Liquid jet head and liquid jet apparatus

Abstract

To suppress failure of an integrated circuit mounted on a wiring substrate, even when static electricity is transmitted to the wiring substrate of a liquid jet head.SOLUTION: A liquid jet head comprises: a liquid jet section having a plurality of nozzles that jet liquid and a plurality of drive elements for jetting liquid from the nozzles; a conductive head cover that exposes the plurality of nozzles to the outside; and a wiring substrate on which an integrated circuit is mounted. The wiring substrate has first ground wiring that is electrically connected to the head cover without being electrically connected to electrodes of the drive elements, and second ground wiring that is electrically connected to the integrated circuit. The first ground wiring and the second ground wiring are electrically separated from each other within the wiring substrate.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to a liquid ejection head and a liquid ejection apparatus. [Background technology]

[0002] Conventionally, liquid jet heads that include a wiring board on which an integrated circuit is mounted and that jet a liquid such as ink have been provided. To operate the integrated circuit, it is necessary to set a ground, which is a reference potential. For example, Patent Document 1 discloses a liquid jet head in which a screw that functions as a ground for the liquid jet head is electrically connected to a ground portion of a printed circuit board via a coil spring made of a conductive material. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-88629 Summary of the Invention [Problem to be solved by the invention]

[0004] In a liquid jet head, static electricity can be transmitted to the jetting surface from the medium, etc. In conventional liquid jet heads, static electricity transmitted to the jetting surface can be transmitted to the wiring board of the liquid jet head, which can cause damage to the integrated circuits mounted on the wiring board. [Means for solving the problem]

[0005] A preferred aspect of the present invention provides a liquid ejection head comprising: a liquid ejection unit having a plurality of nozzles for ejecting liquid and a plurality of drive elements for ejecting liquid from the plurality of nozzles; a conductive head cover for exposing the plurality of nozzles to the outside; and a wiring board on which an integrated circuit is mounted; wherein the wiring board has a first ground wiring that is not electrically connected to the electrodes of the drive elements but is electrically connected to the head cover, and a second ground wiring that is electrically connected to the integrated circuit, and the first ground wiring and the second ground wiring are electrically isolated from each other within the wiring board.

[0006] Furthermore, a preferred aspect of the present invention provides a liquid ejection device including the above-described liquid ejection head, and a frame ground electrically connected to at least one of the first ground wiring and the second ground wiring of the liquid ejection head, or a generation circuit that generates, from a power supply, a signal of a reference potential VBS that flows through at least one of the first ground wiring and the second ground wiring of the liquid ejection head that constitutes part of a signal ground. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a schematic diagram showing an example of the configuration of a liquid ejection device 100. FIG. [Figure 2] FIG. 2 is an exploded perspective view of a head module 9. [Figure 3] FIG. 2 is an exploded perspective view of the liquid jet head 200. [Figure 4] FIG. 2 is a cross-sectional view showing an example of the configuration of a head chip 220. [Figure 5] FIG. 10 is an enlarged cross-sectional view of the vicinity of a piezoelectric element 220f. [Figure 6] FIG. [Figure 7] 7 is a cross-sectional view taken along line VII-VII in FIG. 6. [Figure 8] FIG. 10 is a diagram illustrating a wiring board 240A according to a first modified example. [Figure 9] FIG. 10 is a diagram illustrating a head module 9B according to a second modified example. [Figure 10]FIG. 10 is a diagram illustrating a wiring substrate 240C according to a third modified example. DETAILED DESCRIPTION OF THE INVENTION

[0008] 1. First embodiment Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, in each drawing, the dimensions and scale of each part are appropriately different from those of the actual parts. Furthermore, since the embodiments described below are preferred specific examples of the present invention, various technically preferable limitations are applied, but the scope of the present invention is not limited to these embodiments unless otherwise specified in the following description to the effect that the present invention is limited.

[0009] For convenience, the following description will use the mutually intersecting X-axis, Y-axis, and Z-axis as appropriate. Furthermore, one direction along the X-axis is the X1 direction, and the direction opposite to the X1 direction is the X2 direction. Similarly, the Y1 direction and the Y2 direction are opposite directions along the Y-axis. Furthermore, the Z1 direction and the Z2 direction are opposite directions along the Z-axis. Here, the Z-axis is typically a vertical axis, and the Z2 direction corresponds to the downward direction in the vertical direction. In other words, the Z2 direction is the direction of gravity.

[0010] 1-1. Overview of the liquid ejection device 100 1 is a schematic diagram showing an example of the configuration of a liquid ejection device 100. The liquid ejection device 100 is an inkjet printing device that ejects ink, an example of a liquid, as droplets onto a medium PP. The medium PP is, for example, printing paper, but any printing target such as a resin film or fabric can also be used as the medium PP.

[0011] As shown in FIG. 1, the liquid ejection device 100 includes a power supply circuit 2, a drive signal generation circuit 3, a liquid container 14, a memory unit 5, a control unit 6, a moving mechanism 7, a conveying mechanism 8, and a head module 9 having multiple liquid ejection heads 200.

[0012] The liquid container 14 is a container that stores ink. Specific examples of the liquid container 14 include a cartridge that is detachable from the liquid ejection device 100, a bag-shaped ink pack made of flexible film, and an ink tank that can be refilled with ink. The type of ink stored in the liquid container 14 is arbitrary.

[0013] The storage unit 5 is one or more storage circuits such as semiconductor memories. The semiconductor memories are, for example, non-volatile memories such as flash memories. However, the storage unit 5 may also have volatile memories such as RAM. RAM is an abbreviation for Random Access Memory. The storage unit 5 stores various programs and various data.

[0014] The control unit 6 is, for example, one or more processing circuits such as a CPU, SoC, ASIC, or FPGA. CPU is an abbreviation for Central Processing Unit. SoC is an abbreviation for System-on-a-chip. ASIC is an abbreviation for Application Specific Integrated Circuit. FPGA is an abbreviation for Field Programmable Gate Array. The control unit 6 executes programs stored in the memory unit 5 and performs various controls by appropriately using the data.

[0015] The transport mechanism 8 transports the medium PP in the Y2 direction under the control of the control unit 6. In the example shown in Fig. 1, the transport mechanism 8 includes a long transport roller along the X axis and a motor that rotates the transport roller. Note that the transport mechanism 8 is not limited to a configuration using a transport roller, and may be configured, for example, to use a drum or endless belt that transports the medium PP while adsorbed to the outer peripheral surface by electrostatic force or the like.

[0016] The movement mechanism 7 reciprocates the liquid ejection head 200 in the X1 direction and the X2 direction under the control of the control unit 6. In this embodiment, the X1 direction and the X2 direction are main scanning directions, and the Y2 direction is the sub-scanning direction. As such, the liquid ejection device 100 in the first embodiment is a serial type liquid ejection device that reciprocates along the X axis. As shown in FIG. 1, the movement mechanism 7 includes a carriage 71 that houses the head module 9, an endless belt 72 to which the carriage 71 is fixed, and a carriage motor (not shown) that is a drive source for reciprocating the carriage 71.

[0017] The head module 9 ejects ink supplied from the liquid container 14 in the Z2 direction under the control of the control unit 6. The head module 9 has one or more liquid ejecting heads 200 mounted thereon.

[0018] The control unit 6 drives the piezoelectric element 220f (described later) to eject ink from the nozzle N. Specifically, the control unit 6 generates a designation signal SI for controlling the liquid ejection head 200, a signal for controlling the power supply circuit 2, a waveform designation signal dCom for controlling the drive signal generation circuit 3, a signal for controlling the transport mechanism 8, a signal for controlling the movement mechanism 7, and the like.

[0019] The power supply circuit 2 receives power from a commercial power supply (not shown) and generates signals of various predetermined potentials. The generated potentials are supplied to each section of the liquid ejection device 100 as appropriate. For example, the power supply circuit 2 generates a power supply potential signal VHV1, which is a signal of the power supply potential VHV, and a reference potential signal VBS1, which is a signal of the reference potential VBS. The reference potential signal VBS1 is supplied to the head module 9. The power supply potential signal VHV1 is also supplied to the drive signal generation circuit 3. The power supply circuit 2 is an example of a "generation circuit."

[0020] The waveform specification signal dCom is a digital signal that defines the waveform of the drive signal Com. The drive signal Com is an analog signal for driving the piezoelectric element 220f, which will be described later in FIG. 4. The drive signal generation circuit 3 generates the drive signal Com having a waveform defined by the waveform specification signal dCom based on the power supply potential signal VHV1. Specifically, the drive signal generation circuit 3 includes, for example, a DA conversion circuit and an amplifier circuit. In the drive signal generation circuit 3, the DA conversion circuit converts the waveform specification signal dCom from the control unit 6 from a digital signal to an analog signal, and the amplifier circuit amplifies the analog signal using the power supply potential signal VHV1 from the power supply circuit 2, thereby generating the drive signal Com. The piezoelectric element 220f is an example of a "drive element."

[0021] The specification signal SI is a digital signal for specifying the type of operation of the piezoelectric element 220f. Specifically, the specification signal SI specifies whether or not to supply the drive signal Com to the piezoelectric element 220f, thereby specifying the type of operation of the piezoelectric element 220f. Here, specifying the type of operation of the piezoelectric element 220f means, for example, specifying whether or not to drive the piezoelectric element 220f, or specifying whether or not ink is ejected from the piezoelectric element 220f when the piezoelectric element 220f is driven.

[0022] When the control unit 6 receives a print instruction from a host computer such as a personal computer or a digital camera, it first stores the print data Img included in the print instruction in the storage unit 5. Next, the control unit 6 generates various control signals, such as a designation signal SI, a waveform designation signal dCom, a signal for controlling the transport mechanism 8, and a signal for controlling the movement mechanism 7, based on various data such as the print data Img stored in the storage unit 5. Then, based on the various control signals and various data stored in its own memory circuit, the control unit 6 controls the transport mechanism 8 and the movement mechanism 7 to change the relative position of the medium PP with respect to the liquid ejection head 200, while controlling the liquid ejection head 200 to drive the piezoelectric element 220f. In this way, the control unit 6 adjusts whether or not ink is ejected from the piezoelectric element 220f, the amount of ink ejected, the ink ejection timing, and the like, and controls the execution of a printing operation to form an image corresponding to the print data Img on the medium PP.

[0023] 1-2. Head module 9 Fig. 2 is an exploded perspective view of the head module 9. In Fig. 2, in order to prevent the drawing from becoming too complicated, the shape of the liquid jet head 200 is shown in a simplified form. The head module 9 has a plurality of liquid jet heads 200, a base 91, a distribution flow path member 93, and a base cover 95.

[0024] The base 91 is a member that holds the multiple liquid jet heads 200. The base 91 is provided with a space that is open in the Z2 direction, and this space accommodates the multiple liquid jet heads 200. The base 91 is made of a conductive material such as metal.

[0025] In the example of Figures 1 and 2, six liquid jet heads 200 are held on the base 91, but the number of liquid jet heads 200 is not particularly limited and may be one, or two or more.

[0026] The base 91 is also provided with supply holes 911 that penetrate along the Z axis. The flow paths of the liquid jet head 200 fixed to the base 91 are exposed on a surface facing the Z1 direction by the supply holes 911, and the distribution flow path member 93 is connected to the flow paths exposed by the supply holes 911.

[0027] The base 91 is also provided with wiring member openings 913 for inserting the wiring members 244 of the liquid jet head 200. In this embodiment, one wiring member opening 913 is provided at the end in the Y1 direction and one wiring member opening 913 is provided at the end in the Y2 direction for each liquid jet head 200. That is, a total of two wiring member openings 913 are provided for each liquid jet head 200. The wiring members 244 of the liquid jet head 200 fixed in the space of the base 91 via such wiring member openings 913 are led out in the Z1 direction of the base 91.

[0028] A relay substrate 97 is attached to each of the wall surfaces of the base 91 facing the Y1 direction and the Y2 direction. A wiring member 244 is electrically connected to the relay substrate 97. In this embodiment, the relay substrate 97 has a length that spans multiple liquid jet heads 200 along the X axis, six in this embodiment. The two relay substrates 97 are also arranged side by side along the Y axis.

[0029] The relay substrate 97 also has a connector 971 to which a control cable 6a from the control unit 6 is detachably connected. In this embodiment, one control cable 6a is connected to each relay substrate 97. The number of control cables 6a is not limited and may be two or more. The control cable 6a is formed of a flexible substrate. The control cable 6a is, for example, a flexible substrate such as COF, FPC, or FFC. COF is an abbreviation for Chip On Film. FPC is an abbreviation for Flexible Printed Circuits. FFC is an abbreviation for Flexible Flat Cable.

[0030] The distribution flow path member 93 is a member that distributes and supplies the ink supplied from the liquid container 14 to each liquid jet head 200. Inside the distribution flow path member 93 (not shown), distribution flow paths are provided that distribute and supply the ink of each color or type supplied from the liquid container 14 to the liquid jet heads 200.

[0031] The base cover 95 is provided with a control cable opening 953 for inserting the control cable 6a. The control cable 6a is inserted through the control cable opening 951 and connected to an internal relay board 97. In this embodiment, the base cover 95 is formed of a conductive material such as metal. The base cover 95 is fixed to the base 91 by a conductive screw member 955 such as metal. The base cover 95 is connected to the housing of the liquid ejection device 100 by a conductive metal spring (not shown).

[0032] 1-3. Configuration of the liquid jet head 200 3 is an exploded perspective view of the liquid jet head 200. The liquid jet head 200 has a head cover 210, six head chips 220, six drive circuits 221, a holder 230, a wiring board 240, and a flow path member 250. As shown in FIG. 3, the head cover 210, the six head chips 220, the holder 230, the wiring board 240, and the flow path member 250 are stacked in this order along the Z axis. The six head chips 220 correspond to a "liquid jet unit."

[0033] One head chip 220 has a plurality of nozzles N. In this embodiment, the plurality of nozzles N that one head chip 220 has constitutes two nozzle rows. However, the number of head chips 220 that the liquid jet head 200 has is not limited to six, as long as it is two or more. Furthermore, the number of nozzle rows that the head chip 220 has is not limited to two, and may be one. The head chip 220 will be described with reference to FIG. 4.

[0034] Fig. 4 is a cross-sectional view showing an example of the configuration of the head chip 220. However, in Fig. 4, in addition to the head chip 220, a drive circuit 221 and a part of the head cover 210 are also shown.

[0035] As shown in Fig. 4, head chip 220 has a plurality of nozzles N arranged in the direction along the Y axis. The plurality of nozzles N are divided into two nozzle rows arranged at intervals in the direction along the X axis, as shown in Fig. 4. Each of the two nozzle rows is a collection of nozzles N arranged linearly in the direction along the Y axis.

[0036] The head chips 220 are configured to be approximately symmetrical to each other in the direction along the X axis, but the positions of the nozzles N in one of the two nozzle rows and the nozzles N in the other nozzle row in the direction along the Y axis may or may not match.

[0037] As shown in FIG. 4, the head chip 220 has a flow path substrate 220a, a pressure chamber substrate 220b, a nozzle plate 220c, a vibration absorber 220d, a vibration plate 220e, a plurality of piezoelectric elements 220f, a protective plate 220g, a case 220h, and a wiring member 220i.

[0038] The flow path substrate 220a and the pressure chamber substrate 220b are stacked in this order in the Z1 direction to form a flow path for supplying ink to the multiple nozzles N. In an area located further in the Z1 direction than the stack consisting of the flow path substrate 220a and the pressure chamber substrate 220b, a vibration plate 220e, multiple piezoelectric elements 220f, a protective plate 220g, a case 220h, and a wiring member 220i are installed. On the other hand, in an area located further in the Z2 direction than the stack, a nozzle plate 220c and a vibration absorber 220d are installed. Each element of the head chip 220 is roughly a plate-like member that is elongated in the Y direction, and is joined to each other by, for example, an adhesive. Each element of the head chip 220 will be described in order below.

[0039] The nozzle plate 220c is a plate-like member provided with a plurality of nozzles N. Each of the plurality of nozzles N is a through-hole that allows ink to pass through. Here, the surface of the nozzle plate 220c facing the Z2 direction is the nozzle surface FN. The nozzle plate 220c is manufactured by processing a silicon single crystal substrate using semiconductor manufacturing techniques such as dry etching or wet etching. However, other known methods and materials may also be used as appropriate for manufacturing the nozzle plate 220c. Furthermore, the cross-sectional shape of the nozzle N is typically circular, but is not limited thereto and may be a non-circular shape such as a polygonal or elliptical shape.

[0040] The flow path substrate 220a is provided with a space R1, a plurality of supply flow paths Ra, and a plurality of communication flow paths Na for each of the two nozzle rows. The space R1 is an elongated opening extending in the direction along the Y axis in a plan view seen in the direction along the Z axis. Each of the supply flow paths Ra and the communication flow paths Na is a through hole formed for each nozzle N. Each supply flow path Ra communicates with the space R1.

[0041] The pressure chamber substrate 220b is a plate-like member in which a plurality of pressure chambers CV, called cavities, are provided for each of the two nozzle rows. The plurality of pressure chambers CV are arranged in a direction along the Y axis. Each pressure chamber CV is formed for each nozzle N and is an elongated space extending in a direction along the X axis in a plan view. Like the nozzle plate 220c described above, the flow path substrate 220a and the pressure chamber substrate 220b are each manufactured by processing a silicon single crystal substrate using semiconductor manufacturing technology, for example. However, other known methods and materials may also be used as appropriate to manufacture the flow path substrate 220a and the pressure chamber substrate 220b.

[0042] The pressure chambers CV are spaces located between the flow path substrate 220a and the vibration plate 220e. For each of the two nozzle rows, a plurality of pressure chambers CV are arranged in the direction along the Y axis. The pressure chambers CV are also connected to the communication flow paths Na and the supply flow paths Ra. Therefore, the pressure chambers CV are connected to the nozzles N via the communication flow paths Na, and to the space R1 via the supply flow paths Ra.

[0043] A diaphragm 220e is disposed on the surface of the pressure chamber substrate 220b facing the Z1 direction. The diaphragm 220e is a plate-like member that can vibrate elastically. The diaphragm 220e has, for example, a first layer and a second layer, which are stacked in this order in the Z1 direction. The first layer is, for example, an elastic film made of silicon oxide. The elastic film is formed, for example, by thermally oxidizing one surface of a silicon single crystal substrate. The second layer is, for example, an insulating film made of zirconium oxide. The insulating film is formed, for example, by forming a zirconium layer by sputtering and then thermally oxidizing the layer. Note that the diaphragm 220e is not limited to a configuration formed by stacking the first and second layers described above, and may be, for example, a single layer or three or more layers.

[0044] On the surface of the vibration plate 220e facing the Z1 direction, a plurality of piezoelectric elements 220f corresponding to the nozzles N in each of the two nozzle rows are arranged. Each piezoelectric element 220f is a passive element that deforms when a drive signal Com is supplied. Each piezoelectric element 220f has an elongated shape extending in the direction along the X axis in a plan view. The plurality of piezoelectric elements 220f are arranged in the direction along the Y axis so as to correspond to the plurality of pressure chambers CV. The piezoelectric elements 220f overlap the pressure chambers CV in a plan view.

[0045] Fig. 5 is an enlarged cross-sectional view of the vicinity of the piezoelectric element 220f, but in Fig. 5, the protection plate 220g is omitted to avoid complication of the drawing.

[0046] 5, the piezoelectric element 220f is a laminated body in which a piezoelectric body Zm is interposed between an upper electrode Zu to which a reference potential signal VBS1 is supplied and a lower electrode Zd to which a drive signal Com is supplied. When viewed from the Z1 direction, for example, the piezoelectric element 220f is a portion where the lower electrode Zd, the upper electrode Zu, and the piezoelectric body Zm overlap. A pressure chamber CV is provided in the Z2 direction of the piezoelectric element 220f. While the first embodiment illustrates a configuration in which the reference potential signal VBS1 is supplied to the upper electrode Zu and the drive signal Com is supplied to the lower electrode Zd, a configuration in which the drive signal Com is supplied to the upper electrode Zu and the reference potential signal VBS1 is supplied to the lower electrode Zd may also be used.

[0047] Returning to Fig. 4 for the explanation, protective plate 220g is a plate-like member placed on the surface of diaphragm 220e facing the Z1 direction, and protects the multiple piezoelectric elements 220f and reinforces the mechanical strength of diaphragm 220e. Here, the multiple piezoelectric elements 220f are housed between protective plate 220g and diaphragm 220e. Protective plate 220g is made of, for example, a resin material.

[0048] The case 220h is a member for storing ink to be supplied to the multiple pressure chambers CV. The case 220h is made of, for example, a resin material. The case 220h is provided with a space R2 for each of the two nozzle rows. The space R2 is a space that communicates with the aforementioned space R1, and together with the space R1, functions as a reservoir R that stores ink to be supplied to the multiple pressure chambers CV. The case 220h is provided with an inlet IH for supplying ink to each reservoir R. The ink in each reservoir R is supplied to the pressure chamber CV via each supply flow path Ra.

[0049] The vibration absorber 220d, also called a compliance substrate, is a flexible resin film that forms the wall surface of the reservoir R and absorbs pressure fluctuations of the ink inside the reservoir R. The vibration absorber 220d may also be a flexible thin metal plate. The surface of the vibration absorber 220d facing the Z1 direction is bonded to the flow path substrate 220a with an adhesive or the like.

[0050] The wiring member 220i is mounted on the surface of the diaphragm 220e facing the Z1 direction, and is a mounting component for electrically connecting the head chip 220 with the drive circuit 221, the control unit 6, etc. The wiring member 220i is, for example, a flexible wiring board such as COF, FPC, or FFC. The above-mentioned drive circuit 221 is mounted on the wiring member 220i of this embodiment. COF is an abbreviation for Chip On Film. FPC is an abbreviation for Flexible Printed Circuit. FFC is an abbreviation for Flexible Flat Cable. The wiring member 220i electrically connects the piezoelectric element 220f and the wiring board 240.

[0051] The drive circuit 221 drives the plurality of piezoelectric elements 220f under the control of the control unit 6. The drive circuit 221 includes a switching element that switches whether or not the drive signal Com is supplied to each of the plurality of piezoelectric elements 220f.

[0052] Returning to Fig. 3 for the explanation, the head cover 210 is a member for exposing the multiple nozzles N to the outside. As shown in Fig. 3, the head cover 210 is made of a conductive member formed from a conductive material such as metal, for example, a plate-shaped member formed from stainless steel.

[0053] One head cover 210 is provided in common to the multiple head chips 220. Of course, the head cover 210 is not limited to a configuration in which it is provided in common to all of the head chips 220 provided in one liquid jet head 200, and may be provided independently for each head chip 220, or may be provided independently for each group made up of two or more multiple head chips 220. However, as in the present embodiment, by providing the head cover 210 in common to all of the head chips 220 constituting one liquid jet head 200 and fixing the head chips 220 to the head cover 210, the head cover 210 can be used to perform relative positioning of the nozzle openings of the multiple head chips 220, and it is possible to perform highly accurate positioning of the nozzle surfaces FN of the multiple head chips 220 in the direction along the Z axis.

[0054] The head cover 210 is provided with exposure openings 211 for exposing the multiple nozzles N to the outside. In this embodiment, the exposure openings 211 are provided so as to open independently for each head chip 220. The liquid jet head 200 of this embodiment has six head chips 220, and therefore six independent exposure openings 211 are provided. However, depending on the configuration of the head chips 220, one common exposure opening 211 may be provided for a group made up of multiple head chips 220. The surface of the head cover 210 facing the Z2 direction is the surface that faces the medium PP. Hereinafter, the surface of the head cover 210 facing the Z2 direction may be referred to as the ejection surface SN. The ejection surface SN may include the nozzle surface FN.

[0055] Holder 230 is fixed to a surface facing the Z2 direction of flow path member 250. Holder 230 forms a groove-shaped space facing the Z2 direction. Within this space, multiple head chips 220 are arranged side by side along the X axis.

[0056] The holder 230 is provided with first wiring member openings 231 for inserting the respective wiring members 220i of the six head chips 220. The first wiring member openings 231 are provided so as to open independently for each wiring member 220i. The liquid jet head 200 of this embodiment has six head chips 220, and therefore six independent first wiring member openings 231 are provided. However, depending on the configuration of the head chips 220, one common first wiring member opening 231 may be provided for a group made up of a plurality of head chips 220.

[0057] Furthermore, holder 230 is provided with four connection pipes 233 on its surface facing the Z1 direction. Connection pipes 233 are tubular bodies protruding from the surface facing the Z1 direction. Connection pipes 233 are provided with flow paths for supplying ink supplied from liquid container 14 to head chip 220. Although not present in this embodiment, connection pipes 233 may also be provided with flow paths for discharging ink from head chip 220.

[0058] The wiring board 240 is a mounting component for electrically connecting the liquid jet head 200 to the control unit 6. An integrated circuit 241 is mounted on a surface of the wiring board 240 facing the Z1 direction. The integrated circuit 241 is, for example, a memory, but may be a device other than a memory. Furthermore, the wiring board 240 is provided with second wiring member openings 242a for inserting the wiring members 220i. In the present embodiment, the wiring board 240 is provided with two second wiring member openings 242a, namely, second wiring member openings 242a_1 and second wiring member openings 242a_2, and two wiring members 220i are inserted into one second wiring member opening 242a. The second wiring member opening 242a_1 is positioned in the X2 direction relative to the second wiring member openings 242a_2.

[0059] The wiring board 240 also has two connectors 243, connector 243_1 and connector 243_2, on its surface facing the Z1 direction. The connector 243_1 is provided at an end of the wiring board 240 in the Y1 direction. The connector 243_2 is provided at an end of the wiring board 240 in the Y2 direction. A wiring member 244_1 is detachably connected to the connector 243_1. A wiring member 244_2 is detachably connected to the connector 243_2. Hereinafter, the connectors 243_1 and 243_2 may be referred to as connectors 243 without distinction. The two wiring members 244 are formed of flexible substrates. A more detailed description of the wiring board 240 will be given later.

[0060] Flow path member 250 has a flow path provided inside (not shown) that supplies ink supplied from distribution flow path member 93 to head chip 220. This flow path is provided on a surface of flow path member 250 facing the Z1 direction, and is opened to the tip surface of protrusion 251 protruding in the Z1 direction. In this embodiment, four protrusions 251 are provided on the surface of flow path member 250 facing the Z2 direction. A filter may be provided midway along the flow path inside flow path member 250 to remove foreign matter such as dust and air bubbles contained in the ink.

[0061] Furthermore, the flow path member 250 is provided with cable insertion holes 252 that penetrate along the Z axis at each of the Y1-direction end and the Y2-direction end. A wiring member 244 is inserted through the cable insertion holes 252 from the Z2 direction of the flow path member 250 and is connected to the wiring board 240 held between the flow path member 250 and the holder 230. The two wiring members 244 are formed from flexible boards. The wiring members 244 are flexible boards such as COF, FPC, or FFC, for example.

[0062] 1-4. Static electricity generated during printing When a printing operation is performed, static electricity may be transmitted from the medium PP to the ejection surface SN. The static electricity transmitted to the ejection surface SN may be transmitted to the integrated circuit 241 of the wiring board 240 via the head cover 210, which may cause the integrated circuit 241 to malfunction.

[0063] Therefore, in this embodiment, the wiring board 240 has a ground wiring GND1 for grounding electrically connected to the head cover 210 and a normal ground wiring GND2 electrically connected to the integrated circuit 241. The ground wiring GND1 and the normal ground wiring GND2 are characterized by being electrically isolated from each other within the wiring board 240. The ground wiring GND1 for grounding is an example of a "first ground wiring." The normal ground wiring GND2 is an example of a "second ground wiring."

[0064] In this specification, "component 1 and component 2 are electrically connected" means that component 1 and component 2 are directly connected in a conductive state, or that component 1 and component 2 are indirectly connected via a conductor in a conductive state. Furthermore, "component 1 and component 2 are electrically isolated" means that component 1 and component 2 are not electrically connected. However, if component 1 and component 2 are indirectly connected via a conductor and the volume of this conductor is sufficiently large so that component 1 and component 2 have almost no mutual influence, component 1 and component 2 are considered to be electrically isolated. Specifically, "component 1 and component 2 have almost no mutual influence" means that a change in current through component 1 causes almost no change in the potential of component 2, and that a change in current through component 2 causes almost no change in the potential of component 1. Furthermore, "almost no change in potential" includes not only complete no change in potential, but also cases where the potential can be considered to be almost no change, taking into account error. Below, the wiring substrate 240 will be described using Figures 6 and 7.

[0065] 1-5. Configuration of wiring board 240 FIG. 6 is an exploded perspective view of the wiring board 240. FIG. 7 is a cross-sectional view taken along line VII-VII in FIG. 6. Line VII-VII is a line segment parallel to the X-axis. In addition to the wiring board 240, FIG. 7 also shows a portion of the holder 230, a portion of the head cover 210, and a portion of the base 91. When viewed along the Z-axis, the wiring board 240 has a substantially rectangular shape. The Z-axis direction is also the thickness direction of the wiring board 240. As shown in FIGS. 6 and 7, the wiring board 240 is configured by stacking a first insulator layer 245a, a second insulator layer 245b, a third insulator layer 245c, and a fourth insulator layer 245d in this order along the Z-axis. In the following description, the first insulator layer 245a, the second insulator layer 245b, the third insulator layer 245c, and the fourth insulator layer 245d may be referred to as insulator layers 245 without distinction. The four insulator layers 245 may be formed of one type of insulator, or may be formed of two or more types of insulators. The wiring board 240 is a multilayer board having four insulator layers 245. The number of insulator layers 245 included in the wiring board 240 is not limited to four, as long as it is three or more. The four insulator layers 245 are an example of "three or more insulator layers."

[0066] The wiring board 240 has an integrated circuit 241, two second wiring member openings 242a, two connectors 243, as well as six terminal groups 246, twelve or more signal wirings SL, a ground wiring GND1 for grounding, a normal ground wiring GND2, and four flow path openings 247.

[0067] The six terminal groups 246 are directly connected to terminals of the wiring member 220i in the Z1 direction in a conductive state. The six terminal groups 246 are provided on a surface of the first insulator layer 245a facing the Z1 direction. The six terminal groups 246 include a terminal group 246_1, a terminal group 246_2, a terminal group 246_3, a terminal group 246_4, a terminal group 246_5, and a terminal group 246_6. Two of the six terminal groups 246 are arranged along the X1-direction side and the X2-direction side of the wiring board 240, and the remaining four terminal groups 246 are arranged along the X1-direction side and the X2-direction side of each of the two second wiring member openings 242a. Specifically, the terminal group 246_1 is arranged along the X2-direction side of the wiring board 240. The terminal group 246_2 is arranged along the side of the second wiring member opening 242a_1 in the X2 direction. The terminal group 246_3 is arranged along the side of the second wiring member opening 242a_1 in the X1 direction. The terminal group 246_4 is arranged along the side of the second wiring member opening 242a_2 in the X2 direction. The terminal group 246_5 is arranged along the side of the second wiring member opening 242a_1 in the X1 direction. The terminal group 246_6 is arranged along the side of the wiring board 240 in the X2 direction.

[0068] The 12 or more signal wirings SL are wirings for transmitting electrical signals between the respective components of the wiring board 240. The 12 or more signal wirings SL include, for example, signal wirings SL1_i and signal wirings SL2_i, where i is an integer from 1 to 6. The signal wirings SL1_i are wirings for transmitting electrical signals between one or more terminals of the terminal group 246_i and the integrated circuit 241. The signal wirings SL2_i are wirings for transmitting electrical signals between one or more terminals of the terminal group 246_i and the connector 243_2. The 12 or more signal wirings SL are an example of a "plurality of signal wirings."

[0069] The signal wiring SL of the wiring substrate 240 may be disposed between two adjacent insulator layers 245 out of the four insulator layers 245 .

[0070] The ground wiring GND1 for grounding is a ground wiring for electrically connecting to a frame ground external to the liquid jet head 200. The normal ground wiring GND2 is a wiring for constituting a part of the signal ground. The signal ground is a potential that serves as a reference for operation in an electronic circuit. The frame ground is a potential that is connected to a metal frame part that is the most stable and easy to use as a reference when adjusting potentials between components of a device. The frame ground external to the liquid jet head 200 is, for example, the base 91. In this embodiment, the description will be given assuming that the frame ground external to the liquid jet head 200 is the base 91. The normal ground wiring GND2 may be electrically connected to the frame ground. In other words, the ground ground wiring GND1 and the normal ground wiring GND2 may be indirectly connected via the frame ground. This is because even if they are indirectly connected via the frame ground, the volume of the conductor that serves as the frame ground is sufficiently large to satisfy the condition that the ground wiring GND1 and the normal ground wiring GND2 are electrically isolated from each other.

[0071] The ground wiring GND1 for grounding is provided at the end in the Y2 direction of the wiring board 240. As shown in Figures 6 and 7, in the wiring board 240, the ground wiring GND1 for grounding has a wiring portion GND11, a through-hole wiring GND12, and a wiring portion GND13.

[0072] The wiring portion GND11 is disposed along the X-axis on the surface of the first insulator layer 245a facing the Z1 direction. In FIG. 6, the wiring portion GND11 is shaded with diagonal lines from the upper left to the lower right. The wiring portion GND11 is directly and electrically connected to the ground spring contact portion 248a at its end in the X2 direction. The ground spring contact portion 248a is made of a conductive material. The ground spring contact portion 248a is in contact with the ground spring SP1 disposed along the Z-axis on its surface facing the Z1 direction. The ground spring SP1 is made of a conductive material. Although not shown in FIG. 6, the ground spring SP1 is in contact with the base 91 at its end in the Z1 direction. The wiring portion GND11 is directly and electrically connected to the through-hole wiring GND12 at its end in the X1 direction. The ground spring SP1 is an example of a "conductive member that electrically connects the first ground wiring and the frame ground."

[0073] The through-hole wiring GND12 is arranged along the through-hole 242b that penetrates the wiring board 240, specifically the four insulator layers 245, along the Z-axis. A through-hole is a through-hole that penetrates a multilayer board and is provided to provide electrical continuity between the multiple insulator layers of the multilayer board or between two wires provided on either side of the multilayer board. The through-hole can also be used to insert a lead component. At the end of the through-hole wiring GND12 in the Z2 direction, the through-hole wiring GND12 is directly connected to the wiring portion GND13 in a conductive state.

[0074] The wiring portion GND13 is disposed on the surface of the fourth insulator layer 245d facing the Z2 direction, substantially aligned with the X axis. In FIG. 6, the wiring portion GND13 is not visible because the wiring substrate 240 is viewed in the Z2 direction. However, for convenience, the wiring portion GND13 is depicted by a dashed line. As shown in FIGS. 6 and 7, the end of the wiring portion GND13 in the X1 direction bends in the Y1 direction to avoid the crimping through-hole 242c provided near the vertex of the wiring substrate 240 when viewed along the Z axis. Furthermore, the end of the wiring portion GND13 in the X1 direction is directly connected to the ground spring contact portion 248b in a conductive state. The ground spring contact portion 248b is formed of a conductive material. The ground spring contact portion 248b is disposed on the surface of the fourth insulator layer 245d facing the Z2 direction. In FIG. 6, since the wiring board 240 is viewed in the Z2 direction, the ground spring contact portion 248b is not visible, but for convenience, the ground spring contact portion 248b is shown by a dashed line. The ground spring contact portion 248b contacts the ground spring SP2, which is arranged along the Z axis, on the surface facing the Z2 direction. The ground spring SP2 is made of a conductive material. Although not shown in FIG. 7, the Z2-direction end of the ground spring SP2 contacts the head cover 210.

[0075] 7, the ground spring SP2 abuts against the head cover 210 via the outside of the holder 230, specifically, via the Y2-direction wall surface of the holder 230. Although not shown, the ground spring SP1 also abuts against the base 91 via the outside of the flow path member 250.

[0076] The normal ground wiring GND2 is supplied with a reference potential signal VBS1 supplied from the power supply circuit 2. In FIG. 6, the normal ground wiring GND2 is shaded with diagonal lines from the upper right to the lower left. The reference potential signal VBS1 is an example of a "reference potential signal flowing to the signal ground." The normal ground wiring GND2 is electrically connected to the integrated circuit 241. Furthermore, the normal ground wiring GND2 is electrically connected to the upper electrode Zu of the piezoelectric element 220f. Furthermore, the normal ground wiring GND2 is electrically connected to the drive circuit 221. However, the ground wiring GND1 for earthing is not electrically connected to the drive circuit 221.

[0077] 6, the normal ground wiring GND2 has a wiring portion GND21 having a width D2 that is larger than the width D1 of the ground wiring GND1 for grounding. The maximum width of the normal ground wiring GND2 is larger than the maximum width of the ground wiring GND1 for grounding. In other words, the area of ​​the normal ground wiring GND2 is larger than the area of ​​the ground wiring GND1 for grounding when viewed in the Z-axis direction.

[0078] The ground wiring GND1 for grounding, the 12 or more signal wirings SL, and the normal ground wiring GND2 are preferably arranged at a distance from each other, and vias are also preferably avoided. Specifically, as can be seen from FIG. 6, the ground wiring GND1, the 12 or more signal wirings SL, and the normal ground wiring GND2 do not overlap each other in a planar view. Furthermore, the ground wiring GND1, the 12 or more signal wirings SL, and the normal ground wiring GND2 are adjacent to the ground wiring GND1, and the normal ground wiring GND2 is arranged on the Z1-direction surface of the fourth insulator layer 245d. The shortest distance D1 between the normal ground wiring GND2 and the ground wiring GND1 for grounding is 4 mm or more.

[0079] As shown in FIG. 8 , the wiring substrate 240 has four flow path openings 247. The four flow path openings 247 are through-holes that penetrate along the Z-axis. Specifically, the four flow path openings 247 are provided near the vertices of the wiring substrate 240 in a plan view. The four flow path openings 247 are: a flow path opening 247_1 provided at the end in the X2 direction and the Y1 direction; a flow path opening 247_2 provided at the end in the X2 direction and the Y2 direction; a flow path opening 247_3 provided at the end in the X1 direction and the Y2 direction; and a flow path opening 247_4 provided at the end in the X1 direction and the Y1 direction. As shown in FIG. 6 , the flow path opening 247_2 is disposed between the wiring portion GND11, which is a part of the ground wiring GND1, and the signal wiring SL2_3 in a plan view. The flow path opening 247_2 corresponds to a “through-hole.”

[0080] One of the four connection pipes 233 of the holder 230 is inserted into each of the four flow path openings 247. Specifically, for each integer i from 1 to 4, a connection pipe 233_i is inserted into the flow path opening 247_i. Furthermore, for each integer i from 1 to 4, the space inside the connection pipe 233_i is a connection flow path FP_i that communicates between the six head chips 220 and the flow path member 250. The connection flow path FP_2 is an example of a "connection flow path" that is arranged inside the flow path opening 247_2.

[0081] In this embodiment, the connecting pipes 233 protruding in the Z1 direction are connected to each of the four flow path openings 247, but this is not limiting, and the flow path member 250 may have connecting pipes protruding in the Z2 direction, and these connecting pipes may be inserted into each of the flow path openings 247. Alternatively, the members inserted into each of the four flow path openings 247 may be separate from the flow path member 250 and the holder 230. An example of a member separate from the flow path member 250 and the holder 230 is a spacer that adjusts the distance between the flow path member 250 and the holder 230.

[0082] 7, the signal wiring SL and the normal ground wiring GND2 are not arranged on the layers above and below the ground wiring GND1 for grounding. Also, as can be seen from FIG. 6, the integrated circuit 241 is arranged on the opposite side of the ground wiring GND1 for grounding in a plan view. Specifically, in a plan view, the integrated circuit 241 is arranged in the Y1 direction from the center of gravity G1 of the wiring board 240 in a plan view, while the ground wiring GND1 for grounding is arranged in the Y2 direction from the center of gravity G1. The center of gravity is the point at which the sum of the first moments of area in a target shape becomes zero. By separating the integrated circuit 241 from the ground wiring GND1 for grounding, the integrated circuit 241 can be prevented from being affected by static electricity noise.

[0083] The wiring board 240 also has a signal wiring SL3. The signal wiring SL3 has a wiring portion SL3_1, a through-hole wiring SL3_2, and a wiring portion SL3_3. The wiring portion SL3_1 is a wiring for transmitting an electrical signal between the connector 243_2 of the first insulator layer 245a and the through-hole wiring SL3_2. The through-hole wiring SL3_2 is arranged along the through-hole 242d that penetrates the wiring board 240. The wiring portion SL3_3 is arranged on the Z2-direction surface of the fourth insulator layer 245d. In FIG. 6, since the wiring board 240 is viewed in the Z2 direction, the wiring portion SL3_3 is not visible, but is shown by a dashed line for convenience. As can be seen from FIG. 6, the through-hole wiring SL3_2 is preferably arranged away from the ground wiring GND1.

[0084] 1-6. Pathways through which static electricity is transmitted 7 shows the path RT, which is one of the paths along which static electricity generated on the ejection surface SN travels, up to the base 91. The path RT passes through the head cover 210, the ground spring SP2, the ground spring contact portion 248b, the ground wiring GND1, the ground spring contact portion 248a, and the ground spring SP1, and reaches the base 91, which is the frame ground.

[0085] 1-7. Summary of the first embodiment The liquid jet head 200 in the first embodiment includes six head chips 220 each having a plurality of nozzles N for ejecting ink and a plurality of piezoelectric elements 220f for ejecting ink from the plurality of nozzles N, a conductive head cover 210 for exposing the plurality of nozzles N to the outside, and a wiring board 240 on which an integrated circuit 241 is mounted. The wiring board 240 includes a ground wiring GND1 for grounding that is electrically connected to the head cover 210 but is not electrically connected to the upper electrodes Zu of the piezoelectric elements 220f, and a normal ground wiring GND2 that is electrically connected to the integrated circuit 241. The ground wiring GND1 and the normal ground wiring GND2 are electrically isolated from each other within the wiring board 240. According to the first embodiment, even if static electricity generated in the head cover 210 flows into the ground wiring GND1 for grounding, the static electricity does not reach the normal ground wiring GND2 that is electrically isolated from the ground wiring GND1 for grounding, and therefore, failure of the integrated circuit 241 can be suppressed.

[0086] The wiring board 240 has 12 or more signal wirings SL, and the ground wiring GND1 for grounding, the signal wirings SL, and the normal ground wiring GND2 do not overlap with each other in a plan view. In the first embodiment, the ground wiring GND1 for grounding is arranged farther away from the signal wiring SL and the normal ground wiring GND2 in plan view than in a configuration in which the ground wiring GND1 for grounding is overlapped with the signal wiring SL and the normal ground wiring GND2. Generally, static electricity is a high voltage, and high voltages can cause dielectric breakdown and short circuits. The greater the distance between the two wirings, the less likely the two wirings are to be short-circuited. According to the first embodiment, static electricity can be prevented from flowing into the normal ground wiring GND2 compared to a configuration in which the ground wiring GND1 for grounding is overlapped with the signal wiring SL and the normal ground wiring GND2.

[0087] In plan view, the shortest distance between the ground wiring GND1 and the wiring adjacent to the ground wiring GND1 among the plurality of signal wirings and normal ground wiring GND2 is preferably 4 mm or more. This reduces the influence of static electricity noise on the signal wiring SL and normal ground wiring GND2. More preferably, the shortest distance is 5 mm or more, followed by 6.3 mm or more, 8 mm or more, and 10 mm or more, with the latter being more preferable. According to the first embodiment, the influence of noise can be reduced even when the effective operating voltage of static electricity is relatively high.

[0088] The wiring board 240 has a flow path opening 247_2 that penetrates along the thickness direction and is arranged between the ground wiring GND1 for grounding and the normal ground wiring GND2, which is one of the 12 or more signal wirings SL and the normal ground wiring GND2 that is adjacent to the ground wiring GND1 for grounding and is arranged on the Z1-direction surface of the fourth insulator layer 245d, when viewed in the thickness direction. According to the first embodiment, the presence of the flow path opening 247_2 makes it possible to prevent the signal wiring SL and the normal ground wiring GND2 from being affected by noise due to static electricity.

[0089] The liquid jet head 200 further includes a flow path member 250 having flow paths connected to the flow paths of the six head chips 220, and the wiring substrate 240 is arranged between the flow path member 250 and the plurality of head chips 220 in the direction along the Z axis, and in plan view, a connecting flow path FP_2 that connects the six head chips 220 and the flow path member 250 is arranged inside the flow path opening 247_2. According to the first embodiment, the space inside the flow path opening 247_2 can be effectively utilized. By utilizing the space inside the flow path opening 247_2, the liquid jet head 200 can be made smaller in size in the XY plane than in an embodiment in which the connection flow path FP_2 is disposed outside the flow path member 250.

[0090] The ground wiring GND1 for grounding is a ground wiring for electrically connecting to a frame ground outside the liquid jet head 200, and the normal ground wiring GND2 is a wiring for constituting a part of the signal ground.

[0091] The normal ground wiring GND2 has a wiring portion GND21 having a width D2 that is larger than the width D1 of the ground wiring GND1 for grounding.

[0092] The wiring board also includes a ground spring SP1 that electrically connects the ground wiring GND1 for grounding to the frame ground.

[0093] The liquid ejection device 100 in this embodiment includes a liquid ejection head 200 and a power supply circuit 2 that generates, from a power supply, a reference potential signal VBS1, which is a reference potential signal that flows through a normal ground wiring GND2 that forms part of the signal ground.

[0094] 2. Variations The above-described embodiments can be modified in various ways. Specific modifications that can be applied to the above-described embodiments are exemplified below. Two or more embodiments arbitrarily selected from the following examples can be combined as appropriate within the scope of not mutually contradictory.

[0095] 2-1. First modified example The first modified example differs from the first embodiment in that there is an area where the ground wiring GND1 for grounding and a plurality of signal wirings or normal ground wiring GND2 overlap in plan view. The first modified example will be described below.

[0096] FIG. 8 is a diagram illustrating a wiring board 240A according to a first modification. FIG. 8 shows a cross-sectional view of the wiring board 240A taken along line VII-VII in FIG. 6. In addition to the wiring board 240A, FIG. 8 also shows a portion of the holder 230. As shown in FIG. 8, the wiring board 240A is configured by stacking a first insulator layer 245aA, a second insulator layer 245bA, and a third insulator layer 245cA in this order along the Z axis. In the following description, the first insulator layer 245aA, the second insulator layer 245bA, and the third insulator layer 245cA may be referred to as insulator layer 245A without distinction. Thus, the number of insulator layers 245A included in the wiring board 240A is different from the number of insulator layers 245 included in the wiring board 240.

[0097] The wiring board 240A has a ground wiring GND1A for grounding instead of the ground wiring GND1 for grounding. The ground wiring GND1A for grounding has a wiring portion GND11, a through-hole wiring GND12A, and a wiring portion GND13A. The through-hole wiring GND12A is arranged along the through-hole 242bA that penetrates the wiring board 240A, specifically the three insulator layers 245A, along the Z axis. The wiring portion GND13A is arranged along the X axis on the surface of the third insulator layer 245c facing the Z2 direction. The end of the wiring portion GND13A in the X1 direction is located near the center of the width of the wiring board 240A in the direction along the X axis.

[0098] Furthermore, the wiring substrate 240A has a plurality of signal wirings SLA. Specifically, in the example shown in FIG. 8, the plurality of signal wirings SLA include signal wirings SLA_1, SLA_2, SLA_3, SLA_4, via wirings SLA_5, and SLA_6. Hereinafter, the signal wirings SLA of the wiring substrate 240A may be simply referred to as signal wirings SLA. In addition to the signal wirings SLA shown in FIG. 8, the wiring substrate 240A may have signal wirings SLA (not shown). However, in FIG. 8, to avoid complication of the drawing, the signal wirings SL located in the Y1 direction from line VII-VII when viewed in the Y1 direction are omitted. Note that some or all of the signal wirings SLA shown in FIG. 8 may be normal ground wirings GND2.

[0099] The signal wiring SLA_1 is disposed on the surface of the first insulator layer 245aA facing the Z1 direction and in the X1 direction with respect to the wiring portion GND11. The signal wiring SLA_2 and the signal wiring SLA_3 are disposed between the first insulator layer 245aA and the second insulator layer 245bA. The signal wiring SLA_2 is disposed in the X1 direction with respect to the through-hole wiring GND12A. The signal wiring SLA_3 is disposed in the X1 direction with respect to the signal wiring SLA_2. The signal wiring SLA_4 is disposed on the surface of the third insulator layer 245cA facing the Z2 direction and in the X1 direction with respect to the wiring portion GND13A. The via wiring SLA_5 is a wiring for electrically connecting the signal wiring SLA_1 and the signal wiring SLA_4 and is disposed along the through-hole 242f that penetrates the wiring substrate 240A along the Z axis. The via wiring SLA_6 is a wiring for electrically connecting the signal wiring SLA_1 and the signal wiring SLA_2, and is arranged along the through hole 242g that penetrates the first insulator layer 245aA and the second insulator layer 245aB along the Z axis. Similar to a through hole, a via is a through hole that penetrates a multilayer substrate and is provided to provide electrical connection between multiple insulator layers of the multilayer substrate or between two wirings provided on either side of the multilayer substrate. However, like the through hole 242g, a via can also penetrate only some of the multiple insulator layers of the multilayer substrate.

[0100] An area RGND shown in FIG. 8 is an area showing the vicinity of the through-hole wiring GND12A. As shown in the area RGND, the signal wiring SLA and the normal ground wiring GND2 are not arranged near the through-hole wiring GND12A included in the ground wiring GND1A for grounding. An area RSL1 shown in FIG. 8 is an area showing the vicinity of the via wiring SLA_5. As shown in the area RSL1, the ground wiring GND1A for grounding is not arranged near the signal wiring SLA or the normal ground wiring GND2.

[0101] As can be seen from FIG. 8, the region RSL2 shown in FIG. 8 is a region where the ground wiring GND1A for grounding and the signal wiring SLA_1 and signal wiring SLA_2 overlap in a plan view. When the region RSL2 is viewed in the Y1 direction, two of the three insulator layers 245A, the second insulator layer 245bA and the third insulator layer 245cA, are present between the ground wiring GND1A for grounding and the signal wiring SLA_1 and signal wiring SLA_2. The Y1 direction is an example of a "direction perpendicular to the thickness direction of the wiring substrate." Neither the multiple signal wirings SLA nor the normal ground wiring GND2 of the wiring substrate 240A are present between the two insulator layers 245A. Since none of the multiple signal wirings SLA and the normal ground wiring GND2 of the wiring board 240A are present between the two insulator layers 245A, the signal wiring SLA or the normal ground wiring GND2 can be prevented from being affected by static electricity noise, compared to an embodiment in which the signal wiring SLA or the normal ground wiring GND2 is present between these two insulator layers 245A. However, in the first modification, when the region RSL2 is viewed in the Y1 direction, two insulator layers 245A are present between the ground wiring GND1A and the signal wiring SLA_1 and the signal wiring SLA_2, but this is not limited to this. When the region RSL2 is viewed in the Y1 direction, the number of insulator layers 245A present between the ground wiring GND1A and the signal wiring SLA_1 and the signal wiring SLA_2 is preferably three rather than two, and more preferably four.

[0102] 2-2. Second modified example The second modified example differs from the first embodiment and the first modified example in that the ground spring SP2 abuts against the head cover 210 via the inside of the holder 230. The second modified example will be described below.

[0103] 9 is a diagram for explaining a head module 9B in a second modified example. The head module 9B differs from the head module 9 in that it has a liquid jet head 200B instead of the liquid jet head 200, and has a fastening screw SC1 instead of the ground spring SP1. The liquid jet head 200B differs from the liquid jet head 200 in that it has a holder 230B instead of the holder 230, and has a wiring board 240B instead of the wiring board 240.

[0104] Holder 230B differs from holder 230 in that it has through-holes 238 for inserting ground springs SP2B in the second modified example. Ground springs SP2B are disposed inside holder 230B.

[0105] The wiring board 240B differs from the wiring board 240 in that it has a screw receiving portion 249 instead of the ground spring abutment portion 248a. The screw receiving portion 249 has a screw hole, as shown in the figure, on a surface facing the Z1 direction, and a fastening screw SC1 is inserted into and screwed into this screw hole, thereby fixing the liquid jet head 200B to the base 91. The screw receiving portion 249 and the fastening screw SC1 are made of a conductive material such as metal.

[0106] 9 shows the path RTB along which static electricity travels when it is generated on the ejection surface SN. The path RTB passes through the head cover 210, the ground spring SP2B, the ground spring contact portion 248b, the ground wiring GND1, the screw receiving portion 249, and the fastening screw SC1, and reaches the base 91.

[0107] As described above, according to the second modified example, the multiple head chips 220 are fixed to the head cover 210, and the liquid ejection head 200 further includes a holder 230 that houses the multiple head chips 220 between the head cover 210 and the holder 230, and a ground spring SP2B that is a conductive member arranged inside the holder 230 and electrically connects the head cover 210 and the ground wiring GND1 for grounding of the wiring board 240. According to the second modified example, it is possible to reduce the size of the area around head cover 210 compared to an embodiment in which ground spring SP2B is provided outside head cover 210. For example, if there are gaps between multiple head chips 220 housed in holder 230B at the design stage of holder 230B, the second modified example can be applied by inserting ground spring SP2B into these gaps.

[0108] 2-3.Third Modification The third modified example differs from the first embodiment, the first modified example, and the second modified example in that the ground wiring GND1 for grounding and the normal ground wiring GND2 are electrically connected to the wiring member. The third modified example will be described below.

[0109] FIG. 10 is a diagram illustrating a wiring board 240C according to a third modification. The wiring board 240C differs from the wiring board 240 in that it has a ground wiring GND1C instead of the ground wiring GND1, a normal ground wiring GND2C instead of the normal ground wiring GND2, a connector 243_3 instead of the connectors 243_1 and 243_2, and a signal wiring SLC instead of the multiple signal wirings SL. To avoid cluttering the drawings, the wiring board 240C does not show the openings through which the wiring members 220i of the head chip 220 are inserted and the terminals electrically connected to the wiring members 220i. In FIG. 10, the insulating portions of the wiring board 240C are indicated by light shading. The wiring board 240C may be a multilayer board or a double-sided board having circuit patterns on both sides of a single board.

[0110] As shown in FIG. 10 , a wiring member 244_3 electrically connected to the relay substrate 97 is detachably connected to the connector 243_3. The wiring member 244_3 is formed of a flexible substrate, similar to the wiring members 244_1 and 244_2. The wiring member 244_3 has three signal lines SLD, a ground line GND3 for grounding, and a normal ground line GND4. The ground line GND3 is an example of a "third ground line," and the normal ground line GND4 is an example of a "fourth ground line." In FIG. 10 , the ground line GND3 and the ground line GND1C for grounding are shaded with diagonal lines from the upper left to the lower right. The normal ground line GND4 and the normal ground line GND2C are shaded with diagonal lines from the upper right to the lower left.

[0111] As shown in FIG. 10, the ground wiring GND1C has a wiring portion GND1C1 and a wiring portion GND1C2. The wiring portion GND1C1 is located at the X2-direction end of the wiring substrate 240C and extends along the Y-axis. A through-hole 242h penetrating the wiring substrate 240 is provided at the Y1-direction end of the wiring portion GND1C1, and a through-hole wiring is provided along the through-hole 242h. Although not shown, a ground spring contact portion that contacts the ground spring SP1 is provided on the surface of the wiring substrate 240C facing the Z2 direction. This ground spring contact portion is directly and electrically connected to the through-hole wiring provided along the through-hole 242h. The Y2-direction end of the wiring portion GND1C1 is directly and electrically connected to the wiring portion GND1C2.

[0112] The wiring portion GND1C2 is located at the Y2-direction end of the wiring substrate 240C and is arranged to extend along the X-axis. The X1-direction end of the wiring portion GND1C2 is electrically connected to the ground wiring GND3 for grounding via the connector 243_3.

[0113] The normal ground wiring GND2C is disposed inside the ground wiring GND1C on the wiring board 240C. Specifically, the normal ground wiring GND2C has a wiring portion GND2C1 and a wiring portion GND2C2. The wiring portion GND2C1 extends along the Y axis and is disposed between the center of gravity GC of the wiring board 240C in a plan view and the wiring portion GND1C1. The Y2-direction end of the wiring portion GND2C1 is directly connected to the wiring portion GND2C2 in a conductive state. The wiring portion GND2C2 extends along the X axis and is disposed between the center of gravity GC and the wiring portion GND1C2. In addition, a through-hole 242i penetrating the wiring board 240C is provided between the wiring portion GND2C2 and the wiring portion GND1C2. The end of the wiring portion GND2C2 is electrically connected to the normal ground wiring GND4 via a connector 243_3.

[0114] Each of the three signal lines SLC is electrically connected to one of the three signal lines SLD via a connector 243_3.

[0115] As in the first embodiment, it is preferable that the ground wiring GND1C be spaced apart from the plurality of signal wirings SLC and the normal ground wiring GND2C. Similarly, in the wiring member 244_3, it is preferable that the ground wiring GND3 be spaced apart from the plurality of signal wirings SLD and the normal ground wiring GND4. This electrically isolates the ground wiring GND3 from the plurality of signal wirings SLD and the normal ground wiring GND4. Furthermore, by providing the through-hole 242i between the wiring portion GND2C2 and the wiring portion GND1C2, the signal wiring SLC and the normal ground wiring GND2C can be prevented from being affected by noise due to static electricity, compared to an embodiment in which the through-hole 242i is not provided.

[0116] Furthermore, the width D2C of the normal ground wiring GND2 is greater than the width D1C of the ground wiring GND1C for grounding. The width of the normal ground wiring GND4 is also greater than the width of the ground wiring GND3 for grounding.

[0117] As described above, in the third modified example, the ground wiring GND1C for grounding is electrically connected to the ground wiring GND3 provided on the wiring member 244_3 electrically connected to the wiring board 240C, and the normal ground wiring GND2C is electrically connected to the normal ground wiring GND4 provided on the wiring member 244_3 and different from the ground wiring GND3 for grounding. According to the third modified example, the conductive member for electrically connecting the wiring board 240C and the frame ground, which is the ground spring SP1 in the first embodiment, is not required, and therefore the number of parts of the liquid jet head 200 can be reduced.

[0118] 2-4.Fourth Modification In the third modification, the ground wiring GND3 provided on the wiring member 244_3 is electrically connected to the frame ground, but this is not limited thereto. For example, if the width of the normal ground wiring GND4 provided on the wiring member 244_3 is sufficiently long, the ground wiring GND3 and the normal ground wiring GND4 may be connected. The ground wiring GND1C and the normal ground wiring GND2C are indirectly connected via the normal ground wiring GND4, which is a conductor with a sufficiently large volume, and therefore satisfy the condition of being electrically isolated. In the fourth modification, both the ground wiring GND1C and the normal ground wiring GND2C are part of the signal ground. A reference potential signal VBS1 is supplied from the power supply circuit 2 to the ground wiring GND1C and the normal ground wiring GND2C.

[0119] 2-5. Fifth Modification In each of the above aspects except for the fourth modified example, the ground wiring GND1 for grounding is electrically connected to the frame ground. Alternatively, the ground wiring GND1 for grounding may be part of the signal ground, and the normal ground wiring GND2 may be electrically connected to the frame ground. Alternatively, as described in the first embodiment, the ground wiring GND1 for grounding and the normal ground wiring GND2 may be electrically connected to the frame ground. Then, the reference potential signal VBS1 may be supplied from the power supply circuit 2 to the ground wiring connected to the frame ground.

[0120] 2-6. Sixth Modification In the above-described embodiments except for the third and fourth modifications, the ground wiring GND1 for grounding may be a part of the signal ground, and the normal ground wiring GND2 may be electrically connected to the frame ground. The ground wiring GND1 may be supplied with a reference potential signal VBS1 from the power supply circuit 2.

[0121] 2-7. Seventh Variation Although the head cover 210 in each of the above-described embodiments fixes the plurality of head chips 220, the head cover 210 may simply house the plurality of head chips 220 without fixing them.

[0122] 2-8. Eighth Variation In each of the above-described embodiments, a heat generating element may be used instead of the piezoelectric element 220f used in each of the above-described embodiments as an energy generating element that generates energy in the pressure chamber CV to eject ink.

[0123] 2-9. 9th Variation In the above-described embodiments, the frame ground outside the liquid jet head 200 is the base 91, but the frame ground outside the liquid jet head 200 is not limited to the base 91. For example, the frame ground outside the liquid jet head 200 may be the housing of the liquid jet device 100. The static electricity that reaches the base 91 reaches the housing of the liquid jet device 100, which is the frame ground, via the screw member 955, the base cover 95, and a conductive spring (not shown) that connects the base cover 95 and the housing of the liquid jet device 100.

[0124] 2-10. 10th Variation In each of the above-mentioned embodiments, a serial-type liquid ejection device that moves a carriage 71 equipped with a head module 9 back and forth has been exemplified, but the present disclosure can also be applied to a line-type liquid ejection device in which multiple nozzles N are distributed across the entire width of the medium PP.

[0125] 2-11.Other variations The above-described liquid ejection apparatus can be employed in various devices, such as facsimile machines and copiers, in addition to devices dedicated to printing. However, the use of the liquid ejection apparatus of the present disclosure is not limited to printing. For example, a liquid ejection apparatus that ejects a solution of a color material is used as a manufacturing apparatus for forming color filters for liquid crystal display devices. Furthermore, a liquid ejection apparatus that ejects a solution of a conductive material is used as a manufacturing apparatus for forming wiring and electrodes on a wiring board.

[0126] 3. Notes From the above-described exemplary embodiments, the following configurations can be understood, for example.

[0127] A liquid ejection head according to a preferred embodiment, aspect 1, includes a liquid ejection unit having a plurality of nozzles for ejecting liquid and a plurality of drive elements for ejecting liquid from the plurality of nozzles, a conductive head cover for exposing the plurality of nozzles to the outside, and a wiring board on which an integrated circuit is mounted, wherein the wiring board has a first ground wiring that is not electrically connected to the electrodes of the drive elements but is electrically connected to the head cover, and a second ground wiring that is electrically connected to the integrated circuit, and the first ground wiring and the second ground wiring are electrically isolated from each other within the wiring board. According to the first aspect, even if static electricity generated in the head cover flows into the first ground wiring, the static electricity does not reach the second ground wiring that is electrically isolated from the second ground wiring, thereby preventing the integrated circuit from failing.

[0128] In aspect 2, which is a specific example of aspect 1, the wiring board has a plurality of signal wirings, and when viewed in the thickness direction of the wiring board, the first ground wiring, the plurality of signal wirings, and the second ground wiring do not overlap each other. According to the second aspect, compared to the aspect in which the ground wiring GND1 for grounding, the plurality of signal wirings SL and the normal ground wiring GND2 overlap, it is possible to suppress static electricity from flowing into the normal ground wiring GND2.

[0129] In aspect 3, which is a specific example of aspect 2, the shortest distance in the thickness direction between the first ground wiring and any of the plurality of signal wirings and the second ground wiring that is adjacent to the first ground wiring is 4 mm or more.

[0130] In aspect 4, which is a specific example of aspect 2, the wiring board has a through hole that penetrates along the thickness direction and is arranged between the first ground wiring and one of the multiple signal wirings and the second ground wiring that is adjacent to the first ground wiring, as viewed in the thickness direction. According to the fourth aspect, the through holes can prevent the signal wirings and the second ground wiring from being affected by noise due to static electricity.

[0131] In aspect 5, which is a specific example of aspect 4, the wiring board further includes a flow path member having a flow path connected to the flow path of the liquid injection unit, the wiring board is arranged between the flow path member and the liquid injection unit in the thickness direction, and a connecting flow path connecting the liquid injection unit and the flow path member is arranged inside the through hole as viewed in the thickness direction. According to the fifth aspect, the space inside the through-hole can be effectively utilized.

[0132] In aspect 6, which is a specific example of aspect 1, the wiring board is a multilayer board having a plurality of signal wirings and three or more insulator layers stacked in a thickness direction of the wiring board, and when viewed in the thickness direction, there is a region where the first ground wiring overlaps with the plurality of signal wirings or the second ground wiring, and when viewed in a direction perpendicular to the thickness direction, two or more insulator layers of the three or more insulator layers are present between the first ground wiring and the plurality of signal wirings or the second ground wiring, and neither the plurality of signal wirings nor the second ground wiring are present between two adjacent insulator layers of the two or more insulator layers. According to the sixth aspect, the signal wiring can be prevented from being affected by noise due to static electricity, compared to an aspect in which the signal wiring is located between two adjacent insulator layers among two or more insulator layers.

[0133] In aspect 7, which is a specific example of aspect 1, the liquid ejection unit is composed of a plurality of head chips, the plurality of head chips are fixed to the head cover, and the liquid ejection head further includes a holder that accommodates the plurality of head chips between the head cover and the holder, and a conductive member that electrically connects the head cover and the first ground wiring of the wiring board. According to the seventh aspect, the area around the head cover can be made smaller than in the case where a conductive member is provided on the outside of the head cover.

[0134] In aspect 8, which is a specific example of aspect 1, the first ground wiring is electrically connected to a third ground wiring provided in a wiring member electrically connected to the wiring board, and the second ground wiring is electrically connected to a fourth ground wiring provided in the wiring member and different from the third ground wiring. According to the eighth aspect, since there is no need to provide a conductive member for electrically connecting the wiring board and the frame ground, the number of parts of the liquid jet head can be reduced.

[0135] In aspect 9, which is a specific example of aspect 1, the first ground wiring is a ground wiring for electrically connecting to a frame ground outside the liquid jet head, and the second ground wiring is a wiring for forming part of a signal ground.

[0136] In Aspect 10, which is a specific example of Aspect 9, the second ground wiring has a portion having a width greater than that of the first ground wiring.

[0137] In an eleventh aspect which is a specific example of the ninth aspect, a conductive member is provided which electrically connects the first ground wiring of the wiring board to the frame ground.

[0138] A liquid ejection device according to aspect 12, which is a preferred aspect, includes the liquid ejection head according to any one of aspects 1 to 8, and a frame ground electrically connected to at least one of the first ground wiring and the second ground wiring of the liquid ejection head, or a generation circuit that generates from a power supply a signal of a reference potential VBS that flows through at least one of the first ground wiring and the second ground wiring of the liquid ejection head that constitutes part of a signal ground.

[0139] A liquid ejection device according to a preferred aspect 13 includes a liquid ejection head according to any one of aspects 9 to 11, and a generation circuit that generates a reference potential signal from a power supply that flows to a frame ground electrically connected to the first ground wiring of the liquid ejection head, or to the second ground wiring of the liquid ejection head, which is wiring that forms part of a signal ground. [Explanation of symbols]

[0140] 2...power supply circuit, 3...drive signal generating circuit, 5...storage unit, 6...control unit, 6a...control cable, 7...movement mechanism, 8...transport mechanism, 9, 9B...head module, 14...liquid container, 71...carriage, 72...endless belt, 91...base, 93...distribution flow path member, 95...base cover, 97...relay board, 100...liquid ejection device, 200, 200B...liquid ejection head, 210...head cover, 211...exposure opening, 220...head chip, 220a...flow path substrate, 220b...pressure chamber substrate, 220c...nozzle plate, 220d...vibration absorber, 220e...vibration plate, 220f...piezoelectric element 220g...protective plate, 220h...case, 220i...wiring member, 221...drive circuit, 230, 230B...holder, 231...first wiring member opening, 233...connection tube, 238...through hole, 240, 240A, 240B, 240C...wiring board, 241...integrated circuit, 242a...second wiring member opening, 242b, 242bA...through hole, 242c...crimping through hole, 242d, 242f, 242g, 242h, 242i...through hole, 243_1, 243_2, 243_3...connector, 244_1, 244_2, 244_3...wiring member, 245, 245A...insulator layer, 246...terminal group, 247...flow path opening, 248a, 248b...ground spring contact portion, 249...screw receiving portion, 250...flow path member, 251...projection portion, 252...cable insertion hole, 911...supply hole, 913...wiring member opening, 951, 953...control cable opening, 955...screw member, 971...connector, CV...pressure chamber, Com...drive signal, D1...shortest distance, FN...nozzle surface, FP...connection flow path, G1, GC...center of gravity, GND1...ground wiring, GND11...wiring portion, GND12, GND12A...through-hole wiring, GND13, GND13A... Wiring section, GND1A, GND1C...ground wiring for grounding, GND1C1, GND1C2...wiring section, GND2...normal ground wiring, GND21...wiring section, GND2C...normal ground wiring, GND2C1, GND2C2...wiring section, GND3...ground ground wiring for grounding, GND4...normal ground wiring, IH...inlet, Img...print data, N...nozzle, Na...communicating flow path, PP...medium, R...reservoir, R1, R2...space, RGND, RSL1, RSL2...area, RT, RTB...path, Ra...supply flow path, SC1...fastening screw, SI...specified signal, SL,SL3...signal wiring, SL3_1...wiring section, SL3_2...through-hole wiring, SL3_3...wiring section, SLA...signal wiring, SLA_5, SLA_6...via wiring, SLC, SLD...signal wiring, SN...ejection surface, SP1, SP2, SP2B...ground spring, VBS...reference potential, VBS1...reference potential signal, VHV...power supply potential, VHV1...power supply potential signal, Zd...lower electrode, Zm...piezoelectric body, Zu...upper electrode, dCom...waveform specification signal.

Claims

1. a liquid ejection unit having a plurality of nozzles for ejecting liquid and a plurality of drive elements for ejecting liquid from the plurality of nozzles; a conductive head cover for exposing the plurality of nozzles to the outside; a wiring board on which an integrated circuit is mounted; Equipped with the wiring board has a first ground wiring that is not electrically connected to the electrode of the driving element but is electrically connected to the head cover, and a second ground wiring that is electrically connected to the integrated circuit, the first ground wiring and the second ground wiring are electrically isolated from each other within the wiring substrate; A liquid jet head characterized by:

2. the wiring board has a plurality of signal wirings, When viewed in the thickness direction of the wiring board, the first ground wiring, the plurality of signal wirings, and the second ground wiring do not overlap with each other. The liquid jet head according to claim 1 .

3. a shortest distance between the first ground wiring and any of the signal wirings and the second ground wiring that is adjacent to the first ground wiring is 4 mm or more when viewed in the thickness direction; The liquid jet head according to claim 2 .

4. the wiring substrate has a through hole penetrating along the thickness direction, the through hole being disposed between the first ground wiring and one of the plurality of signal wirings and the second ground wiring that is adjacent to the first ground wiring, as viewed in the thickness direction; The liquid jet head according to claim 2 .

5. a flow path member having a flow path connected to the flow path of the liquid ejection unit; the wiring substrate is disposed between the flow path member and the liquid ejecting unit in the thickness direction, a connecting flow path that connects the liquid ejecting unit and the flow path member is disposed inside the through hole when viewed in the thickness direction; The liquid jet head according to claim 4 .

6. the wiring board is a multilayer board having a plurality of signal wirings and three or more insulating layers stacked in a thickness direction of the wiring board; When viewed in the thickness direction, there is a region where the first ground wiring overlaps with the plurality of signal wirings or the second ground wiring, when viewing the region in a direction perpendicular to the thickness direction, two or more insulator layers among the three or more insulator layers are present between the first ground wiring and the plurality of signal wirings or the second ground wiring; neither the plurality of signal wirings nor the second ground wiring is present between two adjacent insulator layers among the two or more insulator layers; The liquid jet head according to claim 1 .

7. the liquid ejection unit is composed of a plurality of head chips, the plurality of head chips are fixed to the head cover, The liquid jet head includes: a holder that accommodates the plurality of head chips between itself and the head cover; a conductive member disposed inside the holder and electrically connecting the head cover and the first ground wiring of the wiring board, The liquid jet head according to claim 1 .

8. the first ground wiring is electrically connected to a third ground wiring provided on a wiring member electrically connected to the wiring board; the second ground wiring is electrically connected to a fourth ground wiring that is provided in the wiring member and is different from the third ground wiring; The liquid jet head according to claim 1 .

9. the first ground wiring is a ground wiring for electrically connecting to a frame ground outside the liquid jet head, The second ground wiring is a wiring for constituting a part of the signal ground. The liquid jet head according to claim 1 .

10. the second ground wiring has a portion having a width greater than that of the first ground wiring; The liquid jet head according to claim 9 .

11. a conductive member electrically connecting the first ground wiring of the wiring board to the frame ground; The liquid jet head according to claim 9 .

12. The liquid jet head according to claim 1 , a frame ground electrically connected to at least one of the first ground wiring and the second ground wiring of the liquid jet head, or a generation circuit configured to generate, from a power supply, a reference potential signal flowing in at least one of the first ground wiring and the second ground wiring of the liquid jet head, the at least one wiring constituting a part of a signal ground; A liquid ejection device comprising:

13. The liquid jet head according to any one of claims 9 to 11, a generation circuit that generates, from a power supply, a signal of a reference potential that flows in a frame ground that is electrically connected to the first ground wiring of the liquid jet head, or in the second ground wiring of the liquid jet head, the second ground wiring being a wiring that constitutes a part of a signal ground; A liquid ejection device comprising:

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