Liquid discharge head and liquid discharge device

Abstract

To provide a liquid discharge head and a liquid discharge device that can suppress a discharge failure.SOLUTION: Movement of a pressure plate 210 with decrease in volume of a first pressure control chamber 122 increases a flow resistance of a flow channel connected to a supply flow channel 130 via a second discharge channel 802 relative to a flow resistance of a flow channel connected to the supply flow channel 130 via a first discharge channel 801.SELECTED DRAWING: Figure 22

Description

[Technical field]

[0001] The present disclosure relates to a liquid ejection head and a liquid ejection apparatus including the liquid ejection head. [Background technology]

[0002] A circulation type liquid ejection device is known that circulates the liquid between the liquid ejection head and the liquid storage section to suppress the discharge of air bubbles in the flow path and the thickening of the ink near the ejection port. Among circulation type liquid ejection devices, some use a pump on the main body side external to the liquid ejection head to circulate the liquid between the liquid ejection head and the main body, while others use a pump inside the liquid ejection head to circulate the liquid inside the liquid ejection head.

[0003] Patent Document 1 discloses a liquid ejection device that circulates ink in a liquid ejection head by mounting a piezoelectric circulation pump in the liquid ejection head. In the configuration of Patent Document 1, ink supplied from the circulation pump to a pressure control mechanism is supplied to a pressure chamber via an ink supply flow path, and ink that is not ejected is collected to the circulation pump via an ink collection flow path. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2014-195932 A Summary of the Invention [Problem to be solved by the invention]

[0005] A circulation type liquid ejection head such as that of Patent Document 1 has an increased number of ink flow paths, such as an ink recovery flow path, compared to a non-circulation type liquid ejection head, and therefore the ink storage volume in the liquid ejection head is likely to be large. In Patent Document 1, the ink supply tube that supplies ink from the ink filling chamber located upstream of the pressure chamber to the pressure chamber is disposed at the bottom of the ink filling chamber. If air bubbles are generated in the ink filling chamber, the air bubbles will accumulate at the top of the ink filling chamber due to buoyancy. In a configuration in which the ink supply tube that discharges air from the ink filling chamber is disposed at the bottom of the ink filling chamber as in Patent Document 1, it may be difficult to discharge air bubbles generated in the ink filling chamber.

[0006] In particular, when the ink storage volume in the liquid ejection head becomes large, the amount of remaining air bubbles in the liquid ejection head tends to increase. In a configuration in which the amount of remaining air bubbles tends to increase and it is difficult to expel the air bubbles, the remaining air bubbles may end up flowing into the pressure chamber, causing ejection defects.

[0007] Therefore, the present disclosure provides a liquid ejection head and a liquid ejection apparatus that can suppress the occurrence of ejection defects. [Means for solving the problem]

[0008] Therefore, the liquid ejection head of the present disclosure is a liquid ejection head comprising: an ejection port for ejecting liquid, an ejection element for generating pressure for ejecting liquid from the ejection port, a pressure chamber in which the ejection element is provided and connected to the ejection port, and a first pressure adjustment means capable of changing its volume according to the pressure of the liquid and adjusting the pressure of the liquid, and further comprising: a first flow path connecting the first pressure adjustment means and the pressure chamber, a first exhaust port provided at an upper part of the first pressure adjustment means in a vertical direction, a first exhaust flow path connecting the first exhaust port and the first flow path, a second exhaust port provided in the first pressure adjustment means, and a second exhaust flow path connecting the second exhaust port and the first flow path, and is characterized in that when the volume of the first pressure adjustment means decreases, the liquid ejection head comprises flow resistance increasing means for increasing the flow resistance in the flow path that flows liquid from the first pressure adjustment means through the second exhaust port and the second exhaust flow path to the first flow path, relative to the flow resistance in the flow path that flows liquid from the first pressure adjustment means through the first exhaust port and the first exhaust flow path to the first flow path. Effect of the Invention

[0009] According to the present disclosure, it is possible to provide a liquid ejection head and a liquid ejection apparatus capable of suppressing the occurrence of ejection defects. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a diagram illustrating a liquid ejection device. [Diagram 2] FIG. 1 is an exploded perspective view of a liquid ejection head; [Diagram 3] 2A and 2B are a longitudinal section of a liquid ejection head and an enlarged cross-sectional view of an ejection module. [Figure 4] FIG. 1 is a schematic view showing the appearance of a circulation unit; [Diagram 5] FIG. [Figure 6] FIG. 2 is a block diagram showing a schematic diagram of a circulation path. [Figure 7] FIG. 4 is a cross-sectional view showing an example of a pressure adjusting means. [Figure 8] FIG. 2 is an external perspective view of a circulation pump. [Figure 9] 9 is a cross-sectional view of the circulating pump shown in FIG. 8(a) taken along line IX-IX. [Figure 10] 3A and 3B are diagrams illustrating the flow of ink in a liquid ejection head. [Figure 11] FIG. 4 is a schematic diagram showing a circulation path in the discharge unit. [Figure 12] FIG. 2 is a diagram showing an aperture plate. [Figure 13] FIG. 2 is a diagram showing a discharge element substrate. [Figure 14] 5A and 5B are cross-sectional views showing the ink flow in the ejection unit. [Figure 15] FIG. 4 is a cross-sectional view showing the vicinity of a discharge port. [Figure 16] FIG. 11 is a cross-sectional view showing a comparative example near the ejection port. [Figure 17] 11A and 11B are diagrams showing a comparative example of a discharge element substrate. [Figure 18] FIG. 2 is a diagram showing a flow path configuration of a liquid ejection head. [Figure 19] 2A and 2B are diagrams illustrating a connection state between a main body of the liquid ejection device and a liquid ejection head. [Figure 20] FIG. 4 is a diagram illustrating a backflow of ink in the vicinity of an ejection port. [Figure 21] FIG. 4 is a diagram illustrating ink supply within the ejection module. [Figure 22] FIG. 2 is a diagram illustrating a flow path configuration in a liquid ejection head. [Figure 23] FIG. 4 is a front cross-sectional view of the first pressure control chamber. [Figure 24] FIG. 2 is a diagram illustrating a flow path configuration in a liquid ejection head. [Diagram 25] 1 is a graph showing the relationship between flow resistance and distance. [Figure 26] FIG. 2 is a diagram illustrating a flow path configuration in a liquid ejection head. [Figure 27] FIG. 11 is a diagram illustrating a circulation path in a first modified example. [Figure 28] FIG. 11 is a diagram illustrating a circulation path in a first modified example. [Figure 29]FIG. 13 is a diagram illustrating a circulation path in a second modified example. [Diagram 30] FIG. 13 is a diagram illustrating a circulation path in a second modified example. [Diagram 31] FIG. 2 is a block diagram illustrating a schematic diagram of a liquid circulation path. [Diagram 32] FIG. 2 is a block diagram illustrating a schematic diagram of a liquid circulation path. [Diagram 33] FIG. 2 is a block diagram illustrating a schematic diagram of a liquid circulation path. [Diagram 34] FIG. 13 is a diagram illustrating a circulation path in a fourth modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] (First embodiment) A preferred first embodiment of the present disclosure will be described in detail below with reference to the accompanying drawings. The following embodiment does not limit the disclosed matters, and not all combinations of features described in the present embodiment are necessarily essential to the solving means of the present disclosure. The same components are given the same reference numbers. In this embodiment, an example is described in which a thermal method is adopted in which an electrothermal conversion element generates bubbles to eject liquid as an ejection element for ejecting liquid, but this is not limited to this. The present invention can also be applied to an ejection method in which a piezoelectric element (piezo) is used to eject liquid, or to a liquid ejection head in which another ejection method is adopted. Furthermore, the pump and pressure adjustment means described below are not limited to the configurations themselves described in the embodiments and drawings. In the following description, the basic configuration of the present disclosure will be described first, and then the characteristic parts of the present disclosure will be described.

[0012] <Liquid discharge device> Fig. 1 is a diagram for explaining a liquid ejection device, and is an enlarged view of a liquid ejection head of the liquid ejection device and its surroundings. First, a schematic configuration of a liquid ejection device 50 in this embodiment will be described with reference to Fig. 1. Fig. 1(a) is a perspective view that shows a liquid ejection device capable of mounting a liquid ejection head 1. The liquid ejection device 50 in this embodiment constitutes a serial type inkjet recording device that performs recording on a recording medium P by ejecting ink as a liquid while scanning the liquid ejection head 1.

[0013] The liquid ejection head 1 is mounted on a carriage 60. The carriage 60 reciprocates along a guide shaft 51 in a main scanning direction (X direction). The recording medium P is transported by transport rollers 55, 56, 57, and 58 in a sub-scanning direction (Y direction) that intersects (orthogonal in this example) the main scanning direction. In each of the figures referred to below, the Z direction indicates the vertical direction, and intersects (orthogonal in this example) the XY plane defined by the X and Y directions. The liquid ejection head 1 is configured to be removable and attachable to the carriage 60 by the user.

[0014] The liquid ejection head 1 includes a circulation unit 54 and an ejection unit 3 (see FIG. 2) described later. The specific configuration will be described later, but the ejection unit 3 is provided with a plurality of ejection ports and energy generating elements (hereinafter referred to as ejection elements) that generate ejection energy for ejecting liquid from each ejection port.

[0015] The liquid ejection device 50 is also provided with an ink tank 2, which is an ink supply source, and an external pump 21, and the ink stored in the ink tank 2 is supplied to the circulation unit 54 via an ink supply tube 59 by the driving force of the external pump 21.

[0016] The liquid ejection device 50 repeats a recording scan in which the liquid ejection head 1 mounted on the carriage 60 moves in the main scanning direction while ejecting ink to perform recording, and a transport operation in which the recording medium P is transported in the sub-scanning direction, thereby forming a predetermined image on the recording medium P. The liquid ejection head 1 in this embodiment is capable of ejecting four types of ink, namely black (K), cyan (C), magenta (M), and yellow (Y), and is capable of recording a full-color image using these inks. However, the inks that can be ejected from the liquid ejection head 1 are not limited to the above four types of ink. The present disclosure is also applicable to liquid ejection heads for ejecting other types of ink. In other words, the types and number of inks ejected from the liquid ejection head are not limited.

[0017] Furthermore, the liquid ejection device 50 is provided with a cap member (not shown) capable of covering the ejection port surface on which the ejection ports of the liquid ejection head are formed, at a position offset in the X direction from the transport path of the recording medium P. The cap member covers the ejection port surface of the liquid ejection head 1 during non-recording operations, and is used to prevent and protect the ejection ports from drying, and to suck ink from the ejection ports, etc.

[0018] 1(a) shows an example in which the liquid ejection head 1 is provided with four circulation units 54 corresponding to the four types of ink, but it is sufficient that the liquid ejection head 1 is provided with a circulation unit 54 corresponding to the type of liquid to be ejected. Also, multiple circulation units 54 may be provided for the same type of liquid. In other words, the liquid ejection head 1 can be configured to include one or more circulation units. It is also possible to have a configuration in which at least one ink is circulated rather than circulating all four types of ink.

[0019] FIG. 1B is a block diagram showing a control system of the liquid ejection device 50. The CPU 103 functions as a control means for controlling the operation of each part of the liquid ejection device 50 based on a program such as a processing procedure stored in the ROM 101. The RAM 102 is used as a work area when the CPU 103 executes processing. The CPU 103 receives image data from a host device 400 outside the liquid ejection device 50, controls the head driver 1A, and controls the driving of the ejection elements provided in the ejection unit 3. The CPU 103 also controls the drivers of various actuators provided in the liquid ejection device. For example, the CPU 103 controls a motor driver 105A of a carriage motor 105 for moving the carriage 60, a motor driver 104A of a conveying motor 104 for conveying the recording medium P, and the like. The CPU 103 also controls a pump driver 500A for driving a circulation pump 500 described later, a pump driver 21A of an external pump 21, and the like. Although FIG. 1B shows a form in which processing is performed upon receiving image data from the host device 400, processing may be performed by the liquid ejection device 50 independently of data from the host device 400.

[0020] <Basic configuration of liquid ejection head> Fig. 2 is an exploded perspective view of the liquid ejection head 1 of this embodiment. Fig. 3 is a cross-sectional view of the liquid ejection head 1 shown in Fig. 2 taken along line IIIA-IIIA. Fig. 3(a) is an overall vertical cross-sectional view of the liquid ejection head 1, and Fig. 3(b) is an enlarged view of the ejection module shown in Fig. 3(a). The basic structure of the liquid ejection head 1 of this embodiment will be described below, mainly with reference to Fig. 2 and Fig. 3, and also with reference to Fig. 1 as appropriate.

[0021] 2, the liquid ejection head 1 includes a circulation unit 54 and an ejection unit 3 for ejecting ink supplied from the circulation unit 54 onto a recording medium P. The liquid ejection head 1 in this embodiment is fixedly supported on a carriage 60 of the liquid ejection device 50 by positioning means and electrical contacts (not shown) provided on the carriage 60. The liquid ejection head 1 ejects ink while moving together with the carriage 60 in the main scanning direction (X direction) shown in FIG. 1, and performs recording on the recording medium P.

[0022] An ink supply tube 59 is provided on the external pump 21 connected to the ink tank 2 serving as the ink supply source (see FIG. 1). A liquid connector (not shown) is provided on the tip of the ink supply tube 59. When the liquid ejection head 1 is mounted on the liquid ejection device 50, the liquid connector provided on the tip of the ink supply tube 59 is airtightly connected to a liquid connector insertion port 53a, which is a liquid inlet port provided on a head housing 53 of the liquid ejection head 1. This forms an ink supply path from the ink tank 2 to the liquid ejection head 1 via the external pump 21. In this embodiment, since four types of ink are used, four sets of the ink tank 2, the external pump 21, the ink supply tube 59, and the circulation unit 54 are provided corresponding to each ink, and four ink supply paths corresponding to each ink are independently formed. In this way, the liquid ejection device 50 of this embodiment is provided with an ink supply system to which ink is supplied from the ink tank 2 provided outside the liquid ejection head 1. Note that the liquid ejection device 50 of this embodiment is not provided with an ink recovery system that recovers the ink in the liquid ejection head 1 to the ink tank 2. Therefore, the liquid ejection head 1 is provided with a liquid connector insertion port 53a for connecting an ink supply tube 59 of the ink tank 2, but is not provided with a connector insertion port for connecting a tube for recovering ink from the liquid ejection head 1 to the ink tank 2. A liquid connector insertion port 53a is provided for each ink.

[0023] 3, 54B indicates a circulation unit for black ink, 54C indicates a circulation unit for cyan ink, 54M indicates a circulation unit for magenta ink, and 54Y indicates an ink circulation unit for yellow ink. Each circulation unit has substantially the same configuration, and in this embodiment, when there is no need to distinguish between the circulation units, they are all referred to as circulation unit 54.

[0024] 2 and 3(a), the discharge unit 3 includes two discharge modules 300, a first support member 4, a second support member 7, an electric wiring member (electric wiring tape) 5, and an electric contact substrate 6. As shown in FIG. 3(b), the discharge module 300 includes a silicon substrate 310 having a thickness of 0.5 mm to 1 mm, and a plurality of discharge elements 15 provided on one side of the silicon substrate 310. In this embodiment, the discharge elements 15 are configured by electrothermal conversion elements (heaters) that generate thermal energy as discharge energy for discharging liquid. Electric power is supplied to each discharge element 15 via electric wiring formed on the silicon substrate 310 by a film formation technique.

[0025] Further, an ejection port forming member 320 is formed on the surface (lower surface in FIG. 3(b)) of the silicon substrate 310. In the ejection port forming member 320, a plurality of pressure chambers 12 corresponding to a plurality of ejection elements 15 and a plurality of ejection ports 13 for ejecting ink are formed by photolithography. Furthermore, a common supply flow path 18 and a common recovery flow path 19 are formed in the silicon substrate 310. Further, in the silicon substrate 310, a supply connection flow path 323 that communicates the common supply flow path 18 with each pressure chamber 12, and a recovery connection flow path 324 that communicates the common recovery flow path 19 with each pressure chamber 12 are formed. In this embodiment, one ejection module 300 is configured to eject two types of ink. That is, of the two ejection modules shown in FIG. 3(a), the ejection module 300 located on the left side of the figure ejects black ink and cyan ink, and the ejection module 300 located on the right side of the figure ejects magenta ink and yellow ink. Note that this combination is an example, and any combination of inks may be used. One ejection module may be configured to eject one type of ink, or may be configured to eject three or more types of ink. The two ejection modules 300 do not have to eject the same number of types of ink. One ejection module 300 may be provided, or may be configured to include three or more ejection modules 300. Furthermore, in the example shown in FIG. 3, two ejection port arrays extending in the Y direction are formed for one color of ink. A pressure chamber 12, a common supply flow path 18, and a common recovery flow path 19 are formed for each of the multiple ejection ports 13 that constitute each ejection port array.

[0026] An ink supply port and an ink recovery port, which will be described later, are formed on the back surface (upper surface in FIG. 3(b)) of the silicon substrate 310. The ink supply port supplies ink from an ink supply flow path 48 to the multiple common supply flow paths 18, and the ink recovery port recovers ink from the multiple common recovery flow paths 19 to an ink recovery flow path 49.

[0027] The ink supply port and ink recovery port referred to here refer to openings that supply and recover ink during forward ink circulation, which will be described later. That is, during forward ink circulation, ink is supplied from the ink supply port to each common supply flow path 18, and ink is recovered from each common recovery flow path 19 to the ink recovery port. However, ink may also be circulated in the reverse direction. In this case, ink is supplied from the ink recovery port described above to the common recovery flow path 19, and ink is recovered from the common supply flow path 18 to the ink supply port.

[0028] As shown in FIG. 3(a), the back surface (upper surface in FIG. 3(a)) of the ejection module 300 is adhesively fixed to one surface (lower surface in FIG. 3(a)) of the first support member 4. An ink supply flow path 48 and an ink recovery flow path 49 are formed in the first support member 4, penetrating from one surface to the other surface. One opening of the ink supply flow path 48 is connected to the aforementioned ink supply port in the silicon substrate 310, and one opening of the ink recovery flow path 49 is connected to the aforementioned ink recovery port in the silicon substrate 310. The ink supply flow path 48 and the ink recovery flow path 49 are provided independently for each type of ink.

[0029] A second support member 7 having an opening 7a (see FIG. 2) through which the ejection module 300 is inserted is adhesively fixed to one surface of the first support member 4 (the upper surface in FIG. 3(a)). The second support member 7 holds an electrical wiring member 5 that is electrically connected to the ejection module 300. The electrical wiring member 5 is a member for applying an electrical signal to the ejection module 300 to eject ink. The electrical connection portion between the ejection module 300 and the electrical wiring member 5 is sealed with a sealant (not shown) and is protected from corrosion by ink and external impacts.

[0030] Furthermore, an electrical contact board 6 is thermocompression bonded to an end 5a (see FIG. 2) of the electrical wiring member 5 using an anisotropic conductive film (not shown), and the electrical wiring member 5 and the electrical contact board 6 are electrically connected. The electrical contact board 6 has an external signal input terminal (not shown) for receiving an electrical signal from the liquid ejection device 50.

[0031] Furthermore, a joint member 8 (FIG. 3(a)) is provided between the first support member 4 and the circulation unit 54. A supply port 88 and a recovery port 89 are formed in the joint member 8 for each type of ink. The supply port 88 and the recovery port 89 communicate the ink supply flow path 48 and the ink recovery flow path 49 of the first support member 4 with the flow paths formed in the circulation unit 54. In FIG. 3(a), the supply port 88B and the recovery port 89B correspond to black ink, and the supply port 88C and the recovery port 89C correspond to cyan ink. Furthermore, the supply port 88M and the recovery port 89M correspond to magenta ink, and the supply port 88Y and the recovery port 89Y correspond to yellow ink.

[0032] The openings at one end of each of the ink supply flow passage 48 and the ink recovery flow passage 49 of the first support member 4 have a small opening area that matches the ink supply port and the ink recovery port in the silicon substrate 310. In contrast, the openings at the other end of each of the ink supply flow passage 48 and the ink recovery flow passage 49 of the first support member 4 have a shape that is expanded to the same opening area as the large opening area of ​​the joint member 8 formed to match the flow passage of the circulation unit 54. By adopting such a configuration, it is possible to suppress an increase in flow passage resistance to the ink collected from each recovery flow passage. However, the shapes of the openings at one end and the other end of each of the ink supply flow passage 48 and the ink recovery flow passage 49 are not limited to the above example.

[0033] In the liquid ejection head 1 having the above configuration, ink supplied to the circulation unit 54 passes through the supply port 88 of the joint member 8 and the ink supply flow path 48 of the first support member 4, and flows from the ink supply port of the ejection module 300 into the common supply flow path 18. The ink then flows from the common supply flow path 18 into the pressure chamber 12 via the supply connection flow path 323, and a portion of the ink that has flowed into the pressure chamber is ejected from the ejection port 13 by driving the ejection element 15. The remaining ink that has not been ejected passes from the pressure chamber 12 through the recovery connection flow path 324 and the common recovery flow path 19, and flows from the ink recovery port into the ink recovery flow path 49 of the first support member 4. The ink that has flowed into the ink recovery flow path 49 then flows into the circulation unit 54 via the recovery port 89 of the joint member 8, and is recovered.

[0034] <Components of the circulation unit> 4 is a schematic external view of one circulation unit 54 corresponding to one type of ink applied to the recording apparatus of this embodiment. The circulation unit 54 is provided with a filter 110, a first pressure adjustment means 120, a second pressure adjustment means 150, and a circulation pump 500. These components are connected by respective flow paths as shown in FIGS. 5 and 6, and constitute a circulation path that supplies and recovers ink to and from the ejection module 300 in the liquid ejection head 1.

[0035] <Circulation path inside the liquid ejection head> FIG. 5 is a vertical cross-sectional view showing a circulation path of one type of ink (one color ink) in the liquid ejection head 1. In order to explain the circulation path more clearly, the relative positions of each component (first pressure adjustment means 120, second pressure adjustment means 150, circulation pump 500, etc.) in FIG. 5 are simplified. Therefore, the relative positions of each component are different from the configuration in FIG. 19 described later. FIG. 6 is a block diagram showing the circulation path shown in FIG. 5. As shown in FIG. 5 and FIG. 6, the first pressure adjustment means 120 includes a first valve chamber 121 and a first pressure control chamber 122. The second pressure adjustment means 150 includes a second valve chamber 151 and a second pressure control chamber 152. The first pressure adjustment means 120 is configured to have a relatively higher control pressure than the second pressure adjustment means 150. In this embodiment, the two pressure adjustment means 120 and 150 are used to achieve circulation within a certain pressure range in the circulation path. Also, the ink is configured to flow through the pressure chamber 12 (ejection element 15) at a flow rate according to the pressure difference between the first pressure adjustment means 120 and the second pressure adjustment means 150. Below, the circulation path in the liquid ejection head 1 and the flow of ink within the circulation path will be described with reference to Figures 5 and 6. Note that the arrows in each figure indicate the direction of ink flow. A first exhaust flow path 801 and a second exhaust flow path 802 are respectively connected to the first pressure control chamber 122, and the first exhaust flow path 801 and the second exhaust flow path 802 are connected to the supply flow path 130. A third exhaust flow path 809 is provided in the lower part of the first pressure control chamber 122, and communicates with a third exhaust port 810 and further communicates with a bypass flow path 160. These will be described in detail later.

[0036] First, the connection state of each component of the liquid ejection head 1 will be described.

[0037] An external pump 21 that sends ink contained in an ink tank 2 (FIG. 6) provided outside the liquid ejection head 1 to the liquid ejection head 1 is connected to a circulation unit 54 via an ink supply tube 59 (FIG. 1). A filter 110 is provided in the ink flow path located upstream of the circulation unit 54. An ink supply path located downstream of the filter 110 is connected to a first valve chamber 121 of a first pressure adjustment means 120. The first valve chamber 121 communicates with a first pressure control chamber 122 via a communication port 191A that can be opened and closed by a valve 190A shown in FIG.

[0038] The first pressure control chamber 122 is connected to the supply flow path 130, the bypass flow path 160, and the pump outlet flow path 180 of the circulation pump 500. The supply flow path 130 is connected to the common supply flow path 18 via the ink supply port provided in the ejection module 300. The bypass flow path 160 is connected to a second valve chamber 151 provided in the second pressure adjustment means 150. The second valve chamber 151 is connected to the second pressure control chamber 152 via a communication port 191B that is opened and closed by a valve 190B shown in FIG. 5. Note that FIGS. 5 and 6 show an example in which one end of the bypass flow path 160 is connected to the first pressure control chamber 122 of the first pressure adjustment means 120, and the other end of the bypass flow path 160 is connected to the second valve chamber 151 of the second pressure adjustment means 150. However, one end of the bypass flow path 160 may be connected to the supply flow path 130, and the other end of the bypass flow path may be connected to the second valve chamber 151.

[0039] The second pressure control chamber 152 is connected to the recovery flow path 140. The recovery flow path 140 is connected to the common recovery flow path 19 via the ink recovery port provided in the ejection module 300. Furthermore, the second pressure control chamber 152 is connected to the circulation pump 500 via a pump inlet flow path 170. In addition, in FIG. 5, 170a indicates the inlet of the pump inlet flow path 170.

[0040] Next, a description will be given of the flow of ink in the liquid ejection head 1 having the above configuration. As shown in Fig. 6, the ink stored in the ink tank 2 is pressurized by an external pump 21 provided in the liquid ejection device 50, and is supplied to the circulation unit 54 of the liquid ejection head 1 as a positive pressure ink flow.

[0041] The ink supplied to the circulation unit 54 passes through the filter 110 to remove foreign matter such as dust and air bubbles, and then flows into the first valve chamber 121 provided in the first pressure adjustment means 120. The ink pressure decreases due to pressure loss when passing through the filter 110, but the ink pressure at this stage is positive. The ink that has flowed into the first valve chamber 121 then passes through the communication port 191A and flows into the first pressure control chamber 122 when the valve 190A is in the open state. Due to the pressure loss when passing through the communication port 191A, the ink that has flowed into the first pressure control chamber 122 switches from positive pressure to negative pressure.

[0042] Next, the flow of ink in the circulation path will be described. The circulation pump 500 operates to pump ink sucked from the pump inlet flow path 170 on the upstream side to the pump outlet flow path 180 on the downstream side. Therefore, when the pump is driven, the ink supplied to the first pressure control chamber 122 flows into the supply flow path 130 and the bypass flow path 160 together with the ink sent from the pump outlet flow path 180. Note that, although details will be described later, in this embodiment, a piezoelectric diaphragm pump using a piezoelectric element attached to a diaphragm as a driving source is used as a circulation pump capable of sending liquid. The piezoelectric diaphragm pump is a pump that changes the volume of the pump chamber by inputting a driving voltage to a piezoelectric element, and sends liquid by alternately moving two check valves due to pressure fluctuations.

[0043] The ink that has flowed into the supply flow channel 130 flows from the ink supply port of the ejection module 300 through the common supply flow channel 18 into the pressure chamber 12, and some of the ink is ejected from the ejection port 13 by driving (heat generation) the ejection element 15. The remaining ink that has not been used for ejection flows through the pressure chamber 12, passes through the common recovery flow channel 19, and then flows into the recovery flow channel 140 connected to the ejection module 300. The ink that has flowed into the recovery flow channel 140 flows into the second pressure control chamber 152 of the second pressure adjustment means 150.

[0044] On the other hand, the ink that has flowed from the first pressure control chamber 122 into the bypass flow path 160 flows into the second valve chamber 151, and then passes through the communication port 191B and flows into the second pressure control chamber 152. The ink that has flowed into the second pressure control chamber 152 via the bypass flow path 160 and the ink that has been recovered from the recovery flow path 140 are sucked into the circulation pump 500 via the pump inlet flow path 170 by the operation of the circulation pump 500. Then, the ink that has been sucked into the circulation pump 500 is sent to the pump outlet flow path 180 and flows into the first pressure control chamber 122 again. Thereafter, the ink that has flowed into the second pressure control chamber 152 from the first pressure control chamber 122 via the supply flow path 130 through the ejection module 300 and the ink that has flowed into the second pressure control chamber 152 via the bypass flow path 160 flows into the circulation pump 500. Then, the ink is sent from the circulation pump 500 to the first pressure control chamber 122. In this manner, the ink is circulated in the circulation path.

[0045] Here, the flow path that communicates the first pressure adjustment means 120 and the pressure chamber 12 is referred to as the first flow path, and the flow path that communicates the pressure chamber 12 and the circulation pump 500 is referred to as the second flow path. That is, the supply flow path 130 is referred to as the first flow path, and the recovery flow path 140, the second pressure adjustment means 150, and the pump inlet flow path 170 are collectively referred to as the second flow path. Note that the second flow path does not necessarily have to include the second pressure adjustment means 150 and the pump inlet flow path 170. The pump outlet flow path 180 is also referred to as the third flow path. Therefore, in this embodiment, the liquid flows through the circulation path of the circulation pump 500, the third flow path, the first pressure adjustment means 120, the first flow path, the pressure chamber 12, the second flow path, and the circulation pump 500 in this order.

[0046] As described above, in this embodiment, the circulation pump 500 can circulate the liquid along the circulation path formed in the liquid ejection head 1. This makes it possible to suppress thickening of the ink in the ejection module 300 and accumulation of sedimentation components of the ink color material, and makes it possible to maintain good ink fluidity in the ejection module 300 and ejection characteristics at the ejection ports.

[0047] In addition, since the circulation path in this embodiment is configured to be completed within the liquid ejection head 1, the length of the circulation path can be significantly shortened compared to when ink is circulated between the ink tank 2 provided outside the liquid ejection head and the liquid ejection head 1. This makes it possible to circulate the ink with a small circulation pump.

[0048] Furthermore, the connection flow path between the liquid ejection head 1 and the ink tank 2 is configured to include only a flow path for supplying ink. In other words, a configuration is adopted in which a flow path for recovering ink from the liquid ejection head 1 to the ink tank 2 is not required. Therefore, only a tube for supplying ink is required to connect the ink tank 2 and the liquid ejection head 1, and no tube for recovering ink is required. Therefore, the inside of the liquid ejection device 50 can be simplified with a reduced number of tubes, and the entire device can be made compact. Furthermore, by reducing the number of tubes, it is possible to reduce the pressure fluctuation of the ink caused by the oscillation of the tubes accompanying the main scanning of the liquid ejection head 1. In addition, the oscillation of the tubes during the main scanning of the liquid ejection head 1 becomes a driving load of the carriage motor that drives the carriage 60. Therefore, by reducing the number of tubes, the driving load of the carriage motor is reduced, and it is possible to simplify the main scanning mechanism including the carriage motor and the like. Furthermore, since it is not necessary to recover ink from the liquid ejection head to the ink tank, the external pump 21 can also be made compact. In this way, according to this embodiment, the liquid ejection device 50 can be made smaller and its costs reduced.

[0049] <Pressure Adjustment Means> FIG. 7 is a diagram showing an example of pressure adjustment means. The configuration and operation of the pressure adjustment means (first pressure adjustment means 120, second pressure adjustment means 150) built into the liquid ejection head 1 described above will be described in more detail with reference to FIG. 7. The first pressure adjustment means 120 and the second pressure adjustment means 150 have substantially the same configuration. For this reason, the first pressure adjustment means 120 will be described below as an example, and the second pressure adjustment means 150 will only be described with the reference numerals of the parts corresponding to the first pressure adjustment means in FIG. 7. In the case of the second pressure adjustment means 150, the first valve chamber 121 described below will be read as the second valve chamber 151, and the first pressure control chamber 122 will be read as the second pressure control chamber 152.

[0050] The first pressure adjustment means 120 has a first valve chamber 121 and a first pressure control chamber 122 formed in a cylindrical housing 125. The first valve chamber 121 and the first pressure control chamber 122 are separated by a partition wall 123 provided in the cylindrical housing 125. However, the first valve chamber 121 communicates with the first pressure control chamber 122 through a communication port 191 formed in the partition wall 123. The first valve chamber 121 is provided with a valve 190 that switches between communication and blocking between the first valve chamber 121 and the first pressure control chamber 122 at the communication port 191. The valve 190 is held at a position facing the communication port 191 by a valve spring 200, and has a configuration that allows it to come into close contact with the partition wall 123 by the biasing force of the valve spring 200. When the valve 190 comes into close contact with the partition wall 123, the flow of ink through the communication port 191 is blocked. In order to increase the close contact with the partition 123, it is preferable that the portion of the valve 190 that comes into contact with the partition 123 is made of an elastic material. A valve shaft 190a that is inserted into the communication port 191 protrudes from the center of the valve 190. By pressing this valve shaft 190a against the biasing force of a valve spring 200, the valve 190 moves away from the partition 123, allowing ink to flow through the communication port 191. Hereinafter, the state in which the valve 190 blocks the flow of ink through the communication port 191 is referred to as the "closed state," and the state in which ink can flow through the communication port 191 is referred to as the "open state."

[0051] The opening of the cylindrical housing 125 is closed by the flexible member 230 and the pressure plate 210. The first pressure control chamber 122 is formed by the flexible member 230, the pressure plate 210, the peripheral wall of the housing 125, and the partition wall 123. The first pressure control chamber 122 is variable in volume, and the pressure plate 210 is configured to be displaceable in accordance with the displacement of the flexible member 230. The materials of the pressure plate 210 and the flexible member 230 are not particularly limited, but for example, the pressure plate 210 can be configured from a resin molded part, and the flexible member 230 can be configured from a resin film. In this case, the pressure plate 210 can be fixed to the flexible member 230 by thermal welding.

[0052] A pressure adjustment spring 220 (biasing member) is provided between the pressure plate 210 and the partition wall 123. The pressure plate 210 and the flexible member 230 are biased by the biasing force of the pressure adjustment spring 220 in a direction in which the internal volume of the first pressure control chamber 122 expands, as shown in FIG. 7(a). When the pressure in the first pressure control chamber 122 decreases, the pressure plate 210 and the flexible member 230 are displaced in a direction in which the internal volume of the first pressure control chamber 122 decreases against the pressure of the pressure adjustment spring 220. When the internal volume of the first pressure control chamber 122 decreases to a certain amount, the pressure plate 210 abuts against the valve shaft 190a of the valve 190. When the internal volume of the first pressure control chamber 122 further decreases thereafter, the valve 190 moves together with the valve shaft 190a against the biasing force of the valve spring 200, and moves away from the partition wall 123. As a result, the communication port 191 is in an open state (the state shown in FIG. 7(b)).

[0053] In this embodiment, the connection in the circulation path is set so that the pressure in the first valve chamber 121 when the communication port 191 is in the open state is higher than the pressure in the first pressure control chamber 122. As a result, when the communication port 191 is in the open state, ink flows from the first valve chamber 121 to the first pressure control chamber 122. This ink flow causes the flexible member 230 and the pressure plate 210 to be displaced in a direction in which the internal volume of the first pressure control chamber 122 increases. As a result, the pressure plate 210 moves away from the valve shaft 190a of the valve 190, and the valve 190 is brought into close contact with the partition wall 123 by the biasing force of the valve spring 200, and the communication port 191 is in the closed state (the state of FIG. 7(c)).

[0054] In this manner, in the first pressure adjustment means 120 of this embodiment, when the pressure in the first pressure control chamber 122 decreases to a certain pressure or below (for example, when the negative pressure becomes stronger), ink flows in from the first valve chamber 121 via the communication port 191. This prevents the pressure in the first pressure control chamber 122 from decreasing any further. Therefore, the pressure in the first pressure control chamber 122 is controlled to be kept within a certain range.

[0055] Next, the pressure in the first pressure control chamber 122 will be described in more detail.

[0056] Consider a state in which the flexible member 230 and the pressure plate 210 are displaced in response to the pressure in the first pressure control chamber 122 as described above, and the pressure plate 210 comes into contact with the valve shaft 190a, opening the communication port 191 (the state shown in FIG. 7(b)). At this time, the relationship of the forces acting on the pressure plate 210 is expressed by the following equation 1.

[0057] P2×S2+F2+(P1-P2)×S1+F1=0...Equation 1 Furthermore, rearranging Equation 1 for P2 gives P2=-(F1+F2+P1×S1) / (S2-S1)...Equation 2 It becomes.

[0058] P1: Pressure (gauge pressure) of the first valve chamber 121 P2: Pressure (gauge pressure) of the first pressure control chamber 122 F1: Valve spring force 200 F2: Spring force of the pressure adjusting spring 220 S1: Pressure receiving area of ​​valve 190 S2: Pressure receiving area of ​​the pressure plate 210 Here, the spring force F1 of the valve spring 200 and the spring force F2 of the pressure adjustment spring 220 are positive (leftward in FIG. 7) in the direction pressing the valve 190 and the pressure plate 210. In addition, the pressure P1 in the first valve chamber 121 and the pressure P2 in the first pressure control chamber 122 are configured so that P1 satisfies the relationship P1≧P2.

[0059] The pressure P2 in the first pressure control chamber 122 when the communication port 191 is open is determined by formula 2, and when the communication port 191 is open, due to the relationship P1≧P2, ink flows from the first valve chamber 121 into the first pressure control chamber 122. As a result, the pressure P2 in the first pressure control chamber 122 does not decrease any further, and P2 is maintained within a certain pressure range.

[0060] On the other hand, as shown in FIG. 7(c), when the pressure plate 210 is not in contact with the valve shaft 190a and the communication port 191 is closed, the relationship of the forces acting on the pressure plate 210 is expressed by Equation 3.

[0061] P3×S3+F3=0...Equation 3 Now, rearrange Equation 3 for P3 as follows: P3 = -F3 / S3 Equation 4 It becomes.

[0062] F3: The spring force of the pressure adjusting spring 220 when the pressure plate 210 and the valve shaft 190a are not in contact with each other P3: pressure (gauge pressure) in the first pressure control chamber 122 when the pressure plate 210 and the valve shaft 190a are not in contact with each other S3: The pressure-receiving area of ​​the pressure plate 210 when the pressure plate 210 and the valve 190 are not in contact with each other Here, FIG. 7(c) shows a state in which the pressure plate 210 and the flexible member 230 are displaced to the right side of the figure to the limit of their displacement. The pressure P3 in the first pressure control chamber 122, the spring force F3 of the pressure adjustment spring 220, and the pressure receiving area S3 of the pressure plate 210 change according to the amount of displacement while the pressure plate 210 and the flexible member 230 are displaced to the state of FIG. 7(c). Specifically, when the pressure plate 210 and the flexible member 230 are in the left direction in FIG. 7 compared to FIG. 7(c), the pressure receiving area S3 of the pressure plate 210 becomes smaller, and the spring force F3 of the pressure adjustment spring 220 becomes larger. As a result, the pressure P3 in the first pressure control chamber 122 becomes smaller according to the relationship of Equation 4. Therefore, according to Equation 2 and Equation 4, the pressure in the first pressure control chamber 122 gradually increases from the state of FIG. 7(b) to the state of FIG. 7(c) (i.e., the negative pressure becomes weaker and approaches the positive pressure side). That is, from a state in which the communication port 191 is open, the pressure plate 210 and the flexible member 230 gradually displace to the right, and the pressure in the first pressure control chamber 122 gradually increases until the internal volume of the first pressure control chamber 122 finally reaches its limit of displacement. In other words, the negative pressure weakens. In this embodiment, the first pressure adjustment means 120 adjusts the pressure of the liquid in the first flow path, and the second pressure adjustment means 150 adjusts the pressure of the liquid in the pump inlet flow path 170 (in the inlet flow path).

[0063] <Circulation pump> Next, the configuration and operation of the circulation pump 500 built into the above-mentioned liquid ejection head 1 will be described in detail with reference to FIGS.

[0064] FIG. 8 is an external perspective view of the circulation pump 500. FIG. 8(a) is an external perspective view showing the front side of the circulation pump 500, and FIG. 8(b) is an external perspective view showing the rear side of the circulation pump 500. The outer shell of the circulation pump 500 is composed of a pump housing 505 and a cover 507 fixed to the pump housing 505. The pump housing 505 is composed of a housing body 505a and a flow path connecting member 505b adhesively fixed to the outer surface of the housing body 505a. The housing body 505a and the flow path connecting member 505b each have a pair of through holes communicating with each other at two different positions. The pair of through holes provided at one position forms a pump supply hole 501, and the pair of through holes provided at the other position forms a pump discharge hole 502. The pump supply hole 501 is connected to the pump inlet flow path 170 connected to the second pressure control chamber 152, and the pump discharge hole 502 is connected to the pump outlet flow path 180 connected to the first pressure control chamber 122. Ink supplied from pump supply hole 501 passes through a pump chamber 503 (see FIG. 9) described below, and is discharged from pump discharge hole 502.

[0065] FIG. 9 is a cross-sectional view of the circulating pump 500 shown in FIG. 8(a) taken along line IX-IX. A diaphragm 506 is joined to the inner surface of the pump housing 505, and a pump chamber 503 is formed between the diaphragm 506 and a recess formed on the inner surface of the pump housing 505. The pump chamber 503 communicates with a pump supply hole 501 and a pump discharge hole 502 formed in the pump housing 505. A check valve 504a is provided in the middle of the pump supply hole 501, and a check valve 504b is provided in the middle of the pump discharge hole 502. That is, the circulating pump 500 is provided with a check valve in a flow path that communicates the second flow path and the third flow path. Specifically, the check valve 504a is arranged so that a part of the check valve 504a can move leftward in the figure in a space 512a formed in the middle of the pump supply hole 501. Also, the check valve 504b is disposed in a space 512b, a part of which is formed in the middle portion of the pump discharge hole 502, so as to be movable to the right in the figure.

[0066] When diaphragm 506 is displaced to increase the volume of pump chamber 503 and reduce the pressure in pump chamber 503, check valve 504a moves away from the opening of pump supply hole 501 in space 512a (i.e., moves to the left in the figure). When check valve 504a moves away from the opening of pump supply hole 501 in space 512a, the check valve 504a enters an open state that allows the flow of ink through pump supply hole 501. When diaphragm 506 is displaced to decrease the volume of pump chamber 503 and reduce the pressure in pump chamber 503, check valve 504a comes into close contact with the wall surface surrounding the opening of pump supply hole 501. As a result, the check valve 504a enters a closed state that blocks the flow of ink through pump supply hole 501.

[0067] On the other hand, when the pump chamber 503 is depressurized, the check valve 504b comes into close contact with the wall surface surrounding the opening of the pump housing 505 and enters a closed state in which it blocks the flow of ink through the pump discharge hole 502. When the pump chamber 503 is pressurized, the check valve 504b moves away from the opening of the pump housing 505 toward the space 512b (i.e., moves to the right in the figure), allowing the flow of ink through the pump discharge hole 502.

[0068] The material of each of the check valves 504a and 504b may be any material that can deform in response to the pressure in the pump chamber 503, and may be, for example, an elastic material such as EPDM or elastomer, or a film or thin plate such as polypropylene, but is not limited to these.

[0069] As described above, pump chamber 503 is formed by joining pump housing 505 and diaphragm 506. Therefore, the pressure in pump chamber 503 changes as diaphragm 506 deforms. For example, when diaphragm 506 is displaced toward pump housing 505 (displaced to the right in the figure) and the volume of pump chamber 503 decreases, the pressure in pump chamber 503 increases. As a result, check valve 504b arranged opposite pump discharge hole 502 opens, and ink in pump chamber 503 is discharged. At this time, check valve 504a arranged opposite pump supply hole 501 is in close contact with the wall surface surrounding pump supply hole 501, so that the backflow of ink from pump chamber 503 to pump supply hole 501 is suppressed.

[0070] Conversely, when the diaphragm 506 is displaced in the direction in which the pump chamber 503 expands, the pressure in the pump chamber 503 decreases. As a result, the check valve 504a arranged opposite the pump supply hole 501 opens, and ink is supplied to the pump chamber 503. At this time, the check valve 504b arranged at the pump discharge hole 502 comes into close contact with the wall surface surrounding the opening formed in the pump housing 505 and closes the opening. As a result, the backflow of ink from the pump discharge hole 502 to the pump chamber 503 is suppressed.

[0071] In this way, in the circulation pump 500, the diaphragm 506 deforms, changing the pressure in the pump chamber 503, thereby sucking in and discharging ink. At this time, if bubbles get into the pump chamber 503, even if the diaphragm 506 is displaced, the bubbles expand and contract, reducing the pressure change in the pump chamber 503 and decreasing the amount of liquid delivered. Therefore, the pump chamber 503 is arranged parallel to gravity to make it easier for bubbles that get into the pump chamber 503 to gather above the pump chamber 503, and the pump discharge hole 502 is arranged above the center of the pump chamber 503. This makes it possible to improve the discharge of bubbles in the pump and stabilize the flow rate.

[0072] <Ink flow inside the liquid ejection head> FIG. 10 is a diagram for explaining the flow of ink in the liquid ejection head. The circulation of ink in the liquid ejection head 1 will be explained with reference to FIG. 10. In order to more clearly explain the ink circulation path, the relative positions of each component (first pressure adjustment means 120, second pressure adjustment means 150, circulation pump 500, etc.) in FIG. 10 are simplified. Therefore, the relative positions of each component are different from the configuration in FIG. 19 described later. FIG. 10(a) is a schematic diagram showing the flow of ink when a recording operation is performed in which ink is ejected from the ejection port 13 to perform recording. The arrows in the figure indicate the flow of ink. In this embodiment, when a recording operation is performed, both the external pump 21 and the circulation pump 500 start to be driven. The external pump 21 and the circulation pump 500 may be driven regardless of the recording operation. The external pump 21 and the circulation pump 500 may not be driven in conjunction with each other, and may be driven independently.

[0073] During the recording operation, the circulation pump 500 is ON (driven), and the ink flowing out from the first pressure control chamber 122 flows into the supply flow path 130 and the bypass flow path 160. The ink that flows into the supply flow path 130 passes through the ejection module 300, then flows into the recovery flow path 140, and is then supplied to the second pressure control chamber 152.

[0074] On the other hand, the ink that has flowed into the bypass flow path 160 from the first pressure control chamber 122 flows into the second pressure control chamber 152 via the second valve chamber 151. The ink that has flowed into the second pressure control chamber 152 passes through the pump inlet flow path 170, the circulation pump 500, and the pump outlet flow path 180, and then flows into the first pressure control chamber 122 again. At this time, the control pressure by the first valve chamber 121 is set higher than the control pressure of the first pressure control chamber 122 based on the relationship of the above-mentioned formula 2. Therefore, the ink in the first pressure control chamber 122 is supplied to the ejection module 300 again via the supply flow path 130 without flowing into the first valve chamber 121. The ink that has flowed into the ejection module 300 flows into the first pressure control chamber 122 again via the recovery flow path 140, the second pressure control chamber 152, the pump inlet flow path 170, the circulation pump 500, and the pump outlet flow path 180. In this manner, the ink circulation that is completed within the liquid ejection head 1 is performed.

[0075] In the above ink circulation, the amount of ink circulating (flow rate) in the ejection module 300 is determined by the difference in the control pressure between the first pressure control chamber 122 and the second pressure control chamber 152. This pressure difference is set so as to be a circulation amount capable of suppressing thickening of ink near the ejection port in the ejection module 300. In addition, the ink consumed by recording is supplied from the ink tank 2 to the first pressure control chamber 122 via the filter 110 and the first valve chamber 121. The mechanism by which the consumed ink is supplied will be described in detail. By reducing the ink from the circulation path by the amount of ink consumed by recording, the pressure in the first pressure control chamber is reduced, and as a result, the ink in the first pressure control chamber 122 is also reduced. As the ink in the first pressure control chamber 122 is reduced, the internal volume of the first pressure control chamber 122 is reduced. Due to this reduction in the internal volume of the first pressure control chamber 122, the communication port 191A is opened, and ink is supplied from the first valve chamber 121 to the first pressure control chamber 122. This supplied ink experiences a pressure loss when passing from first valve chamber 121 through communication port 191A, and as it flows into first pressure control chamber 122, the ink changes from a positive pressure state to a negative pressure state. As ink flows from first valve chamber 121 into first pressure control chamber 122, the pressure inside the first pressure control chamber increases, increasing the internal volume of the first pressure control chamber and closing communication port 191A. In this way, communication port 191A alternates between an open state and a closed state depending on the consumption of ink. Furthermore, if ink is not consumed, communication port 191A is maintained in a closed state.

[0076] FIG. 10B is a schematic diagram showing the flow of ink immediately after the recording operation is completed and the circulation pump 500 is turned off (stopped). When the recording operation is completed and the circulation pump 500 is turned off, the pressures of the first pressure control chamber 122 and the second pressure control chamber 152 are both at the control pressure during the recording operation. Therefore, the ink moves as shown in FIG. 10B according to the pressure difference between the pressures of the first pressure control chamber 122 and the second pressure control chamber 152. Specifically, the ink continues to flow from the first pressure control chamber 122 to the ejection module 300 via the supply flow path 130, and then to the second pressure control chamber 152 via the recovery flow path 140. The ink also continues to flow from the first pressure control chamber 122 to the second pressure control chamber 152 via the bypass flow path 160 and the second valve chamber 151.

[0077] The amount of ink that has moved from the first pressure control chamber 122 to the second pressure control chamber 152 by these ink flows is supplied to the first pressure control chamber 122 from the ink tank 2 via the filter 110 and the first valve chamber 121. Therefore, the content volume in the first pressure control chamber 122 is kept constant. From the relationship of the above-mentioned formula 2, when the content volume in the first pressure control chamber 122 is constant, the spring force F1 of the valve spring 200, the spring force F2 of the pressure adjustment spring 220, the pressure receiving area S1 of the valve 190, and the pressure receiving area S2 of the pressure plate 210 are kept constant. Therefore, the pressure in the first pressure control chamber 122 is determined according to the change in the pressure (gauge pressure) P1 in the first valve chamber 121. Therefore, when there is no change in the pressure P1 in the first valve chamber 121, the pressure P2 in the first pressure control chamber 122 is kept at the same pressure as the control pressure during the recording operation.

[0078] On the other hand, the pressure of the second pressure control chamber 152 changes over time according to the change in the content volume caused by the inflow of ink from the first pressure control chamber 122. Specifically, from the state of FIG. 10(b) until the communication port 191 is closed and the second valve chamber 151 and the second pressure control chamber 152 are not in communication with each other as shown in FIG. 10(c), the pressure of the second pressure control chamber 152 changes according to the formula 2. Thereafter, the pressure plate 210 and the valve shaft 190a are not in contact with each other and the communication port 191 is closed. Then, as shown in FIG. 10(d), ink flows from the recovery passage 140 into the second pressure control chamber 152. This ink inflow displaces the pressure plate 210 and the flexible member 230, and the pressure of the second pressure control chamber 152 changes according to the formula 4 until the internal volume of the second pressure control chamber 152 reaches its maximum. That is, it rises.

[0079] 10(c), no ink flow occurs from the first pressure control chamber 122 to the second pressure control chamber 152 via the bypass flow path 160 and the second valve chamber 151. Therefore, after the ink in the first pressure control chamber 122 is supplied to the ejection module 300 via the supply flow path 130, only a flow occurs to the second pressure control chamber 152 via the recovery flow path 140. As described above, the movement of ink from the first pressure control chamber 122 to the second pressure control chamber 152 occurs according to the pressure difference between the pressure in the first pressure control chamber 122 and the pressure in the second pressure control chamber 152. Therefore, when the pressure in the second pressure control chamber 152 becomes equal to the pressure in the first pressure control chamber 122, the movement of ink stops.

[0080] In addition, in a state where the pressure in the second pressure control chamber 152 is equal to the pressure in the first pressure control chamber 122, the second pressure control chamber 152 expands to a state shown in FIG. 10(d). When the second pressure control chamber 152 expands as shown in FIG. 10(d), a storage portion capable of storing ink is formed in the second pressure control chamber 152. The time required from stopping the circulation pump 500 to transition to the state shown in FIG. 10(d) is about 1 to 2 minutes, which may vary depending on the shape and size of the flow path and the properties of the ink. When the circulation pump 500 is driven from the state shown in FIG. 10(d) where ink is stored in the storage portion, the ink in the storage portion is supplied to the first pressure control chamber 122 by the circulation pump 500. As a result, the amount of ink in the first pressure control chamber 122 increases as shown in FIG. 10(e), and the flexible member 230 and the pressure plate 210 are displaced in the expansion direction. Then, when the circulation pump 500 continues to be driven, the state inside the circulation path changes as shown in FIG. 10(a).

[0081] 10(a) is an example of the ink circulation during the printing operation, but as described above, the ink may be circulated without the printing operation. Even in this case, the ink flows as shown in FIGS. 10(a) to 10(e) according to the driving and stopping of the circulation pump 500.

[0082] As described above, in this embodiment, the communication port 191B in the second pressure adjustment means 150 is in an open state when the circulation pump 500 is driven to circulate the ink, and is in a closed state when the circulation of the ink stops, but this is not limited to the above example. The control pressure may be set so that the communication port 191B in the second pressure adjustment means 150 is in a closed state even when the circulation pump 500 is driven to circulate the ink. Hereinafter, the role of the bypass flow path 160 will be specifically described.

[0083] The bypass flow path 160 connecting the first pressure adjustment means 120 and the second pressure adjustment means 150 is provided to prevent the negative pressure generated in the circulation path from being affected by the discharge module 300 when the negative pressure exceeds a predetermined value. The bypass flow path 160 is also provided to supply ink to the pressure chamber 12 from both sides of the supply flow path 130 and the recovery flow path 140.

[0084] First, an example will be described in which the bypass flow path 160 is provided to prevent the negative pressure from being influenced by the discharge module 300 when the negative pressure becomes stronger than a preset value. For example, the ink characteristics (e.g., viscosity) may change due to a change in the environmental temperature. When the ink viscosity changes, the pressure loss in the circulation path also changes. For example, when the ink viscosity decreases, the pressure loss in the circulation path decreases. As a result, the flow rate of the circulation pump 500 driven at a constant drive amount increases, and the flow rate through the discharge module 300 increases. On the other hand, since the discharge module 300 is kept at a constant temperature by a temperature adjustment mechanism (not shown), the viscosity of the ink in the discharge module 300 is maintained constant even if the environmental temperature changes. While the viscosity of the ink in the discharge module 300 does not change, the flow rate of the ink flowing through the discharge module 300 increases, and the negative pressure in the discharge module 300 is strengthened due to flow resistance. In this way, if the negative pressure in the discharge module 300 becomes stronger than the default value, the meniscus of the discharge port 13 may be destroyed, and external air may be drawn into the circulation path, preventing normal discharge. Even if the meniscus is not destroyed, the negative pressure in the pressure chamber 12 may become stronger than the default value, affecting discharge.

[0085] For this reason, in this embodiment, the bypass flow path 160 is formed in the circulation path. By providing the bypass flow path 160, when the negative pressure becomes stronger than a preset value, ink also flows through the bypass flow path 160, so that the pressure of the ejection module 300 can be kept constant. Therefore, for example, the communication port 191B in the second pressure adjustment means 150 may be configured with a control pressure that maintains the closed state even when the circulation pump 500 is being driven. Then, the control pressure in the second pressure adjustment means may be set so that the communication port 191 in the second pressure adjustment means 150 is in an open state when the negative pressure becomes stronger than a preset value. In other words, if the meniscus does not collapse even when the flow rate of the pump is changed due to a viscosity change such as an environmental change, or if a predetermined negative pressure is maintained, the communication port 191B may be in a closed state when the circulation pump 500 is driven.

[0086] Next, an example will be described in which the bypass flow path 160 is provided to supply ink to the pressure chamber 12 from both the supply flow path 130 and the recovery flow path 140. Pressure fluctuations in the circulation path can also occur due to the ejection operation of the ejection element 15. Ink is drawn into the pressure chamber with the ejection operation. This is because a compressive force is generated.

[0087] Below, it will be explained that when high duty recording continues, the ink supplied to the pressure chamber 12 is supplied to both the supply flow path 130 side and the recovery flow path 140 side. Note that the definition of duty can change depending on various conditions, but here, the state in which one 4pl ink droplet is recorded on a 1200dpi grid is treated as 100%. High duty recording means, for example, recording at a duty of 100%.

[0088] If recording at a high duty continues, the amount of ink flowing from the pressure chamber 12 into the second pressure control chamber 152 through the recovery flow path 140 decreases. On the other hand, since the circulation pump 500 causes a constant amount of ink to flow out, the balance between the inflow and outflow in the second pressure control chamber 152 is lost, the ink in the second pressure control chamber 152 decreases, the negative pressure in the second pressure control chamber 152 becomes stronger, and the second pressure control chamber 152 shrinks. Then, as the negative pressure in the second pressure control chamber 152 becomes stronger, the inflow amount of ink flowing into the second pressure control chamber 152 through the bypass flow path 160 increases, and the second pressure control chamber 152 becomes stable with the outflow and inflow balanced. As a result, the negative pressure in the second pressure control chamber 152 becomes stronger according to the duty. Furthermore, as described above, when the circulation pump 500 is driven, in a configuration in which the communication port 191B is in a closed state, the communication port 191B opens depending on the duty, and ink flows from the bypass flow path 160 into the second pressure control chamber 152.

[0089] Then, when recording at an even higher duty is continued, the amount of ink flowing from the pressure chamber 12 into the second pressure control chamber 152 through the recovery flow passage 140 decreases, and instead the amount of ink flowing into the second pressure control chamber 152 from the communication port 191B via the bypass flow passage 160 increases. If this state progresses further, the amount of ink flowing from the pressure chamber 12 into the second pressure control chamber 152 through the recovery flow passage 140 becomes zero, and all ink flowing out to the circulation pump 500 becomes ink flowing in from the communication port 191B. If this state progresses further, ink now flows back from the second pressure control chamber 152 into the pressure chamber 12 through the recovery flow passage 140. In this state, the ink flowing out from the second pressure control chamber 152 to the circulation pump 500 and the ink flowing out to the pressure chamber 12 flow into the second pressure control chamber 152 from the communication port 191B through the bypass flow passage 160. In this case, the pressure chamber 12 is filled with ink from the supply flow passage 130 and ink from the recovery flow passage 140, and is ejected.

[0090] Incidentally, the backflow of ink occurring when the recording duty is high is a phenomenon that occurs due to the provision of the bypass flow path 160. Also, in the above, an example has been described in which the communication port 191B in the second pressure adjustment means is opened in response to the backflow of ink, but the backflow of ink may occur when the communication port 191B in the second pressure adjustment means is in an open state. Even in a configuration in which the second pressure adjustment means is not provided, the backflow of ink may occur due to the provision of the bypass flow path 160. Incidentally, it is sufficient that the bypass flow path 160 communicates at least one of the first flow path or the first pressure adjustment means 120 with the second flow path without passing through the pressure chamber 12.

[0091] <Configuration of the discharge unit> FIG. 11 is a schematic diagram showing a circulation path for one color of ink in the discharge unit 3 of this embodiment. FIG. 11(a) is an exploded perspective view of the discharge unit 3 seen from the first support member 4 side, and FIG. 11(b) is an exploded perspective view of the discharge unit 3 seen from the discharge module 300 side. The arrows indicated by IN and OUT in the figure indicate the flow of ink, and the flow of ink for only one color will be described, but the other colors flow in the same manner. Also, the second support member 7 and the electric wiring member 5 are omitted in FIG. 11, and are also omitted in the following description of the configuration of the discharge unit. Also, the first support member 4 in FIG. 11(a) shows a cross section taken along line XI-XI in FIG. 3. The discharge module 300 includes a discharge element substrate 340 and an aperture plate 330. FIG. 12 is a diagram showing the aperture plate 330, and FIG. 13 is a diagram showing the discharge element substrate 340.

[0092] Ink is supplied to the discharge unit 3 from the circulation unit 54 via a joint member 8 (see FIG. 3). The ink path from when the ink passes through the joint member 8 until when the ink returns to the joint member 8 will be described. Note that the joint member 8 will be omitted from the following drawings.

[0093] The ejection module 300 includes an ejection element substrate 340, which is a silicon substrate 310, and an aperture plate 330, and further includes an ejection port forming member 320. The ejection element substrate 340, the aperture plate 330, and the ejection port forming member 320 are overlapped and joined together so that the ink flow paths communicate with each other to form the ejection module 300, which is supported by a first support member 4. The ejection module 300 is supported by the first support member 4 to form an ejection unit 3. The ejection element substrate 340 includes an ejection port forming member 320, which includes a plurality of ejection port rows in which a plurality of ejection ports 13 are arranged in a row, and ejects a portion of the ink supplied through the ink flow path in the ejection module 300 from the ejection port 13. Ink that is not ejected is collected through the ink flow path in the ejection module 300.

[0094] As shown in Figs. 11 and 12, the opening plate 330 has a plurality of arranged ink supply ports 311 and a plurality of arranged ink recovery ports 312. As shown in Figs. 13 and 14, the ejection element substrate 340 has a plurality of arranged supply connection channels 323 and a plurality of arranged recovery connection channels 324. The ejection element substrate 340 further has a common supply channel 18 communicating with the plurality of supply connection channels 323 and a common recovery channel 19 communicating with the plurality of recovery connection channels 324. The ink flow channels in the ejection unit 3 are formed by communicating an ink supply channel 48 and an ink recovery channel 49 (see Fig. 3) provided in the first support member 4 with a flow channel provided in the ejection module 300. The support member supply port 211 is a cross-sectional opening that forms the ink supply channel 48, and the support member recovery port 212 is a cross-sectional opening that forms the ink recovery channel 49.

[0095] Ink supplied to the ejection unit 3 is supplied from the circulation unit 54 (see FIG. 3(a)) side to the ink supply flow path 48 (see FIG. 3(a)) of the first support member 4. The ink flowing through the support member supply port 211 in the ink supply flow path 48 is supplied to the common supply flow path 18 of the ejection element substrate 340 via the ink supply flow path 48 (see FIG. 3(a)) and the ink supply port 311 of the opening plate 330, and enters the supply connection flow path 323. This is the supply side flow path. After that, the ink flows through the pressure chamber 12 (see FIG. 3(b)) of the ejection port forming member 320 to the recovery connection flow path 324 of the recovery side flow path. The flow of ink in the pressure chamber 12 will be described in detail later.

[0096] In the recovery side flow path, the ink that has entered the recovery connection flow path 324 flows into the common recovery flow path 19. Thereafter, the ink flows from the common recovery flow path 19 through the ink recovery port 312 of the opening plate 330 to the ink recovery flow path 49 of the first support member 4, and then through the support member recovery port 212 to be recovered in the circulation unit 54.

[0097] The area of ​​the opening plate 330 without the ink supply port 311 or the ink recovery port 312 corresponds to the area for separating the support member supply port 211 and the support member recovery port 212 in the first support member 4. Moreover, this area does not have an opening in the first support member 4 either. Such an area is used as an adhesion area when the ejection module 300 and the first support member 4 are adhered to each other.

[0098] In FIG. 12, the aperture plate 330 has a plurality of rows of apertures arranged in the X direction, and the supply (IN) apertures and the recovery (OUT) apertures are arranged alternately in the Y direction so as to be shifted by half a pitch in the X direction. In FIG. 13, the ejection element substrate 340 has a common supply flow path 18 communicating with a plurality of supply connection flow paths 323 arranged in the Y direction, and a common recovery flow path 19 communicating with a plurality of recovery connection flow paths 324 arranged in the Y direction, arranged alternately in the X direction. The common supply flow paths 18 and the common recovery flow path 19 are separated for each type of ink, and further, the number of common supply flow paths 18 and common recovery flow paths 19 is determined according to the number of ejection port rows of each color. In addition, the supply connection flow paths 323 and the recovery connection flow paths 324 are also arranged in the number corresponding to the ejection ports 13. It is not necessarily required that they correspond one-to-one, and one supply connection flow path 323 and one recovery connection flow path 324 may correspond to a plurality of ejection ports 13.

[0099] Such an opening plate 330 and an ejection element substrate 340 are overlapped and joined so that the flow paths of each ink are connected to form an ejection module 300, and by being supported by the first support member 4, an ink flow path is formed that has the above-mentioned supply flow path and recovery flow path.

[0100] Fig. 14(a) to (c) are cross-sectional views showing ink flows in different parts of the discharge unit 3. Fig. 14(a) is a cross-section shown by XIVa-XIVa in Fig. 11(a) and shows a cross-section of a part where the ink supply flow path 48 and the ink supply port 311 in the discharge unit 3 communicate with each other. Fig. 14(b) is a cross-section shown by XIVb-XIVb in Fig. 11(a) and shows a cross-section of a part where the ink recovery flow path 49 and the ink recovery port 312 in the discharge unit 3 communicate with each other. Fig. 14(c) is a cross-section shown by XIVc-XIVc in Fig. 11(a) and shows a cross-section of a part where the ink supply port 311 and the ink recovery port 312 do not communicate with the flow path of the first support member 4.

[0101] In the supply flow path for supplying ink, as shown in FIG. 14(a), ink is supplied from a portion where the ink supply flow path 48 of the first support member 4 and the ink supply port 311 of the opening plate 330 overlap and communicate with each other. In the recovery flow path for recovering ink, as shown in FIG. 14(b), ink is recovered from a portion where the ink recovery flow path 49 of the first support member 4 and the ink recovery port 312 of the opening plate 330 overlap and communicate with each other. In addition, as shown in FIG. 14(c), in the ejection unit 3, there is also a region where the opening plate 330 does not have an opening. In such a region, ink is not supplied or recovered between the ejection element substrate 340 and the first support member 4. As shown in FIG. 14(a), ink is supplied in a region where the ink supply port 311 is provided, and as shown in FIG. 14(b), ink is recovered in a region where the ink recovery port 312 is provided. In the present embodiment, the configuration using the opening plate 330 has been described as an example, but the opening plate 330 may not be used. For example, a configuration may be used in which flow paths corresponding to the ink supply flow path 48 and the ink recovery flow path 49 are formed in the first support member 4, and the ejection element substrate 340 is joined to the first support member 4.

[0102] 15(a) and (b) are cross-sectional views showing the vicinity of the ejection port 13 in the ejection module 300, and FIG. 16 is a cross-sectional view showing an ejection module having a configuration in which the common supply flow path 18 and the common recovery flow path 19 are expanded in the X direction as a comparative example. Note that the thick arrows shown in the common supply flow path 18 and the common recovery flow path 19 in FIG. 15 and FIG. 16 indicate the oscillation of ink in a configuration in which a serial type liquid ejection device 50 is used. The ink supplied to the pressure chamber 12 via the common supply flow path 18 and the supply connection flow path 323 is ejected from the ejection port 13 by driving the ejection element 15. When the ejection element 15 is not driven, the ink is recovered from the pressure chamber 12 to the common recovery flow path 19 via the recovery connection flow path 324, which is a recovery flow path.

[0103] In the case of using the serial type liquid ejection device 50, when ejecting ink from the circulating ink, the ejection of the ink is influenced by the ink oscillation in the ink flow path caused by the main scanning of the liquid ejection head 1. Specifically, the influence of the ink oscillation in the ink flow path may appear as a difference in the amount of ink ejected or a deviation in the ejection direction. As shown in FIG. 16, when the common supply flow path 18 and the common recovery flow path 19 have a cross-sectional shape that is wide in the X direction, which is the main scanning direction, the ink in the common supply flow path 18 and the common recovery flow path 19 is easily subjected to an inertial force in the main scanning direction, and the ink is greatly oscillated. As a result, there is a risk that the ink oscillation will affect the ejection of the ink from the ejection port 13. In addition, if the common supply flow path 18 and the common recovery flow path 19 are widened in the X direction, the distance between the colors will be increased, which may reduce the printing efficiency.

[0104] Therefore, the common supply flow path 18 and the common recovery flow path 19 of this embodiment extend in the Y direction in the cross section shown in FIG. 15, but are also configured to extend in the Z direction perpendicular to the X direction, which is the main scanning direction. With this configuration, the width of each flow path in the main scanning direction of the common supply flow path 18 and the common recovery flow path 19 can be reduced. By reducing the width of each flow path in the main scanning direction of the common supply flow path 18 and the common recovery flow path 19, the ink oscillation caused by the inertial force (indicated by the thick black arrow in the figure) acting on the ink in the common supply flow path 18 and the common recovery flow path 19 in the opposite direction to the main scanning direction during the main scanning is reduced. This makes it possible to suppress the effect of the ink oscillation on the ink ejection. In addition, the cross-sectional area is increased by extending the common supply flow path 18 and the common recovery flow path 19 in the Z direction, thereby reducing the flow path pressure loss.

[0105] As described above, by reducing the width of each of the common supply flow path 18 and the common recovery flow path 19 in the main scanning direction, the oscillation of ink in the common supply flow path 18 and the common recovery flow path 19 during main scanning is reduced, but the oscillation is not eliminated. Therefore, in order to suppress the occurrence of differences in ejection for each ink type that may still occur even with the reduced oscillation, in this embodiment, the common supply flow path 18 and the common recovery flow path 19 are configured to be disposed at positions that overlap with each other in the X direction.

[0106] As described above, in this embodiment, the supply connection flow path 323 and the recovery connection flow path 324 are provided corresponding to the ejection port 13, and the supply connection flow path 323 and the recovery connection flow path 324 are arranged side by side in the X direction with the ejection port 13 in between. Therefore, there are portions where the common supply flow path 18 and the common recovery flow path 19 do not overlap in the X direction, and if the corresponding relationship in the X direction between the supply connection flow path 323 and the recovery connection flow path 324 is lost, it will affect the flow and ejection of ink in the X direction in the pressure chamber 12. If the influence of ink fluctuation is added to this, it may further affect the ejection of ink from each ejection port.

[0107] Therefore, by arranging the common supply flow path 18 and the common recovery flow path 19 at positions where they overlap in the X direction, the ink oscillation during main scanning in the common supply flow path 18 and the common recovery flow path 19 becomes approximately equal at any position in the Y direction where the ejection ports 13 are arranged. As a result, the pressure difference between the common supply flow path 18 side and the common recovery flow path 19 side generated in the pressure chamber 12 does not vary greatly, and stable ejection can be performed.

[0108] In addition, in some liquid ejection heads that circulate ink, the flow path that supplies ink to the liquid ejection head and the flow path that recovers ink are configured as the same flow path, but in this embodiment, the common supply flow path 18 and the common recovery flow path 19 are configured as separate flow paths. The supply connection flow path 323 and the pressure chamber 12 are connected to each other, and the pressure chamber 12 and the recovery connection flow path 324 are connected to each other, and ink is ejected from the ejection port 13 of the pressure chamber 12. In other words, the pressure chamber 12, which is a path that connects the supply connection flow path 323 and the recovery connection flow path 324, is configured to have the ejection port 13. Therefore, an ink flow that flows from the supply connection flow path 323 side to the recovery connection flow path 324 side is generated in the pressure chamber 12, and the ink in the pressure chamber 12 is efficiently circulated. By efficiently circulating the ink in the pressure chamber 12, the ink in the pressure chamber 12, which is easily affected by the evaporation of ink from the ejection port 13, can be kept fresh.

[0109] Furthermore, since the two flow paths, the common supply flow path 18 and the common recovery flow path 19, are connected to the pressure chamber 12, if it becomes necessary to eject ink at a high flow rate, it is possible to supply ink from both flow paths. In other words, compared to a configuration in which ink supply and recovery are configured using only one flow path, the configuration of this embodiment has the advantage of not only being able to circulate ink efficiently, but also being able to handle ejection at a high flow rate.

[0110] Furthermore, the common supply flow path 18 and the common recovery flow path 19 are less susceptible to the influence of ink fluctuations when they are disposed close to each other in the X direction. It is preferable that the distance between the flow paths is 75 μm to 100 μm.

[0111] Fig. 17 is a diagram showing an ejection element substrate 340 as a comparative example. Note that in Fig. 17, the supply connection flow path 323 and the recovery connection flow path 324 are omitted. Since ink that has received thermal energy from the ejection elements 15 in the pressure chambers 12 flows into the common recovery flow path 19, ink with a relatively high temperature flows compared to the temperature of the ink in the common supply flow path 18. At this time, in the comparative example, there is a portion in the X direction of the ejection element substrate 340 where only the common recovery flow path 19 exists, such as the α portion surrounded by the dashed line in Fig. 17. In this case, the temperature locally increases in that portion, causing temperature unevenness in the ejection module 300, which may affect ejection.

[0112] In the common supply flow path 18, ink flows that is at a relatively low temperature relative to the common recovery flow path 19. Therefore, when the common supply flow path 18 and the common recovery flow path 19 are adjacent to each other, the temperatures in the common supply flow path 18 and the common recovery flow path 19 are partially offset in the vicinity thereof, suppressing a rise in temperature. Therefore, it is preferable that the common supply flow path 18 and the common recovery flow path 19 are adjacent to each other and have approximately the same length, and are positioned so as to overlap each other in the X direction.

[0113] 18(a) and (b) are diagrams showing the flow path configuration of the liquid ejection head 1 corresponding to three colors of ink: cyan (C), magenta (M), and yellow (Y). As shown in FIG. 18(a), the liquid ejection head 1 is provided with a circulation flow path for each type of ink. The pressure chambers 12 are provided along the X direction, which is the main scanning direction of the liquid ejection head 1. As shown in FIG. 18(b), the common supply flow path 18 and the common recovery flow path 19 are provided along the ejection port row in which the ejection ports 13 are arranged, and are provided extending in the Y direction so as to sandwich the ejection port row between the common supply flow path 18 and the common recovery flow path 19.

[0114] <Connection between the main body and the liquid ejection head> 19 is a schematic diagram showing in more detail the connection state between the ink tank 2 and external pump 21 provided in the main body of the liquid ejection device 50 of this embodiment and the liquid ejection head 1, and the arrangement of the circulation pump, etc. The liquid ejection device 50 of this embodiment has a configuration that allows the liquid ejection head 1 alone to be easily replaced when a malfunction occurs in the liquid ejection head 1. Specifically, it has a liquid connection part 700 that allows the ink supply tube 59 connected to the external pump 21 to be easily connected and disconnected from the liquid ejection head 1. This makes it possible to easily attach and detach only the liquid ejection head 1 to and from the liquid ejection device 50.

[0115] 19, the liquid connection part 700 has a liquid connector insertion port 53a protruding from the head housing 53 of the liquid ejection head 1, and a cylindrical liquid connector 59a into which the liquid connector insertion port 53a can be inserted. The liquid connector insertion port 53a is fluidly connected to an ink supply flow path formed in the liquid ejection head 1, and is connected to the first pressure adjustment means 120 via the above-mentioned filter 110. In addition, the liquid connector 59a is provided at the tip of an ink supply tube 59 connected to an external pump 21 that pressurizes and supplies ink from the ink tank 2 to the liquid ejection head 1.

[0116] 19, the liquid ejection head 1 can be easily attached, detached, and replaced by the liquid connection part 700. However, if the sealing performance between the liquid connector insertion port 53a and the liquid connector 59a is reduced, there is a risk that ink supplied under pressure by the external pump 21 will leak from the liquid connection part 700. If the leaked ink adheres to the circulation pump 500 or the like, a malfunction may occur in the electrical system. Therefore, in this embodiment, the circulation pump and the like are arranged as follows.

[0117] <Location of circulating pumps, etc.> As shown in FIG. 19, in this embodiment, in order to prevent ink leaking from the liquid connection part 700 from adhering to the circulation pump 500, the circulation pump 500 is disposed above the liquid connection part 700 in the direction of gravity. In other words, the circulation pump 500 is disposed above the liquid connector insertion port 53a, which is the liquid inlet port of the liquid ejection head 1, in the direction of gravity. Furthermore, the circulation pump 500 is disposed at a position where it is not in contact with the members constituting the liquid connection part 700. As a result, even if ink leaks from the liquid connection part 700, the ink flows in the horizontal direction, which is the opening direction of the liquid connector 59a, or downward in the direction of gravity, so that it is possible to prevent the ink from reaching the circulation pump 500, which is located above in the direction of gravity. In addition, since the circulation pump 500 is disposed at a position away from the liquid connection part 700, the possibility that the ink will reach the circulation pump 500 by running down the members is also reduced.

[0118] Furthermore, the electrical connection part 515, which electrically connects the circulation pump 500 and the electrical contact board 6 via a flexible wiring member 514, is provided above the liquid connection part 700 in the direction of gravity. This makes it possible to reduce the possibility of electrical trouble caused by ink from the liquid connection part 700.

[0119] Furthermore, in this embodiment, since the wall portion 52b of the head housing 53 is provided, even if ink is ejected from the opening 59b of the liquid connection portion 700, the ink can be blocked, reducing the possibility of the ink reaching the circulation pump 500 or the electrical connection portion 515.

[0120] <Backflow of ink near the ejection port> Next, the characteristic features of the present invention will be described below. FIG. 20 is a diagram showing a reverse flow of ink near the ejection port. FIG. 20(a) is a diagram showing a schematic diagram of the circulation path shown in FIG. 5, and FIG. 20(b) is an enlarged view of the ejection module shown in FIG. 3(b). In FIG. 5 and FIG. 3(b), the ink in the pressure chamber 12 flows in from the common supply flow path 18, passes through the pressure chamber 12, and flows out from the common recovery flow path 19. As described above, when recording at a high duty is continued, ink also flows back into the pressure chamber 12 from the recovery flow path 140 side. That is, as shown in FIG. 20, the pressure chamber 12 is refilled with ink from both the supply flow path 130 (common supply flow path 18) and the recovery flow path 140 (common recovery flow path 19). That is, the ink supplied from the first pressure control chamber 122 to the bypass flow path 160 is supplied to the second pressure control chamber 152 via the second valve chamber 151 of the second pressure adjustment means 150. Then, a portion of the ink supplied to the second pressure control chamber 152 is supplied to the recovery passage 140 and then to the ejection port 13 via the common recovery passage 19 .

[0121] FIG. 21 is a diagram for explaining the ink supply in the ejection module 300. FIG. 21(a) is a diagram showing a flow path configuration in the vicinity of the pressure chamber 12, and shows a comparative example different from this embodiment. In FIG. 21(a), only one side of the pressure chamber 12 is connected to the flow path 2010. In this configuration, ink is supplied to the pressure chamber 12 from only the flow path 2010, which is a one-sided supply. In the configuration of FIG. 21(a), the independent supply port 2020 communicating with the pressure chamber 12 is connected to the common supply flow path 18 or the common recovery flow path 19, or both. In particular, when a thermal type ejection element is used as the ejection element 15, ink is ejected from the ejection port 13 by foaming in the pressure chamber 12. In addition, ink is refilled in the pressure chamber 12 by the defoaming in response to this foaming. In such a flow path configuration, the width of the flow path 2010 connected to the pressure chamber 12 is narrowed or the length is increased to increase the rear resistance during foaming. This makes the bubbles more symmetrical, improving droplet formation. On the other hand, in the configuration shown in FIG. 21(a), when ink is refilled into the pressure chamber 12 when the bubbles disappear after ejection, the supply performance is reduced by increasing the rear resistance. Therefore, in the flow path configuration shown in FIG. 21(a), it is generally difficult to improve the refill frequency. In particular, when performing a printing operation at a high duty, the amount of ink supplied to the ejection port is reduced, and ejection stability may be reduced.

[0122] On the other hand, FIG. 21(b) is a diagram showing a flow path configuration in the vicinity of the pressure chamber 12 in this embodiment. The supply connection flow path 323, which is a first independent supply port, connects the first liquid flow path 2030 leading to the pressure chamber 12 with the common supply flow path 18. The recovery connection flow path 324, which is a second independent supply port, connects the second liquid flow path 2040 leading to the pressure chamber 12 with the common recovery flow path 19. As described above, in this embodiment, the ink ejected from the ejection port 13 is refilled from the first liquid flow path 2030 and the second liquid flow path 2040. As shown in FIG. 21(b), both sides of the pressure chamber 12 are connected to the first liquid flow path 2030 and the second liquid flow path 2040, forming a double-sided supply configuration. In this configuration, as shown in FIG. 21(b), even if the width of the flow path leading to the pressure chamber 12 is widened or the length is shortened, the bubbling tends to approach symmetry due to the symmetry of the rear resistance during bubbling. This makes it easier to improve the formation of ink droplets. Furthermore, since there is no need to increase the rear resistance when ink is refilled into the pressure chamber 12 when bubbles disappear after ejection, the ink supply can be improved. Thus, according to this embodiment, ejection stability can be improved even when recording is performed at a high duty. In other words, it is possible to achieve both improved droplet formation and an improved refill frequency.

[0123] In the above embodiment, the case where the thermal type ejection element is mainly used has been described, but the piezoelectric type ejection element may also be used. However, since the thermal type is more difficult to achieve both improved droplet formation and improved refill frequency, this embodiment is more suitable for the thermal type.

[0124] <Removal of air bubbles from inside the head> In a circulation type liquid ejection head as in this embodiment, the ink storage volume in the liquid ejection head is likely to be larger due to the ink recovery flow path and the pressure adjustment mechanism, etc., compared to a non-circulation type liquid ejection head. In addition, when the ink storage volume in the liquid ejection head is larger, the amount of remaining air bubbles when filling the liquid ejection head with ink is generally likely to be larger. Furthermore, if the amount of remaining air bubbles after filling is large, the amount of air bubbles that invade the liquid ejection head from the outside due to gas permeation as time passes is likely to be large. Furthermore, in the case of a temperature adjustment mechanism as in this embodiment, air bubbles dissolved in the ink are likely to precipitate as the temperature of the ink increases due to the temperature adjustment mechanism, which may result in a further increase in the amount of air bubbles in the liquid ejection head.

[0125] If air bubbles remaining in the liquid ejection head flow into the pressure chamber, sufficient pressure for ejection cannot be transmitted to the liquid in the pressure chamber during ejection, which may cause ejection defects. Furthermore, in this embodiment, a piezoelectric pump is provided as a circulation pump in the liquid ejection head, and when a piezoelectric pump is used, if air bubbles remaining in the liquid ejection head flow into the piezoelectric pump, the pressure in the pump chamber during pump operation changes. The change in pressure may cause the flow rate to change, and the change in the circulation flow rate may cause ejection defects. Therefore, it is important to efficiently remove air bubbles in the liquid ejection head.

[0126] First, the flow of ink and the operation of the first pressure adjustment means 120 and the second pressure adjustment means 150 when air bubbles are discharged from inside the liquid discharge head 1 in this embodiment will be described with reference to Fig. 20. Air bubbles BL that have entered the first pressure control chamber 122 and the second pressure control chamber 152 by gas permeation from the upstream side of the first pressure adjustment means 120, inside the circulation path, or from the outside of the liquid discharge head 1 tend to remain in the upper parts of the first pressure control chamber 122 and the second pressure control chamber 152 due to the influence of buoyancy. The air bubbles BL that have gathered in the upper parts of the first pressure control chamber 122 and the second pressure control chamber 152 can be discharged together with the ink by performing a suction process that forcibly sucks ink from the discharge port when the liquid discharge operation is not being performed.

[0127] The suction process is performed by tightly contacting a cap member to the ejection port surface of the liquid ejection head 1 where the ejection ports are formed, and applying negative pressure from a negative pressure source connected to the cap member to the ejection ports to forcibly suck ink from the ejection ports. The flow rate of ink generated in the flow path during this suction is faster than the flow rate of ink generated by normal ink ejection. Therefore, the air bubbles BL collected in the upper part of the first pressure control chamber 122 and the second pressure control chamber 152 reach the pressure chamber 12 together with the ink via the supply flow path 130 or the recovery flow path 140, and are then discharged together with the ink from the ejection port 13. This suction process is generally performed in a suction recovery process that is performed to recover ejection performance by discharging thickened ink generated in the ejection port or pressure chamber from the ejection port, or in an initial filling process that fills the flow path with ink.

[0128] The circulation path formed within the liquid ejection head 1 in this embodiment will be described in detail below.

[0129] Fig. 22 is a diagram showing a schematic diagram of a flow path configuration in the liquid ejection head 1 of this embodiment. Fig. 22 shows a state closer to the embodiment compared to Fig. 20. A first discharge flow path 801 and a second discharge flow path 802 are each connected to the first pressure control chamber 122, and the first discharge flow path 801 and the second discharge flow path 802 are connected to the supply flow path 130. The valve chamber supply port 807 is a supply port for ink from the liquid ejection device 50 to the first valve chamber 121. A first discharge port 803 is formed at the connection portion between the first discharge flow path 801 and the first pressure control chamber 122, and a second discharge port 804 is formed at the connection portion between the second discharge flow path 802 and the first pressure control chamber 122.

[0130] As described above, the air bubbles BL stored in the first pressure control chamber 122 rise to the top of the first pressure control chamber 122 and are collected there, so it is preferable that the first exhaust port 803 be located in the top of the first pressure control chamber 122, and more preferably connected to the upper end. On the other hand, it is preferable that the second exhaust port 804 be located in the lower part so that the air bubbles BL in the first pressure control chamber 122 are less likely to be exhausted.

[0131] Next, the displacement of the pressure plate 210 in this embodiment will be described. As shown in the above-mentioned formula 2, the flexible member 230 and the pressure plate 210 are displaced to the right in the figure in response to the pressure of the first pressure control chamber 122, and the pressure plate 210 abuts against the valve shaft 190a, opening the communication port 191. Even after the communication port 191 is opened, the pressure plate 210 is displaced according to formula 2. Considering the pressure loss in the flow of ink from the first valve chamber 121 through the communication port 191 to the first pressure control chamber 122, the faster the ink flow speed, the greater the pressure loss. Therefore, the pressure loss in the flow from the first valve chamber 121 to the first pressure control chamber 122 is represented by the differential pressure P1-P2 between the pressure P1 of the first valve chamber 121 and the pressure P2 of the first pressure control chamber 122, and increases as the ink flow speed increases. Therefore, when the ink flow speed increases with respect to a certain pressure P1, the pressure P2 decreases.

[0132] On the other hand, pressure P1 indicates the pressure of ink pressurized by the external pump 21 from the liquid ejection device 50 and supplied to the first valve chamber 121 via the filter 110. Therefore, with the same pump capacity, as the ink flow rate increases, pressure P1 decreases due to pressure loss in the ink flow path from the external pump 21 to the first valve chamber 121 and in the filter 110. As a result, as the ink flow rate increases, pressure P1 decreases, and further pressure loss increases in the flow of ink from the first valve chamber 121 through the communication port 191 to the first pressure control chamber 122, so pressure P2 decreases.

[0133] 7(a) to (c), the pressure plate 210 is displaced in response to the pressure P2 inside the first pressure control chamber 122. Therefore, as the ink flow velocity increases, the pressure P2 inside the first pressure control chamber 122 decreases. Then, the pressure plate 210 and the flexible member 230 are displaced against the biasing forces of the pressure adjustment spring 220 and the valve spring 200 in a direction in which the internal volume of the first pressure control chamber 122 decreases, i.e., to the right in FIG.

[0134] Next, the flow speed of ink in the first discharge flow path 801 and the second discharge flow path 802 in a state where a liquid ejection operation is being performed and a state where a suction process is being performed in this embodiment will be described. Fig. 22(a) shows a state where a liquid ejection operation is being performed, and Fig. 22(b) shows a schematic diagram of a state where a suction process is being performed. In both a state where a liquid ejection operation is being performed and a state where a suction process is being performed, the flow speed of ink flowing into the first pressure control chamber 122 is faster in the state where a suction process is being performed.

[0135] As shown in FIG. 22(a), when the liquid ejection operation is being performed, the pressure plate 210 is configured to be separated from the second stopper 805 and the first stopper 806. That is, the pressure plate 210 at the pressure P2 determined by the ink flow rate flowing into the first pressure control chamber 122 is separated from the second stopper 805 and the first stopper 806 by the biasing force of the pressure adjustment spring 220 and the valve spring 200 and the adjustment of the pressure receiving area of ​​the pressure plate 210. In this state, both the first discharge flow path 801 and the second discharge flow path 802 are in a state of communicating with the first pressure control chamber 122. Then, ink is discharged from each of the flow paths according to the flow resistance ratio between the flow path from the first pressure control chamber 122 through the first discharge flow path 801 to the supply flow path 130 and the flow path from the first pressure control chamber 122 through the second discharge flow path 802 to the supply flow path 130.

[0136] In this state, the air bubbles BL accumulated in the upper part of the first pressure control chamber 122 are made difficult to be discharged to the discharge module 300 via the first discharge flow path 801 and the supply flow path 130. For this reason, it is desirable to set the flow path resistance of the flow path from the first pressure control chamber 122 through the first discharge flow path 801 to the supply flow path 130 as large as possible, or to set the flow path resistance of the flow path from the first pressure control chamber 122 through the second discharge flow path 802 to the supply flow path 130 as small as possible.

[0137] Furthermore, in a state in which the suction operation is being performed, the pressure plate 210 is configured to come into contact with the second stopper 805 and the first stopper 806. In other words, the pressure plate 210 at pressure P2 determined by the flow speed of ink flowing into the first pressure control chamber 122 comes into contact with the second stopper 805 and the first stopper 806 by adjustment of the biasing forces of the pressure adjustment spring 220 and the valve spring 200 and the pressure-receiving area of ​​the pressure plate 210.

[0138] In this state, the first discharge flow path 801 is in communication with the first pressure control chamber 122, and the second discharge flow path 802 is in a non-communicating state with the first pressure control chamber 122, and ink is discharged from the first pressure control chamber 122 through the first discharge flow path 801 to the supply flow path 130. Therefore, during the suction process, the flow rate of ink discharged from the first pressure control chamber 122 through the first discharge flow path 801 becomes large. Therefore, the air bubbles BL stored in the first pressure control chamber 122 are discharged through the first discharge flow path 801 via the supply flow path 130 and finally from the discharge port to the outside of the liquid discharge head 1.

[0139] As a desirable example, the second discharge flow path 802 is not connected to the first pressure control chamber 122 while the suction operation is being performed, but the present invention is not limited to this. The ratio of the flow resistance of the flow path from the first pressure control chamber 122 through the second discharge flow path 802 to the supply flow path 130 to the flow resistance of the flow path from the first pressure control chamber 122 through the first discharge flow path 801 to the supply flow path 130 is made larger during the suction operation than during the liquid ejection operation. Even with this configuration (providing a flow resistance increasing means for increasing the flow resistance), a certain degree of effect can be obtained.

[0140] Furthermore, the flow rate of ink flowing from the first pressure control chamber 122 to the supply flow path 130 via the first discharge flow path 801 is set faster during the suction operation than during the liquid ejection operation, relative to the flow rate of ink flowing from the first pressure control chamber 122 to the supply flow path 130 via the second discharge flow path 802. Even with this configuration, it is possible to obtain a certain degree of effect.

[0141] 22, for example, if the distance between the pressure plate 210 and the first discharge port 803 in the displacement direction of the pressure plate 210 is distance L1, and the distance between the pressure plate 210 and the second discharge port 804 in the displacement direction of the pressure plate 210 is distance L2, then L1>L2. This makes the rate of change in flow resistance of this portion relative to the amount of displacement when the pressure plate 210 is displaced from a state in which a liquid ejection operation is being performed to a state in which a suction operation is being performed larger in the second discharge port. As a result, the flow resistance of the flow path connecting the first pressure control chamber 122 to the supply flow path 130 via the second discharge flow path 802 can be made larger during the suction operation than during the liquid ejection operation relative to the flow resistance of the flow path connecting the first pressure control chamber 122 to the supply flow path 130 via the first discharge flow path 801.

[0142] FIG. 23 is a front cross-sectional view of the first pressure control chamber 122 in this embodiment. The second stopper 805, the first stopper 806, and the first slit 808 in the first pressure control chamber 122 in this embodiment will be described below with reference to FIG. 23. The second stopper 805 is provided at two locations in the vertical upper portion of the first pressure control chamber 122, and the first stopper 806 is provided so as to surround the second exhaust port 804. When the pressure plate 210 is displaced while the suction operation is being performed, the pressure plate 210 comes into contact with the second stopper 805 and the first stopper 806. Therefore, the inclination of the pressure plate 210 in the displacement direction is restricted by three locations, the two second stoppers 805 and the first stopper 806, and the first stopper 806 and the pressure plate 210 can be maintained in a substantially parallel state. Therefore, the entire area of ​​the first stopper 806 is more likely to come into contact with the pressure plate 210, and the second discharge flow path 802 is more likely to be out of communication with the first pressure control chamber 122.

[0143] The first slit 808 has a concave shape to facilitate communication between the first pressure control chamber 122 and the first discharge flow path 801 when the pressure plate 210 is in contact with the second stopper 805 and the first stopper 806. The first slit 808 is disposed extending from the center of the first pressure control chamber 122 toward the first discharge port 803. Therefore, even when the pressure plate 210 is in contact with the second stopper 805 and the first stopper 806, the first pressure control chamber 122 and the first discharge flow path 801 can secure a constant flow path cross section defined by the first slit 808. Therefore, the flow resistance of the ink flow path from the first pressure control chamber 122 through the first discharge flow path 801 can be reduced, and a decrease in the ink flow rate of the first discharge flow path 801 can be suppressed.

[0144] 24 is a diagram showing a schematic configuration of a flow path in the liquid ejection head 1 of the present embodiment. Hereinafter, the third discharge flow path 809, the third discharge port 810, and the second slit 811 in the present embodiment will be described with reference to FIGS.

[0145] As shown in FIG. 24, the second pressure adjustment means 150 is also configured with a first discharge flow path 801 and a second discharge flow path 802, similar to the first pressure adjustment means 120. The third discharge flow path 809 is provided in the lower part of the first pressure control chamber 122, communicates with the third discharge port 810, and further communicates with the bypass flow path 160. Similarly to the above-mentioned first slit 808, a second slit 811 is arranged extending from the center of the first pressure control chamber 122 to the third discharge port 810. In a state where the suction process is being performed, even in a state where the pressure plate 210 is in contact with the second stopper 805 and the first stopper 806, the first pressure control chamber 122 and the third discharge flow path 809 can ensure a certain amount of flow path cross section defined by the second slit 811. Therefore, the flow resistance of the ink flow path from the first pressure control chamber 122 through the third discharge flow path 809 can be reduced, and the ink flow velocity of the third discharge flow path 809 can be ensured to be equal to or higher than a certain flow velocity.

[0146] For example, when a suction process such as an initial filling process for filling the flow path with ink is being performed, ink supplied from the liquid ejection device 50 to the first valve chamber 121 is supplied to the first pressure control chamber 122 via the communication port 191A. The ink supplied to the first pressure control chamber 122 fills the first pressure control chamber 122 from the vertically downward direction of the first pressure control chamber 122 due to gravity, so that the ink level in the first pressure control chamber 122 rises as the suction process progresses. At this time, the third discharge port 810 disposed vertically below the first pressure control chamber 122 is submerged in the ink level at an early stage when the first pressure control chamber 122 is filled. Therefore, ink is supplied from the third discharge flow path 809 to the second pressure control chamber 152 via the bypass flow path 160, the second valve chamber 151, and the communication port 191B.

[0147] When using choke suction as a suction process method for initial filling, the flow rate of ink discharged from the nozzle by suction is determined by the negative pressure of the negative pressure source connected to the cap member. However, this negative pressure value generally shifts to the positive pressure side over time after filling begins. Therefore, the flow rate of ink discharged from the nozzle slows down over time.

[0148] The air bubbles BL in the second pressure control chamber 152 are discharged to the recovery flow path 140 by the ink flow speed passing through the first discharge flow path 801 in a manner similar to that described using the first pressure adjustment means 120. Therefore, the faster the ink flow speed during discharge, the easier it is to discharge the air bubbles BL. Therefore, by supplying ink into the second pressure control chamber 152 at a relatively early stage after the start of filling, the air bubbles BL in the second pressure control chamber 152 are discharged while the ink flow speed is fast, improving the efficiency of air bubble discharge.

[0149] 25 is a graph showing the relationship between the flow resistance in the flow path connecting the first pressure control chamber 122 to the supply flow path 130 via the second discharge flow path 802 and the distance L2 in the displacement direction between the second discharge port 804 and the pressure plate 210. As shown in FIG. 25, in this embodiment, the flow resistance is configured to nonlinearly increase as the distance L2 between the second discharge port 804 and the pressure plate 210 decreases, and the flow resistance becomes extremely large when the pressure plate 210 abuts against the first stopper 806 of the second discharge port 804. As a result, the flow of ink via the second discharge flow path 802 is extremely reduced, and the air bubbles BL can be easily discharged by the flow of ink via the first discharge flow path 801.

[0150] In this way, the movement of the pressure plate 210 accompanying the reduction in the volume of the first pressure control chamber 122 increases the flow resistance of the flow path connected to the supply flow path 130 via the second discharge flow path 802 relative to the flow resistance of the flow path connected to the supply flow path 130 via the first discharge flow path 801. This makes it possible to provide a liquid ejection head and a liquid ejection device that can suppress the occurrence of ejection defects.

[0151] Second embodiment Hereinafter, a second embodiment of the present invention will be described with reference to the drawings. Note that since the basic configuration of this embodiment is similar to that of the first embodiment, the following will describe its characteristic configuration.

[0152] FIG. 26(a) is a diagram showing a schematic configuration of a flow path in the liquid ejection head 1 of this embodiment. In this embodiment, when the flow of ink flowing from the first valve chamber 121 to the first pressure control chamber 122 becomes faster than the flow speed in the liquid ejection operation, the pressure plate 210 moves with the reduction in the volume of the first pressure control chamber 122. Then, the pressure plate 210 abuts against the first stopper 806 and the second stopper 805 at almost the same timing. As a result, the first outlet 803 and the second outlet 804 are closed, and ink is not discharged through the first outlet 803 and the second outlet 804. However, in this embodiment, a bypass discharge flow path 900 connecting the first pressure control chamber 122 and the first discharge flow path 801 is provided near the first outlet 803. Therefore, even when the first outlet 803 is closed, ink can be discharged from the first pressure control chamber 122 to the first discharge flow path 801 through the bypass discharge flow path 900. The air bubbles BL can be easily discharged by the flow of ink via the bypass discharge flow path 900. If the connection position between the bypass discharge flow path 900 and the first discharge flow path 801 is located downstream of the air bubbles BL, the air bubbles BL cannot be discharged. Therefore, it is desirable to provide the connection position between the bypass discharge flow path 900 and the first discharge flow path 801 as close to the first discharge port 803 as possible on the upstream side.

[0153] (Third embodiment) Hereinafter, a third embodiment of the present invention will be described with reference to the drawings. Note that since the basic configuration of this embodiment is similar to that of the first embodiment, the following will describe its characteristic configuration.

[0154] FIG. 26(b) is a diagram showing a schematic diagram of a flow path configuration in the liquid ejection head 1 of this embodiment. In this embodiment, the pressure plate 210 is provided with a protrusion 901 at a position corresponding to the second outlet 804, and is configured so that when the pressure plate 210 moves with a decrease in the volume of the first pressure control chamber 122, the protrusion 901 blocks the second outlet 804. During liquid ejection operation, the protrusion 901 is separated from the second outlet 804, so that the liquid is ejected through the second outlet 804, but when the flow of the liquid from the first valve chamber 121 to the first pressure control chamber 122 becomes faster due to the suction operation, the protrusion 901 blocks the second outlet 804. When the second outlet 804 is blocked by the protrusion 901, the flow resistance of the flow path connected to the supply flow path 130 through the second exhaust flow path 802 increases. This makes it possible to extremely reduce the flow of ink via the second discharge flow path 802, and to easily discharge the air bubbles BL by the flow of ink via the first discharge flow path 801.

[0155] The shape of the protrusion 901 is not limited to that shown in Fig. 26(b). Any shape may be used as long as the flow resistance of the flow path connected to the supply flow path 130 via the second discharge flow path 802 increases with the movement of the pressure plate 210. For example, the protrusion 901 may be in a conical shape whose cross-sectional area gradually decreases in the direction of movement of the pressure plate 210 so that the flow resistance increases as the tip of the protrusion 901 enters the second discharge port 804 with the movement of the pressure plate 210.

[0156] (Fourth embodiment) Hereinafter, a fourth embodiment of the present invention will be described with reference to the drawings. Note that since the basic configuration of this embodiment is similar to that of the first embodiment, the following will describe its characteristic configuration.

[0157] FIG. 26(c) is a diagram showing a schematic configuration of a flow path in the liquid ejection head 1 of this embodiment. In this embodiment, as in each of the above embodiments, the first pressure control chamber 122 is covered by the pressure plate 210 and the flexible member, but in this embodiment, the area covered by the pressure plate 210 is small, and the area covered by the flexible member 902 is large. When the pressure plate 210 moves with the reduction in the volume of the first pressure control chamber 122, the second discharge port 804 is covered and closed by the flexible member 902. The second discharge port 804 is blocked by the flexible member 902, so that the flow resistance of the flow path connected to the supply flow path 130 via the second discharge flow path 802 is increased. This makes it possible to greatly reduce the flow of ink via the second discharge flow path 802, and to easily discharge the air bubbles BL by the flow of ink via the first discharge flow path 801.

[0158] Fifth embodiment Hereinafter, the fifth embodiment of the present invention will be described with reference to the drawings. Note that since the basic configuration of this embodiment is similar to that of the first embodiment, the following will describe its characteristic configuration.

[0159] 26(d) is a diagram showing a schematic diagram of a flow path configuration in the liquid ejection head 1 of this embodiment. The flow path configuration of this embodiment is a configuration in which the diameter of the second outlet 804 is smaller than the diameter of the first outlet 803 in the configuration of the first embodiment. That is, when the distance between the pressure plate 210 and the first outlet 803 in the displacement direction of the pressure plate 210 is distance L1, and the distance between the pressure plate 210 and the second outlet 804 in the displacement direction of the pressure plate 210 is distance L2, L1>L2 is satisfied. Furthermore, the diameter of the second outlet 804 is smaller than the diameter of the first outlet 803.

[0160] In this way, by making the diameter of the second outlet 804 smaller than the diameter of the first outlet 803, the flow rate of ink in the flow path 905 connecting the second outlet 804 to the second outlet flow path 802 increases with the movement of the pressure plate 210 accompanying the reduction in the volume of the first pressure control chamber 122. When the ink flow rate increases, the flow resistance in the flow path 905 increases in proportion to the square of the flow rate. As a result, the flow of ink through the second outlet flow path 802 is extremely reduced, and the air bubbles BL can be easily discharged by the flow of ink through the first outlet flow path 801.

[0161] Sixth embodiment Hereinafter, the sixth embodiment of the present invention will be described with reference to the drawings. Note that since the basic configuration of this embodiment is similar to that of the first embodiment, the following will describe its characteristic configuration.

[0162] FIG. 26(e) is a diagram showing a schematic diagram of a flow path configuration in the liquid ejection head 1 of this embodiment. In this embodiment, a valve 903 is provided at a first outlet 803 that connects from the first pressure control chamber 122 to a first discharge flow path 801. When the pressure plate 210 moves with a decrease in the volume of the first pressure control chamber 122, the valve 903 opens, and the first pressure control chamber 122 and the first discharge flow path 801 communicate with each other. When the valve 903 is in a completely open state, the pressure plate 210 abuts against the second outlet 804, and the second discharge flow path 802 is not in communication with the first pressure control chamber 122. This increases the flow resistance of the flow path that connects to the supply flow path 130 via the second discharge flow path 802, and the air bubbles BL can be easily discharged by the flow of ink via the first discharge flow path 801.

[0163] Seventh embodiment Hereinafter, the seventh embodiment of the present invention will be described with reference to the drawings. Note that since the basic configuration of this embodiment is similar to that of the first embodiment, the following will describe its characteristic configuration.

[0164] FIG. 26(f) is a diagram showing a schematic diagram of a flow path configuration in the liquid ejection head 1 of this embodiment. In this embodiment, the pressure plate 210 is not provided, and instead an elastic thin film 904 is provided. When the ink flow speed increases, the elastic thin film 904 is displaced with a decrease in pressure P1, and the volume of the first pressure control chamber 122 decreases. Due to the displacement of the elastic thin film 904, the second discharge port 804 comes into contact with the elastic thin film 904, and the second discharge flow path 802 is not in communication with the first pressure control chamber 122. At this time, the first discharge port 803 connected to the first discharge flow path 801 does not come into contact with the elastic thin film 904, and the first discharge flow path 801 is in communication with the first pressure control chamber 122. As a result, the flow of ink through the second discharge flow path 802 is extremely reduced, and the air bubbles BL can be easily discharged by the flow of ink through the first discharge flow path 801.

[0165] The above-described embodiments may be combined as appropriate as possible. For example, the third embodiment (see FIG. 26(b)) and the seventh embodiment (see FIG. 26(f)) may be combined to form a protrusion 901 on an elastic thin film 904.

[0166] <<Modifications>> Next, various modified examples of the above-mentioned embodiment will be described. The configuration in which ink flows back from the recovery flow path 140 toward the pressure chamber 12 only needs to include a bypass flow path 160, and no mechanism that functions as a check valve needs to be provided between the pressure chamber 12 and the junction of the bypass flow path 160 and the recovery flow path 140 as described above. In this embodiment, since the circulation pump 500 is a pump that pumps liquid in one direction as described above, it is only necessary that the junction of the bypass flow path 160 is provided upstream of the circulation pump 500.

[0167] <First Modification> 27 and 28 are diagrams showing the circulation path in the first modified example. Fig. 27 shows the circulation path when circulation is performed without ejection. Fig. 28 shows the circulation path when high duty recording is performed. The first modified example shows an example in which the second pressure adjustment means 150 is not provided, and the bypass flow path 160 and the recovery flow path 140 are directly connected.

[0168] In this embodiment, the flow resistance of the flow path through the bypass flow path 160 to the recovery flow path 140 is R1, and the flow resistance of the flow path from the supply flow path 130 to the recovery flow path 140 through the ejection module 300 is R2. Since the amount of ink flowing through each is the inverse ratio of the resistance, the ratio of the flow rate of the flow path through the bypass flow path 160 to the flow rate of the flow path through the ejection module 300 is R2 to R1. According to this relationship, each flow resistance is set so that the circulation amount is capable of suppressing the thickening of ink near the ejection port 15 in the ejection module 300. In other words, the flow resistance R1 of the bypass flow path 160, which sets each flow resistance so that the flow velocity of the liquid in the pressure chamber is equal to or higher than a predetermined value, is controlled by changing the flow path cross-sectional area or flow path length, or by providing a throttle.

[0169] In the first modified example, when a recording operation is performed at a high duty, as shown in Fig. 28, the pressure chamber 12 is supplied from both sides. That is, the ink supplied from the first pressure control chamber 122 to the supply flow path 130 is supplied to the ejection port 13 via the common supply flow path 18 of the ejection module 300. On the other hand, a part of the ink supplied from the first pressure control chamber 122 to the bypass flow path 160 is supplied to the first pressure control chamber 122 via the circulation pump 500 and the pump outlet flow path 180. In addition, a part of the ink supplied to the bypass flow path 160 is supplied to the recovery flow path 140 and is supplied to the ejection port 13 via the common recovery flow path 19 of the ejection module 300. Therefore, the ink ejected from the ejection port 13 is supplied from both the supply flow path 130 and the recovery flow path 140.

[0170] <Second Modification> 29 and 30 are diagrams showing the circulation path in the second modified example. Fig. 29 shows the circulation path when circulation is performed without ejection. Fig. 30 shows the circulation path when high duty recording is performed. The second modified example shows an example in which the second pressure adjustment means 150 is not provided, the bypass flow path 160 and the recovery flow path 140 are directly connected, and a relief valve 2301 is provided in the bypass flow path 160.

[0171] The relief valve 2301 is configured so that ink flows from the upstream side to the downstream side of the relief valve when the pressure on the downstream side of the relief valve becomes equal to or lower than a certain value. That is, the relief valve is configured to open when the pressure on the recovery flow path side becomes lower than the supply flow path side by a predetermined amount. The flow of ink supply is basically the same as the configuration in which the second pressure adjustment means 150 is arranged as shown in FIG. 5 and FIG. 20. The amount of ink circulating in the ejection module 300 is determined by the difference in the control pressure between the first pressure control chamber 122 and the relief valve 2301. The control pressure of the relief valve 2301 is set so as to obtain an amount of ink circulating that can suppress thickening of the ink near the ejection port 15 in the ejection module 300.

[0172] In the second modified embodiment, when a recording operation is performed at a high duty, as shown in FIG. 30, the pressure chamber 12 is supplied from both sides. That is, the ink supplied from the first pressure control chamber 122 to the supply flow path 130 is supplied to the ejection port 13 via the common supply flow path 18 of the ejection module 300. On the other hand, a part of the ink supplied from the first pressure control chamber 122 to the bypass flow path 160 passes through the relief valve 2301 and is supplied to the first pressure control chamber 122 via the circulation pump 500 and the pump outlet flow path 180. In addition, a part of the ink supplied to the bypass flow path 160 passes through the relief valve 2301 and is supplied to the recovery flow path 140, and is supplied to the ejection port 13 via the common recovery flow path 19 of the ejection module 300. Therefore, the ink ejected from the ejection port 13 is supplied from both the supply flow path 130 and the recovery flow path 140.

[0173] <Third Modification> Next, various modified examples of the circulation flow path will be collectively described as the third modified example. As described above, the configuration in which ink flows back from the recovery flow path 140 toward the pressure chamber 12 only requires that the bypass flow path 160 is provided, and that no mechanism that functions as a check valve is provided between the junction of the bypass flow path 160 and the pressure chamber 12. Therefore, if the circulation flow path can maintain this relationship, ink can be supplied to both sides of the pressure chamber 12, thereby improving the ejection stability.

[0174] Fig. 31 is a block diagram showing a schematic diagram of a circulation path. Fig. 31 shows an example in which the pump outlet flow path 180 located downstream of the circulation pump 500 is configured to be connected to the ink tank 2, not to the first pressure control chamber 122. With this configuration as well, ejection stability can be improved, similar to the configurations described so far.

[0175] Fig. 32 is a block diagram showing a schematic diagram of a circulation path. Fig. 32 shows an example in which a circulation pump 500 that is mounted inside the liquid ejection head 1 is installed on the main body side of the liquid ejection device 50. A part of the pump inlet flow path 170 and the pump outlet flow path 180 are also arranged outside the liquid ejection head 1. With this configuration as well, ejection stability can be improved, similarly to the configurations described so far.

[0176] Fig. 33 is a block diagram showing a schematic diagram of a circulation path. Fig. 33 shows an example in which a circulation pump 500 mounted in a liquid ejection head 1 is installed on the main body side of a liquid ejection device 50, and a pump outlet flow path 180 is connected to an ink tank 2. With this configuration as well, ejection stability can be improved, similarly to the configurations described so far.

[0177] <Fourth Modification> 34 is a diagram showing a schematic diagram of a circulation path in the fourth modified example. The fourth modified example is an example in which the first pressure adjustment means 120 is provided with a first discharge flow path 801 that communicates the first pressure control chamber 122 and the supply flow path 130, but the second pressure adjustment means 150 is not provided with a flow path that communicates the second pressure control chamber 152 and the recovery flow path 140. Note that the first pressure adjustment means 120 may not be provided with a flow path that communicates the first pressure control chamber 122 and the supply flow path 130, and the second pressure adjustment means 150 may be provided with a flow path that communicates the second pressure control chamber 152 and the recovery flow path 140. In other words, a flow path that communicates the pressure control chamber and the supply flow path (recovery flow path) may be provided in either one of the first pressure adjustment means 120 or the second pressure adjustment means 150.

[0178] By configuring in this manner, it is possible to make it easier to expel air bubbles BL collected above the pressure control chamber in at least one of the first pressure adjustment means 120 and the second pressure adjustment means 150, thereby improving ejection stability.

[0179] <Fifth Modification> 1(a) is a so-called serial type liquid ejection head that ejects ink while moving in the main scanning direction, but is not limited to this. It may be a so-called full-line type liquid ejection head in which ejection ports are formed across the entire width of the recording medium P and ejection is possible across the entire width of the recording medium P without movement in the main scanning direction.

[0180] The disclosure of this embodiment includes the following configuration.

[0181] (Configuration 1) A discharge port for discharging liquid; an ejection element for generating pressure for ejecting liquid from the ejection port; a pressure chamber in which the ejection element is provided and which communicates with the ejection port; a first pressure adjusting means capable of changing a volume in response to a pressure of the liquid and adjusting the pressure of the liquid, a first flow path connecting the first pressure adjustment means and the pressure chamber; a first exhaust port provided at an upper portion of the first pressure adjustment means in a vertical direction; a first discharge flow path connecting the first discharge port and the first flow path; a second outlet provided in the first pressure adjustment means; a second discharge flow path connecting the second discharge port and the first flow path; Further comprising: When the volume of the first pressure adjusting means is decreased, a flow resistance increasing means for increasing the flow resistance in a flow path that flows liquid from the first pressure adjustment means through the second outlet and the second discharge flow path to the first flow path, relative to the flow resistance in a flow path that flows liquid from the first pressure adjustment means through the first outlet and the first discharge flow path to the first flow path.

[0182] (Configuration 2) a pump means capable of pumping liquid to the first pressure adjusting means; a second flow path connecting the pump means and the pressure chamber; a bypass flow path connecting the first pressure adjustment means and the second flow path; 2. The liquid ejection head according to configuration 1, further comprising:

[0183] (Configuration 3) provided in the second flow path between the pump means and the pressure chamber, a second pressure adjusting means that is connected to the first pressure adjusting means via the pump means and adjusts the pressure of the liquid; 3. The liquid ejection head according to configuration 2, wherein the first pressure adjustment means has a higher controlled pressure than the second pressure adjustment means.

[0184] (Configuration 4) a third outlet provided at an upper portion in a vertical direction of the second pressure adjustment means; a third discharge flow path connecting the third discharge port and the second flow path; a fourth outlet provided in the second pressure adjustment means; a fourth discharge flow path connecting the fourth discharge port and the second flow path; 4. The liquid ejection head according to configuration 3, further comprising:

[0185] (Configuration 5) the first pressure adjustment means comprises a first valve chamber, a first pressure control chamber whose volume is variable, a first opening which connects the first valve chamber and the first pressure control chamber, first valve means configured to open and close the first opening, and a first pressure plate which is displaced in accordance with a change in volume of the first pressure control chamber, the first pressure control chamber has a first pressure plate, a surface of which is formed by a first flexible member that is displaceable, and which is displaceable in conjunction with the first flexible member; and a first biasing member that biases the first pressure plate in a direction that increases the volume of the first pressure control chamber, the second pressure adjustment means has a second valve chamber, a second pressure control chamber whose volume is variable, a second opening which connects the second valve chamber and the second pressure control chamber, second valve means configured to open and close the second opening, and a second pressure plate which is displaced in accordance with a change in volume of the second pressure control chamber, the second pressure control chamber has a second pressure plate, a surface of which is formed by a second flexible member that is displaceable, and which is displaceable in conjunction with the second flexible member; and a second biasing member that biases the second pressure plate in a direction that increases the volume of the second pressure control chamber, opening and closing the first valve means in response to displacement of the first pressure plate and the first flexible member; 5. The liquid ejection head according to configuration 3 or 4, wherein the second valve means is opened or closed in response to displacement of the second pressure plate and the second flexible member.

[0186] (Configuration 6) 6. The liquid ejection head according to configuration 5, wherein the bypass flow path is connected to the first pressure control chamber in the first pressure adjustment means.

[0187] (Configuration 7) 7. The liquid ejection head according to configuration 5 or 6, wherein the bypass flow path is connected to the second valve chamber in the second pressure adjustment means.

[0188] (Configuration 8) 8. The liquid ejection head according to any one of configurations 5 to 7, wherein the second pressure control chamber in the second pressure adjustment means is connected to the pump means via the second flow path.

[0189] (Configuration 9) A liquid ejection head described in any one of configurations 5 to 8, characterized in that the flow resistance increasing means is configured to make the distance between the first pressure plate and the second exhaust port in the displacement direction of the first pressure plate shorter than the distance between the first pressure plate and the first exhaust port in the displacement direction of the first pressure plate.

[0190] (Configuration 10) Further, a first stopper is provided so as to surround the second outlet, A liquid ejection head described in any one of configurations 5 to 9, characterized in that when the first pressure plate is displaced in a direction in which the volume of the first pressure control chamber decreases, the first pressure plate comes into contact with at least a portion of the first stopper.

[0191] (Configuration 11) The liquid ejection head described in configuration 10, further comprising one or more second stoppers within the first pressure control chamber, wherein when the first pressure plate is displaced in a direction in which the volume of the first pressure control chamber decreases, at least a portion of the first pressure plate and the first stopper, and at least a portion of the first pressure plate and the second stopper come into contact with each other.

[0192] (Configuration 12) A liquid ejection head described in any one of configurations 5 to 11, further comprising a first slit formed in a concave shape within the first pressure control chamber, one end of the first slit being connected to the first exhaust port.

[0193] (Configuration 13) the first pressure adjustment means further includes a third outlet at a connection between the bypass flow path and the first pressure control chamber, 7. The liquid ejection head according to configuration 6, wherein the third outlet is located at least lower than the first outlet in the vertical direction.

[0194] (Configuration 14) The liquid ejection head described in configuration 13, further comprising a second slit formed in a concave shape within the first pressure control chamber, one end of the second slit being connected to the third outlet.

[0195] (Configuration 15) 15. The liquid ejection head according to any one of configurations 1 to 14, further comprising a supply flow path for supplying liquid from the outside to the first pressure adjustment means.

[0196] (Configuration 16) the flow resistance increasing means is a bypass discharge flow path provided in the vicinity of the first discharge port, The liquid ejection head of any one of configurations 5 to 8, characterized in that when the first pressure plate is displaced, the first pressure plate comes into contact with the first exhaust port, and the first pressure plate comes into contact with the second exhaust port.

[0197] (Configuration 17) the flow resistance increasing means is configured to make a distance between the first pressure plate and the second discharge port in a displacement direction of the first pressure plate shorter than a distance between the first pressure plate and the first discharge port in a displacement direction of the first pressure plate, A liquid ejection head described in any one of configurations 5 to 8, characterized in that the first pressure plate has a protrusion portion, and when the first pressure plate is displaced, the protrusion portion blocks the second discharge port.

[0198] (Configuration 18) 18. A liquid ejection head according to configuration 17, wherein the protrusion has a shape whose cross-sectional area gradually decreases in the direction of displacement of the first pressure plate.

[0199] (Configuration 19) the flow resistance increasing means is configured to make a distance between the first pressure plate and the second discharge port in a displacement direction of the first pressure plate shorter than a distance between the first pressure plate and the first discharge port in a displacement direction of the first pressure plate, The liquid ejection head according to any one of configurations 5 to 8, wherein when the first pressure plate is displaced, the second discharge port is blocked by the first flexible member.

[0200] (Configuration 20) the flow resistance increasing means is configured to make a distance between the first pressure plate and the second discharge port in a displacement direction of the first pressure plate shorter than a distance between the first pressure plate and the first discharge port in a displacement direction of the first pressure plate, The liquid ejection head according to any one of configurations 5 to 8, wherein the second outlet has a smaller diameter than the first outlet.

[0201] (Configuration 21) the flow resistance increasing means is configured to make a distance between the first pressure plate and the second discharge port in a displacement direction of the first pressure plate shorter than a distance between the first pressure plate and the first discharge port in a displacement direction of the first pressure plate, The liquid ejection head according to any one of configurations 5 to 8, wherein the first outlet is provided with a valve capable of opening and closing the first outlet.

[0202] (Configuration 22) the first pressure adjustment means has a valve chamber, a pressure control chamber whose volume is variable, an opening that connects the valve chamber and the pressure control chamber, a valve means configured to open and close the opening, and a flexible member that is displaced in accordance with a change in the volume of the pressure control chamber, the flow resistance increasing means is configured to make a distance between the flexible member and the second outlet in the displacement direction of the flexible member shorter than a distance between the flexible member and the first outlet in the displacement direction of the flexible member, The liquid ejection head according to configuration 1, wherein the second outlet is blocked by the flexible member.

[0203] (Configuration 23) A discharge port for discharging liquid; an ejection element for generating pressure for ejecting liquid from the ejection port; a pressure chamber in which the ejection element is provided and which communicates with the ejection port; a first pressure adjusting means capable of changing a volume in response to the pressure of the liquid and adjusting the pressure of the liquid; a pressure plate that is displaced in accordance with a change in volume of the first pressure adjustment means; A liquid ejection head comprising: a first flow path connecting the first pressure adjustment means and the pressure chamber; a first exhaust port provided at an upper portion of the first pressure adjustment means in a vertical direction; a first discharge flow path connecting the first discharge port and the first flow path; a second outlet provided in the first pressure adjustment means; a second discharge flow path connecting the second discharge port and the first flow path; Further comprising: While the pressure plate is displaced in a direction in which the volume of the first pressure adjustment means is decreased, a liquid ejection head, wherein a distance between the first ejection port and the pressure plate in a displacement direction of the pressure plate is longer than a distance between the second ejection port and the pressure plate in the displacement direction of the pressure plate.

[0204] (Configuration 24) A discharge port for discharging liquid; an ejection element for generating pressure for ejecting liquid from the ejection port; a pressure chamber in which the ejection element is provided and which communicates with the ejection port; A liquid ejection device capable of mounting a liquid ejection head including a first pressure adjustment means capable of changing a volume in response to a pressure of the liquid and adjusting the pressure of the liquid, a first flow path connecting the first pressure adjustment means and the pressure chamber; a first exhaust port provided at an upper portion of the first pressure adjustment means in a vertical direction; a first discharge flow path connecting the first discharge port and the first flow path; a second outlet provided in the first pressure adjustment means; a second discharge flow path connecting the second discharge port and the first flow path; Further comprising: When the volume of the first pressure adjusting means is decreased, a flow resistance increasing means for increasing the flow resistance in a flow path that flows liquid from the first pressure adjustment means through the second outlet and the second discharge flow path to the first flow path, relative to the flow resistance in the flow path that flows liquid from the first pressure adjustment means through the first outlet and the first discharge flow path to the first flow path. [Explanation of symbols]

[0205] 1 Liquid ejection head 120 First pressure adjustment means 122 First Pressure Control Room 130 Supply Channel 140 Recovery channel 150 Second pressure adjusting means 152 Second Pressure Control Room 210 Pressure Plate 500 Circulation Pump 801 First discharge flow path 802 Second discharge flow path 803 1st outlet 804 2nd outlet BL Bubbles

Claims

1. A nozzle for dispensing liquid, A discharge element for generating pressure to discharge liquid from the discharge port, The discharge element is provided in a pressure chamber that communicates with the discharge port, A liquid discharge head that can change its volume according to the liquid pressure and comprises a first pressure adjustment means for adjusting the liquid pressure, A first flow path connecting the first pressure regulating means and the pressure chamber, A first discharge port is provided at the upper part of the first pressure adjustment means in the vertical direction, A first discharge channel connecting the first discharge port and the first flow path, The second outlet provided in the first pressure adjustment means, A second discharge channel connecting the second discharge port and the first flow channel, Furthermore, When the volume of the first pressure regulating means decreases, A liquid discharge head characterized by comprising a flow resistance increasing means for increasing the flow resistance in the flow path through which liquid flows from the first pressure adjusting means to the first discharge port and the second discharge flow path, with respect to the flow resistance in the flow path through which liquid flows from the first pressure adjusting means to the first discharge port and the first discharge flow path, into the first flow path.

2. A pump means capable of supplying liquid to the first pressure adjusting means, A second flow path connecting the pump means and the pressure chamber, A bypass channel connecting the first pressure regulating means and the second flow path, The liquid dispensing head according to claim 1, further comprising the above.

3. The second flow path between the pump means and the pressure chamber is provided, The volume can be changed according to the pressure of the liquid, and the system further comprises a second pressure adjusting means connected to the first pressure adjusting means via the pump means for adjusting the pressure of the liquid, The liquid discharge head according to claim 2, characterized in that the first pressure adjustment means has a higher control pressure than the second pressure adjustment means.

4. A third discharge port is provided at the upper part of the second pressure adjustment means in the vertical direction, A third discharge channel connecting the third discharge port and the second flow channel, The fourth outlet provided in the second pressure adjustment means, A fourth discharge channel connecting the fourth discharge port and the second flow channel, The liquid dispensing head according to claim 3, further comprising the above.

5. The first pressure regulating means includes a first valve chamber, a first pressure control chamber whose volume can be changed, a first opening that connects the first valve chamber and the first pressure control chamber, a first valve means configured to open and close the first opening, and a first pressure plate that is displaced in accordance with the change in volume of the first pressure control chamber. The first pressure control chamber has a first pressure plate whose surface is formed by a first flexible member configured to be displaceable, and which is displaceable in conjunction with the first flexible member, and a first biasing member which biases the first pressure plate in a direction that increases the volume of the first pressure control chamber. The second pressure regulating means includes a second valve chamber, a second pressure control chamber whose volume can be changed, a second opening that connects the second valve chamber and the second pressure control chamber, a second valve means configured to open and close the second opening, and a second pressure plate that is displaced in accordance with the change in volume of the second pressure control chamber. The second pressure control chamber has a second pressure plate whose surface is formed by a second flexible member configured to be displaceable, and which is displaceable in conjunction with the second flexible member, and a second biasing member which biases the second pressure plate in a direction that increases the volume of the second pressure control chamber. The first valve means is opened and closed in accordance with the displacement of the first pressure plate and the first flexible member. The liquid discharge head according to claim 3, characterized in that the second valve means is opened and closed in accordance with the displacement of the second pressure plate and the second flexible member.

6. The liquid discharge head according to claim 5, characterized in that the bypass channel is connected to the first pressure control chamber in the first pressure adjustment means.

7. The liquid discharge head according to claim 5, characterized in that the bypass channel is connected to the second valve chamber in the second pressure regulating means.

8. The liquid discharge head according to claim 5, characterized in that the second pressure control chamber in the second pressure adjustment means is connected to the pump means via the second flow path.

9. The liquid discharge head according to claim 5, characterized in that the flow resistance increasing means is configured such that the distance between the first pressure plate and the second discharge port is shorter than the distance between the first pressure plate and the first discharge port in the displacement direction of the first pressure plate.

10. The device further comprises a first stopper formed to surround the second discharge port, The liquid discharge head according to claim 5, characterized in that when the first pressure plate is displaced in a direction that reduces the volume of the first pressure control chamber, the first pressure plate and at least a part of the first stopper come into contact.

11. The liquid discharge head according to claim 10, further comprising one or more second stoppers in the first pressure control chamber, wherein at least a portion of the first pressure plate and the first stopper, and at least a portion of the first pressure plate and the second stopper come into contact when the first pressure plate is displaced in a direction that reduces the volume of the first pressure control chamber.

12. The liquid discharge head according to claim 5, further comprising a first slit formed in a concave shape within the first pressure control chamber, wherein one end of the first slit is connected to the first discharge port.

13. The first pressure regulating means further includes a third outlet at the connection point between the bypass passage and the first pressure control chamber. The liquid discharge head according to claim 6, characterized in that the third discharge port is located at least lower in the vertical direction than the first discharge port.

14. The liquid discharge head according to claim 13, further comprising a first slit formed in a concave shape and a second slit formed in a concave shape within the first pressure control chamber, wherein one end of the second slit is connected to the third discharge port.

15. The liquid discharge head according to claim 1, further comprising a supply channel for supplying liquid to the first pressure adjustment means from an external source.

16. The flow resistance increasing means is a bypass discharge channel provided near the first discharge port, The liquid discharge head according to claim 5, characterized in that when the first pressure plate is displaced, the first pressure plate and the first discharge port come into contact, and the first pressure plate and the second discharge port come into contact.

17. The flow resistance increasing means is configured such that the distance between the first pressure plate and the second outlet in the displacement direction of the first pressure plate is shorter than the distance between the first pressure plate and the first outlet in the displacement direction of the first pressure plate. The liquid discharge head according to claim 5, characterized in that the first pressure plate is provided with a projection, and when the first pressure plate is displaced, the projection blocks the second discharge port.

18. The liquid discharge head according to claim 17, characterized in that the projection has a shape in which the cross-sectional area gradually decreases in the direction of displacement of the first pressure plate.

19. The flow resistance increasing means is configured such that the distance between the first pressure plate and the second outlet in the displacement direction of the first pressure plate is shorter than the distance between the first pressure plate and the first outlet in the displacement direction of the first pressure plate. The liquid discharge head according to claim 5, characterized in that the second discharge port is blocked by the first flexible member when the first pressure plate is displaced.

20. The flow resistance increasing means is configured such that the distance between the first pressure plate and the second outlet in the displacement direction of the first pressure plate is shorter than the distance between the first pressure plate and the first outlet in the displacement direction of the first pressure plate. The liquid discharge head according to claim 5, characterized in that the diameter of the second discharge port is smaller than the diameter of the first discharge port.

21. The flow resistance increasing means is configured such that the distance between the first pressure plate and the second outlet in the displacement direction of the first pressure plate is shorter than the distance between the first pressure plate and the first outlet in the displacement direction of the first pressure plate. The liquid discharge head according to claim 5, characterized in that the first discharge port is provided with a valve capable of opening and closing the first discharge port.

22. The first pressure regulating means includes a valve chamber, a pressure control chamber whose volume can be changed, an opening that connects the valve chamber and the pressure control chamber, a valve means configured to open and close the opening, and a flexible member that is displaced in accordance with the change in volume of the pressure control chamber. The flow resistance increasing means is configured such that the distance between the flexible member and the second outlet in the direction of displacement of the flexible member is shorter than the distance between the flexible member and the first outlet in the direction of displacement of the flexible member. The liquid discharge head according to claim 1, characterized in that the second discharge port is blocked with the flexible member.

23. A nozzle for dispensing liquid, A discharge element for generating pressure to discharge liquid from the discharge port, The discharge element is provided in a pressure chamber that communicates with the discharge port, The volume can be changed according to the liquid pressure, and a first pressure adjustment means for adjusting the liquid pressure, A pressure plate that is displaced in accordance with the change in volume of the first pressure adjustment means, A liquid dispensing head equipped with, A first flow path connecting the first pressure regulating means and the pressure chamber, A first discharge port is provided at the upper part of the first pressure adjustment means in the vertical direction, A first discharge channel connecting the first discharge port and the first flow path, The second outlet provided in the first pressure adjustment means, A second discharge channel connecting the second discharge port and the first flow channel, Furthermore, While the pressure plate is displaced in a direction that reduces the volume of the first pressure adjusting means, A liquid discharge head characterized in that the distance between the first discharge port and the pressure plate in the direction of displacement of the pressure plate is longer than the distance between the second discharge port and the pressure plate in the direction of displacement of the pressure plate.

24. A nozzle for dispensing liquid, A discharge element for generating pressure to discharge liquid from the discharge port, The discharge element is provided in a pressure chamber that communicates with the discharge port, A liquid dispensing device that can be equipped with a liquid dispensing head that can change the volume according to the liquid pressure and has a first pressure adjustment means for adjusting the liquid pressure, A first flow path connecting the first pressure regulating means and the pressure chamber, A first discharge port is provided at the upper part of the first pressure adjustment means in the vertical direction, A first discharge channel connecting the first discharge port and the first flow path, The second outlet provided in the first pressure adjustment means, A second discharge channel connecting the second discharge port and the first flow channel, Furthermore, When the volume of the first pressure regulating means decreases, A liquid discharge device characterized by comprising a flow resistance increasing means for increasing the flow resistance in a flow path through which liquid flows from the first pressure adjusting means to the first discharge port and the second discharge flow path, with respect to the flow resistance in a flow path through which liquid flows from the first pressure adjusting means to the first discharge port and the first discharge flow path, into the first flow path.

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