WO2020203907A1

WO2020203907A1 - Liquid ejecting head and recording device

Info

Publication number: WO2020203907A1
Application number: PCT/JP2020/014355
Authority: WO
Inventors: 吉田　真人
Original assignee: 京セラ株式会社
Priority date: 2019-03-29
Filing date: 2020-03-27
Publication date: 2020-10-08
Also published as: JP7216194B2; JPWO2020203907A1

Abstract

A liquid ejecting head according to an embodiment of the present invention is provided with a flow passage member, a pressurizing portion, and a plurality of ejection holes. The flow passage member has a first surface and a second surface positioned on the opposite side to the first surface. The pressurizing portion is positioned on the first surface. The plurality of ejection holes are positioned in the second surface. The flow passage member has a water repellent film on the second surface. The water repellent film has protruding portions which protrude in a first direction, where the first direction is defined as the direction from the first surface toward the second surface. The protruding portions are positioned at the periphery of the ejection holes in a plan view of the second surface, and have an annular or arcuate shape in a plan view.

Description

Liquid discharge head and recording device

The disclosed embodiment relates to a liquid discharge head and a recording device.

As a printing device, an inkjet printer or an inkjet plotter using an inkjet recording method is known. Such an inkjet printing apparatus is equipped with a liquid ejection head for ejecting a liquid.

The liquid discharge head includes a flow path member having a plurality of discharge holes. Some flow path members have a protrusion around the ejection hole in order to stabilize the ink ejection direction (see, for example, Patent Document 1).

JP-A-2007-69381

The liquid discharge head according to one aspect of the embodiment includes a flow path member, a pressurizing portion, and a plurality of discharge holes. The flow path member has a first surface and a second surface located on the opposite side of the first surface. The pressurizing portion is located on the first surface. The plurality of discharge holes are located on the second surface. The flow path member has a water-repellent film on the second surface. The water-repellent film has a convex portion protruding in the first direction when the direction from the first surface to the second surface is the first direction. The convex portion is located around the discharge hole in the plan view of the second surface, and the shape in the plan view is annular or arcuate.

FIG. 1 is an explanatory diagram (No. 1) of the recording device according to the embodiment. FIG. 2 is an explanatory diagram (No. 2) of the recording device according to the embodiment. FIG. 3 is an exploded perspective view showing a schematic configuration of the liquid discharge head according to the embodiment. FIG. 4 is a partially enlarged perspective perspective view of the liquid discharge head shown in FIG. FIG. 5 is an enlarged view of the region A shown in FIG. FIG. 6 is a cross-sectional view taken along the line BB shown in FIG. FIG. 7 is a partially enlarged view of a cross section taken along the line CC shown in FIG. FIG. 8 is a plan view of the water repellent film shown in FIG. 7. FIG. 9 is an explanatory diagram showing an example of wiping processing of the flow path member. FIG. 10 is a partially enlarged cross-sectional view of the flow path member according to the second embodiment. FIG. 11 is a plan view of the water repellent film shown in FIG. FIG. 12 is a partially enlarged cross-sectional view of the flow path member according to the third embodiment. FIG. 13 is a plan view of the water repellent film shown in FIG. FIG. 14 is a partially enlarged cross-sectional view of the flow path member according to the fourth embodiment. FIG. 15 is a plan view of the water repellent film shown in FIG. FIG. 16A is a plan view of a part of the water repellent film according to the first modification. FIG. 16B is a plan view of a part of the water repellent film according to the second modification. FIG. 16C is a plan view of a part of the water repellent film according to the third modification. FIG. 17A is a plan view of a part of the water repellent film according to the fourth modification. FIG. 17B is a plan view of a part of the water repellent film according to the fifth modification.

Hereinafter, embodiments of the liquid discharge head and the recording device disclosed in the present application will be described in detail with reference to the attached drawings. The present invention is not limited to the embodiments shown below.

<Printer configuration>
First, the outline of the printer 1 which is an example of the recording device according to the embodiment will be described with reference to FIGS. 1 and 2. 1 and 2 are explanatory views of the printer 1 according to the embodiment. Specifically, FIG. 1 is a schematic side view of the printer 1, and FIG. 2 is a schematic plan view of the printer 1. The printer 1 according to the embodiment is, for example, a color inkjet printer.

As shown in FIG. 1, the printer 1 includes a paper feed roller 2, a guide roller 3, a coating machine 4, a head case 5, a plurality of transfer rollers 6, a plurality of frames 7, and a plurality of liquid discharge heads. A transfer roller 9, a dryer 10, a transfer roller 11, a sensor unit 12, and a collection roller 13 are provided. The transfer roller 6 is an example of a transfer unit.

Further, the printer 1 includes a paper feed roller 2, a guide roller 3, a coating machine 4, a head case 5, a plurality of transfer rollers 6, a plurality of frames 7, a plurality of liquid discharge heads 8, a transfer roller 9, a dryer 10, and a transfer. A control unit 14 that controls a roller 11, a sensor unit 12, and a collection roller 13 is provided.

The printer 1 records images and characters on the printing paper P by landing droplets on the printing paper P. The printing paper P is an example of a recording medium. The printing paper P is in a state of being wound around the paper feed roller 2 before use. Then, the printer 1 conveys the printing paper P from the paper feed roller 2 to the inside of the head case 5 via the guide roller 3 and the coating machine 4.

The coating machine 4 uniformly applies the coating agent to the printing paper P. As a result, the printing paper P can be surface-treated, so that the print quality of the printer 1 can be improved.

The head case 5 accommodates a plurality of transfer rollers 6, a plurality of frames 7, and a plurality of liquid discharge heads 8. Inside the head case 5, a space isolated from the outside is formed except that a part such as a portion where the printing paper P enters and exits is connected to the outside.

The internal space of the head case 5 is controlled by the control unit 14 at least one of control factors such as temperature, humidity, and atmospheric pressure, if necessary. The transport roller 6 transports the printing paper P in the vicinity of the liquid discharge head 8 inside the head case 5.

The frame 7 is a rectangular flat plate, and is located close to the upper side of the printing paper P conveyed by the transfer roller 6. Further, as shown in FIG. 2, the frame 7 is positioned so that the longitudinal direction is orthogonal to the conveying direction of the printing paper P. A plurality of (for example, four) frames 7 are located inside the head case 5 along the conveying direction of the printing paper P.

Liquid, for example, ink is supplied to the liquid discharge head 8 from a liquid tank (not shown). The liquid discharge head 8 discharges the liquid supplied from the liquid tank.

The control unit 14 controls the liquid discharge head 8 based on data such as an image and characters, and discharges the liquid toward the printing paper P. The distance between the liquid ejection head 8 and the printing paper P is, for example, about 0.5 to 20 mm.

The liquid discharge head 8 is fixed to the frame 7. The liquid discharge head 8 is positioned so that the longitudinal direction is orthogonal to the transport direction of the printing paper P.

That is, the printer 1 according to the embodiment is a so-called line printer in which the liquid discharge head 8 is fixed inside the printer 1. The printer 1 according to the embodiment is not limited to a line printer, and may be a so-called serial printer.

The serial printer alternately performs an operation of recording while moving the liquid discharge head 8 in a direction intersecting the conveying direction of the printing paper P, for example, reciprocating in a direction substantially orthogonal to each other, and conveying the printing paper P. It is a printer of the method to perform.

As shown in FIG. 2, a plurality of (for example, five) liquid discharge heads 8 are fixed to one frame 7. FIG. 2 shows an example in which three liquid discharge heads 8 are located in front of and two liquid discharge heads 8 in the rear in the transport direction of the printing paper P, and the liquid discharge heads 8 are located in the transport direction of the printing paper P. The liquid discharge head 8 is positioned so that the centers do not overlap.

Then, the head group 8A is composed of a plurality of liquid discharge heads 8 located in one frame 7. The four head groups 8A are located along the transport direction of the printing paper P. Ink of the same color is supplied to the liquid ejection head 8 belonging to the same head group 8A. As a result, the printer 1 can print with four colors of ink using the four head groups 8A.

The colors of the ink discharged from each head group 8A are, for example, magenta (M), yellow (Y), cyan (C), and black (K). The control unit 14 can print a color image on the printing paper P by controlling each head group 8A and ejecting inks of a plurality of colors onto the printing paper P.

The coating agent may be discharged from the liquid discharge head 8 onto the printing paper P in order to perform the surface treatment of the printing paper P.

Further, the number of liquid discharge heads 8 included in one head group 8A and the number of head groups 8A mounted on the printer 1 can be appropriately changed according to the printing target and printing conditions. For example, if the color to be printed on the printing paper P is a single color and the printable range is printed by one liquid discharge head 8, the number of the liquid discharge heads 8 mounted on the printer 1 may be one. Good.

The printing paper P printed inside the head case 5 is conveyed to the outside of the head case 5 by the conveying roller 9 and passes through the inside of the dryer 10. The dryer 10 dries the printed printing paper P. The printing paper P dried by the dryer 10 is conveyed by the conveying roller 11 and collected by the collecting roller 13.

In the printer 1, by drying the printing paper P with the dryer 10, it is possible to prevent the collection rollers 13 from adhering the printing papers P that are overlapped and wound up or rubbing the undried liquid. it can.

The sensor unit 12 is composed of a position sensor, a speed sensor, a temperature sensor, and the like. The control unit 14 can determine the state of each unit of the printer 1 based on the information from the sensor unit 12 and control each unit of the printer 1.

In the printer 1 described so far, the case where the printing paper P is used as the printing target (that is, the recording medium) has been shown, but the printing target in the printer 1 is not limited to the printing paper P, and a roll-shaped cloth or the like is printed. May be.

Further, the printer 1 may be mounted on a transport belt and transported instead of directly transporting the printing paper P. By using the transport belt, the printer 1 can print a sheet of paper, a cut cloth, wood, a tile, or the like.

Further, the printer 1 may print a wiring pattern of an electronic device or the like by discharging a liquid containing conductive particles from the liquid discharge head 8. Further, the printer 1 may produce a chemical by discharging a predetermined amount of liquid chemical agent or a liquid containing the chemical agent from the liquid discharge head 8 toward a reaction vessel or the like.

Further, the printer 1 may include a cleaning unit for cleaning the liquid discharge head 8. The cleaning unit cleans the liquid discharge head 8 by, for example, a wiping process or a capping process.

The wiping process is, for example, a process of removing the liquid adhering to the liquid discharge head 8 by wiping the surface of the portion where the liquid is discharged with a flexible wiper. The wiping process will be described later with reference to FIG.

Also, the capping process is performed as follows, for example. First, a cap is put on the portion where the liquid is discharged, for example, the surface 24c (see FIG. 6) of the flow path member 24 (this is called capping). As a result, a substantially sealed space is formed between the surface 24c and the cap.

Next, the liquid is repeatedly discharged in such a closed space. As a result, it is possible to remove liquids and foreign substances having a viscosity higher than the standard state, which are clogged in the first discharge hole 243 (see FIG. 6) and the second discharge hole 246 (see FIG. 6).

<Construction of liquid discharge head>
Next, the configuration of the liquid discharge head 8 according to the embodiment will be described with reference to FIG. FIG. 3 is an exploded perspective view showing a schematic configuration of the liquid discharge head 8 according to the embodiment.

As shown in FIG. 3, the liquid discharge head 8 includes a head main body 20, a reservoir 21, a circuit board 22, and a head cover 23. Further, the head main body 20 includes a flow path member 24, a piezoelectric actuator board 25, a signal transmission unit 26, and a drive IC 27.

The flow path member 24 of the head body 20 has a substantially flat plate shape, and has a first surface 24a which is one main surface and a second surface 24b located on the opposite side of the first surface 24a. The first surface 24a has an opening 241a (see FIG. 4), and a liquid is supplied from the reservoir 21 to the inside of the flow path member 24 via the opening 241a.

A plurality of first ejection holes 243 (see FIG. 4) for ejecting liquid to the printing paper P are located on the second surface 24b. A flow path for flowing a liquid from the first surface 24a to the second surface 24b is formed inside the flow path member 24.

The piezoelectric actuator board 25 is located on the first surface 24a of the flow path member 24. The piezoelectric actuator substrate 25 has a plurality of displacement elements 30 (see FIG. 6). The displacement element 30 is an example of a pressurizing unit. The displacement element 30 is located on the first surface 24a of the flow path member 24. The piezoelectric actuator substrate 25 will be described later with reference to FIG.

Two signal transmission units 26 are electrically connected to the piezoelectric actuator board 25. Each signal transmission unit 26 includes a plurality of drive ICs (Integrated Circuits) 27. In FIG. 3, one of the signal transmission units 26 is not shown for ease of understanding.

The signal transmission unit 26 supplies a signal to each displacement element 30 of the piezoelectric actuator board 25. The signal transmission unit 26 is formed by, for example, an FPC (Flexible Printed Circuit) or the like.

The drive IC 27 is mounted on the signal transmission unit 26. The drive IC 27 controls the drive of each displacement element 30 on the piezoelectric actuator substrate 25.

The head body 20 has a discharge surface for discharging the liquid and an opposite surface located on the opposite side of the discharge surface. In the following, the discharge surface will be described as the surface 24c of the flow path member 24 (see FIG. 6), and the opposite surface will be described as the first surface 24a of the flow path member 24.

The reservoir 21 is located on the opposite surface side of the head body 20 and is in contact with the first surface 24a other than the piezoelectric actuator substrate 25. The reservoir 21 has a flow path inside, and a liquid is supplied from the outside through the opening 21a. The reservoir 21 has a function of supplying a liquid to the flow path member 24 and a function of storing the supplied liquid.

A circuit board 22 is erected on the surface of the reservoir 21 opposite to the head body 20. A plurality of connectors 28 are located at the ends of the circuit board 22 on the reservoir 21 side. Each connector 28 accommodates an end of a signal transduction unit 26.

A power supply connector 29 is located at the end of the circuit board 22 opposite to the reservoir 21. The circuit board 22 distributes the current supplied from the outside through the connector 29 to the connector 28, and supplies the current to the signal transmission unit 26.

The head cover 23 is located on the opposite surface side of the head body 20 and covers the signal transmission unit 26 and the circuit board 22. As a result, the liquid discharge head 8 can seal the signal transmission unit 26 and the circuit board 22.

Further, the head cover 23 has an opening 23a. The connector 29 of the circuit board 22 is inserted so as to be exposed to the outside through the opening 23a.

The drive IC 27 is in contact with the inner side surface of the head cover 23. The drive IC 27 is pressed against, for example, the inner side surface of the head cover 23. As a result, the heat generated by the drive IC 27 can be dissipated (heat radiated) from the contact portion on the side surface of the head cover 23.

The liquid discharge head 8 may further include members other than the members shown in FIG.

<Structure of head body>
Next, the configuration of the head main body 20 according to the embodiment will be described with reference to FIGS. 4 to 6. FIG. 4 is a partially enlarged perspective perspective view of the head body 20 according to the embodiment, and shows a region through which the right region of the diagram is transmitted. FIG. 5 is an enlarged view of the region A shown in FIG. FIG. 6 is a cross-sectional view taken along the line BB shown in FIG.

As shown in FIGS. 4 and 6, the head main body 20 has a flow path member 24 and a piezoelectric actuator board 25. The flow path member 24 has a supply manifold 241, a plurality of pressurizing chambers 242, a plurality of first discharge holes 243, and a plurality of second discharge holes 246. The first discharge hole 243 is an example of the discharge hole.

The plurality of pressurizing chambers 242 are connected to the supply manifold 241. The plurality of first discharge holes 243 are connected to the plurality of pressurizing chambers 242, respectively. The plurality of second discharge holes 246 are connected to the plurality of first discharge holes 243, respectively.

The pressurizing chamber 242 is open to the first surface 24a (see FIG. 6) of the flow path member 24. Further, the first surface 24a of the flow path member 24 has an opening 241a connected to the supply manifold 241. Then, the liquid is supplied from the reservoir 21 (see FIG. 3) to the inside of the flow path member 24 through the opening 241a.

In the example shown in FIG. 4, the head main body 20 has four supply manifolds 241 inside the flow path member 24. The supply manifold 241 has an elongated shape extending along the longitudinal direction of the flow path member 24, and openings 241a of the supply manifold 241 are formed on the first surface 24a of the flow path member 24 at both ends thereof.

A plurality of pressurizing chambers 242 are two-dimensionally expanded and formed in the flow path member 24. The pressurizing chamber 242 is a hollow region having a substantially rhombic planar shape with rounded corners. The pressurizing chamber 242 is open to the first surface 24a of the flow path member 24, and is closed by joining the piezoelectric actuator substrate 25 to the first surface 24a.

The pressurizing chamber 242 constitutes a pressurizing chamber row arranged in the longitudinal direction. The pressurizing chambers 242 in the pressurizing chamber row are arranged in a staggered pattern between two adjacent pressurizing chamber rows. One pressurizing chamber group is composed of two pressurizing chamber rows connected to one supply manifold 241. In the example shown in FIG. 4, the flow path member 24 has four pressure chamber groups.

Further, the relative arrangement of the pressurizing chambers 242 in each pressurizing chamber group is the same, and each pressurizing chamber group is arranged slightly offset in the longitudinal direction. The first discharge hole 243 is arranged at a position of the flow path member 24 so as to avoid the region facing the supply manifold 241. That is, when the flow path member 24 is viewed through from the first surface 24a side, the first discharge hole 243 does not overlap with the supply manifold 241.

Further, in a plan view, the first discharge hole 243 and the second discharge hole 246 are arranged so as to fit in the mounting area of the piezoelectric actuator substrate 25. Such a first discharge hole 243 and a second discharge hole 246 occupy a region having substantially the same size and shape as the piezoelectric actuator substrate 25 as one group.

Then, by displace the displacement element 30 (see FIG. 6), which is the pressurizing portion of the corresponding piezoelectric actuator substrate 25, the droplets are discharged from the second discharge hole 246 communicating with the first discharge hole 243.

The pressurizing chamber 242 and the supply manifold 241 are connected via an individual supply flow path 245 (see FIG. 6). The individual supply flow path 245 contains a squeeze 36 that is narrower than the other parts. Since the squeeze 36 is narrower than the other parts of the individual supply flow path 245, the flow path resistance is high. As described above, when the flow path resistance of the squeeze 36 is high, the pressure generated in the pressurizing chamber 242 is difficult to escape to the supply manifold 241.

As shown in FIG. 6, the flow path member 24 has a plate group 24P. The plate group 24P has a laminated structure in which a plurality of plates are laminated. In the plate group 24P, when the direction from the first surface 24a to the second surface 24b of the flow path member 24 is the first direction D1, the cavity plate 24A, the base plate 24B, and the aperture (squeezing) are arranged in this order from the first surface 24a side. ) Plate 24C, supply plate 24D,

manifold plates

24E, 24F, 24G, cover plate 24H and nozzle plate 24I are located.

A large number of holes are formed in the plate group 24P. The thickness of each plate of the plate group 24P is about 10 μm to 300 μm. As a result, the accuracy of forming the holes to be formed can be increased. The plate group 24P is aligned and laminated so that these holes communicate with each other to form an individual flow path 244 and a supply manifold 241.

Further, the flow path member 24 has a water repellent film 24M located on the second surface 24b of the flow path member 24. The water-repellent film 24M has a second discharge hole 246 that communicates with the first discharge hole 243. The water-repellent film 24M will be described later with reference to FIGS. 7 and 8.

The head body 20 constitutes an individual flow path 244 with the pressurizing chamber 242 on the upper surface of the plate group 24P, the supply manifold 241 on the lower surface side inside the plate group 24P, and the first discharge hole 243 on the lower surface of the plate group 24P. The parts are arranged close to each other at different positions. Further, the second discharge hole 246 is arranged on the lower surface of the flow path member 24. The head main body 20 has a configuration in which the supply manifold 241 and the second discharge hole 246 are connected via the pressurizing chamber 242 and the first discharge hole 243.

The piezoelectric actuator substrate 25 includes piezoelectric

ceramic layers

25a and 25b, a common electrode 31, an individual electrode 32, a connection electrode 33, a dummy connection electrode 34, and a surface electrode 35 (see FIG. 4).

In the piezoelectric actuator substrate 25, the piezoelectric ceramic layer 25a, the common electrode 31, the piezoelectric ceramic layer 25b, and the individual electrodes 32 are laminated in this order.

The piezoelectric

ceramic layers

25a and 25b each have a thickness of about 20 μm. Each of the piezoelectric

ceramic layers

25a and 25b extends so as to straddle the plurality of pressurizing chambers 242. For the piezoelectric

ceramic layers

25a and 25b, a lead zirconate titanate (PZT) -based ceramic material having ferroelectricity can be used.

The common electrode 31 is formed in the region between the piezoelectric ceramic layer 25a and the piezoelectric ceramic layer 25b over substantially the entire surface direction. That is, the common electrode 31 overlaps all the pressurizing chambers 242 in the region facing the piezoelectric actuator substrate 25. The thickness of the common electrode 31 is about 2 μm. For the common electrode 31, for example, a metal material such as an Ag-Pd system can be used.

The individual electrode 32 includes an individual electrode main body 32a and an extraction electrode 32b. The individual electrode body 32a is located on the piezoelectric ceramic layer 25b in a region facing the pressurizing chamber 242. The individual electrode body 32a is one size smaller than the pressurizing chamber 242 and has a shape substantially similar to that of the pressurizing chamber 242.

The extraction electrode 32b is extracted from the individual electrode body 32a. A connection electrode 33 is formed at one end of the extraction electrode 32b, which is drawn out of the region facing the pressurizing chamber 242. For the individual electrode 32, for example, a metal material such as Au can be used.

The connection electrode 33 is located on the extraction electrode 32b, has a thickness of about 15 μm, and is convex. Further, the connection electrode 33 is electrically joined to the electrode provided in the signal transmission unit 26 (see FIG. 3). For the connection electrode 33, for example, silver-palladium containing glass frit can be used.

The dummy connection electrode 34 is located on the piezoelectric ceramic layer 25b so as not to overlap with various electrodes such as the individual electrodes 32. The dummy connection electrode 34 connects the piezoelectric actuator substrate 25 and the signal transmission unit 26 to increase the connection strength.

Further, the dummy connection electrode 34 equalizes the distribution of the contact positions between the piezoelectric actuator substrate 25 and the piezoelectric actuator substrate 25, and stabilizes the electrical connection. The dummy connection electrode 34 may be formed by the same material and the same process as the connection electrode 33.

The surface electrode 35 is formed on the piezoelectric ceramic layer 25b at a position avoiding the individual electrodes 32. The surface electrode 35 is connected to the common electrode 31 via a via hole formed in the piezoelectric ceramic layer 25b. Therefore, the surface electrode 35 is grounded and held at the ground potential. The surface electrode 35 may be formed by the same material and the same process as the individual electrode 32.

The plurality of individual electrodes 32 are individually electrically connected to the control unit 14 (see FIG. 1) via a signal transmission unit 26 and wiring in order to individually control the potential. The piezoelectric ceramic layer 25b sandwiched between the individual electrode 32 and the common electrode 31 has an electric field when the individual electrode 32 and the common electrode 31 have different potentials and an electric field is applied to the piezoelectric ceramic layer 25b in the polarization direction. The applied portion acts as an active portion that is distorted by the piezoelectric effect.

As a result, the individual electrode 32, the piezoelectric ceramic layer 25b, and the common electrode 31 facing the pressurizing chamber 242 function as the displacement element 30. Then, the displacement element 30 is unimorphically deformed to press the pressurizing chamber 242, and the liquid is discharged from the second discharge hole 246.

Here, the driving procedure in this embodiment will be described. First, the individual electrode 32 is set to a higher potential (hereinafter referred to as high potential) than the common electrode 31 in advance. Next, each time there is a discharge request, the individual electrode 32 is once set to the same potential as the common electrode 31 (hereinafter referred to as low potential), and is set to high potential again at a predetermined timing.

As a result, the piezoelectric

ceramic layers

25a and 25b return to their original shapes at the timing when the individual electrodes 32 have low potentials, and the volume of the pressurizing chamber 242 increases from the initial state (the potentials of both electrodes are different).

At this time, a negative pressure is applied to the pressurizing chamber 242, and the liquid is sucked into the pressurizing chamber 242 from the supply manifold 241 side. After that, at the timing when the individual electrodes 32 are raised to a high potential again, the piezoelectric

ceramic layers

25a and 25b are deformed so as to be convex toward the pressure chamber 242 side, and the inside of the pressure chamber 242 is reduced by the volume reduction of the pressure chamber 242. Pressure becomes positive pressure.

As a result, the pressure applied to the liquid inside the pressurizing chamber 242 rises, and droplets are discharged. That is, in order to eject the droplets, a drive signal including a pulse with reference to a high potential is supplied to the individual electrodes 32.

This pulse width may be AL (Acoustic Length), which is the length of time for the pressure wave to propagate from the squeeze 36 to the second discharge hole 246. According to this, when the inside of the pressurizing chamber 242 reverses from the negative pressure state to the positive pressure state, the pressures of both are combined, and the droplet can be discharged with a stronger pressure.

Further, in gradation printing, gradation expression is performed by the number of droplets continuously ejected from the second ejection hole 246, that is, the amount of droplets (volume) adjusted by the number of droplet ejections. Therefore, the droplets are continuously ejected a number of times corresponding to the designated gradation expression from the second ejection hole 246 corresponding to the designated dot region.

In general, when liquid discharge is continuously performed, the interval between the pulses supplied to discharge the droplets may be AL. As a result, the period of the residual pressure wave of the pressure generated when the droplet discharged earlier is discharged and the pressure wave of the pressure generated when the droplet discharged later is discharged coincide with each other. Therefore, the residual pressure wave and the pressure wave are superimposed, and the pressure for ejecting the droplet can be amplified. In this case, the velocity of the droplets ejected later becomes faster, and the landing points of the plurality of droplets become closer.

<Structure of water-repellent film according to the first embodiment>
Next, the configuration of the water-repellent film 24M according to the first embodiment will be described with reference to FIGS. 7 and 8. FIG. 7 is a partially enlarged view of a cross section taken along the line CC shown in FIG. FIG. 8 is a plan view of the water repellent film shown in FIG. 7.

As shown in FIG. 7, the head body 20 has a water-repellent film 24M located on the second surface 24b of the flow path member 24 formed of the surface of the nozzle plate 24I. The water-repellent film 24M has a convex portion 247 protruding in the first direction D1. Here, the convex portion 247 refers to a portion having a water repellent film 24M higher than the thickness t0 of the water repellent film 24M in the region 70 farther from the first discharge hole 243 than the convex portion 247. In the example shown in FIGS. 7 and 8, the portion of the water-repellent film 24M located between the first discharge hole 243 and the outer edge 71 in a plan view is a convex portion 247. The thickness t0 of the region 70 is a value obtained by measuring, for example, a portion of the region 70 located between the adjacent first discharge holes 243 in a plan view using an optical interference type film thickness meter. To say. If the obtained thickness t0 differs for each measurement location, the average value is defined as the thickness t0. When the thickness t0 is different for each measurement point, the thickness is measured at 5 points, and the average thickness of the three values excluding the maximum value and the minimum value is defined as t0. Further, unless otherwise specified, each dimension of the flow path member 24 in the following description is also calculated based on the result of measurement using the optical interference type film thickness meter.

In addition, the convex portion 247 is rounded on the outside and the inside with the top portion 248 as a boundary. Here, the top portion 248 is the highest point in the first direction D1 in the cross section perpendicular to the second surface 24b and passing through the center of the first discharge hole 243.

Further, as shown in FIG. 8, the convex portion 247 has an annular shape in a plan view, and is located around the first discharge hole 243 in a plan view concentrically around the first discharge hole 243. .. The second discharge hole 246 located inside the convex portion 247 is positioned so as to overlap the first discharge hole 243 in a plan view. Therefore, the droplet discharged from the first discharge hole 243 is not interfered by the convex portion 247 or the second discharge hole 246, and lands at a predetermined position.

The water-repellent film 24M is formed, for example, by using a silicone-based film-forming material containing fluorine. Specifically, a water-repellent film 24M having a predetermined thickness is formed on the surface of the nozzle plate 24I, and then the surface of the water-repellent film 24M located outside the region to be the convex portion 247 is masked. It is formed by laminating a water-repellent film 24M on the water film 24M by a predetermined height and further removing the mask. The water-repellent film 24M may be laminated a plurality of times. Further, if necessary, heat treatment or drying treatment may be performed. The position and shape of the convex portion 247 can be appropriately changed by changing the design of the mask and the viscosity of the film-forming material. The method for producing the water-repellent film 24M and the convex portion 247 is not limited to the above, and may be formed by any method.

Here, an example of the wiping process of the flow path member 24 shown in FIGS. 7 and 8 will be described with reference to FIG. 9. FIG. 9 is an explanatory diagram showing an example of the wiping process.

As shown in FIG. 9, in the wiping treatment, the surface 24c of the water-repellent film 24M is wiped by moving the wiper 90 in the second direction D2 along the second surface 24b, and the liquid adhering to the surface 24c. It is a process to remove. The wiper 90 is, for example, an elastic member harder than the water-repellent film 24M. Specifically, a rubber member having a hardness of 30 to 90 can be applied as the wiper 90. Here, the hardness of the wiper 90 can be measured using, for example, a durometer standardized by JIS K6253.

Since the water-repellent film 24M has the convex portion 247, the wiper 90 is less likely to come into contact with the edge portion 73 of the water-repellent film 24M located around the first discharge hole 243 during the wiping process. Therefore, the peeling of the water-repellent film 24M due to the wiping treatment is reduced.

Further, as described above, the convex portion 247 protrudes in the first direction D1. Therefore, in the convex portion 247, even if the water-repellent film 24M is worn by the wiping treatment, the water-repellent film 24M may exist for a long period of time. Therefore, the water repellency of the flow path member 24 can be maintained. Further, since the convex portion 247 is located around the first discharge hole 243, it becomes difficult for foreign matter to enter the first discharge hole 243 during the wiping process.

Further, as described above, the convex portion 247 has a rounded vicinity of the top portion 248. Therefore, excessive wear and damage of the convex portion 247 and the wiper 90 due to the wiping process can be suppressed.

Further, since the convex portion 247 is formed of the water-repellent film 24M, it is compared with a configuration having a convex portion integrated with the nozzle plate 24I made of metal or resin (a configuration in which the nozzle plate 24I itself has a convex portion). Therefore, the load on the wiper 90 can be reduced.

Returning to FIGS. 7 and 8, the configuration of the water-repellent film 24M according to the first embodiment will be further described.

The surface inclination of the convex portion 247 with respect to the second surface 24b may be different between the inner side and the outer side with the top portion 248 interposed therebetween. Specifically, when the convex portion 247 has a region closer to the first discharge hole 243 than the top portion 248 as the first region R1 and a region closer to the first discharge hole 243 than the top portion 248 as the second region R2, The inclination θ1 of the surface of the first region R1 with respect to the second surface 24b may be smaller than the inclination θ2 of the surface of the second region R2 with respect to the second surface 24b. By defining the inclinations θ1 and θ2 in this way, the external force received by the convex portion 247 from the wiper 90 during the wiping process is reduced, so that the durability of the water-repellent film 24M including the convex portion 247 is improved. Here, the inclination θ1 refers to the angle formed by the line segment connecting the top portion 248 and the outer edge 71 and the second surface 24b in FIG. 7. Further, the inclination θ2 refers to the angle formed by the line segment connecting the top portion 248 and the inner edge 72 and the second surface 24b in FIG. 7. The inner edge 72 is a boundary located inside the top portion 248 closer to the first discharge hole 243 than the top portion 248 among the convex portions 247 protruding in the first direction D1.

Further, in the water-repellent film 24M, the top portion 248 of the convex portion 247 may have a height t1 of 1.2 times or more and 1.5 times or less the thickness t0 of the water-repellent film 24M in the region 70. As a result, even if a part of the convex portion 247 is worn due to repeated wiping treatment, for example, the convex portion 247 remains, and the durability of the water-repellent film 24M can be improved. In addition, the amount of liquid droplets discharged can be stabilized without interfering with the discharge of the liquid from the first discharge hole 243. Further, during the wiping treatment, it becomes difficult to contact only the convex portion 237, and the wiping treatment can be performed on the region 70 of the water-repellent film 24M. Here, the thickness t0 can be, for example, about 100 nm. When the height of the top portion 248 is different for each part, the average height can be set to the height t1. Of the total number of tops 248 of the convex portion 247, 60% or more has a height t1 of 1.2 times or more and 1.5 times or less of the thickness t0 of the water-repellent film 24M in the region 70. When present, the amount of droplets of the discharged liquid can be further stabilized.

Further, in the convex portion 247, the distance w1 between the top portions 248 is 4.0 times or more and 6.6 times or less the opening diameter w0 of the first discharge hole 243 in the opposed convex portions facing each other with the first discharge hole 243 in between. There may be. As a result, the durability of the water-repellent film 24M can be improved. In addition, the amount of liquid droplets discharged can be stabilized without interfering with the discharge of the liquid from the first discharge hole 243. Further, water repellency can be ensured between the convex portion 247 and the second discharge hole 246. Here, the opening diameter w0 can be, for example, about 10 to 30 μm.

<Structure of water repellent film according to the second embodiment>
Next, the configuration of the water-repellent film 24M according to the second embodiment will be described with reference to FIGS. 10 and 11. FIG. 10 is a partially enlarged cross-sectional view of the flow path member according to the second embodiment. FIG. 11 is a plan view of the water repellent film shown in FIG.

In the following description, duplicate description may be omitted by assigning the same reference numerals to the same parts as those in the first embodiment.

In the head body 20 according to the second embodiment, the water-repellent film 24M located on the second surface 24b of the flow path member 24 is closer to the first discharge hole 243 than the top 248 from the second region R2 to the first discharge hole. It is also located in the third region R3, which is the region up to the edge of 243. As a result, the water repellency of the second surface 24b can be ensured even in the flow path member 24 located in the third region R3 inside the second region R2.

<Structure of water repellent film according to the third embodiment>
Next, the configuration of the water-repellent film 24M according to the third embodiment will be described with reference to FIGS. 12 and 13. FIG. 12 is a partially enlarged cross-sectional view of the flow path member according to the third embodiment. FIG. 13 is a plan view of the water repellent film shown in FIG.

In the head body 20 according to the third embodiment, the flow path member is such that the inclination θ4 of the surface of the third region R3 with respect to the second surface 24b is smaller than the inclination θ3 of the surface of the second region R2 with respect to the second surface 24b. The water repellent film 24M is located on the second surface 24b of 24. As a result, during the wiping process, the convex portion 247 becomes easily bent inward and outward according to the external force received from the wiper 90, and is easily deformed. Therefore, the durability (wear resistance) of the convex portion 247 is further improved. Here, the inclination θ3 is the angle formed by the line segment connecting the top portion 248 and the inner edge 72 and the second surface 24b in FIG. Further, the inclination θ4 is an angle formed by a line segment connecting the contact portion 75 and the inner edge 72, which are in contact with the first discharge hole 243 and the water repellent film 24M, and the second surface 24b in FIG.

<Structure of water repellent film according to the fourth embodiment>
Next, the configuration of the water-repellent film 24M according to the fourth embodiment will be described with reference to FIGS. 14 and 15. FIG. 14 is a partially enlarged cross-sectional view of the flow path member according to the fourth embodiment. FIG. 15 is a plan view of the water repellent film shown in FIG.

In the head body 20 according to the fourth embodiment, when the region from the second region R2 of the convex portion 247 to the edge of the first discharge hole 243 is the third region R3, the third region R3 is a flat portion 249 on the surface. The water-repellent film 24M is located on the second surface 24b of the flow path member 24 so as to have. As a result, even if foreign matter enters between the convex portion 247 and the second discharge hole 246, it becomes difficult for the foreign matter to enter the first discharge hole 243 from the second discharge hole 246. Here, the flat portion 249 is a plane in which the surface of the water-repellent film 24M in the third region R3 has parallelism within 1 ° with respect to the second surface 24b and is defined by JIS B0021 (1998). A continuous portion having a degree of 1 mm or less.

<Structure of water-repellent film according to modified example>
Next, the configuration of the water-repellent film 24M according to the modified example will be described with reference to FIGS. 16A to 16C. 16A to 16C are plan views of a part of the water repellent film according to the first to third modifications.

As shown in FIG. 16A, the flow path member 24 included in the head body 20 according to the first modification has a water-repellent film according to each embodiment in that the shape of the convex portion 247 in a plan view is not an annular shape but an arc shape. It is different from 24M. Even when such a convex portion 247 is provided, the peeling of the water-repellent film 24M due to the wiping treatment is reduced. In the case of the aspect of FIG. 16A, when the wiper 90 (see FIG. 10) moves in the second direction D2, the contact area between the wiper 90 and the convex portion 247 becomes large, and the peeling of the water repellent film 24M is more effective. Is reduced to.

Further, as shown in FIG. 16B, the convex portions 247 may have opposed

convex portions

247a and 247b facing each other with the first discharge hole 243 in between. Even when such a convex portion 247 is provided, the peeling of the water-repellent film 24M due to the wiping treatment is reduced. In the case of the aspect of FIG. 16B, when the wiper 90 moves in the second direction D2, the contact area between the wiper 90 and the convex portion 247 becomes large, and the peeling of the water repellent film 24M is more effectively reduced.

Further, as shown in FIG. 16C, the convex portions 247 do not necessarily have to face each other with the first discharge hole 243 in between. Even when such a convex portion 247 is provided, the peeling of the water-repellent film 24M due to the wiping treatment is reduced. At this time, if the position of the convex portion 247 with respect to the first discharge hole 243 is adjusted so that the contact area with the convex portion 247 is maximized with respect to the moving direction of the wiper 90 in the wiping process, the water-repellent film 24M is more peeled off. Effectively reduced. Specifically, the wiper 90 may move in the second direction D2.

Further, in each of the above-described embodiments and modifications, the water-repellent film 24M having a substantially circular or arcuate convex portion 247 in a plan view has been described, but the present invention is not limited to this. This point will be described by taking FIGS. 17A and 17B as examples. 17A and 17B are plan views of a part of the water-repellent film according to the fourth and fifth modifications.

As shown in FIG. 17A, the flow path member 24 included in the head body 20 according to the fourth modification is different from the water repellent film 24M according to each embodiment in that the shape of the convex portion 247 in a plan view is elliptical. To do. Further, as shown in FIG. 17B, the flow path member 24 included in the head body 20 according to the fifth modification has a water-repellent film according to each embodiment in that the convex portion 247 in a plan view has a substantially square shape. It is different from 24M. Even when such a convex portion 247 is provided, the peeling of the water-repellent film 24M due to the wiping treatment is reduced.

Although each embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention. For example, in the above-described embodiment, the example in which the plate group 24P of the flow path member 24 is composed of a plurality of laminated plates is shown, but when the plate group 24P is composed of a plurality of laminated plates. Not limited.

For example, the flow path member 24 may be formed by forming the supply manifold 241 and the individual flow path 244 by etching.

Further, the water-repellent film 24M has a curved surface on the surface from the top portion 248 of the convex portion 247 to the edge of the first discharge hole 243, that is, the surface of the second discharge hole 246 (however, the flat portion 249 (see FIG. 14) is excluded). It may be. At this time, when the top portion 248 of the convex portion 247 to the edge of the first discharge hole 243 is viewed in cross section, except for the flat portion 249, it has a curved surface whose surface gradient changes continuously. More specifically, the slope of the surface of the second discharge hole 246 changes continuously, and has a slope-like surface shape that slopes smoothly. As a result, the durability (wear resistance) of the water-repellent film 24M in the second discharge hole 246 located inside the convex portion 247 can be further improved.

As described above, the liquid discharge head 8 according to the embodiment includes a flow path member 24, a pressurizing portion (displacement element 30), and a plurality of discharge holes (first discharge hole 243). The flow path member 24 has a first surface 24a and a second surface 24b located on the opposite side of the first surface 24a. The pressurizing portion (displacement element 30) is located on the first surface 24a. The plurality of discharge holes (first discharge hole 243) are located on the second surface 24b. The flow path member 24 has a water repellent film 24M on the second surface 24b. The water-repellent film 24M has a convex portion 247 protruding in the first direction D1 when the direction from the first surface 24a to the second surface 24b is the first direction D1. The convex portion 247 is located around the discharge hole (first discharge hole 243) in the plan view of the second surface 24b, and has an annular or arc shape in the plan view. Therefore, the load on the wiper 90 can be reduced.

Further, in the liquid discharge head 8, the convex portion 247 has a first region R1 that is farther from the discharge hole (first discharge hole 243) than the top 248 of the convex portion 247, and a discharge hole (first discharge hole) from the top 248. It has a second region R2 close to 243), and the inclination θ1 of the surface of the first region R1 with respect to the second surface 24b may be smaller than the inclination θ2 of the surface of the second region R2 with respect to the second surface 24b. As a result, the load on the wiper 90 can be reduced.

Further, in the liquid discharge head 8 according to the embodiment, the water-repellent film 24M may be located in a region (third region R3) from the second region R2 to the edge of the discharge hole (first discharge hole 243). As a result, the water repellency of the second surface 24b can be ensured even in the flow path member 24 located in the third region R3.

Further, in the liquid discharge head 8 according to the embodiment, the water-repellent film 24M has a second surface 24b when the region from the second region R2 to the edge of the discharge hole (first discharge hole 243) is the third region R3. The inclination θ4 of the surface of the third region R3 with respect to the second surface 24b may be smaller than the inclination θ3 of the surface of the second region R2 with respect to the second surface 24b. As a result, the durability (wear resistance) of the convex portion 247 is improved.

Further, in the liquid discharge head 8 according to the embodiment, the water-repellent film 24M has a third region R3 when the region from the second region R2 to the edge of the discharge hole (first discharge hole 243) is the third region R3. May have a flat portion 249 on its surface. This makes it difficult for foreign matter to enter the first discharge hole 243 from the second discharge hole 246.

Further, in the liquid discharge head 8 according to the embodiment, the water-repellent film 24M has a water-repellent film 24M in a region 70 in which at least one of the convex portions 247 is separated from the discharge hole (first discharge hole 243) by the convex portion 247. It may have a height t1 of 1.2 times or more and 1.5 times or less of the thickness t0 of. Thereby, the durability of the water-repellent film 24M can be improved. In addition, the amount of liquid droplets discharged from the first discharge hole 243 can be stabilized.

Further, in the liquid discharge head 8 according to the embodiment, the water-repellent film 24M has facing convex portions facing each other with the discharge hole (first discharge hole 243) interposed therebetween, and the facing convex portion has a distance w1 between the top portions 248. , The opening diameter w0 of the discharge hole (first discharge hole 243) may be 4.0 times or more and 6.6 times or less. As a result, the amount of liquid droplets discharged from the first discharge hole 243 can be stabilized. Further, water repellency can be ensured between the convex portion 247 and the second discharge hole 246.

Further effects and modifications can be easily derived by those skilled in the art. For this reason, the broader aspects of the invention are not limited to the particular details and representative embodiments expressed and described as described above. Thus, various modifications can be made without departing from the spirit or scope of the general concept of the invention as defined by the appended claims and their equivalents.

1 Printer (an example of recording device)
4 Coating machine 6 Conveying roller (example of conveying part)
8 Liquid discharge head 10 Dryer 14 Control unit 24 Flow path member

24a First surface

24b Second surface 24c Surface 24M Water repellent film 30 Displacement element (example of pressurizing unit)
243 First discharge hole (example of discharge hole)
246 Second discharge hole 247 Convex part 248 Top part 249 Flat part

Claims

A flow path member having a first surface and a second surface located on the opposite side of the first surface,
The pressurizing part located on the first surface and
It is provided with a plurality of discharge holes located on the second surface.
The flow path member
It has a water-repellent film on the second surface,
The water repellent film is
When the direction from the first surface to the second surface is the first direction, it has a convex portion protruding in the first direction.
The convex portion is a liquid discharge head that is located around the discharge hole in the plan view of the second surface and has an annular or arc shape in the plan view.
The convex part is
It has a first region that is farther from the discharge hole than the top of the convex portion and a second region that is closer to the discharge hole than the top.
The liquid discharge head according to claim 1, wherein the inclination of the surface of the first region with respect to the second surface is smaller than the inclination of the surface of the second region with respect to the second surface.
The liquid discharge head according to claim 2, wherein the water-repellent film is also located in a region from the second region to the edge of the discharge hole.
The water-repellent film is formed when the region from the second region to the edge of the discharge hole is defined as the third region.
The liquid discharge head according to claim 3, wherein the inclination of the surface of the third region with respect to the second surface is smaller than the inclination of the surface of the second region with respect to the second surface.
The water-repellent film is formed when the region from the second region to the edge of the discharge hole is defined as the third region.
The liquid discharge head according to claim 3 or 4, wherein the third region has a flat portion on the surface.
The liquid discharge head according to any one of claims 1 to 4, wherein the water-repellent film has a curved surface from the top of the convex portion to the edge of the discharge hole.
At least one of the convex portions of the water-repellent film has a height of 1.2 times or more and 1.5 times or less of the thickness of the water-repellent film in a region farther from the discharge hole than the convex portion. The liquid discharge head according to any one of claims 1 to 6.
The water-repellent film has opposed convex portions facing each other with the discharge hole interposed therebetween.
The liquid discharge head according to any one of claims 1 to 7, wherein the opposed convex portion has a distance between the tops of 4.0 times or more and 6.6 times or less of the opening diameter of the discharge hole.
The liquid discharge head according to any one of claims 1 to 8.
A recording device including a transport unit for transporting a recording medium to the liquid discharge head.
The liquid discharge head according to any one of claims 1 to 8.
A recording device equipped with a coating machine for applying a coating agent to a recording medium.
The liquid discharge head according to any one of claims 1 to 8.
A recording device equipped with a dryer for drying the recording medium.
Further provided with a wiper that wipes the surface of the water-repellent film,
The recording device according to any one of claims 9 to 11, wherein the wiper has a hardness of 30 to 90.