Droplet ejection head and recording apparatus

Abstract

A droplet dispensing head according to an embodiment is provided with a head body, a driver IC, a flexible substrate, and a head substrate. The head body dispenses a droplet. The driver IC controls driving of the head body. The flexible substrate has the driver IC mounted thereon, and is electrically connected to the head body. The head substrate includes a first connector. The flexible substrate includes a second connector corresponding to the first connector, and enables the second connector to be flipped. The second connector is connected to the first connector in a flipped state.

Description

Technical Field

[0001] The disclosed embodiments relate to a droplet ejection head and a recording apparatus.

Background Art

[0002] As printing apparatuses, inkjet printers and inkjet plotters using an inkjet recording method are known. Such an inkjet printing apparatus is equipped with a droplet ejection head for ejecting droplets.

[0003] Such a droplet ejection head is equipped with terminals inserted into connectors on a head substrate, and a flexible substrate such as a COF (Chip on Film, or Chip on Flexible) is mounted, which is electrically connected to the head substrate via these terminals (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in a conventional droplet ejection head, since the head substrate and the flexible substrate are connected only by inserting the terminals of the flexible substrate into the connectors of the head substrate, there is a risk that the terminals of the flexible substrate may fall out from the connectors of the head substrate.

[0006] One aspect of the embodiment has been made in view of the above, and an object thereof is to provide a droplet ejection head and a recording apparatus capable of firmly connecting a head substrate and a flexible substrate.

Means for Solving the Problems

[0007] A droplet discharge head according to one aspect of the embodiment includes a head body, a driver IC, a flexible substrate, and a head substrate. The head body discharges droplets. The driver IC controls the driving of the head body. The flexible substrate has the driver IC mounted thereon and is electrically connected to the head body. The head substrate has a first connector. The flexible substrate has a second connector corresponding to the first connector, and the second connector can be turned over front and back. The second connector is connected to the first connector in a state where it is turned over front and back.

[0008] In addition, a recording apparatus according to one aspect of the embodiment includes the above-described droplet discharge head.

Advantages of the Invention

[0009] According to one aspect of the embodiment, the head substrate and the flexible substrate can be firmly connected.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Figure 14

Figure 15

Embodiments for Carrying Out the Invention

[0011] Hereinafter, with reference to the accompanying drawings, embodiments of the droplet discharge head and the recording apparatus disclosed in the present application will be described in detail. Note that the present invention is not limited to the embodiments shown below.

[0012] As printing apparatuses, inkjet printers and inkjet plotters using an inkjet recording method are known. Such an inkjet printing apparatus is equipped with a droplet discharge head for discharging droplets.

[0013] Such a droplet discharge head is equipped with terminals inserted into the connector of the head substrate, and a flexible substrate such as a COF is mounted which is electrically connected to the head substrate via these terminals.

[0014] However, in a conventional droplet discharge head, since the head substrate and the flexible substrate are connected only by inserting the terminals of the flexible substrate into the connector of the head substrate, there is a risk that the terminals of the flexible substrate may fall out of the connector of the head substrate.

[0015] Therefore, in view of the above problems, the realization of a droplet discharge head and a recording apparatus capable of firmly connecting a head substrate and a flexible substrate is expected.

[0016] <Configuration of Printer> First, an outline of a printer 1, which is an example of a recording apparatus according to an embodiment, will be described with reference to FIGS. 1 and 2. FIGS. 1 and 2 are explanatory views of the printer 1 according to the embodiment.

[0017] 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.

[0018] As shown in FIG. 1, the printer 1 includes a paper feed roller 2, a guide roller 3, an applicator 4, a head case 5, a plurality of transport rollers 6, a plurality of frames 7, a plurality of droplet discharge heads 8, a transport roller 9, a dryer 10, a transport roller 11, a sensor unit 12, and a recovery roller 13. The transport roller 6 is an example of a transport unit.

[0019] Furthermore, the printer 1 has a control unit 14 that controls the paper feed roller 2, the guide roller 3, the applicator 4, the head case 5, the plurality of transport rollers 6, the plurality of frames 7, the plurality of droplet discharge heads 8, the transport roller 9, the dryer 10, the transport roller 11, the sensor unit 12, and the recovery roller 13.

[0020] The printer 1 records an image or 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 transports 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 applicator 4.

[0021] The coater 4 uniformly applies the coating agent to the printing paper P. As a result, since the surface treatment can be performed on the printing paper P, the printing quality of the printer 1 can be improved.

[0022] The head case 5 houses a plurality of conveying rollers 6, a plurality of frames 7, and a plurality of droplet ejection heads 8. Inside the head case 5, except for a part such as the portion where the printing paper P enters and exits, which is connected to the outside, a space isolated from the outside is formed.

[0023] The internal space of the head case 5 is controlled by the control unit 14 for at least one of the control factors such as temperature, humidity, and air pressure as necessary. The conveying roller 6 conveys the printing paper P inside the head case 5 to the vicinity of the droplet ejection head 8.

[0024] The frame 7 is a rectangular flat plate and is positioned close to the upper side of the printing paper P conveyed by the conveying roller 6. Also, as shown in FIG. 2, the frame 7 is positioned such that its longitudinal direction is orthogonal to the conveying direction of the printing paper P. And inside the head case 5, a plurality (for example, four) of frames 7 are positioned along the conveying direction of the printing paper P.

[0025] In the following description, the conveying direction of the printing paper P is also referred to as the "sub-scanning direction". Also, in the following description, the direction orthogonal to this sub-scanning direction and parallel to the printing paper P is also referred to as the "main scanning direction".

[0026] Liquid, for example, ink, is supplied to the droplet ejection head 8 from a liquid tank (not shown). The droplet ejection head 8 ejects the droplets supplied from the liquid tank.

[0027] The control unit 14 controls the droplet ejection head 8 based on data such as images and characters, and ejects droplets toward the printing paper P. The distance between the droplet ejection head 8 and the printing paper P is, for example, about 0.5 to 20 mm.

[0028] The droplet ejection head 8 is fixed to the frame 7. The droplet ejection head 8 is fixed to the frame 7, for example, at both longitudinal ends. The droplet ejection head 8 is positioned such that its longitudinal direction is orthogonal to the conveyance direction of the printing paper P.

[0029] That is, the printer 1 according to the embodiment is a so-called line printer in which the droplet ejection head 8 is fixed inside the printer 1. Note that the printer 1 according to the embodiment is not limited to a line printer and may be a so-called serial printer.

[0030] This serial printer is a printer that alternately performs an operation of recording while moving the droplet ejection head 8 in a direction intersecting the conveyance direction of the printing paper P, for example, in a substantially orthogonal direction, and the conveyance of the printing paper P.

[0031] As shown in FIG. 2, a plurality (for example, five) of droplet ejection heads 8 are fixed to one frame 7. Note that FIG. 2 shows an example in which three droplet ejection heads 8 are positioned in front of the conveyance direction of the printing paper P and two droplet ejection heads 8 are positioned behind. In FIG. 2, the droplet ejection heads 8 are positioned such that the centers of the respective droplet ejection heads 8 do not overlap in the conveyance direction of the printing paper P.

[0032] And a head group 8A is constituted by a plurality of droplet ejection heads 8 positioned on one frame 7. The four head groups 8A are positioned along the conveyance direction of the printing paper P. The same color ink is supplied to the droplet ejection heads 8 belonging to the same head group 8A. Thereby, the printer 1 can perform printing with four-color ink using the four head groups 8A.

[0033] The colors of the ink ejected 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 to eject a plurality of colors of ink onto the printing paper P.

[0034] In addition, in order to perform surface treatment on the printing paper P, a coating agent may be discharged from the droplet discharge head 8 onto the printing paper P.

[0035] Further, at least one of the number of droplet 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 at least one of the object to be printed and the printing conditions. For example, if the color to be printed on the printing paper P is single-color and the range printable by one droplet discharge head 8 is printed, the number of droplet discharge heads 8 mounted on the printer 1 may be one.

[0036] The printing paper P that has undergone printing processing inside the head case 5 is conveyed outside 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.

[0037] In the printer 1, by drying the printing paper P with the dryer 10, the suppression effect of preventing the printed printing papers P from adhering to each other and being wound up overlapping or the undried droplets from being rubbed at the collecting roller 13 is improved.

[0038] The sensor unit 12 is composed of at least one of a position sensor, a speed sensor, a temperature sensor, etc. The control unit 14 can judge the states of each part of the printer 1 based on the information from such a sensor unit 12 and control each part of the printer 1.

[0039] In the printer 1 described so far, the case where the printing paper P is used as the printing object (that is, the recording medium) has been shown, but the printing object in the printer 1 is not limited to the printing paper P, and a roll-shaped cloth or the like may be used as the printing object.

[0040] Further, instead of directly transporting the printing paper P, the printer 1 may place it on a transport belt and transport it. By using the transport belt, the printer 1 can print on single sheets, cut cloth, wood, tiles, etc.

[0041] Also, the printer 1 may discharge droplets containing conductive particles from the droplet discharge head 8 to print wiring patterns of electronic devices, etc. Further, the printer 1 may discharge a predetermined amount of liquid chemical agent or droplets containing the chemical agent from the droplet discharge head 8 toward a reaction vessel, etc., to produce chemicals.

[0042] Also, the printer 1 may be provided with a cleaning unit for cleaning the droplet discharge head 8. The cleaning unit performs cleaning of the droplet discharge head 8 by, for example, wiping processing or capping processing.

[0043] The wiping processing is, for example, a process of removing the liquid adhering to the second surface 21b (see FIG. 6) by wiping the surface of the portion where droplets are discharged, for example, the second surface 21b of the flow path member 21 (see FIG. 3), with a flexible wiper.

[0044] Also, the capping processing is performed, for example, as follows. First, a cap is placed so as to cover the portion where droplets are discharged, for example, the second surface 21b of the flow path member 21 (this is called capping). Thereby, a substantially sealed space is formed between the second surface 21b and the cap.

[0045] Next, droplet discharge is repeated in such a sealed space. Thereby, it is possible to remove the liquid having a higher viscosity than the standard state and foreign substances that have clogged the discharge holes 63 (see FIG. 4).

[0046] <Configuration of Droplet Discharge Head> Next, the configuration of the droplet discharge head 8 according to the embodiment will be described with reference to FIG. 3. FIG. 3 is an exploded perspective view showing the schematic configuration of the droplet discharge head 8 according to the embodiment. In FIG. 3, the wiring portion 30 including the flexible substrate 31 is shown schematically in particular. The detailed configuration of the flexible substrate 31 according to the present embodiment will be shown in FIGS. 7 to 15.

[0047] The droplet discharge head 8 includes a head body 20, a wiring portion 30, a housing 40, and a pair of heat dissipation plates 50. The head body 20 has a flow path member 21, a piezoelectric actuator substrate 22 (see FIG. 4), and a reservoir 23.

[0048] In the following description, for convenience, the direction in which the head body 20 is provided in the droplet discharge head 8 is also referred to as "down". Also, in the following description, for convenience, the direction in which the housing 40 is provided with respect to the head body 20 is also referred to as "up".

[0049] The flow path member 21 of the head body 20 has a substantially flat plate shape and has a first surface 21a (see FIG. 6) which is one main surface and a second surface 21b (see FIG. 6) located on the opposite side of the first surface 21a. The first surface 21a has an opening 61a (see FIG. 4), and liquid is supplied from the reservoir 23 into the flow path member 21 through the opening 61a.

[0050] A plurality of discharge holes 63 (see FIG. 4) for discharging droplets onto the printing paper P are located on the second surface 21b. And a flow path for flowing liquid from the first surface 21a to the second surface 21b is formed inside the flow path member 21. The configuration of the flow path member 21 will be described later with reference to FIGS. 4 to 6.

[0051] The piezoelectric actuator substrate 22 is located on the first surface 21a of the flow path member 21. The piezoelectric actuator substrate 22 has a plurality of displacement elements 70 (see FIG. 5). Also, the flexible substrate 31 of the wiring portion 30 is electrically connected to the piezoelectric actuator substrate 22. The configuration of the piezoelectric actuator substrate 22 will be described later with reference to FIGS. 4 to 6.

[0052] A reservoir 23 is disposed on the piezoelectric actuator substrate 22. Openings 23a are provided at both ends in the main scanning direction of the reservoir 23. The reservoir 23 has a flow path inside, and liquid is supplied from the outside through the openings 23a. The reservoir 23 has a function of supplying liquid to the flow path member 21 and a function of storing the supplied liquid.

[0053] The wiring unit 30 includes a flexible substrate 31, a head substrate 32, a driver IC (Integrated Circuit) 33, a pressing member 34, and an elastic member 35. The flexible substrate 31 has a function of transmitting a predetermined signal sent from the outside to the head body 20. As shown in FIG. 3, the droplet discharge head 8 according to the embodiment has two flexible substrates 31.

[0054] The first end of the flexible substrate 31 is electrically connected to the piezoelectric actuator substrate 22 of the head body 20. The second end opposite to the first end of the flexible substrate 31 is drawn upward so as to pass through the opening 23b of the reservoir 23 and is electrically connected to the head substrate 32.

[0055] Thereby, the piezoelectric actuator substrate 22 of the head body 20 and the outside can be electrically connected. The flexible substrate 31 is, for example, a film-shaped substrate (COF) made of polyimide, and a driver IC 33 and the like are mounted on the substrate. The detailed configuration of the flexible substrate 31 will be described later with reference to FIGS. 7 to 15.

[0056] The head substrate 32 is located above the head body 20. The head substrate 32 has a function of distributing signals to the driver IC 33. A connector (hereinafter referred to as the first connector) 32a (see FIG. 9) for connecting a flexible substrate is mounted on the head substrate 32.

[0057] The driver IC 33 is provided on one surface of the flexible substrate 31. As shown in FIG. 3, in the droplet discharge head 8 according to the embodiment, two driver ICs 33 are provided on one flexible substrate 31. Note that, in the embodiment, the number of driver ICs 33 provided on one flexible substrate 31 is not limited to two.

[0058] Based on the signal sent from the control unit 14 (see FIG. 1), the driver IC 33 drives the piezoelectric actuator substrate 22 of the head body 20. Thereby, the driver IC 33 drives the droplet discharge head 8.

[0059] The pressing member 34 has a substantially U-shaped cross section and presses the driver IC 33 on the flexible substrate 31 from the inside toward the heat sink 50.

[0060] The elastic member 35 is positioned so as to contact the outer wall of a pressing portion (not shown) of the pressing member 34. By providing such an elastic member 35, when the pressing member 34 presses the driver IC 33, the possibility that the pressing member 34 damages the flexible substrate 31 can be reduced.

[0061] The elastic member 35 is formed of, for example, a foam double-sided tape or the like. Further, by using, for example, a non-silicon-based heat conductive sheet as the elastic member 35, the heat dissipation property of the driver IC 33 can be improved. Note that the elastic member 35 does not necessarily have to be provided.

[0062] The housing 40 is disposed on the head body 20 so as to cover the wiring portion 30. Thereby, the housing 40 can seal the wiring portion 30. The housing 40 is formed of, for example, resin or metal.

[0063] The housing 40 has a box shape that extends long in the main scanning direction and has a first opening 40a and a second opening 40b on the side surfaces facing the sub-scanning direction. Such first opening 40a and second opening 40b are an example of openings. Further, the housing 40 has a third opening 40c on the lower surface and a fourth opening 40d on the upper surface.

[0064] One of the pair of heat dissipation plates 50 is arranged to close the first opening 40a in the first opening 40a. The other of the pair of heat dissipation plates 50 is arranged to close the second opening 40b in the second opening 40b.

[0065] The heat dissipation plate 50 is provided to extend in the main scanning direction and is composed of a highly heat dissipative metal, alloy, or the like. The heat dissipation plate 50 is provided to be in contact with the driver IC 33 and has a function of dissipating the heat generated by the driver IC 33.

[0066] The pair of heat dissipation plates 50 are respectively fixed to the housing 40 by screws (not shown). Therefore, the housing 40 to which the heat dissipation plates 50 are fixed has a box shape with the first opening 40a and the second opening 40b closed and the third opening 40c and the fourth opening 40d open.

[0067] The third opening 40c is provided to face the reservoir 23. A flexible substrate 31 and a pressing member 34 are inserted through the third opening 40c.

[0068] The fourth opening 40d is provided for inserting a connector (not shown) provided on the head substrate 32. The space between the connector and the fourth opening 40d may be sealed with resin or the like. This improves the effect of suppressing the intrusion of liquid, dust, or the like into the interior of the housing 40.

[0069] Further, the housing 40 has a heat insulation portion 40e. The heat insulation portion 40e is arranged adjacent to the first opening 40a and the second opening 40b and is provided to protrude outward from the side surface of the housing 40 facing the sub-scanning direction.

[0070] Further, the heat insulating portion 40e is formed so as to extend in the main scanning direction. That is, the heat insulating portion 40e is located between the heat radiating plate 50 and the head body 20. By providing the heat insulating portion 40e in the housing 40 in this way, the inhibitory effect of suppressing the heat generated by the driver IC 33 from being transmitted to the head body 20 via the heat radiating plate 50 is improved.

[0071] Note that the droplet ejection head 8 may further include members other than the members shown in FIG. 3.

[0072] <Configuration of the head body> Next, the configuration of the head body 20 according to the embodiment will be described with reference to FIGS. 4 to 6. FIG. 4 is an enlarged plan view of the head body 20 according to the embodiment. FIG. 5 is an enlarged view of the region surrounded by the alternate long and short dash line shown in FIG. 4. FIG. 6 is a cross-sectional view taken along line A-A shown in FIG. 4.

[0073] As shown in FIG. 4, the head body 20 has a flow path member 21 and a piezoelectric actuator substrate 22. The flow path member 21 has a supply manifold 61, a plurality of pressure chambers 62, and a plurality of discharge holes 63.

[0074] The plurality of pressure chambers 62 are connected to the supply manifold 61. The plurality of discharge holes 63 are respectively connected to the plurality of pressure chambers 62.

[0075] The pressure chamber 62 opens to the first surface 21a (see FIG. 6) of the flow path member 21. The first surface 21a of the flow path member 21 has an opening 61a that is connected to the supply manifold 61. Then, the liquid is supplied into the flow path member 21 from the reservoir 23 (see FIG. 2) through the opening 61a.

[0076] In the example of FIG. 4, four supply manifolds 61 are located inside the flow path member 21 of the head body 20. The supply manifold 61 has an elongated shape extending along the longitudinal direction (i.e., the main scanning direction) of the flow path member 21, and openings 61a of the supply manifold 61 are formed on the first surface 21a of the flow path member 21 at both ends thereof.

[0077] In the flow path member 21, a plurality of pressure chambers 62 are formed to extend two-dimensionally. As shown in FIG. 5, the pressure chamber 62 is a hollow region having a substantially rhombic planar shape with rounded corners. The pressure chamber 62 opens to the first surface 21a of the flow path member 21 and is closed by bonding the piezoelectric actuator substrate 22 to the first surface 21a.

[0078] The pressure chambers 62 constitute pressure chamber rows arranged in the longitudinal direction. The pressure chambers 62 in the pressure chamber rows are arranged in a staggered manner between two adjacent pressure chamber rows. And, one pressure chamber group is constituted by four pressure chamber rows connected to one supply manifold 61. In the example of FIG. 4, the flow path member 21 has four such pressure chamber groups.

[0079] Also, the relative arrangement of the pressure chambers 62 within each pressure chamber group is the same, and each pressure chamber group is arranged with a slight shift in the longitudinal direction.

[0080] The discharge holes 63 are arranged at positions avoiding the region of the flow path member 21 facing the supply manifold 61. That is, when the flow path member 21 is viewed through from the first surface 21a side, the discharge holes 63 do not overlap with the supply manifold 61.

[0081] Furthermore, in a plan view, the discharge holes 63 are arranged so as to be within the mounting region of the piezoelectric actuator substrate 22. Such discharge holes 63 occupy a region having substantially the same size and shape as the piezoelectric actuator substrate 22 as one group.

[0082] Then, by displacing the displacement element 70 (see FIG. 6) of the corresponding piezoelectric actuator substrate 22, droplets are discharged from the discharge holes 63.

[0083] As shown in FIG. 6, the flow path member 21 has a laminated structure in which a plurality of plates are laminated. These plates are, in order from the upper surface of the flow path member 21, a cavity plate 21A, a base plate 21B, an aperture (squeeze) plate 21C, a supply plate 21D, manifold plates 21E, 21F, 21G, a cover plate 21H, and a nozzle plate 21I.

[0084] A large number of holes are formed in the plates. The thickness of the plates is about 10 μm to 300 μm. Thereby, the formation accuracy of the holes can be increased. The plates are laminated with alignment so that these holes communicate with each other to form a predetermined flow path.

[0085] In the flow path member 21, the supply manifold 61 and the discharge hole 63 are connected by an individual flow path 64. The supply manifold 61 is located on the second surface 21b side inside the flow path member 21. The discharge hole 63 is located on the second surface 21b of the flow path member 21.

[0086] The individual flow path 64 has a pressure chamber 62 and an individual supply flow path 65. The pressure chamber 62 is located on the first surface 21a of the flow path member 21. The individual supply flow path 65 is a flow path that connects the supply manifold 61 and the pressure chamber 62.

[0087] Further, the individual supply flow path 65 includes a squeeze 66 that is narrower than other portions. Since the squeeze 66 is narrower than other portions of the individual supply flow path 65, the flow path resistance is high. Thus, when the flow path resistance of the squeeze 66 is high, the pressure generated in the pressure chamber 62 is difficult to escape to the supply manifold 61.

[0088] The piezoelectric actuator substrate 22 has piezoelectric ceramic layers 22A, 22B, a common electrode 71, individual electrodes 72, connection electrodes 73, dummy connection electrodes 74, and a surface electrode 75 (see FIG. 4).

[0089] In the piezoelectric actuator substrate 22, a piezoelectric ceramic layer 22A, a common electrode 71, a piezoelectric ceramic layer 22B, and an individual electrode 72 are laminated in this order.

[0090] Both the piezoelectric ceramic layers 22A and 22B extend on the first surface 21a of the flow path member 21 so as to straddle a plurality of pressure chambers 62. The piezoelectric ceramic layers 22A and 22B each have a thickness of about 20 μm. The piezoelectric ceramic layers 22A and 22B are made of, for example, a lead zirconate titanate (PZT)-based ceramic material having ferroelectricity.

[0091] The common electrode 71 is formed over substantially the entire surface in the plane direction in the region between the piezoelectric ceramic layer 22A and the piezoelectric ceramic layer 22B. That is, the common electrode 71 overlaps all the pressure chambers 62 within the region facing the piezoelectric actuator substrate 22.

[0092] The thickness of the common electrode 71 is about 2 μm. The common electrode 71 is made of, for example, a metal material such as an Ag-Pd system.

[0093] The individual electrode 72 includes a main body electrode 72a and a lead-out electrode 72b. The main body electrode 72a is located in the region on the piezoelectric ceramic layer 22B that faces the pressure chamber 62. The main body electrode 72a is slightly smaller than the pressure chamber 62 and has a shape substantially similar to the pressure chamber 62.

[0094] The lead-out electrode 72b is drawn out from the main body electrode 72a to the outside of the region facing the pressure chamber 62. The individual electrode 72 is made of, for example, a metal material such as an Au system.

[0095] The connection electrode 73 is located on the lead-out electrode 72b, is formed in a convex shape with a thickness of about 15 μm, and is electrically connected to an electrode provided on the flexible substrate 31 (see FIG. 3). The connection electrode 73 is made of, for example, silver-palladium containing glass frit.

[0096] The dummy connection electrode 74 is located on the piezoelectric ceramic layer 22B and is positioned so as not to overlap various electrodes such as the individual electrode 72. The dummy connection electrode 74 connects the piezoelectric actuator substrate 22 and the flexible substrate 31, enhancing the connection strength.

[0097] Also, the dummy connection electrode 74 equalizes the distribution of the contact positions between the piezoelectric actuator substrate 22 and stabilizes the electrical connection. The dummy connection electrode 74 is preferably composed of the same material as the connection electrode 73 and is preferably formed in the same process as the connection electrode 73.

[0098] The surface electrode 75 shown in FIG. 4 is formed on the piezoelectric ceramic layer 22B at a position avoiding the individual electrode 72. The surface electrode 75 is connected to the common electrode 71 through a via hole formed in the piezoelectric ceramic layer 22B.

[0099] As a result, the surface electrode 75 is grounded and held at the ground potential. The surface electrode 75 is preferably composed of the same material as the individual electrode 72 and is preferably formed in the same process as the individual electrode 72.

[0100] The plurality of individual electrodes 72 are each electrically connected to the control unit 14 (see FIG. 1) individually through the flexible substrate 31 and wiring in order to control the potential individually. Then, when the individual electrode 72 and the common electrode 71 are set to different potentials and an electric field is applied in the polarization direction of the piezoelectric ceramic layer 22A, the portion in the piezoelectric ceramic layer 22A where the electric field is applied operates as an active part that is distorted by the piezoelectric effect.

[0101] That is, in the piezoelectric actuator substrate 22, the portions of the individual electrode 72, the piezoelectric ceramic layer 22A, and the common electrode 71 that face the pressure chamber 62 function as the displacement element 70.

[0102] When such a displacement element 70 undergoes unimorph deformation, the pressure chamber 62 is pressed and droplets are ejected from the ejection hole 63.

[0103] Here, the driving procedure of the droplet ejection head 8 according to the embodiment will be described. In advance, the individual electrode 72 is set to a potential higher than that of the common electrode 71 (hereinafter referred to as a high potential). Then, every time there is a ejection request, the individual electrode 72 is temporarily set to the same potential as the common electrode 71 (hereinafter referred to as a low potential), and then, at a predetermined timing, it is set to the high potential again.

[0104] Thereby, at the timing when the individual electrode 72 becomes the low potential, the piezoelectric ceramic layers 22A and 22B return to their original shapes, and the volume of the pressurizing chamber 62 increases compared to the initial state, that is, the state of the high potential. At this time, since a negative pressure is applied to the inside of the pressurizing chamber 62, the liquid in the supply manifold 61 is sucked into the pressurizing chamber 62.

[0105] After that, at the timing when the individual electrode 72 is set to the high potential again, the piezoelectric ceramic layers 22A and 22B are deformed so as to protrude toward the pressurizing chamber 62. That is, as the volume of the pressurizing chamber 62 decreases, the pressure inside the pressurizing chamber 62 becomes a positive pressure. Thereby, the pressure of the liquid in the pressurizing chamber 62 rises, and droplets are ejected from the ejection holes 63.

[0106] That is, in order to eject droplets from the ejection holes 63, the control unit 14 supplies a driving signal including a pulse based on the high potential to the individual electrode 72 using the driver IC 33. This pulse width may be set to AL (Acoustic Length), which is the length of time for the pressure wave to propagate from the squeezing portion 66 to the ejection holes 63.

[0107] Thereby, when the inside of the pressurizing chamber 62 is inverted from the negative pressure state to the positive pressure state, the pressures of both are combined, and droplets can be ejected with a stronger pressure.

[0108] In addition, in halftone printing, halftone representation is performed by adjusting the number of droplets continuously ejected from the ejection holes 63, that is, the amount (volume) of droplets adjusted by the number of droplet ejections. Therefore, the droplets are continuously ejected from the ejection holes 63 corresponding to the specified dot regions for the number of times corresponding to the specified halftone representation.

[0109] Generally, when continuously performing droplet ejection, the interval between pulses supplied to eject droplets may be set as AL. As a result, the period of the residual pressure wave of the pressure generated when ejecting the previously ejected droplet matches the period of the pressure wave of the pressure generated when ejecting the later ejected droplet.

[0110] Therefore, the residual pressure wave and the pressure wave can be superimposed to amplify the pressure for ejecting droplets. In this case, the speed of the later ejected droplets increases, and the landing points of the plurality of droplets become closer.

[0111] <Configuration of Flexible Substrate> Next, the configuration of the flexible substrate 31 according to the embodiment will be described with reference to FIGS. 7 to 15. FIGS. 7 and 8 are explanatory views of the structure of the flexible substrate 31 according to the embodiment and the periphery of the flexible substrate 31.

[0112] Note that FIG. 7 shows a state in which the portion B1 on the flexible substrate 31 where the second connector 31a described later is mounted is not turned inside out. FIG. 8 shows a state in which one of the portions B1 (the portion B1 surrounded by a dashed-dotted line in the figure) is turned inside out. Also, in FIGS. 7 and 8, descriptions of wiring patterns 85 (see FIG. 10) formed in the flexible substrate 31 are omitted.

[0113] As shown in FIGS. 7 and 8, the flexible substrate 31 has a shape that gradually bifurcates and tapers upward. That is, the flexible substrate 31 has two upper portions protruding upward. The lower portion of the flexible substrate 31 is electrically connected to the piezoelectric actuator substrate 22 (see FIG. 4) of the head body 20 (see FIG. 3).

[0114] In addition, a second connector 31a is mounted on the upper portion of the flexible substrate 31. The second connector 31a is connected to the first connector 32a (see FIG. 9) mounted on the head substrate 32 (see FIG. 9), and can electrically connect the flexible substrate 31 and the head substrate 32.

[0115] The flexible substrate 31 enables the second connector 31a to be turned over front and back. The flexible substrate 31 is formed such that the portion B1 can be turned over front and back. When connecting the second connector 31a and the first connector 32a, as shown in FIG. 8, the portion B1 is turned over front and back and then connected to the first connector 32a (see FIG. 9).

[0116] The portion B1 is separated from the other portion B2 (hereinafter referred to as the "other portion") of the flexible substrate 31 where the second connector 31a is not mounted, with a part remaining, by a slit portion 81 (see FIG. 11) described later.

[0117] In the present embodiment, the upper edge portion 311 of the portion B1 is connected to the other portion B2, and the pair of side edge portions 312 and the lower edge portion 313 are separated from the other portion B2. For this reason, in the connection state with the first connector 32a, the portion B1 is turned over front and back and also turned upside down with the upper edge portion 311 as a fulcrum.

[0118] The second connector 31a is connected to the first connector 32a by fitting with the first connector 32a (receptacle). That is, the second connector 31a and the first connector 32a are connected in a so-called BtoB (Board to Board) manner. In this way, by connecting the flexible substrate 31 and the head substrate 32 in a BtoB manner, the flexible substrate 31 and the head substrate 32 can be firmly connected.

[0119] Next, the connection of the flexible substrate 31 will be described with reference to FIGS. 9 and 10. FIG. 9 is a schematic cross-sectional view showing the connection of the flexible substrate 31. FIG. 10 is a schematic cross-sectional view showing another example of the connection of the flexible substrate 31. Note that both FIGS. 9 and 10 show a cross-section of the flexible substrate 31 cut at approximately the center in its width direction.

[0120] As shown in FIG. 9, in the flexible substrate 31, the second connector 31a and the first connector 32a are connected in a state where the portion B1 is turned outward and reversed front and back toward the head substrate 32. In other words, another portion B2 adjacent to the portion B1 has a protruding shape facing outward in a side view. In this way, by inverting the second connector 31a front and back, the second connector 31a can reach farther.

[0121] Also, as shown in FIG. 10, the flexible substrate 31 may be connected in a state where the portion B1 is turned inward and reversed front and back toward the head substrate 32. In other words, another portion B2 adjacent to the portion B1 has a protruding shape facing inward in a side view. Even if the second connector 31a is turned inward and reversed front and back toward the first connector 32a, the second connector 31a can reach farther. In addition, since the portion B1 can be connected in either the outward or inward front-back inversion state, it can be selectively used according to the arrangement of the first connector 32a.

[0122] Next, with reference to FIGS. 11 and 12, the flexible substrate 31 will be further described. FIG. 11 is an explanatory diagram of the front surface 314 of the flexible substrate 31. FIG. 12 is an explanatory diagram of the back surface 315 of the flexible substrate 31. Hereinafter, in the flexible substrate 31, the surface on which the second connector 31a is mounted is referred to as the "front surface (314)", and the opposite surface (back surface) is referred to as the "back surface (315)".

[0123] As shown in FIGS. 11 and 12, the flexible substrate 31 further includes a slit portion 81, a rounded portion 82, a reinforcing plate 83, and a tab 84. The slit portion 81 forms a gap with a predetermined width and is formed so as to surround the portion B1.

[0124] The slit portion 81 is formed in a U shape when viewed facing the flexible substrate 31. Specifically, the portion B1 is substantially rectangular in plan view. As described above, the upper edge portion 311 of the portion B1 is connected to another portion B2, and the pair of side edge portions 312 and the lower edge portion 313 are separated from the other portion B2. The slit portion 81 extends along the pair of side edge portions 312 and the lower edge portion 313 of the portion B1. Thereby, the slit portion 81 forms a U shape.

[0125] In this way, since the portion B1 is separated from the other portion B2 while leaving a part by the slit portion 81, the portion B1 is not restricted. Note that the "U shape" is a shape formed by two parallel straight lines and one straight line connecting the opposing ends of the two straight lines.

[0126] Further, since the slit portion 81 is in a U shape, the movable range of the portion B1 is substantially restricted in the thickness direction of the flexible substrate 31. In this way, since the movable range of the portion B1 is restricted in one direction, the effect of suppressing the displacement of the connection position between the second connector 31a and the first connector 32a (see FIG. 9) can be improved.

[0127] The rounded portion 82 is formed at the base end portion of the slit portion 81, which is the boundary between the portion B1 and the other portion B2. In this way, by forming the rounded portion 82 at the base end portion of the slit portion 81, the stress concentration at the base end portion of the slit portion 81 can be reduced. In this embodiment, the rounded portion 82 is formed in a circular hole shape larger than the width of the slit portion 81, but other shapes may be used, for example, it may be formed in a semicircular shape.

[0128] As shown in FIG. 12, the reinforcing plate 83 is provided on the back surface 315 of the flexible substrate 31. The reinforcing plate 83 is provided so as to cover the portion B1 on the back surface side (the back surface 315 of the flexible substrate 31) of the portion B1, thereby reinforcing the second connector 31a. In this way, by reinforcing the second connector 31a with the reinforcing plate 83, it is possible to improve the effect of suppressing damage to the second connector 31a when attaching and detaching to the first connector 32a (see FIG. 9).

[0129] The reinforcing plate 83 is made of, for example, a hard plastic and is formed in a rectangular shape. The reinforcing plate 83 is transparent or translucent. The reinforcing plate 83 is chamfered at the corners located at least at the base ends of the slit portions 81 among its four corners. Thereby, the effect of suppressing interference with the rounded portions 82 can be improved.

[0130] Also, as shown in FIGS. 11 and 12, a pair of side edge portions 831 of the reinforcing plate 83 protrude from the portion B1 to the inside of the slit portion 81. In other words, a pair of side edge portions 831 of the reinforcing plate 83 are respectively arranged inside the slit portion 81 in a plan view. In this way, since a pair of side edge portions 831 of the reinforcing plate 83 are arranged inside the slit portion 81, it becomes easier to hook a finger on the pair of side edge portions 831 of the reinforcing plate 83, and the reinforcing plate 83 becomes easier to hold.

[0131] The tab 84 is installed on the slit portion 81 so as to connect the portion B1 and the other portion B2 with the slit portion 81 interposed therebetween. In this way, by providing the tab 84, the portion B1 can be fixed before the second connector 31a is turned inside out.

[0132] Here, in the flexible substrate 31, even when the flexible substrate 31 is curved by inverting the portion B1 inside out and the adhesion between the flexible substrate 31 and the second connector 31a is disengaged, it is also dealt with.

[0133] If the adhesion between the flexible substrate 31 and the second connector 31a comes off, there is a risk of disconnection from the wiring pattern 85 (851) at the outermost end of the second connector 31a. In the present embodiment, the outermost wiring pattern 851 is configured to be able to detect disconnection. In this case, for example, if the outermost wiring pattern 851 is a GND line, a Hi-level signal can be detected at the time of disconnection. Thereby, it becomes possible to detect the disconnection of the wiring pattern 851.

[0134] Also, by making the outermost wiring pattern 851 a GND line thicker than other signal lines, it is possible to electrically reinforce and protect other signal lines (wiring patterns 85) from noise, and also to mechanically reinforce the flexible substrate 31. The mechanical reinforcement of the flexible substrate 31 is effective in a configuration where the flexible substrate 31 is likely to be stressed in order to reverse the front and back of the part B1 as in the present embodiment.

[0135] Also, as shown in FIG. 12, a wiring pattern 85 (852) is also formed on the tab 84. Therefore, it is possible to visually confirm whether or not the wiring pattern 852 is formed at an appropriate position on the tab 84 when the wiring pattern 85 is formed. Thereby, it can be utilized as a marker for inspecting whether or not the slit portion 81 is formed at an appropriate position.

[0136] <Another Embodiment of the Flexible Substrate> Next, another embodiment of the flexible substrate 31 will be described with reference to FIGS. 13 to 15. FIGS. 13 to 15 are explanatory views of another embodiment of the flexible substrate 31. Note that FIGS. 13 to 15 schematically show the flexible substrate 31 (31A to 31C). In such another embodiment, various variations of the slit portion 81 will be described.

[0137] As shown in FIG. 13, in the flexible substrate 31A according to another embodiment, the slit portion 81 is formed linearly along the width direction of the flexible substrate 31A. At the portion B1 formed in such a slit portion 81, the second connector 31a is turned inside out, so that the second connector 31a can reach farther.

[0138] As shown in FIG. 14, in the flexible substrate 31B according to another embodiment, the slit portion 81 is formed in a T shape at the central portion in the width direction of the flexible substrate 31A. Note that the “T shape” is a shape formed by one straight line and one straight line orthogonal to this straight line from the middle position of one straight line.

[0139] As shown in FIG. 15, in the flexible substrate 31C according to another embodiment, the slit portion 81 is formed in the following shape at the central portion in the width direction of the flexible substrate 31A. The slit portion 81 is a shape formed by two parallel first straight lines, one second straight line connecting the ends of the first straight lines, and one third straight line orthogonal to the second straight line from the middle position of the second straight line. At the portion B1 formed by such a slit portion 81, the degree of freedom in the position of the second connector 31a is high. As a result, the flexible substrate 31A can keep the length in the height direction (the vertical direction shown in FIG. 15) of the flexible substrate 31A small while allowing the second connector 31a to reach farther.

[0140] According to the droplet discharge head 8 according to the embodiment described above, the head substrate 32 and the flexible substrate 31 can be B-to-B connected via connectors (the first connector 32a and the second connector 31a). Therefore, the head substrate 32 and the flexible substrate 31 can be firmly connected, and the reliability can be improved.

[0141] Further, when the second connector 31a is turned inside out, the second connector 31a can reach farther. That is, the flexible substrate 31 extends. As a result, a margin is created between the second connector 31a and the first connector 32a, enabling a good B-to-B connection between the head substrate 32 and the flexible substrate 31.

[0142] Also, for example, when the side of the flexible substrate 31 is a terminal with respect to the first connector 32a, since a terminal such as tin is connected to a connector using gold plating, so-called dissimilar-metal corrosion occurs in which the tin melts due to the adhesion of moisture or the like. In such a case, generally, since the terminals on the flexible substrate 31 such as COF cannot be gold-plated, measures against dissimilar-metal corrosion other than gold plating are required.

[0143] According to the droplet discharge head 8 according to the embodiment, as described above, since the head substrate 32 and the flexible substrate 31 can be B-to-B connected, that is, since different metals are not used, the occurrence of dissimilar-metal corrosion can be suppressed.

[0144] Also, when connectors are used for both the head substrate 32 and the flexible substrate, it is difficult to perform B-to-B connection because there is a limit on the height of the flexible substrate 31. However, according to the droplet discharge head 8 according to the embodiment, as described above, when the second connector 31a is turned inside out, the second connector 31a can reach farther.

[0145] In addition, since the flexible substrate 31 can be turned inside out by the U-shaped slit portion 81, the second connector 31a can be mounted on the same surface as the terminals (actuator-side terminals) and the driver IC 33 mounted on the flexible substrate 31. As a result, a single-layer flexible substrate 31 can be used, and cost reduction can be achieved.

[0146] In addition, since a part (upper edge portion 311) of the portion B1 on the flexible substrate 31 is separated from the other portion B2, the portion B1 is not restricted. As a result, the portion B1 can be deformed flexibly.

[0147] In addition, since the rounded portion 82 is formed at the base end portion of the slit portion 81, the concentration of stress at the base end portion of the slit portion 81 can be reduced. Thereby, breakage of the flexible substrate 31 can be suppressed.

[0148] In addition, by reinforcing the second connector 31a with the reinforcing plate 83, the effect of suppressing breakage of the second connector 31a when attaching / detaching to / from the first connector 32a can be improved.

[0149] In addition, since the pair of side edge portions 831 of the reinforcing plate 83 protrude inside the slit portion 81, the reinforcing plate 83 is easier to hold when attaching / detaching to / from the first connector 32a. Thereby, the handling property can be improved.

[0150] In addition, by providing the tab 84 in the slit portion 81, the portion B1 can be fixed before the second connector 31a is turned inside out. Thereby, the handling property can be improved.

[0151] In addition, since the wiring pattern 852 is also formed on the tab 84, this wiring pattern 852 can be utilized as a marker for inspecting whether the slit portion 81 is formed at an appropriate position.

[0152] In addition, according to the recording apparatus 1 according to the embodiment, in the droplet discharge head 8, the head substrate 32 and the flexible substrate 31 can be B-to-B connected via connectors (the first connector 32a and the second connector 31a). Therefore, the head substrate 32 and the flexible substrate 31 can be firmly connected, and the reliability can be improved.

[0153] Also, when the second connector 31a is turned over, the second connector 31a can reach farther. That is, the flexible substrate 31 extends. As a result, a margin is created between the second connector 31a and the first connector 32a, enabling a good B-to-B connection between the head substrate 32 and the flexible substrate 31.

[0154] In the above-described embodiment, the slit portion 81 has a predetermined width. However, for example, the slit portion 81 may be formed by a linear cut. Even when the slit portion 81 is a linear cut, the portion B1 can be turned over.

[0155] Further effects and modifications can be easily derived by those skilled in the art. Therefore, the broader aspects of the present invention are not limited to the specific details and representative embodiments shown and described above. Accordingly, various changes can be made without departing from the spirit or scope of the general inventive concept defined by the appended claims and their equivalents.

Explanation of Reference Numerals

[0156] 1 Recording device 8 Droplet ejection head 31 Flexible substrate 31a Second connector 32 Head substrate 32a First connector 33 Driver IC 81 Slit portion 82 Rounded portion 83 Reinforcing plate 84 Tab 831 Side edge portion 852 Wiring pattern B1 Portion B2 Portion

Claims

1. A head body that discharges droplets, A driver IC that controls the driving of the head body, A flexible substrate on which the driver IC is mounted and electrically connected to the head body, A head substrate having a first connector and comprising The flexible substrate has a second connector corresponding to the first connector, and the second connector can be turned over front to back, The second connector is connected to the first connector in a state where it is turned over front to back Droplet discharge head.

2. The flexible substrate is formed such that the portion on which the second connector is mounted can be turned over front to back The droplet discharge head according to Claim 1.

3. The flexible substrate has a U-shaped slit portion formed so as to surround the portion on which the second connector is mounted The droplet discharge head according to Claim 1 or 2.

4. The flexible substrate has a rounded portion formed at the base end of the slit portion The droplet discharge head according to Claim 3.

5. The flexible substrate has a reinforcing plate on the back surface of the portion on which the second connector is mounted The droplet discharge head according to Claim 1.

6. The flexible substrate has a reinforcing plate on the back surface of the portion on which the second connector is mounted, The reinforcing plate is provided so as to cover the portion on which the second connector is mounted, and the side edge portion of the reinforcing plate protrudes from the portion on which the second connector is mounted to the inside of the slit portion The droplet discharge head according to Claim 3.

7. The flexible substrate has a tab that connects the portion on which the second connector is mounted and the portion other than the portion on which the second connector is mounted in the slit portion The droplet discharge head according to Claim 3.

8. A wiring pattern is formed on the tab of the flexible substrate The droplet discharge head according to Claim 7.

9. Comprising the droplet discharge head according to Claim 1 Recording device.

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