JP2012206414A - Piezoelectric actuator system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a piezoelectric actuator system which can suppress to the utmost the difference in rising and falling of voltage between piezoelectric elements in a plurality.SOLUTION: FPC 45 includes a substrate, a first wiring part 48a including wiring 71 to connect bumps 47a belonging to a bump row disposed on the substrate, with driving IC 46a, and a second wiring part 48b including two lines 75 and 76 of wiring which connect a bump 47b belonging to the bump row and being more separate from the driving IC 46a than the bumps 47a, with the driving IC 46a.

Description

  The present invention relates to a piezoelectric actuator device.

  Conventionally, piezoelectric actuator devices having piezoelectric elements have been used in various technical fields. For example, Patent Document 1 discloses a piezoelectric actuator device used in an ink jet head having a nozzle row in which a plurality of nozzles are arranged side by side.

  The piezoelectric actuator device of Patent Document 1 includes an inkjet head and a wiring board connected to the inkjet head. Specifically, the inkjet head is provided with a plurality of piezoelectric elements for applying pressure for ejecting ink from each of the plurality of nozzles, and an input conduction point for inputting a signal for driving each piezoelectric element. A plurality of are formed. On the other hand, the wiring board has a plurality of connection contacts respectively connected to a plurality of conduction points, a drive IC that outputs a signal, and a plurality of wirings that connect the drive IC and the plurality of conduction contacts. The ink jet head and the wiring board are connected so that the nozzle row extends away from the drive IC.

JP 2007-196544 A

  In recent years, in an inkjet head, the number of nozzles has increased in order to realize high image quality and high-speed printing, and accordingly, the nozzle row is formed longer. When the nozzle row becomes longer, the difference in distance between the nozzle at one end of the nozzle row closest to the drive IC and the nozzle at the other end of the nozzle row farthest from the drive IC increases. Accordingly, the length of the wiring connecting the connection contact connected to the conduction point connected to the piezoelectric element for the nozzle on one end and the drive IC, and the connection contact connected to the conduction point connected to the piezoelectric element for the nozzle on the other end and the drive IC The lengths of the wiring connecting the two are greatly different. As a result, the rise and fall of the voltage applied to the piezoelectric element for the nozzle at one end and the rise and fall of the voltage applied to the piezoelectric element for the nozzle at the other end are greatly different, and the difference in discharge speed between the two nozzles. Becomes larger. For this reason, there is a problem that the print image quality is greatly affected.

  Therefore, an object of the present invention is to provide a piezoelectric actuator device that can suppress the difference in rising and falling of voltage between a plurality of piezoelectric elements as much as possible in a piezoelectric actuator having a plurality of conduction points.

  According to a first aspect of the present invention, there is provided a piezoelectric actuator device including: a piezoelectric actuator having a plurality of piezoelectric elements; and a plurality of input conduction points that respectively conduct to the piezoelectric elements; a base; and the piezoelectric actuator disposed on the base A driving IC that outputs a driving signal for driving the wiring board, and a wiring board that is disposed on the base material, is connected to the driving IC, and has a plurality of connection contacts that are connected to the plurality of conduction points. The material includes a connection contact row configured by arranging the plurality of connection contacts in an arrangement direction away from the drive IC, and a first wire including a first connection contact belonging to the connection contact row and the drive IC. A wiring section, and a second wiring that belongs to the connection contact row and includes a wiring that connects the drive IC to a second connection contact that is farther from the drive IC than the first connection contact in the arrangement direction. Has a line portion, the second wiring portion is at least partially, characterized in that it comprises a plurality of wirings larger than the number of lines included in the first wiring part.

  When the wiring connecting the connection contact and the drive IC becomes long, the wiring resistance corresponding to the electrical resistance between the connection contact and the drive IC increases. On the other hand, when the number of wirings connecting the connection contacts and the driving IC is increased, the wiring resistance between a certain connection contact and the driving IC is smaller than when the number of wirings is small. According to the present invention, the second wiring portion has a portion where the number of wirings connecting the driving IC and the connection contact is larger than that of the first wiring portion. As a result, the wiring resistance between the second connection contact and the driving IC is smaller than the wiring resistance between the first connection contact and the driving IC. Thereby, the difference of the rise and fall of the voltage of the piezoelectric element connected to the first connection contact and the piezoelectric element connected to the second connection contact can be suppressed as much as possible.

  According to a second aspect of the present invention, the piezoelectric actuator device according to the first aspect is characterized in that the first wiring portion has one wiring for connecting the first connection contact and the driving IC.

  According to the present invention, since the first wiring portion is formed of a single common wiring connecting the first connection contact and the driving IC, the wiring board can be easily designed.

  According to a third aspect of the present invention, in the first or second aspect, the drive IC has a plurality of output terminals for outputting the drive signal, and the plurality of output terminals are the plurality of connection contacts. The plurality of wirings included in the second wiring portion are connected to the plurality of output terminals, respectively.

  According to the present invention, since the drive IC is provided with a plurality of output terminals more than the plurality of connection contacts, the number of wirings for the connection of the wirings connecting the first and second connection terminals and the driving IC is the same. Since the allocation can be freely changed, it is easy to adjust the wiring resistances of the first and second connection terminals and the driving IC.

  A piezoelectric actuator device according to a fourth aspect of the present invention is characterized in that, in the first to third aspects, a plurality of wires included in the second wiring portion are connected to one second connection contact.

  According to the present invention, since no wiring other than the second connection contact is disposed in the vicinity of the second connection contact, it is easy to secure a space for forming an extra wiring in the base material. Therefore, it is possible to arrange a plurality of wires included in the second wiring portion while securing an arrangement space for other wires on the substrate.

  According to a fifth aspect of the invention, the piezoelectric actuator device according to the fourth aspect is characterized in that a plurality of wires included in the second wiring portion are connected to the plurality of output terminals, respectively.

  According to the present invention, since the plurality of output terminals of the drive IC are divided and configured, it is easy to connect the plurality of wirings included in the second wiring part.

  The piezoelectric actuator device according to a sixth aspect of the present invention is the piezoelectric actuator device according to the first aspect, wherein a plurality of wires included in the second wiring portion are connected to the plurality of output terminals, respectively, and are separated from each other. It is formed above and is connected to the second connection terminal.

  According to the present invention, the plurality of wirings included in the second wiring are arranged so as to extend from the driving IC to the second connection contact. Therefore, since there is no branch where a plurality of wirings are concentrated, it is easy to form the wirings.

  According to a seventh aspect of the present invention, in the first to sixth aspects, the plurality of wirings included in the second wiring portion have a width in a direction orthogonal to the extending direction of each of the first wirings. It is characterized in that it is equal to the width of the wiring included in the section, and further, the width of each other is also equal.

  According to this invention, the width of the plurality of wirings included in the second wiring part is equal to the width of the wirings included in the first wiring part. That is, since all the wiring widths on the base material are equal, the wiring is easy to form on the substrate.

  According to an eighth aspect of the present invention, in the first to seventh aspects, the drive IC includes a plurality of output terminals that output the drive signal, and a plurality of input contacts that are respectively connected to the plurality of output terminals. The base material has a power supply terminal connected to a power supply, and a power supply wiring connected to the power supply terminal and extending from the power supply terminal in a predetermined direction, and the plurality of input contacts are A first input contact and a first input contact connected to a portion of the power supply wiring that is further away from the power supply terminal than the first input contact, aligned in the extending direction of the power supply wiring. Two input contacts, the wiring included in the first wiring portion is connected to an output terminal connected to the first input contact, and the plurality of wirings included in the second wiring portion are 2 Connected to the output terminal connected to the input contact It is characterized in.

  The further away from the power source, the lower the voltage of the signal output from the output terminal through the input contact due to the voltage drop due to the power supply wiring, and the lower the voltage applied to the piezoelectric element. However, according to the present invention, the input contact connected to the plurality of wirings included in the second wiring part is located in a portion of the power supply wiring far from the power supply terminal compared to the input contact connected to the wiring included in the first wiring part. It is connected. Therefore, the electrical resistance from the power supply terminal to the second connection contact is different from the electrical resistance from the power supply terminal to the first connection contact of the wiring included in the first wiring part and the second wiring part as in the conventional case. Compared to the case where the numbers are the same. Thereby, the difference of the voltage respectively applied to the piezoelectric element connected to the 1st connection contact and the piezoelectric element connected to the 2nd connection contact can be made small.

  According to a ninth aspect of the present invention, in the first to eighth aspects, the piezoelectric actuator includes a first nozzle that discharges the first liquid and a second nozzle that discharges the second liquid. A piezoelectric actuator device used in the apparatus, wherein the piezoelectric element of the piezoelectric actuator has a first piezoelectric element that discharges liquid from the first nozzle and a liquid that discharges liquid from the second nozzle, and the first piezoelectric element A second piezoelectric element having a smaller capacitance than the first piezoelectric element, and a plurality of wirings included in the second wiring portion are connected to connection contacts for supplying the drive signal to the first piezoelectric element. It is characterized by being.

  According to the present invention, the first piezoelectric element requires more current than the second piezoelectric element in order to apply the same discharge pressure to the liquid as the second piezoelectric element. Therefore, a large amount of current can be supplied to the first piezoelectric element by connecting the second wiring and the first piezoelectric element.

  According to a tenth aspect of the present invention, in the ninth aspect, the first liquid is a pigment ink, and the second liquid is a dye ink.

  The present invention can also be applied to a liquid ejection device that ejects pigment ink and dye ink.

  According to the present invention, the second wiring portion has a portion where the number of wirings connecting the driving IC and the connection contact is larger than that of the first wiring portion. As a result, the wiring resistance connecting the second connection contact and the driving IC is smaller than the wiring resistance connecting the first connection contact and the driving IC. As a result, the difference between the rise and fall of the voltage of the piezoelectric element connected to the first connection contact and the piezoelectric element connected to the second connection contact can be suppressed as much as possible.

1 is a plan view schematically showing an ink jet printer according to an embodiment. 2 is a plan view of the inkjet head 3. FIG. It is the III-III sectional view taken on the line of FIG. It is the top view which looked at FPC from the bottom. It is a top view which shows the detail of FPC of FIG. It is a figure which shows the characteristic of the discharge speed of the nozzle from the voltage TrTf time-nozzle in an individual electrode. FIG. 6 is a voltage waveform for explaining the TrTf time of voltage, (a) is a voltage waveform at the output part of the drive IC, (b) is a voltage waveform at an individual electrode when supplied from one drive IC, (c ) Are voltage waveforms at the individual electrodes when supplied from two drive ICs. It is the top view which looked at FPC in the 1st modification from the lower part. It is the top view which looked at FPC in the 2nd modification from the lower part. It is the top view which looked at FPC in the 3rd modification from the lower part. It is the top view which looked at FPC in the 4th modification from the lower part. It is the top view which looked at FPC in the 5th modification from the lower part. It is sectional drawing of the inkjet head in a 9th modification.

  Hereinafter, embodiments of the present invention will be described. This embodiment is an example in which the present invention is applied to an inkjet printer having an inkjet head that ejects ink onto a recording sheet.

<Configuration of Inkjet Printer 1>
First, a schematic configuration of the ink jet printer according to the present embodiment will be described. As shown in FIG. 1, an inkjet printer 1 includes a carriage 2 configured to be reciprocally movable along a predetermined scanning direction (corresponding to the horizontal direction in FIG. 1), and an inkjet head 3 mounted on the carriage 2. , A transport mechanism 4 that transports the recording paper P in a paper feed direction orthogonal to the scanning direction, and a control unit 70 that controls the operation of the inkjet printer 1.

  The carriage 2 is configured to be reciprocally movable along two guide shafts 17 extending in parallel with the scanning direction. Further, an endless belt 18 is connected to the carriage 2, and when the endless belt 18 travels and is driven by the carriage drive motor 19, the carriage 2 moves in the direction opposite to the scanning direction as the endless belt 18 travels. To move to.

  An ink jet head 3 is mounted on the carriage 2. The inkjet head 3 has a plurality of nozzles 35 (see FIGS. 2 and 3) on the lower surface thereof (corresponding to the surface on the other side of the paper in FIG. 1).

  The transport mechanism 4 includes a paper feed roller 12 disposed on the upstream side in the paper feed direction from the inkjet head 3 and a paper discharge roller 13 disposed on the downstream side in the paper feed direction from the inkjet head 3. The paper feed roller 12 and the paper discharge roller 13 are rotationally driven by a paper feed motor 10 and a paper discharge motor 11, respectively. The transport mechanism 4 transports the recording paper P from above in FIG. 1 to the ink jet head 3 by the paper feed roller 12, and records the images and characters recorded by the ink jet head 3 by the paper discharge roller 13. The paper P is discharged downward in FIG.

<Configuration of inkjet head 3>
Next, the inkjet head 3 will be described. The inkjet head 3 has a nozzle row 35a that faces the recording paper P that is transported downward (hereinafter referred to as a paper feed direction) in FIG. is doing. The inkjet head 3 is directed toward the recording paper P from the nozzles 35 (corresponding to the first nozzle of the present invention) belonging to the nozzle array 35a and the nozzles 35 (corresponding to the second nozzle of the present invention) belonging to the nozzle array 35b. The ink supplied from an ink cartridge (not shown) is ejected.

  As shown in FIGS. 2 and 3, the inkjet head 3 is configured to apply pressure to the ink in the pressure chamber 34 and the flow path unit 30 in which the ink flow paths including the plurality of nozzle rows 35 a and 35 b and the pressure chamber 34 are formed. A piezoelectric actuator 31 to be applied and a flexible wiring board 45 (hereinafter referred to as FPC) covering the upper surface of the piezoelectric actuator 31 are provided.

  The plurality of nozzle rows 35a and 35b are arranged side by side in the scanning direction, and further include a plurality of nozzles 35 arranged in the paper feed direction. The nozzles 35 belonging to the plurality of nozzle arrays 35a eject black ink containing pigment color material, and the nozzles 35 belonging to the plurality of nozzle arrays 35b eject yellow ink, magenta ink and cyan ink containing dye color material. To do.

  The flow path unit 30 is configured by laminating a plurality of plates. The flow path unit 30 includes four ink supply ports 32 connected to four ink cartridges (not shown), and each ink. A manifold 33 connected to the supply port 32 and extending along the paper feed direction of FIG. 2 orthogonal to the scanning direction, a plurality of pressure chambers 34 communicating with each manifold 33, and a plurality of pressure chambers communicating with the plurality of pressure chambers 34, respectively. A nozzle 35 is formed. The plurality of pressure chambers 34 are arranged along the manifold 33 extending in the paper feeding direction, thereby forming the pressure chamber row 8 and the pressure chamber row 88.

  The two pressure chamber rows 8 constitute one pressure chamber group 7, and the same color ink is supplied to the plurality of pressure chambers 34 belonging to the pressure chamber group 7. The two pressure chamber rows 88 also constitute one pressure chamber group 77, and black ink is supplied to the plurality of pressure chambers 34 belonging to the pressure chamber group 77. The pressure chambers 34 belonging to the pressure chamber group 7 communicate with the nozzles 35 belonging to the nozzle row 35b, and the pressure chambers 34 belonging to the pressure chamber group 77 communicate with the nozzles 35 belonging to the nozzle row 35a. The nozzle row 35 a is constituted by four nozzle rows connected to the four pressure chamber rows 88, and the three nozzle rows 35 b are respectively constituted by two nozzle rows connected to the two pressure chamber rows 8.

  There is a wide space between the pressure chamber group 7 and the pressure chamber group 77, and there is also a wide space between the nozzle row 35a and the nozzle row 35b connected to these. Therefore, the surface on which the nozzles 35 are formed has a space between the nozzle row 35a and the nozzle row 35b. This space has a lip that divides the space defined by a cap (not shown) that covers the surface on which the nozzle 35 is formed into two during purging for forcibly discharging the ink in the nozzle 35 of the flow path unit 30. It is a contact area. Thus, the lip for partitioning the space is formed in the cap, so that the nozzle row 35a and the nozzle row 35b can be purged independently and separately. Further, since the space between the nozzle row 35a and the nozzle row 35b is wide, the black ink adheres to the color ink nozzles 35 when wiping along the paper feeding direction with a wiper extending in the scanning direction. Color mixing can be suppressed.

  Further, an FPC 45 having a shape elongated in the paper feeding direction is disposed on the upper surface of the piezoelectric actuator 31. The FPC 45 is connected to a control unit 70 (see FIG. 1) built in the printer 1. Thus, the inkjet head 3 and the control unit 70 are connected.

<Configuration of piezoelectric actuator 31>
Next, the piezoelectric actuator 31 will be described. The piezoelectric actuator 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 common electrode 142 disposed between the diaphragm 40 and the piezoelectric layer 41, a common electrode contact 242 formed on the upper surface of the piezoelectric layer 41, The piezoelectric layer 41 has a conductive portion 243 that penetrates from the upper surface to the lower surface and conducts the common electrode 142 and the common electrode contact 242.

  The diaphragm 40 is a substantially rectangular metal plate in plan view, and is made of, for example, an iron-based alloy such as stainless steel, a copper-based alloy, a nickel-based alloy, or a titanium-based alloy. The diaphragm 40 is joined to the upper surface of the uppermost plate of the flow path unit 30 in a state of being disposed so as to cover the plurality of pressure chambers 34.

  The piezoelectric layer 41 is made of a piezoelectric material mainly composed of lead zirconate titanate (synonymous with PZT), which is a solid solution of lead titanate and lead zirconate and is a ferroelectric substance. As shown in FIG. 2, the piezoelectric layer 41 is continuously formed across the plurality of pressure chambers 34 on the upper surface of the vibration plate 40.

  The plurality of individual electrodes 42 are respectively disposed in regions on the upper surface of the piezoelectric layer 41 facing the plurality of pressure chambers 34. Each individual electrode 42 has a substantially oval planar shape that is slightly smaller than the pressure chamber 34, and faces the central portion of the pressure chamber 34. Further, a plurality of contacts 43 (corresponding to the conduction point of the present invention) connected to the FPC 45 are respectively drawn out from the ends of the plurality of individual electrodes 42 on the side opposite to the scanning direction. The plurality of individual electrodes 42 are electrically connected to the two drive ICs 46a and 46b via bumps 47 and wirings 48 (see FIG. 4) of the FPC 45.

  The common electrode 142 has a shape facing all of the plurality of pressure chambers 34, and is further connected to the bumps 57 of the FPC 45 through the common electrode contact 242. Furthermore, the common electrode 142 is connected to the ground through the common wiring 59 (see FIG. 4) of the FPC 45, and a ground potential is applied.

  The piezoelectric layer 41 has a plurality of active portions 41a (corresponding to the piezoelectric element of the present invention) sandwiched between the plurality of individual electrodes 42 and the common electrode 142, and is polarized upward. When a potential difference (synonymous with voltage) occurs between the individual electrode 42 and the common electrode 142, piezoelectric deformation (synonymous with piezoelectric distortion) occurs in the active part 41a, and this deformation causes the active part 41a to face the active part 41a. A pressure is applied to the ink in the pressure chamber 34.

  Next, the operation of the piezoelectric actuator 31 during ink ejection will be described. In each active part 41a sandwiched between the individual electrode 42 and the diaphragm 40 as a common electrode, the electric potential of the individual electrode 42 is the same ground potential as the common electrode 142 in a state where no charge is stored. . At this time, an electric field does not act on the active portion 41a, and no piezoelectric distortion occurs in the active portion 41a.

  From this state, when the drive IC 46 applies a drive potential to a certain active portion 41a, the potential of the individual electrode 42 becomes higher than the diaphragm 40 having the ground potential. Therefore, a predetermined voltage is applied between the individual electrode 42 and the common electrode 142 sandwiching the active portion 41a, and a downward electric field acts on the active portion 41a.

  Since the direction of the electric field is parallel to the polarization direction of the piezoelectric layer 41, the active portion 41a contracts in a scanning direction (also referred to as a surface direction) orthogonal to the upward direction and the downward direction. Here, since the lower vibration plate 40 of the piezoelectric layer 41 is fixed to the uppermost plate of the flow path unit 30, the piezoelectric layer 41 positioned on the upper surface of the vibration plate 40 contracts in the plane direction. At the same time, the portion of the diaphragm 40 covering the pressure chamber 34 is deformed so as to protrude toward the pressure chamber 34 (generally referred to as unimorph deformation). At this time, since the volume in the pressure chamber 34 decreases, the ink pressure in the pressure chamber 34 rises, and ink is ejected from the nozzles 35 communicating with the pressure chamber 34.

  Further, when the potential of the individual electrode 42 becomes the ground potential again, the electric field no longer acts on the active portion 41a, so that the deformed state of the active portion 41a is eliminated, and the diaphragm 40 is in the original state (the flow path unit 30). It returns to the same meaning as the state parallel to the plate that constitutes.

<Configuration of FPC 45>
Next, the FPC 45 will be described with reference to FIGS. 4 and 5 show only a part of the wiring, and the illustration of most of the wirings is omitted.

  As shown in FIG. 4, the FPC 45 has a substrate 49 (corresponding to the base material of the present invention), two drive ICs 46 a and 46 b arranged at both ends of the base material 49 in the paper feed direction, and a surface of the substrate 49. A plurality of formed bumps 47 (corresponding to connection contacts of the present invention), two drive ICs 46 a and 46 b, and a plurality of wirings 48 a and 48 b respectively connected to the plurality of bumps 47 are provided.

  The FPC 45 includes individual input terminals 50a and 50b for individual electrodes connected to the control unit 70, individual wirings 51a and 51b for connecting the individual input terminals 50a and 50b and the two drive ICs 46a and 46b, respectively, and a power source. Connected power supply terminals 52a and 52b, power supply wirings 54a and 54b connected to the power supply terminals 52a and 52b, ground terminals 53a and 53b connected to the ground through the control unit 70, and grounds connected to the ground terminals 53a and 53b. Wiring 55a, 55b. The FPC 45 is disposed at both ends of the substrate 49, and has common electrode wirings 59 that are electrically connected to the bumps 57, and common electrode terminals 61 a and 61 b that are connected to the common electrode wirings 59. Further, the FPC 45 includes a first wiring portion 48a (corresponding to the first wiring portion of the present invention) and a second wiring portion 48b (corresponding to the second wiring portion of the present invention).

  The plurality of bumps 47 are arranged at predetermined intervals in the paper feed direction corresponding to the rows of the contacts 43 of the piezoelectric actuator 31 and the rows are arranged in a plurality of rows in the scanning direction.

  As shown in FIG. 5, the drive IC 46 a has a plurality of output terminals 80. Each of the plurality of output terminals 80 outputs a drive signal for applying a voltage to each of the plurality of individual electrodes 42. The power supply lines 54a and 54b are connected to the drive ICs 46a and 46b, and the ground lines 55a and 55b are also connected to the drive ICs 46a and 46b.

  The drive IC 46a has a plurality of input contacts 90 for input connected to the power supply wiring 54a and a plurality of ground contacts 98 connected to the ground wiring 55a. The plurality of input contacts 90 and the plurality of ground contacts 98 are arranged side by side in the paper feed direction together with the plurality of output terminals, and the input contacts 90, ground contacts 98, and output terminals 80 arranged in a line in the paper feed direction. Are connected. The plurality of input contacts 90 are arranged side by side in the scanning direction in which the power supply wiring 54a extends, and are separated from the power contact 52a from the input contact 91 (corresponding to the first input contact of the present invention) and the input contact 91. Input contacts 95 and 96 (corresponding to the second input contact of the present invention) connected to the site of the power supply wiring 54a are included. The input contact 91 is electrically connected to the output terminal 81 of the drive IC 46a. The input contacts 95 and 96 are electrically connected to the output terminals 85 and 86 of the drive IC 46a.

  The plurality of bumps 47 are arranged in the paper feed direction to form bump rows 99a and 99b (corresponding to the connection contact row of the present invention), and the bump row 99 includes the bump 47a (the first connection contact of the present invention). And a bump 47b (corresponding to the second connection contact of the present invention). The bump 47b is disposed in a region closer to the center line C in the paper feed direction of the substrate 47 than the bump 47a.

  As shown in FIG. 5, the first wiring portion 48a includes a wiring 71 (corresponding to a wiring included in the first wiring portion of the present invention) arranged on the substrate 49, and the wiring 71 is an output of the drive IC 46a. The terminal 81 and the bump 47a are connected. The second wiring part 48b includes wirings 75 and 76 (corresponding to wirings included in the second wiring part of the present invention) arranged on the substrate 49. The wiring 75 is connected to the output terminal 85 of the driving IC 46a and the bump 47b, and the wiring 76 is connected to the output terminal 81 of the driving IC 46a and the bump 47b.

  Note that the paper feed direction of this embodiment is an example of the arrangement direction of the present invention.

<Discharge characteristics>
By the way, the ejection characteristic of the ink ejected from the nozzle 35 is the time (hereinafter referred to as TrTf time) required for the voltage rise and fall between the individual electrode 42 and the common electrode 142 sandwiching the active portion 41a from the drive IC 46. It depends. This discharge characteristic will be described with reference to FIG. The TrTf time is a value that summarizes the time required for the voltage rise and the time required for the fall. The larger the value, the longer the time required for the rise / fall, and the smaller the value, the shorter the time required for the rise / fall. It is shown that. For example, as shown in FIG. 6, when the TrTf time is small, the ink ejection speed from the nozzle 35 is high, and when the TrTf time is large, the ink ejection speed from the nozzle 35 is slow. Further, when the TrTf time becomes smaller than a certain value, the ink discharge speed from the nozzle 35 becomes a saturated speed without being further increased.

  Here, since the plurality of active portions 41a have capacitance, they act as capacitors, and the driving IC 46 and the active portion 41a are connected by a wiring 48, and this wiring 48 has a wiring resistance R2. . Then, a CR circuit exists equivalently from the driving IC 46 to the active part 41a, and the time constant of the CR circuit affects the TrTf time of the voltage at the individual electrode 42. The time constant of the CR circuit is proportional to the capacitance of the active part 41a and the wiring resistance R2 of the wiring 48 connecting the driving IC 46 and the active part 41a. As described above, the plurality of active parts 41a When there is a variation in capacitance among the wirings, or when there is a variation in the wiring resistance R2 between the wirings 48 connecting the driving IC 46 and the plurality of active portions 41a, the TrTf time of the voltage at the individual electrode 42 Variations occur, resulting in non-uniform operations among the plurality of active portions 41a.

  Since the bump 47b in the bump row 99a is arranged farther from the driving IC 46a than the bump 47a, the wiring connected to the bump 47b is longer than the wiring connected to the bump 47a. In particular, the bump 47a closest to the drive IC 46a and the bump 47b have a very large difference in distance from the drive IC 46a. The wiring connecting the bump 47a and the drive IC 46a, and the wiring connecting the bump 47b and the drive IC 46a are very different. The difference in length increases. Therefore, the wiring resistance of the wiring connecting the bump 47a and the driving IC 46a and the wiring connecting the bump 47b and the driving IC 46a are greatly different, and the voltage TrTf time at the individual electrode 42 varies.

  Therefore, the second wiring part 48b connected to the bump 47b is connected to the two wirings 75 and 76, and is configured to have a larger number of wirings than the first wiring part 48a connected to the bump 47a. Yes. The two wirings 75 and 76 have the same width as the wiring 71.

  Next, the voltage TrTf time in the individual electrode 42 that is electrically connected to the bump 47b will be described.

  When a voltage is applied from the drive IC 46 to the individual electrode 42, as shown in FIG. 7A, the voltage at the output portion of the drive IC 46 rises in a pulse shape at a substantially right angle. When the application of voltage from the drive IC 46 to the individual electrode 42 is stopped, the voltage at the output portion of the drive IC 46 falls in a pulse shape at a substantially right angle.

  At this time, for example, if a voltage is applied to the individual electrode 42 connected to only one wiring with respect to the individual electrode 42 connected to the bump 47b to which the two wirings 75 and 76 are connected, FIG. As shown in b), the voltage of the individual electrode 42 does not rise or fall as quickly as the output part of the driving IC 46a, but rises and falls over a long time. On the other hand, when a voltage is applied from the driving IC 46a to the individual electrode to which the two wirings 75 and 76 are connected, as shown in FIG. 7C, the voltage of the individual electrode 42 is as shown in FIG. It rises and falls in a shorter time than b).

  Since the drive IC 46a and the bump 47b are connected to the two wirings 75 and 76, the electrical resistance between the drive IC 46a and the bump 47b is smaller than that of the drive IC 46a and the bump 47a connected by the single wiring 71. The wiring resistance R2 corresponding to is reduced. This is because the time constant of the CR circuit, which is an equivalent circuit, is reduced. From another viewpoint, since current is supplied from the two wirings 75 and 76, substantially the same effect as that supplied and discharged from the two drive ICs can be obtained. Therefore, the charging current supply rate can be increased and the discharge current discharging rate can be increased. From these, the TrTf time of the voltage at the individual electrode 42 corresponding to the active part 41a to which the two wirings 75 and 76 are connected can be shortened.

  Thereby, the operation | movement between several active part 41a is made uniform by connecting two wiring 75,76 with respect to the active part 41a connected to the bump 47b among several active parts 41a. be able to. Thereby, it is possible to suppress variations in the ejection speed of ink from the nozzles 35 and to suppress variations in ejection characteristics between the nozzles.

  Further, since the drive IC 46a is provided with a plurality of output terminals 80 more than the plurality of bumps 47, when the output terminals 80 and the bumps 47 are connected to each other by using one wiring, the output terminals 80 are left over. End up. Therefore, the surplus output terminal 80 is connected to the bump 47b via the wirings 75 and 76, so that the resistance of the wiring between the bump 47b and the driving IC 46a can be lowered.

  Since the number of the output terminals 80 of the driving IC 46a is larger than that of the bump 47, the driving IC 46a is longer in the scanning direction than the conventional driving IC. However, the conventional substrate has a space between the drive IC and the common electrode wiring in the scanning direction, but almost no wiring or the like is formed in this space. Therefore, even if the driving IC is increased in the scanning direction by increasing the number of output terminals, there is no problem that the wiring cannot be formed if the driving IC is long enough to fill the space. Therefore, it is possible to reduce the resistance of the wiring between the driving IC and the bump while effectively utilizing the space of the substrate.

<Method for producing FPC45>
Here, a method for manufacturing the FPC 45 will be briefly described. First, a mask process is performed on the substrate 49 with a resist. Next, a through hole is formed in the resist by etching or the like. The through hole has the same shape as the wiring pattern formed on the substrate 49. Next, a conductive material to be a wiring is applied on the resist. At this time, the conductive material is applied so that the conductive material fills the through hole formed in the resist. Then, the conductive material is cured, and then the resist is removed.

  The two wirings 75 and 76 have a length (hereinafter referred to as a width) perpendicular to the extending direction equal to the width of the wiring 71. Therefore, when the FPC 45 is manufactured by the above manufacturing method, the widths of the through holes for forming the wirings 75 and 76 formed in the resist and the wiring 71 are equal. Therefore, the fluidity of the conductive material, which is the wiring material, flowing into the through hole becomes uniform, and it becomes easy to accurately form the wiring on the substrate.

  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.

<First modification>
In the present embodiment, the second wiring portion 48b is configured by the two wirings 75 and 76, but the present invention is not limited to this configuration. For example, it may be configured as an FPC 145 shown in FIG. The second wiring portion 148b is configured to include one wiring 177 connected to the output terminal 185 of the driving IC 46a and two wirings 175 and 176 branched from the wiring 177. These two wirings 175 and 176 may be connected to the bump 147b, respectively.

  According to this configuration, the effect of the present invention can be obtained even when the number of output terminals of the drive IC 46a is the same as the number of bumps. Therefore, it is possible to suppress an increase in size of the drive IC and to reduce the cost of the drive IC.

<Second modification>
Further, the present invention may be configured as, for example, an FPC 245 shown in FIG. The second wiring portion 248b includes wirings 275 and 276 connected to the two output terminals 285 and 286, respectively, and one wiring 277 to which these wirings 275 and 276 are connected. The wiring 277 is connected to the bump 247b.

  According to the present invention, the second wiring 248b can be configured when there is a space for arranging the two wirings 275 and 276 only in the vicinity of the drive IC 46a.

<Third modification>
Further, the present invention may be configured as an FPC 345 shown in FIG. The second wiring portion 348b is connected so as to branch from one wiring 277 and one wiring 277 connected to the output terminals 385 and 386 of the driving IC 46a, one wiring 277 connected to the wirings 275 and 276, respectively. Wirings 278 and 279 are provided. The wirings 278 and 279 are connected to the bumps 347b, respectively.

  According to the present invention, it is possible to arrange the wirings 275 and 276 included in the second wiring part 348b at various places by utilizing the space that is free on the substrate. Thereby, the wiring resistance of the 2nd wiring part 348b can be made low.

<Fourth modification>
Further, the present invention may be configured as an FPC 445 shown in FIG. The second wiring portion 448b includes a wiring 377 connected to the output terminal 485 of the driving IC 46a, two wirings 375 and 376 connected to the wiring 377, and one wiring 378 connected to the two wirings 375 and 376. And. The wiring 378 is connected to the bump 447b.

  According to the present invention, it is possible to arrange the wirings 375 and 376 included in the second wiring part 448b at various locations by utilizing the space that is free on the substrate. Thereby, the wiring resistance of the 2nd wiring part 448b can be made low.

<Fifth modification>
Furthermore, the present invention may be configured as an FPC 555 shown in FIG. The first wiring portion 548a has two wirings 378 and 379, and the two wirings 378 and 379 are connected to the output terminals 588 and 589 of the driving IC 46a and the bump 547a, respectively. The second wiring portion 448b includes three wirings 375, 376, and 377. The three wirings 375, 376, and 377 are respectively connected to the output terminals 585, 586, and 587 and the bump 547b of the driving IC 46a. It is connected.

  According to the present invention, like the bumps 547a and 547b, by increasing the number of wirings as the distance from the driving IC 46a increases, even if the number of bumps increases in the paper feed direction, the bumps 547a and 547b The difference in wiring resistance between the first wiring portion 548a and the second wiring portion 548b to be connected can be reduced.

<Sixth modification>
In the fifth modification, the first wiring portion 548a has two wires and the second wiring portion 448b has three wires. For example, the first wiring portion has one wire. It may be configured so that the second wiring portion includes the one including three wirings and the one including four wirings.

  According to this invention, it can comprise so that the difference of the wiring resistance of the wiring connected to each bump may be made still smaller.

<Seventh modification>
In this embodiment, the capacitance of the active layer 31a for ejecting black, cyan, yellow, and magenta inks is equal, but the application of the present invention is not limited to this. For example, black ink containing pigment color material and cyan, yellow, and magenta color ink containing dye color material have different viscosities at room temperature. The pressure chamber may be configured larger than the pressure chamber for color ink. In such a configuration, the active portion that applies pressure to the ink in the pressure chamber that communicates with the nozzle that discharges black ink is more active than the active portion that applies pressure to the ink in the pressure chamber that communicates with the nozzle that discharges color ink. Also, the area is large. In other words, the individual electrode for black ink has a larger area than the individual electrode for color ink. Therefore, the active layer for black ink has a larger capacitance than the active layer for color ink. For this reason, the black ink individual electrode and the driving IC are connected by a plurality of wires so that a larger amount of current flows in the black ink active layer than in the color ink active layer. You may comprise so that an electrode and drive IC may be connected by one wiring.

  According to the present invention, more current can be supplied to the individual electrode for black ink.

<Eighth modification>
In the seventh modification, the individual electrode for black ink and the drive IC are connected by a plurality of wires, and the individual electrode for color ink and the drive IC are connected by a single wire. However, it is not limited to this. For example, the individual ink for cyan ink may be connected to the drive IC using a plurality of wirings, and the other individual electrode for ink may be connected to the drive IC using one wiring. In addition, the combination of the one connected to the driving IC using a plurality of wirings and the one connected to the driving IC using one wiring are changed depending on the configuration of the inkjet head to which the FPC is connected. May be configured.

<Ninth modification>
In addition, in the present embodiment, the adjacent active portions 41a of the piezoelectric actuator 31 are connected via the surrounding piezoelectric layer 41. However, as shown in FIG. Each of the piezoelectric layers 141 may be disposed separately from each other.

<10th modification>
In the present embodiment, two drive ICs 46a and 46b are provided. However, one drive IC may be provided. Furthermore, the present invention can be applied to a device provided with three or more drive ICs.

<Eleventh modification>
Further, the width of two wirings connected to one active part may be narrower than the width of one wiring connected to one active part. According to this, the difference between the wiring resistance of two wirings connected to one active part and the wiring resistance of one wiring can be made smaller. Furthermore, since the wiring arrangement space on the substrate 49 is secured, the wiring density can be reduced, and the wiring board can be easily manufactured.

  As described above, in the embodiments described above and modifications thereof, the present invention is applied to a piezoelectric actuator having a plurality of drive ICs for an ink jet head that records an image or the like by ejecting ink onto a recording sheet. The application target is not limited to such a piezoelectric actuator for an ink jet head, and for example, it can also be used for a liquid ejecting apparatus capable of ejecting a conductive material that is a wiring material of a wiring board. The present invention can also be applied to piezoelectric actuators used for various purposes in addition to the liquid ejection device.

1 Printer 31 Piezoelectric Actuator 41a Active Part 43 Conduction Point 45 FPC
46a, 46b Drive IC
47a, 47b Bump 48a First wiring portion 48b Second wiring portion 49 Substrate 71, 75, 76 Wiring 81, 85, 81 Output terminal 99a, 99b Bump row

Claims (10)

A piezoelectric actuator having a plurality of piezoelectric elements and a plurality of input conduction points that respectively conduct to the piezoelectric elements;
A substrate, a drive IC disposed on the substrate and outputting a drive signal for driving the piezoelectric actuator, and a plurality of substrates disposed on the substrate, connected to the drive IC and connected to the plurality of conduction points A wiring board having connection contacts of
With
The substrate is
A plurality of connection contacts arranged in an array direction away from the drive IC;
A first wiring portion including a wiring for connecting the first connection contact belonging to the connection contact row and the drive IC;
A second wiring portion that belongs to the connection contact row and includes a second connection contact that is farther from the drive IC than the first connection contact in the arrangement direction, and a wiring that connects the drive IC;
Have
The piezoelectric actuator device according to claim 1, wherein at least a part of the second wiring part includes a plurality of wirings larger than the number of wirings included in the first wiring part.   2. The piezoelectric actuator device according to claim 1, wherein the first wiring portion has one wiring for connecting the first connection contact and the driving IC. The drive IC has a plurality of output terminals for outputting the drive signal,
The plurality of output terminals are provided more than the plurality of connection contacts,
3. The piezoelectric actuator device according to claim 1, wherein a plurality of wirings included in the second wiring portion are connected to the plurality of output terminals, respectively.   The piezoelectric actuator device according to claim 1, wherein a plurality of wirings included in the second wiring part are connected to one second connection contact.   5. The piezoelectric actuator device according to claim 4, wherein a plurality of wires included in the second wiring portion are connected to the plurality of output terminals, respectively.   A plurality of wires included in the second wiring portion are connected to the plurality of output terminals, respectively, are formed on the base material in a state of being separated from each other, and are connected to the second connection terminals. The piezoelectric actuator device according to claim 1. The plurality of wirings included in the second wiring part have the same width in the direction orthogonal to the direction in which each of the wirings extends, and the widths of the wirings included in the first wiring part are also equal. The piezoelectric actuator device according to any one of claims 1 to 6.
The drive IC has a plurality of output terminals for outputting the drive signal, and a plurality of input contacts respectively connected to the plurality of output terminals,
The base material has a power supply terminal connected to a power supply, and a power supply wiring connected to the power supply terminal and extending in a predetermined direction from the power supply terminal,
The plurality of input contacts are connected to the power supply line side by side in the direction in which the power supply line extends, and further, the first input contact and the power supply line further away from the power supply terminal than the first input contact And a second input contact connected to the site of
The wiring included in the first wiring portion is connected to an output terminal connected to the first input contact,
The piezoelectric actuator device according to claim 1, wherein the plurality of wirings included in the second wiring part are connected to an output terminal connected to the second input contact. The piezoelectric actuator is a piezoelectric actuator device used in a liquid ejection device including a first nozzle that ejects a first liquid and a second nozzle that ejects a second liquid,
The piezoelectric element of the piezoelectric actuator has a first piezoelectric element that discharges liquid from the first nozzle and a second piezoelectric element that discharges liquid from the second nozzle and has a smaller capacitance than the first piezoelectric element. Elements included,
The plurality of wirings included in the second wiring part are connected to connection contacts for supplying the drive signal to the first piezoelectric element. Piezoelectric actuator device.   The piezoelectric actuator device according to claim 9, wherein the first liquid is pigment ink, and the second liquid is dye ink.

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