Liquid discharge head and liquid discharge apparatus

Abstract

An object of the present disclosure is to provide a liquid ejecting head and a liquid ejecting apparatus which can prevent deterioration of ink circulation efficiency near a nozzle and apparatus upsizing. To this end, a common supply passage and a common collection passage are provided as independent passages. Ink supplied from the common supply passage is supplied to a pressure chamber through a supply connection passage, and is collected from the pressure chamber into the common collection passage through a collection connection passage. In addition, the ink is caused to flow through the pressure chamber along a main scanning direction.

Description

TECHNICAL FIELD

[0001] The present application relates to a liquid ejecting apparatus including a liquid ejecting head. BACKGROUND

[0002] Japanese Patent Application Publication No. 2011-098491 discloses a liquid ejecting apparatus including a circulation passage that is responsible for supplying and collecting ink and through which ink circulates, and ejecting ink from an inkjet head.

[0003] In the configuration of Japanese Patent Application Publication No. 2011-098491, ink circulates through the circulation passage that is responsible for supplying and collecting ink, but does not circulate at the nozzle portion that ejects ink. This results in the possibility of generating air bubbles and thickening ink within the nozzle portion. As a result, image quality can deteriorate due to defective ejection.

[0004] Further, in a configuration in which a circulation passage is provided along the nozzle arrangement direction and ink circulates along the nozzle arrangement direction, as in Japanese Patent Application Publication No. 2011-098491, the circulation passage needs to be provided longer than the length of the nozzle row. This increases the size of the inkjet head in the direction along the nozzle row, which results in the possibility of the apparatus becoming large-sized. SUMMARY

[0005] Therefore, the present application provides a liquid ejecting head and a liquid ejecting apparatus that can prevent deterioration of the circulation efficiency of ink in the vicinity of a nozzle and the apparatus from becoming large-sized.

[0006] The liquid ejecting head of the present application ejects liquid during movement in a main scanning direction, the liquid ejecting head including: an ejection module having a plurality of nozzle openings through which the liquid can be ejected using operation of an energy generating element; and a circulation unit configured to circulate the liquid by supplying the liquid to the ejection module and collecting the liquid from the ejection module. Here, the ejection module has: a pressure chamber that communicates with the nozzle openings; a supply passage through which the liquid is supplied to the pressure chamber; and a collection passage that is provided separately from the supply passage and through which the liquid is collected from the pressure chamber. The liquid flows through the pressure chamber along the main scanning direction.

[0007] According to the present application, it is possible to provide a liquid ejecting head and a liquid ejecting apparatus that can prevent deterioration of the circulation efficiency of ink in the vicinity of a nozzle and the apparatus from becoming large-sized.

[0008] Other features of the present application will become apparent from the following description of exemplary embodiments with reference to the drawings. BRIEF DESCRIPTION OF DRAWINGS

[0009] FIG. 1A and FIG. 1Bare a perspective view and a block diagram showing a liquid ejection apparatus, respectively;

[0010] FIG. 2 is an obliquely upper exploded perspective view of a liquid ejection head;

[0011] FIG. 3A and FIG. 3B are a vertical cross-sectional view of the liquid ejection head and an enlarged cross-sectional view of an ejection module, respectively;

[0012] FIG. 4 is a schematic appearance view of a circulation unit;

[0013] FIG. 5 is a vertical cross-sectional view showing a circulation path;

[0014] FIG. 6 is a block diagram schematically showing a circulation path;

[0015] FIG. 7A to FIG. 7C is a cross-sectional view showing an example of a pressure adjustment unit;

[0016] FIG. 8A and FIG. 8B is an appearance perspective view of a circulation pump;

[0017] FIG. 9 is FIG. 8A is a cross-sectional view of the circulation pump shown along the line IX-IX;

[0018] FIG. 10A to FIG. 10E is a view explaining the flow of ink inside the liquid ejection head;

[0019] FIG. 11A and FIG. 11B is a schematic view showing a circulation path in an ejection unit;

[0020] FIG. 12 is a view showing an opening plate;

[0021] FIG. 13 is a view showing an ejection element substrate;

[0022] FIG. 14A to FIG. 14C is a cross-sectional view showing the flow of ink in an ejection unit;

[0023] FIG. 15A and FIG. 15B is a cross-sectional view showing the vicinity of an ejection port;

[0024] FIG. 16A and FIG. 16B is a cross-sectional view showing the vicinity of an ejection port of a comparative example;

[0025] FIG. 17 is a view showing a comparative example of an ejection element substrate;

[0026] FIG. 18A and FIG. 18B is a view showing a channel configuration of a liquid ejection head;

[0027] FIG. 19 is a view showing a connection state between a main unit of a liquid ejection apparatus and a liquid ejection head;

[0028] FIG. 20A is a view showing a channel configuration of a liquid ejection head in a modification;

[0029] FIG. 20B is a view showing a channel configuration of a liquid ejection head in a modification; and

[0030] FIG. 21 is a view showing a liquid ejection head in another embodiment. DETAILED DESCRIPTION

[0031] A preferred embodiment of the present disclosure will be specifically described with reference to the accompanying drawings. Note that the following embodiments do not limit the scope of the present disclosure, and not all combinations of features described in the embodiments are essential to the means of solving the problems of the present disclosure. Note that the same components are denoted by the same reference numerals. The present embodiment will be described using a thermal-type ejection element in which a liquid is ejected by generating a bubble by using an electrothermal conversion element as an example of each ejection element that ejects a liquid, but the present embodiment is not limited to this example. The present embodiment is also applicable to a liquid ejection head in which a piezoelectric element is used to eject a liquid and a liquid ejection head in which another ejection method is used. In addition, a pump, a pressure regulating unit, and the like to be described below are not limited to the configurations described in the embodiments and shown in the drawings. In the following description, the basic configuration of the present disclosure will be first discussed, and then features of the present disclosure will be described.

[0032] <LIQUID EJECTION APPARATUS>

[0033] FIG. 1A is a view for explaining a liquid ejection apparatus, and is an enlarged view of a liquid ejection head of the liquid ejection apparatus and its vicinity. First, the schematic configuration of the liquid ejection apparatus 50 in the present embodiment will be described with reference to FIG. 1A and FIG. 1B FIG. 1A is a perspective view schematically showing a liquid ejection apparatus using the liquid ejection head 1. The liquid ejection apparatus 50 in the present embodiment is configured as a serial inkjet printer apparatus that performs printing on a print medium P by ejecting ink as a liquid in a process of scanning the liquid ejection head 1.

[0034] ​The liquid discharge head 1 is mounted on the carriage 60. The carriage 60 is reciprocated in the main scanning direction (X direction) along the guide shaft 51. The print medium P is conveyed in the sub scanning direction (Y direction) intersecting the main scanning direction (in this example, perpendicularly intersecting) by the conveyance rollers 55, 56, 57, and 58. Note that in the drawings to be referred to below, the Z direction represents the up-down direction and intersects (in this example, perpendicularly intersects) the X-Y plane defined by the X direction and the Y direction. The liquid discharge head 1 is configured to be detachable from and attachable to the carriage 60 by a user.

[0035] The liquid discharge head 1 includes a circulation unit 54 and a discharge unit 3 (see FIG. 2 ) to be described later. Although a specific configuration will be described later, the discharge unit 3 includes a plurality of discharge ports and an energy-generating element (hereinafter referred to as a "discharge element") that generates discharge energy for discharging liquid from each of the discharge ports.

[0036] The liquid discharge apparatus 50 further includes an ink cartridge 2 that serves as an ink supply source and an external pump 21. The ink stored in the ink cartridge 2 is supplied to the circulation unit 54 through the ink supply tube 59 by the driving force of the external pump 21.

[0037] The liquid discharge apparatus 50 forms a predetermined image on the print medium P by repeating a printing scan involving performing printing by causing the liquid discharge head 1 mounted on the carriage 60 to discharge ink in the course of moving in the main scanning direction and a conveyance operation involving conveying the print medium P in the sub scanning direction. Note that the liquid discharge head 1 in the present embodiment is capable of discharging four types of ink, namely, black (B), cyan (C), magenta (M), and yellow (Y) ink, and prints a full-color image using these inks. Here, the ink that can be discharged from the liquid discharge head 1 is not limited to the above four types of ink. The present disclosure is also applicable to a liquid discharge head that discharges other types of ink. In short, the type and number of inks to be discharged from the liquid discharge head are not limited.

[0038] In addition, in the liquid discharge apparatus 50, a cap member (not shown) that covers the discharge port face of the liquid discharge head 1 on which the discharge ports are formed is provided at a position separated from the conveyance path of the print medium P in the X direction. The cap member covers the discharge port face of the liquid discharge head 1 during a non-printing operation and serves to prevent the discharge ports from drying, protect the discharge ports, perform an operation of sucking ink from the discharge ports, and the like.

[0039] Note that, FIG. 1AThe liquid ejection head 1 shown in FIG. 1 represents an example in which four circulation units 54 corresponding to four types of ink are included in the liquid ejection head 1, but it is enough that the circulation units 54 included correspond to the type of liquid to be ejected. In addition, a plurality of circulation units 54 for the same type of liquid can be included. In summary, the liquid ejection head 1 can have a configuration including one or more circulation units. The liquid ejection head 1 can be configured to circulate not all four types of ink, but only at least one type of ink.

[0040] FIG. 1B is a block diagram showing a control system of the liquid ejection apparatus 50. The CPU 103 functions as a control unit that controls the operation of each unit of the liquid ejection apparatus 50 based on a program such as a processing program stored in the ROM 101. The RAM 102 functions as a work area or the like in which the CPU 103 executes processing. The CPU 103 receives image data from the host apparatus 400 outside the liquid ejection apparatus 50, and controls the head driver 1A to control the driving of the ejection elements provided in the ejection unit 3. The CPU 103 also controls the drivers used by various actuators provided in the liquid ejection apparatus. For example, the CPU 103 controls a motor driver 105A used by a carriage motor 105 for moving the carriage 60, a motor driver 104A used by a conveyance motor 104 for conveying the print medium P, and the like. In addition, the CPU 103 controls a pump driver 500A used by the circulation pump 500 described later, a pump driver 21A used by the external pump 21, and the like. Note that, FIG. 1B A configuration in which image data is received from the host apparatus 400 and processing is executed is shown, but the liquid ejection apparatus 50 can execute processing regardless of whether data is given from the host apparatus 400.

[0041] <Basic configuration of liquid ejection head>

[0042] FIG. 2 is a diagonally upper-front exploded perspective view of the liquid ejection head 1 in the present embodiment. FIG. 3A and FIG. 3B is FIG. 2 is a cross-sectional view of the liquid ejection head 1 shown in FIG. 1 along the IIIA- IIIA line. FIG. 3A is a vertical cross-sectional view of the entire liquid ejection head 1, FIG. 3B is FIG. 3A is an enlarged view of the ejection module shown in FIG. 1. The basic configuration of the liquid ejection head 1 in the present embodiment will be mainly described below with reference to FIG. 2 to FIG. 3B and FIG. 1A

[0043] As FIG. 2 ​As shown, the liquid ejector head 1 includes a circulation unit 54 and an ejection unit 3 for ejecting ink supplied from the circulation unit 54 onto the printing medium P. In this embodiment, the liquid ejector head 1 is fixedly supported on the carriage 60 of the liquid ejection device 50 by a positioning unit and electrical contacts (not shown) provided to the carriage 60. The liquid ejector head 1 moves along the carriage 60... FIG. 1A As shown, ink is ejected onto the printing medium P during the movement in the main scanning direction (X direction) to perform printing.

[0044] The external pump 21 connected to the ink cartridge 2, which serves as the ink supply source, includes an ink supply tube 59 (see [link]). FIG. 1A Each of these ink supply tubes 59 has a liquid connector (not shown) at its front end. With the liquid nozzle 1 installed in the liquid ejection device 50, the liquid connector, located at the front end of the ink supply tube 59 and serving as the inlet through which the liquid is introduced, is hermetically connected to a liquid connector insertion port 53a on the head housing 53 of the liquid nozzle 1. As a result, an ink supply path is formed extending from the ink cartridge 2 to the liquid nozzle 1 via the external pump 21. In this embodiment, four types of ink are used. Therefore, four groups, each including the ink cartridge 2, the external pump 21, the ink supply tube 59, and the circulation unit 54, are provided for each type of ink, and four ink supply paths corresponding to each type of ink are formed independently. As described above, the liquid ejection device 50 in this embodiment includes an ink supply system to which ink is supplied from the ink cartridge 2 located outside the liquid nozzle 1. Note that the liquid ejection device 50 in this embodiment does not include an ink collection system for collecting ink from the liquid nozzle 1 into the ink cartridge 2. Therefore, the liquid ejector head 1 includes a liquid connector insertion port 53a for connection to the ink supply tube 59 of the ink cartridge 2, but does not include a connector insertion port for connection to the tube used to collect ink from the liquid ejector head 1 into the ink cartridge 2. Note that a liquid connector insertion port 53a is provided for each type of ink.

[0045] exist FIG. 3A In the accompanying drawings, reference numerals 54B, 54C, 54M, and 54Y denote the looping units used for black, cyan, magenta, and yellow inks, respectively. These looping units have substantially the same construction, and unless otherwise specified, each looping unit will be referred to as "looping unit 54" in this embodiment.

[0046] exist FIG. 2 and FIG. 3A In the process, the ejection unit 3 includes two ejection modules 300, a first support member 4, a second support member 7, an electrical wiring member (electrical wiring strip) 5, and an electrical contact substrate 6. For example... FIG. 3BAs shown, each ejection module 300 includes a silicon substrate 310 with a thickness of 0.5 mm to 1 mm and a plurality of ejection elements 15 disposed on one surface of the silicon substrate 310. In this embodiment, each ejection element 15 includes an electrothermal conversion element (heater) that generates heat energy as ejection energy for ejecting liquid. Power is supplied to each ejection element 15 via electrical wiring formed on the silicon substrate 310 by a film deposition technique.

[0047] Additionally, on the surface of the silicon substrate 310 ( FIG. 3B An ejection port forming member 320 is formed on the lower surface of the substrate 310. In the ejection port forming member 320, multiple pressure chambers 12 corresponding to multiple ejection elements 15 and multiple ejection ports 13 for ejecting ink are formed using photolithography. Additionally, a common supply channel 18 and a common collection channel 19 are formed in the silicon substrate 310. Furthermore, a supply connection channel 323 and a collection connection channel 324 are formed in the silicon substrate 310. The common supply channel 18 and the pressure chambers 12 are connected to each other through the supply connection channel 323, and the common collection channel 19 and the pressure chambers 12 are connected to each other through the collection connection channel 324. In this embodiment, an ejection module 300 is configured to eject two types of ink. Specifically, in... FIG. 3A Of the two ejection modules shown, the one located in FIG. 3A The ejection module 300 on the left side of the middle ejects black and cyan ink. FIG. 3A The ejector module 300 on the right ejects magenta and yellow ink. Note that this combination is merely an example, and any combination of inks can be used. This configuration allows one ejector module to eject one type of ink or three or more types of ink. The two ejector modules 300 do not need to eject the same amount of ink of the same type. This configuration can include only one ejector module 300, or three or more ejector modules 300. Additionally, in FIG. 3A and FIG. 3B In the example shown, for an ink of one color, two rows of nozzles extending along the Y direction are formed. For each of the plurality of nozzles 13 forming each nozzle row, a pressure chamber 12, a common supply channel 18, and a common collection channel 19 are formed. Note that a feature of this disclosure is the flow direction of the liquid flowing through the pressure chamber 12. This will be explained in detail later.

[0048] The ink supply port and ink collection port, as described later, are formed on the back side of the silicon substrate 310. FIG. 3B (On the upper surface of the middle). Through the ink supply port, ink is supplied from the ink supply channel 48 into multiple common supply channels 18. Through the ink collection port, ink is collected from multiple common collection channels 19 into the ink collection channel 49.

[0049] Note that the ink supply port and ink collection port correspond to the openings used for supplying and collecting ink during the forward ink cycle, as described later. Specifically, during the forward ink cycle, ink is supplied from the ink supply port into the common supply channel 18, and ink is collected from the common collection channel 19 into the ink collection port. Note that an ink cycle in which ink flows in the opposite direction can also be performed. In this case, ink is supplied from the aforementioned ink collection port into the common collection channel 19, and ink is collected from the common supply channel 18 into the ink supply port.

[0050] like FIG. 3A As shown, the back of the ejection module 300 ( FIG. 3A The upper surface of the middle part is bonded and fixed to one surface of the first support member 4. FIG. 3A The ink supply channel 48 and the ink collection channel 49, penetrating from one surface of the first support member 4 to the opposite surface of the first support member 4, are formed in the first support member 4. An opening on one side of the ink supply channel 48 communicates with the aforementioned ink supply port in the silicon substrate 310. An opening on the same side of the ink collection channel 49 communicates with the aforementioned ink collection port in the silicon substrate 310. Note that the ink supply channel 48 and the ink collection channel 49 are provided independently for each type of ink.

[0051] Additionally, it has an opening 7a for inserting the ejection module 300 (see...). FIG. 2 The second support member 7 is bonded and fixed to one surface of the first support member 4. FIG. 3A (The lower surface of the inkjet module 300). The electrical wiring component 5, which is to be electrically connected to the inkjet module 300, is held on the second support component 7. The electrical wiring component 5 is a component for applying electrical signals for inkjet printing to the inkjet module 300. The electrical connection between the inkjet module 300 and the electrical wiring component 5 is sealed with a sealant (not shown) to prevent corrosion from ink and external impacts.

[0052] Additionally, an anisotropic conductive film (not shown) is used to bond the electrical contact substrate 6 to the end 5a of the electrical wiring component 5 via thermoforming (see [link to documentation]). FIG. 2 The electrical wiring component 5 and the electrical contact substrate 6 are electrically connected to each other. The electrical contact substrate 6 has an external signal input terminal (not shown) for receiving electrical signals from the liquid ejection device 50.

[0053] In addition, combined with component 8 ( FIG. 3A A supply port 88 and a collection port 89 are provided between the first support member 4 and the circulation unit 54. In the connecting member 8, a supply port 88 and a collection port 89 are formed for each type of ink. Through the supply port 88 and the collection port 89, the ink supply channel 48 and the ink collection channel 49 in the first support member 4 communicate with each other with the channels formed in the circulation unit 54. Incidentally, in FIG. 3AIn this case, the supply port 88B and the collection port 89B are used for black ink, the supply port 88C and the collection port 89C are used for cyan ink. In addition, the supply port 88M and the collection port 89M are used for magenta ink, and the supply port 88Y and the collection port 89Y are used for yellow ink.

[0054] Note that the openings at one end of the ink supply passage 48 and the ink collection passage 49 in the first support member 4 have small opening areas that match the ink supply ports and the ink collection ports in the silicon substrate 310. On the other hand, the openings at the other end of the ink supply passage 48 and the ink collection passage 49 in the first support member 4 have large shapes with opening areas that are the same as the opening areas formed in the coupling member 8 to match the passages in the circulation unit 54. With this configuration, an increase in the passage resistance of the ink collected from each collection passage can be suppressed. Note that the shapes of the openings at one end and the other end of the ink supply passage 48 and the ink collection passage 49 are not limited to the above examples.

[0055] In the liquid ejecting head 1 having the above configuration, the ink supplied to the circulation unit 54 passes through the supply ports 88 in the coupling member 8 and the ink supply passages 48 in the first support member 4, and flows from the ink supply ports in the ejecting module 300 into the common supply passage 18. Thereafter, the ink flows from the common supply passage 18 through the supply connection passage 323 into the pressure chamber 12. When the ejecting element 15 is driven, a part of the ink flowing into the pressure chamber is ejected from the ejection port 13. The remaining ink that is not ejected flows from the pressure chamber 12 through the collection connection passage 324 and the common collection passage 19, and from the ink collection ports into the ink collection passages 49 in the first support member 4. Then, the ink flowing into the ink collection passages 49 flows through the collection ports 89 in the coupling member 8 into the circulation unit 54 and is collected.

[0056] <Configuration elements of circulation unit>

[0057] FIG. 4 is a schematic appearance view of one circulation unit 54 for one type of ink used in the printing device of this embodiment. A filter 110, a first pressure regulating unit 120, a second pressure regulating unit 150, and a circulation pump 500 are arranged in the circulation unit 54. As FIG. 5 and FIG. 6 indicated, these configuration elements are connected by passages to form a circulation path for supplying and collecting ink to and from the ejecting module 300 in the liquid ejecting head 1.

[0058] <Circulation path in liquid ejecting head>

[0059] FIG. 5 is a schematic view showing an up-down direction cross-sectional view of a circulation path for one type of ink (one color of ink) formed in the liquid ejecting head 1. FIG. 5The relative positions of the components (such as the first pressure regulating unit 120, the second pressure regulating unit 150, and the circulation pump 500) are simplified to more clearly illustrate the circulation path. Therefore, the relative positions of the components differ from those mentioned later. FIG. 19 The relative positions of the components. Incidentally, FIG. 6 It is shown schematically. FIG. 5 The diagram shows a loop path. FIG. 5 and FIG. 6 As shown, the first pressure regulating unit 120 includes a first valve chamber 121 and a first pressure control chamber 122. The second pressure regulating unit 150 includes a second valve chamber 151 and a second pressure control chamber 152. The first pressure regulating unit 120 is configured such that the controlled pressure therein is higher than the controlled pressure in the second pressure regulating unit 150. In this embodiment, the two pressure regulating units 120 and 150 are used to circulate within a certain pressure range within the circulation path. Furthermore, this configuration causes ink to flow through the pressure chamber 12 (ejection element 15) at a flow rate corresponding to the pressure difference between the first pressure regulating unit 120 and the second pressure regulating unit 150. Reference will be made below. FIG. 5 and FIG. 6 This describes the circulation path in liquid ejector head 1 and the flow of ink within that path. Note that... FIG. 5 and FIG. 6 The arrows in the diagram indicate the direction of ink flow.

[0060] First, the connection of the components in the liquid ejector head 1 will be explained. The ink cartridge 2, which is located outside the liquid ejector head 1... FIG. 6 The ink stored in the liquid nozzle 1 is sent to the external pump 21 via the ink supply pipe 59. FIG. 1A The filter 110 is connected to the circulation unit 54. The filter 110 is arranged in the ink channel upstream of the circulation unit 54. The ink supply path downstream of the filter 110 is connected to the first valve chamber 121 of the first pressure regulating unit 120. The first valve chamber 121 is connected to the first pressure control chamber 122 via a connection port 191A, which can be accessed by... FIG. 5 The valve 190A shown is open and closed.

[0061] The first pressure control chamber 122 is connected to the supply channel 130, bypass channel 160, and pump outlet channel 180 of the circulating pump 500. The supply channel 130 is connected to the common supply channel 18 via the ink supply port provided in the ejection module 300. Additionally, the bypass channel 160 is connected to the second valve chamber 151 provided in the second pressure regulating unit 150. The second valve chamber 151 is connected to the second pressure control chamber 152 via a communication port 191B. FIG. 5 The valve 190B shown is open and closed. Note that... FIG. 5 andFIG. 6 An example is shown in which one end of the bypass passage 160 is connected to the first pressure control chamber 122 of the first pressure regulating unit 120, and the other end of the bypass passage 160 is connected to the second valve chamber 151 of the second pressure regulating unit 150. However, one end of the bypass passage 160 can be connected to the supply passage 130, and the other end of the bypass passage can be connected to the second valve chamber 151.

[0062] The second pressure control chamber 152 is connected to the collection passage 140. The collection passage 140 is connected to the common collection passage 19 through the above-described ink collection port provided in the ejection module 300. In addition, the second pressure control chamber 152 is connected to the circulation pump 500 through the pump inlet passage 170. Note that, FIG. 5 Reference numeral 170a in FIG. 17 indicates an inlet of the pump inlet passage 170. Next, the flow of ink in the liquid ejection head 1 having the above configuration will be described. As shown in FIG. 18, FIG. 6 The ink stored in the ink cartridge 2 is pressurized by the external pump 21 provided in the liquid ejection apparatus 50, becomes an ink flow under positive pressure, and is supplied to the circulation unit 54 of the liquid ejection head 1, as shown in FIG. 19.

[0063] The ink supplied to the circulation unit 54 passes through the filter 110, whereby foreign matter such as dust and air bubbles are removed. Then, the ink flows into the first valve chamber 121 provided in the first pressure regulating unit 120. In the case where the ink passes through the filter 110, the pressure of the ink is reduced due to pressure loss, but the pressure of the ink at this time is still positive. Thereafter, in the case where the valve 190A is open, the ink flowing into the first valve chamber 121 passes through the communication port 191A and flows into the first pressure control chamber 122. In the case where the ink passes through the communication port 191A, the pressure of the ink flowing into the first pressure control chamber 122 is switched from positive pressure to negative pressure due to pressure loss.

[0064] Next, the flow of ink in the circulation path will be described. The circulation pump 500 is operated in such a manner that the ink sucked from the pump inlet passage 170 located upstream of the circulation pump 500 is sent to the pump outlet passage 180 located downstream of the circulation pump 500. Therefore, when the pump is driven, the ink supplied to the first pressure control chamber 122 flows into the supply passage 130 and the bypass passage 160 together with the ink sent out from the pump outlet passage 180. In the present embodiment, although details will be described later, a piezoelectric diaphragm pump using a piezoelectric element mounted to a diaphragm as a drive source is used as the circulation pump capable of sending out liquid. The piezoelectric diaphragm pump is a pump that sends out liquid by inputting a drive voltage to a piezoelectric element to change the volume of a pump chamber and alternately moving two check valves in response to a change in pressure.

[0065] The ink flowing into the supply passage 130 flows into the pressure chamber 12 from the ink supply port in the ejection module 300 through the common supply passage 18. When the ejection element 15 is driven (heated), a part of the ink is ejected from the ejection port 13. In addition, the remaining ink not used in the ejection flows through the pressure chamber 12 and through the common collection passage 19. Thereafter, the ink flows into the collection passage 140 connected to the ejection module 300. The ink flowing into the collection passage 140 flows into the second pressure control chamber 152 of the second pressure regulating unit 150.

[0066] On the other hand, the ink flowing into the bypass passage 160 from the first pressure control chamber 122 flows into the second valve chamber 151, passes through the communication port 191B, and then flows into the second pressure control chamber 152. When the circulation pump 500 is driven, the ink flowing into the second pressure control chamber 152 through the bypass passage 160 and the ink collected from the collection passage 140 are sucked into the circulation pump 500 through the pump inlet passage 170. Then, the ink sucked into the circulation pump 500 is sent to the pump outlet passage 180 and flows into the first pressure control chamber 122 again. Thereafter, the ink flowing into the second pressure control chamber 152 from the first pressure control chamber 122 through the supply passage 130 and the ejection module 300 and the ink flowing into the second pressure control chamber 152 through the bypass passage 160 flow into the circulation pump 500. Then, the ink is sent from the circulation pump 500 to the first pressure control chamber 122. In this way, the circulation of the ink is performed within the circulation path.

[0067] As described above, in the present embodiment, the liquid is circulated through the respective circulation paths formed in the liquid ejection head 1 by the circulation pump 500. This makes it possible to suppress thickening of the ink in the ejection module 300 and deposition of the precipitated components of the color material ink. Therefore, it is possible to maintain excellent fluidity of the ink in the ejection module 300 and excellent ejection characteristics at the ejection port.

[0068] In addition, the circulation path in the present embodiment is configured to be completed within the liquid ejection head 1. Therefore, the length of the circulation path is significantly shorter compared to the case where the ink is circulated between the ink cartridge 2 arranged outside the liquid ejection head 1 and the liquid ejection head 1. Therefore, it is possible to circulate the ink with a small circulation pump.

[0069] Furthermore, this configuration ensures that the channel connecting the liquid ejector head 1 and the ink cartridge 2 includes only a channel for supplying ink. In other words, a configuration that eliminates the need for a channel to collect ink from the liquid ejector head 1 into the ink cartridge 2 is adopted. Therefore, only an ink supply tube connecting the ink cartridge 2 and the liquid ejector head 1 is required, and an ink collection tube is unnecessary. Consequently, the internal structure of the liquid ejector device 50 is simpler, with fewer tubes. This allows for miniaturization of the entire device. In addition, the reduction in the number of tubes reduces ink pressure fluctuations caused by tube oscillation during the main scan of the liquid ejector head 1. Furthermore, the oscillation of the tubes during the main scan of the liquid ejector head 1 increases the drive load on the carriage motor that drives the carriage 60. Therefore, the reduction in the number of tubes lowers the drive load on the carriage motor, which simplifies the main scan mechanism, including the carriage motor, etc. In addition, since it is not necessary to collect ink from the liquid ejector head 1 into the ink cartridge, the external pump 21 can also be miniaturized. As described above, according to this embodiment, the liquid ejector device 50 can be miniaturized and its cost reduced.

[0070] <Pressure Regulation Unit>

[0071] FIG. 7A to FIG. 7C This is a diagram showing an example of a pressure regulating unit. (Refer to...) FIG. 7A to FIG. 7C The structure and operation of the pressure regulating units (first pressure regulating unit 120 and second pressure regulating unit 150) incorporated in the liquid ejector head 1 will be described in more detail. Note that the first pressure regulating unit 120 and the second pressure regulating unit 150 have substantially the same structure. Therefore, the following description will take the first pressure regulating unit 120 as an example. For the second pressure regulating unit 150, in FIG. 7A to FIG. 7C Only the reference numerals for the parts corresponding to those of the first pressure regulating unit are shown in the accompanying drawings. In the case of the second pressure regulating unit 150, the first valve chamber 121 and the first pressure control chamber 122 described below should be interpreted as the second valve chamber 151 and the second pressure control chamber 152, respectively.

[0072] The first pressure regulating unit 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 123 provided inside 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 123. A valve 190 is provided in the first valve chamber 121, which switches between allowing the first valve chamber 121 to communicate with the first pressure control chamber 122 through the communication port 191 and blocking the communication. The valve 190 is held at a position opposite to the communication port 191 by a valve spring 200, and has a configuration that is in close contact with the partition 123 by the urging force from the valve spring 200. The valve 190 blocks the ink from flowing through the communication port 191 by being in close contact with the partition 123. Note that the portion of the valve 190 that contacts the partition 123 is preferably formed of an elastic member so as to enhance the tightness of the contact with the partition 123. In addition, a valve shaft 190a to be inserted through the communication port 191 is provided in a protruding manner in the central portion of the valve 190. The valve 190 is separated from the partition 123 by pressurizing the valve shaft 190a against the urging force from the valve spring 200, thereby allowing the ink to flow through the communication port 191. Hereinafter, the state in which the valve 190 blocks the ink from flowing through the communication port 191 will be referred to as a "closed state", and the state in which the ink is able to flow through the communication port 191 will be referred to as an "open state".

[0073] The opening portion of the cylindrical housing 125 is closed by a flexible member 230 and a pressure plate 210. These flexible member 230 and pressure plate 210, the peripheral wall of the housing 125, and the partition 123 form the first pressure control chamber 122. The pressure plate 210 is configured to be displaceable with the displacement of the flexible member 230. Although the materials of the pressure plate 210 and the flexible member 230 are not particularly limited, for example, the pressure plate 210 can be made as a molded resin member, and the flexible member 230 can be made of a resin film. In this case, the pressure plate 210 can be fixed to the flexible member 230 by heat fusion.

[0074] A pressure regulating spring 220 (urging member) is provided between the pressure plate 210 and the partition 123. As FIG. 7AAs shown, the pressure plate 210 and the flexible member 230 are pressed in the direction in which the internal volume of the first pressure control chamber 122 increases by the pressing force from the pressure regulating spring 220. In addition, as the pressure in the first pressure control chamber 122 decreases, the pressure plate 210 and the flexible member 230 are displaced in the direction in which the internal volume of the first pressure control chamber 122 decreases against the pressure from the pressure regulating spring 220. Then, in the case where the internal volume of the first pressure control chamber 122 decreases to a certain volume, the pressure plate 210 abuts against the valve shaft 190a of the valve 190. Then, as the internal volume of the first pressure control chamber 122 further decreases, the valve 190 moves together with the valve shaft 190a against the pressing force from the valve spring 200, thereby separating from the partition 123. As a result, the communication port 191 switches to the open state FIG. 7B .

[0075] In the present embodiment, the connection in the circulation path is set such that the pressure in the first valve chamber 121 is higher than the pressure in the first pressure control chamber 122 in the case where the communication port 191 switches to the open state. In this way, in the case where the communication port 191 switches to the open state, ink flows from the first valve chamber 121 into the first pressure control chamber 122. The inflow of ink displaces the flexible member 230 and the pressure plate 210 in the direction in which the internal volume of the first pressure control chamber 122 increases. As a result, the pressure plate 210 separates from the valve shaft 190a of the valve 190, and the valve 190 is brought into close contact with the partition 123 by the pressing force from the valve spring 200, so that the communication port 191 switches to the closed state FIG. 7C .

[0076] As described above, in the first pressure regulating unit 120 of the present embodiment, in the case where the pressure in the first pressure control chamber 122 decreases below a certain pressure (for example, in the case where negative pressure becomes strong), ink flows from the first valve chamber 121 through the communication port 191. This configuration limits the pressure in the first pressure control chamber 122 from further decreasing. Therefore, the pressure in the first pressure control chamber 122 is controlled to be kept within a certain range.

[0077] Next, the pressure in the first pressure control chamber 122 will be described in more detail. Consider the state where the flexible member 230 and the pressure plate 210 are displaced in accordance with the pressure in the first pressure control chamber 122 as described above, so that the pressure plate 210 abuts against the valve shaft 190a and the communication port 191 enters the open state FIG. 7B .

[0078] P2 x S2 + F2 + (P1 - P2) x S1 + F1 = 0... Equation 1

[0079] In addition, Equation 1 is summarized as follows for P2.

[0080] P2 = -(F1 + F2 + P1 x S1) / (S2 - S1)... Equation 2

[0081] P1: pressure in the first valve chamber 121 (gauge pressure)

[0082] P2: pressure in the first pressure control chamber 122 (gauge pressure)

[0083] F1: spring force of the valve spring 200

[0084] F2: spring force of the pressure regulating spring 220

[0085] S1: pressure receiving area of the valve 190

[0086] S2: pressure receiving area of the pressure plate 210

[0087] Here, with respect to the spring force F1 of the valve spring 200 and the spring force F2 of the pressure regulating spring 220, the directions in which they push the valve 190 and the pressure plate 210 are defined as positive directions (leftward direction in FIG. 1). In addition, the configuration is such that the pressure P1 in the first valve chamber 121 and the pressure P2 in the first pressure control chamber 122 satisfy the relationship P1 > P2. FIG. 7A to FIG. 7C

[0088] When the communication port 191 is switched to the open state, the pressure P2 in the first pressure control chamber 122 is determined by Equation 2, and since the configuration is such that the relationship P1 > P2 is satisfied, ink flows from the first valve chamber 121 into the first pressure control chamber 122 when the communication port 191 is switched to the open state. As a result, the pressure P2 in the first pressure control chamber 122 no longer further decreases, and the pressure P2 is maintained at a pressure within a certain range.

[0089] On the other hand, as shown in FIG. 1, in the case where the pressure plate 210 does not abut against the valve shaft 190a and the communication port 191 is switched to the closed state, the relationship between the forces acting on the pressure plate 210 is represented by the following Equation 3. FIG. 7C

[0090] P3 x S3 + F3 = 0... Equation 3

[0091] Here, with respect to P3, Equation 3 is summarized as follows.

[0092] P3 = -F3 / S3... Equation 4

[0093] F3: spring force of the pressure regulating spring 220 in the state where the pressure plate 210 does not abut against the valve shaft 190a

[0094] ​​P3: pressure (gauge pressure) in the first pressure control chamber 122 in a state where the pressure plate 210 is not abutted on the valve shaft 190a

[0095] S3: pressure receiving area of the pressure plate 210 in a state where the pressure plate 210 is not abutted on the valve shaft 190a

[0096] Here, FIG. 7C shows a state where the pressure plate 210 and the flexible member 230 are displaced in the leftward direction in the FIG. 7C until they can be displaced to the limit. The pressure P3 in the first pressure control chamber 122, the spring force F3 of the pressure regulating spring 220, and the pressure receiving area S3 of the pressure plate 210 vary depending on the displacement amount of the pressure plate 210 and the flexible member 230 in the state of being displaced to FIG. 7C . Specifically, in the case where the pressure plate 210 and the flexible member 230 are located on the right side in the FIG. 7C with respect to themselves in the FIG. 7C , the pressure receiving area S3 of the pressure plate 210 is small, and the spring force F3 of the pressure regulating spring 220 is large. Therefore, according to the relationship in Equation 4, the pressure P3 in the first pressure control chamber 122 is small. Therefore, according to Equations 2 and 4, in the process of switching from the state of FIG. 7B to the state of FIG. 7C , the pressure in the first pressure control chamber 122 gradually increases (i.e., the negative pressure weakens toward a value close to the positive pressure side). Specifically, in the process of gradually displacing the pressure plate 210 and the flexible member 230 in the leftward direction from the state where the communication port 191 is in the open state to the state where the internal volume of the first pressure control chamber reaches the limit of the displacement of the pressure plate 210 and the flexible member 230, the pressure in the first pressure control chamber 122 gradually increases. In other words, the negative pressure weakens.

[0097] <recirculation pump>

[0098] Next, the configuration and operation of each recirculation pump 500 incorporated in the above liquid ejecting head 1 will be described in detail with reference to FIG. 8A and FIG. 8B , and FIG. 9

[0099] FIG. 8A and FIG. 8B are appearance perspective views of the recirculation pump 500. FIG. 8A is an appearance perspective view showing the front side of the recirculation pump 500, FIG. 8B ​is an appearance perspective view showing the back surface side of the circulation pump 500. The housing of the circulation pump 500 includes a pump housing 505 and a cover 507 fixed to the pump housing 505. The pump housing 505 includes a housing portion main body 505a and a passage connection member 505b adhesively fixed to the outer surface of the housing portion main body 505a. In each of the housing portion main body 505a and the passage connection member 505b, a pair of through holes communicating with each other are formed at two different positions. One of the pair of through holes provided at one position forms a pump supply hole 501. The other of 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 passage 170 connected to the second pressure control chamber 152. The ink supplied from the pump supply hole 501 passes through a pump chamber 503 (see FIG. 9 ) explained later and is discharged from the pump discharge hole 502.

[0100] FIG. 9 is a sectional view of the circulation pump 500 shown in FIG. 8A along the IX-IX line. A diaphragm 506 is bonded to the inner surface of the pump housing 505, and a pump chamber 503 is formed between the diaphragm 506 and a recess formed in the inner surface of the pump housing 505. The pump chamber 503 communicates with the pump supply hole 501 and the pump discharge hole 502 formed in the pump housing 505. In addition, a check valve 504a is provided in the middle portion of the pump supply hole 501. A check valve 504b is provided in the middle portion of the pump discharge hole 502. Specifically, the check valve 504a is arranged so that a part thereof can move in the leftward direction in a space 512a formed at the middle portion of the pump supply hole 501. The check valve 504b is arranged so that a part thereof can move in the rightward direction in a space 512b formed at the middle portion of the pump discharge hole 502. FIG. 9 . FIG. 9 .

[0101] When the diaphragm 506 is displaced in a manner to increase the volume of the pump chamber 503, the pump chamber 503 is depressurized. In response to this displacement, the check valve 504a is separated from the opening of the pump supply hole 501 in the space 512a (i.e., moves in the leftward direction in FIG. 9 .

[0102] On the other hand, when the pump chamber 503 is depressurized, the check valve 504b comes into close contact with the wall surface around the opening in the pump housing 505, thereby switching to a closed state in which the check valve 504b blocks the flow of ink through the pump discharge hole 502. In addition, when the pump chamber 503 is pressurized, the check valve 504b is separated from the opening in the pump housing 505 and moves toward the space 512b (i.e., moves in the right direction in FIG. 12), thereby allowing the flow of ink through the pump discharge hole 502. FIG. 9

[0103] Note that the material of each of the check valves 504a and 504b only needs to be a material that can be deformed according to the pressure in the pump chamber 503. For example, the material of each of the check valves 504a and 504b can be made of an elastic material such as ethylene propylene diene rubber (EPDM) or an elastomer, or a film or sheet of polypropylene, or the like. However, the material is not limited to these.

[0104] As described above, the pump chamber 503 is formed by combining the pump housing 505 and the diaphragm 506. Therefore, the pressure in the pump chamber 503 changes as the diaphragm 506 deforms. For example, in a case where the diaphragm 506 is displaced toward the pump housing 505 (displaced toward the right in FIG. 12) so as to decrease the volume of the pump chamber 503, the pressure in the pump chamber 503 increases. As a result, the check valve 504b arranged so as to face the pump discharge hole 502 switches to an open state, thereby discharging ink in the pump chamber 503. At this time, the check valve 504a arranged so as to face the pump supply hole 501 comes into close contact with the wall surface around the pump supply hole 501, thereby suppressing the backflow of ink from the pump chamber 503 into the pump supply hole 501. FIG. 9

[0105] In contrast, in a case where the diaphragm 506 is displaced in a direction in which the pump chamber 503 widens, the pressure in the pump chamber 503 decreases. As a result, the check valve 504a arranged so as to face the pump supply hole 501 switches to an open state, so that ink is supplied into the pump chamber 503. At this time, the check valve 504b arranged in the pump discharge hole 502 comes into close contact with the wall surface around the opening formed in the pump housing 505 to close the opening. This suppresses the backflow of ink from the pump discharge hole 502 into the pump chamber 503.

[0106] ​​As described above, in the circulation pump 500, ink is sucked and discharged as the diaphragm 506 is deformed and thereby changes the pressure in the pump chamber 503. At this time, in a case where a bubble has entered the pump chamber 503, the displacement of the diaphragm 506 changes the pressure in the pump chamber 503 to a small extent due to expansion or contraction of the bubble. Therefore, the amount of liquid to be discharged decreases. To address this phenomenon, the pump chamber 503 is arranged in parallel with gravity so that a bubble that has entered the pump chamber 503 can easily collect in the upper portion of the pump chamber 503. Further, the pump discharge hole 502 is arranged higher than the center of the pump chamber 503. This improves the ease of bubble discharge in the pump, thereby stabilizing the flow rate.

[0107] <Flow of ink inside the liquid ejection head>

[0108] FIG. 10A to FIG. 10E is a diagram that illustrates the flow of ink inside the liquid ejection head. Reference will be made to FIG. 10A to FIG. 10E to explain the ink circulation performed inside the liquid ejection head 1. To more clearly illustrate the relative positions of the components in FIG. 10A to FIG. 10E such as the first pressure regulating unit 120, the second pressure regulating unit 150, and the circulation pump 500, the relative positions of the components are simplified in FIG. 19 . Therefore, the relative positions of the components are different from those of the components in FIG. 10A The flow of ink in a case where a printing operation is performed by performing printing by ejecting ink from the ejection ports 13 is schematically shown. Note that FIG. 10A the arrows in

[0109] During the printing operation, the circulation pump 500 is in an ON state (driven state) so that ink flowing out of the first pressure control chamber 122 flows into the supply passage 130 and the bypass passage 160. The ink that has flowed into the supply passage 130 passes through the ejection module 300 and then flows into the collection passage 140. Thereafter, the ink is supplied into the second pressure control chamber 152.

[0110] On the other hand, the ink flowing from the first pressure control chamber 122 into the bypass passage 160 flows into the second pressure control chamber 152 through the second valve chamber 151. The ink flowing into the second pressure control chamber 152 flows through the pump inlet passage 170, the circulation pump 500, and the pump outlet passage 180, and then flows into the first pressure control chamber 122 again. At this time, the controlled pressure in the first valve chamber 121 is set to be higher than the controlled pressure in the first pressure control chamber 122 based on the relationship in the above Equation 2. Therefore, the ink in the first pressure control chamber 122 does not flow into the first valve chamber 121, but is supplied to the ejection module 300 again through the supply passage 130. The ink flowing into the ejection module 300 flows through the collection passage 140, the second pressure control chamber 152, the pump inlet passage 170, the circulation pump 500, and the pump outlet passage 180, and then flows into the first pressure control chamber 122 again. The ink circulation inside the liquid ejection head 1 is performed as described above.

[0111] In the above ink circulation, the pressure difference between the controlled pressure in the first pressure control chamber 122 and the controlled pressure in the second pressure control chamber 152 determines the circulation amount (flow rate) of the ink inside the ejection module 300. In addition, the pressure difference is set to obtain a circulation amount that can suppress thickening of the ink near the ejection ports in the ejection module 300. Incidentally, the amount of ink consumed by printing is supplied to the first pressure control chamber 122 from the ink cartridge 2 through the filter 110 and the first valve chamber 121. How the consumed ink is supplied will now be described in detail. The amount of ink in the circulation path decreases by the amount of ink consumed by printing. Therefore, the pressure in the first pressure control chamber 122 decreases, resulting in a decrease in the amount of ink in the first pressure control chamber. When the amount of ink in the first pressure control chamber 122 decreases, the internal volume of the first pressure control chamber 122 decreases accordingly. As the internal volume of the first pressure control chamber 122 decreases, the communication port 191A switches to the open state, so that ink is supplied from the first valve chamber 121 to the first pressure control chamber 122. As this ink supplied from the first valve chamber 121 passes through the communication port 191A, a pressure loss occurs in the supplied ink. As the ink flows into the first pressure control chamber 122, the positive pressure received by the ink switches to a negative pressure. As the ink flows from the first valve chamber 121 into the first pressure control chamber 122, the pressure in the first pressure control chamber increases. When the internal volume of the first pressure control chamber increases, the communication port 191A switches to the closed state. As described above, the communication port 191A repeatedly switches between the open state and the closed state in accordance with ink consumption. Incidentally, in the case where no ink is consumed, the communication port 191A remains in the closed state.

[0112] FIG. 10BThe ink flow immediately after the printing operation is completed and the circulation pump 500 is switched to the OFF state (stop state) is schematically shown. At the time when the printing operation is completed and the circulation pump 500 is switched to OFF, the pressure in the first pressure control chamber 122 and the pressure in the second pressure control chamber 152 are both the controlled pressure used in the printing operation. Therefore, the ink moves as shown in FIG. 10B accordance with the pressure difference between the pressure in the first pressure control chamber 122 and the pressure in the second pressure control chamber 152. Specifically, the ink flow from the first pressure control chamber 122 through the supply passage 130 to the ejection module 300, and then through the collection passage 140 to the second pressure control chamber 152 continues. In addition, the ink flow from the first pressure control chamber 122 through the bypass passage 160 and the second valve chamber 151 to the second pressure control chamber 152 continues.

[0113] By these ink flows, the amount of ink that moves from the first pressure control chamber 122 to the second pressure control chamber 152 is supplied from the ink cartridge 2 through the filter 110 and the first valve chamber 121 to the first pressure control chamber 122. Therefore, the internal volume of the first pressure control chamber 122 is kept constant. In accordance with the relationship in Equation 2 described above, the spring force Fl of the valve spring 200, the spring force F2 of the pressure regulating spring 220, the pressure receiving area Sl of the valve 190, and the pressure receiving area S2 of the pressure plate 210 are kept constant in the case where the internal volume of the first pressure control chamber 122 is constant. Therefore, the pressure in the first pressure control chamber 122 is determined in accordance with the change in the pressure (gauge pressure) Pl in the first valve chamber 121. In this way, in the case where the pressure Pl in the first valve chamber 121 does not change, the pressure P2 in the first pressure control chamber 122 is kept at the same pressure as the controlled pressure in the printing operation.

[0114] On the other hand, the pressure in the second pressure control chamber 152 changes over time in accordance with the change in the internal volume caused by the ink flowing in from the first pressure control chamber 122. Specifically, the pressure in the second pressure control chamber 152 changes in accordance with Equation 2 until the communication port 191 is switched from the state shown in FIG. 10B to the closed state shown in FIG. 10C so that the second valve chamber 151 is not in communication with the second pressure control chamber 152. Thereafter, the pressure plate 210 is not abutted against the valve shaft 190a so that the communication port 191 is switched to the closed state. Then, as shown in FIG. 10D ink flows into the second pressure control chamber 152 from the collection passage 140. This inflow of ink displaces the pressure plate 210 and the flexible member 230. The pressure in the second pressure control chamber 152 changes in accordance with Equation 4. Specifically, the pressure increases until the internal volume of the second pressure control chamber 152 reaches the maximum.

[0115] Note that, once the internal volume of the second pressure control chamber 152 reaches the maximum, the pressure in the second pressure control chamber 152 is kept constant. In this case, the pressure in the second pressure control chamber 152 is determined in accordance with the change in the pressure (gauge pressure) P2 in the second valve chamber 151. In this way, in the case where the pressure P2 in the second valve chamber 151 does not change, the pressure in the second pressure control chamber 152 is kept at the same pressure as the controlled pressure in the printing operation. FIG. 10CIn this state, ink no longer flows from the first pressure control chamber 122 through the bypass channel 160 and the second valve chamber 151 into the second pressure control chamber 152. Therefore, ink flow through the collection channel 140 to the second pressure control chamber 152 only occurs after the ink in the first pressure control chamber 122 is supplied to the ejection module 300 via the supply channel 130. As described above, ink moves from the first pressure control chamber 122 to the second pressure control chamber 152 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 ink stops moving.

[0116] Furthermore, when 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... FIG. 10D The state shown. In the second pressure control chamber 152, as indicated. FIG. 10D In the case of the expansion shown, a reservoir capable of holding ink is formed in the second pressure control chamber 152. Note that after stopping the circulation pump 500, the process switches to... FIG. 10D The process takes approximately 1 to 2 minutes. This time can vary depending on the shape and size of the channel and the characteristics of the ink. FIG. 10D As shown, with the circulation pump 500 driven while the ink is held in the reservoir, the ink in the reservoir is supplied to the first pressure control chamber 122 via the circulation pump 500. Therefore, as FIG. 10E As shown, the ink volume in the first pressure control chamber 122 increases, causing the flexible member 230 and the pressure plate 210 to shift along the expansion direction. Then, as the circulation pump 500 continues to be driven, the state within the circulation path changes to... FIG. 10A The state shown.

[0117] Note that in the above explanation, FIG. 10A The example described is ink circulation during a printing operation. However, as mentioned above, ink can circulate even without a printing operation. Even in this case, the ink still circulates in response to the driving and stopping of the circulation pump 500. FIG. 10A to FIG. 10E The flow is shown.

[0118] Furthermore, as described above, this embodiment has used an example where the connection port 191B in the second pressure regulating unit 150 is switched to an open state when ink is circulated by driving the circulation pump 500 and switched to a closed state when ink circulation stops. However, this embodiment is not limited to this example. The controlled pressure can be set such that the connection port 191B in the second pressure regulating unit 150 remains closed even when ink is circulated by driving the circulation pump 500. This will be explained in detail below along with the function of the bypass channel 160.

[0119] The bypass passage 160 connected between the first pressure regulating unit 120 and the second pressure regulating unit 150 is provided so that, for example, in a case where the negative pressure generated inside the circulation path becomes stronger than a predetermined value, the ejection module 300 can avoid the influence of the strong negative pressure. The bypass passage 160 is also provided so that ink is supplied to the pressure chamber 12 from both the supply passage 130 and the collection passage 140.

[0120] First, an explanation will be given of an example in which the influence of the negative pressure that becomes stronger than a predetermined value on the ejection module 300 is avoided by providing the bypass passage 160. For example, changes in the ambient temperature sometimes change the properties (e.g., viscosity) of the ink. As the viscosity of the ink changes, the pressure loss inside the circulation path also changes. For example, as the viscosity of the ink decreases, the amount of pressure loss inside 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 ejection module 300 increases. Here, the ejection module 300 is maintained at a constant temperature by a temperature adjustment mechanism (not shown). Therefore, even if the ambient temperature changes, the viscosity of the ink inside the ejection module 300 remains constant. The viscosity of the ink inside the ejection module 300 remains unchanged, while the flow rate of the ink flowing through the ejection module 300 increases, so the negative pressure in the ejection module 300 becomes correspondingly stronger due to the flow resistance. If the negative pressure in the ejection module 300 becomes stronger than a predetermined value as described above, there is a possibility that the meniscus in the ejection port 13 breaks and ambient air is brought into the circulation path, which can cause a failure in performing normal ejection. In addition, even if the meniscus does not break, the negative pressure in the pressure chamber 12 can become stronger than a predetermined level and affect ejection.

[0121] For these reasons, in the present embodiment, the bypass passage 160 is formed in the circulation path. By providing the bypass passage 160, in a case where the negative pressure becomes stronger than a predetermined value, the ink flows through the bypass passage 160. Therefore, the pressure in the ejection module 300 is maintained constant. Therefore, for example, the controlled pressure in the second pressure regulating unit 150 can be set so that the communication port 191B in the second pressure regulating unit 150 remains in a closed state even if the circulation pump 500 is driven. In addition, the controlled pressure in the second pressure regulating unit 150 can be set so that the communication port 191B in the second pressure regulating unit 150 switches to an open state in a case where the negative pressure becomes stronger than a predetermined value. In other words, even if the flow rate of the pump changes due to a change in viscosity caused by an environmental change or the like, as long as the meniscus does not collapse or a predetermined negative pressure is maintained, the communication port 191B can be in a closed state even if the circulation pump 500 is driven.

[0122] Next, an explanation will be given of an example in which the bypass passage 160 is provided so as to supply ink to the pressure chamber 12 from both the supply passage 130 and the collection passage 140. The pressure in the circulation path can fluctuate due to the ejection operation of the ejection element 15. This is because the ejection operation generates a force that sucks ink into the pressure chamber.

[0123] In the following, an explanation will be given of the fact that, in the case of continuing high-duty printing, ink to be supplied to the pressure chamber 12 is supplied from both the supply passage 130 side and the collection passage 140 side. Although the definition of "duty" can vary depending on various conditions, in the following, the state in which a single 4pl ink droplet is printed in a 1200 dpi grid cell will be considered to be 100%. "High-duty printing" is printing performed, for example, at a duty of 100%.

[0124] In the case of continuing high-duty printing, the amount of ink flowing from the pressure chamber 12 into the second pressure control chamber 152 through the collection passage 140 decreases. On the other hand, the circulation pump 500 causes ink to flow out at a constant amount. This disrupts the balance between the inflow and the outflow with respect to the second pressure control chamber 152. Therefore, the ink inside the second pressure control chamber 152 decreases, and the negative pressure in the second pressure control chamber 152 becomes stronger, so that the second pressure control chamber 152 contracts. As the negative pressure in the second pressure control chamber 152 becomes stronger and stronger, the amount of ink entering the second pressure control chamber 152 through the bypass passage 160 increases, and the second pressure control chamber 152 becomes stable in a state in which the inflow and the outflow are balanced. Therefore, the negative pressure in the second pressure control chamber 152 becomes stronger in accordance with the duty. In addition, in the configuration in which the communication port 191B is in the closed state in the case where the circulation pump 500 is driven, as described above, the communication port 191B switches to the open state in accordance with the duty, so that ink flows into the second pressure control chamber 152 from the bypass passage 160.

[0125] In addition, as the high duty cycle printing is further continued, the inflow amount from the pressure chamber 12 into the second pressure control chamber 152 through the collection channel 140 decreases, and, on the contrary, the inflow amount from the communication port 191B into the second pressure control chamber 152 through the bypass channel 160 increases. As this state further progresses, the amount of ink flowing from the pressure chamber 12 into the second pressure control chamber 152 through the collection channel 140 reaches zero, so that the ink flowing from the communication port 191B is the entire ink flowing out into the circulation pump 500. As this state further progresses, the ink from the second pressure control chamber 152 flows back into the pressure chamber 12 through the collection channel 140. In this state, the ink flowing from the second pressure control chamber 152 into the circulation pump 500 and the ink flowing from the second pressure control chamber 152 into the pressure chamber 12 will flow into the second pressure control chamber 152 from the communication port 191B through the bypass channel 160. In this case, the ink from the supply channel 130 and the ink from the collection channel 140 are filled into the pressure chamber 12 and ejected from the pressure chamber 12.

[0126] Note that this ink backflow occurring in the case where the printing duty cycle is high is a phenomenon occurring due to the installation of the bypass channel 160. In addition, as described above, the example in which the communication port 191B in the second pressure adjustment unit switches to the open state for ink backflow has been described. However, ink backflow can also occur in the state where the communication port 191B in the second pressure adjustment unit is in the open state. In addition, in a configuration without the second pressure adjustment unit, the above ink backflow can also occur by installing the bypass channel 160.

[0127] <Configuration of the ejection unit>

[0128] FIG. 11A and FIG. 11B is a schematic view showing the circulation path of ink of one color in the ejection unit 3 in the present embodiment. FIG. 11A is an exploded perspective view of the ejection unit 3 seen from the first support member 4 side. FIG. 11B is an exploded perspective view of the ejection unit 3 seen from the ejection module 300 side. Note that, in FIG. 11A and FIG. 11B the arrows denoted as "in" and "out" indicate ink flow, and the ink flow will be described for only one color, but the ink of the other colors flows similarly. In addition, in FIG. 11A and FIG. 11B the second support member 7 and the electric wiring member 5 are omitted from the drawings, and their description is also omitted in the following description of the configuration of the ejection unit. In addition, for the first support member 4 in FIG. 11A a cross section along the line XI-XI in FIG. 3A is shown. Each ejection module 300 includes an ejection element substrate 340 and an opening plate 330. FIG. 12is a view showing the opening plate 330. FIG. 13 is a view showing the ejection element substrate 340.

[0129] The ink is supplied to the ejection unit 3 from the circulation unit 54 (see FIG. 3A ) via the bonding member 8. The ink path for the ink that returns to the bonding member 8 after passing through the bonding member 8 will now be explained. Note that the illustration of the bonding member 8 is omitted in the drawings to be mentioned below.

[0130] Each ejection module 300 includes the ejection element substrate 340 as a silicon substrate 310 and the opening plate 330, and further includes the ejection port forming member 320. The ejection element substrate 340, the opening plate 330, and the ejection port forming member 320 are formed into the ejection module 300 by being stacked and bonded in such a manner that the ink passages communicate with each other. The ejection module 300 is supported on the first support member 4. The ejection unit 3 is formed by supporting the ejection modules 300 on the first support member 4. The ejection element substrate 340 includes the ejection port forming member 320, and the ejection port forming member 320 includes a plurality of ejection port rows each of which is a plurality of ejection ports 13 formed in a row. A part of the ink supplied through the ink passage in the ejection module 300 is ejected from the ejection ports 13. The ink that is not ejected is collected through the ink passage in the ejection module 300.

[0131] As shown in FIG. 11A , FIG. 11B and FIG. 12 , the opening plate 330 includes a plurality of ink supply ports 311 arranged in a row and a plurality of ink collection ports 312 arranged in a row. As shown in FIG. 13 and FIG. 14A to FIG. 14C , the ejection element substrate 340 includes a plurality of supply connection passages 323 arranged in a row and a plurality of collection connection passages 324 arranged in a row. The ejection element substrate 340 further includes a common supply passage 18 that communicates with the plurality of supply connection passages 323 and a common collection passage 19 that communicates with the plurality of collection connection passages 324. The ink supply passage 48 and the ink collection passage 49 (see FIG. 3A and FIG. 3B ) arranged in the first support member 4 communicate with the passages arranged in each ejection module 300 to form the ink passage inside the ejection unit 3. The support member supply port 211 is an opening in a cross section that forms the ink supply passage 48. The support member collection port 212 is an opening in a cross section that forms the ink collection passage 49.

[0132] The ink to be supplied to the ejection unit 3 is supplied to the ink supply passage 48 (see FIG. 3A ) in the first support member 4 from the circulation unit 54 (see FIG. 3A ) side. The ink that flows through the support member supply port 211 in the ink supply passage 48 passes through the ink supply passage 48 (seeFIG. 3A ) and the ink supply port 311 in the opening plate 330 is supplied to the common supply passage 18 in the ejection element substrate 340, and enters the supply connection passage 323. The passages up to this point are all supply-side passages. Thereafter, the ink passes through the pressure chamber 12 (see FIG. 3B ) in the ejection port formation member 320 and flows into the collection connection passage 324 of the collection-side passages. Details of the ink flow in the pressure chamber 12 will be described below.

[0133] In the collection-side passages, the ink that entered the collection connection passage 324 flows into the common collection passage 19. Thereafter, the ink flows from the common collection passage 19 through the ink collection port 312 in the opening plate 330 into the ink collection passage 49 in the first support member 4, and is collected into the circulation unit 54 through the support member collection port 212.

[0134] The regions of the opening plate 330 in which the ink supply port 311 or the ink collection port 312 is not present correspond to the regions of the first support member 4 for separating the support member supply port 211 and the support member collection port 212. In addition, the first support member 4 does not have openings at these regions. In the case of bonding the ejection module 300 and the first support member 4, such regions serve as bonding regions.

[0135] In the FIG. 12 , a plurality of opening columns arranged along the X direction are provided side by side in the Y direction in the opening plate 330, and the supply (IN) openings and the collection (OUT) openings are alternately arranged in the Y direction in a state in which they are offset from each other by half a pitch in the X direction. In the FIG. 13 , in the ejection element substrate 340, the common supply passages 18 and the common collection passages 19 are alternately arranged in the X direction, the common supply passages 18 communicate with the plurality of supply connection passages 323 arranged in the Y direction, and the common collection passages 19 communicate with the plurality of collection connection passages 324 arranged in the Y direction. The common supply passages 18 and the common collection passages 19 are separated by ink type. In addition, the number of ejection port columns used for each color determines the number of common supply passages 18 and common collection passages 19 to be arranged. In addition, the number of supply connection passages 323 arranged and the number of collection connection passages 324 arranged correspond to the number of ejection ports 13. Note that one-to-one correspondence is not necessarily necessary, and a single supply connection passage 323 and a single collection connection passage 324 can correspond to a plurality of ejection ports 13.

[0136] Each ejection module 300 is formed by stacking and joining the opening plate 330 and the ejection element substrate 340 in such a manner that the ink passages communicate with each other as described above, and each ejection module 300 is supported on the first support member 4. As a result, ink passages including the supply passages and the collection passages as described above are formed.

[0137] FIG. 14A to FIG. 14C is a cross-sectional view showing the flow of ink at different parts of the ejection unit 3. FIG. 14A is a cross section taken along FIG. 11A line XIVA-XIVA in FIG. 14A, and shows a cross section of a portion of the ejection unit 3 at which the ink supply channel 48 and the ink supply port 311 communicate with each other. FIG. 14B is a cross section taken along FIG. 11A line XIVB-XIVB in FIG. 14B, and shows a cross section of a portion of the ejection unit 3 at which the ink collection channel 49 and the ink collection port 312 communicate with each other. In addition, FIG. 14C is a cross section taken along FIG. 11A line XIVC-XIVC in FIG. 14C, and shows a cross section of a portion at which the ink supply port 311 and the ink collection port 312 do not communicate with the channels in the first support member 4.

[0138] As shown in FIG. 14A , the supply channel for supplying ink supplies ink from a portion in the first support member 4 in which the ink supply channel 48 and the ink supply port 311 in the opening plate 330 overlap and communicate with each other. In addition, as shown in FIG. 14B , the collection channel for collecting ink collects ink from a portion in the first support member 4 in which the ink collection channel 49 and the ink collection port 312 in the opening plate 330 overlap and communicate with each other. In addition, as shown in FIG. 14C , the ejection unit 3 partially has a region in which no opening is provided in the opening plate 330. At such a region, neither ink is supplied nor collected between the ejection element substrate 340 and the first support member 4. As shown in FIG. 14A , ink is supplied at a region in which the ink supply port 311 is provided. As shown in FIG. 14B , ink is collected at a region in which the ink collection port 312 is provided. Note that the present embodiment has been described by taking the configuration using the opening plate 330 as an example, but a configuration not using the opening plate 330 can be employed. For example, a configuration in which channels corresponding to the ink supply channel 48 and the ink collection channel 49 are formed in the first support member 4, and the ejection element substrate 340 is bonded to the first support member 4 can be employed.

[0139] FIG. 15A and FIG. 15B are cross-sectional views showing the vicinity of the ejection port 13 in the ejection module 300. FIG. 16A and FIG. 16B are cross-sectional views showing an ejection module of a configuration in which the common supply channel 18 and the common collection channel 19 are widened in the X direction as a comparative example. Note that FIG. 15A and FIG. 15B and FIG. 16A and FIG. 16BThe thick arrow shown in the common supply channel 18 and the common collection channel 19 in FIG. 17 indicates the oscillation movement of the ink occurring in the configuration using the serial liquid ejection apparatus 50. As the ejection element 15 is driven, the ink supplied to the pressure chamber 12 through the common supply channel 18 and the supply connection channel 323 is ejected from the ejection port 13. In the case where the ejection element 15 is not driven, the ink is collected from the pressure chamber 12 into the common collection channel 19 through the collection connection channel 324 which is a collection channel.

[0140] In the case where the ink circulating as above is ejected in the configuration using the serial liquid ejection apparatus 50, the oscillation movement of the ink inside the ink channel caused by the main scanning of the liquid ejection head 1 has not a small degree of influence on the ejection of the ink. Specifically, the influence of the oscillation movement of the ink inside the ink channel appears as a difference in the amount of the ejected ink and a deviation in the ejection direction. As FIG. 16A and FIG. 16B indicated, in the case where the common supply channel 18 and the common collection channel 19 have a cross-sectional shape wide in the X direction which is the main scanning direction, the ink inside the common supply channel 18 and the common collection channel 19 is more easily subjected to the inertial force in the main scanning direction, so that the ink greatly oscillates. This causes the oscillation movement of the ink to possibly affect the ejection of the ink from the ejection port 13. In addition, the widening of the common supply channel 18 and the common collection channel 19 in the X direction makes the distance between the colors wide. This can reduce the printing efficiency.

[0141] Therefore, each common supply channel 18 and each common collection channel 19 in the present embodiment (the cross sections of which are shown in FIG. 15A and FIG. 15B ) have a configuration in which each common supply channel 18 and each common collection channel 19 each extend in the Y direction and also extend in the Z direction which is perpendicular to the X direction which is the main scanning direction. In the case of such a configuration, the common supply channel 18 and the common collection channel 19 are given a small channel width in the main scanning direction. By giving the common supply channel 18 and the common collection channel 19 a small channel width in the main scanning direction, the oscillation movement of the ink inside the common supply channel 18 and the common collection channel 19 caused by the inertial force applied to the ink and in the direction opposite to the main scanning direction (the black thick arrow in FIG. 15A and FIG. 15B ) during the main scanning becomes small. This reduces the influence of the oscillation movement of the ink at the time of the ejection of the ink. In addition, by extending the common supply channel 18 and the common collection channel 19 in the Z direction, the cross-sectional area of the common supply channel 18 and the common collection channel 19 is made large. This reduces the channel pressure drop.

[0142] As described above, each common supply passage 18 and each common collection passage 19 are given a small passage width in the main scanning direction. This configuration reduces the oscillatory motion of ink inside the common supply passage 18 and the common collection passage 19 during main scanning, but cannot eliminate the oscillatory motion. Therefore, in the present embodiment, in order to reduce the ejection difference between ink types that can be caused by the reduced oscillatory motion, the configuration is such that the common supply passage 18 and the common collection passage 19 are arranged at positions that overlap each other in the X direction.

[0143] As described above, in the present embodiment, the supply connection passages 323 and the collection connection passages 324 are provided in a manner corresponding to the ejection ports 13. In addition, the correspondence between the supply connection passages 323 and the collection connection passages 324 is established such that the supply connection passages 323 and the collection connection passages 324 are arranged in the X direction with the ejection ports 13 interposed therebetween. Therefore, if the common supply passage 18 and the common collection passage 19 have a portion(s) in which the common supply passage 18 and the common collection passage 19 do not overlap each other in the X direction, the correspondence between the supply connection passages 323 and the collection connection passages 324 in the X direction is interrupted. This inconsistency affects the ink ejection and the flow of ink in the pressure chamber 12 in the X direction. If this inconsistency is combined with the effect of the oscillatory motion of ink, the ink ejection from each ejection port can be further affected.

[0144] Therefore, by arranging the common supply passage 18 and the common collection passage 19 at positions that overlap each other in the X direction, the oscillatory motion of ink inside the common supply passage 18 and the common collection passage 19 during main scanning is substantially the same at any position in the Y direction in which the ejection ports 13 are arranged. Therefore, between the common supply passage 18 side and the common collection passage 19 side, the pressure difference generated in the pressure chamber 12 does not greatly fluctuate. These low pressure differences make stable ejection possible.

[0145] Further, some liquid ejection heads that circulate ink therein are configured such that a channel for supplying ink to the liquid ejection head and a channel for collecting ink are the same channel. However, in the present embodiment, the common supply channel 18 and the common collection channel 19 are different channels. Further, the supply connection channel 323 and the pressure chamber 12 communicate with each other, the pressure chamber 12 and the collection connection channel 324 communicate with each other, and ink is ejected from the ejection port 13 in the pressure chamber 12. That is, a configuration is formed in which the pressure chamber 12 that serves as a path connecting the supply connection channel 323 and the collection connection channel 324 includes the ejection port 13. Therefore, in each pressure chamber 12, a flow of ink flowing from the supply connection channel 323 side to the collection connection channel 324 side is generated, and ink inside the pressure chamber 12 is efficiently circulated. By efficiently circulating the ink inside the pressure chamber 12, the ink inside the pressure chamber 12 that is susceptible to evaporation of ink from the ejection port 13 is kept fresh.

[0146] Further, since two channels (i.e., the common supply channel 18 and the common collection channel 19) communicate with the pressure chamber 12, in a case where it is necessary to perform ejection (become available for supply) at a high flow rate, ink can be supplied from both channels. That is, compared with a configuration in which only a single channel is formed for ink supply and collection, the configuration in the present embodiment has the advantage that not only efficient circulation can be performed, but also ejection at a high flow rate can be dealt with.

[0147] Incidentally, in a case where the common supply channel 18 and the common collection channel 19 are arranged at positions close to each other in the X direction, the oscillatory motion of ink causes less influence. It is desirable that the common supply channel 18 and the common collection channel 19 be arranged such that the gap between these channels is 75 μm to 100 μm.

[0148] FIG. 17 is a view that shows an ejection element substrate 340 as a comparative example. Note that the illustration of the supply connection channel 323 and the collection connection channel 324 is omitted in FIG. 17 . Ink that has received thermal energy from the ejection element 15 in the pressure chamber 12 flows into the common collection channel 19. Therefore, the temperature of the ink flowing through the common collection channel 19 is higher than the temperature of the ink in the common supply channel 18. Here, in the comparative example, as indicated by a portion a encircled with a dotted line in FIG. 17 , at a portion in the X direction of the ejection element substrate 340, only the common collection channel 19 is present. In this case, the temperature can locally rise at the portion, resulting in temperature unevenness within the ejection module 300. This temperature unevenness can affect ejection.

[0149] The temperature of the ink flowing through the common supply passage 18 is lower than the temperature of the ink in the common collection passage 19. Therefore, if the common supply passage 18 and the common collection passage 19 are close to each other, the ink in the common supply passage 18, which is relatively low in temperature, lowers the temperature of the ink in the common collection passage 19 at the point where the two passages are close to each other.

[0150] This suppresses the temperature rise. To this end, it is preferable that the common supply passage 18 and the common collection passage 19 have substantially the same length, exist at a position overlapping each other in the X direction, and be close to each other.

[0151] FIG. 18A and FIG. 18B is a diagram showing the passage configuration of the liquid ejection head 1 used for inks of three colors of cyan (C), magenta (M), and yellow (Y). In the liquid ejection head 1, as shown in FIG. 18A , a circulation passage is provided for each ink type. The pressure chamber 12 is provided along the X direction, which is the main scanning direction of the liquid ejection head 1. In addition, as shown in FIG. 18B , the common supply passage 18 and the common collection passage 19 are provided along the ejection port column, which is the column of ejection ports 13. The common supply passage 18 and the common collection passage 19 are provided in a manner extending in the Y direction, with the ejection port column being located between the common supply passage 18 and the common collection passage 19.

[0152] <Connection between main body and liquid ejection head>

[0153] FIG. 19 is a schematic configuration diagram showing the connection state between the ink cartridge 2 and the external pumps 21 provided in the main body of the liquid ejection apparatus 50 and the liquid ejection head 1 and the placement of the circulation pumps in the present embodiment in more detail. The liquid ejection apparatus 50 in the present embodiment has a configuration in which the liquid ejection head 1 can be easily replaced alone in the case where a failure occurs in the liquid ejection head 1. Specifically, the liquid ejection apparatus 50 in the present embodiment has a liquid connection portion 700 in which the respective ink supply tubes 59 connected to the respective external pumps 21 and the liquid ejection head 1 can be easily connected and disconnected to each other. This makes it possible for the liquid ejection head 1 alone to be easily mounted to and detached from the liquid ejection apparatus 50.

[0154] As shown in FIG. 19As shown, the liquid connection portion 700 has a liquid connector insertion port 53a provided in a protruding manner on the head case 53 of the liquid ejection head 1, and a cylindrical liquid connector 59a into which the liquid connector insertion port 53a is insertable. The liquid connector insertion port 53a is fluidically connected to an ink supply channel formed in the liquid ejection head 1, and is connected to the first pressure adjusting unit 120 via the above-described filter 110. The liquid connector 59a is arranged at a front end of an ink supply tube 59 connected to the external pump 21 that supplies the ink in the ink cartridge 2 to the liquid ejection head 1 by pressurization.

[0155] As described above, FIG. 19 The liquid ejection head 1 shown in FIG. 6 can be used to easily mount, detach, and replace the liquid ejection head 1 by the liquid connection portion 700. However, when the sealing performance between the liquid connector insertion port 53a and the liquid connector 59a deteriorates, the ink supplied under pressure by the external pump 21 can leak from the liquid connection portion 700. If the leaked ink adheres to the circulation pump 500 or the like, a malfunction can occur in the electrical system. Therefore, in this embodiment, the circulation pump or the like is configured as follows.

[0156] <Placement of the circulation pump or the like>

[0157] As FIG. 19 shown in FIG. 6, in this embodiment, in order to avoid the ink leaked from the liquid connection portion 700 from adhering to the circulation pump 500, the circulation pump 500 is arranged higher than the liquid connection portion 700 in the direction of gravity. Specifically, the circulation pump 500 is arranged higher than the liquid connector insertion port 53a, which is the liquid inlet in the liquid ejection head 1, in the direction of gravity. In addition, the circulation pump 500 is arranged at a position where the constituent members of the liquid connection portion 700 do not come into contact with the circulation pump 500. In this way, even if the ink leaks from the liquid connection portion 700, the ink flows in the horizontal direction as the opening direction of the opening that is the liquid connector 59a or flows downward in the direction of gravity. This prevents the ink from reaching the circulation pump 500, which is located at a higher position in the direction of gravity. In addition, arranging the circulation pump 500 at a position separate from the liquid connection portion 700 also reduces the possibility of the ink reaching the circulation pump 500 via the members.

[0158] Further, an electrical connection portion 515, through which the flexible wiring member 514 is electrically connected between the circulation pump 500 and the electrical contact substrate 6, is provided higher than the liquid connection portion 700 in the direction of gravity. Therefore, even in the case where the ink leaks from the liquid connection portion 700, the possibility of the ink causing an electrical malfunction is reduced.

[0159] Further, in the present embodiment, since the wall portion 53b of the head case 53 is provided, even if ink is ejected from the opening 59b of the liquid connection portion 700, the ink is blocked and the possibility of the ink reaching the circulation pump 500 and the electrical connection portion 515 can be reduced.

[0160] The features of the present embodiment will be described below. In the liquid ejecting head 1 of the present embodiment, the common supply passage 18 and the common collection passage 19 are provided as independent passages along the arrangement direction of the ejection ports. Further, ink is supplied from the supply connection passage 323 communicating with the common supply passage 18 to the pressure chamber 12, and is ejected from the pressure chamber 12 through the ejection port 13. Ink not ejected from the pressure chamber 12 is collected from the pressure chamber 12 through the collection connection passage 324 and the common collection passage 19. In the case of such a configuration, a pressure difference is easily generated in each pressure chamber 12 between the supply side and the collection side. Therefore, the ink circulation efficiency is high at each pressure chamber 12. Further, as the ejection element 15 is driven, most of the circulated ink in the pressure chamber 12 is ejected from the ejection port 13. This makes it possible to efficiently replace the ink in the ejection port 13. The common supply passage 18 and the common collection passage 19 are configured to have substantially the same length as the length of the ejection port row. Note that substantially the same length means that the length of the common collection passage 19 is 0.95 to 1.05 times the length of the common supply passage 18.

[0161] In the liquid ejecting head 1 of the present embodiment, the common supply passage 18 and the common collection passage 19 are provided as independent passages, and both are connected to the pressure chamber 12. In this way, it is possible to suppress the deterioration of the ink circulation efficiency in the vicinity of the ejection port. Note that the vicinity of the ejection port here is a region including the ejection port 13 and the pressure chamber 12.

[0162] The features of the liquid ejecting head 1 will now be described. In the liquid ejecting head 1 of the present embodiment, the common supply passage 18 and the common collection passage 19 are provided along the arrangement direction of the ejection ports, with the ejection port row being positioned between the common supply passage 18 and the common collection passage 19. Further, by flowing the ink in the X direction as the main scanning direction, the ink is circulated through the pressure chamber 12. Note that in the case where the angle formed between the flow direction of the liquid in the pressure chamber and the main scanning direction is 10 degrees or less, the liquid is considered to flow through the pressure chamber along the main scanning direction. It is preferable that the flow direction of the liquid in the pressure chamber and the main scanning direction be parallel. Further, the extension direction of the pressure chamber can be considered to be the flow direction of the liquid in the pressure chamber, unless a special liquid is supplied.

[0163] In general liquid ejecting heads, the common passages through which ink is supplied and collected are circulation passages provided along the nozzle row, and ink is circulated along the nozzle row. In these general liquid ejecting heads, the length of the circulation passage is set to be greater than the length of the nozzle row, taking into account the flow of ink in the nozzles at the opposite ends of the nozzle row. This can lead to the possibility of increasing the size of the liquid ejecting head in the direction along the nozzle row and thus the size of the apparatus.

[0164] However, because ink is caused to flow through the pressure chambers 12 in the X direction as the main scanning direction, the common supply passage 18 and the common collection passage 19 do not need to be provided to be longer than the length of the nozzle row. Therefore, the ejecting element substrate 340 can be made shorter in the direction along the nozzle row. This can prevent the apparatus from being large-sized.

[0165] (Variation)

[0166] FIG. 20A and FIG. 20B is a view showing the passage configuration of the liquid ejecting head 1 for three colors of ink in the variation. The flow paths in the liquid ejecting head 1 in the variation are connected so that the ink types are line-symmetrical about the dashed-dotted line CL. Specifically, in the liquid ejecting head 1 in the variation, the common supply passage 18 and the common collection passage 19 are line-symmetrical about the dashed-dotted line CL. FIG. 20A In the variation, the ink is arranged in the order of C, M, and Y from the left in the ejecting module 300L, and the ink is arranged in the order of Y, M, and C from the left in the ejecting module 300R. In the case of this configuration, in the scanning operation, the order of ink ejection is not different between the forward scanning and the reverse scanning. This keeps the color tone of the image constant.

[0167] In addition, the ejecting modules 300L and 300R differ in the direction of ink circulation in the pressure chambers 12. Specifically, in the two ejecting modules 300L and 300R, the direction of ink circulation in the pressure chambers 12 is the direction toward the dashed-dotted line CL.

[0168] In the scanning operation, the liquid ejecting head 1 reciprocates in the forward and reverse directions. Therefore, there are a period in which the direction of ink circulation in each pressure chamber 12 and the main scanning direction are the same direction and a period in which they are opposite directions. Then, due to the oscillatory motion of the ink, the pressure in the pressure chamber 12 can differ between the period in which the direction of ink circulation and the main scanning direction are the same direction and the period in which they are opposite directions, and printing unevenness can occur.

[0169] To solve this problem, the liquid ejecting head 1 in the variation is configured so that the directions of ink circulation through the pressure chambers 12 in the ejecting module 300L and the ejecting module 300R are line-symmetrical about the dashed-dotted line CL. In this way, the pressure difference is canceled out. This prevents printing unevenness that would otherwise occur due to the reciprocating motion.

[0170] In addition, in the case of a configuration that is line-symmetrical in the circulation direction, the innermost ink is the same line (both are "OUT"). In this way, the design can be simplified by, for example, combining the passages of the same line. Thus, it is possible to downsize.

[0171] (Other Embodiments)

[0172] FIG. 21 Fig. 1 is a diagram showing a liquid ejection head 1 in another embodiment. The liquid ejection head 1 in the present embodiment includes a single ejection module 300. The configuration of the liquid ejection head 1 can be such that it includes the single ejection module 300 as above.

[0173] In addition, as in this modification, in the single ejection module 300, the ejection port row and the circulation passage can be provided to be line-symmetrical. Further, the configuration can be such that the flow direction of the liquid in the pressure chamber 12 is line-symmetrical.

[0174] In addition, two or more ejection modules 300 can be included.

[0175] While the present application has been described with reference to exemplary embodiments, it is to be understood that the application is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be construed in the broadest sense to encompass all such alterations, equivalents, and functions.

Claims

1. A liquid ejection head that ejects liquid in a process of moving along a main scanning direction, the liquid ejection head comprising: an ejection module that has a plurality of ejection ports through which the liquid can be ejected with operation of an energy generating element; and a circulation unit configured to circulate the liquid by supplying the liquid to the ejection module and collecting the liquid from the ejection module, characterized in that the ejection module has: a pressure chamber that communicates with the ejection ports; a supply passage through which the liquid is supplied to the pressure chamber; and a collection passage that is provided separately from the supply passage and through which the liquid is collected from the pressure chamber, and the liquid flows through the pressure chamber along the main scanning direction, wherein the liquid ejection head is configured to be able to supply the liquid from the collection passage to the pressure chamber.

2. The liquid ejection head according to claim 1, wherein in the ejection module, the plurality of ejection ports form an ejection port row in an ejection port face, the ejection port row forms a row in a direction that intersects the main scanning direction, and the supply passage and the collection passage are provided along the ejection port row, the ejection port row is positioned between the supply passage and the collection passage when viewed from an up-down direction that perpendicularly intersects the ejection port face.

3. The liquid ejection head of claim 2, wherein The supply passage and the collection passage have lengths that are substantially the same as a length of the ejection port row.

4. The liquid ejection head according to claim 1, wherein the pressure chamber is provided in a relationship corresponding to the ejection ports, the supply passage is provided in a relationship corresponding to the pressure chamber, and the supply passage is connected to a supply connection passage that is connected to the pressure chamber, and the collection passage is provided in a relationship corresponding to the pressure chamber, and the collection passage is connected to a collection connection passage that is connected to the pressure chamber.

5. The liquid ejection head according to claim 2, wherein the ejection module includes a plurality of the ejection port rows, the plurality of the ejection port rows are provided to be line-symmetrical about a line that is parallel to an arrangement direction of ejection ports of the ejection port row, and a type of liquid to be ejected from the ejection ports of the ejection port row is line-symmetrical about the line.

6. The liquid ejection head according to claim 2, wherein a plurality of the ejection modules are included in the same plane, the plurality of the ejection modules are provided to be line-symmetrical about a line that is parallel to an arrangement direction of ejection ports of the ejection port row, and a type of liquid to be ejected from the ejection ports of the ejection port row is line-symmetrical about the line.

7. The liquid ejection head of claim 5, wherein A flow direction of the liquid in the pressure chamber is a direction toward the line.

8. A liquid ejection apparatus comprising: a liquid ejection unit configured to eject liquid; a moving unit configured to move the liquid ejection unit along a main scanning direction; an ejection module that has a plurality of ejection ports through which the liquid can be ejected with operation of an energy generating element; and a circulation unit configured to circulate the liquid by supplying the liquid to the ejection module and collecting the liquid from the ejection module. a circulating unit configured to circulate the liquid by supplying the liquid to the ejection module and collecting the liquid from the ejection module, characterized in that the ejection module has: a pressure chamber communicating with the ejection port; a supply passage through which the liquid is supplied to the pressure chamber; and a collection passage provided separately from the supply passage and through which the liquid is collected from the pressure chamber, and the liquid flows through the pressure chamber along the main scanning direction, wherein the liquid ejection apparatus is configured to be capable of supplying the liquid from the collection passage to the pressure chamber.

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