Liquid dispensing device

Abstract

To improve the operational stability of the liquid dispensing device. [Solution] A liquid dispensing device comprising a liquid storage chamber for storing liquid, a liquid dispensing head having a liquid dispensing unit for dispensing liquid supplied from the liquid storage chamber, a connection part to the liquid dispensing head, and a depressurization mechanism communicating with the connection part, wherein the connection part has a liquid flow path for supplying liquid to the liquid storage chamber and a gas flow path communicating with the depressurization mechanism, the gas flow path is provided with a valve member that can switch the communication of gas between a closed state and an open state, and the depressurization mechanism can pressurize or depressurize a part of the gas flow path to switch the valve member between the closed state and the open state.

Description

Technical Field

[0001] The present invention relates to a liquid ejection device.

Background Art

[0002] In a liquid ejection device, bubbles may be mixed in when replacing a tank or a liquid ejection head. When these bubbles enter the pressure chamber of the liquid ejection head, sufficient pressure for ejecting a liquid such as ink cannot be obtained, which may affect the ejection performance of the liquid. Further, when bubbles remain in the flow path of the liquid ejection head, depending on changes in the external environment of the liquid ejection device, the bubbles may expand and liquid leakage may occur. Therefore, in order to improve the use stability of the liquid ejection device and the liquid ejection head, it is preferable to adopt a configuration that can discharge the bubbles that have entered the inside of the liquid ejection head to the outside.

[0003] Patent Document 1 describes a liquid ejection device having a degassing unit. In the configuration of Patent Document 1, a switching valve is provided between a vacuum pump and a pressure adjustment chamber that is a vacuum target, and the opening and closing between the vacuum pump and the pressure adjustment chamber is switched by controlling the switching valve. Therefore, it is necessary to control the switching valve separately from the pump vacuum operation.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In Patent Document 1, it is necessary to control the switching valve separately from the pump vacuum operation, and the control becomes complicated. Therefore, the present disclosure aims to improve the use stability of the liquid ejection device.

Means for Solving the Problems

[0006] The liquid discharge device of the present invention comprises a liquid discharge head having a liquid discharge unit for discharging liquid supplied from the liquid discharge chamber, a connection portion to the liquid discharge head, and a depressurization mechanism communicating with the connection portion, wherein the connection portion has a liquid flow path for supplying liquid to the liquid discharge chamber and a gas flow path communicating with the depressurization mechanism, the gas flow path is provided with a valve member that can switch the communication of gas between a closed state and an open state, and the valve member can be switched between the closed state and the open state by pressurizing or depressurizing a part of the gas flow path by the depressurization mechanism. [Effects of the Invention]

[0007] According to this disclosure, the operational stability of the liquid dispensing device can be improved. [Brief explanation of the drawing]

[0008] [Figure 1] This is a diagram illustrating a liquid dispensing device. [Figure 2] This is a schematic diagram showing the flow path of the ink supply unit. [Figure 3] This is a schematic diagram illustrating the pressurization process in a pressure chamber. [Figure 4] This is a schematic diagram illustrating the pressurization maintenance process. [Figure 5] This is a schematic diagram illustrating the ink replenishment process. [Figure 6] This is a schematic diagram illustrating the de-aeration and depressurization process. [Figure 7] This is a disassembled perspective view of the liquid dispensing head. [Figure 8] This is a cross-sectional view of the liquid dispensing head and dispensing module. [Figure 9] This is a schematic diagram of the external appearance of the circulation unit. [Figure 10] This is a longitudinal cross-sectional view showing the circulation path. [Figure 11] This is a block diagram schematically showing the circulation path. [Figure 12] This is a cross-sectional view showing an example of a pressure regulating means. [Figure 13]It is an external perspective view of the circulation pump. [Figure 14] It is a sectional view taken along line XIV-XIV of the circulation pump shown in Fig. 13(a). [Figure 15] It is a diagram for explaining the flow of ink in the liquid discharge head. [Figure 16] It is a schematic diagram showing the circulation path in the discharge unit. [Figure 17] It is a diagram showing the opening plate. [Figure 18] It is a diagram showing the discharge element substrate. [Figure 19] It is a sectional view showing the ink flow in the discharge unit. [Figure 20] It is a sectional view showing the vicinity of the discharge port. [Figure 21] It is a sectional view showing a comparative example in the vicinity of the discharge port. [Figure 22] It is a diagram showing a comparative example of the discharge element substrate. [Figure 23] It is a diagram showing the flow path configuration of the liquid discharge head. [Figure 24] It is a diagram schematically showing the backflow of ink in the vicinity of the discharge port. [Figure 25] It is a diagram for explaining the ink supply in the discharge module. [Figure 26] It is a schematic diagram showing the connection state between the main body part of the liquid discharge device and the liquid discharge head. [Figure 27] It is a schematic diagram of the air bleeder unit. [Figure 28] It is a sectional view showing a modified example of the air bleeder unit. [Figure 29] It is a sectional view showing a modified example of the deformation suppression member. [Figure 30] It is a schematic diagram showing a modified example of the deformation suppression member. [Figure 31] It is a schematic diagram showing the operation of the initial filling and air bleeder unit. [Figure 32] It is a diagram schematically showing the first configuration example of the ink path. [Figure 33] It is a diagram schematically showing the first modified example of the circulation path. [Figure 34] This diagram schematically shows the vicinity of a heated circulation pump. [Figure 35] This diagram schematically shows the first modified example of the circulation pathway. [Figure 36] This diagram schematically shows a second modified example of the circulation pathway. [Figure 37] This diagram schematically shows a second modified example of the circulation pathway. [Figure 38] This diagram schematically shows a third modified example of the circulation pathway. [Figure 39] This diagram schematically shows a third modified example of the circulation pathway. [Figure 40] This diagram schematically shows a second example of the ink path configuration. [Figure 41] This diagram schematically shows a fourth modified example of the circulation pathway. [Figure 42] This diagram schematically shows a fourth modified example of the circulation pathway. [Figure 43] This diagram schematically shows a fifth modified example of the circulation pathway. [Figure 44] This diagram schematically shows a fifth modified example of the circulation pathway. [Figure 45] This diagram schematically shows the sixth modified example of the circulation pathway. [Figure 46] This diagram schematically shows the sixth modified example of the circulation pathway. [Figure 47] This block diagram schematically shows other variations of the circulation pathway. [Figure 48] This block diagram schematically shows other variations of the circulation pathway. [Figure 49] This block diagram schematically shows other variations of the circulation pathway. [Figure 50] This is a cross-sectional perspective view of the head-side connecting member. [Figure 51] This is a cross-sectional view showing the state in which the head-side connecting member and the main body-side connecting member are connected. [Figure 52] This is a cross-sectional view showing the closed state of the degassing needle. [Figure 53] This is a cross-sectional view showing the open state of the degassing needle. [Modes for carrying out the invention]

[0009] Preferred embodiments of the present disclosure will be described in detail below with reference to the attached drawings. Note that the following embodiments are not limiting to the present disclosure, and not all combinations of features described in these embodiments are essential to the solutions of the present disclosure. The same reference numerals are used for identical components. In these embodiments, a thermal method is used as the discharge element for discharging liquid, where bubbles are generated by an electrothermal conversion element to discharge the liquid; however, the invention is not limited to this. It can also be applied to liquid discharge heads employing discharge methods that use piezoelectric elements (piezoelectric elements) to discharge liquid, or other discharge methods. Furthermore, the pumps and pressure regulating means described below are not limited to the configurations shown in the embodiments and drawings. The following description will first describe the basic configuration of the present disclosure, and then describe the features of the present disclosure.

[0010] <Liquid discharge device> Figure 1 is a diagram illustrating a liquid ejection device, and is an enlarged view of the liquid ejection head and its surroundings. First, the general configuration of the liquid ejection device 50 in this embodiment will be explained with reference to Figure 1. Figure 1(a) is a schematic perspective view showing a liquid ejection device capable of mounting the liquid ejection head 1. The liquid ejection device 50 in this embodiment constitutes a serial type inkjet recording device that ejects ink as a liquid while scanning the liquid ejection head 1 to record onto a recording medium P.

[0011] The liquid discharge head 1 is mounted on the carriage 60. The carriage 60 reciprocates along the guide axis 51 in the main scanning direction (X direction). The recording medium P is transported by the upstream transport rollers 55, 56 and the downstream transport rollers 57, 58 in the sub-scanning direction (Y direction) which intersects (in this example, is orthogonal to) the main scanning direction. In the figures referenced below, the Z direction represents the vertical direction and intersects (in this example, is orthogonal to) the XY plane defined by the X and Y directions. The liquid discharge head 1 is configured to be removable from and attached to the carriage 60 by the user.

[0012] The liquid discharge head 1 is composed of a circulation unit 54 (see Figure 7), which will be described later, and a discharge unit 3 (see Figure 7). The specific configuration will be described later, but the discharge unit 3 is provided with multiple discharge ports and an energy generating element (hereinafter referred to as a discharge element) that emits discharge energy for discharging liquid from each discharge port.

[0013] The liquid ejection device 50 is also equipped with an ink tank 2, which is the source of the ink, and an ink supply unit 400. The ink stored in the ink tank 2 is supplied to the liquid ejection head 1 by the ink supply unit 400 via a first supply passage 111 and a second supply passage 112. In addition, any gases such as bubbles generated in the liquid ejection head 1 are discharged to the outside of the liquid ejection head 1 by the ink supply unit 400 via a third air passage 113.

[0014] The liquid ejection device 50 forms a predetermined image on the recording medium P by repeatedly performing a recording scan, in which the liquid ejection head 1 mounted on the carriage 60 moves in the main scanning direction and ejects ink for recording, and a transport operation, in which the recording medium P is transported in the sub-scanning direction. In this embodiment, the liquid ejection head 1 is capable of ejecting four types of ink: black (K), cyan (C), magenta (M), and yellow (Y), and it is possible to record a full-color image using these inks. However, the inks that can be ejected from the liquid ejection head 1 are not limited to the above four types of ink. This disclosure is also applicable to liquid ejection heads for ejecting other types of ink. In other words, the types and number of inks ejected from the liquid ejection head are not limited. For example, the number of inks ejected from the liquid ejection head may be one, two, three, or five or more.

[0015] The liquid ejection device 50 is also provided with a control unit 100 and a cap member (not shown) capable of covering the ejection port surface of the liquid ejection head 1. The cap member is positioned in the liquid ejection device 50 away from the transport path of the recording medium P in the X direction. The cap member covers the ejection port surface of the liquid ejection head 1 during non-recording operations and is used to prevent drying of the ejection port, protect it, and for ink suction operations from the ejection port. Signals output from the control unit 100 are transmitted to the liquid ejection head 1, etc., via the signal line 109.

[0016] Figure 1(b) is a block diagram showing the control system of the liquid dispensing device 50. The control unit 100 of the liquid dispensing device 50 includes a CPU 103, RAM 102, ROM 101, a head driver 1A, motor drivers 104A and 105A, and pump drivers 404A and 500A. The CPU 103 functions as a control means that controls the operation of each part of the liquid dispensing device 50 based on a program such as a processing procedure stored in the ROM 101. The RAM 102 is used as a work area when the CPU 103 executes processing. The CPU 103 receives image data from an external host device 900 to control the head driver 1A and controls the driving of the dispensing element provided in the dispensing unit 3. The CPU 103 also controls the drivers of various actuators provided in the liquid dispensing device. For example, the CPU 103 controls the motor driver 104A that drives the transport motor 104 for transporting the recording medium P. The CPU 103 controls the motor driver 105A, which drives the carriage motor 105 for moving the carriage 60. The CPU 103 also controls the pump driver 500A, which drives the circulation pump 500 (described later). The CPU 103 also controls the pump driver 404A, which drives the unidirectional pump 404 (described later). The control unit 100 also receives signals output from various sensors, such as the volume sensor, pressure sensor 409, and liquid sensor 416 (described later). Although Figure 1(b) shows a configuration in which image data received from the host device 900 is processed, processing may be performed in the liquid discharge device 50 without relying on data from the host device 900.

[0017] <Ink Supply Department> Next, the configuration of the ink supply unit 400 will be explained using Figure 2. Figure 2 is a schematic diagram showing the flow path of the ink supply unit 400.

[0018] The ink supply unit 400 has an intermediate tank 401 that temporarily stores ink supplied from an ink tank 2, which is detachably configured to be attached to the liquid ejection device 50, through a first supply passage 111. A first check valve 222 is provided in the middle of the first supply passage 111, and the first check valve 222 restricts the backflow of ink from the intermediate tank 401 to the ink tank 2. At least one surface of the intermediate tank 401 is formed of a flexible membrane 402, and the volume of the intermediate tank 401 can be changed. A volume sensor (not shown) is provided in the intermediate tank 401. The volume sensor can detect the volume of the intermediate tank 401 by measuring the displacement of the flexible membrane 402. From the volume detection result of the volume sensor, it is possible to estimate the amount of ink in the intermediate tank 401. The amount of ink in the intermediate tank 401 may be estimated from the volume detection result of the volume sensor and the amount of ink consumed by the formation of an image on the recording medium, the suction of ink from the cap member, etc.

[0019] The intermediate tank 401 is in contact with an air-filled pressure chamber via a flexible membrane 402. Hereafter, the pressure chamber of the intermediate tank 401 will be referred to as the intermediate pressure chamber 403. By changing the pressure of the gas (air) in the intermediate pressure chamber 403, it is possible to change the pressure of the ink stored in the intermediate tank 401. The ink stored in the intermediate tank 401 is supplied to the liquid discharge head 1 through a second supply passage 112 connected to the intermediate tank 401 and the filter 110 of the liquid discharge head 1. A second check valve 223 is provided in the middle of the second supply passage 112, and the second check valve 223 restricts the backflow of ink from the liquid discharge head 1 to the intermediate tank 401. The ink supply unit 400 has a one-way pump 404 driven by a pump driver 404A. The one-way pump 404 is configured using, for example, a diaphragm pump, and is capable of sucking in and ejecting air in one direction when driven by the pump driver 404A.

[0020] The intermediate pressure chamber 403 and the suction side of the one-way pump 404 are connected via a first air passage 414. A first on-off valve 408 is provided in the middle of the first air passage 414, and the opening and closing operation of the first on-off valve 408 makes it possible to switch between opening and closing the first air passage 414. The first air passage 414 is provided with a first branch air passage 418 that branches off between the first on-off valve 408 and the one-way pump 404, with one end communicating with the atmosphere. A third on-off valve 407 is provided in the first branch air passage 418, and the opening and closing operation of the third on-off valve 407 makes it possible to switch between sealing and opening the suction side of the one-way pump 404 to the atmosphere.

[0021] Furthermore, the intermediate pressure chamber 403 and the ejection side of the one-way pump 404 are connected via a second air passage 415. A second on-off valve 405 is provided in the middle of the second air passage 415, and the opening and closing operation of the second on-off valve 405 makes it possible to switch between opening and closing the second air passage 415. The second air passage 415 is provided with a second branch air passage 419 that branches off between the second on-off valve 405 and the one-way pump 404, with one end communicating with the atmosphere. A fourth on-off valve 406 is provided in the second branch air passage 419, and the opening and closing operation of the fourth on-off valve 406 makes it possible to switch between sealing and opening the ejection side of the one-way pump 404 with the atmosphere. A liquid sensor 416 is provided at the end of the second branch air passage 419 that is open to the atmosphere. The liquid sensor 416 is capable of detecting ink that has entered the air passage. A pressure sensor 409 is provided at one of the positions that communicates with the intermediate pressure chamber 403. The pressure sensor 409 is capable of detecting the pressure of the gas (air) in the intermediate pressure chamber 403. The one-way pump 404 and the depressurization chamber 760 of the de-bubble unit 770 in the liquid discharge head 1, which will be described later, are connected via the third air passage 113. A third check valve 213 is provided in the middle of the third air passage 113, and the third check valve 213 restricts the backflow of gas (air) from the ink supply unit 400 to the depressurization chamber 760.

[0022] Next, the operation of the ink supply unit 400 will be explained using Figures 3 to 6. In this embodiment, the ink supply unit 400 mainly performs four operations (pressure chamber pressurization, pressure maintenance, ink replenishment, and de-bubble de-pressurization) in order to record on the recording medium P. Based on the detection results from a volume sensor (not shown), a pressure sensor 409, etc., the CPU 103 controls the one-way pump 404 and the first to fourth on-off valves to perform the pressure chamber pressurization, pressure maintenance, ink replenishment, and de-bubble de-pressurization operations, which will be described later.

[0023] <Pressure chamber pressurization operation> First, the pressure chamber pressurization operation will be explained using Figure 3. Figure 3 is a schematic diagram illustrating the pressure chamber pressurization operation. In this embodiment, the liquid discharge head 1 is able to discharge ink stably regardless of fluctuations in ink flow rate due to differences in the amount discharged from the liquid discharge head 1, and fluctuations in ink pressure loss due to the viscosity of the ink, etc., because the ink is supplied under pressure. The pressure chamber pressurization operation is an operation to pressurize the ink in the intermediate tank 401 through the flexible membrane 402 by pressurizing the intermediate pressure chamber 403, and to supply the pressurized ink to the liquid discharge head 1 through the second supply passage 112. As the ink in the intermediate tank 401 is consumed and the volume of the intermediate pressure chamber 403 in contact with the intermediate tank 401 via the flexible membrane 402 expands, the gas pressure in the intermediate pressure chamber 403 decreases. Furthermore, when the pressure of the gas in the intermediate pressure chamber 403 is reduced during the ink replenishment operation described later, and then the first on-off valve 408 and the third on-off valve 407 are opened to release the intermediate pressure chamber 403 to the atmosphere, the pressure of the gas in the intermediate pressure chamber 403 becomes atmospheric pressure. In such cases, when the pressure of the gas in the intermediate pressure chamber 403 becomes low, or when the pressure of the gas in the intermediate pressure chamber 403 becomes atmospheric pressure, a pressure chamber pressurization operation is required. The pressure of the gas in the intermediate pressure chamber 403 is monitored by the pressure sensor 409, and if the pressure of the gas in the intermediate pressure chamber 403 is lower than a predetermined pressure required for stable discharge by the liquid discharge head 1, the ink supply unit 400 performs a pressure chamber pressurization operation. When the pressure chamber is pressurized, the ink supply unit 400 operates the unidirectional pump 404 to increase the pressure of the gas in the intermediate pressure chamber 403, with the first on-off valve 408 closed, the second on-off valve 405 open, the third on-off valve 407 open, and the fourth on-off valve 406 closed. When the pressure of the gas in the intermediate pressure chamber 403 increases, the ink in the intermediate tank 401 is pressurized via the flexible membrane 402, and the ink in the second supply passage 112 is pressurized via the second check valve 223, making it possible to supply pressurized ink to the liquid discharge head 1. The pressure of the gas in the intermediate pressure chamber 403 is monitored by the pressure sensor 409, and if the pressure of the gas in the intermediate pressure chamber 403 is above a predetermined pressure, the ink supply unit 400 stops driving the unidirectional pump 404. During this time, the decompression chamber 760 is closed by the third check valve 213, so the pressure inside the decompression chamber 760 is maintained at a low pressure (negative pressure).

[0024] <Pressure maintenance operation> Next, the pressure maintenance operation will be explained using Figure 4. Figure 4 is a schematic diagram illustrating the pressure maintenance operation. The pressure maintenance operation is the operation of maintaining the gas pressure in the intermediate pressure chamber 403, which has risen during the pressure chamber pressurization operation, at a high level. When recording to the recording medium is performed, if the gas pressure in the intermediate pressure chamber 403 is above a predetermined pressure, the ink supply unit 400 performs the pressure maintenance operation. Also, if the gas pressure in the intermediate pressure chamber 403 remains high when the next recording is to begin, it is possible to start the next recording sooner without performing the pressure chamber pressurization operation. Therefore, it is desirable to maintain the gas pressure in the intermediate pressure chamber 403 at a high level. For this reason, even during the waiting time when no recording to the recording medium is performed, if the gas pressure in the intermediate pressure chamber 403 is above a predetermined pressure, the ink supply unit 400 performs the pressure maintenance operation. After the pressure chamber pressurization operation has been performed, if the gas pressure in the intermediate pressure chamber 403 is above a predetermined pressure, the ink supply unit 400 switches to a state where the first on-off valve 408 is closed and the second on-off valve 405 is closed as part of the pressure maintenance operation. At this time, the third on-off valve 407 and the fourth on-off valve 406 may be in a closed state or an open state. This makes it possible to maintain the gas pressure in the intermediate pressure chamber 403, which has risen due to the pressure chamber pressurization operation, at a high pressure. Subsequently, the pressure fluctuation due to the volume change in the intermediate pressure chamber 403 is monitored by the pressure sensor 409, and if the gas pressure in the intermediate pressure chamber 403 is lower than a predetermined pressure, the ink supply unit 400 performs the pressure chamber pressurization operation again. During this time, since the depressurization chamber 760 is closed by the third check valve 213, the pressure in the depressurization chamber 760 is maintained at a low pressure (negative pressure).

[0025] <Ink replenishment operation> Next, the ink replenishment operation will be explained using Figure 5. Figure 5 is a schematic diagram illustrating the ink replenishment operation. The ink replenishment operation is the operation of drawing ink stored in the ink tank 2 into the intermediate tank 401 via the first supply passage 111 when the amount of ink in the intermediate tank 401 falls below a predetermined amount of ink sufficient for recording. Based on the volume detection result of the volume sensor (not shown) of the intermediate tank 401, if the amount of ink in the intermediate tank 401 is less than a predetermined amount of ink sufficient for recording, the ink supply unit 400 performs the ink replenishment operation. During the ink replenishment operation, the ink supply unit 400 opens the first on-off valve 408, closes the second on-off valve 405, closes the third on-off valve 407, and opens the fourth on-off valve 406, and drives the one-way pump 404 to lower the gas pressure in the intermediate pressure chamber 403. When the gas pressure in the intermediate pressure chamber 403 decreases, the ink pressure in the intermediate tank 401 decreases via the flexible membrane 402. By reducing the ink pressure in the intermediate tank 401 to a low pressure (negative pressure), the ink stored in the ink tank 2 can be drawn into the intermediate tank 401 via the first supply passage 111. Based on the volume sensor's detection of the volume of the intermediate tank 401, if the amount of ink in the intermediate tank 401 is greater than or equal to a predetermined amount, the ink supply unit 400 stops driving the one-way pump 404. Furthermore, the ink supply unit 400 opens the first on-off valve 408 and the third on-off valve 407 to open the intermediate pressure chamber 403 to the atmosphere, thereby stopping the drawing of ink into the intermediate tank 401. After opening the intermediate pressure chamber 403 to the atmosphere, the ink supply unit 400 performs the aforementioned pressure chamber pressurization operation to raise the gas pressure in the intermediate pressure chamber 403 from atmospheric pressure. During this time, since the depressurization chamber 760 is closed by the third check valve 213, the pressure in the depressurization chamber 760 is maintained at a low pressure (negative pressure).

[0026] <Bubble removal and depressurization process> Next, the de-bubbling and depressurization operation will be explained using Figure 6. Figure 6 is a schematic diagram illustrating the de-bubbling and depressurization operation. The de-bubbling and depressurization operation is an operation to reduce the pressure inside the depressurization chamber 760. The speed at which gas moves from the foam reservoir chamber 520 of the de-bubbling unit 770 in the liquid discharge head 1 to the depressurization chamber 760 through the gas permeable membrane 710 is proportional to the difference between the pressure inside the foam reservoir chamber 520 and the pressure inside the depressurization chamber 760. For this reason, it is desirable to maintain a low pressure inside the depressurization chamber 760. The inflow of gas from the third air passage 113 to the depressurization chamber 760 is restricted by the third check valve 213 located in the middle of the third air passage 113. However, due to the inflow of gas from the foam reservoir chamber 520 through the gas permeable membrane 710 and the inflow of gas that slightly permeates through the components constituting the depressurization chamber 760, the pressure inside the depressurization chamber 760 gradually increases over time. When the pressure in the depressurization chamber 760 gradually increases over time, a de-bubbling depressurization operation is required to reduce the pressure in the depressurization chamber 760. If it is estimated that the pressure in the depressurization chamber 760 exceeds a predetermined pressure based on the elapsed time since the last de-bubbling depressurization operation, the ink supply unit 400 performs the de-bubbling depressurization operation. During the de-bubbling depressurization operation, the ink supply unit 400 closes the first on-off valve 408, closes the second on-off valve 405, closes the third on-off valve 407, and opens the fourth on-off valve 406, while driving the one-way pump 404 to reduce the pressure in the depressurization chamber 760. If a predetermined time has elapsed since the one-way pump 404 was driven and it is estimated that the pressure in the depressurization chamber 760 is below the predetermined pressure, the ink supply unit 400 stops driving the one-way pump 404. During this time, since the first on-off valve 408 and the second on-off valve 405 are closed, the gas pressure in the intermediate pressure chamber 403 is maintained at a positive pressure. Even if the pressure in the intermediate pressure chamber 403 and the first to third air passages fluctuates due to the aforementioned pressure chamber pressurization operation, pressurization maintenance operation, ink replenishment operation, etc., after the de-bubbling and de-pressurization operation, the pressure in the de-pressurization chamber 760 is maintained at a low pressure (negative pressure) because the third check valve 213 is closed. The de-bubbling and de-pressurization operation in this embodiment is performed once a day. However, it is not limited to this, and the frequency of the de-bubbling and de-pressurization operation may be increased, for example, after arrival or after cleaning when bubbles are likely to form.The frequency of de-aeration and de-pressurization operations may be reduced as time passes after delivery or cleaning. Alternatively, the frequency of de-aeration and de-pressurization operations may be varied depending on temperature, usage conditions, etc.

[0027] <Explanation of head-side connecting component> Figure 50 is an exploded perspective view of the head-side connecting member 800 that connects the circulation unit 54 and the main body-side connecting member 470. The head-side connecting member 800 integrates the degassing passages from each sub-tank into a single passage by joining two members. The joining method is not limited to heat welding, bonding with adhesive, or bonding with molten resin. Instead of providing a separate degassing needle 820 for exhausting bubbles generated from multiple circulation units 54, the degassing passage 830 is integrated and the degassing needle 820 is combined into a single needle, thereby reducing the contact area with the seal portion 910 and reducing the insertion and removal force. In this embodiment, the head-side connecting member 800 is the needle 810 / 820 and the main body-side connecting member 470 is the seal portion, but the combination of the needle 810 / 820 and the seal portion can be reversed.

[0028] Figure 51 is a cross-sectional view showing the state in which the head-side connecting member and the body-side connecting member are connected. In a degassing passage that is not under reduced pressure, the check valve 213 is pressed against the seal portion 910 by the biasing member and sealed, while the ink needle 810 pushes the valve against the biasing force of the biasing member, and the tip of the ink needle 810 is pressed against the valve. Since a notch is provided at the tip of the ink needle 810, ink can be supplied through the notch even when the needle tip is pressed against the valve. When the head-side connecting member is removed, the valve is pressed against the seal portion 910 by the biasing force of the biasing member as the ink needle 810 retracts. This prevents ink from leaking from the body-side connecting member 470 even when the ink needle 810 is removed.

[0029] In this embodiment, the ink needle 810 and the degassing needle 820 of the head-side connecting member have different lengths. Specifically, the degassing needle 820 is shorter than the ink needle 810. Therefore, the degassing needle 820 does not push the check valve 213 (valve), and the degassing passage is sealed. By changing the lengths of the ink needle 810 and the degassing needle 820 and providing a notch only in the ink needle 810, it is possible to give each needle a different function while using common biasing members and valve parts, even when the required biasing force is different. The ink needle and the degassing needle of the main body-side connecting member may also have different lengths.

[0030] <Detailed explanation of check valve operation during de-aeration and pressure reduction> As mentioned above, during the de-aeration and depressurization operation, the one-way pump 404 is driven to reduce the pressure in the depressurization chamber 760 (see Figure 6). A check valve 213 is provided between the one-way pump 404 and the depressurization chamber 760. As shown in Figure 52, the check valve 213 is pressed against the seal portion 910 by a biasing member 930, sealing the degassing passage 830 of the connecting member. As a result, even if the third air passage 113 is pressurized when the one-way pump 404 is pressurized or released to the atmosphere, the check valve 213 seals the degassing passage 830 of the connecting member, so the depressurization chamber 760 is not affected by the pressurization and can maintain a negative pressure state.

[0031] As time passes and the pressure in the depressurization chamber 760 rises, a de-aeration and depressurization operation is performed. The unidirectional pump 404 depressurizes the third air passage 113, and when the force due to the negative pressure in the third air passage 113 exceeds the biasing force of the biasing member, the check valve 213 retracts, as shown in Figure 53, and the pressing state with the seal portion 910 is released. If the unidirectional pump 404 continues the depressurization operation in this state, the depressurization chamber 760 is depressurized via the third air passage 113. When the pressure in the depressurization chamber 760 falls below a predetermined pressure, the depressurization operation of the unidirectional pump 404 stops. When the biasing force of the biasing member 930 exceeds the force due to the negative pressure in the third air passage 113, the check valve 213 moves forward, sealing the degassing passage 830 of the connecting member, as shown in Figure 51, and maintaining the negative pressure in the depressurization chamber 760.

[0032] These actions cause the check valve 213 to operate due to the depressurization, pressurization, or atmospheric release operation of the one-way pump 404, making it possible to maintain the pressure in the depressurization chamber 760 without providing any electrical or other mechanism solely for switching the switching valve in the third air passage 113.

[0033] As described above, as an alternative to the switching valve in Patent Document 1, a valve is provided between the connection part of the liquid discharge head and the pressure reduction mechanism. This valve opens when a portion of the gas flow path is depressurized by a pump, allowing communication with the degassing flow path. This eliminates the need for control components such as switching valves that are solely for opening and closing flow paths, and both degassing and switching the opening and closing of the gas flow path can be performed simultaneously by controlling the pump alone.

[0034] <Liquid dispensing head> Figure 7 is an exploded perspective view of the liquid discharge head 1 of this embodiment. Figure 8 is a cross-sectional view of the liquid discharge head 1 and the discharge module 300. Figure 8(a) is a cross-sectional view of the liquid discharge head 1 shown in Figure 7 along the line VIIIa-VIIIa. Figure 8(b) is an enlarged cross-sectional view of the discharge module 300 shown in Figure 8(a). Hereinafter, the basic configuration of the liquid discharge head 1 in this embodiment will be described, mainly focusing on Figures 7 and 8, with appropriate reference to Figure 1.

[0035] As shown in Figure 7, the liquid ejection head 1 includes a circulation unit 54 and an ejection unit 3 for ejecting ink supplied from the circulation unit 54 onto the recording medium P. In this embodiment, the liquid ejection head 1 is fixedly supported on the carriage 60 of the liquid ejection device 50 by positioning means (not shown) and electrical contacts provided on the carriage 60. The liquid ejection head 1 ejects ink while moving together with the carriage 60 in the main scanning direction (X direction) shown in Figure 1, and records onto the recording medium P.

[0036] The ink supply unit 400, which is connected to the ink tank 2 that serves as the ink supply source, is provided with a first supply passage 111 and a second supply passage 112. A main body-side connecting member 470 (see Figure 26) is provided at the tip of the second supply passage 112. When the liquid discharge head 1 is mounted on the liquid discharge device 50, the main body-side connecting member 470, which is provided at the tip of the second supply passage 112, is detachably connected to a head-side connecting member 800 provided on the head housing 53 of the liquid discharge head 1. This forms an ink supply passage (first supply passage 111 and second supply passage 112) from the ink tank 2 through the ink supply unit 400 to the liquid discharge head 1. In this embodiment, since four types of ink are used, four sets of ink tanks 2, first supply passages 111, second supply passages 112, and circulation units 54 are provided, corresponding to each ink, and four ink supply passages corresponding to each ink are independently formed. As described above, the liquid ejection device 50 of this embodiment is equipped with an ink supply system in which ink is supplied from an ink tank 2 located outside the liquid ejection head 1.

[0037] As shown in Figure 8, the circulation unit 54 includes a circulation unit 54B for black ink, a circulation unit 54C for cyan ink, a circulation unit 54M for magenta ink, and a circulation unit 54Y for yellow ink. Each circulation unit has substantially the same configuration, and in this embodiment, unless otherwise distinguished, each circulation unit will be referred to as circulation unit 54. Although Figure 8 shows an example where the liquid ejection head 1 is equipped with four circulation units 54 corresponding to the four types of ink, it is sufficient to have a circulation unit 54 corresponding to the type of liquid to be ejected. Furthermore, multiple circulation units 54 may be provided for the same type of liquid. In other words, the liquid ejection head 1 can be configured to have one or more circulation units. It is also possible to have a configuration in which only at least one ink is circulated, rather than circulating all four types of ink.

[0038] In Figures 7 and 8(a), the dispensing unit 3 comprises two dispensing modules 300, a first support member 4, a second support member 7, an electrical wiring member (electrical wiring tape) 5, and an electrical contact substrate 6. As shown in Figure 8(b), the dispensing module 300 comprises a silicon substrate 310 with a thickness of 0.5 mm to 1 mm and a plurality of dispensing elements 15 provided on one side of the silicon substrate 310. In this embodiment, the dispensing elements 15 are composed of electrothermal conversion elements (heaters) that generate thermal energy as dispensing energy for dispensing liquid. Power is supplied to each dispensing element 15 via electrical wiring formed on the silicon substrate 310 by film deposition technology.

[0039] Furthermore, an ejection port forming member 320 is formed on the surface of the silicon substrate 310 (the bottom surface in Figure 8(b)). The ejection port forming member 320 has multiple pressure chambers 12 corresponding to multiple ejection elements 15 and multiple ejection ports 13 for ejecting ink, each formed by photolithography technology. In addition, a common supply channel 18 and a common recovery channel 19 are formed on the silicon substrate 310. The silicon substrate 310 also has a supply connection channel 323 connecting the common supply channel 18 to each pressure chamber 12 and a recovery connection channel 324 connecting the common recovery channel 19 to each pressure chamber 12. In this embodiment, one ejection module 300 is configured to eject two types of ink. That is, of the two ejection modules shown in Figure 8(a), the ejection module 300 located on the left side of the figure ejects black ink and cyan ink, and the ejection module 300 located on the right side of the figure ejects magenta ink and yellow ink. Note that this combination is just one example, and any combination of inks is acceptable. One ejection module may eject one type of ink, or it may eject three or more types of ink. The two ejection modules 300 do not have to eject the same number of types of ink. The system may consist of one ejection module 300, or it may consist of three or more ejection modules 300. Furthermore, in the example shown in Figure 8, two rows of ejection ports extending in the Y direction are formed for one color of ink. A pressure chamber 12, a common supply channel 18, and a common recovery channel 19 are formed for each of the multiple ejection ports 13 constituting each row of ejection ports.

[0040] On the back side (top side in Figure 8(b)) of the silicon substrate 310, an ink supply port and an ink recovery port, which will be described later, are formed. The ink supply port supplies ink from the ink supply channel 48 to a plurality of common supply channels 18, and the ink recovery port recovers ink from a plurality of common recovery channels 19 to the ink recovery channel 49.

[0041] The ink supply port and ink recovery port referred to here refer to the openings that supply and recover ink during forward ink circulation, as described later. That is, during forward ink circulation, ink is supplied from the ink supply port to each common supply channel 18, and ink is recovered from each common recovery channel 19 to the ink recovery port. However, there are also cases where ink circulation is performed in the reverse direction. In this case, ink is supplied from the ink recovery port described above to the common recovery channel 19, and ink is recovered from the common supply channel 18 to the ink supply port.

[0042] As shown in Figure 8(a), the ejection module 300 is bonded and fixed to one side of the first support member 4 (the bottom side in Figure 8(a)) on its back surface (the top surface in Figure 8(a)). The first support member 4 has an ink supply channel 48 and an ink recovery channel 49 that penetrate from one side to the other. One opening of the ink supply channel 48 communicates with the aforementioned ink supply port in the silicon substrate 310, and one opening of the ink recovery channel 49 communicates with the aforementioned ink recovery port in the silicon substrate 310. The ink supply channel 48 and the ink recovery channel 49 are provided independently for each type of ink.

[0043] Furthermore, a second support member 7, which has an opening 7a (see Figure 7) through which the ejection module 300 is inserted, is adhesively fixed to one side of the first support member 4 (the lower surface in Figure 8(a)). The second support member 7 holds an electrical wiring member 5 that is electrically connected to the ejection module 300. The electrical wiring member 5 is a component that applies an electrical signal to the ejection module 300 for ejecting ink. The electrical connection between the ejection module 300 and the electrical wiring member 5 is sealed with a sealing material (not shown) to protect it from corrosion by ink and external impacts.

[0044] Furthermore, an electrical contact substrate 6 is thermocompressed to the end 5a (see Figure 7) of the electrical wiring member 5 using an anisotropic conductive film (not shown), and the electrical wiring member 5 and the electrical contact substrate 6 are electrically connected. The electrical contact substrate 6 has an external signal input terminal (not shown) for receiving electrical signals from the liquid dispensing device 50.

[0045] Furthermore, a joint member 8 (Figure 8(a)) is provided between the first support member 4 and the circulation unit 54. The joint member 8 has supply ports 88 and recovery ports 89 formed for each type of ink. The supply ports 88 and recovery ports 89 connect the ink supply channel 48 and ink recovery channel 49 of the first support member 4 with the channels formed in the circulation unit 54. In Figure 8(a), supply ports 88B and recovery ports 89B correspond to black ink, and supply ports 88C and recovery ports 89C correspond to cyan ink. Also, supply ports 88M and recovery ports 89M correspond to magenta ink, and supply ports 88Y and recovery ports 89Y correspond to yellow ink.

[0046] Furthermore, the openings at one end of the ink supply channel 48 and ink recovery channel 49 of the first support member 4 have small opening areas that match the ink supply port and ink recovery port of the silicon substrate 310. In contrast, the openings at the other ends of the ink supply channel 48 and ink recovery channel 49 of the first support member 4 have a shape that is enlarged to the same opening area as the large opening area of ​​the joint member 8 formed to match the flow path of the circulation unit 54. By adopting such a configuration, it is possible to suppress the increase in flow resistance for the ink collected from each recovery channel. However, the shapes of the openings at one end and the other end of the ink supply channel 48 and ink recovery channel 49 are not limited to the above example.

[0047] In the liquid discharge head 1 having the above configuration, the ink supplied to the circulation unit 54 flows through the supply port 88 of the joint member 8 and the ink supply channel 48 of the first support member 4, and then into the common supply channel 18 from the ink supply port of the discharge module 300. Subsequently, the ink flows from the common supply channel 18 into the pressure chamber 12 via the supply connection channel 323, and a portion of the ink that has flowed into the pressure chamber is discharged from the discharge port 13 by the drive of the discharge element 15. The remaining ink that has not been discharged flows from the pressure chamber 12 through the recovery connection channel 324 and the common recovery channel 19, and then into the ink recovery channel 49 of the first support member 4 from the ink recovery port. The ink that has flowed into the ink recovery channel 49 then flows back into the circulation unit 54 via the recovery port 89 of the joint member 8 and is recovered.

[0048] <Components of the circulation unit> Figure 9 is a schematic diagram of the external appearance of one circulation unit 54 corresponding to one type of ink applied to the liquid dispensing device 50 of this embodiment. The circulation unit 54 includes a filter 110, a first pressure regulating means 120, a second pressure regulating means 150, and a circulation pump 500. These components are connected by flow paths as shown in Figures 10 and 11, forming a circulation path within the liquid dispensing head 1 for supplying and recovering ink to the dispensing module 300.

[0049] <Circulation path within the liquid dispensing head> Figure 10 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 10 are simplified. Therefore, the relative positions of each component differ from those in Figure 9. Figure 11 is a schematic block diagram showing the circulation path shown in Figure 10. As shown in Figures 10 and 11, 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 system is configured so that ink flows through the pressure chamber 12 (discharge element 15) 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 discharge head 1 and the flow of ink within the circulation path will be explained below with reference to Figures 10 and 11. The arrows in each figure indicate the direction of ink flow.

[0050] Furthermore, in this embodiment, a foam removal unit 770 is provided inside the liquid discharge head 1, and is configured to discharge foam generated in the liquid discharge head 1 to the outside of the liquid discharge head 1. Figures 10(a) and 10(b) show a configuration in which two foam removal units 770 are provided in different positions, but there may be only one foam removal unit, and its arrangement is not limited to this configuration, as long as it can discharge foam to the outside of the liquid discharge head 1. The specific configuration of the foam removal unit 770 will be described later.

[0051] In the examples shown in Figures 10(a) and 10(b), one of the two de-foaming units 770 is referred to as the first de-foaming unit 770A, and the other of the two de-foaming units 770 is referred to as the second de-foaming unit 770B. As mentioned above, the de-foaming units 770 are not limited to two; one may be provided on the liquid discharge head 1, or three or more may be provided on the liquid discharge head 1. In addition, the first de-foaming unit 770A and the second de-foaming unit 770B are each provided with one foam retention chamber 520, which will be described later. The foam retention chamber 520 provided on the first de-foaming unit 770A is referred to as the first foam retention chamber 520A, and the foam retention chamber 520 provided on the second de-foaming unit 770B is referred to as the second foam retention chamber 520B. In Figure 11, the de-aeration unit 770 and the gas flow path connected to the de-aeration unit 770 (for example, the third air flow path 113, etc.) are not shown.

[0052] First, we will explain the connection status of each component in the liquid dispensing head 1.

[0053] The ink supply unit 400, which supplies ink contained in an external ink tank 2 to the liquid ejection head 1, is connected to the circulation unit 54 via a second supply passage 112 (see Figure 26). A filter 110 is provided in the ink flow path located upstream of the circulation unit 54. The ink supply passage located downstream of the filter 110 (third supply passage 910) 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 10.

[0054] 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 via the aforementioned ink supply port provided in the discharge module 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 that is opened and closed by the valve 190B shown in Figure 10. Figures 10 and 11 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 adjustment means 120, and the other end of the bypass channel 160 is connected to the second valve chamber 151 of the second pressure adjustment means 150. However, 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.

[0055] The second pressure control chamber 152 is connected to the first recovery channel 140. The first recovery channel 140 is connected to the common recovery channel 19 via the aforementioned ink recovery port provided in the discharge module 300. Furthermore, the second pressure control chamber 152 is connected to the circulation pump 500 via the pump inlet channel 170.

[0056] Next, the flow of ink in the liquid ejection head 1 having the above configuration will be described. As shown in Figure 11, the ink contained in the ink tank 2 is pressurized by the one-way pump 404 (see Figure 2) of the ink supply unit 400 provided in the liquid ejection device 50, and supplied to the circulation unit 54 of the liquid ejection head 1 as a positive pressure ink flow.

[0057] The ink supplied to the circulation unit 54 passes through the filter 110 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 110, but the pressure of the ink at this stage is positive. Subsequently, when the valve 190A is open, the ink that has flowed into the first valve chamber 121 passes through the communication port 191A and flows into the first pressure control chamber 122. 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.

[0058] Next, the flow of ink within the circulation path will be explained. The circulation pump 500 operates to send ink drawn 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. The pump inlet passage 170 is located vertically below the second pressure regulating means 150, so that bubbles flowing into the second pressure regulating means 150 from the bypass passage 160 float up without being carried by the ink flow and accumulate vertically above the second pressure regulating means 150. However, the pump inlet passage 170 does not necessarily have to be located vertically below the second pressure regulating means 150; it is acceptable as long as bubbles flowing into the second pressure regulating means 150 float up and are collected in the second bubble accumulation chamber 520B. When the pump is driven, the ink supplied to the first pressure control chamber 122 flows into the supply passage 130 and the bypass passage 160 together with the ink sent from the pump outlet passage 180. As will be explained in more detail later, in this embodiment, a piezoelectric diaphragm pump is used as the circulating pump capable of pumping liquid, with a piezoelectric element attached to the diaphragm as the driving source. A piezoelectric diaphragm pump is a pump that pumps liquid by changing the volume inside the pump chamber by inputting a driving voltage to the piezoelectric element, and by the alternating movement of two check valves due to pressure fluctuations.

[0059] The ink flowing into the supply channel 130 flows from the ink supply port of the ejection module 300 through the common supply channel 18 into the pressure chamber 12, and some of the ink is ejected from the ejection port 13 by the drive (heat generation) of the ejection element 15. The remaining ink that is not used for ejection flows through the pressure chamber 12, passes through the common recovery channel 19, and then flows into the first recovery channel 140 connected to the ejection module 300. The ink that flows into the first recovery channel 140 flows into the second pressure control chamber 152 of the second pressure adjustment means 150.

[0060] 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 first recovery channel 140 are drawn into the circulation pump 500 via the pump inlet channel 170 by the drive of the circulation pump 500. 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 module 300 to 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. Then, they are sent from the circulation pump 500 back into the first pressure control chamber 122. In this way, ink is circulated within the circulation path.

[0061] Here, the flow path connecting the first pressure regulating means 120 and the pressure chamber 12 is referred to as the first flow path, and the flow path connecting the pressure chamber 12 and the circulation pump 500 is referred to as the second flow path. That is, the supply flow path 130 is referred to as the first flow path, and the first recovery flow path 140, the second pressure regulating means 150, and the pump inlet flow path 170 together are referred to as the second flow path. Note that the second flow path does not necessarily have the second pressure regulating means 150 and the pump inlet flow path 170. The pump outlet flow path 180 is also referred to as the third flow path. Therefore, in this embodiment, the ink flows sequentially through the circulation path of the circulation pump 500, the third flow path, the first pressure regulating means 120, the first flow path, the pressure chamber 12, the second flow path, and the circulation pump 500.

[0062] As described above, in this embodiment, the circulation pump 500 makes it possible to circulate the liquid (ink) along the circulation path formed in the liquid discharge head 1. This makes it possible to suppress the thickening of the ink and the accumulation of sedimentary components of the colorant in the discharge module 300, and to maintain good ink fluidity in the discharge module 300 and discharge characteristics at the discharge port.

[0063] Furthermore, since the circulation path in this embodiment is completed within the liquid ejection head 1, the length of the circulation path can be significantly shortened compared to the case where ink is circulated between the ink tank 2 located outside the liquid ejection head and the liquid ejection head 1. As a result, ink circulation can be performed with a small circulation pump.

[0064] Furthermore, the connection channel between the liquid ejection head 1 and the ink tank 2 is configured to include only a channel for supplying ink. In other words, a channel for recovering ink from the liquid ejection head 1 to the ink tank 2 is not required. Therefore, only an ink supply tube is needed to connect the ink tank 2 and the liquid ejection head 1, and there is no need for an ink recovery tube. Consequently, the internal structure of the liquid ejection device 50 can be simplified by reducing the number of tubes, enabling miniaturization of the entire device. Furthermore, by reducing the number of tubes, it is possible to reduce ink pressure fluctuations caused by the oscillation of the tubes during the main scanning of the liquid ejection head 1. In addition, the oscillation of the tubes during the main scanning of the liquid ejection head 1 becomes a driving load for the carriage motor that drives the carriage 60. Therefore, by reducing the number of tubes, the driving load of the carriage motor is reduced, making it possible to simplify the main scanning mechanism including the carriage motor. Furthermore, since it is not necessary to recover ink from the liquid ejection head to the ink tank, it is also possible to miniaturize the one-way pump 404 (see Figure 2) of the ink supply unit 400. Thus, according to this embodiment, it is possible to miniaturize the liquid dispensing device 50 and reduce its cost.

[0065] <Pressure adjustment means> Figure 12 is a cross-sectional view showing an example of a pressure regulating means. Referring to Figure 12, the configuration and operation of the pressure regulating means (first pressure regulating means 120, second pressure regulating means 150) built into the liquid discharge head 1 described above will be explained in more detail. Note that the first pressure regulating means 120 and the second pressure regulating means 150 have substantially the same configuration. For this reason, the first pressure regulating means 120 will be used as an example in the following explanation, and for the second pressure regulating means 150, only the reference numerals for the parts corresponding to the first pressure regulating means in Figure 12 will be added. In the case of the second pressure regulating means 150, the first valve chamber 121 described below will be read as the second valve chamber 151, and the first pressure control chamber 122 will be read as the second pressure control chamber 152.

[0066] The first pressure regulating means 120 has a first valve chamber 121 and a first pressure control chamber 122 formed within a cylindrical housing 125. The first valve chamber 121 and the first pressure control chamber 122 are separated by a partition wall 123 provided within the cylindrical housing 125. However, the first valve chamber 121 communicates with the first pressure control chamber 122 via a communication port 191 formed in the partition wall 123. The first valve chamber 121 is provided with a valve 190 that switches the communication between the first valve chamber 121 and the first pressure control chamber 122 at the communication port 191. The valve 190 is held in a position facing the communication port 191 by a valve spring 200 and is configured to be able to come into close contact with the partition wall 123 by the biasing force of the valve spring 200. When the valve 190 comes into close contact with the partition wall 123, the flow of ink at the communication port 191 is blocked. Furthermore, in order to improve the close contact with the partition wall 123, it is preferable that the contact portion of the valve 190 with the partition wall 123 be formed of an elastic material. In addition, a valve shaft 190s is provided protruding from the center of the valve 190, which is inserted into the communication port 191. By pressing this valve shaft 190s against the biasing force of the valve spring 200, the valve 190 is separated from the partition wall 123, and ink flow becomes possible through the communication port 191. Hereinafter, the state in which the flow of ink through the communication port 191 is blocked by the valve 190 will be referred to as the "closed state," and the state in which ink flow is possible through the communication port 191 will be referred to as the "open state."

[0067] The opening of the cylindrical housing 125 is closed by a flexible member 230 and a pressure plate 210. The flexible member 230, the pressure plate 210, the peripheral wall of the housing 125, and the partition wall 123 form a first pressure control chamber 122. The volume of the first pressure control chamber 122 is variable, and the pressure plate 210 is configured to be displaceable in accordance with the displacement of the flexible member 230. The materials of the pressure plate 210 and the flexible member 230 are not particularly limited, but for example, the pressure plate 210 can be made of a resin molded part and the flexible member 230 can be made of a resin film. In this case, the pressure plate 210 can be fixed to the flexible member 230 by heat welding.

[0068] A pressure adjustment spring 220 (biasing member) is provided between the pressure plate 210 and the partition wall 123. Due to the biasing force of the pressure adjustment spring 220, the pressure plate 210 and the flexible member 230 are biased in a direction that expands the internal volume of the first pressure control chamber 122, as shown in Figure 12(a). Furthermore, when the pressure in the first pressure control chamber 122 decreases, the pressure plate 210 and the flexible member 230 are displaced against the pressure of the pressure adjustment spring 220 in a direction that decreases the internal volume of the first pressure control chamber 122. When the internal volume of the first pressure control chamber 122 decreases to a certain amount, the pressure plate 210 comes into contact with the valve shaft 190s of the valve 190. Subsequently, as the internal volume of the first pressure control chamber 122 decreases further, the valve 190 moves together with the valve shaft 190s against the biasing force of the valve spring 200 and moves away from the partition wall 123. As a result, the communication port 191 is in the open state (state shown in Figure 12(b)).

[0069] In this embodiment, the connection settings within the circulation path are configured such that the pressure in the first valve chamber 121 is higher than the pressure in the first pressure control chamber 122 when the communication port 191 is open. As a result, when the communication port 191 is open, ink flows from the first valve chamber 121 into the first pressure control chamber 122. This ink inflow causes the flexible member 230 and the pressure plate 210 to displace in a direction that increases the internal volume of the first pressure control chamber 122. Consequently, the pressure plate 210 separates from the valve shaft 190s of the valve 190, the valve 190 comes into close contact with the partition wall 123 due to the biasing force of the valve spring 200, and the communication port 191 closes (the state shown in Figure 12(c)).

[0070] Thus, in the first pressure adjustment means 120 of this embodiment, when the pressure in the first pressure control chamber 122 decreases to below a certain pressure (for example, when the negative pressure becomes strong), ink flows in from the first valve chamber 121 through the communication port 191. This prevents the pressure in the first pressure control chamber 122 from decreasing further. Therefore, the first pressure control chamber 122 is controlled to maintain a pressure within a certain range.

[0071] Next, we will explain the pressure in the first pressure control chamber 122 in more detail.

[0072] As described above, consider the state in which the flexible member 230 and the pressure plate 210 are displaced in response to the pressure in the first pressure control chamber 122, and the pressure plate 210 comes into contact with the valve shaft 190s, causing the communication port 191 to open (the state shown in Figure 12(b)). At this time, the relationship of the forces acting on the pressure plate 210 is expressed by the following equation (1). P2×S2+F2+(P1-P2)×S1+F1=0 (1) P1: Pressure (gauge pressure) in the first valve chamber 121 P2: Pressure (gauge pressure) in the first pressure control chamber 122 F1: Spring force of valve spring 200 F2: Spring force of pressure regulating spring 220 S1: Pressure-receiving area of ​​valve 190 S2: Pressure receiving area of ​​pressure plate 210

[0073] Furthermore, rearranging equation (1) for P2 yields the following equation (2). P2=-(F1+F2+P1×S1) / (S2-S1) ···(2)

[0074] Here, the spring force F1 of the valve spring 200 and the spring force F2 of the pressure regulating spring 220 are defined as positive (leftward in Figure 12) when pushing the valve 190 and pressure plate 210. Furthermore, the pressure P1 in the first valve chamber 121 and the pressure P2 in the first pressure control chamber 122 are configured such that P1 ≥ P2.

[0075] The pressure P2 in the first pressure control chamber 122 when the communication port 191 is open is determined by equation (2). When the communication port 191 is open, the system is configured such that P1 ≥ P2, allowing ink to flow from the first valve chamber 121 into the first pressure control chamber 122. As a result, the pressure P2 in the first pressure control chamber 122 is maintained within a certain range without further decrease.

[0076] As shown in Figure 12(c), when the pressure plate 210 is not in contact with the valve shaft 190s and the communication port 191 is closed, the relationship of the forces acting on the pressure plate 210 is expressed by the following equation (3). P3 × S3 + F3 = 0 ... (3) F3: Spring force of the pressure regulating spring 220 when the pressure plate 210 and the valve shaft 190s are not in contact. P3: Pressure (gauge pressure) in the first pressure control chamber 122 when the pressure plate 210 and the valve shaft 190s are not in contact. S3: Pressure receiving area of ​​pressure plate 210 when pressure plate 210 and valve 190 are not in contact.

[0077] Now, rearranging equation (3) for P3, we obtain the following equation (4). P3 = -F3 / S3 ... (4)

[0078] Figure 12(c) shows the state in which the pressure plate 210 and the flexible member 230 have been displaced to the left in the figure to the limit of their displaceability. Depending on the amount of displacement during which the pressure plate 210 and the flexible member 230 are displaced to the state shown in Figure 12(c), the pressure P3 in the first pressure control chamber 122, the spring force F3 of the pressure adjustment spring 220, and the pressure-receiving area S3 of the pressure plate 210 change. Specifically, when the pressure plate 210 and the flexible member 230 are to the right in Figure 12 compared to Figure 12(c), the pressure-receiving area S3 of the pressure plate 210 becomes smaller, and the spring force F3 of the pressure adjustment spring 220 becomes larger. As a result, according to the relationship in equation (4), the pressure P3 in the first pressure control chamber 122 decreases. Therefore, according to equations (2) and (4), the pressure in the first pressure control chamber 122 gradually increases from the state in Figure 12(b) to the state in Figure 12(c) (that is, the negative pressure weakens and approaches the positive pressure). In other words, from the state in which the communication port 191 is open, the pressure plate 210 and the flexible member 230 are gradually displaced to the left, and the pressure in the first pressure control chamber gradually increases until the internal volume of the first pressure control chamber 122 reaches the limit of its displaceability. In other words, the negative pressure weakens. In this embodiment, the first pressure adjustment means 120 adjusts the pressure of the liquid in the first flow path, and the second pressure adjustment means 150 adjusts the pressure of the liquid in the pump inlet flow path 170 (in the inlet flow path).

[0079] <Circulation pump> Next, with reference to Figures 13 and 14, the configuration and operation of the circulation pump 500 built into the liquid discharge head 1 described above will be explained in detail.

[0080] Figure 13 is an external perspective view of the circulation pump 500. Figure 13(a) is an external perspective view showing the front side of the circulation pump 500, and Figure 13(b) is an external perspective view showing the rear side of the circulation pump 500. The outer shell of the circulation pump 500 consists of a pump housing 505 and a cover 507 fixed to the pump housing 505. The pump housing 505 consists of a housing body 505a and a flow path connecting member 505b that is adhesively fixed to the outer surface of the housing body 505a. Each of the housing body 505a and the flow path connecting member 505b is provided with a pair of through holes communicating with each other at two different positions. The pair of through holes provided at one position form the pump supply hole 501, and the pair of through holes provided at the other position form the pump discharge hole 502. The pump supply port 501 is connected to the pump inlet passage 170, which is connected to the second pressure control chamber 152, and the pump discharge port 502 is connected to the pump outlet passage 180, which is connected to the first pressure control chamber 122. The ink supplied from the pump supply port 501 passes through the pump chamber 503 (see Figure 14), which will be described later, and is discharged from the pump discharge port 502.

[0081] Figure 14 is a cross-sectional view of the circulation pump 500 shown in Figure 13(a) along line XIV-XIV. A diaphragm 506 is joined to the inner surface of the pump housing 505, and a pump chamber 503 is formed between the diaphragm 506 and a recess formed on the inner surface of the pump housing 505. The pump chamber 503 communicates with a pump supply hole 501 and a pump discharge hole 502 formed in the pump housing 505. A check valve 504a is provided in the middle portion of the pump supply hole 501, and a check valve 504b is provided in the middle portion of the pump discharge hole 502. In other words, the circulation pump 500 is equipped with check valves in the flow path that connects the second flow path and the third flow path. Specifically, the check valve 504a is positioned so that a part of it can move to the left in the figure within a space 512a formed in the middle portion of the pump supply hole 501. Furthermore, the check valve 504b is positioned so that a portion of it can move to the right in the figure within the space 512b, which is formed in the middle portion of the pump discharge hole 502.

[0082] When the diaphragm 506 is displaced and the volume of the pump chamber 503 increases, causing the pump chamber 503 to be depressurized, the check valve 504a moves away from the opening of the pump supply hole 501 in space 512a (i.e., moves to the left in the figure). When the check valve 504a moves away from the opening of the pump supply hole 501 in space 512a, it becomes an open state that allows ink to flow through the pump supply hole 501. Conversely, when the diaphragm 506 is displaced and the volume of the pump chamber 503 decreases, causing the pump chamber 503 to be pressurized, the check valve 504a comes into close contact with the wall surface surrounding the opening of the pump supply hole 501. As a result, it becomes a closed state that blocks the flow of ink through the pump supply hole 501.

[0083] On the other hand, when the pump chamber 503 is depressurized, the check valve 504b closes to the wall surrounding the opening of the pump housing 505, blocking the flow of ink through the pump discharge hole 502. When the pump chamber 503 is pressurized, the check valve 504b moves away from the opening of the pump housing 505 towards the space 512b (i.e., to the right in the figure), allowing the flow of ink through the pump discharge hole 502.

[0084] Furthermore, the material of each check valve 504a and 504b may be any material that can deform in accordance with the pressure in the pump chamber 503, and can be formed from elastic materials such as EPDM or elastomer, or from films or thin sheets of polypropylene, etc. However, it is not limited to these.

[0085] As mentioned above, the pump chamber 503 is formed by the joint between the pump housing 505 and the diaphragm 506. Therefore, the pressure in the pump chamber 503 changes as the diaphragm 506 deforms. For example, when the diaphragm 506 is displaced toward the pump housing 505 (displaced to the right in the figure) and the volume of the pump chamber 503 decreases, the pressure inside the pump chamber 503 increases. This causes the check valve 504b, which is positioned opposite the pump discharge hole 502, to open, and the ink in the pump chamber 503 is discharged. At this time, the check valve 504a, which is positioned opposite the pump supply hole 501, is in close contact with the wall surface surrounding the pump supply hole 501, so backflow of ink from the pump chamber 503 to the pump supply hole 501 is suppressed.

[0086] Conversely, if the diaphragm 506 is displaced in a direction that expands the pump chamber 503, the pressure in the pump chamber 503 decreases. As a result, the check valve 504a, which is positioned opposite the pump supply hole 501, opens, and ink is supplied to the pump chamber 503. At this time, the check valve 504b, which is positioned at the pump discharge hole 502, comes into close contact with the surrounding wall surface of the opening formed in the pump housing 505, closing the opening. Therefore, backflow of ink from the pump discharge hole 502 to the pump chamber 503 is suppressed.

[0087] In this way, the circulating pump 500 performs ink suction and discharge by deforming the diaphragm 506 and changing the pressure inside the pump chamber 503. However, if bubbles are mixed into the pump chamber 503, even if the diaphragm 506 is displaced, the expansion and contraction of the bubbles will reduce the pressure change inside the pump chamber 503, and the amount of liquid delivered will decrease. Therefore, the pump chamber 503 is positioned parallel to gravity to make it easier for bubbles mixed into the pump chamber 503 to collect at the top of the pump chamber 503, and the pump discharge hole 502 is positioned above the center of the pump chamber 503. This makes it possible to improve the discharge of bubbles inside the pump and stabilize the flow rate.

[0088] <Ink flow within the liquid ejection head> Figure 15 is a diagram illustrating the flow of ink within the liquid ejection head. The circulation of ink within the liquid ejection head 1 will be explained with reference to Figure 15. In order to more clearly explain the ink circulation path, the relative positions of each component (first pressure adjustment means 120, second pressure adjustment means 150, circulation pump 500, etc.) in Figure 15 have been simplified. Therefore, the relative positions of each component differ from those in Figure 9. Figure 15(a) schematically shows the flow of ink when a recording operation is performed, in which ink is ejected from the ejection port 13 to record. The arrows in the figure indicate the flow of ink. In this embodiment, both the ink supply unit 400 and the circulation pump 500 start to drive when a recording operation is performed. Note that the ink supply unit 400 and the circulation pump 500 may be driven regardless of the recording operation. Also, the driving of the ink supply unit 400 and the circulation pump 500 does not have to be performed in conjunction, and they may be driven separately and independently.

[0089] During recording, the circulation pump 500 is ON (operating), and the ink flowing out from the first pressure control chamber 122 flows into the supply channel 130 and the bypass channel 160. The ink that flows into the supply channel 130 passes through the discharge module 300, then flows into the first recovery channel 140, and is subsequently supplied to the second pressure control chamber 152.

[0090] Meanwhile, the ink that flows from the first pressure control chamber 122 into the bypass channel 160 flows into the second pressure control chamber 152 via the second valve chamber 151. The ink that flows into the second pressure control chamber 152 passes through the pump inlet channel 170, the circulation pump 500, and the pump outlet channel 180, and then flows back into the first pressure control chamber 122. At this time, the control pressure by the first valve chamber 121 is set higher than the control pressure of the first pressure control chamber 122, based on the relationship in equation (2) described above. Therefore, the ink in the first pressure control chamber 122 does not flow into the first valve chamber 121 but is supplied again to the discharge module 300 via the supply channel 130. The ink that flows into the discharge module 300 flows back into the first pressure control chamber 122 via the first recovery channel 140, the second pressure control chamber 152, the pump inlet channel 170, the circulation pump 500, and the pump outlet channel 180. Thus, ink circulation that is completed within the liquid discharge head 1 is performed.

[0091] In the ink circulation described above, the amount of ink circulated (flow rate) within the ejection module 300 is determined by the differential pressure of the control pressures between the first pressure control chamber 122 and the second pressure control chamber 152. This differential pressure is set to a circulation amount that suppresses the thickening of the ink near the ejection port within the ejection module 300. In addition, the amount of ink consumed by recording is supplied from the ink tank 2 to the first pressure control chamber 122 via the filter 110 and the first valve chamber 121. The mechanism by which consumed ink is supplied will be explained in detail. As the amount of ink consumed by recording decreases in the circulation path, the pressure in the first pressure control chamber decreases, and as a result, the amount of ink in the first pressure control chamber 122 also decreases. As the amount of ink in the first pressure control chamber 122 decreases, the internal volume of the first pressure control chamber 122 decreases. Due to this decrease in the internal volume of the first pressure control chamber 122, the communication port 191A opens, and ink is supplied from the first valve chamber 121 to the first pressure control chamber 122. As the supplied ink passes from the first valve chamber 121 to the communication port 191A, a pressure loss occurs, and upon flowing into the first pressure control chamber 122, the positive pressure ink switches to a negative pressure state. As ink flows from the first valve chamber 121 into the first pressure control chamber 122, the pressure inside the first pressure control chamber increases, increasing the internal volume of the first pressure control chamber, and the communication port 191A closes. In this way, the communication port 191A repeatedly switches between open and closed states depending on the ink consumption. If no ink is consumed, the communication port 191A remains closed.

[0092] Figure 15(b) schematically shows the ink flow immediately after the recording operation is completed and the circulation pump 500 is turned OFF (stopped). At the time the recording operation is completed and the circulation pump 500 is turned OFF, the pressure in the first pressure control chamber 122 and the pressure in the second pressure control chamber 152 are both at the control pressure during the recording operation. Therefore, ink movement occurs as shown in Figure 15(b) in accordance with the pressure difference between the pressure in the first pressure control chamber 122 and the pressure in the second pressure control chamber 152. Specifically, ink continues to flow from the first pressure control chamber 122 to the discharge module 300 via the supply channel 130, and then through the first recovery channel 140 to the second pressure control chamber 152. In addition, ink continues to flow from the first pressure control chamber 122 to the second pressure control chamber 152 via the bypass channel 160 and the second valve chamber 151.

[0093] The amount of ink that moves from the first pressure control chamber 122 to the second pressure control chamber 152 due to the flow of ink is supplied from the ink tank 2 to the first pressure control chamber 122 via the filter 110 and the first valve chamber 121. Therefore, the volume inside the first pressure control chamber 122 is kept constant. From the relationship in equation (2) described above, when the volume inside the first pressure control chamber 122 is constant, the spring force F1 of the valve spring 200, the spring force F2 of the pressure adjustment spring 220, the pressure receiving area S1 of the valve 190, and the pressure receiving area S2 of the pressure plate 210 are kept constant. Therefore, the pressure in the first pressure control chamber 122 is determined according to the change in the pressure (gauge pressure) P1 in the first valve chamber 121. Thus, if there is no change in the pressure P1 in the first valve chamber 121, the pressure P2 in the first pressure control chamber 122 is kept at the same pressure as the control pressure during recording.

[0094] On the other hand, the pressure in the second pressure control chamber 152 changes over time in accordance with the change in volume due to the inflow of ink from the first pressure control chamber 122. Specifically, from the state shown in Figure 15(b) until the communication port 191 closes and the second valve chamber 151 and the second pressure control chamber 152 become disconnected, as shown in Figure 15(c), the pressure in the second pressure control chamber 152 changes according to equation (2). After that, the pressure plate 210 and the valve shaft 190s become non-contacting, and the communication port 191 closes. Then, as shown in Figure 15(d), ink flows from the first recovery channel 140 into the second pressure control chamber 152. This inflow of ink displaces the pressure plate 210 and the flexible member 230, and the pressure in the second pressure control chamber 152 changes according to equation (4) until the internal volume of the second pressure control chamber 152 reaches its maximum. That is, it rises.

[0095] Furthermore, in the state shown in Figure 15(c), no ink flow occurs from the first pressure control chamber 122 through the bypass passage 160 and the second valve chamber 151 to the second pressure control chamber 152. Therefore, only the flow of ink from the first pressure control chamber 122 to the second pressure control chamber 152 occurs, after it has been supplied to the discharge module 300 via the supply passage 130 and then through the first recovery passage 140. As mentioned above, the movement of ink from the first pressure control chamber 122 to the second pressure control chamber 152 occurs in accordance with the pressure difference between the pressure in the first pressure control chamber 122 and the pressure in the second pressure control chamber 152. For this reason, when the pressure in the second pressure control chamber 152 becomes equal to the pressure in the first pressure control chamber 122, the movement of ink stops.

[0096] Furthermore, when the pressure in the second pressure control chamber 152 becomes equal to the pressure in the first pressure control chamber 122, the second pressure control chamber 152 expands to the state shown in Figure 15(d). When the second pressure control chamber 152 expands as shown in Figure 15(d), a storage section capable of storing ink is formed in the second pressure control chamber 152. The time from stopping the circulation pump 500 to transitioning to the state shown in Figure 15(d) may vary depending on the shape and size of the flow path and the properties of the ink, but it generally takes about 1 to 2 minutes. When the circulation pump 500 is driven from the state shown in Figure 15(d) with ink stored in the storage section, the ink in the storage section is supplied to the first pressure control chamber 122 by the circulation pump 500. As a result, as shown in Figure 15(e), the amount of ink in the first pressure control chamber 122 increases, and the flexible member 230 and the pressure plate 210 are displaced in the expansion direction. Then, as the circulation pump 500 continues to operate, the conditions within the circulation path will change, as shown in Figure 15(a).

[0097] In the above explanation, Figure 15(a) was used as an example during recording, but as mentioned above, ink circulation may occur without recording. Even in this case, the ink flow shown in Figures 15(a) to (e) will occur in response to the driving and stopping of the circulation pump 500.

[0098] As mentioned above, in this embodiment, the communication port 191B in the second pressure adjustment means 150 is shown as being open when the circulation pump 500 is driven and ink is circulated, and closed when ink circulation stops, but it is not limited to this. The control pressure may be set so that the communication port 191B in the second pressure adjustment means 150 is closed even when the circulation pump 500 is driven and ink is circulated. The role of the bypass passage 160 will be explained in detail below.

[0099] The bypass channel 160 connecting the first pressure adjustment means 120 and the second pressure adjustment means 150 is provided to prevent the discharge module 300 from being affected, for example, when the negative pressure generated in the circulation path becomes stronger than a predetermined value. The bypass channel 160 is also provided to supply ink to the pressure chamber 12 from both sides of the supply channel 130 and the first recovery channel 140.

[0100] First, we will explain an example in which a bypass flow path 160 is provided to prevent the negative pressure from affecting the discharge module 300 when it exceeds a predetermined value. For example, the properties of the ink (e.g., viscosity) may change due to changes in ambient temperature. When the viscosity of the ink changes, the pressure loss in the circulation path also changes. For example, if the viscosity of the ink decreases, the pressure loss in the circulation path decreases. As a result, the flow rate of the circulation pump 500, which is driven at a constant drive amount, increases, and the flow rate through the discharge module 300 increases. On the other hand, since the discharge module 300 is kept at a constant temperature by a temperature control mechanism (not shown), the viscosity of the ink in the discharge module 300 is kept constant even if the ambient temperature changes. As the flow rate of the ink flowing through the discharge module 300 increases while the viscosity of the ink in the discharge module 300 does not change, the negative pressure in the discharge module 300 increases due to flow resistance. In this way, if the negative pressure in the discharge module 300 exceeds a predetermined value, the meniscus of the discharge port 13 may be destroyed, drawing in outside air into the circulation path and potentially preventing normal discharge. Even if the meniscus is not destroyed, the negative pressure in the pressure chamber 12 may exceed a predetermined value, potentially affecting the discharge.

[0101] Therefore, in this embodiment, a bypass channel 160 is formed within the circulation path. By providing the bypass channel 160, ink flows through the bypass channel 160 when the negative pressure exceeds a predetermined value, thus maintaining a constant pressure in the discharge module 300. Accordingly, for example, the communication port 191B in the second pressure adjustment means 150 may be configured with a control pressure that maintains a closed state even when the circulation pump 500 is running. Furthermore, the control pressure in the second pressure adjustment means may be set so that the communication port 191 in the second pressure adjustment means 150 opens when the negative pressure exceeds a predetermined value. In other words, as long as the meniscus does not collapse due to changes in the flow rate of the pump caused by viscosity changes such as environmental changes, or as long as a predetermined negative pressure is maintained, the communication port 191B may be in a closed state when the circulation pump 500 is running.

[0102] Next, we will describe an example in which a bypass channel 160 is provided to supply ink to the pressure chamber 12 from both sides of the supply channel 130 and the first recovery channel 140. Pressure fluctuations in the circulation path can also be caused by the ejection operation of the ejection element 15, because the ejection operation generates a force that draws ink into the pressure chamber.

[0103] The following explains that when recording at a high duty cycle, the ink supplied to the pressure chamber 12 is supplied from both the supply channel 130 and the first recovery channel 140. Note that the definition of duty cycle can vary depending on various conditions, but here, we will treat the state where a single 4pl ink droplet is ejected onto a 1200dpi grid and recorded as 100%. Recording at a high duty cycle means, for example, recording at a 100% duty cycle.

[0104] If a high duty cycle is maintained, the amount of ink flowing from the pressure chamber 12 into the second pressure control chamber 152 through the first recovery channel 140 decreases. On the other hand, the circulation pump 500 discharges ink at a constant rate, disrupting the balance between inflow and outflow within the second pressure control chamber 152. This reduces the amount of ink in the second pressure control chamber 152, increasing the negative pressure within it and causing it to shrink. As the negative pressure within the second pressure control chamber 152 increases, the amount of ink flowing into the second pressure control chamber 152 via the bypass channel 160 increases, and the second pressure control chamber 152 stabilizes with a balance between inflow and outflow. Thus, as a result, the negative pressure within the second pressure control chamber 152 increases in accordance with the duty cycle. Furthermore, as described above, in a configuration where the communication port 191B is closed when the circulation pump 500 is running, the communication port 191B will open according to the duty cycle, and ink will flow from the bypass flow path 160 into the second pressure control chamber 152.

[0105] As the duty cycle continues to be higher, the amount of ink flowing from the pressure chamber 12 to the second pressure control chamber 152 through the first recovery channel 140 decreases, while the amount of ink flowing into the second pressure control chamber 152 through the bypass channel 160 and the communication port 191B increases. If this condition progresses further, the amount of ink flowing from the pressure chamber 12 to the second pressure control chamber 152 through the first recovery channel 140 becomes zero, and all the ink flowing out to the circulation pump 500 becomes ink flowing in from the communication port 191B. If this condition progresses further, ink now flows back from the second pressure control chamber 152 to the pressure chamber 12 through the first recovery channel 140. In this state, the ink flowing out of the second pressure control chamber 152 to the circulation pump 500 and the ink flowing out to the pressure chamber 12 flow into the second pressure control chamber 152 through the bypass channel 160 and the communication port 191B. In this case, the pressure chamber 12 will be filled with ink from the supply channel 130 and ink from the first recovery channel 140, and then discharged.

[0106] Furthermore, the ink backflow that occurs when the recording duty cycle is high is a phenomenon caused by the provision of the bypass channel 160. In addition, although the above describes an example in which the communication port 191B in the second pressure adjustment means opens in response to ink backflow, ink backflow may also occur when the communication port 191B in the second pressure adjustment means is open. Moreover, even in a configuration without a second pressure adjustment means, the above-mentioned ink backflow can occur due to the provision of the bypass channel 160. The bypass channel 160 only needs to connect at least one of the first channel or the first pressure adjustment means 120 to the second channel without going through the pressure chamber 12.

[0107] <Discharge Unit Configuration> Figure 16 is a schematic diagram showing the circulation path for one ink color in the ejection unit 3 of this embodiment. Figure 16(a) is an exploded perspective view of the ejection unit 3 as seen from the first support member 4 side, and Figure 16(b) is an exploded perspective view of the ejection unit 3 as seen from the ejection module 300 side. The arrows labeled IN and OUT in the figure indicate the flow of ink, and although only the flow for one color is explained, the flow for other colors is similar. Also, the description of the second support member 7 and the electrical wiring member 5 is omitted in Figure 16, and this omission is also omitted in the following description of the ejection unit configuration. Furthermore, the first support member 4 in Figure 16(a) is shown as a cross-section at XVI-XVI in Figure 8. As mentioned above, the ejection module 300 comprises a silicon substrate 310 and a plurality of ejection elements 15. The silicon substrate 310 comprises an ejection element substrate 340 and an opening plate 330. Figure 17 shows the opening plate 330, and Figure 18 shows the ejection element substrate 340.

[0108] Ink is supplied to the discharge unit 3 from the circulation unit 54 via the joint member 8 (see Figure 8(a)). The ink path from when the ink passes through the joint member 8 until it returns to the joint member 8 will be described below. Note that the joint member 8 is not shown in the following drawings.

[0109] The ejection module 300 comprises an ejection element substrate 340 and an opening plate 330 that constitute a silicon substrate 310, and further comprises an ejection port forming member 320. The ejection element substrate 340, the opening plate 330, and the ejection port forming member 320 are joined together by overlapping so that the flow paths of each ink are in communication, forming the ejection module 300, which is supported by the first support member 4. The ejection unit 3 is formed when the ejection module 300 is supported by the first support member 4. The ejection port forming member 320 is provided on the surface of the ejection element substrate 340 (the lower surface in Figure 16(b)). The ejection port forming member 320 has multiple rows of ejection ports 13 arranged in a row, and ejects a portion of the ink supplied through the ink flow paths in the ejection module 300 from the ejection ports 13. The ink that is not ejected is recovered through the ink flow paths in the ejection module 300.

[0110] As shown in Figures 16 and 17, the opening plate 330 is provided with a plurality of arranged ink supply ports 311 and a plurality of arranged ink recovery ports 312. As shown in Figures 18 and 19, the ejection element substrate 340 is provided with a plurality of arranged supply connection channels 323 and a plurality of arranged recovery connection channels 324. Furthermore, the ejection element substrate 340 is provided with a common supply channel 18 that communicates with the plurality of supply connection channels 323 and a common recovery channel 19 that communicates with the plurality of recovery connection channels 324. The ink channels within the ejection unit 3 are formed by connecting the ink supply channels 48 and ink recovery channels 49 (see Figure 8(a)) provided in the first support member 4 with the channels provided in the ejection module 300. The support member supply port 211 is a cross-sectional opening that forms the ink supply channel 48, and the support member recovery port 212 is a cross-sectional opening that forms the ink recovery channel 49.

[0111] The ink supplied to the discharge unit 3 is supplied from the circulation unit 54 (see Figure 8(a)) to the ink supply channel 48 (see Figure 8(a)) of the first support member 4. The ink that flows through the support member supply port 211 in the ink supply channel 48 is supplied to the common supply channel 18 of the discharge element substrate 340 via the ink supply channel 48 (see Figure 8(a)) and the ink supply port 311 of the opening plate 330, and enters the supply connection channel 323. This is the supply side channel. After that, the ink flows through the pressure chamber 12 (see Figure 8(b)) of the discharge port forming member 320 to the recovery side channel, the recovery connection channel 324. Details of the ink flow in the pressure chamber 12 will be described later.

[0112] In the recovery channel, ink that enters the recovery connection channel 324 of the ejection element substrate 340 flows into the common recovery channel 19. Subsequently, the ink flows from the common recovery channel 19 through the ink recovery port 312 of the opening plate 330 to the ink recovery channel 49 of the first support member 4, and is recovered in the circulation unit 54 via the support member recovery port 212.

[0113] The area of ​​the opening plate 330 that does not have an ink supply port 311 or an ink recovery port 312 corresponds to the area of ​​the first support member 4 that partitions the support member supply port 211 and the support member recovery port 212. Furthermore, the first support member 4 also does not have an opening in this area. Such an area is used as the bonding area when bonding the discharge module 300 and the first support member 4.

[0114] As shown in Figure 17, the opening plate 330 has multiple rows of openings arranged in the X direction and multiple rows of openings arranged in the Y direction, with supply (IN) openings and recovery (OUT) openings arranged alternately in the Y direction with a half-pitch offset in the X direction. The supply (IN) opening is formed by the ink supply port 311, and the recovery (OUT) opening is formed by the ink recovery port 312. As shown in Figure 18, the ejection element substrate 340 has a common supply channel 18 that communicates with multiple supply connection channels 323 arranged in the Y direction, and a common recovery channel 19 that communicates with multiple recovery connection channels 324 arranged in the Y direction, arranged alternately in the X direction. The common supply channels 18 and common recovery channels 19 are separated by ink type, and the number of common supply channels 18 and common recovery channels 19 is determined according to the number of ejection port rows for each color. In addition, the supply connection channels 323 and recovery connection channels 324 are arranged in a number corresponding to the number of ejection ports 13. Furthermore, a one-to-one correspondence is not necessarily required; one supply connection channel 323 and one recovery connection channel 324 may correspond to multiple discharge ports 13.

[0115] When the opening plate 330 and the ejection element substrate 340 are joined together so that the flow paths of each ink are in communication, they form an ejection module 300, which is then supported by the first support member 4, thereby forming an ink flow path with the supply flow path and recovery flow path described above.

[0116] Figure 19 is a cross-sectional view showing the ink flow in different parts of the ejection unit 3. Figure 19(a) is the cross-section shown from XIXa to XIXa in Figure 16(a), showing the cross-section of the part of the ejection unit 3 where the ink supply channel 48 and the ink supply port 311 are in communication. Figure 19(b) is the cross-section shown from XIXb to XIXb in Figure 16(a), showing the cross-section of the part of the ejection unit 3 where the ink recovery channel 49 and the ink recovery port 312 are in communication. Figure 19(c) is the cross-section shown from XIXc to XIXc in Figure 16(a), showing the cross-section of the part where the ink supply port 311 and the ink recovery port 312 are not in communication with the channel of the first support member 4.

[0117] In the ink supply channel, as shown in Figure 19(a), ink is supplied from the portion where the ink supply channel 48 of the first support member 4 and the ink supply port 311 of the opening plate 330 overlap and communicate. In the ink recovery channel, as shown in Figure 19(b), ink is recovered from the portion where the ink recovery channel 49 of the first support member 4 and the ink recovery port 312 of the opening plate 330 overlap and communicate. Also, as shown in Figure 19(c), in the ejection unit 3, there are areas where the opening plate 330 does not have an opening. In such areas, ink is not supplied or recovered between the ejection element substrate 340 and the first support member 4. Ink is supplied in the area where the ink supply port 311 is provided, as shown in Figure 19(a), and ink is recovered in the area where the ink recovery port 312 is provided, as shown in Figure 19(b). In this embodiment, a configuration using the opening plate 330 has been described as an example, but a configuration without the opening plate 330 may also be used. For example, the first support member 4 may have channels corresponding to the ink supply channel 48 and the ink recovery channel 49, and the ejection element substrate 340 may be bonded to the first support member 4.

[0118] Figures 20(a) and 20(b) are cross-sectional views showing the vicinity of the discharge port 13 in the discharge module 300. Figures 21(a) and 21(b) are cross-sectional views showing a discharge module with a configuration in which the common supply channel 18 and common recovery channel 19 are extended in the X direction, as a comparative example. The thick arrows shown in the common supply channel 18 and common recovery channel 19 in Figures 20(a) and 20(b), and Figures 21(a) and 21(b) indicate the oscillation of the ink in a configuration using a serial-type liquid discharge device 50. The ink supplied to the pressure chamber 12 via the common supply channel 18 and the supply connection channel 323 is discharged from the discharge port 13 when the discharge element 15 is driven. If the discharge element 15 is not driven, the ink is recovered from the pressure chamber 12 through the recovery connection channel 324, which is a recovery channel, to the common recovery channel 19.

[0119] In a configuration using a serial-type liquid ejection device 50, when ejection is performed from circulating ink in this manner, the ejection of ink is inevitably affected to some extent by the oscillation of the ink in the ink flow path caused by the main scanning of the liquid ejection head 1. Specifically, the effect of the oscillation of the ink in the ink flow path may manifest as differences in the amount of ink ejected or deviations in the ejection direction. As shown in Figures 21(a) and (b), if the common supply flow path 18 and the common recovery flow path 19 have a wide cross-sectional shape in the X direction, which is the main scanning direction, the ink in the common supply flow path 18 and the common recovery flow path 19 becomes more susceptible to inertial force in the main scanning direction, causing large oscillations in the ink. As a result, there is a risk that the oscillation of the ink may affect the ejection of ink from the ejection port 13. Furthermore, if the common supply flow path 18 and the common recovery flow path 19 are widened in the X direction, the distance between colors will increase, which may reduce printing efficiency.

[0120] Therefore, in this embodiment, the common supply channel 18 and common recovery channel 19 extend in the Y direction in the cross-sections shown in Figures 20(a) and 20(b), but are also configured to extend in the Z direction, which is perpendicular to the X direction, which is the main scanning direction. This configuration makes it possible to reduce the width of each channel in the common supply channel 18 and common recovery channel 19 in the main scanning direction. By reducing the width of each channel in the common supply channel 18 and common recovery channel 19 in the main scanning direction, the oscillation of the ink due to the inertial force acting on the ink in the common supply channel 18 and common recovery channel 19 in the opposite direction to the main scanning direction during main scanning (see the thick black arrow in the figure) is reduced. This makes it possible to suppress the effect of ink oscillation on ink discharge. In addition, by extending the common supply channel 18 and common recovery channel 19 in the Z direction, the cross-sectional area of ​​the common supply channel 18 and common recovery channel 19 is increased, reducing flow pressure loss.

[0121] As described above, the common supply channel 18 and the common recovery channel 19 are configured to reduce the oscillation of ink within them during main scanning by reducing the width of each channel in the main scanning direction, but this does not eliminate ink oscillation entirely. In this embodiment, in order to suppress differences in the ejection of different ink types that may still occur even with reduced ink oscillation, the common supply channel 18 and the common recovery channel 19 are configured to be positioned in an overlapping position with respect to the X direction.

[0122] As described above, in this embodiment, the supply connection channel 323 and the recovery connection channel 324 are provided corresponding to the discharge port 13, and the supply connection channel 323 and the recovery connection channel 324 are arranged side by side in the X direction with the discharge port 13 in between. Therefore, there is a portion where the common supply channel 18 and the common recovery channel 19 do not overlap in the X direction, and if the correspondence between the supply connection channel 323 and the recovery connection channel 324 in the X direction is disrupted, it will affect the flow and discharge of ink in the X direction in the pressure chamber 12. If the effect of ink oscillation is added to this, it may further affect the discharge of ink at each discharge port.

[0123] Therefore, by arranging the common supply channel 18 and the common recovery channel 19 in positions that overlap with respect to the X direction, the ink oscillation during main scanning in the common supply channel 18 and the common recovery channel 19 becomes almost the same at any position in the Y direction where the discharge ports 13 are arranged. As a result, the pressure difference between the common supply channel 18 side and the common recovery channel 19 side that occurs in the pressure chamber 12 does not fluctuate significantly, and stable discharge can be achieved.

[0124] Furthermore, in some liquid ejection heads that circulate ink, the flow path for supplying ink to the liquid ejection head and the flow path for recovering ink are configured as the same flow path. However, in this embodiment, the common supply flow path 18 and the common recovery flow path 19 are separate flow paths. The supply connection flow path 323 and the pressure chamber 12 are in communication, and the pressure chamber 12 and the recovery connection flow path 324 are in communication, and ink is ejected from the discharge port 13 of the pressure chamber 12. In other words, the pressure chamber 12, which is the path connecting the supply connection flow path 323 and the recovery connection flow path 324, is configured to have a discharge port 13. Therefore, an ink flow occurs in the pressure chamber 12 from the supply connection flow path 323 side to the recovery connection flow path 324 side, and the ink in the pressure chamber 12 is efficiently circulated. By efficiently circulating the ink in the pressure chamber 12, the ink in the pressure chamber 12, which is susceptible to the effects of ink evaporation from the discharge port 13, can be kept in a fresh state.

[0125] Furthermore, since both the common supply channel 18 and the common recovery channel 19 are connected to the pressure chamber 12, if it becomes necessary to discharge at a high flow rate, it is possible to supply ink from both channels. In other words, compared to a configuration in which ink supply and recovery are handled by only one channel, the configuration in this embodiment has the advantage of not only enabling efficient circulation but also being able to handle high flow rate discharge.

[0126] Furthermore, the common supply channel 18 and the common recovery channel 19 should be located closer together in the X direction to minimize the effects of ink sloshing. Preferably, the distance between the channels should be 75 μm to 100 μm.

[0127] Figure 22 shows a comparative example of an ejection element substrate 340. Note that the supply connection channel 323 and the recovery connection channel 324 are omitted in Figure 22. Ink that has received thermal energy from the ejection element 15 in the pressure chamber 12 flows into the common recovery channel 19, so ink that is relatively hotter than the ink in the common supply channel 18 flows through it. In this case, as shown in part α enclosed by the dashed line in Figure 22, there is a part of the ejection element substrate 340 in the X direction where only the common recovery channel 19 exists. In this case, the temperature rises locally in that part, causing temperature unevenness within the ejection module 300, which may affect the ejection process.

[0128] Ink at a relatively lower temperature flows through the common supply channel 18 compared to the common recovery channel 19. Therefore, if the common supply channel 18 and the common recovery channel 19 are adjacent to each other, some of the temperatures in the vicinity cancel each other out, thus suppressing the temperature rise. For this reason, it is preferable that the common supply channel 18 and the common recovery channel 19 are adjacent to each other, overlapping in the X direction with approximately the same length.

[0129] Figures 23(a) and 23(b) show the flow path configuration of a liquid ejection head that corresponds to three types of ink: cyan (C), magenta (M), and yellow (Y). In a liquid ejection head that corresponds to three types of ink, a circulation flow path is provided for each type of ink, as shown in Figure 23(a). The pressure chamber 12 is provided along the X direction, which is the main scanning direction of the liquid ejection head. Also, as shown in Figure 23(b), the common supply flow path 18 and the common recovery flow path 19 are provided along the row of ejection ports 13, and extend in the Y direction so as to sandwich the row of ejection ports between the common supply flow path 18 and the common recovery flow path 19.

[0130] <Ink backflow near the discharge port> Figure 24 schematically illustrates the backflow of ink near the discharge port. Figure 24(a) is a longitudinal cross-sectional view schematically showing the backflow of ink occurring in the circulation path shown in Figure 10(a), and Figure 24(b) is an enlarged view schematically showing the backflow of ink occurring in the discharge module 300 shown in Figure 8(b). Figures 24(a) and 24(b) show the flow of ink in the pressure chamber 12, which flows in from the common supply channel 18 or the common recovery channel 19, passes through the pressure chamber 12, and flows out from the discharge port 13. As mentioned above, when recording at a high duty cycle, ink also flows back into the pressure chamber 12 from the first recovery channel 140 side. In other words, as shown in Figures 24(a) and 24(b), ink is refilled into the pressure chamber 12 from both the supply channel 130 (common supply channel 18) and the first recovery channel 140 (common recovery channel 19). Specifically, the ink supplied from the first pressure control chamber 122 to the bypass channel 160 is supplied to the second pressure control chamber 152 via the second valve chamber 151 of the second pressure adjustment means 150. Then, a portion of the ink supplied to the second pressure control chamber 152 is supplied to the first recovery channel 140 and supplied to the discharge port 13 via the common recovery channel 19.

[0131] Figure 25 illustrates the ink supply within the ejection module 300. Figure 25(a) shows the flow path configuration near the pressure chamber 12 and is a comparative example different from this embodiment. In Figure 25(a), only one side of the pressure chamber 12 communicates with the flow path 2010. In this configuration, ink is supplied to the pressure chamber 12 only from the flow path 2010, making it a one-sided supply. In the configuration of Figure 25(a), the independent supply port 2020 communicating with the pressure chamber 12 is connected to the common supply flow path 18 or the common recovery flow path 19, or both. When a thermal type ejection element is used as the ejection element 15, ink is ejected from the ejection port 13 due to foaming within the pressure chamber 12. In addition, ink is refilled into the pressure chamber 12 by defoaming in response to this foaming. In such a flow path configuration, the width of the flow path 2010 connected to the pressure chamber 12 is narrowed or the length is increased to increase the rear resistance during foaming. This makes the foaming more symmetrical and improves droplet formation. On the other hand, in the configuration shown in Figure 25(a), when refilling ink into the pressure chamber 12 during defoaming after ejection, the supply efficiency decreases due to increased rear resistance. Therefore, it is generally difficult to improve the refill frequency with the flow path configuration shown in Figure 25(a). In particular, when performing recording operations at high duty cycles, the amount of ink supplied to the ejection port 13 decreases, which may reduce ejection stability.

[0132] On the other hand, Figure 25(b) shows the flow path configuration near the pressure chamber 12 in this embodiment. The supply connection flow path 323, which is the first independent supply port, connects the first liquid flow path 2030 leading to the pressure chamber 12 and the common supply flow path 18. The recovery connection flow path 324, which is the second independent supply port, connects the second liquid flow path 2040 leading to the pressure chamber 12 and the common recovery flow path 19. As described above, in this embodiment, the ink discharged from the discharge port 13 is refilled from the first liquid flow path 2030 and the second liquid flow path 2040. As shown in Figure 25(b), the pressure chamber 12 has a double-sided supply configuration in which both sides communicate with the first liquid flow path 2030 and the second liquid flow path 2040. In such a configuration, as shown in Figure 25(b), even if the width of the flow path leading to the pressure chamber 12 is widened or the length is shortened, the foaming tends to become more symmetrical due to the symmetry of the backward resistance during foaming. Therefore, the formation of ink droplets tends to improve. Furthermore, since the refilling of ink into the pressure chamber 12 during defoaming after ejection does not increase backward resistance, ink supply performance can be improved. Thus, according to this embodiment, ejection stability can be improved even when recording operations are performed at a high duty cycle. In other words, it is possible to achieve both improved droplet formation and improved refill frequency.

[0133] In the embodiments described above, the case using a thermal discharge element was mainly explained, but a piezoelectric discharge element may also be used. However, since it is more difficult to achieve both improved droplet formation and increased refill frequency with the thermal method, the thermal method is preferred in this embodiment.

[0134] <Connection between the main unit and the liquid dispensing head> Figure 26 is a schematic diagram showing the connection between the ink tank 2 and ink supply unit 400 provided in the main body of the liquid ejection device 50 of this embodiment and the liquid ejection head 1. The liquid ejection device 50 of this embodiment is configured to allow only the liquid ejection head 1 to be easily replaced in the event of a malfunction in the liquid ejection head 1. Specifically, a main body-side connecting member 470 and a head-side connecting member 800 are provided to easily connect and disconnect the liquid ejection head 1 from the second supply passage 112 and the third air passage 113 connected to the ink supply unit 400. This makes it possible to easily attach and detach only the liquid ejection head 1 from the liquid ejection device 50.

[0135] As shown in Figure 26, the head-side connecting member 800 is detachably attached to the head housing 53 of the liquid discharge head 1. The head-side connecting member 800 is connected to the ink supply passage (third supply passage 910) in the circulation unit 54 via the filter 110. The head-side connecting member 800 is also connected to the first de-aeration unit 770A and the second de-aeration unit 770B via the de-aeration passage 541 in the circulation unit 54.

[0136] The main unit-side connecting member 470 is provided at the ends of the second supply passage 112 and the third air passage 113. The second supply passage 112 is also referred to as the ink supply tube 450. The third air passage 113 is also referred to as the degassing tube 460. The main unit-side connecting member 470 is connected to the second supply passage 112 (ink supply tube 450) and also to the third air passage 113 (degassing tube 460).

[0137] The main unit-side connecting member 470 is detachably connected to the head-side connecting member 800, which is attached to the head housing 53. With the main unit-side connecting member 470 connected to the head-side connecting member 800, the second supply passage 112 communicates with the ink supply passage (third supply passage 910) in the circulation unit 54 via the filter 110. Also, with the main unit-side connecting member 470 connected to the head-side connecting member 800, the third air passage 113 communicates with the degassing passage 541 in the circulation unit 54. This allows for easy connection and disconnection of the second supply passage 112 (ink supply tube 450) and the third air passage 113 (degassing tube 460) connected to the ink supply unit 400 and the liquid ejection head 1. Therefore, the attachment, detachment, and replacement of the liquid ejection head 1 can be easily performed.

[0138] <Configuration of the bubble removal unit> Figure 27 is a schematic diagram of the foam removal unit 770. Figure 27(a) is a cross-sectional view of the foam removal unit 770. Figure 27(b) is a schematic diagram of the deformation suppression member 720 in the foam removal unit 770. The second foam removal unit 770B has the same configuration as the first foam removal unit 770A. The second foam accumulation chamber 520B has the same configuration as the first foam accumulation chamber 520A. Therefore, the first foam removal unit 770A and the second foam removal unit 770B may be described together as the foam removal unit 770. The first foam accumulation chamber 520A and the second foam accumulation chamber 520B may be described together as the foam accumulation chamber 520. As shown in Figure 27(a), the de-bubble unit 770 (first de-bubble unit 770A and second de-bubble unit 770B) has a foam accumulation chamber 520 (first foam accumulation chamber 520A and second foam accumulation chamber 520B) and a pressure reduction chamber 760. Furthermore, the de-bubble unit 770 has a gas permeable membrane 710, a deformation suppression member 720, a first communication port 751 for connecting the foam accumulation chamber 520 to a liquid flow path or liquid chamber, and a second communication port 761 for connecting the pressure reduction chamber 760 to an ink supply unit 400.

[0139] The bubble removal unit 770 (first bubble removal unit 770A and second bubble removal unit 770B) communicates with the ink supply unit 400 located in the main body of the liquid dispensing device 50, and is depressurized by the operation of the ink supply unit 400. Furthermore, a third check valve 213 is provided between the bubble removal unit 770 and the ink supply unit 400, so that the depressurized state is maintained even when the liquid dispensing device 50 is not operating, thereby enabling the bubble removal operation. The third check valve 213 may be provided at the branched portions of the third air passage 113 between the ink supply unit 400 and the first bubble removal unit 770A and the second bubble removal unit 770B. The third check valve 213 may also be provided at the concentrated portion of the third air passage 113 between the ink supply unit 400 and the first bubble removal unit 770A and the second bubble removal unit 770B.

[0140] As shown in Figure 10(a), the first de-aeration unit 770A is provided vertically above the supply channel 130, and the second de-aeration unit 770B is provided vertically above the first recovery channel 140, but it is not limited to this. For example, one de-aeration unit 770 (first de-aeration unit 770A) may be provided only in the supply channel 130. The de-aeration unit 770 may be provided vertically above the ink tank 2, the first supply channel 111, the second supply channel 112, the third supply channel 910, the filter 110, the pump inlet channel 170, the pump outlet channel 180, the bypass channel 160, the pressure chamber 12, etc. Also, as shown in Figure 10(b), the first foam reservoir chamber 520A may communicate with the side of the supply channel 130, and the first de-aeration unit 770A may be formed extending to the side of the first foam reservoir chamber 520A. The second foam accumulation chamber 520B may communicate with the side of the first recovery channel 140, and the second foam removal unit 770B may be formed extending laterally from the second foam accumulation chamber 520B. Alternatively, the foam accumulation chamber 520 may communicate with the side of a fluid communication section other than the supply channel 130 and the first recovery channel 140, and the foam removal unit 770 may be formed extending laterally from the foam accumulation chamber 520, as long as the configuration allows for the collection of foam and contact with the gas permeable membrane 710. In other words, the foam removal unit 770 may be formed extending horizontally from the foam accumulation chamber 520, rather than vertically above it.

[0141] <Gas permeable membrane> As shown in Figure 27(a), the gas permeable membrane 710 is provided in the housing of the circulation unit 54 that forms the foam reservoir chamber 520, so as to separate the foam reservoir chamber 520 from the depressurization chamber 760. Hereafter, the housing of the circulation unit 54 that forms the foam reservoir chamber 520 will be referred to as the unit housing 540. The gas permeable membrane 710 is bonded to the unit housing 540 by bonding methods such as heat welding, ultrasonic welding, or laser welding. Any bonding method such as heat welding, ultrasonic welding, or laser welding can be used as long as it is sealed so that the liquid (ink) in the foam reservoir chamber 520 does not leak into the depressurization chamber 760. The material of the gas permeable membrane 710 is preferably resin. Specifically, examples of materials for the gas permeable membrane 710 include polypropylene (PP), polymethylpentene (TPX), and polytetrafluoroethylene (PTFE). To improve de-bubbling efficiency, the material of the gas permeable membrane 710 should preferably have high gas permeability. To obtain the required de-bubbling efficiency for the product, a certain level of gas permeability is required for the material of the gas permeable membrane 710. Furthermore, the material of the gas permeable membrane 710 should be easy to bond to the unit housing 540 by heat welding, thus requiring productivity. The material of the gas permeable membrane 710 should also be reliable against tearing and peeling of the gas permeable membrane 710. The material of the gas permeable membrane 710 should also be reliable as a wetted material. Thus, it is desirable to select the material of the gas permeable membrane 710 from the viewpoints of gas permeability, manufacturing method (productivity), and reliability.

[0142] The foam flowing into the foam storage chamber 520 includes initial foam remaining after initial filling (approximately 0.2 cc), tank replacement foam that flows in during normal use (approximately 0.015 cc per month), and permeate foam from gas permeating from the outside (approximately 0.001 cc / day). To process this foam, a defoaming operation is required when the foam permeation rate is 0.01 cc / day or more. As specified in "JIS K7126-1", the amount of gas permeation through the gas permeable membrane 710 can be verified by methods such as the pressure sensor method. The pressure sensor method is a method of measuring gas permeability by keeping one side (low-pressure side) separated by a test piece under vacuum, introducing a test gas to the other side (high-pressure side), and measuring the increase in pressure on the low-pressure side. According to the pressure sensor method, the gas permeability coefficient can be calculated from the gas permeability and the thickness of the test piece. In the pressure sensor method, the amount of gas permeation through the gas permeable membrane can be verified by measuring the gas permeability using the test piece as a gas permeable membrane. In the initial filling of the normal suction described later, ink is filled into the liquid discharge head 1, the bubbles in the bubble reservoir chamber 520 are brought into contact with the entire gas permeable membrane 710, and the pressure of the gas in the depressurization chamber 760 is maintained at a negative pressure of approximately 50 kPa by the ink supply unit 400, and the unit is left at room temperature and atmospheric pressure. In this series of operations, the amount of bubbles in the bubble reservoir chamber 520 can be measured over time using computed tomography (CT) or the like to verify the amount of bubbles (gas) permeating through the gas permeable membrane 710. Since the gas permeable membrane 710 is welded to the unit housing 540 to seal the bubble reservoir chamber 520, the material of the gas permeable membrane 710 should be one that is highly reliable in terms of welding reliability and reliability as a wetted material. In order to achieve a bubble permeation rate of 0.01 cc / day or more, the thickness of the gas permeable membrane 710 should preferably be 0.1 mm or less.

[0143] <Bubble-making room> As shown in Figure 10(a), the first foam reservoir chamber 520A is provided vertically above the supply channel 130 so as to be in fluid communication with the supply channel 130 via the first communication port 751. The second foam reservoir chamber 520B is provided vertically above the first recovery channel 140 so as to be in fluid communication with the first recovery channel 140 via the first communication port 751. As a result, foam mixed in with the ink in the first pressure adjustment means 120, the second pressure adjustment means 150, the supply channel 130, the first recovery channel 140, etc., due to circulation and discharge operations can be collected in the foam reservoir chamber 520 and discharged from the ink by a de-foaming operation. Examples of foam mixed with the ink include upstream foam that enters the channel when the ink tank 2 is replaced, eluted foam that is generated in the channel due to environmental changes, and unexpected foam that is generated in the channel unexpectedly. However, the types of foam discharged by the de-foaming operation are not limited to these. If the amount of foam is such that it can be collected in the foam collection chamber 520 and a sufficient foam removal speed can be obtained, the foam mixed in the ink can be discharged to the outside of the liquid ejection head 1.

[0144] Examples of materials for the unit housing 540 that forms the foam reservoir chamber 520 include polypropylene (PP) and polyethylene (PE). From the viewpoint of reliability of welding of the gas permeable membrane 710 and ease of handling, it is desirable that the material of the unit housing 540 be polypropylene.

[0145] <Decompression Chamber> As shown in Figure 27(a), the depressurization chamber 760 has an opening in which the gas permeable membrane 710 is placed, an opening opposite this opening for welding the gas permeable membrane 710, and a second communication port 761. The depressurization chamber 760 is formed by being surrounded by the unit housing 540, the gas permeable membrane 710, and the cover member 730. The second communication port 761 is formed through the side of the unit housing 540 and connects the depressurization chamber 760 to the degassing channel 541 (see Figure 26). The opening for welding the gas permeable membrane 710 is sealed by bonding a separate cover member 730 to the unit housing 540. Methods for bonding the cover member 730 include heat welding, ultrasonic welding, and laser welding. Examples of materials for the cover member 730 include polypropylene (PP) and polyethylene (PE). From the standpoint of reliability of welding the cover member 730 and ease of handling, it is desirable that the material of the cover member 730 be the same as the material of the unit housing 540 that forms the foam reservoir chamber 520.

[0146] <Deformation-suppressing member> As shown in Figure 27(b), the deformation suppressing member 720 is formed using a mesh filter made of stainless steel (SUS) that is configured in a mesh-like structure. In Figure 27(b), a dot pattern is added to the gas permeable membrane 710 for clarity of the deformation suppressing member 720. The dot pattern on the gas permeable membrane 710 in Figure 27(b) does not represent a cross-section of the gas permeable membrane 710. When the pressure reduction chamber 760 is reduced by the ink supply unit 400, the gas permeable membrane 710 attempts to deform toward the pressure reduction chamber 760. The deformation suppressing member 720 contacts the gas permeable membrane 710 that attempts to deform toward the pressure reduction chamber 760, thereby suppressing the deformation of the gas permeable membrane 710 and preventing it from tearing or peeling. The deformation suppressing member 720 is provided at the tip of the cover member 730. For example, the deformation suppressing member 720 is bonded to the tip of the cover member 730 by bonding methods such as heat welding, ultrasonic welding, or laser welding. The deformation suppressing member 720 is positioned to cover the gas permeable membrane 710, either at a position where it contacts the gas permeable membrane 710 or at a position a certain distance away from the gas permeable membrane 710, while the cover member 730 is bonded to the unit housing 540. In addition to stainless steel (SUS), nickel (Ni) and other materials can be used as the material for the deformation suppressing member 720. It is desirable that the material for the deformation suppressing member 720 be one that offers high reliability in welding and is easy to handle.

[0147] The foam retention chamber 520 is formed by the unit housing 540, but is not limited to this. Figure 28 shows a modified example of the foam removal unit 770. Figure 28(a) shows an example in which a side film 780 is used in part of the foam retention chamber 520. Figure 28(b) shows an example in which a side film 780 is used in part of the reduced pressure chamber 760. As shown in Figure 28(a), part of the foam retention chamber 520 may be formed by a side film 780 welded to the unit housing 540. In order to suppress the increase of foam in the foam retention chamber 520, liquid flow path, liquid chamber, etc., it is desirable that the material of the side film 780 be a resin with high gas barrier properties such as polyethylene terephthalate (PET) or nylon (Ny). The volume of the foam retention chamber 520 should be a volume that can collect the amount of foam determined by the foam design of the product.

[0148] As shown in Figure 28(b), a portion of the depressurization chamber 760 may be formed by a side film 780 welded to the unit housing 540. To reduce the decrease in the degree of depressurization of the depressurization chamber 760, it is desirable that the material of the side film 780 be a resin with high gas barrier properties, such as polyethylene terephthalate (PET) or nylon (Ny). In addition, the gas permeable membrane 710 may be placed between the unit housing 540 of the foam reservoir chamber 520 or between the unit housing 540 of the depressurization chamber 760, with an elastic member in between. In this case, it is not necessary to weld the gas permeable membrane 710 to the foam reservoir chamber 520. For this reason, the opening of the depressurization chamber 760 and the cover member 730 that seals the opening are not necessary, and the depressurization chamber 760 may be formed by the unit housing 540 or the side film 780. The volume of the depressurization chamber 760 needs to be a volume that can collect the amount of foam determined by the foam design of the product.

[0149] Figure 29 is a cross-sectional view showing a first modified example of the deformation suppression member 720. The deformation suppression member 720 is not limited to a mesh filter, but may also be formed using, for example, a nonwoven fabric member with densely packed fibers as shown in Figure 29. In this case, in order for the nonwoven fabric member to not be sucked into the ink supply unit 400 when the pressure reduction chamber 760 is reduced, it is necessary to use a nonwoven fabric member with a hardness above a certain value, or to reduce the pressure of the pressure reduction chamber 760 to below a certain value. The nonwoven fabric member also has a certain degree of elasticity. For this reason, by designing the size of the deformation suppression member 720 to be approximately the same as the volume of the pressure reduction chamber 760, it is possible to place the deformation suppression member 720 inside the pressure reduction chamber 760 without extending the cover member 730 into the pressure reduction chamber 760.

[0150] Figure 30 is a schematic diagram showing another modified example of the deformation suppressing member 720. Figure 30(a) is a cross-sectional view showing a second modified example of the deformation suppressing member 720. Figure 30(b) is a schematic diagram showing a second modified example of the deformation suppressing member 720. Figure 30(c) is a schematic diagram showing a third modified example of the deformation suppressing member 720. As shown in Figure 30(a), the deformation suppressing member 720 may be a rib-shaped member integrally formed with the cover member 730. The rib shape of the deformation suppressing member 720 may be a linear rib shape as shown in Figure 30(b). The rib shape of the deformation suppressing member 720 is not limited to a linear rib shape, but may also be a grid-like rib shape as shown in Figure 30(c). In this case, in order to suppress the maximum deformation amount of the gas permeable membrane 710, it is desirable that the rib shape of the deformation suppressing member 720 be a rib shape that contacts the vicinity of the center of the gas permeable membrane 710. In order to suppress the maximum deformation amount of the gas permeable membrane 710, it is desirable to increase the number of ribs constituting the deformation suppressing member 720. Furthermore, if the deformation suppressing member 720 is provided at the tip of the cover member 730, and the deformation suppressing member 720 comes into contact with a part of the gas permeable membrane 710, the effective area for permeating bubbles in the gas permeable membrane 710 will be reduced, requiring adjustment of the configuration of other components and the bubble design of the product. Also, if the depressurization chamber 760 does not require a cover member 730, the deformation suppressing member 720 may be installed in the unit housing 540 that forms the bubble reservoir chamber 520, or in the unit housing 540 that forms the depressurization chamber 760.

[0151] <The principle of removing bubbles> During the de-aeration operation, the depressurization chamber 760 is reduced in pressure, causing the bubbles to permeate the gas permeable membrane 710 due to the pressure difference between the pressure of the bubbles in the bubble reservoir chamber 520 and the pressure of the gas in the depressurization chamber 760. The amount of permeation during the de-aeration operation is expressed by the following equation (5). Q = P × p × S × t / L ... (5) Q: Gas permeability P: Transmittance coefficient p: Degree of pressure reduction (gauge pressure) S: Foam contact area t: time L: Thickness of gas permeable membrane 710

[0152] The gas permeation rate, represented by Q, is the amount of gas permeating through the bubbles during the de-bubbling process. The permeation coefficient, represented by P, is a value determined by the material properties of the gas permeable membrane 710 and represents the basic speed of the de-bubbling process. The degree of depressurization, represented by p, is the degree of depressurization (gauge pressure) of the depressurization chamber 760. The bubble contact area, represented by S, is the area in contact between the bubbles and the gas permeable membrane 710. The value represented by L is the thickness of the gas permeable membrane 710.

[0153] <Initial filling> Figure 31 is a schematic diagram showing the operation of the initial filling and de-bubbling unit. Figure 31(a) is a schematic diagram showing the ink flow and remaining bubbles when the liquid discharge head 1 is initially filled with ink. Initial filling is performed by closely pressing the cap member against the discharge port surface where the discharge port of the liquid discharge head 1 is formed, and forcibly sucking the ink from the discharge port. At this time, the negative pressure from the negative pressure source connected to the cap member is applied to the discharge port, forcibly sucking the ink from the discharge port. When performing initial filling, if there are areas where the ink flow stagnates due to variations in the molding or assembly of the parts, a small amount of bubbles may adhere to the wall surface, etc. There are normal suction operations and choke suction, and the filling state of the de-bubbling unit changes depending on the method of suction operation. In normal suction, suction is performed without any special operation, so in the ink flow path shown in Figure 31(a), gas-liquid exchange is performed by supplying ink from the upstream side of the ink flow path, and ink is filled in most of the ink flow path. However, since the foam reservoir chambers 520 (first foam reservoir chamber 520A and second foam reservoir chamber 520B) do not become part of the ink flow path, gas-liquid exchange does not occur, and foam remains in most of the foam reservoir chambers 520. In choke suction, the flow path upstream of the ink flow path is closed with a valve or the like, and the entire liquid discharge head 1 is sufficiently depressurized by the suction operation. Then, the upstream valve is opened, allowing ink to flow into the liquid discharge head 1 from the upstream side of the ink flow path. As a result, in the ink flow path shown in Figure 31(a), ink fills most of the ink flow path, similar to normal suction, and in the foam reservoir chambers 520, the amount of ink filled increases as the degree of depressurization due to the suction operation increases. For example, when choke suction is performed at -50kPa (gauge pressure), ink fills about half of the foam reservoir chamber 520.

[0154] <Operation of the bubble removal unit> Figure 31(b) is a schematic diagram showing the state inside the circulation unit after initial filling. Figure 31(c) is a schematic diagram showing the state of remaining foam after initial filling. After initial filling, foam accumulates in the foam reservoir chamber 520 (first foam reservoir chamber 520A and second foam reservoir chamber 520B), so the pressure reduction chamber 760 is reduced to remove the foam. Since gas constantly permeates the unit housing or side film from the outside into the foam reservoir chamber 520, it is necessary to perform a foam removal operation in accordance with the foam design of the product. The pressure reduction chamber 760 is reduced in pressure by the ink supply section 400 of the main body of the liquid discharge device 50 through the second communication port 761. The higher the degree of pressure reduction, the greater the amount of foam permeation, so it is desirable to set the degree of pressure reduction to at least 10 kPa in order to obtain a sufficient amount of foam permeation to handle the foam generated during normal use. Furthermore, if the degree of pressure reduction is excessively high, the gas permeable membrane 710 may deform significantly towards the pressure reduction chamber 760, potentially causing peeling at the welded portion of the gas permeable membrane 710. Therefore, it is desirable to keep the degree of pressure reduction at around 70 kPa or less. Also, since the ink supply unit 400 for reducing the pressure in the pressure reduction chamber 760 utilizes the pressurizing means in the upstream flow path (for example, the aforementioned one-way pump 404), the degree of pressure reduction in the pressure reduction chamber 760 is affected by the operation or output of that pressurizing means. As can be seen from the above explanation, it is desirable that the degree of pressure reduction appropriate for the operation of the ink supply unit 400, while ensuring sufficient bubble permeation, high reliability of the gas permeable membrane 710, is around 50 kPa. The pressure reduction state of the pressure reduction chamber 760 can be maintained by keeping the liquid discharge device 50 running continuously. When the main body of the liquid discharge device 50 is not in operation, the third check valve 213 provided between the second communication port 761 (see Figure 27(a)) and the ink supply unit 400 is used. The third check valve 213 seals the pressure reduction chamber 760 when it reaches a certain degree of pressure reduction. This allows the de-aeration operation to continue even when the main body of the liquid dispensing device 50 is not in operation, by maintaining the pressure reduction state of the pressure reduction chamber 760, making it possible to deal with bubbles that increase due to, for example, prolonged storage. As shown in Figure 31(a), after initial filling, the ink supply unit 400 reduces the pressure in the pressure reduction chamber 760, and then the third check valve 213 maintains the pressure reduction state, allowing bubbles in the bubble accumulation chamber 520 to pass through and be discharged from the ink.When the dispensing operation is performed, ink flows in from upstream, and at the same time, any bubbles that were present upstream are also carried away. In addition, any unintended bubbles that remain in stagnant areas of the ink flow during initial filling are also carried away through the flow path by the dispensing and circulation operations. As shown in Figure 31(c), the buoyancy of the bubbles allows them to be collected through the first communication port 751 of the bubble removal unit 770 (see Figure 27(a)), and by performing the bubble removal operation with the pressure reduction chamber 760 in a reduced pressure state, the bubbles can be discharged from the ink. By repeating this bubble removal operation, bubbles that are newly generated during normal use will not flow into the pressure chamber 12, thus reducing the possibility of dispensing failures. When the pressure reduction state of the pressure reduction chamber 760 is maintained by the third check valve 213, performing the bubble removal operation causes bubbles to permeate into the pressure reduction chamber 760, reducing the degree of pressure reduction in the pressure reduction chamber 760, thus reducing the bubble removal efficiency. The amount of reduction in the degree of pressure reduction is expressed by the following equation (6). (p² × Q + p¹ × Q¹) / v ···(6) p1: Atmospheric pressure (absolute pressure) p2: Internal pressure of the foam (absolute pressure) v: Volume of decompression chamber 760 Q1: Amount of transmission from the outside

[0155] The internal pressure of the bubble, represented by p2, is the same as the pressure of the ink. The larger the volume of the depressurization chamber 760, represented by v, the smaller the decrease in the degree of depressurization due to the de-bubbling operation, and the more effectively the de-bubbling efficiency can be suppressed. The amount of permeation from the outside, represented by Q1, is the amount of gas that permeates from the outside into the depressurization chamber 760, and is determined by the material of the unit housing that forms the depressurization chamber 760, the surface area of ​​the part of the unit housing that is in contact with the outside air, and the thickness of the unit housing.

[0156] If the degree of depressurization in the depressurization chamber 760 decreases, the third check valve 213 and the ink supply unit 400 are activated to increase the degree of depressurization in the depressurization chamber 760, thereby maintaining the de-bubbling efficiency. The operation to increase the degree of depressurization (for example, the de-bubbling depressurization operation described above) may be performed periodically using a timer. The operation to increase the degree of depressurization may also be triggered by detecting the degree of depressurization in the depressurization chamber 760 with a sensor and a predetermined decrease in the degree of depressurization. When the depressurization chamber 760 becomes depressurized and the gas permeable membrane 710 deforms toward the depressurization chamber 760, the deformation suppression member 720 comes into contact with the gas permeable membrane 710 from the depressurization chamber 760 side. The deformation suppression member 720 suppresses the deformation of the gas permeable membrane 710 by pressing it in a direction that suppresses the deformation of the gas permeable membrane 710. By suppressing the deformation of the gas permeable membrane 710, the load on the welded portion of the gas permeable membrane 710 is reduced, thereby reducing the possibility of the gas permeable membrane 710 peeling off.

[0157] In this embodiment, the operation of the bubble removal unit was described using a configuration in which the bubble removal unit 770 (first bubble removal unit 770A and second bubble removal unit 770B) has a bubble accumulation chamber 520 (first bubble accumulation chamber 520A and second bubble accumulation chamber 520B) as an example, but the configuration is not limited to this. If the space between the pressure chamber 12 and the depressurization chamber 760 is used as a liquid storage chamber for storing liquid (ink) to be supplied to the pressure chamber 12, a configuration in which bubbles accumulate in a part of the liquid storage chamber is also possible. In this case, a gas permeable membrane is formed at a position in contact with the liquid storage chamber, and the depressurization chamber is adjacent to the liquid storage chamber via the gas permeable membrane.

[0158] Furthermore, the configuration of the circulation path in this embodiment is not limited to the configuration described above. Therefore, as other configurations of the circulation path, the first and second configuration examples of the ink path, and various modifications of the circulation path will be described.

[0159] <First example of ink path configuration> Figure 32 is a schematic diagram showing a first configuration example of the ink path. The first configuration example of the ink path shows an example in which the second pressure adjustment means 150, the second foam reservoir chamber 520B, the circulation pump 500, the bypass flow path 160, and the first recovery flow path 140 are not arranged. In the first configuration example of the ink path, ink is not circulated, and the ink supplied from the second supply path 112 flows in the order of the first pressure adjustment means 120, the supply flow path 130, and the pressure chamber 12, and is discharged from the discharge port 13. The first pressure control chamber 122, the supply flow path 130, and the pressure chamber 12 are pressure-controlled by the first pressure adjustment means 120, thus achieving stable ink discharge.

[0160] The first foam reservoir chamber 520A is located vertically above the supply channel 130 so as to be in fluid communication with the supply channel 130, and the first foam removal unit 770A is formed extending vertically above the first foam reservoir chamber 520A. This allows foam mixed into the ink in the first pressure adjustment means 120 or the supply channel 130, etc., through circulation and discharge operations to be collected in the first foam reservoir chamber 520A and discharged from the ink by a foam removal operation. The foam mixed into the ink includes the aforementioned upstream foam, elution foam, and unintended foam, but is not limited to these. It is possible to discharge from the ink any amount of foam that can be collected in the foam reservoir chamber 520 and that is sufficient to achieve a sufficient foam removal speed. Therefore, the possibility of foam entering the discharge port 13 can be greatly reduced.

[0161] The first bubble removal unit 770A communicates with the ink supply unit 400 of the main body of the liquid dispensing device 50, and is depressurized by the operation of the ink supply unit 400. Furthermore, a third check valve 213 is provided between the bubble removal unit 770 and the ink supply unit 400, so that the depressurized state is maintained even when the main body of the liquid dispensing device 50 is not constantly operating, thereby enabling the bubble removal operation. The third check valve 213 may also be provided in the third air passage 113 between the first bubble removal unit 770A and the ink supply unit 400.

[0162] There may be two or more foam retention chambers 520 and foam removal units 770. Furthermore, the foam retention chambers 520 and foam removal units 770 do not necessarily have to be located in the supply channel 130. For example, the foam retention chambers 520 and foam removal units 770 may be located vertically above the ink tank 2, the first supply channel 111, the second supply channel 112, the third supply channel 910, the filter 110, the pressure chamber 12, etc. Also, the foam retention chambers 520 and foam removal units 770 do not necessarily have to be located vertically above the fluid communication section such as the supply channel 130. As long as the configuration allows for the collection of bubbles and contact with the gas permeable membrane, the foam retention chambers 520 may communicate with the side surface of the fluid communication section, and the foam removal units 770 may extend laterally from the foam retention chambers 520. This also applies when foam reservoirs 520 and foam removal units 770 are provided in multiple parts of the fluid communication section other than the supply channel 130 and the first recovery channel 140.

[0163] <First variation of the circulation path> Figures 33 and 35 schematically show the first modified example of the circulation path. Figure 33 shows the circulation path when circulation is performed without discharge. Figure 35 shows the circulation path when high duty cycle recording is performed. Figure 34 schematically shows the vicinity of the heated circulation pump 904. Figures 34(a), 34(b), 34(c), and 34(d) show an overview of the fluid delivery by the heated circulation pump 904.

[0164] The first modified example of the circulation path shows an example in which the second pressure adjusting means 150, the second foam reservoir chamber 520B, the circulation pump 500, the bypass passage 160, and the first recovery passage 140 are not provided. The first modified example of the circulation path shows an example in which a heated circulation pump 904 provided between the supply passage 130 and the pressure chamber 12 and a second recovery passage 905 connecting the pressure chamber 12 and the supply passage 130 are provided instead of the circulation pump 500, etc. In the first modified example of the circulation path, during circulation as shown in Figure 33, the heated circulation pump 904 circulates the ink within the discharge module 300. Also, during discharge operation as shown in Figure 35, the ink supplied from the second supply passage 112 flows in the order of the first pressure adjusting means 120, the supply passage 130 or the second recovery passage 905, and the pressure chamber 12, and is discharged from the discharge port 13. Furthermore, when recording with a high duty cycle, the ink in the second recovery channel 905 flows in the opposite direction to that during circulation, so ink is supplied to the pressure chamber 12 and the discharge port 13 from both the supply channel 130 and the second recovery channel 905. The first pressure control chamber 122, the supply channel 130, and the pressure chamber 12 are pressure-controlled by the first pressure adjustment means 120, thus ensuring stable ink discharge.

[0165] The first foam reservoir chamber 520A is positioned vertically above the supply channel 130 so as to be in fluid communication with the supply channel 130, and the first foam removal unit 770A is formed extending vertically above the first foam reservoir chamber 520A. This allows foam mixed in with the ink in the first pressure adjustment means 120, supply channel 130, second recovery channel 905, etc., to be collected in the foam reservoir chamber 520 by circulation and discharge operations, and discharged from the ink by foam removal operations. The foam mixed in with the ink includes the aforementioned upstream foam, elution foam, and unintended foam, but is not limited to these. It is possible to discharge from the ink any amount of foam that can be collected in the foam reservoir chamber 520 and that is sufficient to achieve a sufficient foam removal speed. Therefore, the possibility of foam entering the discharge port 13 can be greatly reduced.

[0166] The first bubble removal unit 770A communicates with the ink supply unit 400 of the main body of the liquid dispensing device 50, and is depressurized by the operation of the ink supply unit 400. Furthermore, a third check valve 213 is provided between the bubble removal unit 770 and the ink supply unit 400, so that the depressurized state is maintained even when the main body of the liquid dispensing device 50 is not constantly operating, thereby enabling the bubble removal operation. The third check valve 213 may also be provided in the third air passage 113 between the first bubble removal unit 770A and the ink supply unit 400.

[0167] There may be two or more foam retention chambers 520 and foam removal units 770. Furthermore, the foam retention chambers 520 and foam removal units 770 do not necessarily have to be located in the supply channel 130. For example, the foam retention chambers 520 and foam removal units 770 may be located vertically above the ink tank 2, the first supply channel 111, the second supply channel 112, the third supply channel 910, the filter 110, the pressure chamber 12, the second recovery channel 905, etc. Also, the foam retention chambers 520 and foam removal units 770 do not necessarily have to be located vertically above the fluid communication section such as the supply channel 130. As long as the configuration allows for the collection of foam and contact with the gas permeable membrane, the foam retention chambers 520 may communicate with the side surface of the fluid communication section, and the foam removal units 770 may extend laterally from the foam retention chambers 520. This also applies when foam reservoirs 520 and foam removal units 770 are provided in multiple parts of the fluid communication section other than the supply channel 130 and the first recovery channel 140.

[0168] The heated circulation pump 904 is composed of a heater element capable of heating the ink, and by heating the ink, it generates bubbles from the heater element to transport the ink. First, as shown in Figure 34(a), the ink is rapidly heated by the heater element of the heated circulation pump 904, causing bubbles to be generated and expand due to film boiling. At this time, the amount of bubble expansion differs between the upstream and downstream sides of the ink. Next, as shown in Figure 34(b), the heating is stopped when the bubbles have expanded to a certain value. Next, as shown in Figure 34(c), the bubbles contract due to the cessation of heating. At this time, the amount of bubble contraction differs between the upstream and downstream sides of the ink. Finally, as shown in Figure 34(d), the bubbles completely contract and collapse, causing an ink flow to occur from the upstream side to the downstream side. The processes shown in Figures 34(a), 34(b), 34(c), and 34(d) are repeated, resulting in a steady flow of ink from the supply channel 130 through the pressure chamber 12 to the second recovery channel 905. Furthermore, the heated circulation pump 904 does not need to be located between the supply channel 130 and the pressure chamber 12, but may be located between the pressure chamber 12 and the second recovery channel 905.

[0169] <Second variation of the circulation path> Figures 36 and 37 schematically illustrate a second modified example of the circulation path. Figure 36 shows the circulation path when circulation is performed without discharge. Figure 37 shows the circulation path when recording is performed at a high duty cycle. The second modified example of the circulation path shows an example in which the second pressure adjustment means 150 is not provided and the bypass flow path 160 and the first recovery flow path 140 are directly connected.

[0170] In the second modified example of the circulation path, the flow resistance of the ink flow path from the bypass flow path 160 to the first recovery flow path 140 is denoted as R1, and the flow resistance of the ink flow path from the supply flow path 130 to the first recovery flow path 140 via the discharge module 300 is denoted as R2. Since the flow rate of ink flowing through each flow path is inversely proportional to the flow resistance, the ratio of the flow rate of ink in the flow path via the bypass flow path 160 to the flow rate of ink in the flow path via the discharge module 300 is R2 to R1. In accordance with this relationship, the flow resistance of each flow path is set so that the circulation amount is such that the viscosity of the ink near the discharge port 13 in the discharge module 300 is suppressed. That is, the flow resistance of each flow path is set so that the flow velocity of the ink in the pressure chamber 12 is greater than or equal to a predetermined flow velocity. The flow resistance R1 of the flow path via the bypass flow path 160 is controlled by changing the cross-sectional area or length of the flow path, or by providing a throttling in the flow path.

[0171] In the second modified example of the circulation path, when recording is performed with a high duty cycle, the pressure chamber 12 is supplied from both sides, as shown in Figure 37. That is, ink supplied from the first pressure control chamber 122 to the supply channel 130 is supplied to the discharge port 13 via the common supply channel 18 of the discharge module 300. On the other hand, a portion of the ink supplied from the first pressure control chamber 122 to the bypass channel 160 is supplied to the first pressure control chamber 122 via the circulation pump 500 and the pump outlet channel 180. In addition, a portion of the ink supplied to the bypass channel 160 is supplied to the first recovery channel 140 and supplied to the discharge port 13 via the common recovery channel 19 of the discharge module 300. Therefore, the ink discharged from the discharge port 13 is supplied from either the supply channel 130 or the first recovery channel 140.

[0172] The first foam accumulation chamber 520A is located vertically above the supply channel 130 so as to be in fluid communication with the supply channel 130, and the first foam removal unit 770A extends vertically above the first foam accumulation chamber 520A. The second foam accumulation chamber 520B is located vertically above the first recovery channel 140 so as to be in fluid communication with the first recovery channel 140, and the second foam removal unit 770B extends vertically above the second foam accumulation chamber 520B. As a result, foam mixed in with the ink in the first pressure adjustment means 120, supply channel 130, first recovery channel 140, etc., can be collected in the foam accumulation chamber 520 by circulation and discharge operations, and discharged from the ink by foam removal operations. The bubbles that can get mixed into the ink include the aforementioned upstream bubbles, eluting bubbles, and unintended bubbles, but are not limited to these. It is possible to discharge from the ink an amount of bubbles that can be collected in the bubble reservoir chamber 520 and that is sufficient to achieve a sufficient de-bubbling speed. This makes it very difficult for bubbles to enter the discharge port 13.

[0173] The first bubble removal unit 770A and the second bubble removal unit 770B are in communication with the ink supply unit 400 of the main body of the liquid dispensing device 50, and are depressurized by the operation of the ink supply unit 400. Furthermore, a third check valve 213 is provided between the bubble removal unit 770 and the ink supply unit 400, so that the depressurized state is maintained even when the main body of the liquid dispensing device 50 is not constantly operating, thereby enabling the bubble removal operation. The third check valve 213 may be provided at the branched portions of the third air passage 113 between the ink supply unit 400 and the first bubble removal unit 770A and the second bubble removal unit 770B. The third check valve 213 may be provided at the concentrated portion of the third air passage 113 between the ink supply unit 400 and the first bubble removal unit 770A and the second bubble removal unit 770B.

[0174] The foam accumulation chamber 520 and the foam removal unit 770 do not need to be provided in both the supply channel 130 and the first recovery channel 140; they may be provided only in the supply channel 130 or only in the first recovery channel 140. Furthermore, three or more foam accumulation chambers 520 and foam removal units 770 may be provided. The foam accumulation chamber 520 and the foam removal unit 770 do not need to be provided in both the supply channel 130 and the first recovery channel 140. For example, the foam accumulation chamber 520 and the foam removal unit 770 may be provided vertically above the ink tank 2, the first supply channel 111, the second supply channel 112, the third supply channel 910, etc. The foam accumulation chamber 520 and the foam removal unit 770 may also be provided vertically above the filter 110, the pump outlet channel 180, the bypass channel 160, the pressure chamber 12, etc. Furthermore, the foam accumulation chamber 520 and the foam removal unit 770 do not necessarily have to be located vertically above the fluid communication section such as the supply channel 130. As long as the configuration allows for the collection of foam and its contact with the gas permeable membrane, the foam accumulation chamber 520 may communicate with the side of the fluid communication section, and the foam removal unit 770 may be formed extending laterally from the foam accumulation chamber 520. This is also true when the foam accumulation chamber 520 and the foam removal unit 770 are provided in multiple parts of the fluid communication section other than the supply channel 130 and the first recovery channel 140.

[0175] <Third variation of the circulation path> Figures 38 and 39 schematically show a third modified example of the circulation path. Figure 38 shows the circulation path when circulation is performed without discharge. Figure 39 shows the circulation path when recording is performed with a high duty cycle. The third modified example of the circulation path shows an example in which the second pressure adjustment means 150 is not provided, the bypass flow path 160 and the first recovery flow path 140 are directly connected, and the relief valve 2301 is provided in the bypass flow path 160.

[0176] The relief valve 2301 is configured such that when the ink pressure downstream of the relief valve 2301 falls below a certain value, ink flows in from the upstream side to the downstream side of the relief valve 2301. In other words, the relief valve 2301 is configured to open when the ink pressure on the recovery channel side falls below a certain value compared to the supply channel side. The ink flow in the third modified example of the circulation path is basically the same as when the second pressure adjustment means 150 is arranged, as shown in Figures 38 and 39. The amount of circulation within the discharge module 300 is determined by the pressure difference between the control pressure of the first pressure control chamber 122 and the control pressure of the relief valve 2301. The control pressure of the relief valve 2301 is set to a circulation amount that can suppress the thickening of the ink near the discharge port 13 within the discharge module 300.

[0177] In the third modified example of the circulation path, when recording is performed at a high duty cycle, the pressure chamber 12 is supplied from both sides, as shown in Figure 39. That is, ink supplied from the first pressure control chamber 122 to the supply channel 130 is supplied to the discharge port 13 via the common supply channel 18 of the discharge module 300. On the other hand, a portion of the ink supplied from the first pressure control chamber 122 to the bypass channel 160 passes through the relief valve 2301 and is supplied to the first pressure control chamber 122 via the circulation pump 500 and the pump outlet channel 180. In addition, a portion of the ink supplied to the bypass channel 160 passes through the relief valve 2301 and is supplied to the first recovery channel 140, and is supplied to the discharge port 13 via the common recovery channel 19 of the discharge module 300. Therefore, the ink discharged from the discharge port 13 is supplied from either the supply channel 130 or the first recovery channel 140.

[0178] The first foam accumulation chamber 520A is located vertically above the supply channel 130 so as to be in fluid communication with the supply channel 130, and the first foam removal unit 770A extends vertically above the first foam accumulation chamber 520A. The second foam accumulation chamber 520B is located vertically above the first recovery channel 140 so as to be in fluid communication with the first recovery channel 140, and the second foam removal unit 770B extends vertically above the second foam accumulation chamber 520B. As a result, foam mixed in with the ink in the first pressure adjustment means 120, supply channel 130, first recovery channel 140, etc., can be collected in the foam accumulation chamber 520 by circulation and discharge operations, and discharged from the ink by foam removal operations. The bubbles that can get mixed into the ink include the aforementioned upstream bubbles, eluting bubbles, and unintended bubbles, but are not limited to these. It is possible to discharge from the ink an amount of bubbles that can be collected in the bubble reservoir chamber 520 and that is sufficient to achieve a sufficient de-bubbling speed. This makes it very difficult for bubbles to enter the discharge port 13.

[0179] The first bubble removal unit 770A and the second bubble removal unit 770B are in communication with the ink supply unit 400 of the main body of the liquid dispensing device 50, and are depressurized by the operation of the ink supply unit 400. Furthermore, a third check valve 213 is provided between the bubble removal unit 770 and the ink supply unit 400, so that the depressurized state is maintained even when the main body of the liquid dispensing device 50 is not constantly operating, thereby enabling the bubble removal operation. The third check valve 213 may be provided at the branched portions of the third air passage 113 between the ink supply unit 400 and the first bubble removal unit 770A and the second bubble removal unit 770B. The third check valve 213 may be provided at the concentrated portion of the third air passage 113 between the ink supply unit 400 and the first bubble removal unit 770A and the second bubble removal unit 770B.

[0180] The foam accumulation chamber 520 and the foam removal unit 770 do not need to be provided in both the supply channel 130 and the first recovery channel 140; they may be provided only in the supply channel 130 or only in the first recovery channel 140. Furthermore, three or more foam accumulation chambers 520 and foam removal units 770 may be provided. The foam accumulation chamber 520 and the foam removal unit 770 do not need to be provided in both the supply channel 130 and the first recovery channel 140. For example, the foam accumulation chamber 520 and the foam removal unit 770 may be provided vertically above the ink tank 2, the first supply channel 111, the second supply channel 112, the third supply channel 910, etc. The foam accumulation chamber 520 and the foam removal unit 770 may also be provided vertically above the filter 110, the pump outlet channel 180, the bypass channel 160, the pressure chamber 12, etc. Furthermore, the foam accumulation chamber 520 and the foam removal unit 770 do not necessarily have to be located vertically above the fluid communication section such as the supply channel 130. As long as the configuration allows for the collection of foam and its contact with the gas permeable membrane, the foam accumulation chamber 520 may communicate with the side of the fluid communication section, and the foam removal unit 770 may be formed extending laterally from the foam accumulation chamber 520. This is also true when the foam accumulation chamber 520 and the foam removal unit 770 are provided in multiple parts of the fluid communication section other than the supply channel 130 and the first recovery channel 140.

[0181] <Second example of ink path configuration> Figure 40 is a schematic diagram showing a second configuration example of the ink path. The second configuration example of the ink path shows an example in which the first pressure adjustment means 120 and the second pressure adjustment means 150, the second foam reservoir chamber 520B, the circulation pump 500, the bypass passage 160, and the first recovery passage 140 are not arranged. Furthermore, the second configuration example of the ink path shows an example in which a third pressure adjustment means 902 communicating with the second supply passage 112 is arranged instead of the first pressure adjustment means 120 and the second pressure adjustment means 150, etc. In the second configuration example of the ink path, ink is not circulated, and the ink supplied from the second supply passage 112 flows in the order of the supply passage 130 and the pressure chamber 12, and is discharged from the discharge port 13. Since the second supply passage 112, the third supply passage 910, the supply passage 130, and the pressure chamber 12 are pressure-controlled by the third pressure adjustment means 902, stable ink discharge is achieved.

[0182] The third pressure adjustment means 902 is located outside the liquid ejection head 1 and communicates with the third supply passage 910 of the liquid ejection head 1 via the second supply passage 112. The third pressure adjustment means 902 may be a head-based system that utilizes the difference in head, for example, but any method is applicable. This modification is applicable to both ink cartridge systems and ink supply systems such as the CISS system.

[0183] The first foam reservoir chamber 520A is located vertically above the supply channel 130 so as to be in fluid communication with the supply channel 130, and the first foam removal unit 770A is formed extending vertically above the first foam reservoir chamber 520A. This allows foam mixed into the ink in the supply channel 130, etc., through circulation and discharge operations to be collected in the foam reservoir chamber 520A and discharged from the ink through foam removal operations. The foam mixed into the ink includes the aforementioned upstream foam, elution foam, and unintended foam, but is not limited to these. It is possible to discharge from the ink any amount of foam that can be collected in the foam reservoir chamber 520 and that is sufficient to achieve a sufficient foam removal speed. Therefore, the possibility of foam entering the discharge port 13 can be greatly reduced.

[0184] The first bubble removal unit 770A communicates with the ink supply unit 400 of the main body of the liquid dispensing device 50, and is depressurized by the operation of the ink supply unit 400. Furthermore, a third check valve 213 is provided between the bubble removal unit 770 and the ink supply unit 400, so that the depressurized state is maintained even when the main body of the liquid dispensing device 50 is not constantly operating, thereby enabling the bubble removal operation. The third check valve 213 may also be provided in the third air passage 113 between the first bubble removal unit 770A and the ink supply unit 400.

[0185] There may be two or more foam retention chambers 520 and foam removal units 770. Furthermore, the foam retention chambers 520 and foam removal units 770 do not necessarily have to be located in the supply channel 130. For example, the foam retention chambers 520 and foam removal units 770 may be located vertically above the ink tank 2, the first supply channel 111, the second supply channel 112, the third supply channel 910, the filter 110, the pressure chamber 12, etc. Also, the foam retention chambers 520 and foam removal units 770 do not necessarily have to be located vertically above the fluid communication section such as the supply channel 130. As long as the configuration allows for the collection of bubbles and contact with the gas permeable membrane, the foam retention chambers 520 may communicate with the side surface of the fluid communication section, and the foam removal units 770 may extend laterally from the foam retention chambers 520. This also applies when foam reservoirs 520 and foam removal units 770 are provided in multiple parts of the fluid communication section other than the supply channel 130 and the first recovery channel 140.

[0186] <Fourth variation of the circulation path> Figures 41 and 42 schematically show a fourth modified example of the circulation path. Figure 41 shows the circulation path when circulation is performed without discharge. Figure 42 shows the circulation path when high duty cycle recording is performed. The fourth modified example of the circulation path shows an example in which the first pressure regulating means 120 and the second pressure regulating means 150, the second foam reservoir chamber 520B, the circulation pump 500, the bypass passage 160, and the first recovery passage 140 are not provided. Furthermore, the fourth modified example of the circulation path shows an example in which a third pressure regulating means 902 communicating with the second supply passage 112, a heated circulation pump 904 provided between the supply passage 130 and the pressure chamber 12, and a second recovery passage 905 connecting the pressure chamber 12 and the supply passage 130 are provided. In the fourth modified example of the circulation path, the same ink flow as in Figures 33 and 35 occurs. The second supply path 112, the third supply path 910, the supply channel 130, and the pressure chamber 12 are pressure-controlled by the third pressure adjustment means 902, thereby achieving stable ink ejection.

[0187] The third pressure adjustment means 902 is located outside the liquid ejection head 1 and communicates with the third supply passage 910 of the liquid ejection head 1 via the second supply passage 112. The third pressure adjustment means 902 may be a head-based system that utilizes the difference in head, for example, but any method is applicable. This modification is applicable to both ink cartridge systems and ink supply systems such as the CISS system.

[0188] The first foam reservoir chamber 520A is positioned vertically above the supply channel 130 so as to be in fluid communication with the supply channel 130, and the first foam removal unit 770A is formed extending vertically above the first foam reservoir chamber 520A. This allows foam mixed in with the ink in the first pressure adjustment means 120, supply channel 130, second recovery channel 905, etc., to be collected in the foam reservoir chamber 520 by circulation and discharge operations, and discharged from the ink by foam removal operations. The foam mixed in with the ink includes the aforementioned upstream foam, elution foam, and unintended foam, but is not limited to these. It is possible to discharge from the ink any amount of foam that can be collected in the foam reservoir chamber 520 and that is sufficient to achieve a sufficient foam removal speed. Therefore, the possibility of foam entering the discharge port 13 can be greatly reduced.

[0189] The first bubble removal unit 770A communicates with the ink supply unit 400 of the main body of the liquid dispensing device 50, and is depressurized by the operation of the ink supply unit 400. Furthermore, a third check valve 213 is provided between the bubble removal unit 770 and the ink supply unit 400, so that the depressurized state is maintained even when the main body of the liquid dispensing device 50 is not constantly operating, thereby enabling the bubble removal operation. The third check valve 213 may also be provided in the third air passage 113 between the first bubble removal unit 770A and the ink supply unit 400.

[0190] There may be two or more foam retention chambers 520 and foam removal units 770. Furthermore, the foam retention chambers 520 and foam removal units 770 do not necessarily have to be located in the supply channel 130. For example, the foam retention chambers 520 and foam removal units 770 may be located vertically above the ink tank 2, the first supply channel 111, the second supply channel 112, the third supply channel 910, the filter 110, the pressure chamber 12, the second recovery channel 905, etc. Also, the foam retention chambers 520 and foam removal units 770 do not necessarily have to be located vertically above the fluid communication section such as the supply channel 130. As long as the configuration allows for the collection of foam and contact with the gas permeable membrane, the foam retention chambers 520 may communicate with the side surface of the fluid communication section, and the foam removal units 770 may extend laterally from the foam retention chambers 520. This also applies when foam reservoirs 520 and foam removal units 770 are provided in multiple parts of the fluid communication section other than the supply channel 130 and the first recovery channel 140.

[0191] The heated circulation pump 904 delivers the ink by performing the same operation as shown in Figure 34. Note that the heated circulation pump 904 does not need to be located between the supply channel 130 and the pressure chamber 12; it may be located between the pressure chamber 12 and the second recovery channel 905.

[0192] <Fifth variation of the circulation path> Figures 43 and 44 schematically show a fifth modified example of the circulation path. Figure 43 shows the circulation path when circulation is performed without discharge. Figure 44 shows the circulation path when recording is performed with a high duty cycle. The fifth modified example of the circulation path shows an example in which the first pressure regulating means 120 and the second pressure regulating means 150 are not arranged, and the bypass passage 160 and the first recovery passage 140 are directly connected.

[0193] In the fifth modified example of the circulation path, the flow resistance of the ink flow path from the bypass flow path 160 to the first recovery flow path 140 is R1, and the flow resistance of the ink flow path from the supply flow path 130 to the first recovery flow path 140 via the discharge module 300 is R2. Since the flow rate of ink flowing through each flow path is inversely proportional to the flow resistance, the ratio of the flow rate of ink in the flow path via the bypass flow path 160 to the flow rate of ink in the flow path via the discharge module 300 is R2 to R1. In accordance with this relationship, the flow resistance of each flow path is set so that the circulation amount is such that the viscosity of the ink near the discharge port 13 in the discharge module 300 is suppressed. That is, the flow resistance of each flow path is set so that the flow velocity of the ink in the pressure chamber 12 is equal to or greater than a predetermined flow velocity. The flow resistance R1 of the flow path via the bypass flow path 160 is controlled by changing the cross-sectional area or length of the flow path, or by providing a throttling in the flow path.

[0194] In the fifth modified example of the circulation path, when recording is performed with a high duty cycle, the pressure chamber 12 is supplied from both sides, as shown in Figure 44. That is, the ink supplied from the third supply path 910 to the supply path 130 is supplied to the discharge port 13 of the discharge module 300. On the other hand, a portion of the ink supplied from the third supply path 910 to the bypass path 160 is supplied to the third supply path 910 via the circulation pump 500. In addition, a portion of the ink supplied from the third supply path 910 to the bypass path 160 is supplied to the first recovery path 140 and supplied to the discharge port 13 of the discharge module 300. Therefore, the ink discharged from the discharge port 13 is supplied from either the supply path 130 or the first recovery path 140.

[0195] The third pressure adjustment means 902 is located outside the liquid ejection head 1 and communicates with the third supply passage 910 of the liquid ejection head 1 via the second supply passage 112. The third pressure adjustment means 902 may be a head-based system that utilizes the difference in head, for example, but any method is applicable. This modification is applicable to both ink cartridge systems and ink supply systems such as the CISS system.

[0196] The first foam accumulation chamber 520A is located vertically above the supply channel 130 so as to be in fluid communication with the supply channel 130, and the first foam removal unit 770A extends vertically above the first foam accumulation chamber 520A. The second foam accumulation chamber 520B is located vertically above the first recovery channel 140 so as to be in fluid communication with the first recovery channel 140, and the second foam removal unit 770B extends vertically above the second foam accumulation chamber 520B. As a result, foam mixed in with the ink in the supply channel 130, the first recovery channel 140, the pump inlet channel 170, the pump outlet channel 180, etc., can be collected in the foam accumulation chamber 520 by circulation and discharge operations, and discharged from the ink by foam removal operations. The bubbles that can get mixed into the ink include the aforementioned upstream bubbles, eluting bubbles, and unintended bubbles, but are not limited to these. It is possible to discharge from the ink an amount of bubbles that can be collected in the bubble reservoir chamber 520 and that is sufficient to achieve a sufficient de-bubbling speed. This makes it very difficult for bubbles to enter the discharge port 13.

[0197] The first bubble removal unit 770A and the second bubble removal unit 770B are in communication with the ink supply unit 400 of the main body of the liquid dispensing device 50, and are depressurized by the operation of the ink supply unit 400. Furthermore, a third check valve 213 is provided between the bubble removal unit 770 and the ink supply unit 400, so that the depressurized state is maintained even when the main body of the liquid dispensing device 50 is not constantly operating, thereby enabling the bubble removal operation. The third check valve 213 may be provided at the branched portions of the third air passage 113 between the ink supply unit 400 and the first bubble removal unit 770A and the second bubble removal unit 770B. The third check valve 213 may be provided at the concentrated portion of the third air passage 113 between the ink supply unit 400 and the first bubble removal unit 770A and the second bubble removal unit 770B.

[0198] The foam accumulation chamber 520 and the foam removal unit 770 do not need to be provided in both the supply channel 130 and the first recovery channel 140; they may be provided only in the supply channel 130 or only in the first recovery channel 140. Furthermore, three or more foam accumulation chambers 520 and foam removal units 770 may be provided. The foam accumulation chamber 520 and the foam removal unit 770 do not need to be provided in both the supply channel 130 and the first recovery channel 140. For example, the foam accumulation chamber 520 and the foam removal unit 770 may be provided vertically above the ink tank 2, the first supply channel 111, the second supply channel 112, the third supply channel 910, etc. The foam accumulation chamber 520 and the foam removal unit 770 may also be provided vertically above the filter 110, the pump inlet channel 170, the pump outlet channel 180, the bypass channel 160, the pressure chamber 12, etc. Furthermore, the foam accumulation chamber 520 and the foam removal unit 770 do not necessarily have to be located vertically above the fluid communication section such as the supply channel 130. As long as the configuration allows for the collection of foam and its contact with the gas permeable membrane, the foam accumulation chamber 520 may communicate with the side of the fluid communication section, and the foam removal unit 770 may be formed extending laterally from the foam accumulation chamber 520. This is also true when the foam accumulation chamber 520 and the foam removal unit 770 are provided in multiple parts of the fluid communication section other than the supply channel 130 and the first recovery channel 140.

[0199] <Sixth variation of the circulation pathway> Figures 45 and 46 schematically show a sixth modified example of the circulation path. Figure 45 shows the circulation path when circulation is performed without discharge. Figure 46 shows the circulation path when recording a high duty cycle. The sixth modified example of the circulation path shows an example in which the first pressure regulating means 120 is not provided, and a third pressure regulating means 902 communicating with the second supply path 112 is provided.

[0200] In the sixth modified example of the circulation path, when recording is performed with a high duty cycle, the pressure chamber 12 is supplied from both sides, as shown in Figure 46. That is, the ink supplied from the third supply path 910 to the supply path 130 is supplied to the discharge port 13 of the discharge module 300. On the other hand, a portion of the ink supplied from the third supply path 910 to the bypass path 160 is supplied to the third supply path 910 via the second pressure adjustment means 150, the pump inlet path 170, the circulation pump 500, and the pump outlet path 180. In addition, a portion of the ink supplied to the bypass path 160 is supplied to the first recovery path 140 via the second pressure adjustment means 150 and supplied to the discharge port 13 of the discharge module 300. Therefore, the ink discharged from the discharge port 13 is supplied from either the supply path 130 or the first recovery path 140.

[0201] The third pressure adjustment means 902 is located outside the liquid ejection head 1 and communicates with the third supply passage 910 of the liquid ejection head 1 via the second supply passage 112. The third pressure adjustment means 902 may be a head-based system that utilizes the difference in head, for example, but any method is applicable. This modification is applicable to both ink cartridge systems and ink supply systems such as the CISS system.

[0202] The first foam reservoir chamber 520A is located vertically above the supply channel 130 so as to be in fluid communication with the supply channel 130, and the first foam removal unit 770A extends vertically above the first foam reservoir chamber 520A. The second foam reservoir chamber 520B is located vertically above the first recovery channel 140 so as to be in fluid communication with the first recovery channel 140, and the second foam removal unit 770B extends vertically above the second foam reservoir chamber 520B. As a result, foam mixed in with the ink in the second pressure adjustment means 150, supply channel 130, first recovery channel 140, pump outlet channel 180, etc., can be collected in the foam reservoir chamber 520 by circulation and discharge operations, and discharged from the ink by foam removal operations. The bubbles that can get mixed into the ink include the aforementioned upstream bubbles, eluting bubbles, and unintended bubbles, but are not limited to these. It is possible to discharge from the ink an amount of bubbles that can be collected in the bubble reservoir chamber 520 and that is sufficient to achieve a sufficient de-bubbling speed. This makes it very difficult for bubbles to enter the discharge port 13.

[0203] The first bubble removal unit 770A and the second bubble removal unit 770B are in communication with the ink supply unit 400 of the main body of the liquid dispensing device 50, and are depressurized by the operation of the ink supply unit 400. Furthermore, a third check valve 213 is provided between the bubble removal unit 770 and the ink supply unit 400, so that the depressurized state is maintained even when the main body of the liquid dispensing device 50 is not constantly operating, thereby enabling the bubble removal operation. The third check valve 213 may be provided at the branched portions of the third air passage 113 between the ink supply unit 400 and the first bubble removal unit 770A and the second bubble removal unit 770B. The third check valve 213 may be provided at the concentrated portion of the third air passage 113 between the ink supply unit 400 and the first bubble removal unit 770A and the second bubble removal unit 770B.

[0204] The foam accumulation chamber 520 and the foam removal unit 770 do not need to be provided in both the supply channel 130 and the first recovery channel 140; they may be provided only in the supply channel 130 or only in the first recovery channel 140. Furthermore, three or more foam accumulation chambers 520 and foam removal units 770 may be provided. The foam accumulation chamber 520 and the foam removal unit 770 do not need to be provided in both the supply channel 130 and the first recovery channel 140. For example, the foam accumulation chamber 520 and the foam removal unit 770 may be provided vertically above the ink tank 2, the first supply channel 111, the second supply channel 112, the third supply channel 910, etc. The foam accumulation chamber 520 and the foam removal unit 770 may also be provided vertically above the filter 110, the pump inlet channel 170, the pump outlet channel 180, the bypass channel 160, the pressure chamber 12, etc. Furthermore, the foam accumulation chamber 520 and the foam removal unit 770 do not necessarily have to be located vertically above the fluid communication section such as the supply channel 130. As long as the configuration allows for the collection of foam and its contact with the gas permeable membrane, the foam accumulation chamber 520 may communicate with the side of the fluid communication section, and the foam removal unit 770 may be formed extending laterally from the foam accumulation chamber 520. This is also true when the foam accumulation chamber 520 and the foam removal unit 770 are provided in multiple parts of the fluid communication section other than the supply channel 130 and the first recovery channel 140.

[0205] <Other variations of the circulation path> Next, other variations of the circulation channel will be described. As mentioned above, the configuration in which ink flows back from the first recovery channel 140 to the pressure chamber 12 only requires that a bypass channel 160 is provided. Furthermore, the configuration in which ink flows back from the first recovery channel 140 to the pressure chamber 12 only requires that a mechanism that functions as a check valve is not provided between the junction of the bypass channel 160 and the pressure chamber 12. Therefore, if the circulation channel is such that this relationship can be maintained, ink can be supplied to the pressure chamber 12 from both sides, thereby improving the discharge stability.

[0206] Figures 47, 48, and 49 are schematic block diagrams illustrating other modified versions of the circulation path. In Figures 47, 48, and 49, the de-aeration unit 770 and the gas flow path connected to the de-aeration unit 770 (e.g., the third air flow path 113) are not shown.

[0207] Figure 47 shows an example in which the pump outlet passage 180, located downstream of the circulation pump 500, is connected to the ink tank 2 instead of the first pressure control chamber 122. In this configuration as well, the discharge stability can be improved, similar to the configurations described so far.

[0208] Figure 48 shows an example where the circulation pump 500, which was previously mounted inside the liquid discharge head 1, is installed on the main body side of the liquid discharge device 50. Part of the pump inlet passage 170 and the pump outlet passage 180 are also located outside the liquid discharge head 1. In this configuration as well, discharge stability can be improved, similar to the configurations described so far.

[0209] Figure 49 shows an example in which the circulation pump 500, which was previously mounted in the liquid ejection head 1, is installed on the main body side of the liquid ejection device 50, and the pump outlet passage 180 is connected to the ink tank 2. In this configuration as well, ejection stability can be improved, similar to the configurations described so far.

[0210] <Other variations> Furthermore, the liquid ejection head 1 shown in Figure 1(a) is shown as an example of a so-called serial type liquid ejection head that ejects ink while moving in the main scanning direction, but this is not limited to this. It may also be a so-called full-line type liquid ejection head in which ejection ports are formed throughout the entire width direction of the recording medium P, and ejection is possible over the entire width direction of the recording medium P without moving in the main scanning direction.

[0211] <<Other Embodiments>> The disclosures described in each of the above embodiments include configurations represented by the following example of a liquid dispensing device.

[0212] <Configuration 1> A liquid dispensing head having a liquid storage chamber for storing liquid, and a liquid dispensing unit for dispensing liquid supplied from the liquid storage chamber, The connection part with the liquid discharge head, A pressure reducing mechanism communicating with the aforementioned connection part, A liquid dispensing device equipped with, The connection section has a liquid channel for supplying liquid to the liquid storage chamber and a gas channel that communicates with the depressurization mechanism. The liquid discharge device is characterized in that the gas flow path is provided with a valve member capable of switching the gas flow between a closed state and an open state, and the valve member can be switched between the closed state and the open state by pressurizing or depressurizing a part of the gas flow path using the depressurization mechanism.

[0213] <Configuration 2> The liquid dispensing device according to configuration 1, further comprising a control mechanism for controlling pressurization or depressurization of the depressurization mechanism.

[0214] <Structure 3> The liquid discharge device according to configuration 1 or 2, wherein the gas flow path further comprises a biasing member that biases the valve member from the open state to the closed state.

[0215] <Structure 4> The gas flow path further includes a biasing member that biases the valve member from the open state to the closed state. The liquid discharge device according to configuration 2, wherein the control mechanism can switch the valve member from the closed state to the open state against the biasing force of the biasing member by reducing the pressure of a part of the gas flow path.

[0216] <Composition 5> The aforementioned liquid dispensing head is A nozzle for dispensing liquid, A pressure chamber is provided with an energy generating element that generates energy for discharging liquid from the aforementioned outlet, A liquid storage chamber is connected to one end of the pressure chamber and stores the liquid supplied to the pressure chamber, A foam reservoir chamber is configured to communicate with the liquid storage chamber and to retain foam inside, A depressurized chamber adjacent to the aforementioned foam reservoir chamber via a gas permeable membrane and connected to the aforementioned gas flow path, A liquid dispensing device according to any one of the configurations 1 to 4 having the following:

[0217] <Composition 6> The liquid discharge device according to configuration 5, wherein the pressure reduction mechanism is capable of simultaneously reducing the pressure in the pressure reduction chamber and reducing the pressure in the gas flow path. [Explanation of symbols]

[0218] 1. Liquid dispensing head 13 Outlet 450 Ink Supply Tubes 460 Degassing tube 470 Main unit side connecting component 480 First main unit side connection part 490 Second main unit side connection part 540 Unit Enclosure 541 Degassing channel 551 Liquid channel 800 Head-side connecting member 810 First head side connection section 820 Second head side connection section 810 Ink Needle 820 Degassing Needle 830 Degassing channel of connecting member 910 Seal part 920 Main unit connection component 930 Biasing member

Claims

1. A liquid dispensing head having a liquid storage chamber for storing liquid, and a liquid dispensing unit for dispensing liquid supplied from the liquid storage chamber, The connection part with the liquid discharge head, A pressure reducing mechanism communicating with the aforementioned connection part, A liquid dispensing device equipped with, The connection section has a liquid channel for supplying liquid to the liquid storage chamber and a gas channel that communicates with the depressurization mechanism. The liquid discharge device is characterized in that the gas flow path is provided with a valve member capable of switching the gas flow between a closed state and an open state, and the valve member can be switched between the closed state and the open state by pressurizing or depressurizing a part of the gas flow path using the depressurization mechanism.

2. The liquid dispensing device according to claim 1, further comprising a control mechanism for controlling the pressurization or depressurization of the depressurization mechanism.

3. The liquid discharge device according to claim 1, wherein the gas flow path further comprises a biasing member that biases the valve member from the open state to the closed state.

4. The gas flow path further includes a biasing member that biases the valve member from the open state to the closed state. The liquid discharge device according to claim 2, wherein the control mechanism can switch the valve member from the closed state to the open state against the biasing force of the biasing member by reducing the pressure of a part of the gas flow path.

5. The aforementioned liquid dispensing head is A nozzle for dispensing liquid, A pressure chamber is provided with an energy generating element that generates energy for discharging liquid from the aforementioned outlet, A liquid storage chamber is connected to one end of the pressure chamber and stores the liquid supplied to the pressure chamber, A foam reservoir chamber is configured to communicate with the liquid storage chamber and to retain foam inside, A depressurized chamber adjacent to the aforementioned foam reservoir chamber via a gas permeable membrane and connected to the aforementioned gas flow path, A liquid dispensing device according to claim 1, having the following features.

6. The liquid discharge device according to claim 5, wherein the pressure reduction mechanism is capable of simultaneously reducing the pressure in the pressure reduction chamber and reducing the pressure in the gas flow path.

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