Liquid ejecting head, displacement device, and printing device

Abstract

A liquid ejection head, a replacement device, and a printing device are disclosed. A liquid ejection head includes a liquid ejection substrate having an ejection element configured to eject a liquid; a circulation pump configured to supply the liquid to the liquid ejection substrate through a supply channel and collect the liquid from the liquid ejection substrate through a collection channel; a pump drive circuit configured to drive the circulation pump; a first connection terminal for connecting a ground of the pump drive circuit to an outside; a second connection terminal for connecting a ground of the liquid ejection substrate to the outside; a first ground wiring connecting the ground of the pump drive circuit to the first connection terminal; and a second ground wiring connecting the ground of the liquid ejection substrate to the second connection terminal. The second connection terminal and the second ground wiring are separated from the first connection terminal and the first ground wiring.

Description

Technical Field

[0001] This disclosure relates to a liquid ejector head configured to eject ink onto a printing medium to perform printing, and a displacement device and printing apparatus compatible with the liquid ejector head. Background Technology

[0002] To date, various printing systems equipped with liquid jet cartridge units have been proposed for printing images on printing media such as paper. For example, thermal transfer, dot-matrix, thermal, and inkjet printers are currently in practical use. Among these, inkjet systems have attracted attention due to their low operating costs and low printing noise, and are used in a wide variety of fields. Inkjet systems involve driving a printing element substrate included in a liquid jet head unit to eject ink droplets from an ink jet nozzle formed by nozzle components on the surface of the printing element substrate. An inkjet system is an image printing method that forms an image by causing these ink droplets to land at desired locations on the paper surface. During image printing, ink is ejected by driving jet energy generating elements deployed at positions corresponding to the jet nozzles, and an image is formed by the ink landing on the printing medium. In the recent field of inkjet printer technology, in liquid jet head scanning printing devices, in order to output high-quality printed products, there is a need for an ink circulation printing device capable of using special inks customized for the printing medium. The following configuration has been proposed: an ink supply channel and an ink collection channel are set up for ink circulation, and the circulation flow is obtained by generating a pressure difference between the ink supply channel and the ink collection channel. Japanese Patent Publication No. 2018-30350 describes an ink circulation device with a liquid ejector head unit. This liquid ejector head unit includes two reservoirs for supplying ink to the inkjet head and circulating the ink, and a pump for conveying ink between the reservoirs. The ink circulation device also includes a pressure sensor in the liquid ejector head unit and control circuitry for driving the pump based on the output from the pressure sensor.

[0003] Although not explicitly described in Japanese Patent Publication No. 2018-30350, it is common for the reference potential wiring (grounding wiring) of the control circuit driving the pump and the reference potential wiring (grounding wiring) of the inkjet head to be shared. This is because both are reference potential wiring (grounding wiring) of the circuit located in the same device (head). However, this configuration may cause the following problems. After the liquid jet head is installed in the printing device, high ink flow rates may be required when filling the flow channels and jet nozzles with ink, or when performing suction recovery to remove any air bubbles that may have formed. Furthermore, during the manufacturing process, after performing jetting tests with test ink to confirm the absence of abnormalities, the flow channels inside the liquid jet head unit may be cleaned and purged with a displacement liquid such as pure water or filling ink before shipment. In this case, a high-flow-rate displacement liquid such as a dual-fluid liquid is required to efficiently clean and purify the flow channels, leaving no test ink residue. In configurations with ink circulation, such as the configuration described in Japanese Patent Publication No. 2018-30350, filling and purging are required to perform filling and purging on a complex circulation channel structure including a sub-tank. To improve efficiency, it is desirable to perform filling, refilling, and displacement simultaneously with driving the circulation pump. To drive the circulation pump, a drive signal is sent from the printing or manufacturing unit side to the pump drive circuit located in the liquid ejector unit. Furthermore, the grounding (pump GND) wiring for the pump drive circuit is connected to the ground of the printing or manufacturing unit. Typically, inside the liquid ejector unit, the grounding (pump GND) wiring for the pump drive circuit and the grounding (VSS) wiring for the liquid ejection substrate are shared (short-circuited). Ink and displacement fluid flowing into the liquid ejection elements become triboelectrically charged. This causes the liquid ejection elements to be repeatedly charged by the flowing ink or displacement fluid and then neutralized by discharging to ground. This causes surface oxidation problems in the liquid ejection elements. Surface oxidation of the liquid ejection elements can alter thermal efficiency, resulting in the inability to obtain normal ejection characteristics and reduced ejection durability. In the case of filling, refilling, or displacing ink in the liquid ejector head, the circulation channel structure does not provide sufficient efficiency for the high flow rate of liquid while driving the circulation pump, leading to oxidation of the protective layer covering the ejection energy generating elements. Summary of the Invention

[0004] This disclosure was made in view of the problems mentioned above, and its purpose is to achieve efficient fill recovery and displacement at high flow rates during ink filling recovery, channel cleaning and displacement processes of liquid jet heads, while driving the pump and preventing oxidation of the liquid jet elements.

[0005] In one aspect of this disclosure, a liquid jet head is provided, comprising: a liquid jet substrate having a jetting element configured to jet liquid; a circulation pump configured to supply liquid to the liquid jet substrate via a supply channel and collect liquid from the liquid jet substrate via a collection channel; a pump drive circuit configured to drive the circulation pump; a first connection terminal for connecting a ground of the pump drive circuit to an external location; a second connection terminal for connecting a ground of the liquid jet substrate to an external location; a first ground wiring for connecting the ground of the pump drive circuit to the first connection terminal; and a second ground wiring for connecting the ground of the liquid jet substrate to the second connection terminal, wherein the second connection terminal and the second ground wiring are separate from the first connection terminal and the first ground wiring.

[0006] The features of this disclosure will become clear from the following description of embodiments with reference to the accompanying drawings. The following description of embodiments is given by way of example. Attached Figure Description

[0007] Figure 1A This is a perspective view showing a schematic configuration of the printing apparatus of this disclosure;

[0008] Figure 1B This is a block diagram showing the control system of the printing device;

[0009] Figure 2A This is an exploded perspective view of the liquid injection head disclosed herein;

[0010] Figure 2B This is a cross-sectional view of the injection unit disclosed herein;

[0011] Figure 3 This is a schematic external view of the ink circulation unit disclosed herein;

[0012] Figure 4 This is a schematic diagram of the ink circulation path disclosed herein;

[0013] Figure 5 This is a schematic diagram of the pump drive wiring connection;

[0014] Figure 6 This is a schematic diagram of a liquid jet head and an inkjet printing device, including a head electrode substrate.

[0015] Figure 7 This is a schematic diagram of the displacement process;

[0016] Figure 8A and Figure 8B This is an illustrative diagram showing the oxidation of the protective layer during the replacement treatment;

[0017] Figure 9 This is an illustrative diagram showing the oxidation of the protective layer during the replacement treatment;

[0018] Figure 10 This is a schematic diagram including a liquid jet head and a displacement device, which are part of the head electrode substrate;

[0019] Figure 11 This is a diagram illustrating the configuration for suppressing oxidation of the protective layer during the replacement process (first embodiment);

[0020] Figure 12 This is a schematic diagram of a liquid jetting head and a displacement device including a head electrode substrate according to the first embodiment;

[0021] Figure 13 This is a schematic diagram of a liquid jet head and an inkjet printing apparatus including a head electrode substrate according to the first embodiment; and

[0022] Figure 14 This is a schematic diagram of a liquid jet head and an inkjet printing apparatus including a head electrode substrate according to the second embodiment. Detailed Implementation

[0023] The embodiments will now be described in detail with reference to the accompanying drawings. The embodiments described below do not limit the scope of the claims. While multiple features are described in the embodiments, not all of these features are essential to this disclosure, and multiple features can be combined in any desired manner. Furthermore, in the drawings, the same or similar components are indicated by the same reference numerals, and repeated descriptions may be omitted.

[0024] Although the configuration of a serial scanning printing apparatus is described in this embodiment, this disclosure is also applicable to fully multi-head liquid jet heads with nozzle arrays spanning the entire width that print images without scanning.

[0025] Figure 1A This is a schematic perspective view of a printing apparatus configuration example using a liquid jet head 102. Figure 1B This is a block diagram of the control system of the printing apparatus. The printing apparatus of this embodiment is a serial scanning inkjet printing apparatus 101 for printing images on a printing medium P by ejecting ink from a liquid ejector head 102. The liquid ejector head 102 is mounted on a carriage 106. The carriage 106 moves along a guide shaft 105 in the main scanning direction indicated by arrow X. The printing medium P is conveyed by transport rollers 108, 109, 110, 111 in the secondary scanning direction indicated by arrow Y, which intersects (orthogonal to) the main scanning direction in this example. The liquid ejector head 102 is equipped with an ink circulation unit 107, and the ink is ejected in an ejection unit 204 (see below) which will be described later. Figure 2A Internal loop. Responding to the input from the head electrode substrate 203 (see...) Figure 2A The input signal of the head driver 128 drives the jet energy generating element 217 disposed in the jet unit 204. Figure 2BThe guide 112 supplies the carriage 106 with the electrical wiring, ink lines and air lines required for jetting.

[0026] A processor 121, such as a CPU, controls the inkjet printing apparatus 101 based on a program stored in ROM 122 describing the processing procedures. RAM 123 is used as a work area for performing such processing. The processor 121 controls the head driver 128 based on image data input from a host device 141 external to the inkjet printing apparatus 101. The processor 121 also controls the carriage motor 125 for moving the carriage 106 via motor driver 124, and the transport motor 127 for transporting the printing medium P via motor driver 126.

[0027] The liquid ejector head 102 is capable of full-color printing using CMYK inks (cyan, magenta, yellow, and black). The cover member is positioned outside the transport path of the printing medium P. When not printing, the cover member moves relative to the liquid ejector head 102 to a position where it covers the surface of the liquid ejector head 102, and performs a suction operation to prevent the nozzle from drying out and for refill restoration.

[0028] (Description of liquid jet head configuration)

[0029] Figure 2A This is an exploded perspective view showing the liquid injection head 102 of this embodiment. Figure 2AAs shown, the liquid jet head 102 has an ink circulation unit 107. The circulation unit 107 includes circulation units 107m, 107y, 107k, and 107c, each corresponding to a specific ink. Each circulation unit 107 is connected to a channel member 201. The circulation unit 107 and the channel member 201 can be connected by screws with a sealing member sandwiched between them, or by welding. The channel member 201 has a connector 202 for receiving ink from the body of the inkjet printing device 101. The connector 202 is connected to each of the circulation units 107m, 107y, 107k, and 107c. When the liquid jet head 102 is mounted to the body of the inkjet printing device 101, a supply tube (not shown) corresponding to each ink is connected from the body side of the inkjet printing device 101 to each connector 202. Each type of ink supplied via the supply tube is supplied to each of the circulation units 107m, 107y, 107k, and 107c through the connector 202 of the channel member 201. The ejection unit 204 is connected to the bottom surface of the channel member 201, and the ink supplied to the circulation unit 107 is supplied to the ejection unit 204 through the channel member 201. The ejection unit 204 includes: a liquid ejection substrate 207 provided with an ejection energy generating element 217 for ejecting ink; a support member 205; an electrical wiring board 206 for transmitting electrical signals to the liquid ejection substrate 207; and a cover member 208 for covering 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 joined to the liquid ejection substrate 207 and the electrical wiring board 206 to cover their surfaces. The liquid ejection substrate 207 and the electrical wiring board 206 are electrically connected to each other by wiring connection. Here, the electrical connection method can be flying wire connection, etc. The cover member 208 has an opening at a position corresponding to the liquid jetting substrate 207. The jetting unit 204 and the channel member 201 can be connected by a bonding method using adhesive or by a fixing method using screws with a sealing member sandwiched between them.

[0030] The surface of the channel member 201 opposite to the surface where the connector 202 is located is a contact surface, and the head electrode substrate 203 is connected to this contact surface to receive electrical signals from the body. The electrical signals are transmitted from the head electrode substrate 203 to the liquid jet substrate 207 via the electrical wiring board 206 of the jetting unit 204. In this case, the head electrode substrate 203 and the channel member 201 can be connected by riveting or using adhesive fixing or double-sided tape. ACF pressure bonding is used for the electrical connection between the head electrode substrate 203 and the electrical wiring board 206. Wiring bonding or flying wire bonding can also be used for this electrical connection.

[0031] refer to Figure 2BThe nozzle forming member 209 is joined to the liquid jetting substrate 207. A plurality of jetting elements 214 are formed in the nozzle forming member 209. Each of the jetting elements 214 includes a pressure chamber 215, a jetting nozzle 216, and a jetting energy generating element 217. The pressure chamber 215 and the jetting nozzle 216 communicate with each other. The jetting nozzle 216 is arranged as an opening on the jetting surface. From the first pressure control mechanism 302 (see...) Figure 3 The first pressure control chamber 402 (see) Figure 4 Ink supplied to supply channel 212 is fed into multiple pressure chambers 215 formed on liquid jetting substrate 207 of jetting unit 204. Ink in pressure chambers 215 is ejected from jetting nozzles 216 by energy output from jetting energy generating element 217. Ink not ejected from jetting nozzles 216 is discharged from pressure chambers 215 into collection channel 213 and then collected in second pressure control mechanism 303 (see...). Figure 3 The second pressure control chamber 404 (see) Figure 4 )middle.

[0032] (Description of the loop path)

[0033] Figure 3 This is a schematic external view of the ink circulation unit 107 of the inkjet printing apparatus 101 applied in 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.

[0034] Figure 4This is a schematic diagram illustrating the circulation path of one color applied to the inkjet printing apparatus 101 of this embodiment. Ink is pressurized by pump 104 and supplied from ink tank 103 to liquid ejector head 102. After dust is removed from the ink by filter 301, the ink is supplied to the first valve chamber 401 of the first pressure control mechanism 302. Then, as the ink flows into the first pressure control chamber 402, its pressure is adjusted, 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 within the pump chamber by inputting a drive voltage to a piezoelectric element attached to the diaphragm, thereby causing pressure fluctuations to alternately move two check valves and deliver ink. The circulation pump 304 is driven to deliver ink from the downstream pump inlet channel 408 to the upstream pump outlet channel 409. By driving the circulation pump 304, the ink, whose pressure is adjusted in the first pressure control chamber 402, is supplied to supply channel 212 and bypass channel 407. A portion of the supply channel 212 is formed in the channel member 201 and connected to the jetting unit 204. A portion of the collection channel 213 is also formed in the channel member 201 and connected to the jetting unit 204. Ink supplied to the supply channel 212 passes through the jetting element 214 formed on the liquid jetting substrate 207 of the jetting unit 204, is discharged into the collection channel 213, and is then supplied to the pressure control chamber 404 of the second pressure control mechanism 303. As described above, the jetting element 214 includes a pressure chamber 215 and a jetting port 216. Ink supplied to the second valve chamber 403 of the second pressure control mechanism 303 is also supplied to the second pressure control chamber 404, which is connected to the second valve chamber 403 via a valve (not shown). Ink supplied to the second pressure control chamber 404 is supplied to the pump inlet channel 408, passes through the circulation pump 304, is then supplied to the pump outlet channel 409, and is then supplied to the first pressure control chamber 402. The ink circulation via the circulation pump 304 through the jet energy generating element 217 deployed on the liquid jetting substrate 207 enables the thickening of the jetted ink to be suppressed. The circulation path is not limited to the configuration through the jet energy generating element 217, but can be configured to circulate the ink within the jetting unit 204 to a degree that effectively suppresses the thickening of the ink in the jetting element 214.

[0035] (Description of the circulating pump drive mechanism)

[0036] Figure 5 This is a schematic diagram of the mechanism for driving the circulation pump 304. Drive signals are transmitted from the processor 121, mounted on the main PCB 501 inside the inkjet printing unit 101, to the carriage plate 502 via a flexible flat cable (FFC). Additionally, a mechanism for driving the liquid jet substrate 207 (see...) Figure 2A The signals and the control pump drive circuit 601 (see) Figure 6The signal and reference voltage are transmitted from the carriage plate 502 to the head electrode board 203 via the electrical connection 504 using contact connection (see...). Figure 2A Pump drive circuit 601 (see...) Figure 6 The pump drive signal, output from the pump drive circuit 601, is transmitted to the circulation pump 304 via the wiring harness 505. The circulation pump 304 is driven by the pump drive signal, thereby circulating liquids such as ink. The electrical connection portion 504 includes connection terminals as pins on the carriage side and connection terminals as pads on the head electrode substrate 203 side.

[0037] (Description of the head circuit board and pump drive circuit)

[0038] Figure 6 This is a schematic diagram showing the overall configuration of the head electrode substrate 203 and the pump drive circuit 601 disposed inside the head electrode substrate 203. The pump drive circuit 601 has functional units: a control unit 602, a boost unit 603, and an amplifier circuit 604. Upon receiving a pump drive reference voltage 611 and a control signal 612 from the inkjet printing device 101, the control unit 602 controls the boost unit 603. The boost unit 603 then generates the pump drive voltage required to obtain the circulating flow of liquid. The control unit 602 also controls the amplifier circuit 604. The amplifier circuit 604 then amplifies the original pump drive waveform to the voltage output by the boost unit 603 to generate a high-voltage pump drive signal.

[0039] In this embodiment, the head electrode substrate 203 is provided with a memory 605 that stores information and history specific to the liquid jet head 102. The pump drive circuit 601 and the memory 605 are connected via a bus within the head electrode substrate 203 and are both controlled by an I2C signal, which is a control signal 612 sent from the inkjet printing device 101.

[0040] Simultaneously, a liquid jetting substrate drive signal 613 for driving the liquid jetting substrate 207 is sent from the inkjet printing apparatus 101 to the liquid jetting head 102. The liquid jetting substrate drive signal 613 is sent to the liquid jetting substrate 207 via the head electrical board 203 and the electrical wiring board 206. For this purpose, the inkjet printing apparatus 101 is provided with drive signal wiring 621 inside the printing apparatus, and the head electrical board 203 is provided with drive signal wiring 622 inside the head. Then, the liquid jetting substrate drive signal 613 drives the jetting energy generating element 217 disposed on the liquid jetting substrate 207, thereby jetting liquid.

[0041] Here, a description of the grounding of various signals sent to the liquid jet head 102 is given. As mentioned above, the head circuit board 203 is provided with a pump drive circuit 601 and a memory 605. The liquid jet board drive signal 613 passes through the head circuit board 203. In such a configuration, it is common for the grounding of the pump drive circuit 601, the grounding of the memory 605, and the grounding corresponding to the liquid jet board drive signal 613 to be shared. This is because sharing these groundings allows for a stronger grounding and reduces the number of signals. Reducing the number of signals allows for a reduction in the size and cost of the liquid jet head 102 and the inkjet printing device 101. For this reason, in Figure 6 In the configuration shown, the grounding of the circuits included in the pump drive circuit 601, the grounding of the memory 605, and the grounding corresponding to the liquid jet substrate drive signal 613 are bundled together within the head electrical substrate 203 by the grounding wiring 624 inside the head. The grounding wiring 624 inside the head is grounded to the ground of the inkjet printing device 101 via the wiring of the liquid jet substrate grounding 614 (grounding wiring 623 inside the printing device) shared by these grounds.

[0042] (Description of the protective layer oxidation problem)

[0043] However, the above configuration with a shared grounding wiring can sometimes cause problems. Examples of such problems will be described below.

[0044] After the liquid ejector head 102 is mounted on the inkjet printing unit 101, it may be necessary to fill the channels and nozzles with ink or perform suction recovery to remove any air bubbles that may have formed, in which case the ink may flow through the liquid ejector head 102 at a high flow rate. Furthermore, during the manufacturing process, after performing jetting tests with test ink to confirm the absence of abnormalities, the channels inside the liquid ejector head 102 may be cleaned and replaced with a replacement liquid such as pure water or filling ink before shipment. In this case, to efficiently clean and replace the channels without leaving any test ink residue, a replacement liquid such as a two-fluid liquid needs to be jetted at a high flow rate.

[0045] In configurations with ink circulation, such as those described in Japanese Patent Publication No. 2018-30350, filling and displacement need to be performed on a complex circulation channel structure including a secondary tank. To improve efficiency, it is desirable to perform filling recovery and displacement simultaneously with driving the circulation pump.

[0046] Figure 7 This is a schematic diagram illustrating a configuration for performing ink replacement during the manufacturing process, showing an example of such a configuration.

[0047] From the replacement device 1001 connected to the inkjet printing unit 101 (see...) Figure 10A dual-fluid displacement liquid 802 (a mixture of pure water and air) is supplied to the liquid jet head 102 at a high flow rate via connector 202. Then, factory-checked ink and displacement liquid 802 are drawn from the jet port 216 side of the liquid jet substrate 207 and discharged from the jet port 216. In this case, as in the configuration with circulation channels in this embodiment, it is difficult to displace the ink with displacement liquid 802, especially in the channels on the collection side, resulting in poor efficiency. To solve this problem, displacement device 1001 is electrically connected to the head electrical substrate 203. Displacement device 1001 then supplies a pump drive reference voltage 611 and a control signal 612 to the head electrical substrate 203. The ground of the liquid jet substrate 207 is grounded to the ground of displacement device 1001 via wiring of liquid jet substrate ground 614 (a common ground wiring). Then, the displacement operation is performed while driving the circulation pump 304 to circulate the ink. This achieves highly efficient displacement within the channels while obtaining a circulating flow including the collection channels.

[0048] As with the configuration described above, the grounding of the various circuits included in the pump drive circuit 601, the grounding of the memory 605, and the grounding corresponding to the liquid jet substrate drive signal 613 are bundled within the head electrical substrate 203. These groundings are then grounded to the ground of the displacement device 1001 via wiring of the liquid jet substrate grounding 614 shared by these groundings (grounding wiring 624 inside the head) and grounding wiring 1002 inside the displacement device.

[0049] However, performing displacement while driving the circulating pump 304 may cause the following problems.

[0050] Figure 8A and Figure 8B This is a schematic diagram illustrating the problem.

[0051] During the displacement process, when a displacement liquid 802, such as pure water, is introduced at a high flow rate, charging occurs due to friction against the wall surface of the channel 801. Here, the wall surface of the channel 801 refers to, for example,... Figure 8A The wall surface of the channel provided in the channel member 201 is shown. The channel 801 includes a supply channel 212 and a collection channel 213.

[0052] (a) Frictional charging (ionization): 2H₂O + 2e⁻ → 2OH⁻ - +H2

[0053] like Figure 8A As shown, the charge e generated by triboelectric charging - H + Ions and OH -Ions migrate to the liquid jetting substrate 207 downstream of channel 801 and reach the jetting energy generating element 217. The surface of the jetting energy generating element 217 in the jetting direction is covered by a protective layer 610 made of Ta or the like. Figure 8A When the ionized displacement liquid 802 reaches the protective layer 610, the displacement liquid 802 may absorb charge e. - and OH - The surface of the protective layer 610 is ionized and oxidized. In other words, Ta2O5 can be generated on the surface of the protective layer 610 (see...). Figure 8B ).

[0054] (b) Surface oxidation with 4Ta + 10OH - →2Ta₂O₅ + 5H₂ + 5e -

[0055] Figure 9 The case where displacement is performed with the protective layer 610 grounded is illustrated. The protective layer 610 is in structural and electrical contact with the liquid jetting substrate 207. In other words, the protective layer 610 is electrically short-circuited with the liquid jetting substrate 207. Therefore, when the liquid jetting substrate 207 is grounded, the protective layer 610 is also grounded via the liquid jetting substrate 207. The protective layer 610 receives charge e from the displacement liquid 802, which is ionized by triboelectric charging. - When grounded to the ground, OH - Ions are absorbed, thereby oxidizing the surface of the protective layer 610 and dissipating the charge to ground. The same phenomenon is then repeated when freshly ionized displacement liquid 802 is supplied. This repeated charging and discharging of charge accelerates the surface oxidation of the protective layer 610, thereby increasing the likelihood of significantly affecting spray performance and durability.

[0056] Figure 10 This is a diagram showing the electrical configuration when the protective layer 610 is grounded during the replacement process.

[0057] As mentioned above, sharing grounding is common practice. Therefore, the groundings corresponding to the pump drive circuit 601, memory 605, and liquid jetting substrate drive signal 613 are bundled together within the head electrical substrate 203 via grounding wiring 624 inside the head. The wiring of the liquid jetting substrate grounding 614 (grounding wiring 1002 inside the displacement device), connected to the grounding wiring 624 inside the head, is grounded to the ground of the displacement device 1001. The displacement device 1001 then sends a pump drive voltage 611 and a control signal 612 to drive the circulation pump 304. The protective layer 610 within the liquid jetting substrate 207 is also bundled together within the head electrical substrate 203 via grounding wiring 624 inside the head. As described above, the wiring of the liquid jetting substrate grounding 614 (grounding wiring 1002 inside the displacement device), connected to the grounding wiring 624 inside the head, is grounded to the ground of the displacement device 1001. This configuration suppresses damage to the jetting energy generating element 217 due to electrostatic discharge during manufacturing processes and during the process of mounting the liquid jetting head onto the inkjet printing device 101.

[0058] When performing displacement while driving the circulation pump 304 with this configuration, such as Figure 10 As shown, the charge generated by the triboelectric charging of the displacement liquid 802 within the channel is charged to the protective layer 610. The charge is then discharged via the liquid jetting substrate grounding 614, which is grounded to ground through the displacement device 1001. This charging and discharging operation is repeated. This can cause severe oxidation on the surface of the protective layer 610, potentially affecting ink jetting performance and jetting durability.

[0059] The oxidation problem of the protective layer 610 during the ink replacement process has been described above. However, similar problems may also occur when high-flow-rate ink is ejected to improve efficiency during the ink filling and filling recovery operations in the inkjet printing apparatus 101.

[0060] The configuration that is a feature of this disclosure will now be described in detail.

[0061] (First Embodiment)

[0062] Figure 11 This is a diagram showing the configuration of this embodiment where the protective layer 610 is open and not grounded.

[0063] The charge e generated by triboelectric charging - H + Ions and OH - Ions move into the liquid jet substrate 207 downstream of channel 801, and as... Figure 8A and Figure 8BIn the example shown, the energy reaches the jet-generating element 217. However, with the protective layer 610 open-circuited, the accumulated charge is not discharged, and therefore the protective layer 610 is not charged beyond its capacity. Instead, a certain amount of accumulated charge repels the subsequently supplied OH-. - Ions. This effectively inhibits surface oxidation of the protective layer 610.

[0064] Figure 12 This is a diagram illustrating the electrical configuration with the protective layer 610 open, using ink replacement processing as a typical example.

[0065] In this embodiment, the grounding wiring is modified to maintain the protective layer 610 in a floating state while driving the circulating pump 304 during the ink replacement process. Specifically, in this embodiment, a pump grounding wiring (also referred to as a "first grounding wiring") 1204 and a substrate grounding wiring (also referred to as a "second grounding wiring") 1205 are respectively provided inside the head. The ground of the pump drive circuit 601 and the ground of the memory 605 are connected to the pump grounding wiring 1204 inside the head, and the protective layer 610 is connected to the substrate grounding wiring 1205 inside the head. When the liquid jet head 102 is connected to the replacement device 1001, the pump grounding wiring 1204 inside the head is connected to the pump grounding wiring 1203 inside the replacement device 1001, and the substrate grounding wiring 1205 inside the head remains open. Therefore, the pump drive circuit 601 and the memory 605 are grounded to the ground of the replacement device 1001 via the pump grounding wiring 1204 inside the head and the pump grounding wiring 1203 inside the replacement device. Meanwhile, the protective layer 610 is in a floating state. The pump drive reference voltage 611 and control signal 612 are supplied from the displacement device 1001 to the pump drive circuit 601.

[0066] With this configuration, the circulating pump 304 can be driven while the protective layer 610 is in an open-circuit state, even when the pump drive circuit ground 1201 is grounded to ground via the displacement device 1001. Therefore, this configuration can suppress oxidation of the protective layer 610 during the displacement process.

[0067] Within the head electrode substrate 203, the internal substrate grounding wiring 1205 corresponding to the grounding 1202 of the liquid jet substrate 207 and the internal pump grounding wiring 1204 corresponding to the grounding 1201 of the pump drive circuit 601 are independent of each other. To ensure insulation between the two types of grounding within the substrate, it is preferable that the capacitance between the grounding 1202 of the liquid jet substrate 207 and the grounding 1201 of the pump drive circuit 601 is set to be less than or equal to 300 pF. In other words, it is preferable that the capacitance between the internal substrate grounding wiring 1205 and the internal pump grounding wiring 1204 is set to be less than or equal to 300 pF. Therefore, it is preferable that the distance between the internal substrate grounding wiring 1205 and the internal pump grounding wiring 1204 is set to be greater than or equal to 0.1 mm.

[0068] The configuration of this embodiment is not limited to the thermal jet energy generating element 217 that jets liquid by generating heat, but is also applicable to the piezoelectric jet energy generating element 217 that jets liquid by displacing the piezoelectric element, and solves the problems mentioned above in any case.

[0069] Furthermore, although this embodiment employs a configuration where the pump drive circuit 601 and memory 605 are installed within the head electrical substrate 203 included in the liquid jet head 102, the electronic circuits and components to be installed are not limited to this. The key point is that the ground 1202 of the liquid jet substrate 207 is not short-circuited with the ground 1201 of the pump drive circuit 601. In other words, the pump ground wiring 1204 inside the head is not short-circuited with the substrate ground wiring 1205 inside the head. If other electronic components or circuits are installed, separate grounding can be provided. However, to further reduce the size of the inkjet printing apparatus 101, it is preferable that other electronic components to be installed share one of the two types of grounding. However, sharing grounding is not necessarily required. Specifically, the grounding of other electronic components can be separate from the two types of grounding mentioned above. In other words, one or more third grounding wirings different from those used for the two types of grounding mentioned above can be provided, and the grounding of other electronic components can be connected to one of these one or more third grounding wirings.

[0070] Figure 13This is a configuration diagram showing the liquid jet head 102 with the configuration of this embodiment mounted on an inkjet printing apparatus 101. Under operating conditions after mounting on the inkjet printing apparatus 101, high-flow-rate liquid supply during the displacement process is rarely performed, thereby reducing the likelihood of oxidation of the protective layer 610 due to triboelectric charging within the channels. Therefore, in this embodiment, the effect of reducing the number of signals within the inkjet printing apparatus 101 is preferred. Therefore, in this embodiment, the inkjet printing apparatus 101 is provided with a common grounding wiring inside the printing apparatus 1301 for grounding both the pump grounding wiring 1204 inside the head and the substrate grounding wiring 1205 inside the head to the ground of the inkjet printing apparatus 101.

[0071] (Second Embodiment)

[0072] Figure 14 This is a configuration diagram showing the liquid jet head 102 mounted on the inkjet printing apparatus 101 in the second embodiment. In this embodiment, there is no common grounding wire 1301 inside the printing apparatus for grounding both the pump grounding wire 1204 and the substrate grounding wire 1205 inside the head to the ground of the inkjet printing apparatus 101. Instead, in this embodiment, there is a pump grounding wire 1402 inside the printing apparatus for grounding the pump grounding wire 1204 inside the head to the ground of the inkjet printing apparatus 101. Additionally, if needed, the substrate grounding wire 1401 and the switch SW inside the printing apparatus are also configured to ground the substrate grounding wire 1205 inside the head to the ground of the inkjet printing apparatus 101. When the substrate grounding wire 1205 inside the head is grounded to the ground of the inkjet printing apparatus 101, the switch SW is set to the ON state. To set the substrate grounding wire 1205 inside the head to the floating state, the switch SW is set to the OFF state.

[0073] By employing this configuration, oxidation of the protective layer 610 can be suppressed even when a high flow rate of ink, comparable to that in a displacement process, is injected during ink filling or similar processes when the device is mounted on the inkjet printer 101. While complete isolation between these two types of grounding is desirable, the desired effect can be achieved by providing a resistance value greater than or equal to 1 MΩ.

[0074] Here, the two types of grounding refer to grounding 1201 of the pump drive circuit 601 and grounding 1202 of the liquid jetting substrate 207. Figure 12 In terms of wiring, the two types of grounding refer to the pump grounding wiring 1204 inside the head and the substrate grounding wiring 1205 inside the head.

[0075] exist Figure 14In this configuration, regarding wiring, there are two types of grounding: (1) wiring obtained through the pump grounding wiring 1204 inside the combined head and the pump grounding wiring 1402 inside the printing device, and (2) wiring obtained through the substrate grounding wiring 1205 inside the combined head and the pump grounding wiring 1401 inside the printing device. In other words, the resistance between the two types of grounding is a combined resistance (parallel resistance) of the resistance between the pump grounding wiring 1204 and the substrate grounding wiring 1205 inside the combined head and the resistance between the pump grounding wiring 1402 and the substrate grounding wiring 1401 inside the printing device. In this case, for example, it is necessary to set the resistance between the grounding wiring 1204 and the substrate grounding wiring 1205 inside the combined head to be greater than or equal to 2MΩ, and it is also necessary to set the resistance between the pump grounding wiring 1402 and the substrate grounding wiring 1401 inside the printing device to be greater than or equal to 2MΩ. However, for example, the conditions can be relaxed by setting the resistance between the pump grounding wiring 1204 inside the head and the substrate grounding wiring 1205 inside the head to be greater than or equal to 1MΩ, and setting the resistance between the pump grounding wiring 1402 inside the printing device and the substrate grounding wiring 1401 inside the printing device to be greater than or equal to 1MΩ.

[0076] As described above, in the liquid jet head 102 including the pump drive circuit 601, by independently setting the ground 1202 of the liquid jet substrate 207 and the ground 1201 of the pump drive circuit 601, oxidation of the protective layer 610 can be suppressed even when a high flow rate of ink flows through the channel. This is an efficient configuration for efficient displacement and filling operations.

[0077] In other words, during the channel cleaning and displacement process of the liquid jet head, the grounding (VSS) of the liquid jet substrate is set to a floating state. Therefore, even when triboelectrically charged displacement liquid is supplied to the liquid jet element in the channel, the displacement liquid is charged to saturation and then repels the negative charge, thereby suppressing surface oxidation of the liquid jet element. In other words, a head can be provided that can efficiently perform ink filling recovery, cleaning, and displacement at high flow rates while suppressing oxidation (discoloration) of the liquid jet element.

[0078] According to this disclosure, during ink filling recovery, channel cleaning, and displacement treatment of the liquid jet head, efficient filling recovery and displacement can be performed at high flow rates while driving the pump, and oxidation of the liquid jet elements can also be suppressed.

[0079] While this disclosure has been described with reference to embodiments, it is to be understood that this disclosure is not limited to the disclosed embodiments. The scope of the appended claims is to be given the broadest description so as to cover all such modifications as well as equivalent structures and functions.

Claims

1. A liquid injection head, comprising: A liquid jetting substrate having jetting elements configured to jet liquid; A circulation pump configured to supply liquid to the liquid jetting substrate through a supply channel and to collect liquid from the liquid jetting substrate through a collection channel; A pump drive circuit configured to drive the circulating pump; A first connection terminal is configured to connect the ground of the pump drive circuit to an external location; A second connection terminal is configured to connect the ground of the liquid jet substrate to the outside; The first grounding wiring connects the ground of the pump drive circuit to the first connection terminal; as well as The second grounding wiring connects the ground of the liquid jetting substrate to the second connection terminal, wherein... The second connection terminal and the second grounding wiring are separated from the first connection terminal and the first grounding wiring.

2. The liquid injection head according to claim 1, wherein, The protective layer covering the spraying element is electrically short-circuited with the liquid spraying substrate.

3. The liquid injection head according to claim 1, wherein, The resistance between the second connection terminal and the second grounding wire, and the resistance between the first connection terminal and the first grounding wire, are greater than or equal to 1MΩ.

4. The liquid injection head according to claim 1, further comprising: A head circuit board on which the pump drive circuit is mounted; Signal wiring configured to send a liquid jetting substrate drive signal from the outside to the jetting element, wherein the liquid jetting substrate drive signal is a signal for driving the jetting element of the liquid jetting substrate; as well as Signal wiring configured to send control signals from the outside to the pump drive circuit, the control signals being signals used to drive the pump drive circuit.

5. The liquid injection head according to claim 1, further comprising: One or more other electronic circuits or electronic components, wherein, The grounding connection of the one or more other electronic circuits or electronic components is connected to either the first grounding wiring or the second grounding wiring.

6. The liquid injection head according to claim 1, further comprising: One or more other electronic circuits or electronic components, wherein, The grounding connection of each of the one or more other electronic circuits or electronic components is different from both the first grounding wiring and the second grounding wiring.

7. The liquid injection head according to claim 1, wherein, The capacitance between the first grounding wire and the second grounding wire is less than or equal to 300pF.

8. The liquid injection head according to claim 1, wherein, The distance between the first grounding wire and the second grounding wire is greater than or equal to 0.1 mm.

9. A displacement device for performing liquid filling or liquid filling recovery of a liquid injection head. The liquid injection head includes: A liquid jetting substrate having jetting elements configured to jet liquid; A circulation pump configured to supply liquid to the liquid jetting substrate through a supply channel and to collect liquid from the liquid jetting substrate through a collection channel; A pump drive circuit configured to drive the circulating pump; The first connection terminal is used to connect the ground of the pump drive circuit to the outside; The second connection terminal is used to connect the ground of the liquid jet substrate to the outside; The first grounding wiring connects the ground of the pump drive circuit to the first connection terminal; as well as The second grounding wiring connects the ground of the liquid jetting substrate to the second connection terminal, wherein... The second connection terminal and the second grounding wiring are separate from the first connection terminal and the first grounding wiring, wherein The replacement device includes A unit configured to drive the circulating pump when the second connection terminal is set to an open circuit state and the first connection terminal is grounded.

10. A printing apparatus for performing printing using a liquid jet head and performing liquid filling or liquid filling recovery on the liquid jet head. The liquid injection head includes: A liquid jetting substrate having jetting elements configured to jet liquid; A circulation pump configured to supply liquid to the liquid jetting substrate through a supply channel and to collect liquid from the liquid jetting substrate through a collection channel; A pump drive circuit configured to drive the circulating pump; The first connection terminal is used to connect the ground of the pump drive circuit to the outside; The second connection terminal is used to connect the ground of the liquid jet substrate to the outside; The first grounding wiring connects the ground of the pump drive circuit to the first connection terminal; as well as The second grounding wiring connects the ground of the liquid jetting substrate to the second connection terminal, wherein... The second connection terminal and the second grounding wiring are separate from the first connection terminal and the first grounding wiring, wherein The printing device includes A unit configured to drive the circulating pump when the second connection terminal is set to an open circuit state and the first connection terminal is grounded.

11. The printing apparatus according to claim 10, wherein, The liquid injection head includes a head circuit board, and the pump drive circuit is mounted on the head circuit board. A liquid jetting substrate drive signal, which serves as a signal for driving the jetting element of the liquid jetting substrate, and a control signal, which serves as a signal for driving the pump drive circuit, are sent from the printing device to the head electrode substrate.

12. A printing apparatus for performing printing using a liquid jet head. The liquid injection head includes: A liquid jetting substrate having jetting elements configured to jet liquid; A circulation pump configured to supply liquid to the liquid jetting substrate through a supply channel and to collect liquid from the liquid jetting substrate through a collection channel; A pump drive circuit configured to drive the circulating pump; The first connection terminal is used to connect the ground of the pump drive circuit to the outside; The second connection terminal is used to connect the ground of the liquid jet substrate to the outside; The first grounding wiring connects the ground of the pump drive circuit to the first connection terminal; as well as The second grounding wiring connects the ground of the liquid jetting substrate to the second connection terminal, wherein... The second connection terminal and the second grounding wiring are separate from the first connection terminal and the first grounding wiring, wherein The printing device includes a unit configured to ground both the first connection terminal and the second connection terminal.

13. A printing apparatus for performing printing using a liquid jet head. The liquid injection head includes: A liquid jetting substrate having jetting elements configured to jet liquid; A circulation pump configured to supply liquid to the liquid jetting substrate through a supply channel and to collect liquid from the liquid jetting substrate through a collection channel; A pump drive circuit configured to drive the circulating pump; The first connection terminal is used to connect the ground of the pump drive circuit to the outside; The second connection terminal is used to connect the ground of the liquid jet substrate to the outside; The first grounding wiring connects the ground of the pump drive circuit to the first connection terminal; as well as The second grounding wiring connects the ground of the liquid jetting substrate to the second connection terminal, wherein... The second connection terminal and the second grounding wiring are separate from the first connection terminal and the first grounding wiring, wherein The printing device includes A first grounding unit, configured to ground the first connection terminal; A second grounding unit, configured to ground the second connection terminal via a switch, wherein... When the switch is in the ON state, the second connection terminal is grounded, and When the switch is in the open circuit state, the second connection terminal is in the open circuit state.

14. The printing apparatus according to claim 13, wherein, The resistance between the first grounding unit and the second grounding unit is greater than or equal to 1MΩ.

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