a metal may be used as the constituent material for the second layer 81b.

[0077] The constituent materials of the first layer 81a and the constituent materials of the second layer 81b, or both, may contain a coloring agent as needed. If at least one of the first layer 81a and the second layer 81b contains a coloring agent, the difference in color between the first layer 81a and the second layer 81b can be easily adjusted by the type, presence, or amount of the coloring agent. Adjusting the difference in color between the first layer 81a and the second layer 81b does not necessarily require the use of a coloring agent; it may also be adjusted by changing the reflectance, transmittance, or hue through chemical composition or state.

[0078] Colorants are not particularly limited, but examples include various pigments and various dyes.

[0079] Examples of pigments include CI Pigment Red 2, 3, 5, 17, 22, 23, 38, 81, 48:1, 48:2, 48:3, 48:4, 49:1, 52:1, 53:1, 57:1, 63:1, 112, 122, 144, 146, 149, 166, 170, 176, 177, 178, 179, 185, 202. ,207,209,254,101,102,105,106,108,108:1, CI Pigment Green 7,36,15,17,18,19,26,50, CI Pigment Blue 1,15,15:1,15:2,15:3,15:4,15:6,17:1,18,60,27,28,29,35,36 Examples include CI Pigment Yellow 1,3,12,13,14,17,55,73,74,81,83,93,94,95,97,108,109,110,129,138,139,150,151,153,154,168,184,185,34,35,35:1,37,37:1,42,43,53,157, CI Pigment Violet 1,3,19,23,50,14,16, CI Pigment Orange 5,13,16,36,43,20,20:1,104, CI Pigment Brown 25,7,11,33, etc., and one of these can be used alone or in combination of two or more.

[0080] Examples of dyes include azo dyes, anthraquinone dyes, condensed polycyclic aromatic carbonyl dyes, indigoid dyes, carbonium dyes, phthalocyanine dyes, methine, and polymethine dyes. Specific examples of dyes include CI Direct Red 2, 4, 9, 23, 26, 28, 31, 39, 62, 63, 72, 75, 76, 79, 80, 81, 83, 84, 89, 92, 95, 111, 173, 184, 207, 211, 2 12,214,218,221,223,224,225,226,227,232,233,240,241,242,243,247, CI Acid Red 35,42,51,52,57,62,80,82,111,114,118,119,127,128,131,143,145,151,154,157,158,211,249,254,257,261,263,266,289,299,301,305,319,336,337,361,396,397, CI Reactive Red 3,13,17,19, 21,22,23,24,29,35,37,40,41,43,45,49,55, CI Basic Red 12,13,14,15,18,22,23,24,25,27,29,35,36,38,39,45,46, CI Direct Violet 7,9,47,48,51,66,90,93,94,95,98,100,101, CI Acid Violet 5,9,11,34,43,47,48,51,75,90,103,126, CI Reactive Violet 1,3,4,5,6,7,8,9,16,17,22, 23,24,26,27,33,34, CI Basic Violet 1,2,3,7,10,15,16,20,21,25,27,28,35,37,39,40,48, CI Direct Yellow 8,9,11,12,27,28,29,33,35,39,41,44,50,53,58,59,68,87,93,95,96,98,100,106,108,109,110,130,142,144,161,163, CI Acid Yellow 17,19,23,25,39,40,42,44,49,50,61,64, 76, 79, 110, 127, 135, 143, 151, 159, 169, 174, 190, 195, 196, 197, 199, 218, 219, 222, 227, CI Reactive Yellow 2, 3, 13, 14, 15, 17, 18, 23, 24, 25, 26, 27, 29, 35, 37, 41, 42, CI Basic Yellow 1, 2, 4, 11, 13, 14, 15, 19, 21, 23, 24, 25, 28, 29, 32, 36, 39, 40, CI Acid Green 16, CI Acid Blue 9, 45, 80, 83, 90, 185, CIExamples include Basic Orange 21 and 23, and these can be used individually or in combination of two or more.

[0081] The amount of coloring agent in the coating film 80 is not particularly limited, as long as it is in an amount that does not cause the coating film 80 to fail to harden properly.

[0082] When both the first layer 81a and the second layer 81b contain a coloring agent, it is preferable that the color of the coloring agent in the first layer 81a is different from the color of the coloring agent in the second layer 81b. This makes it easy to adjust the color difference between the first layer 81a and the second layer 81b depending on the type of coloring agent.

[0083] Here, the first layer 81a, which forms the surface of the coating film 80, is opaque. That is, when the surface of the coating film 80 is viewed in the opposite direction to the injection direction DJ, the second layer 81b, which forms the deeper layers of the coating film 80, is not visible. Alternatively, the second layer 81b, which forms the deeper layers of the coating film 80, may be colorless and transparent. In this case, the difference in color between the first layer 81a, which forms the surface of the coating film 80, and the color of the injection surface F is used to determine whether or not the second layer 81b is exposed and to predict the lifespan. Therefore, the color of the injection surface F and the color of the first layer 81a, which forms the surface of the coating film 80, must be different.

[0084] It is preferable that the components of the first layer 81a, excluding the coloring agent, and the components of the second layer 81b, excluding the coloring agent, are the same. This substantially eliminates the difference in the coefficient of linear expansion between the first layer 81a and the second layer 81b. As a result, peeling of the coating film 80 caused by this difference in coefficient of linear expansion can be reduced. Conversely, the larger the difference in the coefficient of linear expansion, the greater the stress difference between the first layer 81a and the second layer 81b when a temperature change occurs, making the coating film 80 more prone to peeling. For the same reason, it is preferable that the coefficient of linear expansion of the first layer 81a and the coefficient of linear expansion of the second layer 81b are equal.

[0085] The coloring agent is preferably a dye. This is because the dye particles are smaller than those of a pigment, thus reducing the degree of adverse effects such as damage to the wiping member 71, damage to the nozzle plate 18c due to particles adhering to the nozzle plate 18c being rubbed against the wiping member 71, and poor discharge due to particle accumulation in the nozzle. In addition, the small size of the coloring agent particles makes it easier to form a thin coating film 80. Note that the coloring agent is not limited to dyes and may also be a pigment.

[0086] At least one of the second layer 81b and the first layer 81a may contain a phosphor that emits light upon ultraviolet irradiation as a coloring agent. In this case, by irradiating the coating film 80 with ultraviolet light, one or both of the first layer 81a and the second layer 81b can be made to emit light. At this time, the difference between the color of the first layer 81a and the color of the second layer 81b can be determined based on the presence or absence of light emission or the difference in the color of the emitted light between the first layer 81a and the second layer 81b.

[0087] Phosphors are, for example, fluorescent pigments or fluorescent dyes, specifically CI Disperse Red 364, CI Disperse Red 362, CI Batt Red 41, CI Disperse Yellow 232, CI Disperse Yellow 184, CI Disperse Yellow 82, CI Disperse Yellow 43, and the like.

[0088] In the region of the coating film 80 that overlaps with the second layer 81b and the injection direction DJ, it is preferable that the distance D1 from the surface Fa of the coating film 80 facing the injection direction DJ to the interface BD is smaller than the distance D2 from the interface BD to the injection surface F. This ensures that when the coating film 80 is scraped down to the interface BD, more than half of the total thickness of the coating film 80 remains. Therefore, it is possible to detect the possibility of a malfunction occurring early, before the entire coating film 80 peels off and a malfunction occurs.

[0089] The distance D2 in the injection direction DJ from the interface BD to the injection surface F may be twice or more than three times the distance D1 in the injection direction DJ from the surface Fa of the coating film 80 facing the injection direction DJ to the interface BD. Furthermore, the distance D1 in the injection direction DJ from the surface Fa of the coating film 80 facing the injection direction DJ to the interface BD may be greater than the distance D2 in the injection direction DJ from the interface BD to the injection surface F. In this case, the coating film 80 can be utilized to its maximum extent.

[0090] As shown in Figure 4, the injection surface F includes a nozzle formation region RN where multiple nozzles N are formed. The nozzle formation region RN is a region on the surface of the nozzle plate 18c and is the smallest rectangular region encompassing the nozzle rows La and Lb. Therefore, the nozzle formation region RN does not exist on the fixed plate 55.

[0091] Here, the second layer 81b is positioned outside the nozzle formation region RN. When viewed in the opposite direction to the injection direction DJ, if the second layer 81b is located around the opening of the nozzle N, the coating film 80 of the second layer 81b becomes thicker, increasing the distance in the injection direction DJ to the opening of the nozzle N, which may adversely affect the discharge characteristics. However, by positioning the second layer 81b outside the nozzle formation region RN, the second layer 81b is positioned away from the nozzle N, thus suppressing this adverse effect. Furthermore, if the second layer 81b does not have liquid-repellent properties, and liquid-repellent properties are lost around the nozzle N, problems such as flight deviation or color mixing are likely to occur. Therefore, from the viewpoint of suppressing such problems, it is preferable to position the second layer 81b outside the nozzle formation region RN. Moreover, it is preferable that the second layer 81b is provided in a region along the direction in which the wiping member 71 wipes relative to the nozzle formation region RN. In this embodiment, since the wiping direction of the wiping member 71 is the Y2 direction, it is preferable that the second layer 81b be provided in a region aligned with the Y2 direction relative to the nozzle formation region RN. This is because, when the ink ejected from the nozzle contains pigment, the region aligned with the wiping direction of the wiping member 71 relative to the nozzle formation region RN is prone to having the coating film 80 scraped off by the wiping member rubbing the pigment-containing ink.

[0092] Thus, in this embodiment, the second layer 81b is not present on the fixing plate 55, but is provided only on the nozzle plate 18c. This allows for the detection of the degree of deterioration of the coating film 81 provided on the nozzle plate 18c, thereby effectively suppressing adverse effects on discharge characteristics due to abrasion of the coating film 81. Furthermore, since the formation of the coating film 80 only requires processing of the nozzle plate 18c, manufacturing becomes easier.

[0093] Note that the arrangement of the second layer 81b is not limited to the example shown in Figure 4; for example, it may be on the fixing plate 55 as in the eighth embodiment described later, or it may be between the nozzle row La and the nozzle row Lb.

[0094] Figure 6 is an explanatory diagram of the exposed state of the second layer 81b of the coating film 81. As shown in Figure 6, when the coating film 81 is worn down to the interface BD between the first layer 81a and the second layer 81b, the second layer 81b becomes visible at the worn-down area. Therefore, it is possible to detect, either visually or by the detection unit 74, that the coating film 81 has been worn down to the interface between the first layer 81a and the second layer 81b. Thus, the near end of the coating film 81 can be detected before the entire coating film 81 is worn away, which would cause a malfunction in the liquid spray head 50. In other words, the lifespan of the coating film 81 can be predicted.

[0095] Since the lifespan of the coating film 80 can be predicted in this way, the liquid spray head 50 can be replaced at the appropriate time to prevent malfunctions during use, thereby suppressing problems such as downtime required to prepare a replacement liquid spray head 50 or wasting ink or media.

[0096] 2. Second Embodiment The following describes a second embodiment of this disclosure. For elements whose operation and function are the same as in the first embodiment in the embodiments described below, the reference numerals used in the description of the first embodiment will be reused, and detailed descriptions of each will be omitted as appropriate.

[0097] The coating film 81A is configured in the same way as the coating film 81 of the first embodiment, except that a third layer 81c has been added.

[0098] The third layer 81c is positioned between the second layer 81b and the injection surface F, and is configured similarly to the second layer 81b, except that it is a different color from the first layer 81a and the second layer 81b.

[0099] Figure 8 is a schematic cross-sectional view of the coating film 81A in the second embodiment. Figure 9 is an explanatory diagram of the exposed state of the second layer 81b of the coating film 81A. Figure 10 is an explanatory diagram of the exposed state of the third layer 81c of the coating film 81A.

[0100] In this embodiment, as shown in Figure 9, similar to the first embodiment, when the coating film 81A is worn down to the boundary between the first layer 81a and the second layer 81b, as shown in Figure 10, when the coating film 81A is worn down to the boundary between the second layer 81b and the third layer 81c, the third layer 81c becomes visible at the worn-down location. Therefore, it is possible to detect when the coating film 81A has been worn down to the boundary between the second layer 81b and the third layer 81c. In this way, the near end of the coating film 81A can be detected in stages before the liquid spray head 50 malfunctions due to the complete wear of the coating film 81A. In other words, the lifespan of the coating film 81A can be predicted in stages.

[0101] 3. Third Embodiment A third embodiment of this disclosure will be described below. For elements whose operation and function are the same as in the first embodiment in the embodiments described below, the reference numerals used in the description of the first embodiment will be reused, and detailed descriptions of each will be omitted as appropriate.

[0102] Figure 11 is a schematic cross-sectional view of the coating film 81B in the third embodiment. The coating film 81B is configured similarly to the coating film 81 of the first embodiment, except that the stacking order of the first layer 81a and the second layer 82b is reversed compared to the first embodiment.

[0103] In this type of coating 81B, when the coating 81B is worn down to the boundary between the first layer 81a and the second layer 81b, the second layer 81b becomes invisible at the worn-down area. Therefore, it is possible to detect when the coating 81B has been worn down to the boundary between the first layer 81a and the second layer 81b. Consequently, the near end of the coating 81B can be detected before the coating 81B is completely worn down, which would cause a malfunction in the liquid spray head 50. In other words, the lifespan of the coating 81B can be predicted.

[0104] 4. Fourth Embodiment A fourth embodiment of this disclosure will now be described. For elements whose operation and function are the same as in the first embodiment in the embodiments described below, the reference numerals used in the description of the first embodiment will be reused, and detailed descriptions of each will be omitted as appropriate.

[0105] Figure 12 is a schematic cross-sectional view of the coating film 81C in the fourth embodiment. The coating film 81C is configured similarly to the coating film 81 of the first embodiment, except that the second layer 81b is positioned midway along the thickness direction of the first layer 81a.

[0106] In this type of coating film 81C, as in the first embodiment, when the coating film 81C is worn down to the boundary between the first layer 81a and the second layer 81b, the second layer 81b becomes visible at the worn-down area. Therefore, it is possible to detect when the coating film 81C has been worn down to the boundary between the first layer 81a and the second layer 81b. Consequently, the near end of the coating film 81C can be detected before the coating film 81C is completely worn down, which would cause a malfunction in the liquid spray head 50. In other words, the lifespan of the coating film 81C can be predicted.

[0107] Furthermore, since the second layer 81b is positioned midway along the thickness of the first layer 81a, even if the second layer 81b is completely worn away, the liquid-repellent properties of the first layer 81a can still be maintained.

[0108] 5. Fifth Embodiment The fifth embodiment of this disclosure will now be described. For elements whose operation and function are the same as in the first embodiment in the embodiments described below, the reference numerals used in the description of the first embodiment will be reused, and detailed descriptions of each will be omitted as appropriate.

[0109] Figure 13 is a schematic cross-sectional view of the coating film 81D in the fifth embodiment. The coating film 81D is configured in the same way as in the first embodiment, except that a third layer 81d is provided between the first layer 81a and the second layer 81b, and the first layer 81a, the second layer 81b, and the third layer 81d are provided over the entire surface F of the spray surface. In other words, if there is no fixing plate 55, the first layer 81a, the second layer 81b, and the third layer 81d are provided over the entire surface FN of the nozzle plate 18c, and if there is a fixing plate 55, the first layer 81a, the second layer 81b, and the third layer 81d are provided over the entire surface FN of the nozzle plate 18c and the entire surface FF of the fixing plate 55 facing the Z2 direction.

[0110] Here, it is preferable that the third layer 81d is a different color from the first layer 81a and the second layer 81b, similar to the third layer 81c in the second embodiment. This makes it possible to predict the lifespan of the coating film 81D in stages, similar to the second embodiment.

[0111] Furthermore, it is preferable that the third layer 81d has liquid-repellent properties similar to the first layer 81a. This allows the liquid-repellent properties of the third layer 81d to be maintained even if the second layer 81b is completely worn away, as in the fourth embodiment.

[0112] As described above, by providing the second layer 81b across the entire surface of the spray surface F, the lifespan of the coating film 81D can be detected regardless of where an abnormality occurs on the spray surface F. Furthermore, when the second layer 81b is provided across the entire surface of the nozzle surface FN of the nozzle plate 18c and the surface FF of the fixing plate 55 facing the Z2 direction, abnormalities in the coating film 81D can be detected at both the fixing plate 55, which is prone to wear due to strong contact with the wiping member 71, and the nozzle plate 18c, which has a significant direct impact on discharge.

[0113] Furthermore, if the second layer 81b is provided on the entire surface of the nozzle surface FN of the nozzle plate 18c and the surface FF of the fixing plate 55 facing the Z2 direction, the second layer 81b must be liquid-repellent. This allows the second layer 81b to exhibit liquid-repellent properties even when it is exposed.

[0114] The lifespan of the coating film 81D can also be predicted by the fifth embodiment described above.

[0115] 6. Sixth Embodiment The sixth embodiment of this disclosure will now be described. For elements whose operation and function are the same as in the first embodiment in the embodiments described below, the reference numerals used in the description of the first embodiment will be reused, and detailed descriptions of each will be omitted as appropriate.

[0116] Figure 14 is a schematic cross-sectional view of the coating film 81E in the sixth embodiment. Figure 15 is a plan view of the coating film 81E shown in Figure 14, in which the second layer 81b is covered by the first layer 81a. Figure 16 is a plan view of the coating film 81E shown in Figure 14, in which the second layer 81b is exposed from the first layer 81a. Note that in Figure 15, for the sake of explanation, the shape of the second layer 81b is shown with a dashed line, but in reality, the second layer 81b is not visible when it is covered by the first layer 81a.

[0117] The coating film 81E is configured similarly to the coating film 81C of the fourth embodiment, except that the shape of the second layer 81b when viewed along the Z-axis is different.

[0118] In this embodiment, the second layer 81b is a mark that indicates when it is time to replace the liquid spray head 50, when viewed in the opposite direction of the spray direction DJ. This makes it easier for the user to detect that the lifespan of the coating film 81E is nearing its end when the characters or marks on the second layer 81b become visible, as in this embodiment when the second layer 81b is initially covered by the first layer 81a. Note that the mark displayed on the second layer 81b is not limited to the illustrated example and is arbitrary. The second layer 81b may also display characters that indicate when it is time to replace the liquid spray head 50.

[0119] The lifespan of the coating film 81E can also be predicted by the sixth embodiment described above.

[0120] 7. Seventh Embodiment The following describes a seventh embodiment of this disclosure. For elements whose operation and function are the same as in the first embodiment in the embodiments described below, the reference numerals used in the description of the first embodiment will be reused, and detailed descriptions of each will be omitted as appropriate.

[0121] Figure 17 is a schematic cross-sectional view of the coating film 81F in the seventh embodiment. Figure 18 is a plan view of the coating film 81F shown in Figure 17 with the second layer 81b remaining. Figure 19 is a plan view of the coating film 81F shown in Figure 17 with the second layer 81b gone. Note that in Figure 19, for the sake of explanation, the shape of the second layer 81b is shown by a dashed line, but in reality, the second layer 81b is not visible when it has disappeared.

[0122] The coating film 81F is configured similarly to the coating film 81B of the third embodiment, except that the shape of the second layer 81b when viewed along the Z-axis is different.

[0123] In this embodiment, the second layer 81b is a mark that indicates when the liquid spray head 50 should be replaced, when viewed in the opposite direction of the spray direction DJ. This allows the user to detect that the lifespan of the coating film 81F is nearing its end when the letters or mark disappear, provided that the second layer 81b is exposed from the beginning, as in this embodiment. The mark displayed on the second layer 81b is not limited to the illustrated example and is arbitrary. Furthermore, the second layer 81b may display letters indicating when the liquid spray head 50 should be replaced.

[0124] The lifespan of the coating film 81F can also be predicted by the seventh embodiment described above.

[0125] 8. Eighth Embodiment The following describes an eighth embodiment of this disclosure. For elements whose operation and function are the same as in the first embodiment in the embodiments described below, the reference numerals used in the description of the first embodiment will be reused, and detailed descriptions of each will be omitted as appropriate.

[0126] Figure 20 is a schematic diagram showing an example of the configuration of the liquid injection device 100G according to the eighth embodiment. Figure 21 is a bottom view of the liquid injection head 50G according to the eighth embodiment. The liquid injection device 100G is configured in the same way as the liquid injection device 100 of the first embodiment, except that it includes a liquid injection head 50G instead of the liquid injection head 50 of the first embodiment, a sensor 73G instead of the sensor 73 of the first embodiment, and a wiping member 71G instead of the wiping member 71 of the first embodiment.

[0127] The wiping member 71G is made of an elastic material such as rubber, has a long shape extending along the Y-axis, and is an elastic member such as a blade-shaped rubber member that protrudes in the Z1 direction. The wiping member 71G is positioned off-center along the X-axis relative to the transport area of ​​the medium M. When the wiping member 71G wipes the nozzle plate 18c or the fixing plate 55, the moving mechanism 40 moves the liquid spray head 50 to a position that overlaps with the wiping member 71G when viewed along the Z-axis, as shown in Figure 21. This performs wiping or cleaning of the nozzle plate 18c or the fixing plate 55 by wiping with the wiping member 71.

[0128] The liquid spray head 50G is configured in the same way as the liquid spray head 50 of the first embodiment, except that it is equipped with a coating film 80G instead of the coating film 80. The coating film 80G is divided into a coating film 81G and a coating film 82G. The coating film 81G is configured in the same way as the coating film 81 of the first embodiment, except that the second layer 81b is omitted.

[0129] The coating film 82G has a layer structure similar to the coating film 81 of the first embodiment, and comprises a first layer 82a and a second layer 82b. The first layer 82a is configured similarly to the first layer 81a of the first embodiment, except that it is provided on the fixing plate 55. The second layer 82b is configured similarly to the second layer 81b of the first embodiment, except that it is provided on the fixing plate 55.

[0130] Thus, in this embodiment, the second layer 82b is not provided on the nozzle plate 18c, but on the fixing plate 55. Here, the second layer 82b is aligned in a direction along the X-axis with respect to the nozzle forming region RN.

[0131] Sensor 73G is configured similarly to sensor 73 in the first embodiment, except that it consists of one sensor corresponding to the arrangement of the second layer 82b. Here, sensor 73G and determination unit 21 constitute detection unit 74G that detects whether or not the second layer 82b is exposed.

[0132] The coating film 82G on the fixed plate 55 is subjected to greater contact force with the wiping member 71G than the coating film 81G on the nozzle plate 18c, and is therefore more easily rubbed. In contrast, in this embodiment, by providing a second layer 82b on the fixed plate 55, the lifespan can be predicted before problems such as loss of liquid repellency near the nozzle N, resulting in flight deviation or color mixing, occur.

[0133] Furthermore, in this embodiment, there is no need to provide a second layer 81b on the nozzle plate 18c, which simplifies manufacturing.

[0134] The lifespan of the coating film 82G can also be predicted by the eighth embodiment described above.

[0135] 9. Variations The forms exemplified above can be modified in various ways. Specific examples of modifications that can be applied to the aforementioned forms are given below. Two or more forms arbitrarily selected from the following examples can be merged as appropriate, provided they do not contradict each other.

[0136] 9-1. Variation 1 In the embodiments described above, a configuration in which the liquid spray head has two head tips is exemplified. However, the configuration does not have to be this one, and the number of head tips in the liquid spray head may be one or less, or three or more. Furthermore, when the liquid spray head has multiple head tips, the arrangement of these multiple head tips is not limited to the embodiments described above and is arbitrary. Also, the shape of the liquid spray head is not limited to the embodiments described above and is arbitrary.

[0137] 9-2. Variation 2 In the above-described embodiment, a serial-type liquid injection device 100 was illustrated in which a transporter 41 equipped with a liquid injection head 50 is reciprocated in the width direction of the medium M. However, the liquid injection device may also be a line-type device in which a plurality of nozzles N are distributed across the entire width of the medium M.

[0138] 9-3. Variation 3 The liquid spraying devices exemplified in the above-described form can be used in various devices such as facsimile machines and photocopiers, in addition to equipment dedicated to printing. However, the applications of liquid spraying devices are not limited to printing. For example, liquid spraying devices that spray colorant solutions are used as manufacturing equipment to form color filters for display devices such as liquid crystal display panels. Liquid spraying devices that spray conductive material solutions are used as manufacturing equipment to form wiring and electrodes on wiring boards. Furthermore, liquid spraying devices that spray solutions of organic substances related to living organisms are used, for example, as manufacturing equipment to produce biochips.

[0139] 10. Addendum A summary of this disclosure is provided below.

[0140] (Note 1) A first embodiment of a preferred example of a liquid spray head of the present disclosure is a liquid spray head comprising: a plurality of nozzles for spraying liquid in the spraying direction; a spraying surface which is a surface facing the spraying direction; and a coating film provided on the spraying surface, wherein the coating film comprises a first layer having higher liquid repellency than the spraying surface and a second layer which is a different color from the first layer, and the second layer overlaps with at least a portion of the first layer when viewed in the opposite direction to the spraying direction.

[0141] In the above embodiment, when the coating film is worn down to the boundary between the first and second layers, the second layer will either become visible or completely obscured at the worn-down area. Therefore, it is possible to detect when the coating film has been worn down to the boundary between the first and second layers. Consequently, the near end of the coating film can be detected before the liquid spray head malfunctions due to the complete wear of the coating film. In other words, the lifespan of the coating film can be predicted.

[0142] (Note 2) In a second embodiment, which is a preferred example of the first embodiment, the second layer has higher liquid-repellent properties than the spray surface. In this embodiment, even when the second layer is exposed, it is possible to prevent liquid from adhering to the second layer.

[0143] (Note 3) In a third embodiment, which is a preferred example of the first or second embodiment, the second layer is a letter or mark that indicates when it is time to replace the liquid spray head, when viewed in the opposite direction to the spray direction. In the above embodiments, when the second layer is covered by the first layer, the user can easily detect that the lifespan of the coating is nearing its end when the letter or mark becomes visible. When the second layer is exposed from the beginning, the user can detect that the lifespan of the coating is nearing its end when the letter or mark becomes invisible.

[0144] (Note 4) In a fourth embodiment, which is a preferred example of any of the first to third embodiments, the coating film has an interface between the first layer and the second layer that is substantially parallel to the injection surface and is located furthest in the injection direction, and in the region of the coating film that overlaps with the second layer in the injection direction, the distance in the injection direction from the surface of the coating film facing the injection direction to the interface is smaller than the distance in the injection direction from the interface to the injection surface. In the above embodiments, when the coating film is scraped down to the interface, more than half of the total thickness of the coating film remains. Therefore, it is possible to detect the possibility of a malfunction occurring early, before the entire coating film peels off and a malfunction occurs.

[0145] (Note 5) In the fifth embodiment, which is a preferred example of any of the first to fourth embodiments, at least one of the first layer and the second layer contains a coloring agent. In the above embodiments, the difference in color between the first layer and the second layer can be easily adjusted by the type, presence or absence, or content of the coloring agent.

[0146] (Note 6) In the sixth embodiment, which is a preferred example of the fifth embodiment, each of the first and second layers contains a coloring agent, and the color of the coloring agent contained in the first layer is different from the color of the coloring agent contained in the second layer. In the above embodiments, the difference in color between the first and second layers can be easily adjusted by the type of coloring agent.

[0147] (Note 7) In the seventh embodiment, which is a preferred example of the fifth embodiment, the coloring agent is a dye. In the above embodiments, since the dye particles are smaller than the pigment particles, the degree of adverse effects such as damage to the wiping member, damage to the nozzle plate due to particles on the nozzle plate being rubbed against the wiping member, and poor discharge due to accumulation of particles in the nozzle can be reduced. In addition, since the coloring agent particles are small, there is also the advantage that the coating film can be made thin.

[0148] (Note 8) In the eighth embodiment, which is a preferred example of the fifth embodiment, the components of the first layer excluding the colorant and the components of the second layer excluding the colorant are the same. In the above embodiment, the difference in the coefficient of linear expansion between the first layer and the second layer can be substantially eliminated. Therefore, peeling of the coating film caused by the difference in the coefficient of linear expansion can be reduced. On the other hand, the larger the difference in the coefficient of linear expansion, the larger the difference in the amount of shrinkage due to hardening between the first layer and the second layer becomes, so the coating film becomes more prone to peeling due to the stress difference between the first layer and the second layer.

[0149] (Note 9) In the ninth embodiment, which is a preferred example of any of the first to eighth embodiments, a nozzle plate is provided that includes at least a part of the spray surface and has the plurality of nozzles, wherein the spray surface includes a nozzle forming region in which the plurality of nozzles are formed, and the second layer is positioned outside the nozzle forming region. In the above embodiments, if the second layer is located around the nozzle opening when viewed in the opposite direction to the spray direction, the coating film becomes thicker, which increases the distance in the spray direction to the discharge opening, potentially adversely affecting the discharge characteristics. However, by positioning the second layer outside the nozzle forming region, the second layer is positioned away from the nozzle, thus suppressing this adverse effect. Furthermore, if the second layer does not have liquid-repellent properties, and liquid-repellent properties are lost around the nozzle, problems such as flight deviation or color mixing are likely to occur. Therefore, from the viewpoint of suppressing such problems, it is preferable to position the second layer outside the nozzle forming region.

[0150] (Note 10) In the tenth embodiment, which is a preferred example of any of the first to ninth embodiments, the device comprises a fixing plate having an opening for exposing the plurality of nozzles and at least a part of the spray surface, wherein the second layer is provided on the fixing plate. In the above embodiments, the coating film on the fixing plate is more susceptible to abrasion than the coating film on the nozzle plate because it is subjected to a greater force when the wiping member strikes it than the coating film on the nozzle plate. In contrast, by providing the second layer on the fixing plate, the lifespan can be predicted before problems such as flight deviation or color mixing occur due to the loss of liquid repellency near the nozzles.

[0151] (Note 11) In the 11th embodiment, which is a preferred example of the 10th embodiment, a nozzle plate having the plurality of nozzles is provided, and the second layer is not provided on the nozzle plate. In the above embodiments, it is not necessary to provide the second layer on the nozzle plate, so manufacturing is simplified.

[0152] (Note 12) In the twelfth embodiment, which is a preferred example of any of the first to eleventh embodiments, the second layer is provided over the entire surface of the spray surface. In this embodiment, the lifespan of the coating can be detected regardless of where an abnormality occurs on the spray surface. Furthermore, abnormalities in the coating can be detected at both the fixing plate, which is in strong contact with the wiping member and is prone to abrasion, and the nozzle plate, which has a significant direct impact on discharge.

[0153] (Note 13) A thirteenth embodiment, which is a preferred example of the liquid injection device of the present disclosure, comprises a liquid injection head according to any of the first to twelfth embodiments, and a detection unit for detecting whether or not the second layer is exposed.

[0154] In the above embodiment, the detection unit can confirm whether or not the second layer is exposed. Therefore, the effort required for visual inspection is eliminated. Furthermore, compared to visual inspection, the detection capability or resolution of the color difference is higher, resulting in higher detection accuracy. As a result, the degree of freedom in the colors of the first and second layers can be increased, and the size of the marks or letters can be reduced. [Explanation of Symbols]

[0155] 10...Liquid container, 18a...Communication plate, 18b...Pressure chamber substrate, 18c...Nozzle plate, 18d...Compliance substrate, 18d1...Compliance film, 18d2...Frame, 18e...Diaphragm, 18g...Cover, 18h...Case, 18i...Wiring board, 18j...Drive circuit, 20...Control unit, 21...Determination unit, 30...Transport mechanism, 40...Moving mechanism, 41...Transport body, 42...Transport belt, 50...Liquid injection head, 50G...Liquid injection head, 51...Flow channel structure, 51a...Connecting pipe, 51b...Wiring hole, 52... Board unit, 52a...Circuit board, 52b...Connector, 52c...Wiring, 52d...Wiring hole, 53...Holder, 53a...Recess, 53b...Wiring hole, 54...Head chip, 54-1...Head chip, 54-2...Head chip, 54i...Wiring board, 54j...Drive circuit, 55...Fixing plate, 55a...Opening, 55a-1...Opening, 55a-2...Opening, 60...Notification unit, 71...Wiping member, 71G...Wiping member, 72...Cap member, 73...Sensor, 73G...Sensor, 74...Detection unit, 74G...Detection unit, 80...Coating film, 80G...Coating film, 81...Coating film, 81A...Coating film, 81B...Coating film, 81C...Coating film, 81D...Coating film, 81E...Coating film, 81F...Coating film, 81G...Coating film, 81a...First layer, 81b...Second layer, 81c...Third layer, 81d...Third layer, 82...Coating film, 82G...Coating film, 82a...First layer, 82b...Second layer, 91...Protective layer, 100...Liquid injection device, 100G...Liquid injection device, B...Sealing material, BD...Interface, Ca...Pressure chamber, Cb...Pressure chamber, D...Drive signal, D1...Distance, D2...Distance, DJ...Injection direction, DM... Conveying direction, Ea...driving element, Eb...driving element, F...injection surface, FF...surface, FN...nozzle surface, Fa...surface, La...nozzle row, Lb...nozzle row, M...medium, N...nozzle, NRa...communicating channel, NRb...communicating channel, R1a...space, R1b...space, R2a...space, R2b...space, RN...nozzle formation region, RRa...supply channel, RRb...supply channel, Ra...liquid storage chamber, Ra_in...inlet, Rb...liquid storage chamber, Rb_in...inlet, Rca...compliance space, Rcb...compliance space, S...control signal.

Claims

1. A liquid spray head, Multiple nozzles that spray liquid in the direction of injection, The injection surface is the surface facing the injection direction, The coating film provided on the injection surface, Equipped with, The aforementioned coating film is A first layer having higher liquid-repellent properties than the aforementioned spray surface, It has a second layer which is a different color from the first layer, The second layer overlaps with at least a portion of the first layer when viewed in the direction opposite to the injection direction. A liquid spray head characterized by the following features.

2. The second layer has higher liquid-repellent properties than the spray surface. The liquid spray head according to feature 1.

3. The second layer, when viewed in the opposite direction to the spray direction, is a letter or mark indicating when it is time to replace the liquid spray head. The liquid spray head according to feature 1.

4. The coating film has an interface between the first layer and the second layer that is substantially parallel to the injection surface and is located most in the direction of injection. In the region of the coating film that overlaps with the second layer in the injection direction, the distance in the injection direction from the surface of the coating film facing the injection direction to the interface is smaller than the distance in the injection direction from the interface to the injection surface. The liquid spray head according to feature 1.

5. At least one of the first layer and the second layer contains a coloring agent. The liquid spray head according to feature 1.

6. Each of the first and second layers contains a coloring agent, The color of the coloring agent contained in the first layer is different from the color of the coloring agent contained in the second layer. The liquid spray head according to feature 5.

7. The aforementioned coloring agent is a dye. The liquid spray head according to feature 5.

8. The components of the first layer excluding the coloring agent and the components of the second layer excluding the coloring agent are the same as each other. The liquid spray head according to feature 5.

9. A nozzle plate comprising at least a portion of the spray surface and having the plurality of nozzles, The injection surface includes a nozzle forming region in which the plurality of nozzles are formed. The second layer is positioned outside the nozzle forming region. The liquid spray head according to feature 1.

10. The device comprises a fixing plate having an opening for exposing the plurality of nozzles and at least a portion of the spray surface, The second layer is provided on the fixing plate, The liquid spray head according to feature 1.

11. The nozzle plate comprises the plurality of nozzles, The second layer is not provided on the nozzle plate. The liquid spray head according to claim 10.

12. The second layer is provided over the entire surface of the injection surface, The liquid spray head according to feature 1.

13. The liquid spray head according to claim 1, A detection unit for detecting whether or not the second layer is exposed, A liquid injection device characterized by being equipped with the following features.

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