Liquid discharge head and liquid discharge device

Abstract

Further improvements in reliability are required for liquid dispensing heads. [Solution] This disclosure relates to a liquid dispensing unit. The liquid dispensing unit of this disclosure is a liquid dispensing head having a housing having a first flow path for supplying liquid to the liquid dispensing unit and a second flow path for recovering liquid from the liquid dispensing unit, a liquid circulation unit having a supply port for supplying liquid to the supply flow path, a recovery port for recovering liquid from the recovery flow path, a pump for supplying the liquid recovered from the recovery port to the supply port, and a third flow path connecting the supply port and the recovery port via the pump. The housing has a recess having a bottom surface and a side wall connected to the bottom surface, and the liquid circulation unit is disposed in the recess, characterized in that the maximum volume of liquid that can be contained in the recess when the liquid dispensing head is in use is greater than the total volume of liquid that can be contained in the third flow path of the liquid circulation unit.

Description

Technical Field

[0001] The present invention relates to a liquid ejection head capable of ink circulation and a liquid ejection device using this liquid ejection head.

Background Art

[0002] In the field of inkjet printers in recent years, an ink circulation type liquid ejection device that can handle special inks according to a recording medium for outputting high-quality printed matter has been demanded. Such a requirement is similarly demanded in a liquid ejection device of a liquid ejection head scanning type.

[0003] In the above liquid ejection device, when the liquid ejection head scans, it is desirable that the circulation of the ink be completed within the head from the viewpoint of the influence of rocking. In Patent Document 1, in order to complete the ink circulation path within the head, a configuration is disclosed in which components necessary for circulating ink such as a pump, a pressure adjustment mechanism, a substrate for driving the pump, and a sub-tank are arranged in the head.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the liquid ejection head, further reliability is required.

Means for Solving the Problems

[0006] The liquid discharge head of the present disclosure comprises a liquid discharge unit for discharging liquid, a housing having a first flow path for supplying liquid to the liquid discharge unit and a second flow path for recovering liquid from the liquid discharge unit, and a liquid circulation unit having a supply port for supplying liquid to the first flow path, a recovery port for recovering liquid from the second flow path, a pump for supplying the liquid recovered from the recovery port to the supply port, and a third flow path connecting the supply port and the recovery port via the pump, wherein the housing has a recess having a bottom surface and a side wall connected to the bottom surface, the liquid circulation unit is disposed in the recess, and the maximum volume of liquid that can be contained in the recess when the liquid discharge head is in use is greater than the total volume of liquid that can be contained in the third flow path of the liquid circulation unit. [Brief explanation of the drawing]

[0007] [Figure 1] Figure 1 shows a liquid dispensing device of the present disclosure, where (a) is a schematic configuration diagram of the liquid dispensing device of the present disclosure, and (b) is a block diagram of the control system of the liquid dispensing device of the present disclosure. [Figure 2] Figure 2 is an exploded perspective view of the liquid dispensing head of this disclosure. [Figure 3] Figure 3 is a schematic diagram of the external appearance of the liquid circulation unit of the liquid discharge head of this disclosure. [Figure 4] Figure 4 is a schematic cross-sectional view showing the circulation path of the liquid discharge head of this disclosure. [Figure 5] Figure 5 is a schematic diagram showing the ink circulation path of the liquid ejection head of this disclosure. [Figure 6] Figure 6 is a schematic diagram showing the connection of the drive wiring for the circulation pump of the liquid discharge head of this disclosure. [Figure 7] Figure 7 is a schematic diagram showing a cross-sectional view of the head electrical circuit board of the liquid discharge head of this disclosure. [Figure 8] Figure 8 is a top view of the liquid dispensing head of the present disclosure, excluding the head cover. [Figure 9]Figure 9 is a perspective view of the liquid dispensing head of this disclosure, excluding the head cover. [Figure 10] Figure 10 is a schematic cross-sectional view of XX in Figure 8. [Figure 11] Figure 11 is a schematic cross-sectional view of the XI-XI section of Figure 10, excluding the head electrical circuit board. [Figure 12] Figure 12 is a schematic cross-sectional view of the liquid discharge head of the present disclosure, showing the case in which one circulation unit is included. [Figure 13] Figure 13 is a schematic cross-sectional view of a liquid dispensing head in a second embodiment of the present disclosure. [Figure 14] Figure 14 is a schematic diagram of the XIV-XIV section of Figure 13. [Figure 15] Figure 15 is a schematic cross-sectional view of a liquid dispensing head in a third embodiment of the present disclosure. [Modes for carrying out the invention]

[0008] The liquid dispensing head and liquid dispensing apparatus using the same described herein will be described with reference to the drawings. In this specification, directions may be defined by the X, Y, and Z axes. These axes are indicated by the directional axes with arrows shown in each drawing. Where a bidirectional arrow indicates the axial direction on each axis, it indicates that the object moves in either the "+" or "-" direction of that axis.

[0009] In this specification, when specifying the direction of each axis, the direction in which the arrow is pointing is defined as the "+" direction of each axis in the X, Y, or Z directions. That is, the "+" direction of each axis is the direction in which the arrow is pointing, and the "-" direction is the opposite direction to the direction in which the arrow is pointing. When the direction of an axis is referred to without specifying the "+" or "-" direction, it is simply called the "X-axis direction," "Y-axis direction," or "Z-axis direction."

[0010] In this specification, the terms "liquid" and "ink" are used. These terms are concepts that encompass any liquid that can be used for recording. Also, "liquid" and "ink" refer to any liquid that can be used for image formation or processing of a recording medium by being applied to the recording medium. Therefore, in this specification, the terms "liquid" and "ink" are used interchangeably. Also, in this specification, the concept of recording is not particularly limited and is applicable to industrial uses and the like. For example, it can also be used for applications such as the production of biochips, the printing of electronic circuits, and the production of semiconductor substrates. (First Embodiment)

[0011] Regarding the liquid ejection head of the present disclosure according to the first embodiment, it will be described with reference to the drawings while also covering the configuration of the liquid ejection device including the liquid ejection head. Hereinafter, the outline of the liquid ejection device according to the present disclosure will be described, and then the liquid ejection head according to the present disclosure will be described. (Liquid Ejection Device)

[0012] FIG. 1 shows a liquid ejection device provided with the liquid ejection head of the present disclosure. FIG. 1(a) is a schematic perspective view showing a configuration example of a liquid ejection device using the liquid ejection head 1. FIG. 1(b) is a block diagram showing the control system of the liquid ejection device.

[0013] Referring to FIG. 1(a), the liquid ejection device 50 of the present embodiment will be described. The liquid ejection device 50 of the present embodiment is a serial scan type device (for example, an inkjet type liquid ejection device) that ejects ink from the liquid ejection head 1 to record an image on the recording medium P. The liquid ejection device 50 of the present embodiment includes a liquid ejection head 1, a guide shaft 51, a carriage 53, a liquid circulation unit 54, conveying rollers 55, 56, 57, and 58, a guide 59, an electrical wiring board (not shown), an ink tank, a pump, and the like. The electrical wiring board generates an electrical input signal for driving the ejection energy generating element. The ink tank stores ink, and the pump is for supplying ink from the ink tank.

[0014] The liquid ejection head 1 is an inkjet-type liquid ejection head and is mounted on the carriage 53. The carriage 53 moves along the guide shaft 51 in the main scanning direction of the arrow X shown in Fig. 1(a). The transport rollers 55, 56, 57, and 58 transport the recording medium P in the sub-scanning direction of the arrow Y (in the example of this embodiment, a direction perpendicular to the X direction) that intersects the main scanning direction shown by the arrow X. In the liquid ejection device of this embodiment, the electrical wiring, ink, and air pipes necessary for liquid ejection are supplied to the carriage 53 by the guide 59. A liquid circulation unit 54 is mounted on the liquid ejection head 1, and ink circulation is performed with respect to the ejection unit 300 described later. The ejection unit 300 is provided with an ejection energy generating element, and the ejection energy generating element is driven by the head driver 1A according to an electrical input signal from the electrical wiring board.

[0015] The liquid ejection head 1 can perform full-color printing with liquids such as CMYK inks (cyan, magenta, yellow, and black). In the liquid ejection device of this embodiment, a cap member is disposed at a position deviated from the conveyance path of the recording medium P. This cap member moves relatively to a position covering the face surface of the liquid ejection head 1 when the recording operation is not performed, prevents drying of the ejection openings, and performs suction operations for filling liquids such as ink or restoring the state of the liquid ejection head.

[0016] Next, the control system of the liquid ejection device will be described with reference to Fig. 1(b). The control system in this embodiment mainly includes the following components. That is, the control system includes a CPU (control unit) 400, a ROM 401 including programs such as processing procedures, and a RAM 402. Further, the control system includes a carriage motor 403 for moving the carriage 53, a first motor driver 403A for controlling the carriage motor 403, a conveyance motor 404 for conveying the recording medium P, and a second motor driver 404A for controlling the conveyance motor 404. In addition, the control system includes an ejection unit 300 and a head driver 1A for controlling the liquid ejection unit.

[0017] In this embodiment, the CPU (control unit) 400 controls the liquid dispensing device 50 based on a program such as a processing procedure stored in the ROM 401. The RAM 402 is used as a work area for executing these processes. The CPU 400 controls the head driver 1A based on image data from a host device 100 located outside the liquid dispensing device 50. The CPU 400 controls the carriage motor 403 for moving the carriage 53 via the first motor driver 403A, and controls the transport motor 404 for transporting the recording medium P via the second motor driver 404A.

[0018] (Explanation of the liquid dispensing head configuration) The liquid discharge head of this disclosure will be described with reference to Figure 2. Figure 2 shows an exploded perspective view of the liquid discharge head 1 of this embodiment. As shown in Figure 2, the liquid discharge head 1 includes a liquid circulation unit 54, a housing 110, a joint member 200, a head electrical circuit board 210, a head cover 60, a discharge unit 300, a sealing member 350, and the like.

[0019] The liquid circulation unit 54 consists of individual liquid circulation units 54a, 54b, 54c, and 54d (hereinafter also referred to as individual liquid circulation units 54a to d) corresponding to each ink. Each individual liquid circulation unit 54a to d is connected to the housing 110 and the joint member 200 described later. In Figure 2, the number of individual liquid circulation units is shown as four, but this number can be changed depending on the number of ink types installed, and the number of individual liquid circulation units is not limited. Furthermore, in this specification, each individual liquid circulation unit may be described by referring to one of the individual liquid circulation units 54a to d corresponding to one type of ink applied to the liquid discharge head of this embodiment. In such cases, in this specification, one of the individual liquid circulation units 54a to d may also be referred to as liquid circulation unit 54.

[0020] The housing 110 has a recess formed by the bottom surface and side walls, and the individual liquid circulation units 54a to d of the liquid circulation unit 54 are arranged in this recess. In the liquid discharge head of this disclosure, it is preferable that the height of the circulation unit is higher than the height of the side wall of the housing 110.

[0021] A head cover 60 is attached to the top of the housing 110. Furthermore, a joint member 200 is attached to the housing 110 for supplying liquid (e.g., ink) from the liquid ejection device body to the liquid circulation unit 54. The joint member 200 is equipped with individual joint needles 201a, 201b, 201c, and 201d (hereinafter also referred to as individual joint needles 201a to d) corresponding to each of the individual liquid circulation units 54a to d. When the liquid ejection head is attached to the liquid ejection device, supply tubes (not shown) corresponding to each ink are connected from the recording device body side to each individual joint needle 201a to d. Each ink supplied from the supply tube is supplied to each individual liquid circulation unit 54a to d via the individual joint needles 201a to d.

[0022] An ink ejection unit 300 is connected to the bottom of the housing 110. Ink supplied to the liquid circulation unit 54 is supplied to and recovered by the ejection unit 300 via the flow paths within the housing 110 (for example, the first flow path 650 and the second flow path 652 shown in Figure 6). The ejection unit 300 consists of an ejection element 310 equipped with an actuator for ejecting ink, a support member 320, an electrical wiring board 330 for sending electrical signals to the ejection element, and a cover member 340 covering the electrical wiring board. The ejection element 310 and the electrical wiring board 330 are adhesively fixed to the support member 320, and the cover member 340 is further adhesively bonded to cover the surface of the support member 320. The ejection element 310 and the electrical wiring board 330 are electrically connected by wire bonding. Note that the method of electrical connection may be flying lead bonding or the like. The cover member 340 has an opening at the location corresponding to the ejection element 310. The ejection unit 300 and the housing 110 are joined together via a sealing member 350. The connection is made by screwing the support member 320 of the discharge unit 300 to the housing 110. Alternatively, the discharge unit 300 and the housing 110 may be joined using adhesive.

[0023] The side of the housing 110 opposite to the joint member 200 is the contact surface. The head electrical circuit board 210, which receives electrical signals from the main body, is connected to the contact surface. Electrical signals are sent from the head electrical circuit board 210 to the ejection element 310 via the electrical wiring circuit board 330 of the ejection unit 300. At this time, the connection between the head electrical circuit board 210 and the housing 110 may be fixed by crimping, adhesive, or double-sided tape. The electrical connection between the head electrical circuit board 210 and the electrical wiring circuit board 330 is made by crimping using an anisotropic conducting film (ACF). This electrical connection may also be wire bonding or flying lead bonding.

[0024] Figure 3 is a schematic diagram of the external appearance of one liquid circulation unit 54 (any of the individual liquid circulation units 54a to d) corresponding to one type of liquid (e.g., ink) applied to the liquid dispensing device of this embodiment. Preferably, the liquid circulation unit 54 has a filter 23, a first pressure adjustment means 120, and a second pressure adjustment means 150 in addition to the circulation pump 500. These components are connected by flow paths as shown in Figures 4 and 5, and constitute a circulation path within the liquid dispensing head 1 for supplying and recovering ink to and from the dispensing unit 300.

[0025] Figure 4 is a schematic longitudinal cross-sectional view showing the circulation path of one type of ink (one color ink) configured within the liquid discharge head 1. To explain the circulation path more clearly, the relative positions of each component (first pressure adjustment means 120, second pressure adjustment means 150, circulation pump 500, etc.) in Figure 4 are simplified. Figure 5 is a schematic block diagram showing the circulation path shown in Figure 4 (note that the housing portion is omitted in Figure 5). As shown in Figures 4 and 5, the first pressure adjustment means 120 includes a first valve chamber 121 and a first pressure control chamber 122. The second pressure adjustment means 150 includes a second valve chamber 151 and a second pressure control chamber 152. The first pressure adjustment means 120 is configured to have a relatively higher control pressure than the second pressure adjustment means 150. In this embodiment, by using these two pressure adjustment means 120 and 150, circulation within a constant pressure range is achieved within the circulation path. Furthermore, the pressure chamber 12 is configured to allow ink to flow at a flow rate corresponding to the pressure difference between the first pressure adjustment means 120 and the second pressure adjustment means 150. The circulation path in the liquid ejection head 1 and the flow of ink within the circulation path will be described below with reference to Figures 4 and 5. In Figures 4 and 5, the liquid circulation unit 54 represents one of the liquid ejection heads of this disclosure (for example, 54a), and the housing 110 and ejection unit 300 represent the parts corresponding to this one liquid circulation unit. Also, in Figures 4 and 5, the arrows shown within the liquid ejection head 1 indicate the direction of liquid (ink) flow.

[0026] First, the connection status of each component in the liquid ejection head 1 will be explained. The liquid ejection head 1 is equipped with an ink tank 2 and an external pump 21 on its exterior. The external pump 21 delivers ink contained in the ink tank 2 (see Figure 5) to the liquid ejection head 1. The external pump 21 is connected to the liquid circulation unit 54 via a guide (including an ink supply tube) 59 (see Figure 1). A filter 23 is provided in the ink flow path (inflow flow path) located upstream of the liquid circulation unit 54. The ink supply path (inflow flow path) located downstream of the filter 23 is connected to the first valve chamber 121 of the first pressure adjustment means 120. The first valve chamber 121 communicates with the first pressure control chamber 122 via a communication port 191A that can be opened and closed by a valve 190A shown in Figure 4. The inflow flow path is the flow path through which the liquid in the ink tank 2, located outside the liquid ejection head 1, flows into the liquid ejection head 1 in order to supply it to the pressure chamber 12.

[0027] The first pressure control chamber 122 is connected to the supply channel 130, the bypass channel 160, and the pump outlet channel 180 of the circulation pump 500. The supply channel 130 is connected to the common supply channel 18 of the discharge unit 300 via a supply port (ink supply port) 410 provided in the liquid circulation unit and a first channel (first channel 650 in Figure 6) in the housing 110 (the first channel 650 is the channel that supplies liquid to the discharge unit 300). The bypass channel 160 is connected to the second valve chamber 151 provided in the second pressure adjustment means 150. The second valve chamber 151 communicates with the second pressure control chamber 152 via a communication port 191B which is opened and closed by the valve 190B shown in Figure 4. Figures 4 and 5 show an example in which one end of the bypass channel 160 is connected to the first pressure control chamber 122 of the first pressure regulating means 120, and the other end of the bypass channel 160 is connected to the second valve chamber 151 of the second pressure regulating means 150. Alternatively, one end of the bypass channel 160 may be connected to the supply channel 130, and the other end of the bypass channel may be connected to the second valve chamber 151.

[0028] The second pressure control chamber 152 is connected to the recovery channel 140. The recovery channel 140 is connected to the second channel of the housing 110 (second channel 652 in Figure 6) and the common recovery channel 19 of the discharge unit 300 via a recovery port 412 (ink recovery port) provided in the liquid circulation unit (the second channel 652 is a channel for recovering liquid from the discharge unit 300). The supply channel 130 and the recovery channel 140 are included in the liquid circulation unit, and the first channel 650 and the second channel 652 of the housing 110 are included in the channel member 520. Furthermore, the second pressure control chamber 152 is connected to the circulation pump 500 via the pump inlet channel 170.

[0029] Next, the flow of ink in the liquid discharge head 1 having the above configuration will be described. The ink supplied to the liquid circulation unit 54 passes through the filter 23 to remove foreign matter such as dust and air bubbles, and then flows into the first valve chamber 121 provided in the first pressure adjustment means 120. The pressure of the ink decreases due to the pressure loss when passing through the filter 23, but the pressure of the ink at this stage is positive. After that, the ink that has flowed into the first valve chamber 121 flows through the communication port 191A and into the first pressure control chamber 122 when the valve 190A is open. Due to the pressure loss when passing through the communication port 191A, the pressure of the ink that has flowed into the first pressure control chamber 122 switches from positive to negative. Next, the flow of ink in the circulation path will be described. The circulation pump 500 operates to send the ink sucked in from the pump inlet passage 170, which is on its upstream side, to the pump outlet passage 180, which is on its downstream side. Therefore, when the pump is driven, the ink supplied to the first pressure control chamber 122 flows into the supply channel 130 and the bypass channel 160 together with the ink delivered from the pump outlet channel 180.

[0030] In this embodiment, a piezoelectric diaphragm pump is used as the liquid-dispensing circulation pump 500, which uses a piezoelectric element attached to a diaphragm as its driving source. The piezoelectric diaphragm pump is a pump that dispenses liquid by changing the volume inside the pump chamber by inputting a driving voltage to the piezoelectric element, causing two check valves to move alternately due to pressure fluctuations. The driving voltage is supplied to the circulation pump 500 via harness wiring 211 by the circulation pump drive circuit (see Figure 6). The piezoelectric diaphragm is located inside the circulation pump 500, and the harness wiring 211 for inputting voltage from the drive circuit is connected to the piezoelectric diaphragm. Therefore, the circulation pump 500 has an opening for the harness wiring 211 connected to the piezoelectric diaphragm. This opening has a sealing portion 501 (see Figure 10), and the sealing portion covers the opening with a sealing member to suppress the intrusion of ink from the outside.

[0031] The ink flowing into the supply channel 130 flows through the supply port 410 and the first channel (650 in Figure 6) of the housing 110 to the common supply channel 18 from the ink supply port of the discharge unit 300. The ink then flows into the pressure chamber 12 via the common supply channel 18. A portion of this incoming ink is discharged from the discharge port 13 by driving the discharge energy generating element (heating element) 15 of the discharge element 310. The remaining ink that is not used for discharge flows through the pressure chamber 12, passes through the common recovery channel 19, and then flows into the recovery channel 140 via the second channel (652 in Figure 6) and recovery port 412 of the housing connected to the discharge unit 300. The ink that flows into the recovery channel 140 flows into the second pressure control chamber 152 of the second pressure adjustment means 150. Meanwhile, ink flowing from the first pressure control chamber 122 into the bypass channel 160 flows into the second valve chamber 151, then passes through the communication port 191B and flows into the second pressure control chamber 152. The ink that has flowed into the second pressure control chamber 152 via the bypass channel 160 and the ink recovered from the recovery channel 140 are drawn into the circulation pump 500 by the drive of the circulation pump 500. The suction is performed through the inlet 170a of the pump inlet channel 170 provided in the second pressure control chamber 152 and then through the pump inlet channel 170. The ink drawn into the circulation pump 500 is then sent to the pump outlet channel 180 and flows back into the first pressure control chamber 122. Subsequently, the ink that has flowed from the first pressure control chamber 122 through the supply channel 130 and the discharge unit 300 into the second pressure control chamber 152, and the ink that has flowed into the second pressure control chamber 152 via the bypass channel 160, both flow into the circulation pump 500. The ink is then sent from the circulation pump 500 to the first pressure control chamber 122. In this way, the ink is circulated within the circulation path.

[0032] As described above, in this embodiment, the circulation pump 500 makes it possible to circulate the liquid along the circulation path formed in the liquid discharge head 1. With this configuration, it is possible to suppress the thickening of the ink and the accumulation of sedimentary components of the colorant ink within the discharge unit 300. As a result, it is possible to maintain good ink fluidity in the discharge unit 300 and good discharge characteristics at the discharge port.

[0033] (Explanation of the circulation pump drive circuit) Figure 6 is a schematic diagram showing the electrical connection configuration for driving the circulation pump. A drive signal is sent from the CPU 400 mounted on the main board 230 in the liquid discharge device to the carriage board 220 in the carriage 53 via a flexible flat cable (FFC). Furthermore, a drive signal is sent from the carriage board 220 to the head electrical board 210 via a connection part 212 with contact connections. Here, the head electrical board 210 is equipped with a control chip, a boost circuit, and a voltage divider circuit. The control chip receives the drive signal and outputs a boost signal, which drives the boost circuit. Here, the input voltage of 5V is boosted to 66V. Boosting the voltage to 66V allows for efficient discharge of air from inside the circulation pump 500. The boosted voltage is output to the circulation pump 500 via the harness wiring 211, driving the circulation pump 500 and circulating the liquid. As explained using Figures 4 and 5, the liquid (ink) is supplied from the first flow path 650 of the housing 110 through the supply port 410 of the liquid circulation unit to the common supply flow path 18 of the discharge unit 300. The liquid (ink) then flows into the pressure chamber 12, and a portion of it is discharged from the discharge port 13. The remaining liquid (ink) that was not used for discharge flows into the circulation unit 54 through the second flow path 652 of the housing 110 connected to the discharge unit 300 and the recovery port 412 of the liquid circulation unit.

[0034] (Explanation of flame retardant measures for high-voltage wiring) Figure 7 is a schematic diagram showing a cross-sectional view of the head electrical circuit board 210. The high-voltage section 620, including high-voltage wiring, is located on the housing side of the liquid discharge head 1, with the core material 600 of the head electrical circuit board 210, which is a flame-retardant material, as the boundary. Current supplied from the main body is connected to the boost circuit 214 of the head electrical circuit board 210 via via holes 630 and boosted. The high-voltage section 620, which is arranged in a two-dimensional plane, is connected to the circulation pump via a connector 610, and the circulation pump 500 is driven. The connector 610 connects the harness wiring 211 from the circulation pump 500 to the high-voltage section 620 via the pump-side connector 211c of the harness wiring 211 and the electrical circuit board connector 210c of the head electrical circuit board 210 (see also Figure 10). As described above, in this embodiment, in order to efficiently discharge the air in the circulation pump 500, the voltage is boosted to 66V in the boost circuit 214. Therefore, a high voltage of 66V is applied to the high-voltage section 620. According to the international safety standard (ICE60950-1), voltages exceeding 42.4V are considered dangerous voltages; therefore, as in this embodiment, it is necessary to prevent users from touching the high-voltage section 620 to which 66V is applied. Furthermore, since the high-voltage section 620 can also be a source of ignition, it is necessary to implement flame retardant measures in case of ignition or smoke emission. In this embodiment, in the head electrical circuit board 210, the high-voltage section 620 is located on the housing side of the liquid discharge head 1, separated by the core material 600; therefore, flame retardant measures are only required on the housing side of the head electrical circuit board 210. Hereinafter, in the description of the circulation pump drive circuit, the liquid discharge head of this disclosure was described as being capable of boosting the voltage up to 66V in the head electrical circuit board 210. However, in light of the above international standard, the head electrical circuit board 210 of the liquid discharge head of this disclosure may have a high-voltage section equipped with high-voltage wiring capable of applying a voltage of at least 42.4V or higher.

[0035] Referring to Figures 8 and 10, the flame retardant measures for the liquid discharge head will be further explained. Figure 8 is a top view of the liquid discharge head 1. Figure 8 shows the liquid circulation unit 54 loaded into the recess 111 of the housing 110, with the pump-side connector 211c of the harness wiring 211 connected to the electrical board connector 210c. As shown in Figure 8, the recess 111 side of the head electrical board 210 has an electrical connection part (composed of the electrical board connector 210c and the pump-side connector 211c) for connecting the circulation pump 500 and the high-voltage unit 620. Figure 10 is a cross-sectional view of Figure 8 XX. As shown in Figure 10, the high-voltage unit 620 on the housing-side surface of the head electrical board 210 is covered to shield it from the outside by the core material of the head electrical board 210 itself, the housing 110, the head cover 60, and the joint member 200. Furthermore, by making these parts from flame retardant materials, the configuration prevents the spread of fire from an ignition source caused by the high-voltage unit 620.

[0036] (Internal structure of the liquid dispensing head) Next, the internal configuration of the liquid discharge head 1 will be described with reference to Figures 9, 10, and 11. Figure 9 is a perspective view showing the upper part of the liquid discharge head 1 with the head cover 60 removed. Figure 10 is a cross-sectional view of Figure 8, taken along line XX. Figure 11 is a cross-sectional view of Figure 10, taken along line XI-XI. First, as shown in Figure 10, the liquid circulation unit 54 is positioned in a recess 111, which is a space formed by the housing 110 and the head cover 60. The housing 110 also has a first side surface 110B and a second side surface 110F. The recess 111 also has at least a side wall 1002 (the side wall of the housing 110 on the side of the first side surface 110B) and a side wall 1002' (the side wall of the housing 110 on the side of the second side surface 110F). In the liquid discharge head of this disclosure, as shown in Figure 10, it is preferable that the height of the circulation unit is higher than the height of the side walls 1002 and 1002' of the housing 110.

[0037] First, let's describe the joint member 200. The joint member 200 is fixed to the second side surface 110F by screws or the like. As shown in Figure 10, the liquid circulation unit 54 is connected to the housing 110 at connection part 112 and to the joint member 200 at connection part 202. The connection part 112 of the housing 110 and the connection part 202 of the joint member 200 are sealed by interposing a sealing member (not shown) between the liquid circulation unit 54 and the joint member 200. Similarly, the space between the liquid circulation unit 54 and the housing 110 is also sealed by interposing a sealing member (not shown).

[0038] The seals at the connection portion 112 of the housing 110 and the connection portion 202 of the joint member 200 can be achieved, for example, by the following configuration.

[0039] The seal between the liquid circulation unit 54 and the housing 110 can be configured such that one side is convex and the other is concave, with the convex side inserted into the concave side, and an O-ring-like sealing member being compressed by the outer circumference of the convex side and the inner circumference of the concave side. Alternatively, a sealing member may be sandwiched between the bottom surface of the liquid circulation unit 54 and the surface of the connection portion 112 of the housing 110 that faces the bottom surface of the liquid circulation unit 54, and the sealing member is compressed by screw fastening.

[0040] The sealing between the liquid circulation unit 54 and the joint member 200 can be carried out in the same way as the sealing between the liquid circulation unit 54 and the housing 110. That is, in this case, for example, one of the liquid circulation unit 54 or the joint member 200 can be made convex and the other concave. Then, the convex shape can be inserted inside the concave shape, and an O-ring press-fit method can be used to press-fit a sealing member such as an O-ring by crushing it with the outer circumference of the convex shape and the inner circumference of the concave shape. Alternatively, at the connection position (connection part 202) between the liquid circulation unit 54 and the joint member 200, a sealing member can be sandwiched between the liquid circulation unit 54 and the joint member 200, and they can be connected by fastening screws so as to crush the sealing member.

[0041] Furthermore, a head cover 60 is located above the liquid circulation unit 54, and the head cover 60 can be fixed to the housing 110 by an engagement portion (not shown).

[0042] Next, the configuration of the housing 110 and the head electrical board 210 will be described. The housing 110 has a first side surface 110B, which is the opposite side surface 110B to the joint member 200 side 110F (second side surface). The head electrical board 210 is mounted on the first side surface 110B. As described above, in order to prevent the user from touching the high-voltage part, the high-voltage part 620 is located on the housing 110 side of the head electrical board 210. An electrical board connector 210c for electrically connecting the circulation pump 500 of the liquid circulation unit 54 and the high-voltage part 620 is located on the housing 110 side of the head electrical board 210.

[0043] More specifically, the recess 111 of the housing 110 has at least a side wall 1002 (the side wall on the first side 110B side of the housing 110) and a side wall 1002' (the side wall on the second side 110F side of the housing 110), as described above. The head electrical board 210 is positioned on the outer surface of the side wall 1002 of the recess 111 (see Figure 10). That is, the head electrical board 210 is mounted so as to face the first side 110B of the side wall 1002.

[0044] As shown in Figure 9, the liquid circulation units 54 (individual liquid circulation units 54a to d) are connected to their respective circulation pumps 500 and have harness wiring 211 equipped with pump-side connectors 211c at their ends. By connecting each pump-side connector 211c to the electrical board connector 210c, the high-voltage section 620 routed to the head electrical board 210 and each circulation pump 500 are electrically connected. The electrical connection section (the part consisting of the electrical board connector 210c and the pump-side connector 211c) is subjected to high voltage, similar to the high-voltage circuit, and therefore must be kept out of the user's reach. For this reason, the electrical connection section is positioned facing inward (inside the recess). A communication section 702 for electrical connection is formed between the head electrical board 210 and the outer surface (first side surface 110B) on the side wall 1002 side of the recess 111, so that the electrical board connector 210c and the pump-side connector 211c can be connected inside the housing 110. As described above, the head electrical circuit board 210 is provided facing the outer surface (first side surface 110B) of the recess 111 on the side wall 1002 side. Therefore, the communication portion 702 is located above this side wall (towards the head cover 60). This communication portion connects the recess 111 and the head electrical circuit board 210. Accordingly, as shown in Figure 10, the electrical connection portion, which consists of the electrical circuit board connector 210c and the pump-side connector 211c, is provided on the head cover 60 side above the upper end 701 of the side wall 1002 (i.e., the electrical connection portion is located above the upper end of the side wall 1002). The electrical connection portion may also be located within the communication portion 702 as shown in Figure 10. Alternatively, it may be located in the space on the side wall 1002 opposite to the inside of the recess 111 (the space between the head electrical circuit board 210 and the side wall 1002).

[0045] Next, the height of the side wall 1002 will be explained using Figure 10 and Figure 11, a cross-sectional view taken along line XI-XI in Figure 10. As shown in Figure 10, the height from the bottom surface 111U of the housing of the recess 111 to the upper end 701 of the side wall 1002 is defined as h1. In other words, the side wall 1002 has a height (h1) from the upper end 701 to the bottom surface 111U of the housing of the recess 111. It is desirable that the housing 110 of the liquid discharge head of this disclosure is configured such that, even if all the ink leaks out from the liquid circulation unit 54, the leaked ink will not reach the communication section 702, and ink will not flow out from the communication section 702 to the head electrical board 210. This configuration makes it possible to suppress ignition and smoke generation due to ink adhering to the high-voltage section 620. Furthermore, as shown in Figure 10, the circulation pump 500 is provided with a sealing section 501 that seals its opening. It is desirable to position the sealing portion 501 higher than h1. This configuration makes it possible to more reliably suppress the intrusion of ink into the circulation pump 500 and prevent ink from adhering to the electrical connection portion of the piezoelectric diaphragm and harness wiring 211.

[0046] Next, with reference to Figure 11, the amount of liquid that can be contained in the recess 111 will be explained. In the liquid ejection head of this disclosure, it is desirable to set the maximum capacity of the recess 111 so that even if liquid such as ink leaks out, ink will not flow out to the head electrical board 210 side. The maximum capacity that can be contained in the recess 111 can be determined, for example, by the following means: With the liquid ejection head in its operating position and with each component (such as the circulation unit) arranged during use, pour liquid into the recess using a beaker or other device capable of measuring volume. The amount of liquid poured up to the point when it begins to leak out of the recess beyond the side wall is the maximum capacity of liquid that can be contained in the recess. Specifically, the maximum capacity of liquid that can be contained in the recess is the volume of the area enclosed by the dashed line in Figure 11, excluding the volume of the area of ​​the liquid circulation unit 54a to d within the dashed line. Note that the maximum capacity of liquid that can be contained in the recess can be determined not only by the physical means described above, but also by calculation.

[0047] In the liquid discharge head of this disclosure, the maximum volume of liquid that can be contained in the recess is made greater than the total volume of liquid that can be contained inside the liquid circulation unit. The total volume of liquid that can be contained inside the liquid circulation unit refers to the liquid contained in the entire flow path (third flow path) connecting the supply port 410 and the recovery port 412 (see, for example, Figure 4) of the liquid circulation unit 54 via a pump.

[0048] Here, the total volume of liquid that can be contained within the liquid circulation unit refers to the sum of the maximum liquid volumes that can be contained in each of the four liquid circulation units 54a to d, as shown in Figure 11. As explained above, the liquid discharge head of this disclosure can accommodate multiple liquid circulation units (four in the above example) in its recess. In addition to the case where multiple liquid circulation units are installed in the liquid discharge head of this disclosure, there may also be only one liquid circulation unit 54, as shown in Figure 12. In this case, the maximum volume of liquid that can be contained in the recess is the volume of the area enclosed by the dashed line in Figure 12, minus the volume of the area within the dashed line of one liquid circulation unit (for example, 54a). The maximum volume of liquid that can be contained in the recess is greater than the maximum volume of liquid that can be contained within one liquid circulation unit.

[0049] Furthermore, it is necessary to consider minimizing the design constraints of the liquid circulation unit 54. For example, to reduce pressure variations in the pressure control unit (first pressure control chamber and second pressure control chamber), it is advisable to consider increasing the volume of the pressure control unit. For this purpose, it is desirable that the maximum liquid capacity that can be contained in the recess 111 under the above-described operating conditions be 10cc or more. Moreover, if ink leaks from multiple individual liquid circulation units 54a to d of the liquid circulation unit 54 and the leaked ink accumulates in the recess 111, and the liquid discharge head 1 is removed, slight vibrations will cause the leaked ink in the recess to oscillate. In such cases, in order to suppress the outflow of ink from the communication section 702, it is more preferable that the maximum liquid capacity that can be contained in the recess 111 under the above-described operating conditions be set to approximately 80cc. In addition, it is even more preferable that the maximum liquid capacity that can be contained in the recess 111 under the above-described operating conditions be in the range of approximately 10cc to approximately 80cc.

[0050] Furthermore, as shown in Figure 10, it is desirable to position the sealing portion 501 that seals the opening of the circulation pump 500 at a position higher than h1. With such a configuration, the intrusion of ink into the inside of the circulation pump 500 can be suppressed more reliably, and ink can be prevented from adhering to the electrical connection part of the piezoelectric diaphragm and harness wiring 211.

[0051] (Second embodiment) Figure 13 shows a second embodiment of the present disclosure. Figure 13 is a schematic cross-sectional view of the liquid discharge head 1 in the second embodiment. As shown in Figure 13, in the liquid discharge head 1 of this embodiment, the head electrical circuit board 210 is located on the upper surface of the head cover 70 (the surface opposite to the side where the recess 111 is located). As shown in Figure 13, the head cover 70 is preferably flat so that the head electrical circuit board 210 can be installed, but the shape of the head cover 70 is not limited thereto. The high-voltage section 620 in the head electrical circuit board 210 is located on the surface of the head electrical circuit board 210 that faces the upper surface of the head cover 70. As shown in Figure 13, the internal space formed by the housing 110, the joint member 200, and the head cover 70 becomes the recess 111 of the liquid circulation unit 54. The head cover 70 has a communication section 802 for connecting the electrical circuit board connector 210c on the head electrical circuit board 210 side and the pump-side connector 211c on the liquid circulation unit 54 side. This communication section 802 is configured such that both the electrical circuit board connector 210c and the pump-side connector 211c do not extend beyond the lower end 801 of the head cover 70 towards the recess 111. In other words, it is configured so that the electrical circuit board connector 210c and the pump-side connector 211c do not protrude beyond the head cover 70 towards the recess.

[0052] As shown in Figure 14, the height from the bottom surface 111U of the housing of the recess 111 to the head cover 70 is defined as h3. In this embodiment, it is preferable that the volume of the area composed of the head cover 70 and the recess 111 is greater than the total volume of liquid in the liquid circulation unit 54. In the housing 110 of the liquid discharge head of this disclosure, it is desirable that the recess 111 be configured such that even if all the ink leaks out from the liquid circulation unit 54, the leaked ink will not reach the head cover 70 and will not flow out from the communication section 802 to the head electrical circuit board 210 side. By configuring it in this way, ignition and smoke generation due to ink adhering to the high-voltage section 620 can be suppressed.

[0053] Next, with reference to Figure 14, the amount of liquid that can be contained in the recess 111 will be explained. In the liquid ejection head of this disclosure, it is desirable to set the maximum capacity of the recess 111 so that even if liquid such as ink leaks out, the ink does not flow out to the side of the head cover where the head electrical circuit board 210 is located. The maximum capacity that can be contained in the recess 111 can be determined, for example, by the following means: With the liquid ejection head in its operating position and with each component (such as the circulation unit) in place during use, pour liquid into the recess using a beaker or other device capable of measuring volume. The amount of liquid poured up to the point when the liquid begins to overflow over the head cover is the maximum capacity of liquid that can be contained in the recess. Specifically, the maximum capacity of liquid that can be contained in the recess is the volume of the area enclosed by the dashed line in Figure 14, minus the volume of the area within the dashed lines of the liquid circulation units 54a to d (the total volume of the four circulation units). Note that the maximum capacity of liquid that can be contained in the recess can be determined not only by the physical means described above, but also by calculation.

[0054] In the liquid discharge head of this disclosure, the maximum volume of liquid that can be contained in the recess is made greater than the total volume of liquid that can be contained inside the liquid circulation unit. The total volume of liquid that can be contained inside the liquid circulation unit refers to the liquid contained in the entire flow path (third flow path) connecting the supply port 410 and the recovery port 412 (see, for example, Figure 4) of the liquid circulation unit 54 via a pump.

[0055] Here, the total liquid capacity that can be contained within the liquid circulation unit refers to the sum of the maximum liquid capacity that can be contained within each of the four liquid circulation units 54a to d, as shown in Figure 14. In this embodiment, the case in which multiple liquid circulation units (four in the above example) are contained within the recess has been described, but in the liquid discharge head of this disclosure, as described using Figure 12 in the first embodiment, there may be only one liquid circulation unit 54. In this case, the volume of the portion enclosed by the dashed line in Figure 14, minus the total volume of one liquid circulation unit (for example, 54a), is the maximum liquid capacity that can be contained within the recess. The maximum liquid capacity that can be contained within the recess is greater than the maximum liquid capacity that can be contained within one liquid circulation unit.

[0056] Another embodiment of this model is described below. This other embodiment is characterized by the provision of a partition wall between the head cover 70 and the recess 111.

[0057] In this embodiment, a partition wall is provided between the head cover and the ceiling position of the recess 111. The partition wall may be a separate component sandwiched between the recess 111 of the housing 110 and the head cover. In this embodiment, the head electrical circuit board 210 is located on the inside of the head cover (housing 110 side) and is provided between it and the partition wall. Therefore, the partition wall partitions the space between the recess 111 and the head electrical circuit board 210. The high-voltage section 620 of the head electrical circuit board 210 is located on the side of the head electrical circuit board 210 that faces the upper surface of the partition wall (head cover side). That is, the high-voltage section 620 is located on the side of the head electrical circuit board 210 that faces the partition wall. The partition wall has a communication section formed therein for connecting the electrical circuit board connector 210c on the head electrical circuit board 210 side and the pump-side connector 211c on the liquid circulation unit 54 side. At this time, the electrical circuit board connector 210c and the pump-side connector 211c are configured so that they do not protrude from the communication section of the partition wall into the recess side. In other words, the electrical circuit board connector 210c and the pump-side connector 211c are configured so that they do not protrude beyond the recessed side of the partition wall.

[0058] In this embodiment, the height from the housing-side bottom surface 111U of the recess 111 to the recess-side surface of the partition wall is defined as h3. In the liquid discharge head of this disclosure, it is preferable that the volume of the area formed by the partition wall and the recess 111 is greater than the volume of liquid in the liquid circulation unit. In this modified example as well, the maximum volume of liquid that can be contained in the recess 111 can be determined by the method described above in this embodiment. With the above configuration, even if ink leaks from the liquid circulation unit 54 inside the recess 111, it is possible to prevent the ink from entering the communication section and to suppress contact between the high-voltage section 620 and the ink. Thus, a partition wall is provided between the head cover 70 and the recess, and the head electrical circuit board 210 is placed between this partition wall and the head bar. This makes it difficult for leaked ink from the liquid circulation unit 54 into the recess 111 to flow out to the head electrical circuit board 210 side, and it is possible to suppress ink from adhering to the high-voltage section 620. As a result, ignition and smoke emission are suppressed.

[0059] (Third embodiment) A third embodiment of the present disclosure will be described with reference to Figure 15. The third embodiment is a configuration in which the discharge port 113 is formed on the bottom surface or side wall of the recess of the housing 110 in the first embodiment.

[0060] As shown in Figure 15, an ink discharge port 113 is provided on the side of the housing 110 opposite to the head electrical board 210 (side wall 1002' side) at a height h2 that is lower than the maximum height h1. By having the discharge port 113 on the opposite side of the head electrical board 210 and at a position lower than the upper end 701 of the communication section 702, leaked ink can be discharged to the outside before it reaches the communication section 702. However, in the event that the high-voltage section ignites and emits smoke due to an unforeseen event other than ink leakage, the opening size of the discharge port 113 cannot be made too large in order to prevent the fire from spreading to the outside. For this reason, it is desirable that the diameter (φ) of the discharge port 113 be approximately 0.8 mm or more and 1.2 mm or less. Thus, the opening size of the discharge port 113 cannot be made too large. Therefore, if ink suddenly leaks, the rate at which ink is discharged to the outside from the outlet 113 may not be sufficient to keep up with the rate at which ink leaks from the liquid circulation unit 54 into the recess 111 of the housing 110, and some ink may accumulate in the recess 111. Furthermore, it is desirable to position the sealing part 501 that seals the opening of the circulation pump 500 at a position higher than h1. With such a configuration, the intrusion of ink into the inside of the circulation pump 500 can be suppressed more reliably, and ink can be prevented from adhering to the electrical connection part of the piezoelectric diaphragm and harness wiring 211.

[0061] In this embodiment, an example is shown in which the discharge port 113 is formed on the second side surface 110F. In the liquid discharge head of this disclosure, it is preferable to form the discharge port 113 on the second side surface 110F, but it may be formed on any side surface of the recess 111 as long as the above requirements for the discharge port are met.

[0062] The liquid discharge head of this disclosure also has the following effects. Specifically, in the configuration of the ink circulation device described in Patent Document 1, the initial voltage is set to 200V, and the diaphragm pump of the device is driven while modulating the voltage within a range of 120V to 300V. Thus, this device uses a relatively high voltage to drive the diaphragm pump. One of the factors that necessitates a high voltage when driving the diaphragm pump is the presence of a large amount of air in the diaphragm pump chamber, such as during initial ink filling. That is, when the diaphragm pump is driven at a low voltage, the displacement of the diaphragm is small, making it difficult to generate pressure in the diaphragm pump chamber and making it difficult to expel the air from the pump chamber. Therefore, it is necessary to drive the diaphragm pump at a high voltage to increase the displacement of the diaphragm and increase the pressure in the pump chamber to expel the air. If a control unit equipped with a drive circuit to which such a relatively high voltage is applied is mounted in a manner that is open to the outside, as in the ink circulation device described in Patent Document 1, there is a risk that the user may come into contact with the high-voltage part. To avoid such risks, it is desirable to configure the system so that the high-voltage component is not located outside the liquid ejection head, but rather directed towards the inside of the liquid ejection head, in order to prevent users from touching the high-voltage component. However, such a configuration requires measures to prevent ink from coming into contact with the high-voltage component if ink leaks inside the liquid ejection head. This disclosure can demonstrate effectiveness even in such situations. [Explanation of symbols]

[0063] 1. Liquid dispensing head 54 Liquid circulation unit 110 cabinets 410 Supply port 412 Collection port 111 recess 111U bottom 650 First channel 652 Second channel 1002, 1002' side wall

[0064] <<Other Embodiments>> The disclosures described in each of the above embodiments include configurations represented by the following examples of liquid dispensing heads and liquid dispensing devices.

[0065] (Composition 1) A liquid dispensing unit for dispensing liquid, A housing having a first channel for supplying liquid to the liquid discharge unit and a second channel for recovering liquid from the liquid discharge unit, A liquid circulation unit having a supply port for supplying liquid to the first flow path, a recovery port for recovering liquid from the second flow path, a pump for supplying the liquid recovered from the recovery port to the supply port, and a third flow path connecting the supply port and the recovery port via the pump, A liquid dispensing head having, The housing has a recess having a bottom surface and a side wall connected to the bottom surface, and the liquid circulation unit is disposed in the recess. A liquid discharge head characterized in that the maximum volume of liquid that can be contained in the recess when the liquid discharge head is in use is greater than the total volume of liquid that can be contained in the third flow path of the liquid circulation unit.

[0066] (Configuration 2) The liquid discharge head according to configuration 1, wherein the liquid discharge head has an electrical circuit board for driving the pump, and the electrical circuit board is disposed on the outer surface of the side wall.

[0067] (Composition 3) The liquid discharge head according to configuration 1 or configuration 2 has a high-voltage section equipped with high-voltage wiring to which a voltage of 42.4V or higher is applied.

[0068] (Composition 4) The high-voltage section is a liquid discharge head according to configuration 3, which is arranged on the surface of the electrical substrate facing the outer surface of the side wall.

[0069] (Composition 5) The liquid discharge head according to any one of configurations 1 to 4, wherein, in the operating state of the liquid discharge head, a part of the liquid circulation unit is located above the upper end of the side wall.

[0070] (Composition 6) The liquid discharge head has a plurality of the liquid circulation units, A liquid discharge head according to any one of configurations 1 to 5, wherein the maximum volume of liquid that can be contained in the recess when the liquid discharge head is in use is greater than the total volume of liquid that can be contained in the third flow path of the plurality of liquid circulation units.

[0071] (Composition 7) The electrical circuit board is a liquid discharge head according to any one of configurations 4 to 6, having an electrical connection portion for connecting the pump and the high-voltage unit.

[0072] (Composition 8) The liquid dispensing head according to configuration 7, wherein the electrical connection portion is located above the upper end of the side wall when the liquid dispensing head is in use.

[0073] (Composition 9) The liquid circulation unit is a liquid discharge head according to any one of configurations 1 to 8, having a plurality of pressure adjustment means.

[0074] (Composition 10) A liquid dispensing head according to any one of configurations 1 to 9, wherein the maximum liquid capacity that can be contained in the recess when the liquid dispensing head is in use is 10cc or more and 80cc or less.

[0075] (Composition 11) A liquid dispensing head according to any one of configurations 1 to 10, having an opening in the bottom surface or side wall of the recess.

[0076] (Composition 12) A liquid dispensing head as described in any one of configurations 1 to 11, An ink tank provided outside the liquid ejection head, A pump provided outside the liquid ejection head, which supplies liquid from the ink tank to the liquid ejection head, A liquid dispensing device equipped with the following features.

Claims

1. A liquid dispensing unit for dispensing liquid, A housing having a first channel for supplying liquid to the liquid discharge unit and a second channel for recovering liquid from the liquid discharge unit, A liquid circulation unit having a supply port for supplying liquid to the first flow path, a recovery port for recovering liquid from the second flow path, a pump for supplying the liquid recovered from the recovery port to the supply port, and a third flow path connecting the supply port and the recovery port via the pump, A liquid dispensing head having, The housing has a recess having a bottom surface and a side wall connected to the bottom surface, and the liquid circulation unit is disposed in the recess. A liquid discharge head characterized in that the maximum volume of liquid that can be contained in the recess when the liquid discharge head is in use is greater than the total volume of liquid that can be contained in the third flow path of the liquid circulation unit.

2. The liquid discharge head according to claim 1, wherein the liquid discharge head has an electrical circuit board for driving the pump, and the electrical circuit board is disposed on the outer surface of the side wall.

3. The liquid discharge head according to claim 1, wherein the electrical circuit board has a high-voltage section equipped with high-voltage wiring to which a voltage of 42.4V or higher is applied.

4. The liquid discharge head according to claim 3, wherein the high-voltage section is arranged on the surface of the electrical substrate facing the outer surface of the side wall.

5. The liquid discharge head according to claim 1, wherein, in the operating state of the liquid discharge head, a part of the liquid circulation unit is located above the upper end of the side wall.

6. The liquid discharge head has a plurality of the liquid circulation units, The liquid discharge head according to claim 1, wherein the maximum volume of liquid that can be contained in the recess when the liquid discharge head is in use is greater than the total volume of liquid that can be contained in the third flow path of the plurality of liquid circulation units.

7. The liquid discharge head according to claim 4, wherein the electrical circuit board has an electrical connection portion for connecting the pump and the high-voltage unit.

8. The liquid dispensing head according to claim 7, wherein the electrical connection portion is located above the upper end of the side wall when the liquid dispensing head is in use.

9. The liquid circulation unit is a liquid discharge head according to claim 1, having a plurality of pressure adjustment means.

10. The liquid dispensing head according to claim 1 or 6, wherein the maximum liquid capacity that can be contained in the recess when the liquid dispensing head is in use is 10 cc or more and 80 cc or less.

11. The liquid dispensing head according to claim 1, having an opening in the bottom surface or side wall of the recess.

12. A liquid dispensing head as described in the claim, An ink tank provided outside the liquid ejection head, A pump provided outside the liquid ejection head, which supplies liquid from the ink tank to the liquid ejection head, A liquid dispensing device equipped with the following features.

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