JP2011253858A - Wiring board unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To minimize the number of interconnections on a first wiring board mounting a drive IC.SOLUTION: In the wiring board unit 50, a COF 52 is arranged to face the top surface where individual lands 43 or lands 45 for ground of an actuator unit 31 are formed, and an FPC 51 is stacked on the COF 52 on the opposite side of the actuator unit 31. Bumps 57 for ground formed on the FPC 51 are exposed from through holes 66 formed in the COF 52, and the apexes thereof are arranged on the same plane as the apexes of bumps 64 for driving formed on the COF 52. The bumps 64 for driving and the bumps 57 for ground are connected to the individual lands 43 or the lands 45 for ground of the actuator unit 31.

Description

  The present invention relates to a wiring board unit connected to a plurality of connection terminals arranged on a connection surface of an actuator.

  Conventionally, there is a wiring board that is connected to an actuator having a plurality of driving elements and performs signal transmission, power supply, and the like. The wiring board is provided with a drive IC that is controlled by the control board and drives a plurality of drive elements. The drive IC is driven by a plurality of drive elements when a signal or power is input from the control board. Output a signal.

  In general, the control board and the actuator are connected by a single wiring board on which the driving IC is mounted. However, the wiring board on which the driving IC is mounted is a driving signal from the driving IC to a number of driving elements of the actuator. Since it is necessary to form a large number of output wirings with a narrow wiring pitch, it has special specifications such as requiring high wiring formation technology and expensive resist material covering the wiring The cost is high.

  On the other hand, an input wiring to the drive IC is arranged between the control board and the drive IC. The input wiring to the driving IC is for supplying a signal for generating a driving signal by the driving IC, but the number of wirings is generally very small compared to the output wiring of the driving IC. Therefore, by connecting the wiring board on which the driving IC is mounted and the control board with another wiring board on which the input wiring is formed, a general-purpose one can be used for this other wiring board, which is very expensive. Costs can be reduced because nothing is needed.

  For example, in the field of a recording apparatus provided with a large number of drive elements for recording images and characters on a recording medium such as recording paper, a wiring board unit connected to an actuator of an inkjet head described in Patent Document 1 As described above, the configuration from the control unit that controls the drive IC to the actuator is composed of a cable (second wiring board) in which only wiring is formed in order from the control unit side and a wiring board (first wiring board) on which the driving IC is mounted. ) Are connected to form a wiring board unit, and the first wiring board on which the driving IC is mounted is connected to the actuator.

Japanese Patent Laying-Open No. 2006-103117 (FIG. 2)

  Incidentally, for example, in the field of the recording apparatus as described above, the number of drive elements has increased in recent years in order to meet the demand for high-speed printing and high-resolution printing. Then, as the number of driving elements increases, the number of terminals formed on the wiring board on which the driving IC is mounted corresponding to the driving elements also increases, and the number of wirings routed to these many terminals also increases. To increase. However, the wiring board is configured not to increase in size in order to avoid increasing the size of the recording apparatus. Therefore, when the number of wirings increases, it is necessary to make the wirings thinner or reduce the interval between the wirings. The wiring board on which the driving IC is mounted has a problem that costs increase when the wiring becomes thin or the interval between the wirings becomes small.

  Accordingly, an object of the present invention is to provide a wiring board unit that can be configured with a reduced number of wirings in the first wiring board on which the driving IC is mounted even when the number of driving elements is increased. is there.

  The wiring board unit of the present invention includes a driving IC that drives a plurality of driving elements of the actuator, and electrically connects the actuator and a control board that controls the driving IC. A wiring board unit connected to a connection surface on which a plurality of connection terminals corresponding to driving elements are disposed, wherein the wiring board unit is connected to the first wiring board on which the driving IC is mounted, the first wiring board, A second wiring board on which input wiring from the control board to the driving IC is formed, and the first wiring board and the second wiring board are connected and bent in an integrated state, The one wiring board is overlapped with the one wiring board so that the one wiring board faces the connection surface and the other wiring board sandwiches the one wiring board together with the actuator. The drive IC includes an input terminal connected to the input wiring of the second wiring board, and a plurality of drive signal output terminals for outputting drive signals to the plurality of drive elements, respectively. The first wiring board is provided with a first terminal connected to at least a part of the plurality of driving signal output terminals of the driving IC, and the second wiring board has the first wiring in a plan view. Connected to the second terminal for signals supplied from the control board directly to the actuator without passing through the drive IC, or the remainder of the drive signal output terminal, in an area that does not overlap with the first terminal of the board. A third terminal is provided, the terminal of the one wiring board facing the actuator is connected to the connection terminal of the connection surface of the actuator, and the terminal of the other wiring board Child, is exposed from the face of the terminal is formed of the one of the wiring substrate and connected to said connection terminals of said connecting surface of said actuator.

  According to the wiring board unit of the present invention, the terminals connected to the connection terminals on the connection surface of the actuator are provided not only on the first wiring board on which the drive IC is mounted but also on the second wiring board. The second wiring board has a smaller number of wirings than the first wiring board, and can secure a space for providing terminals after routing the wirings. Therefore, since the terminal connected to the actuator is provided separately for the first wiring board and the second wiring board, the wiring of the second wiring board is compared with the case where this terminal is provided only for the first wiring board. It is possible to reduce the number of terminals provided on the first wiring board by effectively utilizing a space in which no wiring is routed. Therefore, the number of wirings between the driving IC provided on the first wiring board and the first terminal can also be reduced. As a result, even if the number of drive elements increases, the number of terminals provided on the first wiring board is suppressed by increasing the number of terminals provided on the first wiring board by forming the terminals connected to the actuator only on the first wiring board. An increase in the number of wirings provided on one wiring board can be suppressed.

  The first wiring board faces the actuator across the second wiring board, and the first terminal of the first wiring board is arranged to face the second wiring board. The second wiring board is formed with a through hole that exposes the first terminal from the surface on which the terminal of the second wiring board is formed at a position facing the first terminal of the first wiring board. It is preferable. The first wiring board on which the driving IC is mounted has a narrow wiring pitch, and, for example, small foreign matters such as dust and dust are likely to adhere between the wirings and easily short circuit. Therefore, the surface of the first wiring board on which the wiring is formed may be protected with a resist. However, in the present invention, when the first wiring board and the second wiring board are overlapped, the surface on the actuator side on which the wiring routed to the terminal of the first wiring board is formed is the surface of the second wiring board. Since it is protected by the surface of the second wiring board in the vicinity of the facing surface, it is not necessary to form an expensive resist with high insulation due to the narrow wiring pitch, and the cost of the first wiring board is reduced. can do.

  Furthermore, it is preferable that the second wiring board is provided with the second terminal that is not connected to the driving IC. According to this, the second terminal provided on the second wiring board is a signal terminal that is directly supplied to the actuator from the control board without passing through the driving IC, and the driving IC mounted on the first wiring board. This is a signal terminal that does not need to be supplied to the circuit board, and the number of wirings routed from the second wiring board to the first wiring board can be reduced.

  The first wiring board is provided with a first connection wiring for connecting the drive signal output terminal and the first terminal, and the second wiring board is provided with the rest of the drive signal output terminal. The connected third terminal is provided, and the second wiring board is further connected to the first wiring board and the second wiring board from the driving signal output terminal of the driving IC of the first wiring board. And a second connection wiring connected to the third terminal may be provided. According to this, the 1st terminal and 3rd terminal which are terminals connected with a drive signal output terminal are divided and connected to the 1st wiring and the 3rd wiring. Therefore, the wiring for connecting to the drive signal output terminal is not concentrated on the first wiring board. Therefore, the number of wirings on the first wiring board on which the driving IC is mounted can be further suppressed.

  The first wiring board may be disposed between the second wiring board and the actuator. The number of terminals of the first wiring board is much larger than the number of terminals of the second wiring board. By arranging and connecting the first wiring board on the actuator side with respect to the second wiring board, the terminals of the first wiring board are reliably connected to the connection terminals on the connection surface of the actuator as compared with the terminals of the second wiring board. can do.

  At this time, the actuator has a constant potential electrode to which a constant potential is applied, and the second wiring board is provided with a plurality of the second terminals, and the plurality of second terminals are: It is preferable to be connected to the constant potential electrode. According to this, even if a force in a direction away from the actuator is applied to the second wiring board and some second terminals of the second wiring board are peeled off, all the second terminals of the second wiring board have Since the same constant potential is applied, a constant potential is applied to the constant potential electrode of the actuator from the second terminal that is not peeled off. The second terminal provided on the second wiring board is a signal terminal that is directly supplied from the control board to the actuator without passing through the driving IC, and is supplied to the driving IC mounted on the first wiring board. This is a signal terminal that does not need to be performed. Therefore, no wiring for connecting the drive signal output terminal and the second terminal of the drive IC is necessary, and the width of the first wiring board and the second wiring board in the arrangement direction of the plurality of wirings can be reduced.

  The wiring board unit of the liquid ejecting head ejects liquid from a plurality of nozzles, wherein the plurality of nozzles are different types of liquids at intervals in one direction parallel to the surface of the first wiring board. The first terminals of the first wiring board are arranged corresponding to the plurality of nozzles, and the second terminals of the second wiring board are arranged. The terminals are preferably arranged so as to overlap with a region between the two types of nozzle groups in plan view.

  Between the two types of nozzle groups, for example, when a partition plate for partitioning a cap for preventing nozzle drying or the like is arranged for each nozzle group, or when wiping the ejection surface on which a plurality of nozzles are formed with a wiper, It is formed in order to increase the distance so that different types of liquids do not easily mix, and is a space necessary for the liquid ejecting head. Then, correspondingly, a similar space is also formed in the wiring board. On the other hand, a large space is required to connect the terminal of the second wiring board facing the actuator across the first wiring board to the actuator. Therefore, by arranging a terminal to which a signal directly supplied to the actuator is input from the control board without going through the drive IC in the space of the wiring board, the area where the terminal is conventionally provided can be eliminated. The substrate unit can be reduced in size.

  The first wiring board is provided with a first connection wiring for connecting the drive signal output terminal and the first terminal, and the second wiring board is provided with the rest of the drive signal output terminal. The connected third terminal is provided, and the second wiring board is further connected to the first wiring board and the second wiring board from the driving signal output terminal of the driving IC of the first wiring board. And a second connection wiring connected to the third terminal may be provided. According to this, wiring is routed with a particularly narrow wiring pitch, and a part of the wiring is provided on the second wiring board as a third terminal instead of the first terminal connected to the drive signal output terminal. Therefore, the number of wirings on the first wiring board on which the driving IC is mounted can be further suppressed.

  On the other hand, in another aspect, the wiring board unit of the present invention has a drive IC that drives a plurality of drive elements of an actuator, and electrically connects the actuator and a control board that controls the drive IC. A wiring board unit connected to a connection surface on which a plurality of connection terminals respectively corresponding to the plurality of drive elements of the actuator are disposed, wherein the first wiring board on which the drive IC is mounted; and the first A second wiring board connected to the wiring board and formed with an input wiring from the control board to the driving IC, and the first wiring board and the second wiring board are connected and integrated. The first wiring board is bent so that the first wiring board faces the connection surface, and the second wiring board sandwiches the first wiring board together with the actuator. The drive IC includes an input terminal connected to the input wiring of the second wiring board, and a plurality of drive signal output terminals for outputting drive signals to the plurality of drive elements, respectively. The first wiring board is provided with a first terminal provided on one surface facing the connection surface and connected to at least some of the plurality of drive signal output terminals of the drive IC. The second wiring board is provided on a surface facing the first wiring board, and is disposed from the control board to the drive IC in a region that does not overlap the first terminal of the first wiring board in a plan view. A second terminal for a signal that is directly supplied to the actuator without passing through the first terminal, or a third terminal connected to the rest of the drive signal output terminal, and further, the first wiring board The second wiring board A fourth terminal provided on the other surface facing the second terminal or the third terminal, and a fourth terminal provided on the one surface and connected only to the fourth terminal via a through hole. Five terminals are provided, and the first terminal and the fifth terminal of the first wiring board are connected to the connection terminal of the connection surface of the actuator.

  According to the wiring board unit of the present invention, the wiring routed to the terminal connected to the connection terminal on the connection surface of the actuator is not limited to the first wiring board on which the driving IC is mounted, but also to the second wiring board. Provided. The second wiring board has a smaller number of wirings than the first wiring board, and can secure a space for providing other wirings after routing the input wirings. Therefore, since the arrangement can be provided separately for the first wiring board and the second wiring board, the number of wirings routed to the first wiring board is reduced as compared with the case where the wiring is provided only on the first wiring board. be able to. Therefore, the number of wirings on the first wiring board on which the driving IC is mounted can be suppressed. Further, the number of terminals of the first wiring board is much larger than the number of terminals of the second wiring board. By arranging the first wiring board closer to the actuator than the second wiring board, the terminals of the first wiring board can be reliably connected to the connection terminals on the connection surface of the actuator as compared with the terminals of the second wiring board. it can.

  Since the terminals connected to the connection terminals on the connection surface of the actuator are provided not only on the first wiring board on which the driving IC is mounted but also on the second wiring board, the wiring on the second wiring board is drawn. The number of terminals provided on the first wiring board can be reduced by effectively utilizing the unrotated space. Therefore, the number of wirings on the first wiring board on which the driving IC is mounted can be suppressed.

1 is a schematic configuration diagram of a printer according to an embodiment. It is a top view of an inkjet head. It is the sectional view on the AA line of FIG. It is the schematic which shows the connection structure of the actuator unit and control board by a wiring board unit. It is a side view when the wiring board unit connected to the actuator unit is viewed from the scanning direction. It is a top view of the wiring board unit before being bent and connected to the actuator unit. It is a side view when the wiring board unit connected to the actuator unit in the modification is viewed from the scanning direction, (a) is the case of Modification 1, and (b) is the case of Modification 2. FIG. 10 is a plan view of a wiring board unit before being bent and connected to an actuator unit in Modification 3; It is a figure explaining the modification 4, (a) is a top view of an inkjet head, (b) is a top view of the wiring board unit before being bent and connected to an actuator unit, (c) is It is BB sectional drawing of (b).

  Hereinafter, preferred embodiments of the present invention will be described. This embodiment is an example in which the present invention is applied to a wiring board unit provided in an inkjet printer that ejects ink from an inkjet head onto a recording sheet to record images, characters, and the like.

  First, a schematic configuration of the ink jet printer will be described. FIG. 1 is a schematic configuration diagram of a printer according to the present embodiment. As shown in FIG. 1, the printer 1 includes a carriage 2, an ink jet head 3 (liquid ejecting head), a transport roller 4, and the like.

  The carriage 2 reciprocates in the scanning direction (left and right direction in FIG. 1). The inkjet head 3 is attached to the lower surface of the carriage 2 and ejects ink from nozzles 35 (see FIG. 3) formed on the lower surface. The transport roller 4 transports the recording paper P in the paper feed direction (front side in FIG. 1). In the printer 1, ink is ejected from the nozzles 35 of the ink-jet head 3 that reciprocates in the scanning direction together with the carriage 2 onto the recording paper P conveyed in the paper feeding direction by the conveying roller 4. Images, characters, etc. are recorded on the. The recording paper P on which images, characters, etc. are recorded is discharged by the transport roller 4 in the paper feeding direction.

  Next, the inkjet head 3 will be described. FIG. 2 is a plan view of the inkjet head. FIG. 3 is a cross-sectional view taken along line AA in FIG. Note that FIG. 3 also shows a wiring board unit 50 (described later) disposed above the actuator unit 31. As shown in FIGS. 2 and 3, the inkjet head 3 includes a flow path unit 30 in which an ink flow path is formed, a piezoelectric actuator unit 31 that applies an ejection pressure to the ink in the ink flow path, and an actuator unit. A wiring board unit 50 that covers the upper surface of 31 and sends a signal from the control board 60 (see FIG. 4) to the actuator unit 31 is provided.

  First, the flow path unit 30 will be described. The flow path unit 30 has four ink supply ports 32 respectively connected to four ink cartridges (not shown), and the vertical direction (paper feed direction) in FIG. 2 branched from the ink supply port 32 and perpendicular to the scanning direction. Are formed, four manifolds 33 extending along the plurality of pressure chambers 34, a plurality of pressure chambers 34 communicating with the respective manifolds 33, and a plurality of nozzles 35 respectively communicating with the plurality of pressure chambers 34. The plurality of nozzles 35 and the plurality of pressure chambers 34 are arranged in the paper feed direction to form nozzle rows and pressure chamber rows, and such nozzle rows and pressure chamber rows are arranged in four rows in the scanning direction. Has been. Then, magenta, cyan, yellow, and black inks are ejected in order from the nozzles 35 belonging to the left nozzle row in FIG.

  Next, the actuator unit 31 will be described. The actuator unit 31 includes a diaphragm 40 joined to the flow path unit 30 so as to cover the plurality of pressure chambers 34, a piezoelectric layer 41 disposed on the upper surface of the diaphragm 40, and a plurality of pressures on the upper surface of the piezoelectric layer 41. A plurality of individual electrodes 42 provided corresponding to the chamber 34, a plurality of individual lands 43 formed at ends of the plurality of individual electrodes 42, and a paper feed direction at both ends of the upper surface of the piezoelectric layer 41 in the scanning direction. It has two ground electrodes 44 (constant potential electrodes) that are extended and always applied with a ground potential, and a plurality of ground lands 45 formed on the ground electrode 44. The individual lands 43 and the ground lands 45 in the present embodiment correspond to connection terminals in the present invention.

  The diaphragm 40 is made of a metal material, is connected to the ground electrode 44 through a through hole (not shown) formed in the piezoelectric layer 41, and is always kept at the ground potential. The actuator unit 31 is connected to the individual electrode 42 and the diaphragm when a pulse-like drive signal is supplied to the individual electrode 42 from a driver IC 53 (see FIG. 5) mounted on a COF 52 described later of the wiring board unit 50. Due to the electric field generated between the piezoelectric layers 41, the piezoelectric layer 41 in the meantime causes piezoelectric distortion, causing the diaphragm 40 to bend and deform. When the volume of the pressure chamber 34 fluctuates due to the bending deformation of the vibration plate 40, pressure is applied to the ink in the pressure chamber 34, and ink is ejected from the nozzle 35 communicating with the pressure chamber 34. The plurality of individual lands 43 are arranged side by side at a predetermined interval in the paper feed direction corresponding to the plurality of nozzles 35, and this row is arranged in four rows in the scanning direction. In addition, the part which produces the piezoelectric distortion of the piezoelectric layer 41 in this embodiment corresponds to the drive element in the present invention.

  Next, the wiring board unit 50 will be described. FIG. 4 is a schematic diagram showing a connection configuration between the actuator unit and the control board by the wiring board unit. FIG. 5 is a side view when the wiring board unit connected to the actuator unit is viewed from the scanning direction. FIG. 6 is a plan view of the wiring board unit before being bent and connected to the actuator unit.

  As shown in FIG. 4, the wiring board unit 50 includes a flexible wiring board 52 (Chip On Film: COF) on which a driver IC 53 (driving IC) is mounted, and a flexible wiring board 51 (which connects the COF 52 and the control board 60). Flexible Printed Circuits (FPC). Although not shown, a flexible flat cable (FFC) is relayed between the FPC 51 and the control board 60.

  As shown in FIG. 5, the wiring board unit 50 has a COF 52 disposed so as to face the upper surface (connection surface) on which the individual lands 43 and the ground lands 45 of the actuator unit 31 are formed, and the actuator unit of the COF 52 An FPC 51 is placed on the opposite side of 31.

  The control board 60 transmits input signals such as CLK, Fire, and SIN to the driver IC 53, respectively. CLK is a data transfer clock from the control board 60 to the driver IC 53. Fire does not eject droplets to one nozzle 35, and six types of driving waveforms respectively corresponding to a total of six types of ejection modes of five types of droplet ejection sizes (droplet volumes) corresponding to gradations. Serial data that transmits data in series. The SIN is serial data that serially transmits selection data for associating the driver IC 53 with one of six types of ejection modes to the ejection timing of each nozzle 35. Further, the control board 60 directly transmits a ground signal having a ground potential to the ground electrode 44 of the actuator unit 31 without using the driver IC 53.

  As shown in FIGS. 4 to 6, the driver IC 53 includes a plurality of input terminals 53 a to which input signals from the control board 60 are input, and a plurality of drive signals for outputting drive signals to the plurality of individual electrodes 42, respectively. And an output terminal 53b. The driver IC 53 generates a drive waveform for each individual electrode 42 from among the drive waveform data corresponding to the six types of ejection modes transmitted by Fire according to an input signal input from the control board 60 to the input terminal 53a. Data is selected, the selected drive waveform data is amplified to a voltage suitable for the actuator unit 31, and is output from the drive signal output terminal 53b to the individual electrodes 42 of the actuator unit 31 as drive signals.

  Note that the number of drive signal output terminals 53b of the driver IC 53 is much larger than the number of input terminals 53a. This is because the signal input to the input terminal 53a is serial data such as Fire and SIN and CLK (data transfer clock), and the number of signals is small, whereas the signal output from the drive signal output terminal 53b is This is because the drive signals are individually output to the plurality of individual electrodes 42, and the number of signals is required by the number of the individual electrodes 42.

  As shown in FIG. 6, the FPC 51 (second wiring substrate) is made of an insulating resin material such as polyimide, and has a flexible substrate 55 and a plurality of first input wirings 56 formed on the substrate 55. Of the plurality of first input wirings 56, connected to the ground first input wiring 56a to which the ground signal is input, and connected to the ground land 45 formed on the upper surface of the piezoelectric layer 41 of the actuator unit 31. A bump 57 (second terminal) and a resist 58 that covers the substrate 55 and the first input wiring 56 while exposing the ground bump 57 are provided. The first ground input wiring 56a extends in the Y direction on both sides in the X direction of the FPC 51, and three ground bumps 57 are arranged at intervals along the extending direction. The plurality of first input wirings 56 excluding the ground first input wiring 56a are arranged at intervals in the X direction at the center in the X direction of the FPC 51 and extend in the Y direction.

  The COF 52 (first wiring substrate) is made of an insulating resin material such as polyimide, and has a flexible substrate 61 and a plurality of first input wirings 56 formed on the substrate 61, excluding the ground first input wirings 56a. And a plurality of second input wirings 62 connecting the plurality of input terminals 53a of the driver IC 53, a plurality of output wirings 63 (first connection wirings) connected to the plurality of drive signal output terminals 53b of the driver IC 53, and an output wiring 63, and the driving bump 64 (first terminal) connected to the individual electrode 42 formed on the upper surface of the piezoelectric layer 41 of the actuator unit 31 and the driving bump 64 are exposed, while the substrate 61, A resist 65 that covers the second input wiring 62 and the output wiring 63 and a through hole 66 that faces the ground bump 57 when overlapped with the FPC 51 are provided. The plurality of output wirings 63 are routed from the plurality of driving signal output terminals 53b of the driver IC 53 to the plurality of driving bumps 64 so as not to intersect with other wirings.

  The FPC 51 and the COF 52 are connected so that the surface on which the various wirings and bumps of the FPC 51 are formed and the surface on which the various wirings and bumps of the COF 52 are not formed are the same surface. ing. In such a configuration of the wiring board unit 50, as shown in FIG. 5, the COF 52 is arranged such that the surface of the FPC 51 where the various wirings and bumps are formed faces the surface of the COF 52 where the various wirings and bumps are not formed. When the COF 52 and the FPC 51 are folded and overlapped, the ground bump 57 formed in the FPC 51 is exposed from the through hole 66 formed in the COF 52, and the apex thereof is the apex of the driving bump 64 formed in the COF 52. Arranged on the same plane.

  Next, connection between the wiring board unit 50 and the actuator unit 31 will be described. First, the surface on which various wirings and bumps of the COF 52 are formed is opposed to the upper surface of the piezoelectric layer 41 of the actuator unit 31 so that the paper feed direction and the Y direction are parallel to each other. At this time, the driving bumps 64 formed on the COF 52 and the plurality of individual lands 43 formed on the upper surface of the piezoelectric layer 41 of the actuator unit 31 are aligned and connected. Then, the through hole 66 formed in the COF 52 and the ground land 45 formed on the upper surface of the piezoelectric layer 41 face each other.

  Thereafter, when the COF 52 is bent and the FPC 51 is overlaid on the COF 52, the ground bumps 57 formed on the FPC 51 are exposed from the through holes 66 formed in the COF 52. The ground bumps 57 exposed from the through holes 66 of the COF 52 are connected without being aligned with the ground lands 45 formed on the upper surface of the piezoelectric layer 41.

  Here, as described above, the number of output wirings 63 that output drive signals to the plurality of individual electrodes 42 as compared to the number of first input wirings 56 and second input wirings 62 to which serial data or the like is input. Has become very much. Therefore, in the COF 52, the routing of the output wiring 63 from the driving signal output terminal 53b of the driver IC 53 to the driving bump 64 has a narrow wiring pitch and is complicated. Therefore, in the present embodiment, bumps connected to various lands and electrodes on the upper surface of the piezoelectric layer 41 of the actuator unit 31 are provided not only on the COF 52 on which the driver IC 53 is mounted but also on the FPC 51. Specifically, the ground bumps 57 to which the ground lands 45 are also connected are provided not on the COF 52 but on the FPC 51. The FPC 51 has a smaller number of wires than the COF 52, and can secure a sufficient space for providing bumps after routing the wires. Therefore, it is possible to effectively utilize the space in which the wiring of the FPC 51 is not routed, reduce the number of bumps provided in the COF 52, and suppress the number of wirings in the COF 52.

  Further, since the FPC 51 and the COF 52 are connected and overlapped, the wiring board unit 50 can be reduced in size in the stacking direction. Further, when a force in a direction away from the actuator unit 31 is applied to the FPC 51 or the COF 52, not all the bumps are formed on the COF 52, and some of the bumps are formed on the FPC 51. Therefore, the bumps of the COF 52 and the FPC 51 The force can be distributed to the bumps, the bonding strength is high, and the displacement and peeling of the wiring board unit 50 from the actuator unit 31 can be prevented.

  Further, as described above, the number of bumps of the COF 52 is much larger than the number of bumps of the FPC 51. By arranging and connecting the COF 52 having a large number of bumps closer to the actuator unit 31 than the FPC 51, the bumps of the COF 52 can be reliably connected to the land on the upper surface of the piezoelectric layer 41 of the actuator unit 31 as compared to the bumps of the FPC 51. Can do.

  The ground bumps 57 provided on the FPC 51 are ground signal bumps directly supplied from the control board 60 to the actuator unit 31 without passing through the driver IC 53, and are supplied to the driver IC 53 mounted on the COF 52. This is a signal bump that is not necessary. Accordingly, there is no need for wiring for connecting the drive signal output terminal 53b of the driver IC 53 and the ground bump 57, and the number of wirings routed to the COF 52 can be reduced.

  Further, even if a force in a direction away from the actuator unit 31 is applied to the FPC 51 and some ground bumps 57 of the FPC 51 are separated from the ground electrode 44 of the actuator unit 31, all the ground bumps 57 of the FPC 51 Since a ground potential that is the same constant potential is applied, the ground potential is applied to the ground electrode 44 of the actuator unit 31 from the ground bump 57 that is not peeled off.

  Next, modified examples in which various changes are made to the present embodiment will be described. However, those having the same configuration as that of the above-described embodiment are denoted by the same reference numerals and description thereof is omitted as appropriate.

  In the present embodiment, the COF 52 is disposed opposite to the upper surface of the actuator unit 31 and the FPC 51 is overlaid thereon. However, as illustrated in FIG. 7A, the COF 52 is opposed to the upper surface of the actuator unit 31. The FPC 51 may be disposed, and the COF 52 may be overlaid thereon (Modification 1). At this time, the FPC 51 is formed with a through hole 90 through which the driving bump 64 of the COF 52 passes. The COF 52 on which the driver IC 53 is mounted has a narrow wiring pitch, and, for example, small foreign matters such as dust and dust are likely to adhere between the wirings and easily short circuit. Therefore, as in this embodiment, the surface on which the wiring of the COF 52 is formed may be protected with a resist. However, in this modification, when the COF 52 and the FPC 51 are overlapped, the surface on the actuator unit 31 side where the wiring of the COF 52 is formed is close to the surface facing the FPC 51 and is protected by the surface of the FPC 51. Therefore, it is not necessary to form a resist, and the cost of the COF 52 can be reduced. In addition, the manufacturing process for forming the resist can be simplified.

  In this embodiment, the bumps connected to the lands of the actuator unit 31 are formed separately for the FPC 51 and the COF 52. However, all output bumps are formed on the COF 52, and the drive signal output terminal 53b of the driver IC 53 is formed. It is also possible to divide the output wiring 63 to the driving bump 64 separately into the FPC 51 and the COF 52 (Modification 2). Hereinafter, a specific example will be described with reference to FIG.

  In the present embodiment, as shown in FIG. 5, the ground bumps 57 formed on the FPC 51 are exposed through the through holes 66 of the COF 52, but in this modification, no through holes are formed in the COF 52. . 7B, ground bumps 257 and first connection bumps 259 (fourth terminals) connected to the ground bumps 257 via the through holes 258 are formed on the COF 252. As shown in FIG. The second connection bump 260 (fifth terminal) connected to the first connection bump 259 is formed on the FPC 251. The second connection bump 260 corresponds to the ground bump 57 in the present embodiment, and is connected to the ground first input wiring 56a. This also has the same effect as the above-described embodiment. In addition, since the plurality of output bumps connected to the actuator unit 31 are all formed in the COF 252, compared to the case where some ground bumps 57 are formed in the FPC 51 as in the above-described embodiment, The contact height is likely to be uniform, and poor connection of the actuator unit 31 with the land can be reduced. Further, the second modification can be applied even when the arrangement of the FPC 51 and the COF 52 is reversed as in the first modification.

  Further, in the present embodiment, the ground bumps 57 for ground signals transmitted directly from the control board 60 to the actuator unit 31 without passing through the driver IC 53 are formed on the FPC 51 separately from the COF 52. The bumps divided into the FPC 51 may be driving bumps 64 that are input from the driver IC 53 to the individual electrodes 42 (Modification 3). For example, as shown in FIG. 8, a part of the driving bump 364 which is separated from the driver IC 53 and is formed in the COF 352 and which is difficult to route the output wiring may be formed separately in the FPC 351. The driving bump 364a (third terminal) formed on the FPC 351 is connected to the driving signal output terminal 53b of the driver IC 53 via the second output wiring 365 (second connection wiring). When the FPC 351 and the COF 352 are overlapped, a through hole 366 is formed at a position of the COF 352 facing the driving bump 364a of the FPC 351, and the driving bump 364a is exposed from the through hole 366. The ground bump 357 is formed on the COF 352. The ground bump 57 may be formed on the FPC 351 as in the present embodiment. According to this, the second output wiring 365 that is routed from the COF 352 to the FPC 351 and connects the drive signal output terminal 53 b and the drive bump 364 a formed on the FPC 351, and is routed from the FPC 351 to the COF 352 and input to the driver IC 53. Since the first input wiring 56 connected to the terminal 53a has a reverse signal transmission direction, the direction of current flow is reverse. Therefore, the magnetic field formed around the mutual wiring between the two wirings is canceled out, and noise on the signal can be reduced.

  Further, in the present embodiment, as shown in FIG. 2, the ground electrode 44 and the ground land 45 are formed on both sides in the scanning direction of the actuator unit 31, but as shown in FIG. , A nozzle array 35 for ejecting magenta, cyan, and yellow color inks, and a nozzle array for ejecting black ink, such as a nozzle array group 420 for ejecting black ink, are arranged between nozzles 35. This is different when a partition plate for partitioning a cap (not shown) for preventing the drying of the nozzle group for each nozzle group or when wiping the ejection surface on which the plurality of nozzles 35 are formed with a wiper (not shown). A gap 400 is formed in order to increase the distance so that different types of liquids do not easily mix, and this is a necessary space for the inkjet head 403. There.

  Then, as shown in FIGS. 9B and 9C, a space 430 corresponding to the gap 400 is also formed in the wiring board unit 450. On the other hand, a large space is required to connect the ground bump 457 of the FPC 451 facing the actuator across the COF 452 to the ground land 45 of the actuator unit 31. Therefore, in the space of the wiring board unit 450, a ground bump 457 to which a ground signal supplied directly from the control board 60 to the actuator unit 31 without passing through the driver IC 53 is input. When the FPC 451 and the COF 452 are overlapped, a through hole 466 is formed at a position of the COF 452 facing the ground bump 457 of the FPC 451, and the ground bump 457 is exposed from the through hole 466. As a result, the area where the ground bumps 457 are conventionally provided can be eliminated, and the wiring board unit 450 can be reduced in size.

  Further, the signal directly supplied from the control board 60 to the actuator unit 31 without passing through the driver IC 53 is not limited to the ground signal, and, for example, two sheets as described in JP 2009-96173 A Piezoelectric layers are stacked on top of each other. A plurality of individual electrodes and a fixed ground are provided at different positions in the thickness direction between the upper surface of the upper piezoelectric layer, the two piezoelectric layers, and the lower surface of the lower piezoelectric layer. For the actuator unit in which the common electrode held at the potential and the common electrode held at the constant drive potential are arranged, a signal to which the constant drive potential is input may be used.

  In the present embodiment, as a configuration for connecting the two contacts, a bump is used on the wiring board unit 50 side, and a land is used on the actuator unit 31 side, and the bump and the land are connected. However, bumps are used for the respective contacts, and the bumps may be connected to each other. The land is used on the wiring board unit 50 side, and the bumps are used on the actuator unit 31 side. In this case, the bump and the land may be connected.

  In the present embodiment, the ground bump 57 formed on the FPC 52 is exposed to the actuator unit 31 side through the through hole 66 of the COF 51. However, the through hole 66 is not formed in the COF 51, and the FPC 52 And the COF 51 may be overlapped so that the ground bumps 57 formed on the FPC 52 may not be opposed to the COF 51 and may be exposed to the actuator unit 31 side from the shifted position.

  Furthermore, the wiring board unit 50 described in the present embodiment can be adjusted in its posture by contacting the driver IC 53 and pressing it toward the actuator unit 31 with a heat sink that cools the driver IC 53.

  Further, the driving bumps 64 formed on the COF 52 are arranged side by side in the Y direction to form a row, and this row is arranged in the X direction orthogonal to the Y direction. There is no regularity about arrangement | positioning and you may arrange | position at random.

  Further, the driver IC 53 is disposed and a flexible board is used as the COF 51 connected to the actuator unit 31. However, the driver IC 53 is not necessarily a flexible board, and is a hard printed board near the boundary between the COF 51 and the FPC 52. It is sufficient that only the portion to be bent has flexibility.

  In the above-described embodiments and modifications thereof, the present invention is applied to the wiring board unit for driving the actuator of the inkjet head. However, the application target of the present invention is not limited to such a wiring board unit. Regardless of its use, the present invention can be applied to a wiring board unit that performs transmission of various signals, power supply, and the like.

DESCRIPTION OF SYMBOLS 1 Printer 3 Inkjet head 31 Actuator unit 43 Individual land 45 Land for ground 50 Wiring board unit 51 COF
52 FPC
53 Driver IC
53a input terminal 53b drive signal output terminal 56 first input wiring 56a first input wiring for ground 57 bump for ground 60 control board 62 second input wiring 63 output wiring 64 bump for driving

Claims (9)

A drive IC that drives the plurality of drive elements of the actuator, and electrically connects the actuator and a control board that controls the drive IC, and a plurality of drive ICs respectively corresponding to the plurality of drive elements of the actuator A wiring board unit connected to a connection surface on which connection terminals are arranged,
A first wiring board on which the driving IC is mounted;
A second wiring board connected to the first wiring board and formed with an input wiring from the control board to the driving IC,
The first wiring board and the second wiring board are connected and bent in an integrated state, one wiring board faces the connection surface, and the other wiring board and the actuator together with the one wiring. It is overlaid on the one wiring board so as to sandwich the board,
The drive IC includes an input terminal connected to the input wiring of the second wiring board, and a plurality of drive signal output terminals for outputting drive signals to the plurality of drive elements, respectively.
The first wiring board is provided with a first terminal connected to at least a part of the plurality of drive signal output terminals of the drive IC,
In the second wiring board, a signal first signal supplied from the control board to the actuator without passing through the driving IC is provided in a region not overlapping the first terminal of the first wiring board in plan view. A second terminal or a third terminal connected to the rest of the drive signal output terminal is provided;
A terminal of the one wiring board facing the actuator is connected to the connection terminal of the connection surface of the actuator, and a terminal of the other wiring board is formed of a terminal of the one wiring board. A wiring board unit exposed from a surface and connected to the connection terminal of the connection surface of the actuator. The first wiring board faces the actuator across the second wiring board,
The first terminal of the first wiring board is disposed to face the second wiring board;
The second wiring board is formed with a through hole that exposes the first terminal from the surface on which the terminal of the second wiring board is formed at a position facing the first terminal of the first wiring board. The wiring board unit according to claim 1, wherein:   The wiring board unit according to claim 1, wherein the second wiring board is provided with the second terminal that is not connected to the driving IC. The first wiring board is provided with a first connection wiring for connecting the drive signal output terminal and the first terminal;
The second wiring board is provided with the third terminal connected to the rest of the drive signal output terminal,
The first wiring board and the second wiring board further extend from the driving signal output terminal of the driving IC of the first wiring board to the second wiring board and are connected to the third terminal. The wiring board unit according to claim 1, wherein two connection wirings are provided.   2. The wiring board unit according to claim 1, wherein the first wiring board is disposed between the second wiring board and the actuator. 3. The actuator has a constant potential electrode to which a constant potential is applied,
The second wiring board is provided with a plurality of the second terminals,
The wiring board unit according to claim 5, wherein the plurality of second terminals are connected to the constant potential electrode. A wiring board unit of a liquid ejecting head that ejects liquid from a plurality of nozzles,
The plurality of nozzles are arranged in two groups of nozzles that eject different types of liquid at intervals in one direction parallel to the surface of the first wiring board,
The first terminals of the first wiring board are arranged corresponding to the plurality of nozzles;
The wiring board unit according to claim 6, wherein the second terminal of the second wiring board is arranged to overlap an area between the two types of nozzle groups in a plan view. The first wiring board is provided with a first connection wiring for connecting the drive signal output terminal and the first terminal;
The second wiring board is provided with the third terminal connected to the rest of the drive signal output terminal,
The first wiring board and the second wiring board further extend from the driving signal output terminal of the driving IC of the first wiring board to the second wiring board and are connected to the third terminal. The wiring board unit according to claim 5, wherein two connection wirings are provided. A drive IC that drives the plurality of drive elements of the actuator, and electrically connects the actuator and a control board that controls the drive IC, and a plurality of drive ICs respectively corresponding to the plurality of drive elements of the actuator A wiring board unit connected to a connection surface on which connection terminals are arranged,
A first wiring board on which the driving IC is mounted;
A second wiring board connected to the first wiring board and formed with an input wiring from the control board to the driving IC,
The first wiring board and the second wiring board are connected and bent in an integrated state, the first wiring board faces the connection surface, and the second wiring board together with the actuator is the first wiring board. Overlaid on the first wiring board so as to sandwich the wiring board,
The drive IC includes an input terminal connected to the input wiring of the second wiring board, and a plurality of drive signal output terminals for outputting drive signals to the plurality of drive elements, respectively.
The first wiring board is provided with a first terminal provided on one surface facing the connection surface and connected to at least a part of the plurality of drive signal output terminals of the drive IC;
The second wiring board is provided on a surface facing the first wiring board, and is routed from the control board via the drive IC to a region that does not overlap the first terminal of the first wiring board in a plan view. A second terminal for a signal supplied directly to the actuator without being connected, or a third terminal connected to the rest of the drive signal output terminal,
Further, the first wiring substrate is provided on the other surface facing the second wiring substrate, provided on the one surface, and a fourth terminal connected to the second terminal or the third terminal. A fifth terminal connected to only the fourth terminal through a through hole is provided;
The wiring board unit, wherein the first terminal and the fifth terminal of the first wiring board are connected to the connection terminal of the connection surface of the actuator.

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