Liquid discharge head and liquid discharge device

Abstract

To provide a liquid discharge head and a liquid discharge device which suppress occurrence of discharge failures without increasing the size of the device.SOLUTION: Between a circulation unit and a supply passage communicating with a pressure chamber, a passage is provided which has a vertical cross-sectional area in a liquid circulation direction twice or more a vertical cross-sectional area in the liquid circulation direction in the supply passage, is inclined relative to a gravity direction, and has a passage inner wall where a component force of a normal vector has a gravity direction component.SELECTED DRAWING: Figure 10

Description

Technical Field

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

Background Art

[0002] Patent Document 1 discloses a liquid ejection head in which a fluid reservoir, a pump, a circulation channel, and a printing head are provided on a carriage, the fluid is circulated through the circulation channel by the pump, and the fluid is supplied from the fluid reservoir to the printing head during a printing cycle.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the liquid ejection head of Patent Document 1, since it has a separator structure for separating gas and liquid and an air venting region, there are concerns about an increase in the size of the head and ink sticking in the separator structure. Also, although the circulation path is inclined to guide bubbles to the gas-liquid separator structure, this circulation path does not pass through the pressure chamber including the nozzles that eject the fluid in the printing head. That is, in Patent Document 1, since there is no circulation of the fluid in the pressure chamber, there is a risk of ejection failure when bubbles or the like enter the pressure chamber.

[0005] Therefore, the present invention provides a liquid ejection head and a liquid ejection device that suppress the occurrence of ejection failure without increasing the size of the device.

Means for Solving the Problems

[0006] Therefore, the liquid discharge head of the present invention comprises: a recording element substrate having a pressure chamber with a discharge port formed therein and discharging liquid from the discharge port; a first supply channel provided on the recording element substrate and communicating with the pressure chamber; a first recovery channel provided on the recording element substrate and communicating with the pressure chamber; a circulation pump that generates a pressure difference between the supply channel and the recovery channel so as to supply liquid from the supply channel to the pressure chamber and recover the liquid from the pressure chamber from the recovery channel; and a second supply channel connecting the first supply channel and the circulation pump, wherein the second supply channel has a vertical cross-sectional area in the liquid circulation direction that is at least twice the vertical cross-sectional area in the liquid circulation direction of the first supply channel, is inclined with respect to the direction of gravity, and has an inner wall of the channel whose normal vector component has a component in the direction of gravity. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide a liquid dispensing head and a liquid dispensing device that suppress the occurrence of dispensing defects without increasing the size of the device. [Brief explanation of the drawing]

[0008] [Figure 1] This is a schematic perspective view of a liquid dispensing device to which a liquid dispensing head can be applied. [Figure 2] This is a perspective view of the liquid dispensing head. [Figure 3] This is a disassembled perspective view of the liquid dispensing head. [Figure 4] This is a schematic diagram showing the steady-state circulation path for a single ink color. [Figure 5] These are cross-sectional views of the recording element substrate at different positions in the Y direction. [Figure 6] This shows the ink flow when recording using most of the ink nozzles. [Figure 7] This is a side view showing the liquid dispensing head. [Figure 8] This is a cross-sectional view showing the liquid dispensing head. [Figure 9] This is a schematic diagram showing the inside of the circulation unit. [Figure 10] It is a cross-sectional view showing a first ink connection flow path and a second ink connection flow path. [Figure 11] It is a cross-sectional view showing a first ink connection flow path and a second ink connection flow path. [Figure 12] It is a cross-sectional view showing a first ink connection flow path and a second ink connection flow path. [Figure 13] It is a view showing a cross-section at XIII-XIII of FIG. 7. [Figure 14] It is a cross-sectional view in the direction of the discharge port row of the first ink connection flow path. [Figure 15] It is a cross-sectional view in the direction of the discharge port row of the first ink connection flow path. [Figure 16] It is a view showing an example of pressure adjusting means. [Figure 17] It is an external perspective view of a circulation pump. [Figure 18] It is a cross-sectional view at line XVIII-XVIII of the circulation pump. [Figure 19] It is a view for explaining the flow of ink in a liquid discharge head. [Figure 20] It is a schematic view showing a circulation path for one color of ink in a discharge unit. [Figure 21] It is a view showing an opening plate. [Figure 22] It is a view showing a discharge element substrate. [Figure 23] It is a cross-sectional view showing the ink flow in different parts of a discharge unit. [Figure 24] It is a cross-sectional view showing the vicinity of a discharge port in a discharge module. [Figure 25] It is a view showing a discharge element substrate as a comparative example. [Figure 26] It is a view showing the flow path configuration of a liquid discharge head corresponding to three colors of ink. [Figure 27] It is a view showing the connection state of an ink tank, an external pump, and a liquid discharge head.

Embodiments for Carrying Out the Invention

[0009] Embodiments of the present invention will be described below with reference to the drawings.

[0010] Figure 1 is a schematic perspective view of a liquid ejection device 2000 to which the liquid ejection head 1000 in this embodiment can be applied. The liquid ejection device 2000 in this embodiment is a serial scan type inkjet recording device that ejects liquid (hereinafter also referred to as ink) from liquid ejection heads 1000 and 1001 to record an image on a recording medium P. The liquid ejection heads 1000 and 1001 can be mounted on a carriage 10, and the carriage 10 moves along a guide axis 11 in the main scanning direction in the X direction. The recording medium P is transported by transport rollers (not shown) in the sub-scanning direction in the Y direction, which intersects (orthogonal in this embodiment) the main scanning direction.

[0011] The carriage 10 is equipped with two types of liquid ejection heads: liquid ejection head 1000 can eject three types of ink, and liquid ejection head 1001 can eject six types of ink. Each liquid ejection head is supplied with pressurized ink from nine ink tanks 2 (21, 22, 23, 24, 25, 26, 27, 28, 29) via ink supply tubes 30. The ink supply unit 12 is equipped with a supply pump for pressurized supply, which will be described later.

[0012] As variations, the three inks in the liquid ejection head 1000 can be set to the same type of ink, reducing the number of ink tanks to seven. Alternatively, by adding more liquid ejection heads, it is possible to create a liquid ejection device capable of ejecting 12 or more types of ink.

[0013] The liquid ejection head 1000 is fixedly supported on the carriage 10 by positioning means and electrical contacts of the carriage 10, and performs recording by ejecting ink while moving in the scanning direction, which is the X direction.

[0014] Figure 2 is a perspective view of the liquid ejection head 1000 in this embodiment, and Figure 3 is an exploded perspective view of the liquid ejection head 1000. The liquid ejection head 1000 comprises a recording element unit 100, a circulation unit 200, a head housing unit 300, and a cover 302. The recording element unit 100 comprises a recording element substrate 110, a support member 102 having ink supply connection paths 310, 320 to the recording element substrate 110, an electrical wiring tape 103, and an electrical contact substrate 104. The electrical contact substrate 104 has electrical contacts with the carriage 10 and supplies drive signals and energy to the circulation pump 203 mounted on the circulation unit 200 via a circulation unit connector 106 and pump wiring (not shown). The electrical contact substrate 104 also supplies drive signals and energy for ink ejection to the recording element substrate 110 via the electrical wiring tape 103.

[0015] Electrical connections are made by anisotropic conductive film (not shown), wire bonding, soldering, etc., but the connection method is not limited to these. In this embodiment, the connection between the recording element substrate 110 and the electrical wiring tape 103 is made by wire bonding, and the electrical connection is sealed with a sealing material to protect it from corrosion by ink and external impacts.

[0016] The circulation unit 200 includes a first pressure adjustment mechanism 201, a second pressure adjustment mechanism 202 (see Figure 4, described later), and a circulation pump 203. Ink is supplied from the ink tank 2 to the ink supply port 32 via an ink supply tube 30 (see Figure 1) and a head housing unit 300 having a tube connection part 31. In this embodiment, the circulation unit 200 is fixed to the head housing unit 300 with screws 501 to form an ink supply path. Elastic materials such as rubber or elastomer are used as sealing members at the connection parts in the ink supply path. The recording element unit 100 is adhesively fixed to the head housing unit 300 and forms an ink supply path. Elastic materials may also be used at the connection parts in the ink supply path. The head housing unit 300 is constructed by combining parts that have been injection-molded from filler-filled resin in order to position it with respect to the carriage 10 and to form the shape of the ink flow path.

[0017] The recording element substrate 110 has a series of ejection ports arranged in the Y direction. Multiple series of ejection ports are provided in the X direction.

[0018] Figure 4 is a schematic diagram showing the steady-state circulation path for one color of ink applied to the liquid dispensing device 2000 of this embodiment. Ink is supplied under pressure from the ink tank 21 to the liquid dispensing head 1000 by the supply pump P0. After dirt and other debris are removed by the filter 204, the ink is supplied to the first pressure control mechanism 201. In Figure 4 (and similarly in Figure 6 described later), the first pressure control mechanism 201 is labeled "L" and the second pressure adjustment mechanism 202 is labeled "H". This indicates that "H" is high negative pressure and "L" is low negative pressure, which is the opposite of high and low relative to positive pressure. The first pressure control mechanism 201 adjusts the pressure in the first pressure chamber 211 to a predetermined pressure (negative pressure). The circulation pump 203 is a piezoelectric diaphragm pump that changes the volume inside the pump chamber by inputting a drive voltage to a piezoelectric element attached to the diaphragm, and two check valves move alternately due to pressure fluctuations to pump the liquid.

[0019] The circulation pump 203 delivers ink from the second pressure control chamber 221, which is on the low-pressure (high negative pressure) side, to the first pressure control chamber 211, which is on the high-pressure (low negative pressure) side. The second pressure control chamber 221 is pressure-regulated to a lower pressure than the first pressure control chamber 211 by the second pressure adjustment mechanism 202. The recording element substrate 110 has multiple pressure chambers 113, each having an outlet from which liquid can be discharged, and a common supply channel 111 and a common recovery channel 112 are connected to each pressure chamber 113.

[0020] The common supply channel 111 is connected to the first pressure control chamber 211 via the first ink connection channel 310 and the first bubble storage channel (bubble storage section) 301, and is therefore pressure-regulated to the high-pressure (upstream) side. The common recovery channel 112 is connected to the second pressure control chamber 221 via the second ink connection channel 320 and the second bubble storage channel 302, and is therefore pressure-regulated to the low-pressure (downstream) side. Due to the pressure difference between the common supply channel 111 and the common recovery channel 112, a flow occurs in each pressure chamber 113 in the direction of arrow α in Figure 4. This ink flow due to the pressure difference allows locally thickened ink near the discharge port that is not being discharged during standby and recording to be recovered from the pressure chamber 113, thereby suppressing discharge failures.

[0021] In this embodiment, the first bubble storage channel 301 and the second bubble storage channel 302 have a volume capable of temporarily storing bubbles in the ink path that are generated during recording and standby.

[0022] Figures 5(a) to 5(c) are cross-sectional views of the recording element substrate 110 at different positions in the Y direction. The recording element substrate 110 comprises a Si substrate 120 on which an electrical circuit (not shown) and a heater 115, which is a pressure chamber generation mechanism, are arranged, and an ejection port member 130 which has a pressure chamber 113 and an ejection port 114 corresponding to the heater 115, patterned by photolithography. In this embodiment, ejection energy is obtained by applying a voltage to the heater 115 and foaming the ink in the pressure chamber 113, but this is not limited to the pressure generation mechanism. A piezoelectric element may be used instead of the heater. The Si substrate 120 has a connection surface 123, which is bonded and fixed to the support member 102 and connected to each ink supply path.

[0023] In this embodiment, in order to improve ink supply to the pressure chamber 113 and reduce costs by reducing the substrate size, the common supply channel 111 and the common recovery channel 112 are configured with a pitch of 1 mm or less in the X direction. Furthermore, from the viewpoint of the efficiency of imprinting onto the recording medium P, four rows of ejection ports are arranged with ejection ports arranged at 600 dpi. However, the ejection port arrangement resolution and the number of ejection port rows are not limited to these.

[0024] Figure 5(a) shows a cross-section of the common supply channel opening 121 at a position where the common supply channel 111 is in communication with the connection surface 123. Figure 5(b) shows a cross-section of the common supply channel 111 and the common recovery channel 112 at a position where neither is in communication with the connection surface 123. Figure 5(c) shows a cross-section of the common recovery channel opening 122 at a position where the common recovery channel 112 is in communication with the connection surface 123.

[0025] In order to control the pressure difference between the common supply channel 111 and the common recovery channel 112, it is necessary to divide the ink supply path in addition to the pressure chamber 113 and the pressure control mechanism. For this reason, the first ink connection channel 310 and the second ink connection channel 320 are divided in the direction of the discharge port row at the cross-sectional position shown in Figure 5(b). The common supply channel 111 and the common recovery channel 112 have a very small cross-sectional area, and there is a concern that insufficient ink supply may occur due to pressure loss during liquid transfer. For this reason, it is desirable to make the common supply channel 111 and the common recovery channel 112, which are not in communication with the connection surface 123 shown in Figure 5(b), as short as possible. Accordingly, it is desirable that there be many common supply channel openings 121 shown in Figure 5(a) and common recovery channel openings 122 shown in Figure 5(c) in the direction of the discharge port row.

[0026] In the exploded perspective view of Figure 3, there are nine first ink connection channels 310 and eight second ink connection channels 320 per color. The number of these connection points varies depending on the length of the discharge port row and the width of the separation joint. In this embodiment, the cross-sectional area of ​​the common supply channel 111 and the common recovery channel 112 in Figure 5(b) is 0.1 mm². 2 The following conditions apply, and the distance between the common supply channel opening 121 and the common recovery channel opening 122 is 7.5 mm or less.

[0027] Figure 6 shows the ink flow in the circulation path for one color when recording using most of the ejection ports in this embodiment. When recording using most of the ejection ports, the flow differs from the circulation in a steady state, with ink being supplied to the pressure chamber 113 from both the common supply channel 111 and the common recovery channel 112.

[0028] When ink is discharged from the pressure chamber 113, ink is supplied from the common supply channel 111 and the common recovery channel 112, respectively. The common supply channel 111 supplies ink from the first pressure control chamber 211 to the pressure chamber 113 via the first ink connection channel 310 and the first bubble storage channel 301. The common recovery channel 112 supplies ink from the second pressure control chamber 221 to the pressure chamber 113 via the second ink connection channel 320 and the second bubble storage channel 302. The circulation pump 203 transports ink from the second pressure control chamber 221 to the first pressure control chamber 211, as in the steady state.

[0029] At this time, the second pressure control chamber 221 supplies ink to the second ink connection channel 320 and the circulation pump 203. Furthermore, the second pressure control chamber 221 maintains a constant pressure by receiving ink from the first pressure control chamber 211 via a bypass channel connecting the first pressure control mechanism 201 and the second pressure control mechanism 202, through the second pressure control mechanism 202. The first pressure chamber 211 supplies ink to the second pressure control mechanism 202 and the first ink connection channel 310, but maintains a constant pressure by recovering ink from the ink tank 21, which is the ink supply source, through the first pressure control mechanism 201, including the ink transported by the circulation pump 203.

[0030] Thus, the direction of ink flow in the common recovery channel 112 changes depending on the recording state, and consequently, the direction of ink flow in the second ink connection channel 320 and the second bubble storage channel 302 also changes.

[0031] Figure 7 is a side view showing the liquid ejection head 1000, Figure 8(a) is a cross-sectional view of Figure 7 between VIIIa and VIIIa, and Figure 8(b) is a cross-sectional view of Figure 7 between VIIIb and VIIIb. The recording element substrate 110 has rows of ejection ports along the Y direction, which is the direction of movement of the recording medium P, and ink is ejected from each ejection port in the Z direction. The first ink connection channel 310 and the second ink connection channel 320 are composed of the head housing unit 300 and the support member 102.

[0032] The recording element substrate 110 is supported by a support member 102 and is connected to a common supply channel opening 121 and a common supply channel 111 via a first bubble storage channel 301 and a first ink connection channel 310 from a first pressure control chamber 211. Furthermore, as shown in Figure 8(b), the recording element substrate 110 is also supported to a common recovery channel opening 122 and a common recovery channel 112 via a second bubble storage channel 302 and a second ink connection channel 320 from a second pressure control chamber 221.

[0033] The first pressure control chamber 211 and the second pressure control chamber 221 are controlled to a constant pressure by a pressure control mechanism configured within the circulation unit 200.

[0034] Figure 9 is a schematic diagram showing the inside of the circulation unit 200. In the circulation unit 200, ink is supplied under pressure from the ink supply unit 12 to the pressure control mechanism 201 via the filter 204 through the ink supply port 32. The pressure control mechanism 201 includes a valve 232, a valve spring 233, a flexible member 231, a pressure plate 235, and a pressure adjustment spring 234.

[0035] In the pressure control chamber 211, when the volume of the pressure control chamber 211 decreases due to ink discharge or other reasons, the pressure plate 235 deforms the flexible member 231 and the pressure regulating spring 234 to maintain a constant pressure within the pressure control chamber 211. The compression deformation of the pressure regulating spring 234 deforms the valve spring 233 in a direction that compresses it via the valve 232, thereby opening the valve 232 and supplying ink to the pressure control chamber 211. This behavior makes it possible to supply ink and maintain a constant pressure within the pressure control chamber 211. The negative pressure in the pressure control chamber 211 is set by the contact position of the pressure regulating spring 234 and the valve 232 with the pressure plate 235.

[0036] The pressure adjustment mechanism 202 of the pressure control chamber 221 includes a valve 242, a valve spring 243, a flexible member 241, a pressure plate 245, and a pressure adjustment spring 244. The pressure adjustment principle in the pressure adjustment mechanism 202 is the same as that of the pressure adjustment mechanism 201, except that the ink supply source has changed from the ink supply unit 12 to the pressure control chamber 211.

[0037] The circulation pump 203 is connected to transfer ink from the pressure control chamber 221 to the pressure control chamber 211. In this embodiment, a small diaphragm pump using a piezoelectric element is used as the circulation pump 203. Since the pump can be driven by applying a voltage pulse to the piezoelectric element, the circulation pump 203 can be controlled ON / OFF by the input voltage pulse. When the circulation pump 203 transfers ink from the pressure control chamber 221 to the pressure control chamber 211, the pressure control chamber 211 becomes pressurized by the amount of liquid transferred, and the pressure control chamber 221 becomes negatively pressurized by the amount of liquid transferred.

[0038] The pressure control chamber 221 recovers ink via the pressure adjustment mechanism 202 as it becomes negative pressure. The pressure adjustment mechanism 202 recovers ink from both the pressure control chamber 211 and the pressure chamber 113, thus creating a circulating flow while maintaining a constant pressure. This circulating flow via the pressure chamber 113 makes it possible to remove ink that has become thickened due to evaporation near the discharge port, enabling stable discharge.

[0039] Figure 10(a) is a cross-sectional view showing the first ink connection channel 310 connected to the pressure control chamber 211 in this embodiment, and Figure 10(b) is a cross-sectional view showing the second ink connection channel 320 connected to the pressure control chamber 221. Figure 10(c) is a perspective view showing the flow channels at the connection between the head housing unit 300 and the support member 102. The recording element substrate 110 comprises an ejection port member 130 and a Si substrate 120. A heating element heater (not shown) is placed on the Si substrate 120 to stabilize ejection. Furthermore, in order to equalize the temperature of the entire recording element substrate 110 and to ensure stable bonding with the Si substrate 120, the support member 102 is made of alumina material, which has a similar linear expansion to Si and high thermal conductivity.

[0040] In Figures 10(a) and (b), the arrows (solid lines) shown within the flow path indicate the flow of circulating ink driven by the circulation pump 203 when not recording. Specifically, in Figure 10(a), ink flows from the pressure control chamber 211 to the common supply passage opening 121 via the head housing unit 300 which constitutes the first bubble storage flow path 301 and the support member 102 which constitutes part of the first ink connection flow path 310. This ink flow then passes through the pressure chamber 113 from which ink is discharged from the common supply passage 111, to the common recovery flow path 112, and is recovered at the common recovery flow path opening 122. The second ink connection flow path 320, which comprises the head housing unit 300 which constitutes the second bubble storage flow path 302 and the support member 102, supplies the ink recovered from the common recovery flow path opening 122 to the pressure control chamber 221. The circulation pump 201 completes one full rotation by transporting ink from the pressure control chamber 221 to the pressure control chamber 211.

[0041] Since the circulation flow is completed within the ink flow path of the liquid ejection head 1000, any bubbles 500 generated within the flow path of the liquid ejection head 1000 will be present somewhere in the circulation flow. Bubbles 500 are generated by foaming during ink filling, foaming due to ink flow, supersaturation of dissolved gases in the ink due to temperature rise or pressure reduction inside the liquid ejection head 1000. If bubbles 500 flow into the pressure chamber 113, it can cause ink ejection failure and lead to image defects. Therefore, it is desirable to store these bubbles 500 in the circulation flow path far from the pressure chamber 113 to prevent them from flowing into the pressure chamber 113.

[0042] In typical liquid ejection heads, if there is no channel to store air bubbles, it is necessary to control the degree of ink degassing and use the ink within a range that does not cause supersaturation of dissolved gases, or to discharge any generated air bubbles outside the head each time. Methods for controlling the degree of degassing include reduced-pressure stirring and degassing modules using hollow fiber membranes, but these are costly and increase the size and weight of the head, which may affect printing speed. Also, if ink containing air bubbles is discharged each time, the ink used for recording is used as waste ink, which may affect printing costs.

[0043] Therefore, in this embodiment, by inclining the ceilings of the first bubble storage channel 301 and the second bubble storage channel 302, bubbles 500 generated in the bubble storage channel are guided by buoyancy to a position far from the pressure chamber 113 in the circulation channel, and are temporarily stored at that distant position. Here, the ceiling refers to the surface that forms part of the channel, and is the inner wall of the channel where the component force of the normal vector at the ceiling surface has a component in the direction of gravity. Most of the bubbles generated by environmental changes such as rising temperature are microbubbles with a diameter of 1 mm or less, and it is necessary to increase the buoyancy to overcome the drag force generated on the bubbles 500 due to the ink flow.

[0044] In this embodiment, a circulating flow is generated even when not recording, in order to prevent ink viscosity increase near the discharge port. As a result, ink flows toward the recording element substrate 110 in the first ink connection channel 310 and the first bubble storage channel 301, making it difficult to guide the bubbles 500 to a position far from the pressure chamber 113. Since the drag force generated from the ink flow is proportional to the square of the ink flow velocity v, reducing the ink flow velocity is effective in weakening the drag force. By reducing the ink flow velocity and thus weakening the drag force, it becomes easier to guide the bubbles 500 to a position far from the pressure chamber 113 by buoyancy.

[0045] Furthermore, in this embodiment, the minimum vertical cross-sectional area of ​​the first bubble storage channel 301 in the ink circulation direction is 20 times or more than the minimum vertical cross-sectional area of ​​the first ink connection channel 310 in the ink circulation direction. As shown in Figure 10(c), the head housing unit 300 constituting the first bubble storage channel 301 extends in the Y direction, and therefore the first bubble storage channel 301 also extends in the Y direction. In such a channel structure, the minimum cross-sectional area of ​​the first bubble storage channel 301 is configured to be 20 times or more than the minimum cross-sectional area of ​​the first ink connection channel 310. However, even if the minimum cross-sectional area of ​​the first bubble storage channel 301 is 2 times or more than the minimum cross-sectional area of ​​the first ink connection channel 310, the effects described in this embodiment can still be obtained. In addition, the first ink connection channel 310 at the connection between the head housing unit 300 and the support member 102 is provided at 9 locations along the Y direction. Therefore, the ink flow velocity can be reduced to 9 / 20 = 0.45 times. In this embodiment, the ceiling surfaces of the first bubble storage channel 301 and the first ink connection channel 310 have an angle (θ11, θ13) of approximately 40 to 50 degrees with respect to the surface where the discharge port is located.

[0046] In this way, by configuring the channel cross-sectional area such that the maximum flow velocity in the first bubble storage channel 301 is smaller than the maximum flow velocity in the first ink connection channel 310, the drag force on the bubbles 500 caused by the ink flow is reduced. This makes it possible to guide the bubbles 500 that have left the first ink connection channel 310 to the upper end of the ceiling in the first bubble storage channel 301. With this configuration, the flow velocity of the ink circulation flow in the first bubble storage channel 301 is made sufficiently slower than, or temporarily stopped than, the flow velocity of the ink circulation flow in the first ink connection channel 310, thereby guiding the bubbles 500 to a position far from the pressure chamber 113. This angle θ is determined by the friction coefficient determined by the ink properties and the inner wall of the first ink connection channel 310, and the moving force due to buoyancy.

[0047] In this embodiment, it has been confirmed that the effects of this embodiment can be obtained in the ink used in the liquid ejection recording head 1000 and the components of the first ink connection channel 310, by having the ceiling surface at an angle of approximately 15 degrees or more with respect to the surface on which the ejection port is located. More preferably, it is desirable to set the ceiling surface at an angle close to 90 degrees so that 100% of the buoyancy component of the bubbles 500 can be used as propulsion force.

[0048] Furthermore, in this embodiment, the minimum cross-sectional area of ​​the first ink connection channel 310 is ensured to be at least twice the total cross-sectional area (total area) of the common supply channel opening 121 to which it is connected. As a result, the ink flow velocity in the minimum cross-sectional area portion of the first ink connection channel 310 is slower than the ink flow velocity near the common supply channel opening 121, making it less likely for air bubbles 500 to be drawn into the common supply channel 111.

[0049] If the steady ink circulation flow is set to a relatively fast rate, depending on the volume of the bubbles 500, bubbles 500 may remain in the first ink connection channel 310. In such cases, if the ink circulation flow can be stopped for a short time to discharge the bubbles 500 to the first bubble storage channel 301, the bubbles 500 can be guided to the ceiling of the first bubble storage channel 301 even when the ink circulation is restarted. Since this circulation stop time cannot be performed during recording, it is desirable to complete it in a short time to avoid reducing productivity.

[0050] In this embodiment, the inner walls of the second bubble storage channel 302 and the second ink connection channel 320 (see Figure 10(b)) also have a ceiling surface that is at an angle of approximately 40 to 50 degrees (θ22, θ24) with respect to the surface where the discharge port is located. As a result, the movement of bubbles 500 to the second bubble storage channel 302 can be completed in a short time by both buoyancy and circulating fluid pressure.

[0051] Figure 11 illustrates the ink flow and the behavior of bubbles 500 when recording is performed using most of the ejection ports shown in Figure 6. Figure 11(a) is a cross-sectional view showing the first ink connection channel 310 connected to the pressure control chamber 211, and Figure 11(b) is a cross-sectional view showing the second ink connection channel 320 connected to the pressure control chamber 221. The positions of the cross-sections in Figures 11(a) and (b) are the same as in Figures 10(a) and (b). When recording is performed using most of the ejection ports, more ink is supplied to the pressure chamber 113 than the circulating flow in the non-recording state shown in Figure 10, and a large flow is generated in each channel. In addition, in the first ink connection channel 310 and the second ink connection channel 320, the ink circulating flow is directed toward the pressure chamber 113. Due to the increase in ink flow rate, the ink flow velocity increases overall toward the foaming chamber 113.

[0052] In particular, in the first ink connection channel 310 and the second ink connection channel 320, which are composed of the support member 102 which has a relatively small flow channel cross-sectional area, a high flow velocity is generated, the dynamic pressure on the bubbles 500 increases, and the possibility of bubbles 500 flowing into the pressure chamber 113 increases. Also, in this embodiment, since the discharge energy in the pressure chamber 113 is generated by the thermal energy from the heater 115, the recording element substrate 110 heats up with discharge. As a result, the circulation channels formed in the support member 102 and the recording element substrate 110 become relatively hot, the dissolved gas in the ink becomes supersaturated, and the possibility of bubbles 500 forming increases.

[0053] When recording is performed using most of the ejection port in this manner, it is necessary to periodically move the bubbles 500 to the first bubble storage channel 301 or the second bubble storage channel 302 by circulating the ink during periods of non-recording or by stopping circulation, depending on the amount and duration of ink ejection. As mentioned earlier, this movement time of the bubbles 500 may involve stopping recording, which can reduce printing productivity. Therefore, in order to shorten the movement time of the bubbles 500, it is desirable to set the ceiling surface at an angle close to 90 degrees, so that the buoyancy component of the bubbles 500 can be used 100% as movement force.

[0054] As a variation, a heater for ink temperature control may be mounted on the recording element substrate 110, and a resin material with low thermal conductivity may be used for the support member 102 to prioritize temperature control speed. In that case, the location of bubble generation due to heat is limited to the vicinity of the Si substrate 120.

[0055] Furthermore, the common supply channel 111 formed within the recording element substrate 110 is formed using Si substrate processing technology. Therefore, it is difficult to achieve a sufficient angle with respect to the surface where the discharge port is located, and the channel cross-sectional area is very small, making it difficult to guide the bubbles 500 into the first bubble storage channel 301 by buoyancy relative to the circulating flow. For this reason, depending on the ink discharge amount and recording time, it is necessary to periodically discharge the bubbles 500 generated inside the common supply channel 111 through the discharge port from the pressure chamber 113 by suction or other means. However, since the ink volume in the common supply channel 111 is very small, it is possible to minimize waste ink.

[0056] Figure 12(a) is a cross-sectional view showing the first bubble storage channel 301 when a large amount of bubbles 500 are stored, and Figure 12(b) is a cross-sectional view showing the second bubble storage channel 302 when a large amount of bubbles 500 are stored. The positions of the cross-sections in Figures 12(a) and (b) are the same as in Figures 10(a) and (b). When bubbles 500 combine to a size that almost completely blocks the cross-sectional area of ​​the channel, the drag force due to the ink flow becomes large, and the bubbles are carried into the pressure chamber 113.

[0057] However, the cross-sectional area of ​​the flow channels, including the ceilings of the first bubble storage channel 301 and the second bubble storage channel 302, is larger than the minimum cross-sectional area within each bubble storage channel, and multiple slits (not shown) are provided on the flow channel walls along the direction of ink flow. The slits are made sufficiently narrow so that they are not blocked by the bubbles 500. As a result, the relative ink flow velocity within each bubble storage channel is slowed down, making it possible to flow ink through the slits without moving the bubbles 500. This suppresses the flow of bubbles 500 into the pressure chamber 113. In this embodiment, the slits are grooves with a width of 0.5 mm, and the structure is designed so that the stored and combined bubbles 500 are less likely to block the slits.

[0058] Even with the provision of slits, a certain amount of bubbles 500 will accumulate in the first bubble storage channel 301 and the second bubble storage channel 302. When these bubbles reach channels with smaller cross-sectional areas and higher flow velocities, they may flow into the pressure chamber 113 due to the ink dynamic pressure, potentially causing ejection failure. Therefore, when a certain amount of bubbles 500 accumulate, it is necessary to perform a recovery operation, such as suction from the ejection port, to expel the bubbles 500 to the outside. Suction recovery devices that perform recovery operations such as suction are widely used in inkjet printers for recording stability and are not a new configuration for removing bubbles 500 accumulated in the first bubble storage channel 301 and the second bubble storage channel 302.

[0059] Figure 13 shows a cross-section at XIII-XIII in Figure 7. By making the cross-sectional area of ​​the first bubble storage channel 301 and the second bubble storage channel 302 as wide as possible, it is possible to move the generated bubbles to the ceiling. For this reason, it is desirable to form the first bubble storage channel 301 and the second bubble storage channel 302 with a large cross-sectional area that extends close to the recording element substrate 110 where bubbles 500 are likely to be generated.

[0060] In this embodiment, when nine common supply channel openings 121 and eight common recovery channel openings 122 are alternately arranged in the direction of the discharge port row, each opening is connected by a channel having a length in the Y direction equal to or greater than the length of the long side at both ends of the discharge port row. In this case, it is necessary to arrange branching sections to supply each opening that is arranged at a narrow pitch, but in this embodiment, as shown in the cross-sectional views of Figures 8(a) and (b), the part that connects to the recording element substrate 110 is a branching section with a triangular shape having a hypotenuse inclined in the X direction, which is the scanning direction. The triangular hypotenuse of the first ink connection channel 310 connected to the common supply channel opening 121 and the triangular hypotenuse of the second ink connection channel 320 connected to the common recovery channel opening 122 are arranged in opposite directions.

[0061] Thus, a flow channel is provided between the circulation unit and the supply channel communicating with the pressure chamber, having a vertical cross-sectional area in the liquid circulation direction that is at least twice the vertical cross-sectional area in the liquid circulation direction of the supply channel, and having an inner wall of the flow channel that is inclined with respect to the direction of gravity and whose normal vector component has a component in the direction of gravity. This makes it possible to provide a liquid discharge head and liquid discharge device that suppress the occurrence of discharge failures without increasing the size of the device.

[0062] (modified version) A modified example of the above embodiment will be described.

[0063] Figure 14 is a cross-sectional view of the first ink connection channel 310 in the direction of the ejection port row (Y direction), and Figure 15 is a cross-sectional view of the first ink connection channel 310 in the direction of the ejection port row (Y direction) when the transport angle of the recording medium is changed. The external shape of the liquid ejection head 1000 is desirable because reducing the width in the scanning direction (X direction) reduces the width of the recording device. Also, when multiple liquid ejection heads 1000 are mounted, reducing the width in the scanning direction (X direction) is desirable because it reduces the width required to move the carriage 10, thereby improving productivity.

[0064] In the case of a liquid discharge head that dispenses two colors of ink, the width can be reduced by mounting the circulation unit 200 (see Figure 3) at a position offset in the Y direction. In this modified example, as mentioned above, the inner wall angles θ (θ31~θ37) of the first ink connection channel 310, the first bubble storage channel 301, the second ink connection channel 320, and the second bubble storage channel 302 are set to 45 degrees or more with respect to a plane perpendicular to the gravity direction vector.

[0065] Since the liquid ejection head 1000 records while moving in the scanning direction (X direction) relative to the recording medium P, its orientation may change depending on the transport angles α and β of the recording medium P, as shown in Figures 15(a) and (b). A higher degree of freedom in the transport angle of the recording medium P is desirable because it expands the range of applications it can be used for.

[0066] To maintain high precision in the impact of the ejected ink onto the recording medium P, the planes of the recording medium P and the ejection port 114 must be as parallel as possible, i.e., the planes of the recording medium P and the ejection port 114 must be as parallel as possible, i.e., the planes of the two must be as parallel as possible. In this case, to enable the effects of the present invention, the inner wall angles θ (θ42, θ44~θ46,)(θ51, θ53~θ55, θ57) must be at least 15 degrees with respect to a plane perpendicular to the gravity direction vector, taking into account the mounting angle of the liquid ejection head 1000. The liquid ejection head 1000 shown in Figure 14 is configured so as to achieve the effects of the present invention even when considering the inclination of angles α and β shown in Figures 15(a) and (b).

[0067] Let's organize the configuration of this embodiment using a definition based on the normal vector N30 of the arrangement plane of the discharge port 114. In the configuration shown in Figure 14, similar to the liquid discharge head 1000, the arrangement plane of the discharge port 114 is coplane with the vertical plane in the direction of gravity (Z direction), so the normal vector N30 is the same as the direction of gravity (Z direction). For the angle θ35 of the inner wall surface of the flow path to exert the effects of the present invention, the angle between the normal vector N35 and the direction of gravity (Z direction) must be 15 degrees or more. This is equivalent to saying that the angle between the normal vector N35 of the inner wall surface and the normal vector N30 of the arrangement plane of the discharge port 114 must be 15 degrees or more.

[0068] The normal vector of the plane of the ejection port 114 of the liquid ejection head 1000 is the same as the gravity direction vector (Z direction), so the ink ejection direction and the gravity direction are in the same direction. As a result, the ink droplets are not affected by gravity in the plane direction of the recording medium P, both while they are flying and after they hit the recording medium P, and high-precision printing can be achieved.

[0069] On the other hand, in the modified example shown in Figures 15(a) and (b), the arrangement plane of the discharge port 114 of the liquid discharge head 1000 is arranged on a plane parallel to the transport surface of the recording medium P. In this case, the angles between the normal vectors N44 and N45 of the inner wall of the flow path in Figure 15(a) and the normal vector N40 of the arrangement plane of the discharge port 114 are the same as θ34 and θ35 shown in Figure 14. Whether each inner wall of the flow path can exert the effects of the present invention can be verified by considering the angle between the normal vector N40 of the arrangement plane of the discharge port 114 and the vector in the direction of gravity (Z direction).

[0070] In the modified example shown in Figure 15(a), the angle between the normal vector N40 of the arrangement plane of the discharge port 114 and the vector in the direction of gravity (Z direction) is angle α, which is the same as the angle between the arrangement plane of the discharge port 114 and the plane perpendicular to the direction of gravity. Since angle θ45 is the sum of θ35 defined in Figure 14 and angle α, which is 15 degrees or more, it is possible to obtain the effects of the present invention. Similarly, since angle θ44 is the subtraction of θ34 defined in Figure 14 and angle α, which is 15 degrees or more, it is possible to obtain the effects of the present invention.

[0071] When considering the effect of angle α, if the angle between the gravity direction (Z direction) vector and the normal vector of the inner wall of the flow path (N44, N45) is the same as the normal vector N40 of the arrangement plane of the discharge port 114, subtract them. If they are not the same, add them together to verify whether the required angle or greater is ensured.

[0072] In the example shown in Figure 15(b), the effect of the present invention can be verified by checking the angle β in the same manner as described in Figure 14(a) above.

[0073] <Reference example> A more detailed example of the liquid dispensing device described above will be explained.

[0074] <Pressure regulating means> Figure 16 shows an example of a pressure regulating means. Referring to Figure 16, the configuration and operation of the pressure regulating means (first pressure regulating means 1120, second pressure regulating means 1150) built into the liquid discharge head 1000 described above will be explained in more detail. Note that the first pressure regulating means 1120 and the second pressure regulating means 1150 have substantially the same configuration. For this reason, the first pressure regulating means 1120 will be used as an example in the explanation below, and for the second pressure regulating means 1150, only the reference numerals of the parts corresponding to the first pressure regulating means in Figure 16 will be added. In the case of the second pressure regulating means 1150, the first valve chamber 1121 described below will be read as the second valve chamber 1151, and the first pressure control chamber 1122 will be read as the second pressure control chamber 1152.

[0075] The first pressure regulating means 1120 has a first valve chamber 1121 and a first pressure control chamber 1122 formed within a cylindrical housing 1125. The first valve chamber 1121 and the first pressure control chamber 1122 are separated by a partition wall 1123 provided within the cylindrical housing 1125. However, the first valve chamber 1121 communicates with the first pressure control chamber 1122 via a communication port 1191 formed in the partition wall 1123. The first valve chamber 1121 is provided with a valve 1190 that switches between communication and disconnection between the first valve chamber 1121 and the first pressure control chamber 1122 at the communication port 1191. The valve 1190 is held in a position facing the communication port 1191 by a valve spring 1200 and is configured to be able to come into close contact with the partition wall 1123 by the biasing force of the valve spring 1200. When the valve 1190 is in close contact with the partition wall 1123, the flow of ink through the communication opening 1191 is blocked. To improve the close contact with the partition wall 1123, it is preferable that the contact portion of the valve 1190 with the partition wall 1123 be formed of an elastic material. A valve shaft 1190a is provided protruding from the center of the valve 1190, which is inserted into the communication opening 1191. By pressing this valve shaft 1190a against the biasing force of the valve spring 1200, the valve 1190 is separated from the partition wall 1123, and the flow of ink through the communication opening 1191 becomes possible. Hereinafter, the state in which the flow of ink through the communication opening 1191 is blocked by the valve 1190 will be referred to as the "closed state," and the state in which the flow of ink through the communication opening 1191 is possible will be referred to as the "open state."

[0076] The opening of the cylindrical housing 1125 is closed by a flexible member 1230 and a pressure plate 1210. The flexible member 1230, the pressure plate 1210, the peripheral wall of the housing 1125, and the partition wall 1123 form the first pressure control chamber 1122. The pressure plate 1210 is configured to be displaceable in accordance with the displacement of the flexible member 1230. The materials of the pressure plate 1210 and the flexible member 1230 are not particularly limited, but for example, the pressure plate 1210 can be made of a resin molded part and the flexible member 1230 can be made of a resin film. In this case, the pressure plate 1210 can be fixed to the flexible member 1230 by heat welding.

[0077] A pressure adjustment spring 1220 (biasing member) is provided between the pressure plate 1210 and the partition wall 1123. Due to the biasing force of the pressure adjustment spring 1220, the pressure plate 1210 and the flexible member 1230 are biased in a direction that expands the internal volume of the first pressure control chamber 1122, as shown in Figure 16(a). Furthermore, when the pressure inside the first pressure control chamber 1122 decreases, the pressure plate 1210 and the flexible member 1230 are displaced against the pressure of the pressure adjustment spring 1220 in a direction that decreases the internal volume of the first pressure control chamber 1122. When the internal volume of the first pressure control chamber 1122 decreases to a certain amount, the pressure plate 1210 comes into contact with the valve shaft 1190a of the valve 1190. Subsequently, as the internal volume of the first pressure control chamber 1122 decreases further, the valve 1190 moves together with the valve shaft 1190a against the biasing force of the valve spring 1200, separating from the partition wall 1123. As a result, the communication port 1191 opens (as shown in Figure 16(b)).

[0078] In this embodiment, the connection settings within the circulation path are configured such that the pressure in the first valve chamber 1121 is higher than the pressure in the first pressure control chamber 1122 when the communication port 1191 is open. As a result, when the communication port 1191 is open, ink flows from the first valve chamber 1121 into the first pressure control chamber 1122. This ink inflow causes the flexible member 1230 and the pressure plate 1210 to displace in a direction that increases the internal volume of the first pressure control chamber 1122. Consequently, the pressure plate 1210 separates from the valve shaft 1190a of the valve 1190, the valve 1190 comes into close contact with the partition wall 1123 due to the biasing force of the valve spring 1200, and the communication port 1191 closes (the state shown in Figure 16(c)).

[0079] Thus, in the first pressure adjustment means 1120 of this embodiment, when the pressure in the first pressure control chamber 1122 decreases to below a certain pressure (for example, when the negative pressure becomes strong), ink flows in from the first valve chamber 1121 through the communication port 1191. This prevents the pressure in the first pressure control chamber 1122 from decreasing further. Therefore, the first pressure control chamber 1122 is controlled to maintain a pressure within a certain range.

[0080] Next, we will explain the pressure in the first pressure control chamber 1122 in more detail.

[0081] As described above, consider the state in which the flexible member 1230 and the pressure plate 1210 are displaced in response to the pressure in the first pressure control chamber 1122, and the pressure plate 1210 comes into contact with the valve shaft 1190a, causing the communication port 1191 to open (the state shown in Figure 16(b)). At this time, the relationship of the forces acting on the pressure plate 1210 is expressed by the following equation 1. P2×S2+F2+(P1-P2)×S1+F1=0...Equation 1 Furthermore, rearranging equation 1 for P2, P2=-(F1+F2+P1×S1) / (S2-S1)...Equation 2 This is the result. P1: Pressure (gauge pressure) in the first valve chamber 1121 P2: Pressure (gauge pressure) in the first pressure control chamber 1122 F1: Spring force of valve spring 1200 F2: Spring force of pressure regulating spring 1220 S1: Pressure-receiving area of ​​valve 1190 S2: Pressure receiving area of ​​pressure plate 1210

[0082] Here, the spring force F1 of the valve spring 1200 and the spring force F2 of the pressure regulating spring 1220 are considered positive (leftward in Figure 16) when pushing the valve 1190 and the pressure plate 1210. Furthermore, with respect to the pressure P1 in the first valve chamber 1121 and the pressure P2 in the first pressure control chamber 1122, the relationship P1 ≥ P2 is satisfied.

[0083] The pressure P2 in the first pressure control chamber 1122 when the communication port 1191 is open is determined by equation 2. When the communication port 1191 is open, ink flows from the first valve chamber 1121 to the first pressure control chamber 1122 because the relationship P1 ≥ P2 is configured. As a result, the pressure P2 in the first pressure control chamber 1122 does not decrease further, and P2 is maintained within a certain pressure range.

[0084] On the other hand, as shown in Figure 16(c), when the pressure plate 1210 is not in contact with the valve shaft 1190a and the communication port 1191 is closed, the relationship of the forces acting on the pressure plate 1210 is given by Equation 3. P3×S3+F3=0...Equation 3 Now, if we rearrange equation 3 for P3, P3 = -F3 / S3 ... Equation 4 This is the result. F3: Spring force of pressure regulating spring 1220 when pressure plate 1210 and valve shaft 1190a are not in contact. P3: Pressure (gauge pressure) in the first pressure control chamber 1122 when the pressure plate 1210 and the valve shaft 1190a are not in contact. S3: Pressure receiving area of ​​pressure plate 1210 when pressure plate 1210 and valve 1190 are not in contact.

[0085] In Figure 16(c), the pressure plate 1210 and the flexible member 1230 are shown displaced to the right as far as they can go. Depending on the amount of displacement between the pressure plate 1210 and the flexible member 1230 as they move to the state shown in Figure 16(c), the pressure P3 in the first pressure control chamber 1122, the spring force F3 of the pressure adjustment spring 1220, and the pressure-receiving area S3 of the pressure plate 1210 change. Specifically, when the pressure plate 1210 and the flexible member 1230 are to the left in Figure 16 compared to Figure 16(c), the pressure-receiving area S3 of the pressure plate 1210 becomes smaller, and the spring force F3 of the pressure adjustment spring 1220 becomes larger. As a result, according to the relationship in Equation 4, the pressure P3 in the first pressure control chamber 1122 decreases. Therefore, according to equations 2 and 4, the pressure in the first pressure control chamber 1122 gradually increases from the state in Figure 16(b) to the state in Figure 16(c) (that is, the negative pressure weakens and approaches the positive pressure). In other words, from the state in which the communication port 1191 is open, the pressure plate 1210 and the flexible member 1230 are gradually displaced to the right, and the pressure in the first pressure control chamber 1122 gradually increases until the internal volume of the first pressure control chamber 1122 reaches the limit of its displaceability. In other words, the negative pressure weakens.

[0086] <Circulation pump> Next, with reference to Figures 17 and 18, the configuration and operation of the circulation pump 1500 built into the liquid discharge head 1000 described above will be explained in detail.

[0087] Figure 17 is an external perspective view of the circulation pump 1500. Figure 17(a) is an external perspective view showing the front side of the circulation pump 1500, and Figure 17(b) is an external perspective view showing the rear side of the circulation pump 1500. The outer shell of the circulation pump 1500 consists of a pump housing 1505 and a cover 1507 fixed to the pump housing 1505. The pump housing 1505 consists of a housing body 1505a and a flow path connecting member 1505b that is adhesively fixed to the outer surface of the housing body 1505a. Each of the housing body 1505a and the flow path connecting member 1505b 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 1501, and the pair of through holes provided at the other position form the pump discharge hole 1502. The pump supply port 1501 is connected to the pump inlet passage 1170, which is connected to the second pressure control chamber 1152, and the pump discharge port 1502 is connected to the pump outlet passage 1180, which is connected to the first pressure control chamber 1122. The ink supplied from the pump supply port 1501 passes through the pump chamber 1503 (see Figure 18) described later and is discharged from the pump discharge port 1502.

[0088] Figure 18 is a cross-sectional view of the circulation pump 1500 shown in Figure 17(a) along the line IX-IX. A diaphragm 1506 is joined to the inner surface of the pump housing 1505, and a pump chamber 1503 is formed between the diaphragm 1506 and a recess formed on the inner surface of the pump housing 1505. The pump chamber 1503 communicates with a pump supply hole 1501 and a pump discharge hole 1502 formed in the pump housing 1505. A check valve 1504a is provided in the middle portion of the pump supply hole 1501, and a check valve 1504b is provided in the middle portion of the pump discharge hole 1502. Specifically, the check valve 1504a is positioned so that a part of it can move to the left in the figure within a space 1512a formed in the middle portion of the pump supply hole 1501. Furthermore, the check valve 1504b is positioned so that a portion of it can move to the right in the figure within the space 1512b, which is formed in the middle portion of the pump discharge hole 1502.

[0089] When the diaphragm 1506 is displaced and the volume of the pump chamber 1503 increases, causing the pump chamber 1503 to be depressurized, the check valve 1504a moves away from the opening of the pump supply hole 1501 in space 1512a (i.e., moves to the left in the figure). When the check valve 1504a moves away from the opening of the pump supply hole 1501 in space 1512a, it becomes an open state that allows ink to flow through the pump supply hole 1501. Also, when the diaphragm 1506 is displaced and the volume of the pump chamber 1503 decreases, causing the pump chamber 1503 to be pressurized, the check valve 1504a comes into close contact with the wall surface surrounding the opening of the pump supply hole 1501. As a result, it becomes a closed state that blocks the flow of ink through the pump supply hole 1501.

[0090] On the other hand, when the pump chamber 1503 is depressurized, the check valve 1504b closes to the wall surrounding the opening of the pump housing 1505, blocking the flow of ink through the pump discharge hole 1502. When the pump chamber 1503 is pressurized, the check valve 1504b moves away from the opening of the pump housing 1505 towards the space 1512b (i.e., to the right in the figure), allowing the flow of ink through the pump discharge hole 1502.

[0091] Furthermore, the material of each check valve 1504a and 1504b may be any material that can deform in accordance with the pressure in the pump chamber 1503, 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.

[0092] As mentioned above, the pump chamber 1503 is formed by the joint between the pump housing 1505 and the diaphragm 1506. Therefore, the pressure in the pump chamber 1503 changes as the diaphragm 1506 deforms. For example, if the diaphragm 1506 is displaced toward the pump housing 1505 (displaced to the right in the figure) and the volume of the pump chamber 1503 decreases, the pressure inside the pump chamber 1503 increases. This causes the check valve 1504b, which is positioned opposite the pump discharge hole 1502, to open, and the ink in the pump chamber 1503 is discharged. At this time, the check valve 1504a, which is positioned opposite the pump supply hole 1501, is in close contact with the wall surface surrounding the pump supply hole 1501, so backflow of ink from the pump chamber 1503 to the pump supply hole 1501 is suppressed.

[0093] Conversely, if the diaphragm 1506 is displaced in a direction that expands the pump chamber 1503, the pressure in the pump chamber 1503 decreases. As a result, the check valve 1504a, which is positioned opposite the pump supply hole 1501, opens, and ink is supplied to the pump chamber 1503. At this time, the check valve 1504b, which is positioned at the pump discharge hole 1502, comes into close contact with the surrounding wall surface of the opening formed in the pump housing 1505, closing the opening. Therefore, backflow of ink from the pump discharge hole 1502 to the pump chamber 1503 is suppressed.

[0094] In the circulating pump 1500, the diaphragm 1506 deforms, changing the pressure inside the pump chamber 1503, thereby drawing in and discharging ink. However, if bubbles are mixed into the pump chamber 1503, even if the diaphragm 1506 is displaced, the expansion and contraction of the bubbles reduces the pressure change inside the pump chamber 1503, resulting in a decrease in the amount of liquid delivered. Therefore, the pump chamber 1503 is positioned parallel to gravity to make it easier for bubbles mixed into the pump chamber 1503 to collect at the top of the pump chamber 1503, and the pump discharge hole 1502 is positioned above the center of the pump chamber 1503. This improves the efficiency of bubble discharge from the pump and stabilizes the flow rate.

[0095] <Ink flow within the liquid ejection head> Figure 19 is a diagram illustrating the flow of ink within the liquid ejection head. The circulation of ink within the liquid ejection head 1000 will be explained with reference to Figure 19. In order to more clearly explain the ink circulation path, the relative positions of each component (first pressure adjustment means 1120, second pressure adjustment means 1150, circulation pump 1500, etc.) in Figure 19 have been simplified. Therefore, the relative positions of each component differ from those in Figure 27, which will be described later. Figure 19(a) schematically shows the flow of ink when a recording operation is performed, in which ink is ejected from the ejection port 1013 to record. The arrows in the figure indicate the flow of ink. In this embodiment, both the external pump 1021 and the circulation pump 1500 start to drive when a recording operation is performed. Note that the external pump 1021 and the circulation pump 1500 may be driven regardless of the recording operation. Also, the external pump 1021 and the circulation pump 1500 do not have to be driven in conjunction, but may be driven separately and independently.

[0096] During recording, the circulation pump 1500 is ON (operating), and the ink flowing out from the first pressure control chamber 1122 flows into the supply channel 1130 and the bypass channel 1160. The ink that flows into the supply channel 1130 passes through the discharge module 1300, then flows into the recovery channel 1140, and is subsequently supplied to the second pressure control chamber 1152.

[0097] Meanwhile, the ink that flows from the first pressure control chamber 1122 into the bypass channel 1160 flows into the second pressure control chamber 1152 via the second valve chamber 1151. The ink that flows into the second pressure control chamber 1152 passes through the pump inlet channel 1170, the circulation pump 1500, and the pump outlet channel 1180, and then flows back into the first pressure control chamber 1122. At this time, the control pressure by the first valve chamber 1121 is set higher than the control pressure of the first pressure control chamber 1122, based on the relationship in Equation 2 described above. Therefore, the ink in the first pressure control chamber 1122 does not flow into the first valve chamber 1121 but is supplied again to the discharge module 1300 via the supply channel 1130. The ink that flows into the ejection module 1300 flows through the recovery channel 1140, the second pressure control chamber 1152, the pump inlet channel 1170, the circulation pump 1500, and the pump outlet channel 1180, and then flows back into the first pressure control chamber 1122. In this way, ink circulation is completed within the liquid ejection head 1000.

[0098] In the ink circulation described above, the amount (flow rate) of ink circulating in the ejection module 1300 is determined by the differential pressure of the control pressures in the first pressure control chamber 1122 and the second pressure control chamber 1152. This differential pressure is set to a circulation amount that can suppress the thickening of the ink near the ejection port in the ejection module 1300. In addition, the amount of ink consumed by recording is supplied from the ink tank 2 to the first pressure control chamber 1122 via the filter 1110 and the first valve chamber 1121. 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 1122 also decreases. As the amount of ink in the first pressure control chamber 1122 decreases, the internal volume of the first pressure control chamber 1122 decreases. As the internal volume of the first pressure control chamber 1122 decreases, the communication port 1191A opens, and ink is supplied from the first valve chamber 1121 to the first pressure control chamber 1122. As this supplied ink passes from the first valve chamber 1121 to the communication port 1191A, a pressure loss occurs, and upon entering the first pressure control chamber 1122, the positive pressure ink switches to a negative pressure state. As ink flows from the first valve chamber 1121 into the first pressure control chamber 1122, the pressure inside the first pressure control chamber increases, increasing its internal volume, and the communication port 1191A closes. In this way, the communication port 1191A repeatedly switches between open and closed states depending on the ink consumption. When no ink is consumed, the communication port 1191A remains closed.

[0099] Figure 19(b) schematically shows the ink flow immediately after the recording operation is completed and the circulation pump 1500 is turned OFF (stopped). At the time the recording operation is completed and the circulation pump 1500 is turned OFF, the pressure in the first pressure control chamber 1122 and the pressure in the second pressure control chamber 1152 are both at the control pressure during the recording operation. Therefore, ink movement occurs as shown in Figure 19(b) in accordance with the pressure difference between the pressure in the first pressure control chamber 1122 and the pressure in the second pressure control chamber 1152. Specifically, ink continues to flow from the first pressure control chamber 1122 to the discharge module 1300 via the supply channel 1130, and then through the recovery channel 1140 to the second pressure control chamber 1152. In addition, ink continues to flow from the first pressure control chamber 1122 to the second pressure control chamber 1152 via the bypass channel 1160 and the second valve chamber 1151.

[0100] The amount of ink that moves from the first pressure control chamber 1122 to the second pressure control chamber 1152 due to the flow of ink is supplied from the ink tank 2 to the first pressure control chamber 1122 via the filter 1110 and the first valve chamber 1121. Therefore, the volume inside the first pressure control chamber 1122 is kept constant. From the relationship in Equation 2 described above, when the volume inside the first pressure control chamber 1122 is constant, the spring force F1 of the valve spring 1200, the spring force F2 of the pressure adjustment spring 1220, the pressure receiving area S1 of the valve 190, and the pressure receiving area S2 of the pressure plate 1210 are kept constant. Therefore, the pressure in the first pressure control chamber 1122 is determined according to the change in the pressure (gauge pressure) P1 in the first valve chamber 1121. Thus, if there is no change in the pressure P1 in the first valve chamber 1121, the pressure P2 in the first pressure control chamber 1122 is kept at the same pressure as the control pressure during recording.

[0101] On the other hand, the pressure in the second pressure control chamber 1152 changes over time in accordance with the change in volume due to the inflow of ink from the first pressure control chamber 1122. Specifically, from the state shown in Figure 19(b) until the communication port 1191 closes and the second valve chamber 1151 and the second pressure control chamber 1152 become disconnected, as shown in Figure 19(c), the pressure in the second pressure control chamber 1152 changes according to Equation 2. After that, the pressure plate 1210 and the valve shaft 1190a become non-contacting, and the communication port 1191 closes. Then, as shown in Figure 19(d), ink flows from the recovery channel 1140 into the second pressure control chamber 1152. This inflow of ink displaces the pressure plate 1210 and the flexible member 1230, and the pressure in the second pressure control chamber 1152 changes according to Equation 4 until the internal volume of the second pressure control chamber 1152 reaches its maximum. In other words, it rises.

[0102] Furthermore, in the state shown in Figure 19(c), no ink flow occurs from the first pressure control chamber 1122 through the bypass channel 1160 and the second valve chamber 1151 to the second pressure control chamber 1152. Therefore, only the flow of ink from the first pressure control chamber 1122 to the second pressure control chamber 1152 occurs, after it has been supplied to the discharge module 1300 via the supply channel 1130 and then through the recovery channel 1140. As mentioned above, the movement of ink from the first pressure control chamber 1122 to the second pressure control chamber 1152 occurs in accordance with the pressure difference between the pressure in the first pressure control chamber 1122 and the pressure in the second pressure control chamber 1152. For this reason, when the pressure in the second pressure control chamber 1152 becomes equal to the pressure in the first pressure control chamber 1122, the movement of ink stops.

[0103] Furthermore, when the pressure in the second pressure control chamber 1152 becomes equal to the pressure in the first pressure control chamber 1122, the second pressure control chamber 1152 expands to the state shown in Figure 19(d). When the second pressure control chamber 1152 expands as shown in Figure 19(d), a storage section capable of storing ink is formed in the second pressure control chamber 1152. The time from stopping the circulation pump 1500 to transitioning to the state shown in Figure 19(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 1500 is driven from the state shown in Figure 19(d) with ink stored in the storage section, the ink in the storage section is supplied to the first pressure control chamber 1122 by the circulation pump 1500. As a result, as shown in Figure 19(e), the amount of ink in the first pressure control chamber 1122 increases, and the flexible member 1230 and the pressure plate 1210 are displaced in the expansion direction. Then, as the circulation pump 1500 continues to operate, the conditions within the circulation path will change, as shown in Figure 19(a).

[0104] In the above explanation, Figure 19(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 19(a) to (e) will occur in response to the driving and stopping of the circulation pump 1500.

[0105] As mentioned above, in this embodiment, the communication port 1191B in the second pressure adjustment means 1150 is shown as being open when the circulation pump 1500 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 1191B in the second pressure adjustment means 1150 is closed even when the circulation pump 1500 is driven and ink is circulated. The role of the bypass passage 1160 will be explained in detail below.

[0106] The bypass channel 1160 connecting the first pressure adjustment means 1120 and the second pressure adjustment means 1150 is provided to prevent the discharge module 1300 from being affected, for example, when the negative pressure generated in the circulation path becomes stronger than a predetermined value. The bypass channel 1160 is also provided to supply ink to the pressure chamber 1012 from both sides of the supply channel 1130 and the recovery channel 1140.

[0107] First, we will explain an example in which a bypass channel 1160 is provided to prevent the negative pressure from affecting the discharge module 1300 when the negative pressure 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 1500, which is driven at a constant drive amount, increases, and the flow rate through the discharge module 1300 increases. On the other hand, since the discharge module 1300 is kept at a constant temperature by a temperature control mechanism (not shown), the viscosity of the ink in the discharge module 1300 is kept constant even if the ambient temperature changes. As the flow rate of the ink flowing through the discharge module 1300 increases while the viscosity of the ink in the discharge module 1300 does not change, the negative pressure in the discharge module 1300 increases due to flow resistance. In this way, if the negative pressure in the discharge module 1300 exceeds a predetermined value, the meniscus of the discharge port 1013 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 1012 may exceed a predetermined value, potentially affecting the discharge.

[0108] Therefore, in this embodiment, a bypass channel 1160 is formed within the circulation path. By providing the bypass channel 1160, ink flows through the bypass channel 1160 when the negative pressure exceeds a predetermined value, thus maintaining a constant pressure in the discharge module 1300. Accordingly, for example, the communication port 1191B in the second pressure adjustment means 1150 may be configured with a control pressure that maintains a closed state even when the circulation pump 1500 is running. Furthermore, the control pressure in the second pressure adjustment means may be set so that the communication port 1191 in the second pressure adjustment means 1150 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 pump flow rate caused by viscosity changes such as environmental changes, or as long as a predetermined negative pressure is maintained, the communication port 1191B may be in a closed state when the circulation pump 1500 is running.

[0109] <Discharge Unit Configuration> Figure 20 is a schematic diagram showing the circulation path for one color of ink in the ejection unit 1003 of this embodiment. Figure 20(a) is an exploded perspective view of the ejection unit 1003 as seen from the first support member 1004 side, and Figure 20(b) is an exploded perspective view of the ejection unit 1003 as seen from the ejection module 1300 side. The arrows labeled IN and OUT in the figures indicate the flow of ink, and although only the flow for one color is explained, the flow for other colors is similar. Also, the second support member and electrical wiring member are omitted from Figure 20, and are also omitted in the following explanation of the ejection unit configuration. The ejection module 1300 comprises an ejection element substrate 1340 and an opening plate 1330. Figure 21 shows the opening plate 1330, and Figure 22 shows the ejection element substrate 1340.

[0110] Ink is supplied to the discharge unit 1003 from the circulation unit 200 via a joint member (not shown). The path of the ink from when it passes through the joint member back to the joint member will be described below.

[0111] The ejection module 1300 comprises an ejection element substrate 1340, which is a silicon substrate 1310, an opening plate 1330, and an ejection port forming member 1320. The ejection element substrate 1340, the opening plate 1330, and the ejection port forming member 1320 are joined together by overlapping so that the flow paths of each ink are in communication, forming the ejection module 1300, which is supported by the first support member 1004. The ejection module 1300 being supported by the first support member 1004 forms the ejection unit 1003. The ejection element substrate 1340 is equipped with an ejection port forming member 1320, which is equipped with multiple rows of ejection ports 1013 arranged in a row, and ejects a portion of the ink supplied through the ink flow paths in the ejection module 1300 from the ejection ports 1013. The ink that is not ejected is recovered through the ink flow paths in the ejection module 1300.

[0112] As shown in Figures 20 and 21, the opening plate 1330 is provided with a plurality of arranged ink supply ports 1311 and a plurality of arranged ink recovery ports 1312. As shown in Figures 22 and 23, the ejection element substrate 1340 is provided with a plurality of arranged supply connection channels 1323 and a plurality of arranged recovery connection channels 1324. Furthermore, the ejection element substrate 1340 is provided with a common supply channel 1018 that communicates with the plurality of supply connection channels 1323 and a common recovery channel 1019 that communicates with the plurality of recovery connection channels 1324. The ink channels within the ejection unit 1003 are formed by connecting the ink supply channels 1048 and ink recovery channels 1049 provided in the first support member 1004 with the channels provided in the ejection module 1300. The support member supply port 1211 is a cross-sectional opening that forms the ink supply channel 1048, and the support member recovery port 1212 is a cross-sectional opening that forms the ink recovery channel 1049.

[0113] The ink supplied to the ejection unit 1003 is supplied from the circulation unit 200 side to the ink supply channel 1048 of the first support member 1004. The ink that flows through the support member supply port 1211 in the ink supply channel 1048 is supplied to the common supply channel 1018 of the ejection element substrate 1340 via the ink supply channel 1048 and the ink supply port 1311 of the opening plate 1330, and enters the supply connection channel 1323. This is the end of the supply side channel. After that, the ink flows through the pressure chamber 1012 of the ejection port forming member 1320 to the recovery connection channel 1324 of the recovery side channel. Details of the ink flow in the pressure chamber 1012 will be described later.

[0114] In the recovery channel, ink that enters the recovery connection channel 1324 flows into the common recovery channel 1019. Subsequently, the ink flows from the common recovery channel 1019 through the ink recovery port 1312 of the opening plate 1330 to the ink recovery channel 1049 of the first support member 1004, and is recovered to the circulation unit 200 via the support member recovery port 1212.

[0115] The area of ​​the opening plate 1330 that does not have an ink supply port 1311 or an ink recovery port 1312 corresponds to the area of ​​the first support member 1004 that separates the support member supply port 1211 and the support member recovery port 1212. Furthermore, the first support member 1004 also does not have an opening in this area. Such an area is used as an adhesive area when bonding the discharge module 1300 and the first support member 1004.

[0116] In Figure 21, the opening plate 1330 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. In Figure 22, the ejection element substrate 1340 has a common supply channel 1018 that communicates with multiple supply connection channels 1323 arranged in the Y direction, and a common recovery channel 1019 that communicates with multiple recovery connection channels 1324 arranged in the Y direction, arranged alternately in the X direction. The common supply channels 1018 and common recovery channels 1019 are separated by ink type, and the number of common supply channels 1018 and common recovery channels 1019 is determined according to the number of ejection port rows for each color. In addition, the supply connection channels 1323 and recovery connection channels 1324 are also arranged in a number corresponding to the number of ejection ports 1013. Furthermore, a one-to-one correspondence is not necessarily required; a single supply connection channel 1323 and a recovery connection channel 1324 may correspond to multiple discharge ports 1013.

[0117] The opening plate 1330 and the ejection element substrate 1340 are joined together so that the flow paths of each ink are in communication, forming an ejection module 1300, which is supported by the first support member 1004. This creates an ink flow path with the supply flow path and recovery flow path described above.

[0118] Figures 23(a) to (c) are cross-sectional views showing the ink flow in different parts of the ejection unit 1003. Figure 23(a) is the cross-section shown at XXIIIa-XXIIIa in Figure 20(a), showing the cross-section of the part of the ejection unit 1003 where the ink supply channel 1048 and the ink supply port 1311 are in communication. Figure 23(b) is the cross-section shown at XXIIIb-XXIIIb in Figure 20(a), showing the cross-section of the part of the ejection unit 1003 where the ink recovery channel 1049 and the ink recovery port 1312 are in communication. Figure 23(c) is the cross-section shown at XXIIIc-XXIIIc in Figure 20(a), showing the cross-section of the part where the ink supply port 1311 and the ink recovery port 1312 are not in communication with the channel of the first support member 1004.

[0119] In the ink supply channel, as shown in Figure 23(a), ink is supplied from the overlapping and communicating portion of the ink supply channel 1048 of the first support member 1004 and the ink supply port 1311 of the opening plate 1330. In the ink recovery channel, as shown in Figure 23(b), ink is recovered from the overlapping and communicating portion of the ink recovery channel 1049 of the first support member 1004 and the ink recovery port 1312 of the opening plate 1330. Also, as shown in Figure 23(c), in the ejection unit 1003, there are areas where the opening plate 1330 does not have an opening. In such areas, ink is not supplied or recovered between the ejection element substrate 1340 and the first support member 1004. Ink is supplied in the area where the ink supply port 1311 is provided, as shown in Figure 23(a), and ink is recovered in the area where the ink recovery port 1312 is provided, as shown in Figure 23(b). In this embodiment, a configuration using an opening plate 1330 has been described as an example, but a configuration without an opening plate 1330 is also possible. For example, a configuration in which channels corresponding to the ink supply channel 1048 and the ink recovery channel 1049 are formed in the first support member 1004, and the ejection element substrate 1340 is joined to the first support member 1004 is also possible.

[0120] Figures 24(a) and (b) are cross-sectional views showing the vicinity of the discharge port 1013 in the discharge module 1300. The thick arrows shown within the common supply channel 1018 and common recovery channel 1019 in Figure 24 indicate the oscillation of the ink in a configuration using a serial-type liquid discharge device 2000. The ink supplied to the pressure chamber 1012 via the common supply channel 1018 and the supply connection channel 1323 is discharged from the discharge port 1013 when the discharge element 1015 is driven. If the discharge element 1015 is not driven, the ink is recovered from the pressure chamber 1012 through the recovery connection channel 1324, which is a recovery channel, to the common recovery channel 1019.

[0121] In a configuration using a serial-type liquid ejection device 2000, 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 within the ink flow path caused by the main scanning of the liquid ejection head 1000. Specifically, the effect of the oscillation of the ink within the ink flow path may manifest as differences in the amount of ink ejected or deviations in the ejection direction.

[0122] Therefore, in this embodiment, the common supply channel 1018 and the common recovery channel 1019 both extend in the Y direction in the cross-section shown in Figure 24, 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 1018 and the common recovery channel 1019 in the main scanning direction. Reducing the width of each channel in the common supply channel 1018 and the common recovery channel 1019 in the main scanning direction reduces the oscillation of the ink due to the inertial force (thick black arrow in the figure) acting on the ink in the common supply channel 1018 and the common recovery channel 1019 acting on the ink opposite to the main scanning direction during main scanning. This makes it possible to suppress the effect of ink oscillation on ink discharge. In addition, extending the common supply channel 1018 and the common recovery channel 1019 in the Z direction increases the cross-sectional area and reduces flow pressure loss.

[0123] As described above, by reducing the width of each channel in the common supply channel 1018 and the common recovery channel 1019 in the main scanning direction, the oscillation of ink in the common supply channel 1018 and the common recovery channel 1019 during main scanning is reduced, but the oscillation is not eliminated. Therefore, in order to suppress the difference in discharge between different ink types that may still occur even with reduced oscillation, in this embodiment, the common supply channel 1018 and the common recovery channel 1019 are configured to be positioned in a position that overlaps with respect to the X direction.

[0124] As described above, in this embodiment, the supply connection channel 1323 and the recovery connection channel 1324 are provided corresponding to the discharge port 1013, and the supply connection channel 1323 and the recovery connection channel 1324 are arranged side by side in the X direction with the discharge port 1013 in between. Therefore, there is a portion where the common supply channel 1018 and the common recovery channel 1019 do not overlap in the X direction, and if the correspondence between the supply connection channel 1323 and the recovery connection channel 1324 in the X direction is disrupted, it will affect the flow and discharge of ink in the X direction in the pressure chamber 1012. If the effect of ink oscillation is added to this, it may further affect the discharge of ink at each discharge port.

[0125] Therefore, the common supply channel 1018 and the common recovery channel 1019 are positioned to overlap with respect to the X direction. As a result, the ink oscillation during the main scan in the common supply channel 1018 and the common recovery channel 1019 is almost the same at any position in the Y direction where the discharge ports 1013 are arranged. Consequently, the pressure difference between the common supply channel 1018 side and the common recovery channel 1019 side that occurs in the pressure chamber 1012 does not fluctuate significantly, and stable discharge can be achieved.

[0126] 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 1018 and the common recovery flow path 1019 are separate flow paths. The supply connection flow path 1323 and the pressure chamber 1012 are in communication, and the pressure chamber 1012 and the recovery connection flow path 1324 are in communication, and ink is ejected from the discharge port 1013 of the pressure chamber 1012. In other words, the pressure chamber 1012, which is the path connecting the supply connection flow path 1323 and the recovery connection flow path 1324, is configured to have a discharge port 1013. Therefore, an ink flow occurs in the pressure chamber 1012 from the supply connection flow path 1323 side to the recovery connection flow path 1324 side, and the ink in the pressure chamber 12 is efficiently circulated. By efficiently circulating the ink in the pressure chamber 1012, the ink in the pressure chamber 1012, which is susceptible to the effects of ink evaporation from the discharge port 1013, can be kept in a fresh state.

[0127] Furthermore, since the two common supply channel 1018 and common recovery channel 1019 are in communication with the pressure chamber 1012, 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.

[0128] Furthermore, the common supply channel 1018 and the common recovery channel 1019 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.

[0129] Figure 25 shows an ejection element substrate 1340 as a comparative example. Note that the supply connection channel 1323 and the recovery connection channel 1324 are omitted in Figure 25. Ink that has received thermal energy from the ejection element 1015 in the pressure chamber 1012 flows into the common recovery channel 1019, so ink that is relatively hotter flows in the common recovery channel 1019 compared to the ink temperature in the common supply channel 1018. In this case, as shown in part α enclosed by the dashed line in Figure 25, there is a part of the ejection element substrate 1340 in the X direction where only the common recovery channel 1019 exists. In this case, the temperature rises locally in that part, causing temperature unevenness within the ejection module 1300, which may affect ejection.

[0130] Ink at a relatively lower temperature flows through the common supply channel 1018 compared to the common recovery channel 1019. Therefore, if the common supply channel 1018 and the common recovery channel 1019 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 1018 and the common recovery channel 1019 are adjacent to each other, overlapping in the X direction, with approximately the same length.

[0131] Figures 26(a) and (b) show the flow path configuration of the liquid ejection head 1000, which corresponds to three ink colors: cyan (C), magenta (M), and yellow (Y). As shown in Figure 26(a), the liquid ejection head 1000 is provided with separate circulation channels for each ink type. The pressure chamber 1012 is located along the X direction, which is the main scanning direction of the liquid ejection head 1000. Also, as shown in Figure 26(b), the common supply channel 1018 and the common recovery channel 1019 are located along the row of ejection ports 1013, and extend in the Y direction so as to sandwich the row of ejection ports between the common supply channel 1018 and the common recovery channel 1019.

[0132] <Connection between the main unit and the liquid dispensing head> Figure 27 is a schematic diagram showing in more detail the connection state between the ink tank 2 and external pump 1021 and the liquid ejection head 1000, as well as the arrangement of the circulation pump and other components, provided in the main body of the liquid ejection device 2000 of this embodiment. The liquid ejection device 2000 in this embodiment is configured to allow for easy replacement of only the liquid ejection head 1000 in the event of a malfunction in the liquid ejection head 1000. Specifically, it has a liquid connection part 1700 that allows for easy connection and disconnection between the ink supply tube 1059 connected to the external pump 1021 and the liquid ejection head 1000. This makes it possible to easily attach and detach only the liquid ejection head 1000 from the liquid ejection device 2000.

[0133] As shown in Figure 27, the liquid connection section 1700 has a liquid connector insertion port 1053a protruding from the head housing 1053 of the liquid discharge head 1000, and a cylindrical liquid connector 1059a into which the liquid connector insertion port 1053a can be inserted. The liquid connector insertion port 1053a is fluidically connected to an ink supply channel formed inside the liquid discharge head 1000 and is connected to the first pressure adjustment means 1120 via the aforementioned filter 1110. The liquid connector 1059a is provided at the tip of an ink supply tube 1059 connected to an external pump 1021 that pressurizes and supplies ink from the ink tank 2 to the liquid discharge head 1000.

[0134] As described above, the liquid discharge head 1000 shown in Figure 27 can be easily attached, detached, and replaced by the liquid connection part 1700. However, if the sealing performance between the liquid connector insertion port 1053a and the liquid connector 1059a deteriorates, there is a risk that the ink supplied under pressure by the external pump 1021 may leak from the liquid connection part 1700. If the leaked ink adheres to the circulation pump 1500, etc., it may cause a malfunction in the electrical system. Therefore, in this embodiment, the circulation pump, etc. are arranged as follows.

[0135] <Placement of circulation pumps, etc.> As shown in Figure 27, in this embodiment, in order to prevent ink leaking from the liquid connection part 1700 from adhering to the circulation pump 1500, the circulation pump 1500 is positioned above the liquid connection part 1700 in the direction of gravity. In other words, the circulation pump 1500 is positioned above the liquid connector insertion port 1053a, which is the liquid inlet of the liquid discharge head 1000, in the direction of gravity. Furthermore, the circulation pump 1500 is positioned so as not to be in contact with the components constituting the liquid connection part 1700. As a result, even if ink leaks from the liquid connection part 1700, the ink will flow horizontally, which is the opening direction of the liquid connector 1059a, or downward in the direction of gravity, thus preventing the ink from reaching the circulation pump 1500, which is located above in the direction of gravity. In addition, because the circulation pump 1500 is positioned away from the liquid connection part 1700, the possibility of ink traveling along the components and reaching the circulation pump 1500 is also reduced.

[0136] Furthermore, an electrical connection section 1515, which electrically connects the circulation pump 1500 and the electrical contact substrate 1006 via a flexible wiring member 1514, is provided above the liquid connection section 1700 in the direction of gravity. This reduces the possibility of electrical problems caused by ink originating from the liquid connection section 1700.

[0137] Furthermore, in this embodiment, since the wall portion 1052b of the head housing 1053 is provided, even if ink is ejected from the opening 1059b of the liquid connection portion 1700, the ink can be blocked, reducing the possibility of it reaching the circulation pump 1500 or the electrical connection portion 1515.

[0138] This embodiment includes the following configuration.

[0139] (Composition 1) A recording element substrate having a pressure chamber with a discharge port formed therein, and discharging liquid from the discharge port, A first supply channel is provided on the recording element substrate and is in communication with the pressure chamber, A first recovery channel is provided on the recording element substrate and is in communication with the pressure chamber, A circulation pump that generates a pressure difference between the first supply channel and the first recovery channel so as to supply liquid from the first supply channel to the pressure chamber and recover the liquid from the pressure chamber from the first recovery channel, A second supply channel connecting the first supply channel and the circulation pump, A liquid dispensing head equipped with, The liquid discharge head is characterized in that the second supply channel has a vertical cross-sectional area in the liquid circulation direction that is at least twice the vertical cross-sectional area in the liquid circulation direction of the first supply channel, is inclined with respect to the direction of gravity, and has an inner wall of the channel whose normal vector component has a component in the direction of gravity.

[0140] (Configuration 2) The system further comprises a second recovery channel connecting the first recovery channel and the circulation pump, The liquid discharge head according to configuration 1, characterized in that the second recovery channel has a vertical cross-sectional area in the liquid circulation direction that is at least twice the vertical cross-sectional area in the liquid circulation direction of the first recovery channel, is inclined with respect to the direction of gravity, and has an inner wall of the channel whose component of the normal vector has a component in the direction of gravity.

[0141] (Composition 3) The recording element substrate has a plurality of pressure chambers, The liquid discharge head according to configuration 1 or 2, characterized in that the second supply channel has a vertical cross-sectional area in the liquid circulation direction that is at least twice the total area of ​​the vertical cross-sectional areas in the liquid circulation direction of the plurality of first supply channels.

[0142] (Composition 4) The liquid discharge head according to configuration 2, characterized in that the second recovery channel has a vertical cross-sectional area in the liquid circulation direction that is at least twice the total area of ​​the vertical cross-sectional areas in the liquid circulation direction of the plurality of first recovery channels.

[0143] (Composition 5) A liquid discharge head according to any one of configurations 1 to 4, characterized in that the second supply channel is provided with a first bubble storage section having a channel inner wall that has a vertical cross-sectional area in the liquid circulation direction that is at least twice the minimum vertical cross-sectional area in the liquid circulation direction of the second supply channel, is inclined with respect to the direction of gravity, and whose component of the normal vector has a component in the direction of gravity.

[0144] (Composition 6) The liquid discharge head according to configuration 2 or 4, characterized in that the second recovery channel is provided with a second bubble storage section having a channel inner wall that has a vertical cross-sectional area in the liquid circulation direction that is at least twice the minimum vertical cross-sectional area in the liquid circulation direction of the second recovery channel, is inclined with respect to the direction of gravity, and whose component of the normal vector has a component in the direction of gravity.

[0145] (Composition 7) A liquid discharge head according to any one of configurations 1 to 6, characterized in that the angle between the normal vector of the inclined inner wall of the second supply channel and the gravity direction vector is 15 degrees or more.

[0146] (Composition 8) The liquid discharge head according to configuration 2 or 4, characterized in that the angle between the normal vector of the inclined inner wall of the second recovery channel and the gravity direction vector is 15 degrees or more.

[0147] (Composition 9) The device further comprises a row of discharge ports arranged in a plurality of the aforementioned discharge ports, The second supply channel has a first connection section that branches into at least two or more and connects to the first supply channel, The second recovery channel has a second connection section that branches to at least one or more and connects to the first recovery channel, The liquid discharge head according to configuration 2 or 4, characterized in that the first connection portion and the second connection portion are arranged alternately along the row of discharge ports.

[0148] (Composition 10) A recording element substrate having a pressure chamber with a discharge port formed therein, and discharging liquid from the discharge port, A first supply channel is provided on the recording element substrate and is in communication with the pressure chamber, A first recovery channel is provided on the recording element substrate and is in communication with the pressure chamber, A circulation pump that generates a pressure difference between the first supply channel and the first recovery channel so as to supply liquid from the first supply channel to the pressure chamber and recover the liquid from the pressure chamber from the first recovery channel, A second recovery channel connecting the first recovery channel and the circulation pump, A liquid dispensing head equipped with, The liquid discharge head is characterized in that the second recovery channel has a vertical cross-sectional area in the liquid circulation direction that is at least twice the vertical cross-sectional area in the liquid circulation direction of the first recovery channel, is inclined with respect to the direction of gravity, and has an inner wall of the channel whose normal vector component has a component in the direction of gravity.

[0149] (Composition 11) A recording element substrate having a pressure chamber with a discharge port formed therein, and discharging liquid from the discharge port, A first supply channel is provided on the recording element substrate and is in communication with the pressure chamber, A first recovery channel is provided on the recording element substrate and is in communication with the pressure chamber, A circulation pump that generates a pressure difference between the first supply channel and the first recovery channel so as to supply liquid from the first supply channel to the pressure chamber and recover the liquid from the pressure chamber from the first recovery channel, A second supply channel connecting the first supply channel and the circulation pump, A liquid dispensing head equipped with, A liquid discharge head is provided with a first bubble reservoir in the second supply channel, which has a vertical cross-sectional area in the liquid circulation direction that is at least twice the minimum vertical cross-sectional area in the liquid circulation direction of the second supply channel, is inclined with respect to the direction of gravity, and has an inner wall of the channel whose component of the normal vector has a component in the direction of gravity.

[0150] (Composition 12) A recording element substrate having a pressure chamber with a discharge port formed therein, and discharging liquid from the discharge port, A first supply channel is provided on the recording element substrate and is in communication with the pressure chamber, A first recovery channel is provided on the recording element substrate and is in communication with the pressure chamber, A circulation pump that generates a pressure difference between the first supply channel and the first recovery channel so as to supply liquid from the first supply channel to the pressure chamber and recover the liquid from the pressure chamber from the first recovery channel, A second recovery channel connecting the first recovery channel and the circulation pump, A liquid dispensing head equipped with, A liquid discharge head is provided with a first bubble storage section in the second recovery channel, which has a vertical cross-sectional area in the liquid circulation direction that is at least twice the minimum vertical cross-sectional area in the liquid circulation direction of the second recovery channel, is inclined with respect to the direction of gravity, and has an inner wall of the channel whose component of the normal vector has a component in the direction of gravity.

[0151] (Composition 13) A liquid dispensing device characterized by being capable of being equipped with a liquid dispensing head described in any one of configurations 1 to 12. [Explanation of Symbols]

[0152] 102 Support member 110 Recording element substrate 113 Pressure Chamber 114 Discharge port 301 First bubble storage channel 302 Second bubble storage channel 310 First ink connection channel 320 Second ink connection channel 500 bubbles 1000 liquid dispensing heads 2000 Liquid discharge device

Claims

1. A recording element substrate having an ejection port for ejecting liquid, an ejection element for generating pressure to eject liquid from said ejection port, a plurality of pressure chambers that apply pressure generated by driving said ejection element to the liquid, a plurality of common supply flow paths communicating with said plurality of pressure chambers, and a plurality of common recovery flow paths communicating with said plurality of pressure chambers; a circulation pump that generates a pressure difference between the common supply flow path and the common recovery flow path so as to supply liquid from the common supply flow path to the plurality of pressure chambers and recover liquid from the plurality of pressure chambers to the common recovery flow path; a support member for supporting the recording element substrate, the support member having a distribution flow path formed therein for distributing liquid to the plurality of common supply flow paths; A liquid ejection head comprising: a common supply flow path opening through which the liquid distributed from the distribution flow paths enters the common supply flow path is formed in the recording element substrate; The support member has a distribution flow path opening formed on the opposite side of the distribution flow path from the common supply flow path opening side, an opening area of ​​the distribution flow path opening is larger than an opening area of ​​the common supply flow path opening; A liquid ejection head, wherein the distribution flow path has an inner wall that is inclined with respect to the direction of gravity when the liquid ejection head is in a used state.

2. A liquid ejection head as described in Claim 1, wherein the opening area of ​​the distribution flow path opening is at least twice the opening area of ​​the common supply flow path opening.

3. A liquid ejection head as described in claim 1, wherein the angle formed by the normal vector of the inner wall of the flow path and the gravity direction vector is 15 degrees or more.

4. A liquid ejection head as described in Claim 1, wherein the distribution flow path is formed in multiple parts in the support member.

5. A liquid ejection head as described in Claim 4, wherein the multiple distribution flow paths are arranged in parallel along the direction in which the common supply flow path extends.

6. A liquid ejection head as described in claim 5, having a first bubble storage flow path that distributes liquid to the multiple distribution flow paths.

7. A liquid ejection head as described in Claim 6, wherein the cross-sectional area of ​​the first bubble storage flow path in the ink circulation direction is 20 times or more the opening area of ​​the distribution flow path opening.

8. A liquid ejection head as described in Claim 1, wherein the support member has a collection flow path formed therein that collects liquid from the multiple common recovery flow paths.

9. The recording element substrate is formed with a common recovery flow path opening for discharging the liquid collected in the collecting flow path from the common recovery flow path, The support member has a collecting flow path opening formed on the opposite side of the collecting flow path from the common recovery flow path opening side, The liquid ejection head according to claim 8 , wherein the opening area of ​​the collection flow path opening is larger than the opening area of ​​the common recovery flow path opening.

10. A liquid ejection head as described in Claim 9, wherein the collection flow path is formed in multiple parts in the support member.

11. A liquid ejection head as described in Claim 10, wherein the multiple collection flow paths are arranged in parallel along the direction in which the common recovery flow path extends.

12. A liquid ejection head as described in Claim 11, further comprising a second bubble storage flow path that collects liquid from the multiple collection flow paths.

13. A recording element substrate having an ejection port for ejecting liquid, an ejection element for generating pressure to eject liquid from said ejection port, a plurality of pressure chambers that act on the liquid with pressure generated by driving said ejection element, a plurality of common supply flow paths communicating with said plurality of pressure chambers, and a plurality of common recovery flow paths communicating with said plurality of pressure chambers; a circulation pump that generates a pressure difference between the common supply flow path and the common recovery flow path so as to supply liquid from the common supply flow path to the plurality of pressure chambers and recover liquid from the plurality of pressure chambers to the common recovery flow path; a support member for supporting the recording element substrate, the support member having a plurality of distribution flow paths formed therein for distributing liquid to the plurality of common supply flow paths; a first bubble storage channel that distributes liquid to the plurality of distribution channels; A liquid ejection head comprising: the distribution channel includes a distribution channel opening connected to the first bubble storage channel, A liquid ejection head, characterized in that the cross-sectional area of ​​the first bubble storage channel in the ink circulation direction is larger than the opening area of ​​the distribution channel opening.

14. A liquid ejection head as described in Claim 13, wherein the cross-sectional area of ​​the first bubble storage flow path in the ink circulation direction is at least twice the opening area of ​​the distribution flow path opening.

15. A liquid ejection head as described in Claim 14, wherein the cross-sectional area of ​​the first bubble storage flow path in the ink circulation direction is 20 times or more the opening area of ​​the distribution flow path opening.

16. A liquid ejection head as described in Claim 13, wherein the support member has a plurality of collection flow paths formed therein that collect liquid from the plurality of common recovery flow paths.

17. The collecting flow path is formed in plurality in the support member, The liquid ejection head according to claim 16, wherein the plurality of collecting channels are arranged in parallel along the direction in which the common recovery channel extends.

18. A liquid ejection head as described in Claim 17, further comprising a second bubble storage flow path that collects liquid from the multiple collection flow paths.

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