JP2010214772A - Drive unit for liquid jetting device and method for detecting wiring state of drive unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a drive unit for a liquid ejection device that easily detects the connection state of the area connecting substrates in wiring provided over the two connected substrates, and to provide a method for detecting the wiring state thereof. <P>SOLUTION: In a piezoelectric actuator 12, two electrostatic capacitors CA and CB independent of an activating section 40 are provided in a certain area between each first low potential bias line 31 and a lower constant potential electrode 47 and in a certain area between each first high potential bias line 33 and an upper constant potential electrode 46. The open-side terminals of the third low potential wiring 84 and third high potential wiring 87 form: input terminals for potentials used to bias the lower constant potential electrode 47 and upper constant potential electrode 46 when a liquid is jetted; and measurement terminals for detecting the connection state of the wiring from an impedance measurement value between both the terminals. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a drive unit of a liquid ejection apparatus such as an ink jet printer apparatus and a wiring state detection method thereof, and more particularly to a configuration and method capable of detecting a connection state at a connection point of wirings across two substrates.

  As an example of a liquid ejection apparatus, an ink jet printer apparatus including a liquid ejection head that ejects liquid (ink) from a nozzle hole to a recording medium is known. The liquid discharge head provided in the printer apparatus includes a flow path unit in which a plurality of channels connecting the pressure chamber and the nozzle hole are formed, and a drive unit that applies discharge pressure to the ink in the pressure chamber. The liquid discharge head distributes the ink supplied from the tank to a plurality of pressure chambers, and applies a pulsed pressure to one or a plurality of pressure chambers from among all the pressure chambers. As a result, the liquid is ejected from the nozzle hole communicating with the pressure chamber to which the pressure is applied, and is adhered to the recording medium to form an image. Here, as an example of a drive unit that applies pressure to the ink in the pressure chamber, there is one in which a piezoelectric actuator is connected to a flexible substrate on which a drive circuit is mounted.

  For example, as disclosed in Patent Document 1, the piezoelectric actuator includes an individual electrode arranged individually facing each pressure chamber, a common electrode formed across a plurality of pressure chambers, and the individual electrode and the common electrode. A plurality of piezoelectric layers made of piezoelectric ceramics sandwiched between two layers are stacked. And it joins to a flow path unit on both sides of an insulating layer so that the pressure chamber opened on the upper surface of a flow path unit may be covered from upper direction.

  In addition, the flexible substrate connected to the piezoelectric actuator is generally expensive because the wiring structure between the drive circuit and the piezoelectric actuator cannot be a general-purpose product, and it is necessary to use one that matches the specifications of the piezoelectric actuator. It tends to be. Therefore, in Patent Document 2, the flexible substrate is divided into two, and is composed of a COF (Chip On Film) connected to the piezoelectric actuator by mounting a drive circuit, and a general-purpose FPC (Flexible Print Cable) extending from the COF to the printer main body side. It is disclosed.

JP 2008-195047 A JP 2007-196404 A

  In recent years, unlike the above-described ones, piezoelectric actuators having two types of common electrodes, a low potential common electrode and a high potential common electrode, have been proposed in addition to individual electrodes. A low potential wiring and a high potential wiring are provided to bias the potential to each of the potential common electrode and the high potential common electrode.

  In addition, each of the low-potential wiring and the high-potential wiring is divided into two in order to apply the low potential and the high potential as uniformly as possible to all the low potential common electrodes and the high potential common electrodes in the piezoelectric actuator. It is conceivable to form them at both ends of the flexible substrate and connect them to the low potential common electrode and the high potential common electrode at both ends of the piezoelectric actuator. In this case, the low-potential wiring and the high-potential wiring may be configured to branch from one to two on the FPC and to provide two on the COF corresponding to this branch. That is, two low potential wirings (first low potential wiring) and two high potential wirings (first high potential wiring) are formed in the COF, and two low potential wirings connected to these are formed in the FPC. A wiring (second low-potential wiring) and two high-potential wirings (second high-potential wiring) are formed. Further, in the FPC, a low-potential wiring (third wiring) that combines these two low-potential wirings into one. Low potential wiring), and similarly, a high potential wiring (third high potential wiring) obtained by joining two high potential wirings into one. This suppresses the influence of voltage drop at the low potential common electrode and the high potential common electrode, and in the entire area of the piezoelectric actuator, the low potential common electrode and the high potential common electrode respectively have substantially uniform low potential and high potential. Can be granted.

  Here, such a configuration has an advantage that the potential to each common electrode can be made uniform as described above, while the low potential wiring and the high potential wiring on the COF and the low potential wiring on the FPC and the high potential wiring. It is difficult to detect when there is a defect in each connection point with the potential wiring. For example, since the two low potential wirings on the COF side are conducted through the low potential common electrode, if the two low potential wirings on the FPC side are not merged, between the two low potential wirings on the FPC side A closed circuit is formed by connecting a voltmeter to. Therefore, if the measured value with the voltmeter is less than a predetermined value, it can be determined that the connection location between the COF and the FPC is properly connected, and if it is greater than the predetermined value, it can be determined that the connection location is disconnected. However, in the configuration in which the two low potential wirings on the FPC side are joined, a closed circuit cannot be formed by interposing a voltmeter as described above. The deficiency cannot be detected. The same can be said for detecting a defect in the connection portion between the COF and the FPC for the high potential wiring.

  Although it is conceivable to provide a terminal for connecting a voltmeter by drawing a separate wiring from two low-potential wirings (or high-potential wirings) on the FPC. It is retrograde and is not preferable. Such a situation is not limited to the ink jet printer apparatus, and the same applies to all liquid ejecting apparatuses including a drive unit having the same configuration.

  Accordingly, the present invention provides a drive unit of a liquid ejection device that can easily detect a connection state of a connection portion between substrates for a wiring provided across two connected substrates, and a wiring state detection of the drive unit. And to provide a method.

  In the drive unit wiring state detection method according to the present invention, two first low potential electrodes connected to the low potential electrode are connected to an actuator in which a low potential electrode, a high potential electrode, and a drive electrode are stacked with a piezoelectric layer interposed therebetween. A first sheet base material having a potential wiring and two first high potential wirings connected to the high potential electrode is connected to the first sheet base material, and further connected to the first low potential wirings. A second sheet substrate having two second low-potential wirings and two second high-potential wirings connected to each first high-potential wiring is connected, and the two second low-potential lines are connected The wiring and the two second high-potential wirings merge on the second sheet base material to form a third low-potential wiring and a third high-potential wiring, respectively. A wiring state detection method for a unit, comprising: the third low potential wiring included in the drive unit; A measuring instrument connected between the third high potential wiring and obtaining an impedance measurement value between the two wirings; between the first low potential wiring and the second low potential wiring; and the first A reference impedance that is an impedance between the third low-potential wiring and the third high-potential wiring when the high-potential wiring and the second high-potential wiring are both electrically connected. And comparing the measured impedance values.

  The drive unit of the liquid discharge apparatus according to the present invention is provided corresponding to a pressure chamber to which a pressure for discharging the liquid from the nozzle hole is applied, and is biased to a low potential electrode biased to a low potential and a high potential. A high-potential electrode, and a drive electrode to which a drive potential that changes with time is applied, an actuator having an active portion stacked in this order across a piezoelectric layer, and two first electrodes connected to the low-potential electrode 1 low-potential wiring and two first high-potential wirings connected to the high-potential electrode, connected to the first sheet base material connected to the actuator, and to each first low-potential wiring Two second low potential wires, two second high potential wires connected to each of the first high potential wires, a third low potential wire formed by joining the two second low potential wires, and A third high formed by the joining of the two second high potential wires. And a second sheet base material connected to the first sheet base material, in the actuator, in the middle of the first low potential wiring to the low potential electrode, Two capacitances independent of the active portion are formed between the first high potential wiring and the portion extending to the high potential electrode, and the third low potential wiring and the third high potential wiring are formed. Each open-side terminal of the potential wiring forms an input terminal for biasing the low-potential electrode and the high-potential electrode when the liquid is discharged, and the first low-potential wiring is determined based on the impedance measurement value via the capacitance. And a measurement terminal for detecting a connection state between the first high potential wiring and the second low potential wiring and the second high potential wiring.

  By adopting such a configuration, the first low potential wiring and the first high potential wiring are connected via the capacitance in the piezoelectric actuator, so that the open side of the third low potential wiring and the third high potential wiring A closed circuit can be formed by connecting an impedance measuring device between the terminals. Therefore, the connection portion of the low potential wiring and the high potential wiring provided across the first sheet base and the second sheet base, that is, the first low potential wiring and the first high potential wiring on the first sheet base It is possible to detect whether or not the connection portion between the second low potential wiring and the second high potential wiring on the second sheet base material is properly connected.

  ADVANTAGE OF THE INVENTION According to this invention, about the wiring provided ranging over two board | substrates connected, the drive unit of the liquid discharge apparatus which can detect the connection state of the connection location between board | substrates easily, and the wiring state of this drive unit And a detection method.

FIG. 2 is a schematic plan view illustrating a main part of a printer device that is a liquid ejection device. FIG. 3 is an exploded perspective view illustrating a configuration of a liquid discharge head provided in the printer device. FIG. 3 is a cross-sectional view showing a configuration when the head main body in a state in which the flow path unit and the piezoelectric actuator are joined is cut along a line III-III in FIG. 2 (a line along a nozzle row direction to be described later). FIG. 4 is a cross-sectional view showing a configuration when the head main body in a state where the flow path unit and the piezoelectric actuator are joined is cut along the line IV-IV in FIG. 2 (that is, a line along the nozzle row direction). It is a top view of a piezoelectric actuator. It is drawing which shows the structure of the flexible substrate 13 shown in FIG. 2, (a) is a schematic bottom view of COF, (b) has shown the schematic plan view of FPC. It is drawing which shows the equivalent circuit of the drive unit at the time of detecting a wiring state. It is a flowchart which shows the procedure which detects the wiring state of a drive unit. It is sectional drawing which shows a structure when the head main body of the drive unit provided with the structure different from what was mentioned above is cut | disconnected by the line along a nozzle row direction. 10 is a diagram illustrating an equivalent circuit of the drive unit when detecting a wiring state in the drive unit illustrated in FIG. 9. Furthermore, it is sectional drawing which shows a structure when the head main body of the drive unit provided with a different structure is cut | disconnected by the line along the nozzle row direction. FIG. 12 is a diagram showing an equivalent circuit of the drive unit when detecting a wiring state in the drive unit shown in FIG. 11.

  Hereinafter, the case of applying the liquid ejection apparatus and the manufacturing method thereof according to the embodiment of the present invention to an inkjet printer apparatus (hereinafter referred to as “printer apparatus”) which is an example of the liquid ejection apparatus will be described as an example. This will be described with reference to FIG. However, it should be noted that the present invention is not limited to application to a printer apparatus, but can be applied to all liquid ejection apparatuses that eject liquid other than ink.

[Overall configuration of printer device]
FIG. 1 is a schematic plan view showing a main part of a printer apparatus 100 as a liquid ejection apparatus. As shown in FIG. 1, the printer apparatus 100 includes a pair of guide rails 102 and 103 extending in the left-right direction. The guide rails 102 and 103 can slide the liquid supply unit 104 in the scanning direction. It is supported by. A pair of pulleys 105 and 106 are provided near the left and right ends of the guide rail 103, and the liquid supply unit 104 is joined to a timing belt 107 wound around the pulleys 105 and 106. One pulley 106 is provided with a motor (not shown) that drives forward and reverse rotation, and when the pulley 106 is driven forward and reverse, the timing belt 107 can reciprocate leftward and rightward. Accordingly, the liquid supply unit 104 is reciprocally scanned in the left-right direction along the guide rails 102 and 103.

  Four ink cartridges 108 are detachably mounted on the printer device 100 for replacement. The liquid supply unit 104 includes four flexible ink supply tubes 109 for supplying four colored inks (for example, black, cyan, magenta, and yellow) from these ink cartridges 108, respectively. It is connected. A liquid discharge head 2 (see FIG. 2) is mounted below the liquid supply unit 104, and a recording medium (for example, recording paper) that is conveyed in a direction perpendicular to the scanning direction (paper feeding direction) below the liquid discharging head 2 (see FIG. 2). Ink (liquid) is ejected from the liquid ejection head 2 toward the surface, and an image can be formed on the recording medium.

[Schematic configuration of liquid discharge head]
FIG. 2 is an exploded perspective view showing the configuration of the liquid ejection head 2 provided in the printer apparatus 100. As shown in FIG. 2, the liquid discharge head 2 includes a head body 15 formed by joining the piezoelectric actuator 12 to the flow path unit 11 from above, and a flexible body joined to the piezoelectric actuator 12 at the top of the head body 15. And a substrate 13. The flow path unit 11 has a configuration in which a plurality of plate members are stacked. FIG. 6 is a bottom view of the wiring board.

  3 shows a configuration when the head main body 15 in a state where the flow path unit 11 and the piezoelectric actuator 12 are joined is cut along a line III-III (a line along a nozzle row direction to be described later) in FIG. It is sectional drawing shown. As shown in FIG. 3, the flow path unit 11 has a plurality of nozzle holes 55 opened on the lower surface thereof, and the nozzle holes 55 form one or a plurality of rows extending in one direction. A plurality are arranged. The nozzle holes 55 arranged in one nozzle row are arranged at a predetermined interval from each other so that the same color liquid (ink) is ejected. The nozzle rows are arranged at appropriate intervals in a direction substantially perpendicular to the nozzle rows, and in this embodiment, six rows are provided for each color of liquid to be ejected.

  Hereinafter, the extending direction of the nozzle row is referred to as “nozzle row direction X”, and the nozzle row direction with respect to the nozzle row direction X is referred to as “nozzle row direction Y”. The liquid discharge head 2 is reciprocally scanned in the nozzle row direction Y.

  Inside the flow path unit 11, a manifold 51, which is a common storage chamber for temporarily storing a liquid, and a plurality of channels that individually connect the manifold 51 and each nozzle 85 are formed. The channel is provided corresponding to each nozzle 85 and has a pressure chamber 53 that temporarily stores liquid, a throttle portion 52 that communicates the manifold 51 and the pressure chamber 53, and a descender that communicates the nozzle 85 and the pressure chamber 53. Each space such as a hole 54 is formed.

  As shown in FIG. 2, a liquid supply port 17 connected to a liquid tank (not shown) is provided on the upper surface of the flow path unit 11 for each color of liquid. The liquid supplied from the liquid tank to each liquid supply port 17 flows into the manifold 51 in the flow path unit 11 and reaches the pressure chamber 53 via the throttle portion 52. When the liquid in the pressure chamber 53 receives a discharge pressure by driving the piezoelectric actuator 12, the pressure wave propagates to the liquid near the nozzle hole 55 through the descender hole 54, and the liquid is discharged from the nozzle hole 55. It has become so.

[Piezoelectric actuator]
4 shows a configuration when the head main body 15 in a state where the flow path unit 11 and the piezoelectric actuator 12 are joined is cut along the IV-IV line in FIG. 2 (that is, a line along the nozzle row direction). FIG. 5 is a plan view of the piezoelectric actuator 12.

  As shown in FIGS. 3 and 4, the piezoelectric actuator 12 is laminated and bonded to the upper surface of the flow path unit 11 and closes the pressure chamber 53 opened on the upper surface of the flow path unit. The piezoelectric actuator 12 includes a piezoelectric layer 23 made of a piezoelectric material (for example, PZT), and a base layer 24 that is laminated on the upper surface and bonded to the upper surface of the flow path unit 11. The piezoelectric layer 23 is further composed of two upper and lower layers of an upper piezoelectric layer 21 and a lower piezoelectric layer 22. In addition, on the upper surface of the upper piezoelectric layer 21, individual electrodes (drive electrodes) 42 are provided corresponding to the pressure chambers 53, and each individual electrode 42 is provided between the upper piezoelectric layer 21 and the lower piezoelectric layer 22. The upper constant potential electrode (high potential electrode) 46 is provided corresponding to (that is, corresponding to each pressure chamber 53). Further, a lower constant potential electrode (low potential electrode) 47 is provided between the lower piezoelectric layer 22 and the bottom layer 24. Hereinafter, the stacking direction of the piezoelectric layers 23 constituting the piezoelectric actuator 12 is referred to as “stacking direction Z”.

  Among the electrodes, the individual electrodes 42 are juxtaposed at substantially constant intervals along the nozzle row direction X on the upper surface of the upper piezoelectric layer 21 so as to face the pressure chambers 53. It is shifted and arranged. A part of each individual electrode 42 protrudes in the nozzle row direction Y, and this protrusion serves as a connection terminal 41 connected to the individual electrode connection land 60 (see FIG. 6) of the flexible substrate 13.

  The upper constant potential electrodes 46 are arranged at substantially constant intervals along the nozzle column direction X on the upper surface of the lower piezoelectric layer 22, and the columns of the upper constant potential electrodes 46 thus formed are arranged in the nozzle row direction Y. A plurality of them are arranged side by side. Therefore, the upper constant potential electrode 46 and the individual electrode 42 are provided overlapping in the stacking direction Z. Further, all the upper constant potential electrodes 46 included in the piezoelectric actuator 12 are electrically connected, and a common potential is applied to all the upper constant potential electrodes 46.

  The lower constant potential electrode 47 is formed in a strip shape extending along the nozzle row direction X so as to be a common electrode for the pressure chambers 53 arranged along the nozzle row direction X. The upper constant potential electrode 46 and the individual electrode 42 overlap in the stacking direction Z. All the lower constant potential electrodes 47 provided in the piezoelectric actuator 12 are electrically connected, and a common potential is applied to all the lower constant potential electrodes 47.

  Here, as shown in the sectional view of FIG. 4, the dimension of the upper constant potential electrode 46 in the nozzle array direction X is smaller than the dimension of the individual electrode 42 in the nozzle array direction X and is viewed along the stacking direction Z. The upper constant potential electrode 46 is arranged at the approximate center of the individual electrode 42 in the nozzle row direction X. Therefore, the individual electrode 42, the upper constant potential electrode 46, and the lower constant potential electrode 47 overlap in the stacking direction Z at a substantially central portion of the individual electrode 42 in the nozzle row direction X. The portion where the upper piezoelectric layer 21 is sandwiched between the individual electrode 42 and the upper constant potential electrode 46 in the piezoelectric actuator 12 in this manner is hereinafter referred to as a “first active portion 36”. On the other hand, at both ends of the individual electrode 42 in the nozzle row direction X, the individual electrode 42 and the lower constant potential electrode 47 overlap in the stacking direction Z, and the upper constant potential electrode 46 exists between these electrodes. do not do. In this way, in the piezoelectric actuator 12, a portion in which the upper piezoelectric layer 21 and the lower piezoelectric layer 22 are sandwiched between both end portions of the individual electrode 42 in the nozzle row direction X and the lower constant potential electrode 47 is hereinafter referred to as “ It is referred to as a second active part 37, 37 ".

  As shown in FIG. 5, the first surface common electrode 44 and the second surface common electrode 43 are formed on both ends of the upper surface of the piezoelectric actuator 12 in the nozzle row direction Y. Among these, the first surface common electrode 44 is electrically connected to the upper constant potential electrode 46 through a conductive material filled in a through hole penetrating the upper piezoelectric layer 21 in the stacking direction Z. The second surface common electrode 43 is electrically connected to the lower constant potential electrode 47 via a conductive material filled in a through hole penetrating the upper piezoelectric layer 21 and the lower piezoelectric layer 22 in the stacking direction Z. It is connected.

  As shown in FIGS. 3 and 4, in the piezoelectric actuator 12 having the above-described configuration, the individual electrode 42, the upper constant potential electrode 46, the lower constant potential electrode 47, and the individual electrode 42 and the lower constant potential electrode 47 are sandwiched. The portion of the piezoelectric layer 23 constitutes an energy generating unit 40 provided corresponding to each pressure chamber 53 in order to apply a liquid discharge pressure in the pressure chamber 53. In order to input a drive signal (drive voltage) to the energy generator 40, the connection terminal 41 described above is provided corresponding to each energy generator 40, and the connection terminal 41 extends in the nozzle row direction X. One or a plurality of rows are arranged on the upper surface of the piezoelectric actuator 12.

[Flexible substrate]
Next, the flexible substrate 13 will be described. As shown in FIG. 2, the flexible substrate 13 includes a COF (chip on film) 64 as a first flexible substrate on which a drive circuit 66 is mounted, and an FPC (flexible print cable) as a second flexible substrate. 65. These COF 64 and FPC 65 have a plurality of wirings formed on one side of a first base sheet 64a and a second base sheet 65a, which are rectangular electrically insulating flexible sheet materials, and are connected to each other and to the piezoelectric actuator 12. Is done.

  6A and 6B are diagrams showing the configuration of the flexible substrate 13 shown in FIG. 2. FIG. 6A is a schematic bottom view of the COF 64, and FIG. 6B is a schematic plan view of the FPC 65. As shown in FIG. 6 (a), the COF 64 has a connection electrode 35a with the FPC 65 at one end (lower surface) of the first base sheet 64a in the nozzle row direction X, and the longitudinal direction of the nozzle. The drive circuit 66 is mounted in the vicinity thereof along the row direction Y. Further, on the same surface as the mounting surface of the drive circuit 66, first low potential bias lines (first low potential wirings: COM) 31, 31 are formed at both ends in the nozzle row direction Y so as to be parallel to these. Inside, first high-potential bias lines (first high-potential wiring: VCOM) 33 and 33 are formed, and ends of the bias lines 31 and 33 in the nozzle row direction Y are connected to the connection electrode 35a. Yes.

  A plurality of individual electrode connection lands 60 are formed between the first high potential bias lines 33 and 33, and a plurality of common electrode connection lands 60 are disposed on the first low potential bias line 31 and the first high potential bias line 33. Electrode connection lands 32 and 34 are formed.

  The lower surface of the first base sheet 64a is covered with a cover layer made of a flexible synthetic resin (for example, polyimide resin or epoxy resin) having electrical insulation, while the common electrode connection lands 32 and 34 are covered. In addition, a hole is formed in a portion of the cover layer that overlaps with the individual electrode connection land 60, and a bump electrode is fixed to the common electrode connection land 32, 34 and the individual electrode connection land 60 exposed in the hole. The common electrode connection lands 32 and 34 and the individual electrode connection land 60 included in the COF 64 are connected to the first surface common electrode 44, the second surface common electrode 43, and the individual electrode 42 included in the piezoelectric actuator 12 through the bump electrodes. Connected terminal 41 (see FIG. 5).

  An output side wiring 71 for applying a driving potential to the driving electrode 42 of the piezoelectric actuator 12 extends from the driving circuit 66 so as to translate the lower surface of the first base sheet 64 a by the same number as the individual electrode connection land 60. Each of them is independently connected to each individual electrode connection land 60. An input side wiring 72 for inputting a control signal for operating the elements in the driving circuit 66 is extended from the drive circuit 66 so as to translate in the same number as the output side wiring 71. The input side wiring 72 is connected to the connection electrode 35a.

  Further, in the space between the group of the plurality of input side wirings 72 and the first high potential bias line 33, first low potential drive lines (VSS) 73, 73 for connecting the connection electrode 35a and the drive circuit 66 are provided. Is formed. Also, in the space, outside the first low potential drive lines 73 and 73, first high potential drive lines (VDD) 74 and 74 for connecting the connection electrode 35a and the drive circuit 66 are formed. ing. The first low potential drive line 73 and the first high potential drive line 74 apply a ground potential or a predetermined high potential to the drive circuit 66, respectively. Is selectively applied to the individual electrode 42. The output side wiring 71, the input side wiring 72, the first low potential driving line 73, and the first high potential driving line 74 are also covered with the cover layer.

  On the other hand, as shown in FIG. 6B, a connection electrode 35b for connecting to the COF 64 is provided at one end portion in the nozzle row direction Y of the FPC 65 so that the longitudinal direction thereof is along the nozzle row direction Y. ing. From the connection electrode 35b, four wires extend in parallel toward one side in the nozzle row direction X. Among these, the wirings located at both ends are second low potential bias lines (second low potential wirings: COM) 82 and 82, and the connection electrodes 35a and 35b are joined to form the first low potential bias line 31 of the COF 64. Conducted to 31. Further, the two wires positioned between the second low potential bias lines 82 and 82 are the second low potential drive lines 83 and 83, and are electrically connected to the first low potential drive lines 73 and 73 of the COF 64. The second low-potential bias lines 82 and 82 and the second low-potential drive lines 83 and 83 merge on the FPC 65 to form one third low-potential wiring 84, and on the FPC 65 in the nozzle row direction. It extends along Y.

  Further, four wires are extended in parallel from the connection electrode 35b toward the other side in the nozzle row direction X. Among these, the wirings located at both ends are second high potential bias lines (second high potential wiring: VCOM) 85 and 85, and the connection electrodes 35a and 35b are joined to form the first high potential bias line 33 of the COF 64. Conducted to 33. Further, the two wirings positioned between the second high potential bias lines 85 and 85 are the second high potential drive lines 86 and 86 and are electrically connected to the first high potential drive lines 74 and 74 of the COF 64. The second high-potential bias lines 85 and 85 and the second high-potential drive lines 86 and 86 merge on the FPC 65 to form one third high-potential wiring 87, and on the FPC 65 in the nozzle row direction. It extends along Y.

  Here, each open side terminal of the third low potential wiring 84 and the third high potential wiring 87 (that is, a terminal on the upper side in the nozzle row direction Y in FIG. 6B) is connected to the lower constant potential electrode 47 during liquid ejection. And an input terminal for potentials (COM and VCOM) for biasing the upper constant potential electrode 46, and for inputting a drive potential (VSS and VDD) selectively applied to the individual electrode 42 to the drive circuit 66 for relaying. A terminal is also formed, and further a measurement terminal for detecting the connection state of the wiring is formed as described below from the impedance measurement value between both terminals.

[Wiring status detection method]
The piezoelectric actuator 12 and the flexible substrate 13 configured as described above constitute a drive unit 90 according to the present embodiment. Hereinafter, the configuration and method for detecting the connection state between the bias lines 31 and 33 provided in the COF 64 and the bias lines 82 and 85 provided in the FPC 65 in the drive unit 90 will be described.

FIG. 7 is a diagram showing an equivalent circuit of the drive unit 90 when detecting the wiring state. FIG. 8 is a flowchart showing a procedure for detecting the wiring state of the drive unit 90. As shown in FIG. 7, when detecting the wiring state, an impedance measuring instrument 91 is connected between the third low potential wiring 84 and the third high potential wiring 85 (FIG. 8: S1). As shown in FIGS. 3 and 4, the upper constant potential electrode 46 and the lower constant potential electrode 47 arranged to face each other are regarded as a kind of capacitors C _{1 to} C _N (N is the same number as the pressure chamber 53). A predetermined capacitance is formed between the electrodes 46 and 47. Accordingly, the impedance measuring device 91, the third low potential wiring 84, the second low potential bias line 82, the first low potential bias line 31, the capacitors C _{1 to} C _N , the first high potential bias line 33, and the second high potential bias. One closed circuit is formed by the line 85 and the third high potential bias line 87.

  The impedance measuring device 91 according to the present embodiment includes a power source 92 that outputs a pulse signal to a closed circuit, a voltmeter 93 that detects a voltage across the third low potential wiring 84 and the third high potential wiring 85, and , And an ammeter 94 for detecting the sum of currents flowing through the closed circuit.

  Next, in the closed circuit as described above, a pulse signal is output from the power source 92 of the impedance measuring device 91 (FIG. 8: S2), and the impedance in the closed circuit is measured from the detected values of the voltmeter 93 and the ammeter 94. (FIG. 8: S3). On the other hand, the impedance in the closed circuit when the bias lines 31 and 33 provided in the COF 64 and the bias lines 82 and 85 provided in the FPC 65 are appropriately connected is measured in advance, and this is used as a reference. Impedance. Next, the measured value and the reference impedance are compared (FIG. 8: S4). If the measured value is approximately the same as the reference impedance, it is determined that the connection state is good (FIG. 8: S5), and the measured value is the reference. If it is larger than the impedance, it is determined that there is a defect in the connection state and there is a possibility of disconnection (FIG. 8: S6).

  Here, the reason for determining that the connection state is incomplete will be described. In the following description, the two first low-potential bias lines 31 are distinguished as the first low-potential bias lines 31a and 31b, respectively, as necessary, and connected to the first low-potential bias lines 31a and 31b. The two first high potential bias lines 33 are also distinguished from each other as first high potential bias lines 33a and 33b.

As shown in FIG. 7, the bias lines 31 and 33 provided in the COF 64 and the bias lines 82 and 85 provided in the FPC 65 are connected to the four contacts P _{1 to} P ₄ . First, when all of the contacts P _{1 to} P ₄ are properly connected, most of the pulse signals from the power source 92 are transmitted from the contact P ₁ to the first low potential bias line 31a, the capacitor C ₁ , and and route Ra leading to the contacts P ₃ via a first high potential bias line 33a, extending from the contact P _2, the first low potential bias line 31b, through a capacitor C _N, and the first high potential bias line 33b to the contact point P ₄ It flows along the route Rb. That is, only the capacitors C ₁ and C _N are passed, and the capacitors C _{2 to} C _N-1 are not passed. The impedance at this time becomes the reference impedance.

On the other hand, if the contact P ₁ is disconnected, the pulse signal cannot flow through the route Ra passing through the contact P _1. Therefore, the first high potential bias line 33a passes through the capacitors C _{1 to} C _N from the contact P _2. , 33b (see broken line arrows in FIG. 7). For this reason, it is influenced by the resistance component r inherent in all the capacitors C _{1 to} C _N , and the measured value by the impedance measuring device 91 becomes larger than the reference impedance. Accordingly, when the measured value is larger than the reference impedance, at least _one of the contact points P _{1 to} P ₄ that are connection points with the bias lines 31 and 33 provided on the COF 64 and the bias lines 82 and 85 provided on the FPC 65. It can be determined that there is a connection failure at one location.

According to the drive unit 90 configured as described above and the wiring state detection method thereof, the drive unit 90 is provided with the bias lines 31 and 33 provided in the COF 64 and the FPC 65 without separately providing a dedicated configuration in advance. It is possible to easily detect the state of the connection points with the bias lines 82 and 85. Moreover, even if it is not possible to confirm visually the respective connection points (contact point P ₁ to P _4), it is possible to reliably detect the connection status.

[Other configuration of drive unit (1)]
FIG. 9 is a cross-sectional view showing a configuration when the head main body 15a of the drive unit 90a having a configuration different from that described above is cut along a line along the nozzle row direction Y. FIG. FIG. 10 is a diagram showing an equivalent circuit of the drive unit 90a when the wiring state is detected in the drive unit 90a shown in FIG.

  As shown in FIG. 9, the head body 15 a includes a flow path unit 11 similar to that shown in FIG. 3, but includes a piezoelectric actuator 12 a having a slightly different configuration from the piezoelectric actuator 12. More specifically, the piezoelectric actuator 12a shown in FIG. 9 is located between the bottom layer 24 and the lower piezoelectric layer 22 and on both outer sides in the nozzle row direction Y in the region where the lower constant potential electrode 47 is provided. Are provided between the lower piezoelectric layer 22 and the upper piezoelectric layer 21 and on both outer sides in the nozzle row direction Y in the region where the upper constant potential electrode 46 is provided. High potential relay electrodes 111 and 111 are provided.

  Among these, the low potential relay electrode 110 passes through the upper piezoelectric layer 21 and the lower piezoelectric layer 22 with respect to the second surface common electrodes 43 and 43 formed at both ends in the nozzle row direction Y on the upper surface of the piezoelectric actuator 12a. It conducts through a conductive material filled in the hole, and conducts to the lower constant potential electrode 47 through a wiring formed on the upper surface of the bottom layer 24. Therefore, the low potential relay electrode 110 is in a position to electrically relay the second surface common electrode 43 (see FIG. 5) and the lower constant potential electrode 47.

  On the other hand, the high potential relay electrode 111 is a conductive material filled in a through hole penetrating the upper piezoelectric layer 21 with respect to the first surface common electrodes 44 and 44 formed at both ends in the nozzle row direction Y on the upper surface of the piezoelectric actuator 12a. The conductive layer is electrically connected to the upper constant potential electrode 46 via a wiring formed on the upper surface of the lower piezoelectric layer 22. Therefore, the high potential relay electrode 111 is in a position to electrically relay the first surface common electrode 44 (see FIG. 5) and the upper constant potential electrode 46.

As shown in FIG. 9, the low potential relay electrode 110 and the high potential relay electrode 111 overlap in the stacking direction Z, in other words, are arranged to face each other. As a result, capacitors C _A and C _B composed of the low potential relay electrode 110 and the high potential relay electrode 111 are formed at both ends of the piezoelectric actuator 12 in the nozzle row direction Y. These capacitors C _A and C _B have a predetermined capacitance independent of the capacitance of the capacitors C _{1 to} C _N formed between the lower constant potential electrode 47 and the upper constant potential electrode 46. In this embodiment, the capacitors C _{1 to} C _N have a larger capacitance than the sum of the capacitances.

  Note that the piezoelectric substrate 12a is bonded to the flexible substrate 13 shown in FIG. 6 and operates in the same manner as the piezoelectric actuator 12 described with reference to FIGS. Can be realized.

As shown in FIG. 10, when the wiring state is detected in such a drive unit 90a, the same configuration as that shown in FIG. 7 is adopted, that is, the third low potential wiring 84 and the third high potential wiring 85. An impedance measuring device 91 is connected between the two. Then, it is possible to detect whether there is a connection failure in any of the contacts P _{1 to} P ₄ by the same procedure as that shown in the flowchart of FIG. Further, in the drive unit 90a, since the capacitor C _A, the C _B provided separately from the capacitor C ₁ -C _N formed by the upper constant potential electrodes 46 and the lower constant potential electrodes 47, the capacitor C _A, By appropriately setting the capacitance of C _B , the difference between the impedance measurement value and the reference impedance when there is a connection failure can be adjusted, and the detection accuracy of the presence or absence of connection failure can be improved.

Further, in the drive unit 90a according to this embodiment, the capacitor C _A, the capacitance of C _B and larger than the sum of the capacitance of the capacitor C ₁ -C _N, capacitor capacitor C _A, of C _B The reactance component of the impedance is relatively small. Accordingly, the contacts P _{1 to} P ₄ are properly connected, and the measured impedance value (that is, the reference impedance) in a state where the pulse signal passes through the routes Ra and Rb becomes relatively small, but there is a poor connection. In a state where the pulse signal passes through the ten broken arrows, the impedances of the capacitors C _{1 to} C _N having relatively large reactance components are included in the measured value. Therefore, when there is a connection failure, the difference between the impedance measurement value and the reference impedance is increased, and the detection accuracy of the connection failure can be improved.

Note that the capacitances of the two capacitors C _A and C _B may be the same or different from each other.

[Other configuration of drive unit (2)]
FIG. 11 is a cross-sectional view showing a configuration when the head main body 15b of the drive unit 90b having a configuration different from that described above is cut along a line along the nozzle row direction X. FIG. As shown in FIG. 11, the head main body 15b includes a flow path unit 11 similar to that shown in FIG. 4, but includes a piezoelectric actuator 12b that is slightly different from the piezoelectric actuator 12 shown in FIG. More specifically, the lower constant potential electrode 47b of the piezoelectric actuator 12b has a configuration in which only an overlapping portion in the stacking direction Z with the upper constant potential electrode 46 is omitted.

  With such a configuration, when a signal that changes between a high potential and a low potential is input to the individual electrode 42, electrolysis does not occur in the lower piezoelectric layer 22 immediately below the upper constant potential electrode 46. This part can be prevented from being deformed. Therefore, crosstalk associated with the deformation of this portion can be suppressed and power consumption can be reduced.

On the other hand, if the portion of the lower constant potential electrode 47 facing the upper constant potential electrode 46 is omitted, the capacitors C _{1 to} C _N cannot be formed as shown in FIG. However, by providing the low potential relay electrode 110 and the high potential relay electrode 111 shown in FIGS. 9 and 10, the connection state at the contacts P _{1 to} P ₄ can also be detected. Hereinafter, a method for detecting the wiring state in the drive unit 90b will be described.

FIG. 12 is a diagram showing an equivalent circuit of the drive unit 90b when the wiring state is detected in the drive unit 90b shown in FIG. As shown in FIG. 12, in the case of the drive unit 90b, capacitors CA and CB are formed by two low potential relay electrodes 110 and two high potential relay electrodes 111. There are no capacitors C _{1 to} C _N , and the resistance r ₁ inherent in the upper constant potential electrode 46 between the two low potential relay electrodes 110, 110 and between the two high potential relay electrodes 111, 111, There is a resistance r ₂ inherent in the lower constant potential electrode 47.

In such a drive unit 90b, if the four contacts P ₁ to P ₄ are properly connected, in the same manner as described with reference to FIG. 7, the input pulse signal from the contact P _1, the 1 low potential bias line 31a, capacitor C ₁ , route Ra through first high potential bias line 33a to contact P ₃ , contact P ₂ , first low potential bias line 31b, capacitor C _N , and first It flows through a route Rb that reaches the contact point P ₄ through the high potential bias line 33b. In other words, the impedance (reference impedance) measured in this case does not include the resistances r ₁ and r ₂ .

On the other hand, if the contact P ₁ is disconnected, the pulse signal cannot flow through the route Ra passing through the contact P _1, and therefore the first high potential bias line 33a from the contact P ₂ via the resistors r ₁ and r _2. , 33b (see broken line arrows in FIG. 12). Therefore, the impedances to be measured include the resistors r ₁ and r _2, which are larger than the reference impedance. Accordingly, when the measured value is larger than the reference impedance, it can be determined that there is a connection failure in at least one of the contacts P _{1 to} P ₄ .

  The present invention relates to a drive unit of a liquid ejection device capable of easily detecting a connection state of a connection portion between substrates for wiring provided across two connected substrates, and a wiring state detection method of the drive unit And can be applied to

2 Liquid discharge head 11 Flow path unit 12, 12a, 12b Piezoelectric actuator 13 Flexible substrate 31 First low potential bias line (first low potential wiring: COM)
33 First high potential bias line (first high potential wiring: VCOM)
42 Individual electrodes (drive electrodes)
46 Upper constant potential electrode (high potential electrode)
47 Lower constant potential electrode (low potential electrode)
53 Pressure chamber 64 COF
64a First base sheet 65 FPC
65a Second base sheet 66 Drive circuit 73 First low potential drive line (VSS)
74 First high potential drive line (VDD)
82 Second low potential bias line (second low potential wiring: COM)
83 Second low potential drive line (VSS)
84 Third low potential wiring 85 Second high potential bias line (second high potential wiring: VCOM)
86 Second high potential drive line (VDD)
87 3rd high potential wiring 90, 90a, 90b Drive unit 91 Impedance measuring device 100 Liquid discharge apparatus

Claims (4)

Two first low-potential lines connected to the low-potential electrode and two lines connected to the high-potential electrode are connected to an actuator in which a low-potential electrode, a high-potential electrode, and a drive electrode are stacked with a piezoelectric layer in between. The first sheet base material having the first high potential wiring is connected to the first sheet base material, two second low potential wirings connected to the first low potential wiring, A second sheet base material having two second high potential wirings connected to the first high potential wiring is connected, and the two second low potential wirings and the two second high potential wirings are: A method of detecting a wiring state of a drive unit of a liquid ejection apparatus, which is formed by joining each of the second sheet base materials to form one third low potential wiring and a third high potential wiring,
Connecting a measuring instrument between the third low potential wiring and the third high potential wiring of the drive unit, and obtaining an impedance measurement value between the two wirings;
The first low potential wiring and the second low potential wiring, and the first high potential wiring and the second high potential wiring are both electrically connected. A method for detecting a wiring state of a drive unit, comprising: comparing a reference impedance, which is an impedance between a third low potential wiring and the third high potential wiring, with the measured impedance value. A low-potential electrode biased to a low potential, a high-potential electrode biased to a high potential, and a driving potential that changes over time are provided corresponding to a pressure chamber to which a pressure for discharging liquid from the nozzle hole is applied. An actuator having an active portion in which a drive electrode to be applied is stacked in this order across a piezoelectric layer;
A first sheet base material having two first low potential wires connected to the low potential electrode and two first high potential wires connected to the high potential electrode and connected to the actuator; ,
Two second low potential wirings connected to each of the first low potential wirings, two second high potential wirings connected to each of the first high potential wirings, and the two second low potential wirings. A second sheet base material having a third low potential wiring formed by joining and a third high potential wiring formed by joining the two second high potential wirings and connected to the first sheet base material; With
In the actuator, the active portion is disposed between a location on the way from each first low potential wiring to the low potential electrode and a location on the way from each first high potential wiring to the high potential electrode. Two capacitances independent of the part are formed,
Each open-side terminal of the third low potential wiring and the third high potential wiring forms an input terminal for biasing the low potential electrode and the high potential electrode when liquid is discharged, and via the capacitance. A measurement terminal for detecting a connection state between the first low-potential wiring and the first high-potential wiring and the second low-potential wiring and the second high-potential wiring from the impedance measurement value is also formed. A drive unit for the liquid ejection device.   The drive unit of the liquid ejection apparatus according to claim 2, wherein the capacitance is larger than a capacitance between the low potential electrode and the high potential electrode.   The actuator includes two low potential relay units that relay a potential input from each first low potential wiring to the plurality of low potential electrodes, and a plurality of potentials input from the first high potential wiring. The high-potential relay section has two high-potential relay sections, and the capacitance is provided between each of the low-potential relay sections and each of the high-potential relay sections. The drive unit of the liquid discharge apparatus of Claim 2 or 3.

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