Liquid dispensing head, replacement device, and printing and recording device

Abstract

In the ink filling, recovery, flow path cleaning, and replacement process of a liquid ejection head, the aim is to prevent oxidation of the liquid ejection element while enabling efficient filling, recovery, and replacement at a high flow rate while driving the pump. [Solution] The system comprises a liquid discharge substrate having a discharge element for discharging liquid, a circulation pump that supplies liquid to the liquid discharge substrate via a supply channel and recovers liquid from the liquid discharge substrate via a recovery channel, a pump drive circuit for driving the circulation pump, a first connection terminal for connecting the ground of the pump drive circuit to the outside, a second connection terminal for connecting the ground of the liquid discharge substrate to the outside, a first ground wire connecting the ground of the pump drive circuit to the first connection terminal, and a second ground wire connecting the ground of the liquid discharge substrate to the second connection terminal, wherein the second connection terminal and the second ground wire are separated from the first connection terminal and the first ground wire.

Description

[Technical Field] 【0001】 This disclosure relates to a liquid ejection head for ejecting ink onto a recording medium for recording, a corresponding replacement device, and a printing and recording device. [Background technology] 【0002】 Conventionally, various recording methods equipped with liquid ejection cartridge units have been proposed as means of recording images on recording media such as paper. For example, printers using thermal transfer, wire dot, thermal, and inkjet methods have been put into practical use. Among these, the inkjet method has attracted attention as a recording method with low running costs and low recording noise, and is used in a wide range of fields. In the inkjet method, ink droplets are ejected from ink ejection ports formed by nozzle members on the surface of the recording element substrate by driving a recording element substrate equipped with a liquid ejection head unit. The inkjet method is an image recording method that forms an image by causing these ink droplets to land at desired positions on the paper surface. During image recording, ink is ejected by driving an ejection energy generating element positioned at a location corresponding to the ejection port, and the ink lands on the recording media to form an image. In the field of inkjet printer technology in recent years, even in liquid ejection head scanning type printing and recording devices, there is a demand for ink-circulating type printing and recording devices that can utilize special inks according to the recording media in order to output high-quality printed materials. A configuration has been proposed in which an ink supply path and an ink recovery path are provided for ink circulation, and a circulating flow is obtained by generating a differential pressure between the ink supply path and the ink recovery path. The ink circulation device described in Patent Document 1 has two storage sections that supply and recirculate ink to the inkjet head, and a pump that transports ink between the storage sections, all located within the liquid ejection head unit. This ink circulation device also has a pressure sensor and a control circuit that drives the pump according to the output of the pressure sensor, all located within the liquid ejection head unit. [Prior art documents] [Patent Documents] 【0003】 [Patent Document 1] Japanese Patent Publication No. 2018-30350 [Overview of the Initiative] [Problems that the invention aims to solve] 【0004】 Although not explicitly stated in Patent Document 1, it is common practice to share the reference potential wiring (ground wiring) of the control circuit that drives the pump and the reference potential wiring (ground wiring) of the inkjet head that ejects ink. This is because both are reference potential wiring (ground wiring) of circuits located within the same device (head). However, this configuration can sometimes lead to the following problems. When filling the flow path and ejection port with ink after the liquid ejection head is mounted on the printing and recording device, or when performing suction recovery to remove generated air bubbles, it may be necessary to flow ink at a high flow rate. Also, in the manufacturing process, after performing an ejection test with test ink to confirm that there are no abnormalities, the liquid ejection head unit may be shipped after undergoing a process of cleaning and replacing the flow path with a replacement fluid such as pure water or filling ink. In such cases, in order to efficiently clean and replace the flow path without leaving any test ink residue, it is necessary to flow a high flow rate of replacement fluid, such as two fluids. In configurations with ink circulation, such as that described in Patent Document 1, it is necessary to perform filling and replacement in a complex circulation channel structure including a sub-tank. To improve efficiency, it is desirable to perform filling, recovery, and replacement while driving the circulation pump. To drive the circulation pump, a drive signal is transmitted from the printing and recording device or manufacturing device to the pump drive circuit provided in the liquid ejection head unit. The ground (pump GND) wiring for the pump drive circuit is connected to the ground of the printing and recording device or manufacturing device. Normally, the ground (pump GND) wiring of the pump drive circuit and the ground (VSS) wiring of the liquid ejection substrate are shared (short-circuited) within the liquid ejection head unit. The ink and replacement liquid flowing into the liquid ejection element are triboelectrically charged. As a result, the liquid ejection element is repeatedly charged by the incoming ink and replacement liquid and then discharged to ground. In this way, the surface of the liquid ejection element oxidizes. When the surface of the liquid ejection element oxidizes, the thermal efficiency changes, normal ejection characteristics may not be obtained, or the ejection durability may decrease.When performing ink filling, recovery, and replacement operations in a liquid ejection head, the circulating channel structure is inefficient. Therefore, it is desirable to run a circulation pump while flowing a high flow rate of liquid, but this causes oxidation of the protective film covering the ejection energy generating element. 【0005】 This disclosure has been made in view of the above-mentioned problems, and aims to enable efficient ink filling, recovery, and replacement at a high flow rate while driving the pump, in the ink filling, recovery, flow path cleaning, and replacement process of a liquid ejection head, while preventing oxidation of the liquid ejection element. [Means for solving the problem] 【0006】 One embodiment of the present disclosure is a liquid discharge head comprising: a liquid discharge substrate having a discharge element for discharging liquid; a circulation pump for supplying liquid to the liquid discharge substrate via a supply channel and recovering liquid from the liquid discharge substrate via a recovery channel; a pump drive circuit for driving the circulation pump; a first connection terminal for connecting the ground of the pump drive circuit to the outside; a second connection terminal for connecting the ground of the liquid discharge substrate to the outside; a first ground wire connecting the ground of the pump drive circuit to the first connection terminal; and a second ground wire connecting the ground of the liquid discharge substrate to the second connection terminal, wherein the second connection terminal and the second ground wire are separated from the first connection terminal and the first ground wire. [Effects of the Invention] 【0007】 According to this disclosure, in the ink filling, recovery, flow path cleaning, and replacement process of a liquid ejection head, it is possible to perform efficient filling, recovery, and replacement at a high flow rate while driving the pump, while preventing oxidation of the liquid ejection element. [Brief explanation of the drawing] 【0008】 [Figure 1] (a) A perspective view showing the schematic configuration of the printing and recording device of this disclosure; (b) A block diagram showing the control system of the printing and recording device. [Figure 2] Exploded perspective view of the liquid discharge head of this disclosure [Figure 3] Schematic external view of the ink circulation unit of the present disclosure [Figure 4] Schematic diagram of the ink circulation path of the present disclosure [Figure 5] Schematic diagram of pump drive wiring connection [Figure 6] Schematic diagram of a liquid ejection head including a head electric substrate and an inkjet recording apparatus [Figure 7] Schematic diagram of replacement process outline [Figure 8] Explanation diagram of protective film oxidation in the replacement process [Figure 9] Explanation diagram of protective film oxidation in the replacement process [Figure 10] Schematic diagram of a liquid ejection head including a head electric substrate and a replacement apparatus [Figure 11] Configuration for suppressing protective film oxidation in the replacement process (first embodiment) [Figure 12] Schematic diagram of a liquid ejection head including a head electric substrate and a replacement apparatus according to the first embodiment [Figure 13] Schematic diagram of a liquid ejection head including a head electric substrate and an inkjet recording apparatus according to the first embodiment [Figure 14] Schematic diagram of a liquid ejection head including a head electric substrate and an inkjet recording apparatus according to the second embodiment 【Mode for Carrying Out the Invention】 【0009】 Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. Note that the following embodiments do not limit the disclosure according to the claims. Although a plurality of features are described in the embodiments, all of these plurality of features are not necessarily essential for the disclosure, and the plurality of features may be arbitrarily combined. Further, in the accompanying drawings, the same or similar configurations are denoted by the same reference numerals, and redundant descriptions may be omitted. 【0010】 Note that, in this embodiment, the configuration of a serial scan type printing and recording apparatus is shown, but the present invention is also applicable to a full multi-head type liquid ejection head that has a nozzle array corresponding to the printing width and performs image recording without scanning. 【0011】 FIG. 1(a) is a schematic perspective view of a configuration example of a printing and recording apparatus using a liquid ejection head 102, and FIG. 1(b) is a block diagram of a control system of the printing and recording apparatus. The printing and recording apparatus of the present embodiment is an inkjet recording apparatus 101 of a serial scan type that ejects ink from the liquid ejection head 102 to record an image on a recording medium P. The liquid ejection head 102 is mounted on a carriage 106, and the carriage 106 moves in the main scanning direction of arrow X along a guide shaft 105. The recording medium P is conveyed in the sub-scanning direction of arrow Y that intersects (in this example, is orthogonal to) the main scanning direction by conveyance rollers 108, 109, 110, and 111. An ink circulation unit 107 is mounted on the liquid ejection head 102, and ink circulation is performed inside a discharge unit 204 (see FIG. 2(a)) described later. A discharge energy generating element 217 (FIG. 2(b)) provided in the discharge unit 204 is driven by a head driver 128 in response to an input signal from a head electric substrate 203 (see FIG. 2(a)). Electric wiring, ink, and air pipes necessary for discharge are supplied to the carriage 106 by a guide 112. 【0012】 A processor 121 such as a CPU controls the inkjet recording apparatus 101 based on a program stored in a ROM 122 and describing processing procedures and the like, and a RAM 123 is used as a work area and the like for executing those processes. The processor 121 controls the head driver 128 based on image data input from a host device 141 outside the inkjet recording apparatus 101. Further, the processor 121 controls a carriage motor 125 for moving the carriage 106 via a motor driver 124, and controls a conveyance motor 127 for conveying the recording medium P via a motor driver 126. 【0013】 The liquid ejection head 102 is capable of full-color printing using CMYK inks (cyan, magenta, yellow, and black). A cap member is positioned away from the transport path of the recording medium P. When not performing a recording operation, the liquid ejection head 102 moves relative to the cap member so that it covers the face surface of the liquid ejection head 102, preventing the ejection port from drying out and performing a suction operation to restore the fill. 【0014】 (Liquid dispensing head configuration explained) Figure 2 shows an exploded perspective view of the liquid ejection head 102 of this embodiment. As shown in Figure 2, the liquid ejection head 102 has an ink circulation unit 107. The circulation unit 107 includes circulation units 107m, 107y, 107k, and 107c, each corresponding to a different ink, and each circulation unit 107 is connected to a flow channel member 201. The connection method between the circulation unit 107 and the flow channel member 201 may be a screw-fastening method with a sealing member sandwiched in between, or other connections such as welding. The flow channel member 201 has a joint 202 for receiving ink from the main body of the inkjet recording device 101, and the joint 202 is in communication with each circulation unit 107a to d. When attaching the liquid ejection head 102 to the main body of the inkjet recording device 101, supply tubes (not shown) corresponding to each ink are connected from the main body side of the inkjet recording device 101 to each joint 202. Each ink supplied from the supply tube is supplied to each circulation unit 107a to 107d via the joint 202 of the flow channel member 201. An ejection unit 204 is connected to the bottom surface of the flow channel member 201, and the ink supplied to the circulation unit 107 is supplied to the ejection unit 204 via the flow channel member 201. The ejection unit 204 includes a liquid ejection substrate 207 equipped with an ejection energy generating element 217 for ejecting ink, a support member 205, an electrical wiring board 206 for sending electrical signals to the liquid ejection substrate 207, and a cover member 208 that covers the electrical wiring board 206. The liquid ejection substrate 207 and the electrical wiring board 206 are adhesively fixed to the support member 205. The cover member 208 is adhesively bonded to the liquid ejection substrate 207 and the electrical wiring board 206 so as to cover their surfaces. The liquid ejection substrate 207 and the electrical wiring board 206 are electrically connected to each other by wire bonding. Here, the electrical connection method may be flying lead bonding or the like. The portion of the cover member 208 corresponding to the liquid discharge substrate 207 is open. The discharge unit 204 and the flow path member 201 may be connected by an adhesive bonding method or by a screw fastening method with a sealing member sandwiched in between. 【0015】 The side of the flow channel member 201 opposite to the side where the joint 202 is located is the contact surface, and the head electrical board 203, which receives electrical signals from the main body, is connected to the contact surface. Electrical signals are sent from the head electrical board 203 to the liquid discharge board 207 via the electrical wiring board 206 of the discharge unit 204. In this case, the connection method between the head electrical board 203 and the flow channel member 201 may be a fixing method using crimping or adhesive, or a fixing method using double-sided tape. ACF crimping is used for the electrical connection between the head electrical board 203 and the electrical wiring board 206. Wire bonding or flying lead bonding may also be used for this electrical connection. 【0016】 Referring to Figure 2(b), a nozzle forming member 209 is bonded to the liquid discharge substrate 207. Multiple discharge elements 214 are formed on the nozzle forming member 209. Each discharge element 214 includes a pressure chamber 215, a discharge port 216, and a discharge energy generating element 217. The pressure chamber 215 and the discharge port 216 are in communication. The discharge ports 216 are arranged as openings on the discharge surface. Ink supplied from the first pressure control chamber 402 (see Figure 4) of the first pressure control mechanism 302 (see Figure 3) to the supply channel 212 is supplied to the multiple pressure chambers 215 formed on the liquid discharge substrate 207 of the discharge unit 204. The ink in the pressure chambers 215 is discharged from the discharge ports 216 by the energy output of the discharge energy generating element 217. Ink that is not discharged from the discharge port 216 is discharged from the pressure chamber 215 into the recovery channel 213, and then recovered into the second pressure control chamber 404 (see Figure 4) of the second pressure control mechanism 303 (see Figure 3). 【0017】 (Explanation of the circulation pathway) Figure 3 is a schematic diagram of the external appearance of an ink circulation unit 107 applied to the inkjet recording device 101 of this embodiment. One ink circulation unit 107 is provided for each color. The ink circulation unit 107 includes a first pressure control mechanism 302, a second pressure control mechanism 303, a filter 301, and a circulation pump 304. 【0018】 Figure 4 is a schematic diagram showing the circulation path for one color applied to the inkjet recording device 101 of this embodiment. Ink is supplied under pressure from the ink tank 103 to the liquid ejection head 102 by the pump 104. After debris is removed from the ink by the filter 301, it is supplied to the first valve chamber 401 of the first pressure control mechanism 302. Subsequently, the pressure of the ink is adjusted as it flows into the first pressure control chamber 402, which is connected to the first valve chamber 401 via a valve (not shown). The circulation pump 304 is a piezoelectric diaphragm pump that changes the volume inside the pump chamber by inputting a drive voltage to a piezoelectric element attached to the diaphragm, and the two check valves move alternately due to the pressure fluctuation to pump the liquid. The circulation pump 304 is driven to send ink from the pump inlet passage 408 on the downstream side to the pump outlet passage 409 on the upstream side. Driven by the circulation pump 304, the pressure-adjusted ink in the first pressure control chamber 402 is supplied to the supply passage 212 and the bypass passage 407. A portion of the supply channel 212 is formed in the channel member 201 and connected to the discharge unit 204. Similarly, a portion of the recovery channel 213 is also formed in the channel member 201 and connected to the discharge unit 204. The ink supplied to the supply channel 212 passes through the discharge element 214 formed in the liquid discharge substrate 207 of the discharge unit 204, is discharged to the recovery channel 213, and is then supplied to the pressure control chamber 404 of the second pressure control mechanism 303. As described above, the discharge element 214 includes a pressure chamber 215 and a discharge port 216. The ink supplied to the second valve chamber 403 of the second pressure control mechanism 303 is supplied to the second pressure control chamber 404, which is connected to the second valve chamber 403 via a valve (not shown). The ink supplied to the second pressure control chamber 404 is supplied to the pump inlet channel 408, passes through the circulation pump 304, is supplied to the pump outlet channel 409, and is then supplied to the first pressure control chamber 402. By configuring the ink to circulate through the discharge energy generating element 217 located on the liquid discharge substrate 207 via the circulation pump 304, it becomes possible to suppress the thickening of the discharged ink.The circulation path is not limited to a configuration that passes through the ejection energy generating element 217; it is sufficient if the ink in the ejection unit 204 is circulated within a range that effectively suppresses ink viscosity increase in the ejection element 214. 【0019】 (Explanation of the circulation pump drive mechanism) Figure 5 is a schematic diagram of the mechanism that drives the circulation pump 304. A drive signal is sent from the processor 121 mounted on the main board 501 inside the inkjet recording device 101 to the carriage board 502 via a flexible flat cable (FFC). Furthermore, from the carriage board 502 to the head electrical board 203 (see Figure 2), a signal to drive the liquid ejection board 207 (see Figure 2), along with a signal to control the pump drive circuit 601 (see Figure 6) and a reference voltage are sent via an electrical connection part 504 with contact connections. Here, the pump drive circuit 601 (see Figure 6) is mounted on the head electrical board 203. The pump drive signal output from the pump drive circuit 601 is output to the circulation pump 304 via harness wiring 505. The circulation pump 304 is driven by the pump drive signal, thereby circulating liquids such as ink. Note that the electrical connection part 504 includes connection terminals which are pins on the carriage side and connection terminals which are pads on the head electrical board 203 side. 【0020】 (Description of the head electrical circuit board and pump drive circuit) Figure 6 shows an overview of the configuration of the head electrical board 203 and a schematic diagram of the pump drive circuit 601 provided inside the head electrical board 203. The pump drive circuit 601 has functional units: a control unit 602, a boost unit 603, and an amplifier circuit 604. When the control unit 602 receives the pump drive reference voltage 611 and the control signal 612 from the inkjet recording device 101, it controls the boost unit 603. As a result, the boost unit 603 generates the pump drive voltage necessary to obtain a circulating liquid flow. The control unit 602 also controls the amplifier circuit 604. As a result, the amplifier circuit 604 amplifies the original waveform of the pump drive to the voltage output by the boost unit 603 to generate a high-voltage pump drive signal. 【0021】 In this embodiment, the head electrical board 203 is equipped with a memory 605 that records information and history specific to the liquid ejection head 102. The pump drive circuit 601 and the memory 605 are bus-connected within the head electrical board 203 and are controlled together by an I2C signal, which is a control signal 612 transmitted from the inkjet recording device 101. 【0022】 Meanwhile, the liquid ejection head 102 receives a liquid ejection substrate drive signal 613 from the inkjet recording device 101 to drive the liquid ejection substrate 207. The liquid ejection substrate drive signal 613 is transmitted to the liquid ejection substrate 207 via the head electrical board 203 and the electrical wiring board 206. For this purpose, the inkjet recording device 101 is provided with internal drive signal wiring 621, and the head electrical board 203 is provided with internal drive signal wiring 622. The liquid ejection substrate drive signal 613 drives the ejection energy generating element 217 on the liquid ejection substrate 207, thereby performing liquid ejection. 【0023】 Here, we will explain the grounds for the various signals transmitted to the liquid ejection head 102. As mentioned above, the head electrical board 203 is equipped with a pump drive circuit 601 and a memory 605. In addition, the liquid ejection board drive signal 613 passes through the head electrical board 203. In such a configuration, it is common for the grounds for the pump drive circuit 601, the memory 605, and the liquid ejection board drive signal 613 to be shared. This is because sharing allows for the provision of a more robust ground and reduces the number of signals. Reducing the number of signals allows for miniaturization and cost reduction of the liquid ejection head 102 and the inkjet recording device 101. Therefore, in the configuration shown in Figure 6, the grounds for each circuit included in the pump drive circuit 601, the ground for the memory 605, and the ground corresponding to the liquid ejection board drive signal 613 are bundled together within the head electrical board 203 by the head internal ground wiring 624. The head's internal ground wiring 624 is then grounded to the inkjet recording device 101's earth via the liquid ejection substrate ground wire 614 (recording device internal ground wiring 623), which is common to these grounds. 【0024】 (Explanation of challenges in protective film oxidation) However, the above configuration, where the ground wire is shared, can sometimes lead to problems. We will now explain some examples of this. 【0025】 When the liquid ejection head 102 is mounted on the inkjet recording device 101 and ink is filled into the flow path and ejection port, or when suction recovery is performed to remove generated air bubbles, it may be necessary to flow ink at a high flow rate through the liquid ejection head 102. In addition, in the manufacturing process, after performing an ejection test with test ink to confirm that there are no abnormalities, the liquid ejection head 102 may undergo a cleaning and replacement process with a replacement fluid such as pure water or filling ink before being shipped. In this case, in order to efficiently clean and replace the flow path without leaving any test ink residue, it is necessary to flow a high flow rate of replacement fluid, such as a two-fluid system. 【0026】 In configurations with ink circulation, such as that described in Patent Document 1, it is necessary to perform filling and replacement in a complex circulation channel structure including a sub-tank. To improve efficiency, it is desirable to perform filling, recovery, and replacement while driving the circulation pump. 【0027】 Figure 7 shows a schematic diagram of the configuration for implementing the ink replacement process in one example of a manufacturing process. 【0028】 The liquid ejection head 102 is supplied with a high-flow replacement fluid 802, a mixture of pure water and air, from a replacement device 1001 (see Figure 10) connected to the inkjet recording device 101, via a joint 202. The ink for shipment inspection and the replacement fluid 802 are then drawn in from the ejection port 216 side of the liquid ejection substrate 207 and discharged from the ejection port 216. However, in a configuration with a circulation channel as in this embodiment, the replacement of ink with replacement fluid 802 is particularly difficult and inefficient in the recovery channel. To solve this, the replacement device 1001 is electrically connected to the head electrical board 203. The replacement device 1001 then supplies a pump drive reference voltage 611 and a control signal 612 to the head electrical board 203. The ground of the liquid ejection substrate 207 is grounded to the earth of the replacement device 1001 via the liquid ejection substrate ground line 614 (common ground line). The circulation pump 304 is then driven to circulate the ink while performing the replacement operation. By doing so, it is possible to efficiently replace the fluid within the flow path while maintaining a circulating flow, including the recovery channel. 【0029】 Here, similar to the configuration described above, the grounds of each circuit included in the pump drive circuit 601, the ground of the memory 605, and the ground corresponding to the liquid discharge substrate drive signal 613 are bundled together within the head electrical board 203. These grounds are then grounded to the earth of the replacement device 1001 by a common liquid discharge substrate ground 614 line (head internal ground wiring 624) and replacement device internal ground wiring 1002. 【0030】 However, when performing the replacement while driving the circulation pump 304, problems as described below may occur. 【0031】 The schematic diagram of the problem is shown in FIG. 8. 【0032】 In the replacement process, when a replacement liquid 802 such as pure water flows in at a high flow rate, charging due to friction occurs on the wall surface of the flow path 801. Here, the wall surface of the flow path 801 is, for example, the wall surface of the flow path provided in the flow path member 201 as shown in FIG. 8. Further, the flow path 801 includes a supply flow path 212 and a recovery flow path 213. 【0033】 (a) Frictional charging (ionization) 2H2O + 2e - → 2OH - + H2 As shown in FIG. 8, the charge e - and H + ions, OH - ions move to the inside of the liquid discharge substrate 207 located downstream of the flow path 801 and reach the discharge energy generating element 217. The discharge energy generating element 217 is covered with a protective film 610 formed of Ta or the like on the surface in the discharge direction. When the replacement liquid 802 ionized by (a) reaches the protective film 610, the charge e - and OH - ions may be taken in and the surface of the protective film 610 may be oxidized. That is, Ta2O5 may occur on the surface of the protective film 610. 【0034】 (b) Surface oxidation 4Ta + 10OH - → 2Ta2O5+ 5H2+ 5e - FIG. 9 shows a diagram when the replacement is performed in a state where the protective film 610 is grounded to the ground. The protective film 610 is in structural and electrical contact with the liquid discharge substrate 207. That is, the protective film 610 is electrically short-circuited to the liquid discharge substrate 207. Therefore, when the liquid discharge substrate 207 is grounded to the ground, the protective film 610 is also grounded to the ground via the liquid discharge substrate 207. The charge e from the replacement liquid 802 ionized by frictional charging- The protective film 610 that received the signal is OH if it is grounded. - Ions are incorporated, oxidizing the surface of the protective film 610 and releasing the charge to the ground. Then, when newly ionized displacement liquid 802 is supplied, the same phenomenon is repeated. This repeated charging and discharge of static charge accelerates the oxidation of the protective film 610 surface, which is likely to have a more significant impact on discharge performance and durability. 【0035】 Figure 10 shows the electrical configuration when the protective film 610 is grounded during the replacement process. 【0036】 As mentioned above, it is common practice to have a configuration where grounds are shared as much as possible. Therefore, the grounds corresponding to the pump drive circuit 601, memory 605, and liquid discharge substrate drive signal 613 are bundled together in the head electrical board 203 by the head internal ground wiring 624. The liquid discharge substrate ground 614, connected to the head internal ground wiring 624, is then grounded to the earth of the replacement device 1001 by the wiring of the liquid discharge substrate ground 614 (replacement device internal ground wiring 1002). The pump drive voltage 611 and control signal 612 are then transmitted by the replacement device 1001 to drive the circulation pump 304. Here, the protective film 610 in the liquid discharge substrate 207 is also bundled together in the head electrical board 203 by the head internal ground wiring 624. And, as described above, the liquid discharge substrate ground 614, connected to the head internal ground wiring 624, is then grounded to the earth of the replacement device 1001 by the wiring of the liquid discharge substrate ground 614 (replacement device internal ground wiring 1002). This configuration is designed to prevent damage to the ejection energy generating element 217 due to static electricity during the manufacturing process and the process of mounting the liquid ejection head onto the inkjet recording device 101. 【0037】 Under this configuration, when replacement is performed while driving the circulation pump 304, as shown in Figure 10, the charge generated by the triboelectric charging of the replacement liquid 802 in the flow path is charged onto the protective film 610. This charge is then discharged via the liquid ejection substrate ground 614, which is grounded by the replacement device 1001. This charging and discharge operation is repeated. As a result, severe oxidation occurs on the surface of the protective film 610, raising concerns that it may affect ink ejection performance and ejection durability. 【0038】 As described above, the challenges of oxidation of the protective film 610 in the ink replacement process have been explained. However, similar challenges may arise when a high flow rate of ink is used for efficiency during ink filling or ink refilling operations in the inkjet recording device 101. 【0039】 The following details the configuration that is a key feature of this disclosure. 【0040】 (First embodiment) Figure 11 shows the configuration of this embodiment where the protective film 610 is not grounded and is open. 【0041】 Charge e generated by triboelectric charging - and H + Ions, OH - The ions move into the liquid discharge substrate 207 located downstream of the flow path 801 and reach the discharge energy generating element 217, just as in the example shown in Figure 8. However, when the protective film 610 is open, the charged charge is not discharged, so the protective film 610 does not become charged beyond its capacity, and the OH supplied later is affected by the charge that has been charged to a certain extent. - This creates an ion-repulsive effect, which in turn suppresses surface oxidation of the protective film 610. 【0042】 Figure 12 shows an electrical configuration diagram when the protective film 610 is open, using the ink replacement process as a representative example. 【0043】 In the configuration of this embodiment, the ground wiring is modified as follows in order to keep the protective film 610 in a floating state while driving the circulation pump 304 during the ink replacement process. Specifically, in the configuration of this embodiment, the in-head pump ground wiring (also called the "first ground wiring") 1204 and the in-head substrate ground wiring (also called the "second ground wiring") 1205 are provided separately. The ground of the pump drive circuit 601 and the ground of the memory 605 are connected to the in-head pump ground wiring 1204, and the protective film 610 is connected to the in-head substrate ground wiring 1205. When the liquid discharge head 102 is connected to the replacement device 1001, the in-head pump ground wiring 1204 is connected to the replacement device pump ground wiring 1203 provided in the replacement device 1001, and the in-head substrate ground wiring 1205 is left open. As a result, the pump drive circuit 601 and memory 605 are grounded to the earth of the replacement device 1001 via the in-head pump ground wiring 1204 and the in-replacement device pump ground wiring 1203. Meanwhile, the protective film 610 is in a floating state. The replacement device 1001 then supplies the pump drive reference voltage 611 and the control signal 612 to the pump drive circuit 601. 【0044】 With this configuration, the pump drive circuit ground 1201 is grounded via the replacement device 1001 to drive the circulation pump 304, while the protective film 610 remains open during the replacement process. Therefore, this configuration makes it possible to suppress oxidation of the protective film 610 during the replacement process. 【0045】 Within the head electrical board 203, the head internal board ground wiring 1205, which corresponds to the ground 1202 of the liquid discharge board 207, and the head internal pump ground wiring 1204, which corresponds to the ground 1201 of the pump drive circuit 601, are in an independent relationship. To obtain insulation between the two types of grounds within the board, it is desirable to set the capacitance between the ground 1202 of the liquid discharge board 207 and the ground 1201 of the pump drive circuit 601 to 300pF or less. In other words, it is desirable to set the capacitance between the head internal board ground wiring 1205 and the head internal pump ground wiring 1204 to 300pF or less. Accordingly, it is also desirable to set the distance between the head internal board ground wiring 1205 and the head internal pump ground wiring 1204 to 0.1 mm or more. 【0046】 The configuration of this embodiment is not limited to a thermal-type discharge energy generating element 217 that discharges liquid by generating heat, but is also applicable to a piezo-type discharge energy generating element 217 that discharges liquid by the displacement of a piezoelectric element, and in either case, the above-mentioned problems are solved. 【0047】 Furthermore, in this embodiment, a configuration is shown in which a pump drive circuit 601 and a memory 605 are mounted within the head electrical board 203 of the liquid ejection head 102, but the mounted electronic circuits and electronic components are not limited to these. The key point is that the ground 1202 of the liquid ejection board 207 and the ground 1201 of the pump drive circuit 601 are not short-circuited. In other words, the in-head pump ground wiring 1204 and the in-head board ground wiring 1205 are not short-circuited. If other electronic components or electronic circuits are mounted, a separate ground may be provided, but in order to make the inkjet recording device 101 smaller, it is preferable to make the other electronic components common to one of the two types of grounds if they are mounted. However, it is not always necessary to make them common. In other words, the grounds of other electronic components may be separated from the two types of grounds described above. To put it another way, one or more third ground wirings different from the wiring for the two types of grounds described above may be provided, and the grounds of each of the other electronic components may be connected to one or more of these third ground wirings. 【0048】 Figure 13 shows a configuration diagram of the liquid ejection head 102 of this embodiment when mounted on an inkjet recording device 101. Under the operating conditions after mounting on the inkjet recording device 101, high-flow liquid is not supplied during the replacement process, so the possibility of oxidation of the protective film 610 due to triboelectric charging in the flow path is low. Therefore, in this embodiment, priority is given to the effect of reducing the number of signals within the inkjet recording device 101. Accordingly, in this embodiment, the inkjet recording device 101 is provided with a common recording device ground wiring 1301 that connects both the in-head pump ground wiring 1204 and the in-head substrate ground wiring 1205 to the ground of the inkjet recording device 101. 【0049】 (Second embodiment) Figure 14 shows a configuration diagram of the second embodiment when the liquid ejection head 102 is mounted on the inkjet recording device 101. In this embodiment, there is no common recording device ground wiring 1301 for grounding both the in-head pump ground wiring 1204 and the in-head substrate ground wiring 1205 to the ground of the inkjet recording device 101. Instead, in this embodiment, an in-recording device pump ground wiring 1402 is provided for grounding the in-head pump ground wiring 1204 to the ground of the inkjet recording device 101. In addition, an in-recording device substrate ground wiring 1401 and a switch SW are provided for grounding the in-head substrate ground wiring 1205 to the ground of the inkjet recording device 101 when necessary. When grounding the in-head substrate ground wiring 1205 to the ground of the inkjet recording device 101, the switch SW is set to the conductive state. To put the in-head substrate ground wiring 1205 into a floating state, the switch SW is set to the open state. 【0050】 By adopting this configuration, oxidation of the protective film 610 can be suppressed even when ink equivalent to the flow rate in the replacement process is flowed at a high flow rate during ink filling when the inkjet recording device 101 is installed. While complete isolation between the two types of grounds is desirable, the necessary effect can be achieved by having a resistance value of 1 MΩ or more. 【0051】 Here, the two types of grounds are the ground 1201 of the pump drive circuit 601 and the ground 1202 of the liquid discharge substrate 207. In the configuration of Figure 12, the two types of grounds, in terms of wiring, are the in-head pump ground wiring 1204 and the in-head substrate ground wiring 1205. 【0052】 In the configuration shown in Figure 14, the two types of grounds refer to the wiring: (1) the combined wiring of the in-head pump ground wiring 1204 and the in-recorder pump ground wiring 1402, and (2) the combined wiring of the in-head circuit board ground wiring 1205 and the in-recorder pump ground wiring 1401. In other words, the resistance between the two types of grounds is the combined resistance (parallel resistance) of the resistance between the in-head pump ground wiring 1204 and the in-head circuit board ground wiring 1205 and the resistance between the in-recorder pump ground wiring 1402 and the in-recorder circuit board ground wiring 1401. In this case, for example, the resistance between the in-head pump ground wiring 1204 and the in-head circuit board ground wiring 1205 must be 2 MΩ or more, and the resistance between the in-recorder pump ground wiring 1402 and the in-recorder circuit board ground wiring 1401 must also be 2 MΩ or more. However, the conditions may be relaxed, for example, by setting the resistance between the in-head pump ground wiring 1204 and the in-head circuit board ground wiring 1205 to 1 MΩ or more, and the resistance between the in-recording device pump ground wiring 1402 and the in-recording device circuit board ground wiring 1401 to 1 MΩ or more. 【0053】 As described above, in the liquid discharge head 102 which incorporates the pump drive circuit 601, by independently providing the ground 1202 of the liquid discharge substrate 207 and the ground 1201 of the pump drive circuit 601, oxidation of the protective film 610 can be suppressed even when high-flow ink is passed through the flow path. This is an effective configuration for efficiently performing replacement and filling operations. 【0054】 In other words, during the liquid ejection head's flow path cleaning and replacement process, the gland (VSS) of the liquid ejection substrate is kept in a floating state. This allows the replacement liquid, which has been charged by friction in the flow path, to be supplied to the liquid ejection element. Once it reaches a saturation point, it repels the negative charge, thereby suppressing oxidation of the liquid ejection element's surface. In other words, it is possible to provide a head that can efficiently perform ink filling, recovery, cleaning, and replacement at high flow rates while suppressing oxidation (discoloration) of the liquid ejection element. 【0055】 <Technical Features of This Disclosure> This disclosure includes the following components: 【0056】 [Configuration 1] A liquid dispensing substrate having a dispensing element that dispenses liquid, A circulation pump that supplies liquid to the liquid discharge substrate via a supply channel and recovers the liquid from the liquid discharge substrate via a recovery channel, A pump drive circuit that drives the circulation pump, A first connection terminal for connecting the ground of the pump drive circuit to the outside, A second connection terminal for connecting the ground of the liquid discharge substrate to the outside, A first ground wire connecting the ground of the pump drive circuit to the first connection terminal, A second ground wire connecting the ground of the liquid discharge substrate and the second connection terminal, Equipped with, The second connection terminal and the second ground wiring are isolated from the first connection terminal and the first ground wiring. Liquid dispensing head. 【0057】 [Configuration 2] The protective film covering the discharge element is electrically short-circuited to the liquid discharge substrate. Liquid dispensing head as described in Configuration 1. 【0058】 [Configuration 3] The resistance between the second connection terminal and the second ground wire and the first connection terminal and the first ground wire is 1 MΩ or more. A liquid dispensing head as described in configuration 1 or 2. 【0059】 [Structure 4] The head has an electrical circuit board on which the pump drive circuit is mounted, A signal wiring that transmits a liquid discharge substrate drive signal, which is a signal for driving the discharge element of the liquid discharge substrate, from an external source to the discharge element, A signal wiring that transmits a control signal, which is a signal for driving the pump drive circuit, from an external source to the pump drive circuit, Equipped with, A liquid dispensing head as described in any one of configurations 1 to 3. 【0060】 [Composition 5] It further comprises one or more other electronic circuits or electronic components, The ground of each of the one or more other electronic circuits is connected to either the first ground wire or the second ground wire. A liquid dispensing head as described in any one of configurations 1 to 4. 【0061】 [Composition 6] It further comprises one or more other electronic circuits or electronic components, The ground of each of the one or more other electronic circuits is connected to a ground wire that is different from both the first ground wire and the second ground wire. A liquid dispensing head as described in any one of configurations 1 to 4. 【0062】 [Composition 7] The capacitance between the first ground wire and the second ground wire is 300 pF or less. A liquid dispensing head as described in any one of configurations 1 to 6. 【0063】 [Structure 8] The distance between the first ground wire and the second ground wire is 0.1 mm or more. A liquid dispensing head as described in any one of configurations 1 to 7. 【0064】 [Composition 9] A replacement device for filling or restoring ink to a liquid ejection head described in any one of items 1 to 8 of the configuration, The pump drive circuit is provided with means for driving the circulation pump while keeping the second connection terminal open and grounding the first connection terminal. Replacement device. 【0065】 [Configuration 10] A printing and recording device that performs printing and recording using a liquid ejection head described in any one of configurations 1 to 8, and that fills or restores ink to the liquid ejection head, The pump drive circuit is provided with means for driving the circulation pump while keeping the second connection terminal open and grounding the first connection terminal. Printing and recording device. 【0066】 [Composition 11] The liquid discharge head has a head electrical circuit board on which the pump drive circuit is mounted, A liquid discharge substrate drive signal, which is a signal for driving the discharge element of the liquid discharge substrate, A control signal which is a signal for driving the pump drive circuit, This is transmitted from the printing and recording device to the head electrical circuit board. A printing and recording device as described in configuration 10. 【0067】 [Composition 12] A printing and recording device that performs printing and recording using a liquid ejection head described in any one of items 1 to 8 of the configuration, The device includes means for grounding the first connection terminal and the second connection terminal in common. Printing and recording device. 【0068】 [Composition 13] A printing and recording device that performs printing and recording using a liquid ejection head described in any one of items 1 to 8 of the configuration, A first grounding means for grounding the first connection terminal, A second grounding means for grounding the second connection terminal via a switch, Equipped with, When the switch is in a conductive state, the second connection terminal is grounded. When the switch is in the open state, the second connection terminal is also in the open state. Printing and recording device. 【0069】 [Composition 14] The resistance between the first grounding means and the second grounding means is 1 MΩ or more. The printing and recording device described in configuration 13.

Claims

[Claim 1] A liquid dispensing substrate having a dispensing element that dispenses liquid, A circulation pump that supplies liquid to the liquid discharge substrate via a supply channel and recovers the liquid from the liquid discharge substrate via a recovery channel, A pump drive circuit that drives the circulation pump, A first connection terminal for connecting the ground of the pump drive circuit to the outside, A second connection terminal for connecting the ground of the liquid discharge substrate to the outside, A first ground wire connecting the ground of the pump drive circuit to the first connection terminal, A second ground wire connecting the ground of the liquid discharge substrate and the second connection terminal, Equipped with, The second connection terminal and the second ground wiring are isolated from the first connection terminal and the first ground wiring. Liquid dispensing head. [Claim 2] The protective film covering the discharge element is electrically short-circuited to the liquid discharge substrate. The liquid dispensing head according to claim 1. [Claim 3] The resistance between the second connection terminal and the second ground wire and the first connection terminal and the first ground wire is 1 MΩ or more. The liquid dispensing head according to claim 1. [Claim 4] The head has an electrical circuit board on which the pump drive circuit is mounted, A signal wiring that transmits a liquid discharge substrate drive signal, which is a signal for driving the discharge element of the liquid discharge substrate, from an external source to the discharge element, A signal wiring that transmits a control signal, which is a signal for driving the pump drive circuit, from an external source to the pump drive circuit, Equipped with, The liquid dispensing head according to claim 1. [Claim 5] It further comprises one or more other electronic circuits or electronic components, The ground of one or more of the aforementioned other electronic circuits or each of the electronic circuits is connected to either the first ground wire or the second ground wire. The liquid dispensing head according to claim 1. [Claim 6] It further comprises one or more other electronic circuits or electronic components, The ground of each of the one or more other electronic circuits is connected to a ground wire that is different from both the first ground wire and the second ground wire. The liquid dispensing head according to claim 1. [Claim 7] The capacitance between the first ground wire and the second ground wire is 300 pF or less. The liquid dispensing head according to claim 1. [Claim 8] The distance between the first ground wire and the second ground wire is 0.1 mm or more. The liquid dispensing head according to claim 1. [Claim 9] A replacement device for filling or restoring ink to a liquid dispensing head according to any one of claims 1 to 8, The pump drive circuit is provided with means for driving the circulation pump while keeping the second connection terminal open and grounding the first connection terminal. Replacement device. [Claim 10] A printing and recording apparatus that performs printing and recording using a liquid ejection head according to any one of claims 1 to 8, and that fills or restores ink to the liquid ejection head, The pump drive circuit is provided with means for driving the circulation pump while keeping the second connection terminal open and grounding the first connection terminal. Printing and recording device. [Claim 11] The liquid discharge head has a head electrical circuit board on which the pump drive circuit is mounted, A liquid discharge substrate drive signal, which is a signal for driving the discharge element of the liquid discharge substrate, A control signal which is a signal for driving the pump drive circuit, This is transmitted from the printing and recording device to the head electrical circuit board. The printing and recording device according to claim 10. [Claim 12] A printing and recording apparatus that performs printing and recording using a liquid ejection head according to any one of claims 1 to 8, The device includes means for grounding the first connection terminal and the second connection terminal in common. Printing and recording device. [Claim 13] A printing and recording apparatus that performs printing and recording using a liquid ejection head according to any one of claims 1 to 8, A first grounding means for grounding the first connection terminal, A second grounding means for grounding the second connection terminal via a switch, Equipped with, When the switch is in a conductive state, the second connection terminal is grounded. When the switch is in the open state, the second connection terminal is also in the open state. Printing and recording device. [Claim 14] The resistance between the first grounding means and the second grounding means is 1 MΩ or more. The printing and recording apparatus according to claim 13.

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