Liquid ejection head

Abstract

To provide a liquid discharge head which can measure a resistance of a common wiring for giving common potential to a plurality of actuators.SOLUTION: A liquid discharge head comprises a plurality of actuators, a plurality of individual wirings, a common wiring, and a monitor terminal. The plurality of actuators are arranged on a substrate. The plurality of individual wirings are each connected to one terminal of each actuator, and formed to a terminal part on a periphery of the substrate. The common wiring comprises: a first wiring part which is formed in an arrangement direction of the actuators on one edge side of the substrate, and in which a pair of terminals pulled out from both sides in the arrangement direction of the actuators are formed to the other edge side of the substrate; and a plurality of second wiring parts which are branched from the first wiring part respectively, and connected to the other terminals of the actuators. The monitor terminal is located between the pair of terminals of the first wiring part on the other edge side of the substrate, and is connected to the first wiring part.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] Embodiments of the present invention relate to a liquid ejection head.

Background Art

[0002] A liquid ejection head that supplies a predetermined amount of liquid to a predetermined position is known. The liquid ejection head is mounted on, for example, an inkjet printer, a 3D printer, a dispensing device, or the like. An inkjet printer ejects ink droplets from an inkjet head to form an image or the like on the surface of a recording medium. A 3D printer ejects droplets of a modeling material from a modeling material ejection head and cures them to form a three-dimensional object. A dispensing device ejects droplets of a sample and supplies a predetermined amount to a plurality of containers or the like.

[0003] The liquid ejection head has a plurality of channels for ejecting liquid. Each channel includes a nozzle for ejecting liquid, a pressure chamber communicating with the nozzle, and an actuator for changing the volume of the pressure chamber. The liquid ejection head selects a channel for ejecting liquid from among the plurality of channels and drives it by applying a drive signal to the actuator. When the actuator is driven, the volume of the pressure chamber filled with liquid changes, and liquid is ejected from the nozzle.

[0004] One terminal of the actuator is connected to an individual wiring for applying a drive voltage. The other terminal of the actuator is connected to a common wiring for applying a common potential to each actuator. It is desirable that this common potential be constant. However, in reality, the common potential may not be constant due to the resistance of the common wiring. If the common potential varies, it may affect the liquid ejection characteristics. Therefore, it is necessary to measure the resistance of the common wiring so that the resistance of the common wiring can be managed at a low value.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0006] The problem to be solved by the present invention is to provide a liquid ejection head capable of measuring the resistance of a common wiring that applies a common potential to a plurality of actuators.

Means for Solving the Problems

[0007] The liquid ejection head according to an embodiment of the present invention includes a plurality of actuators, a plurality of individual wirings, a common wiring, and a monitor terminal. The plurality of actuators are arranged on a substrate. The plurality of individual wirings are respectively connected to one terminal of each of the actuators and formed to reach a terminal portion at an edge of the substrate. The common wiring is formed on the other edge side of the substrate in the arrangement direction of the actuators, and further includes a first wiring portion formed with a pair of terminals drawn out from both sides in the arrangement direction of the actuators to one edge side of the substrate, and a plurality of second wiring portions branched from the first wiring portion and connected to the other terminals of the actuators. The monitor terminal is arranged in the middle of the pair of terminals of the first wiring portion on one edge side of the substrate and is connected to the first wiring portion.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Mode for Carrying Out the Invention

[0009] Hereinafter, a liquid ejection head according to an embodiment will be described in detail with reference to the accompanying drawings. In each figure, the same components are denoted by the same reference numerals.

[0010] As an example of an image forming apparatus equipped with the liquid ejection head of the embodiment, an inkjet printer 10 that prints an image on a recording medium will be described. FIG. 1 shows a schematic configuration of the inkjet printer 10. The inkjet printer 10 includes, inside a housing 11, a cassette 12 that stores a sheet S, which is an example of a recording medium, an upstream conveyance path 13 of the sheet S, a conveyance belt 14 that conveys the sheet S taken out from the cassette 12, a plurality of inkjet heads 100 to 103 that eject ink droplets toward the sheet S on the conveyance belt 14, a downstream conveyance path 15 of the sheet S, a discharge tray 16, and a control board 17. An operation unit 18, which is a user interface, is arranged on the upper side of the housing 11.

[0011] The image data to be printed on the sheet S is generated, for example, by a computer 200 which is an external connection device. The image data generated by the computer 200 is sent to the control board 17 of the inkjet printer 10 through the cable 201 and the connectors 202, 203.

[0012] The pickup roller 204 supplies the sheets S one by one from the cassette 12 to the upstream conveyance path 13. The upstream conveyance path 13 is composed of the feed roller pairs 131, 132 and the sheet guide plates 133, 134. The sheet S is sent to the upper surface of the conveyance belt 14 via the upstream conveyance path 13. The arrow 104 in the figure indicates the conveyance path of the sheet S from the cassette 12 to the conveyance belt 14.

[0013] The conveyance belt 14 is a net-shaped endless belt having a large number of through holes formed on its surface. The three rollers of the drive roller 141, the driven rollers 142, 143 rotatably support the conveyance belt 14. The motor 205 rotates the conveyance belt 14 by rotating the drive roller 141. The 105 in the figure indicates the rotation direction of the conveyance belt 14. A negative pressure container 206 is arranged on the back side of the conveyance belt 14. The negative pressure container 206 is connected to a decompression fan 207. The fan 207 makes the inside of the negative pressure container 206 negative pressure by the formed air flow, and adsorbs and holds the sheet S on the upper surface of the conveyance belt 14. The 106 in the figure indicates the flow of the air flow.

[0014] The inkjet heads 100 to 103 which are an example of the liquid ejection head are arranged so as to face the sheet S adsorbed and held on the conveyance belt 14 with a slight gap of, for example, 1 mm. The inkjet heads 100 to 103 eject ink droplets toward the sheet S respectively. The inkjet heads 100 to 103 print an image when the sheet S passes below. Each of the inkjet heads 100 to 103 has the same structure except that the color of the ejected ink is different. The colors of the ink are, for example, cyan, magenta, yellow, and black.

[0015] The inkjet heads 100 to 103 are each connected to ink tanks 315 to 318 and ink supply pressure regulators 321 to 324 via ink flow paths 311 to 314. Each of the ink tanks 315 to 318 is arranged above each of the inkjet heads 100 to 103. During standby, each of the ink supply pressure regulators 321 to 324 adjusts the pressure inside each of the inkjet heads 100 to 103 to a negative pressure with respect to atmospheric pressure, for example, -1.2 kPa, so that ink does not leak from the nozzles 25 (see FIG. 2) of the inkjet heads 100 to 103. During image formation, the ink in each of the ink tanks 315 to 318 is supplied to each of the inkjet heads 100 to 103 by the ink supply pressure regulators 321 to 324.

[0016] After image formation, the sheet S is sent from the conveyance belt 14 to the downstream conveyance path 15. The downstream conveyance path 15 is composed of pairs of feed rollers 151, 152, 153, 154 and sheet guide plates 155, 156 that define the conveyance path of the sheet S. The sheet S is sent from the downstream conveyance path 15 to the discharge tray 16 through the discharge port 157. The arrow 107 in the figure indicates the conveyance path of the sheet S.

[0017] Next, the configuration of the inkjet heads 100 to 103 will be described. The following describes the inkjet head 100 with reference to FIGS. 2 to 7, but the inkjet heads 101 to 103 have the same structure as the inkjet head 100.

[0018] As shown in FIG. 2, the inkjet head 100 includes a head portion 2 which is an example of a liquid ejection portion. The head portion 2 includes a nozzle plate 21, an actuator substrate 22, and an ink supply portion 23 which is an example of a liquid supply portion. The ink supply portion 23 is connected to the ink supply pressure regulator 321 in FIG. 1 via the ink flow path 311. The actuator substrate 22 of the head portion 2 is connected to a flexible printed wiring board 3 which is an example of a film wiring board. Further, the flexible printed wiring board 3 is connected to a printed board 4 as a relay board.

[0019] The flexible printed wiring board 3 mounts a driving IC (Integrated Circuit) 31 which is a driver chip (hereinafter referred to as the driving IC). The driving IC 31 may be mounted on a substrate different from the flexible printed wiring board 3 and connected from the different substrate to the flexible printed wiring board 3. The driving IC 31 as the control unit temporarily stores the print data from the control board 17 of the inkjet printer 10 sent via the printed board 4, and gives a driving signal to each channel so as to eject ink at a predetermined timing.

[0020] A nozzle plate 21 which is an example of the nozzle part is a rectangular plate formed of a resin such as polyimide or a metal such as stainless steel. The nozzles 25 of each channel for ejecting ink are arranged along the longitudinal direction (X direction) of the nozzle plate 22. The nozzle density is set, for example, within the range of 150 to 1200 dpi.

[0021] The actuator substrate 22 is a rectangular substrate formed of, for example, insulating ceramics. As shown in FIG. 3, a plurality of pressure chambers 51 and air chambers 52 are alternately formed on the actuator substrate 22 along a first direction, for example, the X direction. The pressure chamber 51 communicates with the nozzle 25. The pressure chamber 51 communicates with the ink supply unit 23 through, for example, a common ink chamber (not shown) formed in the actuator substrate 22. On the other hand, the air chamber 52 disposed adjacent to the pressure chamber 51 is, for example, a closed space that does not communicate with the nozzle 25 and the common ink chamber (not shown). The pressure chamber 51 and the air chamber 52 are formed by notching, for example, two piezoelectric members 26 laminated on the actuator substrate 22 in a direction where the polarization directions are opposite (for example, the opposing direction) in a second direction, for example, the Z direction, in a rectangular groove shape. That is, between the pressure chamber 51 and the air chamber 52, two piezoelectric members 26 laminated in a third direction, for example, the Y direction, are used as side walls to partition.

[0022] The electrode 53 is integrally formed on the bottom surface and both side surfaces of the groove-shaped pressure chamber 51. The electrode 53 of the pressure chamber 51 is connected to the individual wiring 54 which is a wiring electrode. The electrode 55 is integrally formed on the bottom surface and both side surfaces of the groove-shaped air chamber 52. The electrode 55 of the air chamber 52 is connected to the common wiring 56 which is a wiring electrode. That is, the connection point of the electrode 53 of the pressure chamber 51 and the individual wiring 54 is one terminal of the actuator 5. The connection point of the electrode 55 of the air chamber 52 and the common wiring 56 is the other terminal of the actuator 5. The individual wiring 54 is connected to the drive driver D (that is, the drive circuit) of the drive IC 31. The drive driver D of each channel gives the drive voltage V1 as a drive signal to the actuator 5 of each channel and drives them independently. The common wiring 56 is connected to, for example, the ground (GND). With this configuration, in the actuator 5 to which the drive voltage V1 is applied, an electric field is applied in a direction intersecting (preferably, orthogonal to) the polarization axis of the piezoelectric member 26, and the piezoelectric member 26 which is the side wall in the X direction of the pressure chamber 51 deforms symmetrically in the X direction in the shear mode.

[0023] That is, the pressure chamber 51 of the ink is formed by being sandwiched between a pair of columnar actuators 5 using the piezoelectric member 26. A potential difference is given to both walls of the columnar actuator 5, that is, the inner wall and the outer wall of the pressure chamber 51, and the actuator 5 is charged to deform the actuator 5. As a result, the volume of the pressure chamber 51 changes, and as a result, the ink pressure in the pressure chamber 51 changes. By adjusting the magnitude and timing of this change, the ink is ejected from the nozzle 25.

[0024] FIG. 4 is a plan view before connecting the actuator substrate 22, the flexible printed wiring board 3, and the printed circuit board 4 to each other. FIG. 5 is a partially enlarged view of the actuator substrate 22. FIG. 6 is a plan view showing a state where the substrates 22, 3, and 4 are connected to each other. FIG. 7 is a side view showing a state where the substrates 22, 3, and 4 are connected to each other.

[0025] The actuator substrate 22 and the flexible printed wiring board 3 are connected by overlapping their respective terminal portions 20 and 30. The flexible printed wiring board 3 and the printed circuit board 4 are connected by overlapping their respective terminal portions 32 and 40.

[0026] As described above, the actuator 5 has an individual wiring 54 connected to one of its terminals. A plurality of individual wirings 54 drawn from each actuator 5 are respectively formed up to the terminal portion 20 on one edge of the actuator substrate 22. One edge of the actuator substrate 22 is the edge of the substrate on the side where the flexible printed wiring board 3 is connected. At the terminal portion 20, the individual wirings 54 are formed in parallel, for example, at equal intervals.

[0027] The common wiring 56 includes a first wiring portion 57 and a second wiring portion 58. The first wiring portion 57 and the second wiring portion 58 are arranged on the side opposite to the terminal portion 20 as viewed from the actuator 5 so as not to intersect the individual wirings 54. The first wiring portion 57 is formed along the arrangement direction of the actuators 5 on the other edge side of the actuator substrate 22, and further, both ends, for example, both end portions in the arrangement direction of the actuators 5 are folded back in a direction intersecting the arrangement direction of the actuators 5 and formed up to the terminal portion 20. Therefore, at the terminal portion 20, a pair of terminals drawn from both ends of the first wiring portion 57 are symmetrically located on both sides of the substrate. The direction intersecting the arrangement direction of the actuators 5 is, for example, a direction perpendicular thereto. A plurality of second wiring portions 58 branched from the first wiring portion 57 are formed along the direction intersecting the arrangement direction of the actuators 5 and are respectively connected to the other terminals of the actuators 5.

[0028] The monitor terminal 59 is arranged on the side for connecting the flexible printed wiring board 3. The monitor terminal 59 is connected to the first wiring portion 57 of the common wiring 56 and is used when measuring the resistance of the first wiring portion 57 as will be described in detail later. As an example, the monitor terminal 59 is formed in a wiring shape passing between adjacent individual wirings 54 and further connected to the first wiring portion 57 through between adjacent actuators 5. In the example of the figure, a part of the monitor terminal 59 is formed by the electrode 55 (see FIG. 3) of the air chamber 51 and the second wiring portion 58. That is, the monitor terminal 59 is connected to the first wiring portion 57 across the arrangement of the actuators 5 without intersecting other wirings such as the individual wiring 54 and the second wiring portion 58 of another channel by being drawn out using the electrode 55 in the air chamber 51. In the case of a head structure without the air chamber 51, etc., the monitor terminal 59 may be an independent wiring and connected to the first wiring portion 57.

[0029] The monitor terminal 59 is formed at a position corresponding to the center in the length direction of the first common electrode 57 extending along the arrangement direction of the actuators 5. Preferably, it is at a position where the first common electrode 57 is symmetrically divided into two. The monitor terminal 59 does not necessarily have to be one in the center, and a plurality of monitor terminals 59 may be provided using the electrodes in a plurality of air chambers. By increasing the number of monitor terminals 59, the electrode resistance can be managed more finely. Also, as a preferred example, the interval between the monitor terminal 59 and the adjacent individual wiring 54 and the interval between the adjacent individual wirings 54 are adjusted so that the pitch P of each terminal in the terminal portion 20 is made uniform (see FIG. 5). If arranged in this way, there is an advantage that the monitor terminal 59 and the terminals for capacitance measurement described later are equally spaced, facilitating batch probing.

[0030] The individual wiring 54, the first wiring portion 57, the second wiring portion 58, and the monitor terminal 59 are formed in a thin film shape, for example, of nickel, aluminum, gold, or an alloy thereof. The wiring widths of the individual wiring 54, the second wiring portion 58, and the monitor terminal 59 are selected, for example, from within the range of 10 μm to 30 μm. Since the first wiring portion 57 needs to supply charge and discharge currents to all the actuators 5, the wiring width is made larger than that of the second wiring portion 58. The wiring width is, for example, 0.8 mm. The thicknesses of the individual wiring 54, the first wiring portion 57, the second wiring portion 58, and the monitor terminal 59 are, for example, 0.4 μm. For ensuring insulation, an insulating layer, an insulating member, etc. may be provided, for example, in a region excluding the terminal portion 20.

[0031] The flexible printed wiring board 3 is a flexible printed wiring substrate using a synthetic resin film such as polyimide, for example. The drive IC 31 is a driver chip formed on a silicon semiconductor substrate, for example. On the flexible printed wiring board 3, an output wiring 33, an input wiring 34, a power supply wiring 35 for voltage V1, a ground wiring 36, and a common passage wiring 37 are formed. It is preferable to form these wirings 33 to 37 and the drive IC 31 on one side of the flexible printed wiring board 3. An example of the flexible printed wiring board 3 is a COF (Chip on Film). The output wiring 33 drawn from the drive IC 31 is formed up to the terminal portion 30. The output wiring 33 is an individual wiring formed on the flexible printed wiring board 3. The number of the output wirings 33 is made, for example, the same as the number of the individual wirings 54 on the actuator substrate 22 side.

[0032] The common passage wiring 37 is formed from the terminal portion 30 on the side connecting the actuator substrate 22 to the terminal portion 32 on the side connecting the printed board 4. The common passage wiring 37 is formed in a pair on both sides of the substrate and is respectively connected to the terminals of the first wiring portion 57 formed in a pair at the terminal portion 20 of the actuator substrate 22 to mitigate the voltage drop generated in the first wiring portion 57 during driving.

[0033] The input wiring 34 drawn from the drive IC 31 is formed up to the terminal portion 32 on the side connecting the printed circuit board 4. Since the drive IC 31 can be controlled by serial communication, the number of input wirings 34 can be made smaller than the number of output wirings 33.

[0034] The power supply wiring 35 and the ground wiring 36 are respectively connected to the drive IC 31. The power supply wiring 35 and the ground wiring 36 are respectively formed up to the terminal portion 32 on the side connecting the printed circuit board 4. The output wiring 33, the input wiring 34, the power supply wiring 35, the ground wiring 36, and the common passing wiring 37 are formed in a thin film shape of, for example, copper.

[0035] The printed circuit board 4 is a rigid through-hole board in which an epoxy resin layer containing glass fibers and a copper wiring layer are laminated multiple times. Output wiring 41, power supply wiring 42, and ground wiring 43 are respectively formed at the terminal portion 40. The output wiring 41 is connected to the input wiring 34 of the flexible printed wiring board 3. The power supply wiring 42 is connected to the power supply wiring 35 of the flexible printed wiring board 3. The ground wiring 43 is connected to the ground wiring 36 and the common passing wiring 37 of the flexible printed wiring board 3. A signal for selectively driving each actuator 5 sent from the control board 17 of the inkjet printer 10 is applied to the output wiring 41. A drive voltage V1 is applied to the power supply wiring 42. The ground wiring 43 is connected to the ground (GND) by, for example, the control board 17 of the inkjet printer 10.

[0036] Particularly, as shown in FIG. 7, the terminal portion 20 of the actuator substrate 22 and the terminal portion 30 of the flexible printed wiring board 3 are connected via an anisotropic conductive film (ACF). That is, the terminal portion 20 of the actuator substrate 22 and the terminal portion 30 of the flexible printed wiring board 3 are arranged to face each other, and the ACF 6 is interposed therebetween, and then they are thermocompression bonded using, for example, a thermocompression bonding tool, thereby collectively connecting the wirings of the terminal portions 20 and 30. As a result, each of the individual wiring 54 and the output wiring 33, and the common wiring 56 and the common communication wiring 37 can be electrically connected. The connection between the flexible printed wiring board 3 and the printed circuit board 4 is the same.

[0037] FIG. 8 is a configuration diagram of a resistance measurement circuit 7 for measuring the resistance of the first wiring portion 57 of the common wiring 56. The resistance measurement is performed on the actuator substrate 22 before connecting the flexible printed wiring board 3, for example, during the manufacturing process of the inkjet head 100. As shown in FIG. 8, a probe 71 is used to measure the resistance of the first wiring portion 57. A plurality of probes 71 can measure each of the wirings 54, 57, and 59 arranged at the terminal portion 20.

[0038] The resistance of the first wiring portion 57 is measured by the four-terminal method. The resistance measurement circuit 7 connects probes 71 connected to a current source 72 to both ends of the first wiring portion 57 as terminals 1 and 2, respectively. The voltage detection circuit 73 is connected to one terminal 1 of the first wiring portion 57 and the monitor terminal 59. The voltage detection circuit 74 is connected to the other terminal 2 of the first wiring portion 57 and the monitor terminal 59. In FIG. 7, the probes 71 connected to the current source 72 are grouped in pairs so that a predetermined current can flow.

[0039] To measure the resistance of the first wiring portion 57, a predetermined current is passed from one terminal 2 to the other terminal 1 of the first wiring portion 57 by the current source 72, and this current is measured and stored. The reason for leading out terminals 1 to 2 from both ends of the first wiring portion 57 is to prevent voltage drops due to current concentration when a large number of actuators 5 are simultaneously driven during printing, and this configuration is also utilized for resistance measurement.

[0040] At the same time, the voltage between terminal 1 of the first wiring portion 57 and the monitor terminal 59, i.e., the detection voltage 1, is measured. At the same time, the voltage between the monitor terminal 59 and terminal 2 of the first wiring portion 57, i.e., the detection voltage 2, is measured. According to Ohm's law, the value obtained by dividing the detection voltage 1 by the current is the resistance value of half of the first wiring portion 57 (the left side of the drawing paper), the value obtained by dividing the detection voltage 2 by the current is the resistance value of half of the first wiring portion 57 (the right side of the drawing paper), and the value obtained by dividing the sum of the detection voltage 1 and the detection voltage 2 by the current is the overall resistance value of the first wiring portion 57. If the number of monitor terminals 59 is increased, the distribution of the wiring resistance can be managed in more detail. It is advisable to manage the wiring formation process of the manufacturing process so that these resistance values fall within a predetermined range.

[0041] That is, as described with reference to FIG. 3, one terminal of each actuator 5 is connected to the individual wiring 54 and is independently driven by each drive driver D of the drive IC 31. The other terminal of each actuator 5 is connected to a common potential via a common wiring 56 (57, 58). If this common potential is constant, the net voltage applied to each actuator 5 is individually controlled for each channel by the output waveform of each drive driver D connected to the individual wiring 54.

[0042] However, in reality, since the common wiring 56 (57, 58) has resistance, a current flows through the common wiring 56 (57, 58) when driving each actuator 5. In particular, the resistance of the first wiring portion 57 causes a voltage drop when the charge and discharge currents from each actuator 5 concentrate. Since this voltage drop varies depending on which channel is being driven, a phenomenon called crosstalk occurs in which the ejection characteristics of each channel change depending on the printing pattern in the inkjet head 100, deteriorating the printing quality. To prevent this, it is necessary to manage the resistance of the first wiring portion 57 to a low value in particular. For management, it is necessary to measure the resistance.

[0043] Also, the resistance of the first wiring portion 57 is not necessarily uniformly formed. When the common wiring 56 (57, 58) is formed by wet chemical plating, depending on the state of the plating phase, there may be a place where the plating is thick and the resistance is low and a place where the plating is thin and the resistance is high. Therefore, it is desirable to grasp the distribution of the resistance of the first wiring portion 57 simultaneously with the measurement of the resistance.

[0044] Therefore, if the configuration is such that the resistance can be measured as described above, for example, by measuring the voltage waveform of the monitor terminal 59 during driving, it is possible to confirm to what extent the voltage drop due to the resistance of the first wiring portion 57 affects the net waveform applied to the actuator 5. Also, as shown in FIG. 9, a monitor terminal 38 and a monitor pad 39 may be provided on the flexible printed wiring board 3, and the monitor terminal 59 of the actuator substrate 22 and the monitor terminal 38 may be connected by the ACF 6. This is because if there is a monitor pad 38 on the flexible printed wiring board 3, probing for confirming the net waveform becomes easy. The monitor pad 38 may usually be covered with a resist on the flexible printed wiring board 3 in order to prevent a short circuit in the normal state. In that case, the resist may be peeled off at the time of confirming the net waveform to make contact. Also, the process management of the manufacturing process of the inkjet head 100 can be performed.

[0045] Furthermore, the measurement circuit in FIG. 8 measures whether each actuator 5 is normal or not. The capacitance measurement circuit 75 measures the capacitance of each actuator 5 by measuring the waveform of the current flowing through the probe 71 when a predetermined voltage waveform is applied through each probe 71. Then, based on the measured capacitance, it is determined whether each actuator 5 is normal and whether the wiring pattern of each individual wiring 54 is normal. If the contact pins of the probe 71 are provided at each of the terminal 1, terminal 2, and monitor terminal 59 of the first wiring portion 57 and each individual wiring 54, and these are probed collectively, both the resistance measurement of the first wiring portion 57 and the capacitance measurement of the actuator 5 can be performed by switching only the circuit with a single probing and positioning, thereby shortening the inspection time. In that case, for the resistance measurement of the first wiring portion 57, the terminal 1, terminal 2, and monitor terminal 59 of the first wiring portion 57 are used, and the capacitance measurement of the actuator 5 is performed between at least any one of the terminal 1, terminal 2, and monitor terminal 59 of the first wiring portion 57 and each individual wiring 54. If the resistance measurement of the first wiring portion 57 and the capacitance measurement of the actuator 5 are performed simultaneously, the measurement time can be further shortened, but the measurement result of the capacitance measurement is more accurate when the circuit is switched and executed separately.

[0046] According to the above-described embodiment, by providing the monitor terminal 59 on the actuator substrate 22, it becomes possible to measure the resistance of the first wiring portion 57 that applies a common potential to the plurality of actuators 5.

[0047] Note that the inkjet head 100 is not limited to the shear mode type actuator 5 in which the pressure chamber 51 and the air chamber 52 are alternately arranged. For example, a configuration in which a plurality of both the nozzles 25 and the actuators 5 are arranged on the surface of the nozzle plate 21 may be adopted. Other drop-on-demand piezo type actuators 5 may also be used.

[0048] In the above-described embodiment, the inkjet head 100 of the inkjet printer 10 has been described as an example of the liquid ejection device. However, the liquid ejection device may be a shaping material ejection head of a 3D printer or a sample ejection head of a dispensing device.

[0049] Embodiments of the present invention are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the gist of the invention. These embodiments and their modifications are included in the scope and gist of the invention and are included in the invention described in the claims and the equivalent scope thereof.

Explanation of Reference Numerals

[0050] 10 Inkjet printer 100 to 103 Inkjet heads 22 Actuator substrate 25 Nozzle 5 Actuator 54 Individual wiring 56 Common wiring 57 First wiring portion 58 Second wiring portion 59 Monitor terminal D Drive driver (drive circuit)

Claims

1. A plurality of actuators arranged on a substrate, a plurality of individual wirings respectively connected to one terminal of each of the actuators and formed up to a terminal portion on one edge side of the substrate, a first wiring portion formed on the other edge side of the substrate in the arrangement direction of the actuators, and a pair of terminals drawn out from both sides in the arrangement direction of the actuators formed up to one edge side of the substrate, and a common wiring including a plurality of second wiring portions branched from the first wiring portion and connected to the other terminals of the actuators, A liquid discharge head comprising a monitor terminal disposed in the middle of the pair of terminals of the first wiring portion on one edge side of the substrate and connected to the first wiring portion.

2. The liquid discharge head according to claim 1, wherein the monitor terminal is connected to the first wiring portion via any one of the second wiring portions.

3. The liquid discharge head according to claim 1 or 2, wherein the monitor terminal is formed across the arrangement of the plurality of actuators and further through between two adjacent ones of the individual wirings up to the terminal portion.

4. The liquid discharge head according to any one of claims 1 to 3, wherein the monitor terminal is connected to the center in the length direction of the first wiring portion.

5. The liquid discharge head according to any one of claims 1 to 4, wherein the monitor terminal is used for measuring the resistance of the first wiring portion.

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