Liquid ejecting head and liquid ejecting apparatus

Abstract

The present disclosure relates to a liquid ejection head and a liquid ejection apparatus. A liquid ejection head includes a pressure chamber, an upstream channel, a downstream channel, a pump, an inflow channel, and a bypass channel. The upstream channel communicates with the pressure chamber to supply liquid to the pressure chamber. The downstream channel communicates with the pressure chamber. The pump communicates with the upstream channel and the downstream channel to cause liquid in the downstream channel to flow into the upstream channel. The inflow channel communicates with the upstream channel to cause liquid to be supplied to the pressure chamber to flow into the upstream channel. The upstream channel and the downstream channel communicate with each other through the bypass channel without the pressure chamber between the upstream channel and the downstream channel. A portion of liquid flowing from the upstream channel into the bypass channel flows into the pressure chamber through the downstream channel.

Description

Technical Field

[0001] This disclosure relates to liquid jet heads and liquid jetting devices including liquid jet heads. Background Technology

[0002] A circulating liquid jetting device is known, which circulates liquid between a liquid jet head and a liquid storage unit to expel air bubbles in the channel and suppress ink thickening near the jet nozzle. The circulating liquid jetting device includes a device that circulates liquid between the liquid jet head and the body using a body-side pump located outside the liquid jet head, and a device that circulates liquid inside the liquid jet head using a pump located inside the liquid jet head.

[0003] Japanese Patent Application Publication No. 2014-195932 (hereinafter referred to as Document 1) discloses a liquid jetting device in which a piezoelectric circulating pump is installed in a liquid jetting head to circulate ink within the liquid jetting head. In the configuration of Document 1, ink supplied from the circulating pump to the pressure control mechanism is then supplied to the pressure chamber through the ink supply channel, and unjetted ink is collected back to the circulating pump through the ink collection channel.

[0004] For example, in Reference 1, the ink supplied to the pressure chamber is only supplied from the pressure control mechanism through the ink supply channel. That is, the ink is not supplied to the pressure chamber via the ink collection channel. This is because the circulation pump that circulates the ink is equipped with a check valve, thus ensuring that the ink circulates through the circulation channel in only one direction. Therefore, if, for example, the ink ejection volume increases, the amount of ink to be supplied to the ejection nozzle decreases, which may lead to a reduction in ejection stability. Summary of the Invention

[0005] According to one aspect of this disclosure, a liquid injection head includes: a pressure chamber in which pressure generated by an injection element configured to generate pressure is applied, wherein the pressure is used to inject liquid from an injection port; an upstream passage communicating with the pressure chamber and configured to supply liquid to the pressure chamber; a downstream passage communicating with the pressure chamber; a pump communicating with the upstream and downstream passages and configured to allow liquid in the downstream passage to flow into the upstream passage; an inflow passage communicating with the upstream passage and configured to allow liquid to be supplied to the pressure chamber to flow into the upstream passage; and a bypass passage through which the upstream and downstream passages are connected to each other without a pressure chamber between the upstream and downstream passages, wherein a portion of the liquid flowing from the upstream passage into the bypass passage flows into the pressure chamber through the downstream passage.

[0006] Further features of this disclosure will become apparent from the following description of exemplary embodiments, with reference to the accompanying drawings. Attached Figure Description

[0007] Figure 1A and1B This is a perspective view and block diagram showing a liquid jetting device.

[0008] Figure 2 These are exploded perspective and top views of the liquid injection head.

[0009] Figure 3A and 3B These are vertical cross-sectional views of the liquid injection head and enlarged cross-sectional views of the injection module.

[0010] Figure 4 This is a schematic diagram of the appearance of the loop unit.

[0011] Figure 5 This is a vertical cross-sectional view showing the loop path.

[0012] Figure 6 It is a schematic diagram illustrating the loop path.

[0013] Figures 7A to 7C This is a cross-sectional view showing an example of a pressure regulating unit.

[0014] Figure 8A and 8B This is a perspective view of the circulating pump.

[0015] Figure 9 yes Figure 8A The diagram shows a cross-sectional view of the circulating pump along line IX-IX.

[0016] Figures 10A to 10E It is a diagram depicting the ink flow inside a liquid jet nozzle.

[0017] Figure 11A and 11B This is a schematic diagram showing the circulation path in the injection unit.

[0018] Figure 12 This is a view showing the opening plate.

[0019] Figure 13 This is a view showing the substrate of the spray element.

[0020] Figures 14A to 14C This is a cross-sectional view showing the ink flow in the jetting unit.

[0021] Figure 15A and 15B This is a cross-sectional view showing the area near the injection nozzle.

[0022] Figure 16A and 16B This is a cross-sectional view showing a comparative example near the injection nozzle.

[0023] Figure 17 This is a view showing a comparative example of a jetting element substrate.

[0024] Figure 18A and 18B This is a view showing the channel structure of the liquid jet head.

[0025] Figure 19 This is a view showing the connection status between the main unit of the liquid injection device and the liquid injection head.

[0026] Figure 20A and 20B This is a schematic view showing the ink backflow near the nozzle;

[0027] Figure 21A and 21B This is a view describing the ink supply inside the jetting module;

[0028] Figure 22A and 22B It is a schematic view illustrating the loop path;

[0029] Figure 23A and 23B It is a schematic view illustrating the loop path;

[0030] Figure 24A and 24B It is a schematic view illustrating the loop path;

[0031] Figure 25A and 25B It is a schematic view illustrating the loop path;

[0032] Figure 26 It is a schematic diagram illustrating the loop path;

[0033] Figure 27 It is a schematic diagram illustrating the loop path;

[0034] Figure 28 It is a schematic diagram illustrating the loop path;

[0035] Figure 29 It is a schematic view illustrating the loop path; and

[0036] Figure 30 This is a schematic view illustrating the loop path. Detailed Implementation

[0037] Preferred embodiments of the present disclosure will be described in detail 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 these embodiments are necessary for the present disclosure. Note that the same constituent elements are denoted by the same reference numerals. This embodiment will be described using an example in which a thermal jetting element that generates bubbles by utilizing an electrothermal conversion element to spray liquid is used as each jetting element for spraying liquid; however, this embodiment is not limited to this example. This embodiment is also applicable to liquid jetting heads employing jetting methods using piezoelectric elements, as well as liquid jetting heads employing other jetting methods. Furthermore, the pumps, pressure regulating units, etc., described below are not limited to the constructions described in the embodiments and shown in the drawings. In the following description, the basic structure of the present disclosure will be discussed first, followed by the description of the distinctive features of the present disclosure.

[0038] <Liquid jetting equipment>

[0039] Figure 1A This is a view used to describe a liquid injection device; it is an enlarged view of the liquid injection head and its surroundings. First, refer to... Figure 1A and 1B A schematic construction of the liquid jetting device 50 in this embodiment is described. Figure 1A This is a perspective view schematically showing a liquid jetting device using a liquid jetting head 1. The liquid jetting device 50 in this embodiment is configured as a tandem inkjet printing device that performs printing on a printing medium P by jetting ink as a liquid while scanning the liquid jetting head 1.

[0040] The liquid jet head 1 is mounted on a carrier 60. The carrier 60 reciprocates along a guide shaft 51 in the main scanning direction (X direction). The printing media P is conveyed by transport rollers 55, 56, 57, and 58 in a secondary scanning direction (Y direction) that intersects (in this example, perpendicularly) the main scanning direction. Note that in the figures mentioned below, the Z direction represents the vertical direction and intersects (in this example, perpendicularly) the XY plane defined by the X and Y directions. The liquid jet head 1 is configured to be attachable to and detachable from the carrier 60 by the user.

[0041] Liquid injection head 1 includes circulation unit 54 and injection unit 3, which will be described later (see below). Figure 2 Although the specific construction will be described later, the injection unit 3 includes multiple injection ports and an energy generating element (hereinafter referred to as the "injection element") that generates injection energy for ejecting liquid from the respective injection ports.

[0042] The liquid jetting device 50 also includes an ink tank 2 as an ink source and an external pump 21. Driven by the external pump 21, the ink stored in the ink tank 2 is supplied to the circulation unit 54 through the ink supply pipe 59.

[0043] The liquid jetting device 50 forms a predetermined image on a printing medium P through repeated print scanning and transport operations. The print scanning involves ejecting ink while the liquid jetting head 1, mounted on a carriage 60, moves along the main scanning direction. The transport operation involves transporting the printing medium P along the sub-scanning direction. Note that the liquid jetting head 1 in this embodiment is capable of ejecting four types of ink: black (B), cyan (C), magenta (M), and yellow (Y), and can use these inks to print full-color images. However, the inks that can be ejected from the liquid jetting head 1 are not limited to the four types mentioned above. This invention is also applicable to liquid jetting heads that eject other types of ink. In short, the type and quantity of ink ejected from the liquid jetting head are not limited.

[0044] Furthermore, in the liquid jetting apparatus 50, a cover member (not shown) capable of covering the nozzle surface of the liquid jetting head 1 is provided at a position separated from the transport path for the printing medium P in the X direction, and an nozzle is formed in the nozzle surface. The cover member covers the nozzle surface of the liquid jetting head 1 during non-printing operations and is used to prevent the nozzle from drying out, protect the nozzle, and perform ink suction operations from the nozzle.

[0045] Notice, Figure 1A The liquid ejector head 1 shown represents an example of a liquid ejector head 1 including four circulation units 54 corresponding to four types of ink, but it is sufficient that the included circulation units 54 correspond to the type of liquid to be ejected. Similarly, multiple circulation units 54 may be included for the same type of liquid. In summary, the liquid ejector head 1 may have a configuration including one or more circulation units. The liquid ejector head 1 may be configured to not circulate all four types of ink, but only circulate at least one type of ink.

[0046] Figure 1BThis is a block diagram showing the control system of the liquid jetting device 50. The CPU 103 acts as a control unit, controlling the operation of each unit of the liquid jetting device 50 based on a program such as the processing procedure stored in the ROM 101. The RAM 102 serves as a working area for the CPU 103 to perform processing, etc. The CPU 103 receives image data from a host device 400 external to the liquid jetting device 50 and controls the head driver 1A to control the driving of the jetting elements disposed in the jetting unit 3. The CPU 103 also controls the drivers of various actuators disposed in the liquid jetting device. For example, the CPU 103 controls the motor driver 105A for the carriage motor 105 for moving the carriage 60, the motor driver 104A for the transport motor 104 for transporting the printing media P, etc. Furthermore, the CPU 103 controls the pump driver 500A for the circulation pump 500 (described later), the pump driver 21A for the external pump 21, etc. Note that... Figure 1B The diagram shows a configuration for receiving image data from host device 400 and performing processing, but the liquid jetting device 50 can perform processing regardless of whether data is provided from host device 400.

[0047] <Basic Structure of Liquid Jet Heads>

[0048] Figure 2 These are exploded perspective and top views of the liquid injection head 1 in this embodiment. Figure 3A and 3B yes Figure 2 The liquid jet head 1 shown is a cross-sectional view along the line II IA-II IA. Figure 3A It is a vertical cross-sectional view of the entire liquid injection head 1, and Figure 3B yes Figure 3A The enlarged view of the injection module is shown below. The following will primarily refer to... Figures 2 to 3B and Figure 1A The basic structure of the liquid injection head 1 in this embodiment will be described below.

[0049] like Figure 2 As shown, the liquid ejection head 1 includes a circulation unit 54 and an ejection unit 3 for ejecting ink supplied from the circulation unit 54 onto the printing medium P. In this embodiment, the liquid ejection head 1 is fixedly supported on the bracket 60 of the liquid ejection device 50 by a positioning unit and electrical contacts (not shown) disposed on the bracket 60. The liquid ejection head 1 ejects ink along the... Figure 1A The main scanning direction (X direction) shown moves together with the carriage 60 while ink is ejected to perform printing on the printing medium P.

[0050] The external pump 21 connected to the ink tank 2, which serves as the ink source, includes an ink supply tube 59 (see...). Figure 1AA liquid connector (not shown) is disposed at the end of each of these ink supply tubes 59. With the liquid ejector head 1 installed in the liquid ejection device 50, a liquid connector disposed at the end of the ink supply tube 59 and through which liquid is introduced is sealed to a liquid connector insertion slot 53a disposed on the head housing 53 of the liquid ejector head 1. As a result, an ink supply path is formed extending from the ink tank 2 to the liquid ejector head 1 via the external pump 21. In this embodiment, four types of ink are used. Therefore, four groups are provided for each type of ink, each group including the ink tank 2, the external pump 21, the ink supply tube 59, and the circulation unit 54, and the four ink supply paths corresponding to each type of ink are formed independently of each other. As described above, the liquid ejection device 50 in this embodiment includes an ink supply system that supplies ink from the ink tank 2 disposed outside the liquid ejector head 1 to this ink supply system. Note that the liquid ejection device 50 in this embodiment does not include an ink collection system for collecting ink from the liquid ejector head 1 into the ink tank 2. Therefore, the liquid ejector head 1 includes a liquid connector insertion slot 53a for connecting the ink supply tube 59 of the ink tank 2, but does not include a connector insertion slot for connecting the tube for collecting ink from the liquid ejector head 1 into the ink tank 2. Note that a liquid connector insertion slot 53a is provided for each type of ink.

[0051] exist Figure 3A In the accompanying drawings, reference numerals 54B, 54C, 54M, and 54Y represent the looping units for black, cyan, magenta, and yellow inks, respectively. The looping units have essentially the same structure, and in this embodiment, each looping unit will be referred to as "looping unit 54" unless otherwise specified.

[0052] exist Figure 2 and 3A In the process, the spraying unit 3 includes two spraying modules 300, a first support member 4, a second support member 7, an electrical wiring member (wire strip) 5, and an electrical contact substrate 6. For example... Figure 3B As shown, each spraying module 300 includes a silicon substrate 310 with a thickness of 0.5 mm to 1 mm and a plurality of spraying elements 15 disposed on one surface of the silicon substrate 310. In this embodiment, each spraying element 15 includes an electrothermal conversion element (heater) that generates heat energy as spraying energy for spraying the liquid. Electricity is supplied to each spraying element 15 via wires formed on the silicon substrate 310 using a film deposition technique.

[0053] Furthermore, the outlet forming member 320 is formed on the surface of the silicon substrate 310. Figure 3BOn the lower surface of the ink jetting module 300. In the outlet forming member 320, multiple pressure chambers 12 corresponding to multiple jetting elements 15 and multiple outlets 13 for jetting ink are formed using photolithography. Furthermore, a common supply channel 18 and a common collection channel 19 are formed in the silicon substrate 310. Additionally, 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 ink jetting module 300 is configured to jet two types of ink. Specifically, in... Figure 3A Of the two injection modules shown, the one located in Figure 3A The left-side jetting module 300 jets black and cyan ink, located... Figure 3A The jetting module 300 on the right jets magenta and yellow ink. Note that this combination is merely an example; any ink combination can be used. This configuration allows one jetting module to jet one type of ink or three or more types of ink. The two jetting modules 300 do not need to jet the same amount of ink of the same type. This configuration can include only one jetting module 300, or three or more jetting modules 300. Furthermore, in... Figure 3A and 3B In the example shown, two nozzle arrays extending in the Y direction are formed for ink of one color. Each of the plurality of nozzles 13 forming each nozzle array has a pressure chamber 12, a common supply channel 18, and a common collection channel 19.

[0054] The ink supply port and ink collection port described below are formed on the back side of the silicon substrate 310. Figure 3B (On the upper surface of the middle). Ink is supplied from ink supply channel 48 to multiple common supply channels 18 through ink supply port. Ink is collected from multiple common collection channels 19 into collection channel 49 through ink collection port.

[0055] Note that the ink supply port and ink collection port correspond to the openings used for supplying and collecting ink during the forward ink circulation process described below. Specifically, during the forward ink circulation, 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 circulation process 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.

[0056] like Figure 3A As shown, the rear surface of the injection module 300 ( Figure 3A The upper surface of the middle part is bonded and fixed to one surface of the first support member 4. Figure 3AThe lower surface of the first support member 4). An ink supply channel 48 and an 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. The opening on one side of the ink supply channel 48 communicates with the aforementioned ink supply port in the silicon substrate 310. The opening on one 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 independently provided for each type of ink.

[0057] In addition, it has an opening 7a (see Figure 2 The second support member 7 of the injection module 300 is bonded and fixed to one surface of the first support member 4. Figure 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 portion of the inkjet module 300 and the electrical wiring component 5 are sealed with a sealant (not shown) to prevent ink corrosion and external impact.

[0058] Furthermore, the electrical contact substrate 6 is bonded to the end 5a of the electrical wiring component 5 by thermo-pressing with an anisotropic conductive film (not shown). Figure 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 jetting device 50.

[0059] In addition, the connecting member 8 ( Figure 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 Figure 3A In this configuration, supply port 88B and collection port 89B are used for black ink, and supply port 88C and collection port 89C are used for cyan ink. Additionally, supply port 88M and collection port 89M are used for magenta ink, and supply port 88Y and collection port 89Y are used for yellow ink.

[0060] Note that the openings at one end of the ink supply channel 48 and the ink collection channel 49 in the first support member 4 have small opening areas that match the ink supply port and ink collection port in the silicon substrate 310. On the other hand, the openings at the other end of the ink supply channel 48 and the ink collection channel 49 in the first support member 4 have large shapes, and their opening areas are the same as the opening areas formed in the bonding member 8, to match the channels in the circulation unit 54. This configuration can suppress the increase in channel resistance of the ink collected from each collection channel. Note that the shapes of the openings at one end and the other end of the ink supply channel 48 and the ink collection channel 49 are not limited to the examples described above.

[0061] In the liquid jet head 1 with the above-described structure, ink supplied to the circulation unit 54 passes through the supply port 88 in the connecting member 8 and the ink supply channel 48 in the first support member 4, and flows from the ink supply port in the jet module 300 into the common supply channel 18. Thereafter, ink flows from the common supply channel 18 into the pressure chamber 12 through the supply connection channel 323. As the jet element 15 is driven, a portion of the ink flowing into the pressure chamber is ejected from the jet port 13. The remaining ink that is not ejected flows from the pressure chamber 12 through the collection connection channel 324 and the common collection channel 19, and flows from the ink collection port into the ink collection channel 49 in the first support member 4. Then, the ink flowing into the ink collection channel 49 flows into the circulation unit 54 through the collection port 89 in the connecting member 8 and is collected.

[0062] <Components of a Loop Unit>

[0063] Figure 4 This is a schematic external view of a circulation unit 54 for a type of ink used in the printing apparatus of this embodiment. A circulation pump 500 is mounted in the circulation unit 54. Furthermore, preferably, the circulation unit 54 includes a filter 110, a first pressure regulating unit 120, and a second pressure regulating unit 150. These components are connected via... Figure 5 and Figure 6 The channel connections shown form a circulation path for supplying ink to and collecting ink from the injection module 300 inside the liquid injection head 1.

[0064] <Circulation path in a liquid jet head>

[0065] Figure 5 This is a schematic vertical cross-sectional view illustrating the circulation path of one type of ink (one color of ink) formed in the liquid jet head 1. For a clearer depiction of the circulation path, simplifications have been made. Figure 5 The relative positions of the components (e.g., the first pressure regulating unit 120, the second pressure regulating unit 150, and the circulation pump 500) are also considered. Therefore, the relative positions of the components differ from those mentioned later. Figure 19 The relative positions of the components. Incidentally, Figure 6 It is shown schematically. Figure 5 The diagram shows a loop path. (As shown) Figure 5 and Figure 6As 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 achieve circulation within a specific pressure range in 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. Figure 5 and Figure 6 Describe the circulation path in liquid jet head 1 and the ink flow within that path. Note that... Figure 5 and Figure 6 The arrows in the diagram indicate the direction of ink flow.

[0066] First, we will describe how the components in the liquid jet head 1 are connected.

[0067] The ink can 2, which is located outside the liquid ejector head 1, is stored in the ink can. Figure 6 The ink in the liquid jet head 1 is supplied to an external pump 21, which is connected to a circulation unit 54 via an ink supply pipe 59 (Fig. 1). A filter 110 is installed in the ink channel (inflow channel) upstream of the circulation unit 54. The ink supply path (inflow channel) 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 accessible by a... Figure 5 The valve 190A shown has a connection port 191A that connects to the first pressure control chamber 122. Note that the inflow channel is a channel through which liquid in the ink tank 2, located outside the liquid ejector head 1, flows into the liquid ejector head 1 to be supplied to the pressure chamber 12. Specifically, the inflow channel is a flow channel through which the ink tank 2 and the liquid ejector head 1 are connected to each other, and liquid in the ink tank flows into the liquid ejector head. As will be described later, the inflow channel connects to an upstream channel in the liquid ejector head 1. Thus, liquid that has flowed into the upstream channel through the inflow channel and passed through the bypass channel 160 can be supplied to the pressure chamber 12 through the downstream channel.

[0068] The first pressure control chamber 122 is connected to the supply channel 130, bypass channel 160, and pump outlet channel 180 of the circulation pump 500. The supply channel 130 is connected to the common supply channel 18 via the ink supply port provided in the ink injection module 300. Furthermore, 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 via a... Figure 5 The valve 190B shown has a connection port 191B that connects to the second pressure control chamber 152 when it is open and closed. Note that... Figure 5 and Figure 6 An example is shown where one end of the bypass channel 160 is connected to the first pressure control chamber 122 of the first pressure regulating unit 120, and the other end of the bypass channel 160 is connected to the second valve chamber 151 of the second pressure regulating unit 150. However, the one end of the bypass channel 160 may be connected to the supply channel 130, and the other end of the bypass channel may be connected to the second valve chamber 151.

[0069] The second pressure control chamber 152 is connected to the collection channel 140. The collection channel 140 is connected to the common collection channel 19 via the ink collection port provided in the jet module 300. Furthermore, the second pressure control chamber 152 is connected to the circulation pump 500 via the pump inlet channel 170. Note that... Figure 5 In the attached figure, reference numeral 170a indicates the inlet of pump inlet channel 170.

[0070] Next, the ink flow in the liquid jet head 1 with the above-described structure will be described. For example... Figure 6 As shown, the ink stored in the ink tank 2 is pressurized by the external pump 21 in the liquid jet device 50, becoming a positive pressure ink flow, and is supplied to the circulation unit 54 of the liquid jet head 1.

[0071] Ink supplied to circulation unit 54 passes through filter 110, thereby removing foreign matter such as dust and air bubbles. The ink then flows into first valve chamber 121 located in first pressure regulating unit 120. As the ink passes through filter 110, the pressure on the ink decreases due to pressure loss, but the pressure on the ink remains positive. Subsequently, with valve 190A open, the ink flowing into first valve chamber 121 passes through connection port 191A and flows into first pressure control chamber 122. Due to the pressure loss as the ink passes through connection port 191A, the pressure on the ink flowing into first pressure control chamber 122 changes from positive to negative.

[0072] Next, the ink flow in the circulation path will be described. The circulation pump 500 operates such that ink drawn in from the pump inlet channel 170 located upstream of the circulation pump 500 is delivered to the pump outlet channel 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 channel 130 and the bypass channel 160 together with the ink delivered from the pump outlet channel 180. In this embodiment, although details will be described later, a piezoelectric diaphragm pump using a piezoelectric element attached to a diaphragm as a drive source is used as a circulation pump capable of delivering liquid. The piezoelectric diaphragm pump delivers liquid by inputting a drive voltage to the piezoelectric element to change the volume of the pump chamber and alternately moving two check valves in response to pressure changes.

[0073] Ink flowing into supply channel 130 flows from the ink supply port in the jet module 300 into pressure chamber 12 through common supply channel 18. When the jet element 15 is driven (generating heat), a portion of the ink is ejected from jet port 13. Furthermore, any unused ink during jetting flows through pressure chamber 12 and through common collection channel 19. Thereafter, the ink flows into collection channel 140 connected to jet module 300. The ink flowing into collection channel 140 flows into second pressure control chamber 152 of second pressure regulating unit 150.

[0074] On the other hand, ink flowing from the first pressure control chamber 122 into the bypass channel 160 flows into the second valve chamber 151, passes through the connecting port 191B, and then flows into the second pressure control chamber 152. When the circulation pump 500 is driven, ink flowing into the second pressure control chamber 152 through the bypass channel 160 and ink collected from the collection channel 140 are drawn into the circulation pump 500 through the pump inlet channel 170. Then, the ink drawn into the circulation pump 500 is sent to the pump outlet channel 180 and flows back into the first pressure control chamber 122. Thereafter, ink flowing from the first pressure control chamber 122 into the second pressure control chamber 152 through the supply channel 130 and the injection module 300, and ink flowing into the second pressure control chamber 152 through the bypass channel 160, flows into the circulation pump 500. Then, ink is sent from the circulation pump 500 to the first pressure control chamber 122. Ink circulates within the circulation path in this way.

[0075] Here, the passage through which the first part of the pressure chamber 12 and the circulation pump 500 are connected and through which liquid is supplied to the pressure chamber 12 will be referred to as the "upstream passage". Furthermore, the passage through which the second part of the pressure chamber 12 and the circulation pump 500 are connected and through which liquid is collected from the pressure chamber 12 will be referred to as the "downstream passage".

[0076] The upstream channel includes a first pressure regulating unit 120, a first channel (supply channel 130) through which the first pressure regulating unit 120 and a first portion of pressure chamber 12 communicate with each other, and a third channel (pump outlet channel 180) through which the circulation pump 500 and the first pressure regulating unit 120 communicate with each other. The downstream channel includes a second pressure regulating unit 150, a second channel (collection channel 140) through which the second portion of pressure chamber 12 and the second pressure regulating unit 150 communicate with each other, and a fourth channel (pump inlet channel 170) through which the second pressure regulating unit 150 and circulation pump 500 communicate with each other. In other words, circulation pump 500 allows liquid in the downstream channel to flow into the upstream channel. Note that the upstream channel only needs to allow circulation pump 500 and the first portion of pressure chamber 12 to communicate with each other, and the downstream channel only needs to allow the second portion of pressure chamber 12 and circulation pump 500 to communicate with each other.

[0077] Therefore, in this embodiment, the liquid flows sequentially through the circulation pump 500, the third channel 180, the first pressure regulating unit 120, the first channel 130, the pressure chamber 12, the second channel 140, the second pressure regulating unit 150, the fourth channel 170, and the circulation pump 500, which serve as circulation paths.

[0078] As described above, in this embodiment, the liquid can be circulated by the circulation pump 500 through various circulation paths formed in the liquid jet head 1. This allows for the suppression of ink thickening in the jet module 300 and the deposition of pigment components in the color material. Therefore, excellent ink flowability and excellent jetting characteristics at the jet nozzle can be maintained in the jet module 300.

[0079] Furthermore, in this embodiment, the circulation path is constructed to complete within the liquid ejector head 1. Therefore, the length of the circulation path is significantly shorter compared to the case where the ink circulates between the ink tank 2, which is located outside the liquid ejector head 1, and the liquid ejector head 1. Thus, the ink can be circulated using a small circulation pump.

[0080] Furthermore, this configuration only includes a channel for supplying ink, serving as a connection channel between the liquid jet head 1 and the ink tank 2. In other words, a configuration that eliminates the need for a channel to collect ink from the liquid jet head 1 into the ink tank 2 is adopted. Therefore, only an ink supply tube connecting the ink tank 2 and the liquid jet head 1 is required, and an ink collection tube is unnecessary. Consequently, the internal structure of the liquid jet device 50 is simpler, with fewer tubes. This reduces the overall size of the device. In addition, the reduction in the number of tubes reduces ink pressure fluctuations caused by tube oscillation due to the main scan of the liquid jet head 1. Furthermore, tube oscillation during the main scan of the liquid jet head 1 increases the drive load on the carriage motor of the drive carriage 60. Therefore, the reduction in the number of tubes reduces the drive load on the carriage motor, thereby simplifying the main scan mechanism, including the carriage motor and the like. Furthermore, since it is not necessary to collect ink from the liquid jet head 1 into the ink tank, the size of the external pump 21 can also be reduced. As described above, according to this embodiment, the size of the liquid jet device 50 can be reduced and the cost lowered.

[0081] <Pressure Regulation Unit>

[0082] Figures 7A to 7C This is a diagram showing an example of a pressure regulating unit. (Refer to...) Figures 7A to 7C The construction and operation of the pressure regulating units (first pressure regulating unit 120 and second pressure regulating unit 150) incorporated in the liquid injection head 1 described above 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 construction. Therefore, the following description will take the first pressure regulating unit 120 as an example. For the second pressure regulating unit 150, in Figures 7A to 7COnly the reference numerals for the parts corresponding to the first pressure regulating unit are shown in the figures. 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 understood as the second valve chamber 151 and the second pressure control chamber 152, respectively.

[0083] 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 disposed 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 disposed in the first valve chamber 121, which switches between allowing communication between the first valve chamber 121 and the first pressure control chamber 122 through the communication port 191 and blocking such communication. The valve 190 is held in a position opposite to the communication port 191 by a valve spring 200 and has a configuration of close contact with the partition 123 by a biasing force from the valve spring 200. The valve 190 prevents ink from flowing through the communication port 191 by its close contact with the partition 123. Note that the portion of valve 190 that contacts the separator 123 is preferably formed of an elastic member to enhance the tightness of the contact with the separator 123. Furthermore, the valve shaft 190a, which is to be inserted through the connection port 191, is positioned in a protruding manner on the central portion of valve 190. By pressing the valve shaft 190a against the biasing force from the valve spring 200, valve 190 separates from the separator 123, thereby allowing ink to flow through the connection port 191. In the following text, the state in which valve 190 blocks ink flow through the connection port 191 will be referred to as the "closed state," while the state in which ink can flow through the connection port 191 will be referred to as the "open state."

[0084] The opening of the cylindrical housing 125 is closed by a flexible member 230 and a pressure plate 210. These flexible members 230, pressure plate 210, the peripheral wall of the housing 125, and the partition 123 form a first pressure control chamber 122. The pressure plate 210 is configured to move with the displacement of the flexible member 230. While 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 of molded resin, 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 thermal welding.

[0085] A pressure adjusting spring 220 (biasing member) is disposed between the pressure plate 210 and the separator 123. For example... Figure 7AAs shown, the pressure plate 210 and flexible member 230 are biased by the biasing force from the pressure regulating spring 220 in the direction of increasing internal volume of the first pressure control chamber 122. Furthermore, as the pressure in the first pressure control chamber 122 decreases, the pressure plate 210 and flexible member 230 displace against the pressure from the pressure regulating spring 220 in the direction of decreasing internal volume of the first pressure control chamber 122. Then, when 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, together with the valve shaft 190a, moves against the biasing force from the valve spring 200, thereby separating from the separator 123. As a result, the communication port 191 changes to the open state. Figure 7B (State).

[0086] In this embodiment, the connection in the circulation path is configured such that when the connection port 191 is switched to the open state, the pressure in the first valve chamber 121 is higher than the pressure in the first pressure control chamber 122. Thus, when the connection port 191 is switched to the open state, ink flows from the first valve chamber 121 into the first pressure control chamber 122. The inflow of ink causes the flexible member 230 and the pressure plate 210 to shift in the direction of increasing internal volume of the first pressure control chamber 122. As a result, the pressure plate 210 separates from the valve shaft 190a of the valve 190, and the valve 190 comes into close contact with the separator 123 by the biasing force from the valve spring 200, causing the connection port 191 to switch to the closed state. Figure 7C (State).

[0087] As described above, in the first pressure regulating unit 120 of this embodiment, when the pressure in the first pressure control chamber 122 decreases to a specific pressure or lower (e.g., when the negative pressure increases), ink flows from the first valve chamber 121 through the communication port 191. This configuration limits further pressure reduction in the first pressure control chamber 122. Therefore, the pressure in the first pressure control chamber 122 is controlled to remain within a certain range.

[0088] Next, the pressure in the first pressure control chamber 122 will be described in more detail. Consider a state in which, as described above, the flexible member 230 and the pressure plate 210 are displaced according to the pressure in the first pressure control chamber 122, such that the pressure plate 210 abuts against the valve shaft 190a and opens the communication port 191. Figure 7B (The state of the pressure plate 210). At this time, the relationship between the forces acting on the pressure plate 210 is represented by the following equation 1.

[0089] P2×S2+F2+(P1-P2)×S1+F1=0…Equation 1

[0090] Furthermore, for P2, Equation 1 can be summarized as follows.

[0091] P2=-(F1+F2+P1×S1) / (S2-S1)…Equation 2

[0092] P1: Pressure (gauge pressure) in the first valve chamber 121

[0093] P2: Pressure (gauge pressure) in the first pressure control chamber 122

[0094] F1: Spring force of valve spring 200

[0095] F2: Spring force of pressure regulating spring 220

[0096] S1: Pressure receiving area of ​​valve 190

[0097] S2: Pressure receiving area of ​​pressure plate 210

[0098] Here, the spring force F1 of valve spring 200 and the spring force F2 of pressure regulating spring 220 are defined as the positive direction in which they push valve 190 and pressure plate 210. Figures 7A to 7C (to the left in the middle). In addition, this structure ensures 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.

[0099] When the connection port 191 is switched to the open state, the pressure P2 in the first pressure control chamber 122 is determined by Equation 2. Since the structure satisfies the relationship P1 ≥ P2, ink flows from the first valve chamber 121 into the first pressure control chamber 122 when the connection port 191 is switched to the open state. As a result, the pressure P2 in the first pressure control chamber 122 does not decrease further and remains within a certain range.

[0100] On the other hand, such as Figure 7C As shown, when the pressure plate 210 is not 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 expressed by the following equation 3.

[0101] P3×S3+F3=0…Equation 3

[0102] Here, Equation 3 for P3 is summarized as follows.

[0103] P3 = -F3 / S3…Equation 4

[0104] F3: The spring force of the pressure regulating spring 220 when the pressure plate 210 is not against the valve shaft 190a.

[0105] P3: Pressure (gauge pressure) in the first pressure control chamber 122 when the pressure plate 210 is not against the valve shaft 190a.

[0106] S3: Pressure receiving area of ​​pressure plate 210 when pressure plate 210 is not against valve shaft 190a

[0107] Here, Figure 7C The pressure plate 210 and the flexible member 230 are shown in Figure 7C 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 are adjusted according to the pressure plate 210 and the flexible component 230. Figure 7C The state changes with the amount of displacement. Specifically, in the pressure plate 210 and the flexible member 230... Figure 7C In relation to themselves, they are located in Figure 7C In the case on the right side, the pressure receiving area S3 of the pressure plate 210 is smaller, and the spring force F3 of the pressure adjusting spring 220 is larger. Therefore, according to the relationship in Equation 4, the pressure P3 in the first pressure control chamber 122 is smaller. Therefore, using Equations 2 and 4, when from... Figure 7B State transition to Figure 7C When the pressure plate 210 and flexible member 230 are in the open state of the communication port 191, the pressure in the first pressure control chamber 122 gradually increases (i.e., the negative pressure weakens towards the value of the positive pressure side). Specifically, when the pressure plate 210 and flexible member 230 gradually shift to the left from the open state of the communication port 191 until the internal volume of the first pressure control chamber reaches the limit of the displacement of the pressure plate 210 and flexible member 230, the pressure in the first pressure control chamber 122 gradually increases. In other words, the negative pressure weakens. In this embodiment, the first pressure regulating unit 120 regulates the pressure in the upstream channel, and the second pressure regulating unit 150 regulates the pressure in the downstream channel. Specifically, the first pressure regulating unit 120 regulates the pressure in the first channel (supply channel 130), and the second pressure regulating unit 150 regulates the pressure in the second channel (collection channel 140).

[0108] <Circulation Pump>

[0109] Next, we will refer to Figure 8A , 8B and Figure 9 The construction and operation of each circulation pump 500 included in the liquid injection head 1 described above are described in detail.

[0110] Figure 8A and 8B This is an external perspective view of the circulating pump 500. Figure 8A This is an external perspective view showing the front side of the circulating pump 500. Figure 8BThis is an external perspective view showing the rear 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 body 505a and a channel connecting member 505b adhesively fixed to the outer surface of the housing body 505a. In each of the housing body 505a and the channel connecting member 505b, a pair of through holes communicating with each other are formed at two different locations. One of the through holes in the pair, located at one location, forms a pump supply hole 501. The other through hole in the pair, located at the other location, forms a pump discharge hole 502. The pump supply hole 501 is connected to a pump inlet channel 170, which is connected to a second pressure control chamber 152. The pump discharge hole 502 is connected to a pump outlet channel 180, which is connected to a first pressure control chamber 122. Ink supplied from the pump supply hole 501 passes through a pump chamber 503 (described later) Figure 9 And it is discharged from the pump discharge port 502.

[0111] Figure 9 yes Figure 8A The diagram shows a cross-sectional view of the circulating pump 500 along line IX-IX. A diaphragm 506 is joined to the inner surface of the pump housing 505, and a pump chamber 503 is formed between the diaphragm 506 and a recess formed in the inner surface of the pump housing 505. The pump chamber 503 communicates with a pump supply port 501 and a pump discharge port 502 formed in the pump housing 505. Furthermore, a check valve 504a is disposed in the middle portion of the pump supply port 501. A check valve 504b is disposed in the middle portion of the pump discharge port 502. That is, the circulating pump 500 includes check valves in the channels that connect the downstream and upstream channels to each other. These check valves prevent liquid in the upstream channel from flowing into the downstream channel through the circulating pump 500. Note that in this embodiment, the check valves are included in the channels in the circulating pump 500 through which the fourth channel 170 and the third channel 180 communicate with each other. Specifically, the check valve 504a is configured such that a portion thereof is contained within the space 512a formed in the middle portion of the pump supply port 501. Figure 9 It moves to the left. The check valve 504b is configured such that a portion of it can move within the space 512b formed in the middle portion of the pump discharge port 502. Figure 9 Move to the right.

[0112] As the diaphragm 506 shifts to increase the volume of the pump chamber 503, the pump chamber 503 is depressurized. In response to this shift, the check valve 504a separates from the opening of the pump supply port 501 in the space 512a (i.e., in...). Figure 9(Moving to the left). By separating from the opening of the pump supply port 501 in space 512a, the check valve 504a switches to an open state that allows ink to flow through the pump supply port 501. The pump chamber 503 is pressurized when the diaphragm 506 shifts to reduce the volume of the pump chamber 503. In response to this shift, the check valve 504a comes into close contact with the wall surface surrounding the opening of the pump supply port 501. The check valve 504a is thus in a closed state, in which it blocks ink from flowing through the pump supply port 501.

[0113] On the other hand, when the pump chamber 503 is depressurized, the check valve 504b comes into close contact with the wall surrounding the opening in the pump housing 505, thereby switching to a closed state. In this state, the check valve 504b prevents ink from flowing through the pump discharge port 502. Furthermore, when the pump chamber 503 is pressurized, the check valve 504b separates from the opening in the pump housing 505 and moves toward the space 512b (i.e., in...). Figure 9 (Move to the right from center), thereby allowing ink to flow through pump discharge hole 502.

[0114] Note that the material of each check valve 504a and 504b only needs to be a material that can deform under the pressure in the pump chamber 503. For example, the material of each check valve 504a and 504b can be made of an elastic material, such as ethylene propylene diene monomer (EPDM) rubber or an elastomer, or a membrane or sheet of polypropylene, etc. However, the material is not limited to these.

[0115] As described above, the pump chamber 503 is formed by joining the pump housing 505 and the diaphragm 506. Therefore, the pressure in the pump chamber 503 changes as the diaphragm 506 deforms. For example, when the diaphragm 506 shifts toward the pump housing 505 (towards...) Figure 9 When the volume of pump chamber 503 is reduced due to the rightward shift of the pump valve 504, the pressure in pump chamber 503 increases. As a result, check valve 504b, which is positioned facing pump discharge port 502, switches to the open state, allowing ink to be discharged from pump chamber 503. At this time, check valve 504a, which is positioned facing pump supply port 501, comes into close contact with the wall surrounding pump supply port 501, thereby preventing ink from flowing back from pump chamber 503 into pump supply port 501.

[0116] Conversely, when the diaphragm 506 shifts in the direction that widens the pump chamber 503, the pressure in the pump chamber 503 decreases. As a result, the check valve 504a, positioned facing the pump supply port 501, switches to the open state, allowing ink to be supplied to the pump chamber 503. At this time, the check valve 504b, located in the pump discharge port 502, comes into close contact with the wall surrounding the opening formed in the pump housing 505, closing the opening. This prevents ink from flowing back from the pump discharge port 502 into the pump chamber 503.

[0117] As described above, in the circulating pump 500, ink is drawn in and discharged as the diaphragm 506 deforms, thereby changing the pressure in the pump chamber 503. At this time, if air bubbles have already entered the pump chamber 503, the displacement of the diaphragm 506 slightly alters the pressure in the pump chamber 503 due to the expansion or contraction of the bubbles. Therefore, the amount of liquid to be pumped decreases. To address this phenomenon, the pump chamber 503 is arranged parallel to gravity, allowing air bubbles that have entered the pump chamber 503 to easily accumulate at the top. Furthermore, the pump discharge port 502 is positioned above the center of the pump chamber 503. This improves the ease with which air bubbles are discharged from the pump, thereby stabilizing the flow rate.

[0118] <Ink flow within the liquid jet head>

[0119] Figures 10A to 10E This is a diagram depicting the ink flow inside a liquid ejector head. (Refer to...) Figures 10A to 10E This describes the ink circulation process that occurs inside the liquid ejector head 1. To more clearly illustrate the ink circulation path, a simplified version is provided. Figures 10A to 10E The relative positions of the components (e.g., the first pressure regulating unit 120, the second pressure regulating unit 150, and the circulation pump 500) are also considered. Therefore, the relative positions of the components differ from those mentioned later. Figure 19 The relative positions of the components. Figure 10A This schematically illustrates the ink flow during a printing operation performed by ejecting ink from nozzle 13. Note that... Figure 10A The arrows in the diagram indicate ink flow. In this embodiment, both the external pump 21 and the circulation pump 500 are started to operate in order to perform a printing operation. Incidentally, the external pump 21 and the circulation pump 500 can be operated regardless of whether a printing operation is to be performed. The external pump 21 and the circulation pump 500 do not need to be driven together, but can be driven independently of each other.

[0120] During the printing operation, the circulation pump 500 is in the on (driven) state, causing ink flowing from the first pressure control chamber 122 to flow into the supply channel 130 and the bypass channel 160. The ink that has flowed into the supply channel 130 passes through the jetting module 300 and then flows into the collection channel 140. Thereafter, the ink is supplied to the second pressure control chamber 152.

[0121] On the other hand, ink flowing from the first pressure control chamber 122 into the bypass channel 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 passes through the pump inlet channel 170, the circulation pump 500, and the pump outlet channel 180, and then flows back into the first pressure control chamber 122. At this time, based on the relationship in Equation 2 above, the controlled pressure in the first valve chamber 121 is set higher than the controlled pressure in the first pressure control chamber 122. Therefore, the ink in the first pressure control chamber 122 does not flow into the first valve chamber 121, but is instead supplied back to the injection module 300 through the supply channel 130. The ink flowing into the injection module 300 flows back into the first pressure control chamber 122 through the collection channel 140, the second pressure control chamber 152, the pump inlet channel 170, the circulation pump 500, and the pump outlet channel 180. Ink circulation completed within the liquid injection head 1 is performed as described above.

[0122] In the aforementioned 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 ink circulation volume (flow rate) within the ejection module 300. Furthermore, this pressure difference is set to obtain a circulation volume capable of suppressing ink thickening near the ejection nozzle in the ejection module 300. Incidentally, the ink consumed by printing is supplied from the ink tank 2 through the filter 110 and the first valve chamber 121 to the first pressure control chamber 122. How the consumed ink is supplied will now be described in detail. The ink in the circulation path reduces the amount of ink consumed by printing. Therefore, the pressure in the first pressure control chamber 122 decreases, resulting in a reduction in the ink in the first pressure control chamber. As the ink in the first pressure control chamber 122 decreases, the internal volume of the first pressure control chamber 122 decreases accordingly. As this internal volume of the first pressure control chamber 122 decreases, the connection port 191A switches to the open state, allowing ink to be supplied from the first valve chamber 121 to the first pressure control chamber 122. When ink supplied from the first valve chamber 121 passes through the connection port 191A, a pressure loss occurs in the supplied ink. As the ink flows into the first pressure control chamber 122, the positive pressure on the ink changes to a negative pressure. As 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 connection port 191A switches to a closed state. As described above, the connection port 191A repeatedly switches between an open and closed state according to ink consumption. Incidentally, when no ink is consumed, the connection port 191A remains in the closed state.

[0123] Figure 10BThe diagram schematically illustrates the ink flow immediately after the printing operation is completed and the circulation pump 500 is switched to the off state (stopped state). When the printing operation is completed and the circulation pump 500 is switched to the off state, the pressure in the first pressure control chamber 122 and the pressure in the second pressure control chamber 152 are both controlled pressures used in the printing operation. Therefore, based on the pressure difference between the pressure in the first pressure control chamber 122 and the pressure in the second pressure control chamber 152, the ink... Figure 10B The movement is as shown. Specifically, ink flow continues to be generated from the first pressure control chamber 122 through the supply channel 130 to the jet module 300 and then through the collection channel 140 to the second pressure control chamber 152. In addition, ink flow continues to be generated from the first pressure control chamber 122 through the bypass channel 160 and the second valve chamber 151 to the second pressure control chamber 152.

[0124] The amount of ink that moves from the first pressure control chamber 122 to the second pressure control chamber 152 via these ink flows is supplied from the ink tank 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 remains constant. According to the relationship in Equation 2 above, when the internal volume of the first pressure control chamber 122 is constant, the spring force F1 of the valve spring 200, the spring force F2 of the pressure regulating spring 220, the pressure receiving area S1 of the valve 190, and the pressure receiving area S2 of the pressure plate 210 remain constant. Therefore, the pressure in the first pressure control chamber 122 depends on the change in the pressure (gauge pressure) P1 in the first valve chamber 121. Thus, when the pressure P1 in the first valve chamber 121 remains constant, the pressure P2 in the first pressure control chamber 122 is maintained at the same pressure as the controlled pressure during printing operation.

[0125] On the other hand, the pressure in the second pressure control chamber 152 changes over time according to the change in internal volume caused by the ink inflow from the first pressure control chamber 122. Specifically, the pressure in the second pressure control chamber 152 changes according to Equation 2 until the connecting port 191... Figure 10B The state changes to the closed state to prevent communication between the second valve chamber 151 and the second pressure control chamber 152, such as... Figure 10C As shown. Afterwards, the pressure plate 210 no longer abuts against the valve shaft 190a, causing the connection port 191 to switch to the closed state. Then, as... Figure 10D As shown, ink flows from collection channel 140 into the second pressure control chamber 152. The inflow of ink causes displacement of pressure plate 210 and flexible member 230. The pressure in the second pressure control chamber 152 varies according to Equation 4. Specifically, the pressure increases until the internal volume of the second pressure control chamber 152 reaches its maximum value.

[0126] Note that once it reaches... Figure 10CIn this state, ink no longer flows from the first pressure control chamber 122 into the second pressure control chamber 152 through the bypass channel 160 and the second valve chamber 151. Therefore, ink flow to the second pressure control chamber 152 through the collection channel 140 only occurs after ink in the first pressure control chamber 122 is supplied to the jet module 300 through the supply channel 130. As described above, ink moves from the first pressure control chamber 122 to the second pressure control chamber 152 based on 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.

[0127] 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... Figure 10D The state shown. In the second pressure control chamber 152, as indicated. Figure 10D Under the expansion shown, a storage section 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... Figure 10D The process takes approximately 1 to 2 minutes. This time can vary depending on the shape and size of the channel and the properties of the ink. Figure 10D As shown, when the circulation pump 500 is driven while the ink is held in the storage section, the ink in the storage section is supplied to the first pressure control chamber 122 via the circulation pump 500. Therefore, as Figure 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 in the expansion direction. Then, as the circulation pump 500 continues to be driven, the state inside the circulation path changes to... Figure 10A The state shown.

[0128] Note that in the above description, Figure 10A This has been described as an example of ink circulation during a printing operation. However, as mentioned above, ink can circulate even without a printing operation. Even in this case, ink circulates in response to the driving and stopping of the circulation pump 500. Figures 10A to 10E The flow is shown.

[0129] Furthermore, as described above, this embodiment uses 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 the driving 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 the driving circulation pump 500. This will be described in detail below along with the function of the bypass channel 160.

[0130] The bypass channel 160 is provided between the first pressure regulating unit 120 and the second pressure regulating unit 150 to prevent the jet module 300 from being affected by strong negative pressure, for example, if the negative pressure generated in the circulation path becomes stronger than a preset value. The bypass channel 160 is also provided to supply ink to the pressure chamber 12 from the supply channel 130 and the collection channel 140.

[0131] First, an example will be explained to prevent the negative pressure from becoming stronger than the preset value on the jet module 300 by setting the bypass channel 160. For example, changes in ambient temperature can sometimes alter the properties of the ink (e.g., viscosity). As the ink viscosity changes, the pressure loss within the circulation path also changes. For example, as the ink viscosity decreases, the amount of pressure loss within the circulation path decreases. As a result, the flow rate of the circulation pump 500, driven at a constant drive, increases, and the flow rate through the jet module 300 increases. Here, the jet module 300 is maintained at a constant temperature by a temperature regulating mechanism (not shown). Therefore, even if the ambient temperature changes, the viscosity of the ink inside the jet module 300 remains constant. Since the viscosity of the ink inside the jet module 300 remains constant, while the flow rate of the ink flowing through the jet module 300 increases, the negative pressure in the jet module 300 correspondingly increases due to flow resistance. If, as described above, the negative pressure in the jet module 300 becomes stronger than the preset value, there is a possibility that the meniscus in the jet nozzle 13 may rupture and ambient air may be drawn into the circulation path, which could lead to the inability to perform normal jetting. Furthermore, even if the meniscus does not rupture, the negative pressure in pressure chamber 12 may still become stronger than the predetermined level and affect the jetting.

[0132] For these reasons, in this embodiment, a bypass channel 160 is formed in the circulation path. By providing the bypass channel 160, ink flows through the bypass channel 160 when the negative pressure is stronger than a preset value. Therefore, the pressure in the ejection module 300 remains constant. Thus, for example, the controlled pressure can be set such that the connection port 191B in the second pressure regulating unit 150 remains closed even when the circulation pump 500 is driven. Furthermore, the controlled pressure in the second pressure regulating unit 150 can be set such that the connection port 191B in the second pressure regulating unit 150 switches to the open state when the negative pressure becomes stronger than a preset value. In other words, when the circulation pump 500 is driven, as long as the meniscus does not collapse or the predetermined negative pressure is maintained, the connection port 191B can remain closed even if the pump flow rate changes due to viscosity changes caused by environmental changes, etc.

[0133] Next, an example of setting up a bypass channel 160 to supply ink from the supply channel 130 and the collection channel 140 to the pressure chamber 12 will be described. The pressure in the circulation path may fluctuate due to the ejection operation of the ejection element 15. This is because the ejection operation generates a force that draws ink into the pressure chamber.

[0134] In the following text, it will be stated that during continuous high-load printing, the ink to be supplied to pressure chamber 12 is supplied from both the supply channel 130 side and the collection channel 140 side. While the definition of "load" may vary depending on various conditions, in the following text, the state of printing a grid cell at 1200 dots per inch (dpi) with a single 4-picoliter (pl) ink droplet will be considered 100%. "High-load printing" is, for example, printing performed at 100% load.

[0135] Under continuous high-load printing, the amount of ink flowing from pressure chamber 12 into second pressure control chamber 152 through collection channel 140 decreases. On the other hand, circulation pump 500 causes ink to flow out at a constant rate. This disrupts the balance between inflow and outflow in second pressure control chamber 152. Consequently, the amount of ink in second pressure control chamber 152 decreases, and the negative pressure in second pressure control chamber 152 strengthens, causing second pressure control chamber 152 to contract. As the negative pressure in second pressure control chamber 152 strengthens, the amount of ink flowing into second pressure control chamber 152 through bypass channel 160 increases, and second pressure control chamber 152 stabilizes in a state of balance between inflow and outflow. Therefore, the negative pressure in second pressure control chamber 152 strengthens according to the load. Furthermore, as described above, in a configuration where connection port 191B is closed when circulation pump 500 is driven, connection port 191B switches to an open state according to the load, causing ink to flow into second pressure control chamber 152 from bypass channel 160.

[0136] Furthermore, as high-volume printing continues, the amount of ink flowing from pressure chamber 12 into the second pressure control chamber 152 through collection channel 140 decreases, while the amount flowing from connector 191B into the second pressure control chamber 152 through bypass channel 160 increases. As this state progresses further, the amount of ink flowing from pressure chamber 12 into the second pressure control chamber 152 through collection channel 140 reaches zero, such that the ink flowing out of connector 191B is all the ink that has flowed out of circulation pump 500. As this state progresses further, ink flows back from the second pressure control chamber 152 into pressure chamber 12 through collection channel 140. In this state, the ink flowing from the second pressure control chamber 152 into circulation pump 500 and from the second pressure control chamber 152 into pressure chamber 12 will flow into the second pressure control chamber 152 through bypass channel 160 from connector 191B. In this case, ink from supply channel 130 and ink from collection channel 140 are filled into pressure chamber 12 and ejected from pressure chamber 12.

[0137] Please note that the ink backflow that occurs under high print load is due to the installation of the bypass channel 160. Furthermore, as described above, an example of switching the connection port 191B in the second pressure regulating unit to the open state for ink backflow has been presented. However, ink backflow may also occur even when the connection port 191B in the second pressure regulating unit is open. Moreover, in a configuration without a second pressure regulating unit, the aforementioned ink backflow can also occur by installing the bypass channel 160.

[0138] <Construction of the jet unit>

[0139] Figure 11A and 11B The diagram illustrates the circulation path of one color ink in the spraying unit 3 of this embodiment. Figure 11A This is an exploded perspective view of the injection unit 3 as seen from the side of the first support member 4. Figure 11B This is an exploded perspective view of the injection unit 3 as seen from the side of the injection module 300. Note that... Figure 11A and 11B The arrows labeled "in" and "out" indicate ink flow, and the description will only apply to one color; however, other colors of ink flow similarly. Furthermore, in Figure 11A and 11B The illustrations of the second support member 7 and the electrical wiring member 5 are omitted, and their descriptions are also omitted in the following description of the construction of the injection unit. Furthermore, for Figure 11A The first support member 4 in the middle shows along Figure 3A The cross-section of line XI-XI in the middle. Each spray module 300 includes a spray element substrate 340 and an opening plate 330. Figure 12 This is a view showing the opening plate 330. Figure 13 This is a view showing the jetting element substrate 340.

[0140] Ink is supplied from each circulation unit 54 to the jetting unit 3 via the connecting member 8 (see...) Figure 3A The ink path returning to the joining member 8 after passing through it will now be described. Note that the illustration of the joining member 8 is omitted in the figures to be mentioned below.

[0141] Each ejection module 300 includes an ejection element substrate 340 as a silicon substrate 310 and an aperture plate 330, and also includes an outlet forming member 320. The ejection element substrate 340, aperture plate 330, and outlet forming member 320 are stacked and joined to form the ejection module 300, such that the channels of each ink are in communication with each other. The ejection module 300 is supported on a first support member 4. The ejection unit 3 is formed by supporting each ejection module 300 on the first support member 4. The ejection element substrate 340 includes the outlet forming member 320, and the outlet forming member 320 includes a plurality of ejection port arrays, each ejection port array being a plurality of ejection ports 13 forming a row. A portion of the ink supplied through the ink channels in the ejection module 300 is ejected from the ejection ports 13. Unejected ink is collected through the ink channels in the ejection module 300.

[0142] like Figure 11A and 11B as well as Figure 12 As shown, the opening plate 330 includes a plurality of arranged ink supply ports 311 and a plurality of arranged ink collection ports 312. For example... Figure 13 and Figures 14A to 14C As shown, the jetting element substrate 340 includes a plurality of arranged supply connection channels 323 and a plurality of arranged collection connection channels 324. The jetting element substrate 340 also includes a common supply channel 18 communicating with the plurality of supply connection channels 323 and a common collection channel 19 communicating with the plurality of collection connection channels 324. The ink supply channel 48 and ink collection channel 49 (see...) are provided in the first support member 4. Figure 3A and 3B The channels provided in each jet module 300 are interconnected to form ink channels inside the jet unit 3. The support member supply port 211 is an opening in the cross-section forming the ink supply channel 48. The support member collection port 212 is an opening in the cross-section forming the ink collection channel 49.

[0143] The ink to be supplied to the jetting unit 3 is from the circulation unit 54 (see...) Figure 3A The ink supply channel 48 (see) is supplied from the side to the first support member 4. Figure 3A Ink flowing through the support member supply port 211 in the ink supply channel 48 passes through the ink supply channel 48 (see ink supply channel 48). Figure 3A The ink supply port 311 in the opening plate 330 is supplied to the common supply channel 18 in the jet element substrate 340 and enters the supply connection channel 323. The channel up to this point is the supply-side channel. Thereafter, the ink passes through the pressure chamber 12 in the discharge port forming member 320 (see...). Figure 3B The ink flows into the collection connection channel 324 of the collection side channel. Details of the ink flow in the pressure chamber 12 will be described below.

[0144] In the collection side channel, ink entering the collection connection channel 324 flows into the common collection channel 19. Thereafter, ink flows from the common collection channel 19 through the ink collection port 312 in the opening plate 330 into the ink collection channel 49 in the first support member 4, and is collected into the circulation unit 54 through the support member collection port 212.

[0145] The areas on the opening plate 330 where neither the ink supply port 311 nor the ink collection port 312 exists correspond to the areas on the first support member 4 used to separate the support member supply port 211 and the support member collection port 212. Furthermore, the first support member 4 has no openings in these areas. When the inkjet module 300 and the first support member 4 are combined, these areas serve as the joining area.

[0146] exist Figure 12 In this configuration, multiple arrays of openings arranged along the X-direction are arranged side-by-side in the opening plate 330 along the Y-direction. Supply openings (IN) and collection openings (OUT) are arranged alternately in the Y-direction, while being offset from each other by half a pitch in the X-direction. Figure 13 In the jetting element substrate 340, a common supply channel 18 communicating with a plurality of supply connection channels 323 arranged in the Y direction and a common collection channel 19 communicating with a plurality of collection connection channels 324 arranged in the Y direction are alternately arranged in the X direction. The common supply channel 18 and the common collection channel 19 are separated by ink type. Furthermore, the number of jetting nozzle arrays for each color determines the number of common supply channels 18 and common collection channels 19 to be provided. Additionally, the number of supply connection channels 323 and the number of collection connection channels 324 provided correspond to the number of jetting nozzles 13. Note that a one-to-one correspondence is not required, and a single supply connection channel 323 and a single collection connection channel 324 can correspond to multiple jetting nozzles 13.

[0147] Each jetting module 300 is formed by stacking and joining the aforementioned opening plate 330 and jetting element substrate 340 so that the channels of each ink are connected to each other, and is supported on the first support member 4. As a result, an ink channel including the supply channel and collection channel as described above is formed.

[0148] Figures 14A to 14C This is a cross-sectional view showing the ink flow at different parts of the jetting unit 3. Figure 14A It is along Figure 11A The image shows a cross-section taken from line XIVA-XIVA, and also shows a cross-section of a portion of the ink supply unit 3, in which the ink supply channel 48 and the ink supply port 311 are connected to each other. Figure 14B It is along Figure 11A The image shows a cross-section taken along line XIVB-XIVB, and also shows a cross-section of a portion of the ink collection unit 3, in which the ink collection channel 49 and the ink collection port 312 are connected to each other. Furthermore, Figure 14CIt is along Figure 11A The cross-section is taken by line XIVC-XIVC, and shows the cross-section of the part of the ink supply port 311 and the ink collection port 312 that are not connected to the channel in the first support member 4.

[0149] like Figure 14A As shown, the ink supply channel supplies ink from the portion where the ink supply channel 48 in the first support member 4 and the ink supply port 311 in the opening plate 330 overlap and communicate with each other. Furthermore, as... Figure 14B As shown, the ink collection channel collects ink from the overlapping and connected portions of the ink collection channel 49 in the first support member 4 and the ink collection port 312 in the opening plate 330. Furthermore, as... Figure 14C As shown, the spraying unit 3 partially has areas where no openings are provided in the opening plate 330. In these areas, ink is neither supplied nor collected between the spraying element substrate 340 and the first support member 4. Figure 14A As shown, ink is supplied to the area where the ink supply port 311 is located. (As indicated...) Figure 14B As shown, ink is collected in the area where the ink collection port 312 is provided. Note that this embodiment has been described as an example using a configuration with an opening plate 330, but a configuration without the opening plate 330 can be used. For example, a configuration can be used 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 jetting element substrate 340 is bonded to the first support member 4.

[0150] Figure 15A and 15B This is a cross-sectional view showing the vicinity of the injection port 13 in the injection module 300. Figure 16A and 16B This is a cross-sectional view showing an injection module with a configuration as a comparative example, wherein the common supply channel 18 and the common collection channel 19 widen in the X direction. Note that... Figure 15A and 15B as well as Figure 16A and 16B The thick arrows shown in the common supply channel 18 and common collection channel 19 indicate the oscillating motion of ink that occurs in the configuration using the tandem liquid jetting device 50. When the jetting element 15 is driven, ink supplied to the pressure chamber 12 through the common supply channel 18 and the supply connection channel 323 is ejected from the jet nozzle 13. When the jetting element 15 is not driven, ink is collected from the pressure chamber 12 into the common collection channel 19 through the collection connection channel 324, which serves as the collection channel.

[0151] When using the tandem liquid jetting device 50 to jet the ink circulating as described above, the ink jetting is significantly affected by the oscillating motion of the ink within the ink channel caused by the main scanning of the liquid jetting head 1. Specifically, the effect of the oscillating motion of the ink within the ink channel manifests as differences in the amount of ink jetted and deviations in the jetting direction. For example... Figure 16A and 16B As shown, when the common supply channel 18 and common collection channel 19 have a wider cross-sectional shape in the X direction, which is the main scanning direction, the ink within the common supply channel 18 and common collection channel 19 is more susceptible to inertial forces in the main scanning direction, causing significant ink oscillation. This oscillating motion of the ink may affect the ink ejection from the ejection nozzle 13. Furthermore, widening the common supply channel 18 and common collection channel 19 in the X direction increases the distance between colors. This may reduce printing efficiency.

[0152] Therefore, in this embodiment, each public supply channel 18 and each public collection channel 19 (the cross-section of which is shown below) Figure 15A and 15B The configuration shown is as follows: each common supply channel 18 and each common collection channel 19 extends along the Y direction and also along the Z direction, with the Z direction perpendicular to the X direction, which is the main scanning direction. Using this configuration, the common supply channel 18 and the common collection channel 19 have a small channel width in the main scanning direction. By making the common supply channel 18 and the common collection channel 19 have a small channel width in the main scanning direction, during the main scan, the inertial force acting on the ink and applied in the direction opposite to the main scanning direction (…) Figure 15A and 15B The oscillating motion of ink within the common supply channel 18 and common collection channel 19 (as indicated by the thick black arrow in the image) becomes smaller. This reduces the impact of ink oscillation during ink ejection. Furthermore, by extending the common supply channel 18 and common collection channel 19 in the Z direction, their cross-sectional area is increased. This reduces the channel pressure drop.

[0153] As described above, each common supply channel 18 and each common collection channel 19 is given a small channel width in the main scanning direction. This configuration reduces the oscillating motion of ink within the common supply channel 18 and common collection channel 19 during the main scan, but does not eliminate the oscillating motion. Therefore, in this embodiment, in order to reduce the jetting differences between ink types that may be caused by the reduced oscillating motion, the configuration is such that the common supply channel 18 and common collection channel 19 are positioned to overlap each other in the X direction.

[0154] As described above, in this embodiment, the supply connection channel 323 and the collection connection channel 324 are configured to correspond to the ejection port 13. Furthermore, the correspondence between the supply connection channel 323 and the collection connection channel 324 is established such that the supply connection channel 323 and the collection connection channel 324 are arranged in the X direction, with the ejection port 13 inserted between them. Therefore, if the common supply channel 18 and the common collection channel 19 have portions that do not overlap with each other in the X direction, the correspondence between the supply connection channel 323 and the collection connection channel 324 in the X direction is disrupted. This mismatch affects the flow of ink in the pressure chamber 12 in the X direction and ink ejection. If this mismatch is combined with the effect of the oscillating motion of the ink, it may further affect the ink ejection from each ejection port.

[0155] Therefore, by arranging the common supply channel 18 and the common collection channel 19 in a position that overlaps with each other along the X-direction, the oscillating motion of the ink within the common supply channel 18 and the common collection channel 19 during the main scan is substantially the same at any position of the ejector nozzle 13 in the Y-direction. Consequently, the pressure difference generated in the pressure chamber 12 between the common supply channel 18 side and the common collection channel 19 side does not change significantly. These low pressure differences enable stable ejection.

[0156] Furthermore, some liquid jet heads in which ink circulates are configured such that the channel for supplying ink to the liquid jet head and the channel for collecting ink are the same channel. However, in this embodiment, the common supply channel 18 and the common collection channel 19 are different channels. Additionally, the supply connection channel 323 and the pressure chamber 12 are in communication with each other, the pressure chamber 12 and the collection connection channel 324 are in communication with each other, and ink is ejected from the ejection port 13 in the pressure chamber 12. That is, the following configuration is formed: the pressure chamber 12, which serves as the path connecting the supply connection channel 323 and the collection connection channel 324, includes the ejection port 13. Therefore, in each pressure chamber 12, an ink flow is generated from the supply connection channel 323 side to the collection connection channel 324 side, and the ink within the pressure chamber 12 is effectively circulated. The ink within the pressure chamber 12 is susceptible to evaporation from the ejection port 13, and is kept fresh by effectively circulating the ink within the pressure chamber 12.

[0157] Furthermore, since both channels (i.e., common supply channel 18 and common collection channel 19) are connected to the pressure chamber 12, ink can be supplied from both channels when high-flow-rate injection is required. In other words, compared to a configuration in which only a single channel is formed for ink supply and collection, the configuration in this embodiment has the advantage of not only performing efficient cycles but also handling high-flow-rate injection.

[0158] Incidentally, when the common supply channel 18 and the common collection channel 19 are positioned close to each other along the X direction, the impact of ink oscillation is minimal. The common supply channel 18 and the common collection channel 19 are ideally positioned such that the gap between the channels is 75 to 100 micrometers.

[0159] Figure 17 This is a view showing the jetting element substrate 340 as a comparative example. Note that in Figure 17 The supply connection channel 323 and the collection connection channel 324 are omitted from the illustration. Ink that has received heat energy from the jetting 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, the jetting element substrate 340 is provided with only the common collection channel 19 in a portion of the X direction, as shown. Figure 17 The portion α, circled by long and short dashed lines, is shown in the diagram. In this case, the temperature may locally rise in this portion, resulting in temperature unevenness within the injection module 300. This temperature unevenness may affect the injection process.

[0160] The temperature of the ink flowing through the common supply channel 18 is lower than the temperature in the common collection channel 19. Therefore, if the common supply channel 18 and the common collection channel 19 are close to each other, the ink in the common supply channel 18, where the temperature is relatively lower at the point where the two channels are close, lowers the temperature of the ink in the common collection channel 19. This suppresses temperature rise. For this purpose, it is preferable that the common supply channel 18 and the common collection channel 19 have substantially the same length, are positioned at a location that overlaps with each other in the X direction, and are close to each other.

[0161] Figure 18A and 18B This diagram illustrates the channel structure of a liquid jet head 1 for three colors of ink: cyan (C), magenta (M), and yellow (Y). In the liquid jet head 1, as shown... Figure 18A As shown, a circulation channel is provided for each ink type. Pressure chamber 12 is positioned along the X-direction, which is the main scanning direction of the liquid jet head 1. Furthermore, as... Figure 18B As shown, the common supply channel 18 and the common collection channel 19 are arranged along the nozzle array, which is an array of nozzles 13. The common supply channel 18 and the common collection channel 19 are arranged to extend in the Y direction, with the nozzle array located between them.

[0162] <Connection between the main unit and the liquid injection head>

[0163] Figure 19This is a schematic structural diagram showing more specifically the connection state of the ink tank 2, the external pump 21, and the liquid ejector head 1, which are the main units of the liquid ejection device 50 in this embodiment, as well as the arrangement of the circulation pump, etc. The liquid ejection device 50 in this embodiment has a structure that allows only the liquid ejector head 1 to be easily replaced in the event of a malfunction. Specifically, the liquid ejection device 50 in this embodiment has a liquid connection 700, through which the ink supply pipes 59 connected to each external pump 21 and the liquid ejector head 1 can be easily connected and disconnected from each other. This allows only the liquid ejector head 1 to be easily attached to and removed from the liquid ejection device 50.

[0164] like Figure 19 As shown, each liquid connection 700 has a liquid connector insertion slot 53a and a cylindrical liquid connector 59a. The liquid connector insertion slot 53a is provided in a protruding manner on the head housing 53 of the liquid ejector head 1, and the liquid connector insertion slot 53a can be inserted into the cylindrical liquid connector 59a. The liquid connector insertion slot 53a is fluidly connected to the ink supply channel (inflow channel) formed in the liquid ejector head 1, and is connected to the first pressure regulating unit 120 through the aforementioned filter 110. The liquid connector 59a is provided at the end of the ink supply pipe 59 connected to the external pump 21, which supplies ink from the ink tank 2 to the liquid ejector head 1 by pressurization.

[0165] As mentioned above, Figure 19 The liquid jet head 1 shown has a liquid connection portion 700. This facilitates the attachment, removal, and replacement of the liquid jet head 1. However, if the sealing performance between the liquid connector insertion slot 53a and the liquid connector 59a deteriorates, ink pressurized and supplied by the external pump 21 may leak from the liquid connection portion 700. For example, if it adheres to the circulation pump 500, the leaked ink may cause malfunctions in the electrical system. To address this issue, in this embodiment, the circulation pump, etc., is configured as follows.

[0166] Arrangement of circulating pumps, etc.

[0167] like Figure 19As shown, in this embodiment, to prevent ink leaking from the liquid connection 700 from adhering to the circulation pump 500, the circulation pump 500 is positioned higher than the liquid connection 700 in the gravity direction. Specifically, the circulation pump 500 is positioned higher than the liquid connector insertion slot 53a in the gravity direction, which is the liquid inlet in the liquid jet head 1. Furthermore, the circulation pump 500 is positioned in a location that does not contact the constituent components of the liquid connection 700. In this way, even if ink leaks from the liquid connection 700, the ink flows horizontally in the opening direction of the liquid connector 59a, or downwards in the gravity direction. This prevents ink from reaching the circulation pump 500, which is positioned higher in the gravity direction. Furthermore, positioning the circulation pump 500 separately from the liquid connection 700 also reduces the possibility of ink reaching the circulation pump 500 through the components.

[0168] Furthermore, the electrical connection portion 515, which connects the circulation pump 500 and the electrical contact substrate 6 via the flexible wiring member 514, is positioned higher than the liquid connection portion 700 in the direction of gravity. This reduces the likelihood of ink from the liquid connection portion 700 causing electrical malfunctions.

[0169] Furthermore, in this embodiment, a wall portion 52b of the head housing 53 is provided. Therefore, even if ink is ejected from the liquid connection portion 700 through the opening 59b, the wall portion 53b will block the ink, thereby reducing the possibility of the ink reaching the circulation pump 500 or the electrical connection portion 515.

[0170] <Ink backflow near the nozzle>

[0171] The features of this embodiment will now be described. Figure 20A and 20B This is a schematic view showing the ink backflow near the nozzle. Figure 20A It is shown schematically. Figure 5 The view of the loop path shown. Figure 20B yes Figure 3B An enlarged view of the injection module shown. Figure 5 and 3B This flow pattern illustrates how ink in pressure chamber 12 flows in from the common supply channel 18, passes through pressure chamber 12, and flows out through the common collection channel 19. As previously described, under continuous high-load printing conditions, ink also flows back into pressure chamber 12 from the collection channel 140 side. That is, as... Figure 20A and 20BAs shown, each pressure chamber 12 is refilled with ink from the supply channel 130 (common supply channel 18) and the collection channel 140 (common collection channel 19). Specifically, ink supplied from the first pressure control chamber 122 to the bypass channel 160 is supplied to the second pressure control chamber 152 of the second pressure regulating unit 150 via the second valve chamber 151. Subsequently, a portion of the ink supplied to the second pressure control chamber 152 is supplied to the collection channel 140 and then to the injection port 13 via the common collection channel 19.

[0172] Figure 21A and 21B This is a view describing the ink supply inside the jetting module 300. Figure 21A This is a view showing the channel configuration near pressure chamber 12, and also a view showing a comparative example different from this embodiment. Figure 21A This indicates a configuration in which only one side of the pressure chamber 12 is connected to the flow channel 2010. In this configuration, ink is supplied to the pressure chamber 12 unilaterally, with ink supplied only from the channel 2010. Figure 21A In the configuration, an independent supply port 2020 communicating with the pressure chamber 12 is connected to a common supply channel 18 or a common collection channel 19, or both. When a thermal jetting element is used as the jetting element 15, ink is ejected from the jetting port 13 by generating bubbles within the pressure chamber 12. Furthermore, the pressure chamber 12 is refilled with ink as the bubbles corresponding to their formation disappear. In this channel structure, the channel 2010 connected to the pressure chamber 12 is narrow and long to increase the back resistance during bubble generation. This makes the generated bubbles more symmetrical and improves droplet formation. On the other hand, in cases such as Figure 21A In the illustrated configuration, the increased back resistance reduces the ease of ink refilling in pressure chamber 12 after the bubbles disappear following ejection. Therefore, utilizing... Figure 21A The channel configuration shown typically makes it difficult to increase refill frequency. In particular, during high-volume printing operations, the amount of ink supplied to each nozzle decreases, potentially leading to reduced jetting stability.

[0173] on the other hand, Figure 21B This diagram illustrates the channel configuration near the pressure chamber 12 in this embodiment. A supply connection channel 323, serving as a first independent supply port, connects a first liquid channel 2030 communicating with the pressure chamber 12 and a common supply channel 18. A collection connection channel 324, serving as a second independent supply port, connects a second liquid channel 2040 communicating with the pressure chamber 12 and a common collection channel 19. As previously described, in this embodiment, the pressure chamber 12 is refilled with the amount of ink ejected from the ejection port 13 via the first liquid channel 2030 and the second liquid channel 2040. Figure 21BAs shown, a dual-sided supply structure is adopted, wherein the two sides of the pressure chamber 12 are connected to the first liquid channel 2030 and the second liquid channel 2040. With this structure, although... Figure 21B As shown, the channel communicating with pressure chamber 12 is wide and short, but it applies symmetrical back resistance when bubbles are generated, making the generated bubbles more symmetrical. This helps improve droplet formation. Furthermore, the back resistance does not need to be increased. This improves the convenience of ink supply during ink refilling in pressure chamber 12 after the bubbles disappear following ejection. As described above, according to this embodiment, ejection stability is improved even under high-load printing operations. That is, both droplet formation and refill frequency are improved.

[0174] Note that the above embodiments primarily describe the use of thermal jetting elements. However, piezoelectric jetting elements can also be used. However, with the thermal type, it is more difficult to improve both droplet formation and refill frequency. Therefore, in this embodiment, the thermal type is preferred.

[0175] <<Variation>>

[0176] Next, various variations of the above embodiment will be described. A configuration where ink flows back from the collection channel 140 towards the pressure chamber 12 requires only the provision of a bypass channel 160, and no mechanism acting as a check valve is provided between the confluence of the bypass channel 160 and the collection channel 140 and the pressure chamber 12. In this embodiment, as previously described, the circulation pump 500 is a pump that delivers liquid in one direction. Therefore, it is sufficient that the confluence of the bypass channel 160 is located upstream of the circulation pump 500. In other words, it is sufficient that the bypass channel 160 allows the upstream and downstream channels to communicate with each other without the pressure chamber 12 in between. This configuration allows the bypass channel 160 to supply liquid to the pressure chamber 12 via the downstream channel.

[0177] <First Variation>

[0178] Figure 22A and 22B as well as Figure 23A and 23B This is a diagram schematically illustrating the loop path in the first variant. Figure 22A and 22B The loop path is shown when the loop is executed but the injection is not. Figure 23A and 23B The loop path is shown under high-load printing conditions. The first variant represents an example where the second pressure regulating unit 150 is not provided, and the bypass channel 160 and the collection channel 140 are directly connected to each other.

[0179] In this configuration, the flow resistance of ink flowing from the bypass channel 160 to the collection channel 140 is denoted as R1, and the flow resistance of ink flowing from the supply channel 130 through the ejection module 300 to the collection channel 140 is denoted as R2. The amount of ink flowing through each channel is inversely proportional to the resistance. Therefore, the ratio of the flow rate through the bypass channel 160 to the flow rate through the ejection module 300 is R2 to R1. Based on this relationship, each flow resistance is set to obtain a circulation amount capable of suppressing ink thickening near the ejection port 13 in the ejection module 300. Specifically, each flow resistance is set such that the flow rate of the liquid in the pressure chamber will be a predetermined flow rate or higher. The flow resistance R1 of the bypass channel 160 is controlled, for example, by changing its channel area or channel length or by providing contraction.

[0180] Similarly, in the first variant, under high-load printing conditions, ink is supplied from both sides to each pressure chamber 12, such as... Figure 23A and 23B As shown. Specifically, ink supplied from the first pressure control chamber 122 to the supply channel 130 is supplied to the ejection port 13 via the common supply channel 18 in the ejection module 300. On the other hand, a portion of the ink supplied from the first pressure control chamber 122 to the bypass channel 160 is supplied to the first pressure control chamber 122 via the circulation pump 500 and the pump outlet channel 180. Furthermore, a portion of the ink supplied to the bypass channel 160 is supplied to the collection channel 140, and then supplied to the ejection port 13 via the common collection channel 19 in the ejection module 300. Therefore, the ink to be ejected from the ejection port 13 is supplied from both the supply channel 130 and the collection channel 140.

[0181] <Second Variation>

[0182] Figure 24A and 24B as well as Figure 25A and 25B This is a diagram schematically illustrating the loop path in the second variation. Figure 24A and 24B The loop path is shown when the loop is executed but the injection is not. Figure 25A and 25B The loop path is shown under high-load printing conditions. The second variation represents an example where the second pressure regulating unit 150 is not provided, the bypass channel 160 and the collection channel 140 are directly connected to each other, and the pressure relief valve 2301 is provided in the bypass channel 160.

[0183] The pressure relief valve 2301 is configured such that ink flows from the upstream side to the downstream side of the pressure relief valve when the downstream pressure reaches a predetermined value or lower. Specifically, the pressure relief valve is configured to open when the pressure on the collection channel side of the pressure relief valve becomes lower than the pressure on the supply channel side of the pressure relief valve by a predetermined amount. The flow of the ink to be supplied is substantially the same as... Figure 5 as well as Figure 20A and 20B The second pressure regulating unit 150 is constructed in the same way as shown. The pressure difference between the controlled pressure in the first pressure control chamber 122 and the controlled pressure in the pressure relief valve 2301 determines the circulation volume within the injection module 300. The controlled pressure in the pressure relief valve 2301 is set to obtain a circulation volume that can suppress ink thickening near the injection port 13 in the injection module 300.

[0184] Similarly, in the second variant configuration, under high-load printing conditions, ink is supplied from both sides to each pressure chamber 12, as... Figure 25A and 25B As shown. Specifically, ink supplied from the first pressure control chamber 122 to the supply channel 130 is supplied to the nozzle 13 via the common supply channel 18 in the ejection module 300. On the other hand, a portion of the ink supplied from the first pressure control chamber 122 to the bypass channel 160 passes through the pressure relief valve 2301 and is supplied to the first pressure control chamber 122 via the circulation pump 500 and the pump outlet channel 180. Furthermore, a portion of the ink supplied to the bypass channel 160 passes through the pressure relief valve 2301, is supplied to the collection channel 140, and then is supplied to the nozzle 13 via the common collection channel 19 in the ejection module 300. Therefore, the ink to be ejected from the nozzle 13 is supplied from both the supply channel 130 and the collection channel 140.

[0185] <Third Variation>

[0186] Next, the various variations of the circulation channel will be collectively referred to as the third variation. As mentioned earlier, the configuration in which ink flows back from the collection channel 140 to the pressure chamber 12 only requires the provision of a bypass channel 160, and no mechanism acting as a check valve is provided between the confluence of the bypass channel 160 and the pressure chamber 12. Therefore, by utilizing a circulation channel that can maintain this relationship, ink can be supplied to the pressure chamber 12 from both sides, and thus the jetting stability can be improved.

[0187] Figure 26 It is a schematic diagram illustrating the loop path. Figure 26 This illustrates an example where the pump outlet passage 180, located downstream of the circulating pump 500, is configured to connect to the ink tank 2 (instead of the first pressure control chamber 122). Similar to the configuration described above, this configuration can also improve jet stability.

[0188] Figure 27It is a schematic diagram illustrating the loop path. Figure 27 An example is shown in which each circulation pump 500, which is installed in the liquid injection head 1 described above, is mounted on a bracket 60 on the main body side of the liquid injection device 50. This configuration also causes the pump inlet passage 170 and the pump outlet passage 180 to be partially located outside the liquid injection head 1. Similar to the configuration described above, this configuration can also improve injection stability.

[0189] exist Figure 27 In this configuration, a circulation pump 500 is mounted on a bracket 60 on the main body side of the liquid injection device 50, and a first pressure regulating unit 120 and a second pressure regulating unit 150 are mounted in the liquid injection head 1. Note that one or both of the first pressure regulating unit 120 and the second pressure regulating unit 150 can be mounted on the bracket 60 on the main body side of the liquid injection device 50. When the first pressure regulating unit 120 is mounted on the bracket 60 on the main body side of the liquid injection device 50, this configuration causes the first channel 130 to be partially located outside the liquid injection head 1. When the second pressure regulating unit 150 is mounted on the bracket 60 on the main body side of the liquid injection device 50, this configuration causes the second channel 140 to be partially located outside the liquid injection head 1.

[0190] Figure 28 It is a schematic diagram illustrating the loop path. Figure 28 An example is shown in which each circulation pump 500, installed in the liquid jet head 1 described above, is mounted on the main body side of the liquid jetting device 50, and the pump outlet channel 180 is connected to the corresponding ink tank 2. Similar to the above configuration, this configuration can also improve jetting stability.

[0191] <Fourth Variation>

[0192] Figure 29 The diagram illustrates the circulation path in the fourth variant. The fourth variant represents an example including a second supply channel 600 through which the first pressure control chamber 122 of the first pressure regulating unit 120 and the supply channel 130 are connected to each other.

[0193] When the liquid injection head 1 is in use, the second supply channel 600 is connected at one end to the upper end of the first pressure control chamber 122 in the direction of gravity, and at the other end to the supply channel 130 (the first channel), which is located below the first end in the vertical direction. Here, "in use" refers to the state in which the liquid injection head 1 is in use, i.e. Figure 2 The state in which the nozzle for spraying liquid is oriented downward in the vertical direction. Through the second supply channel 600, bubbles that have flowed into the first pressure regulating unit 120 from the upstream side or bubbles generated in the circulation channel are effectively discharged to the outside.

[0194] Specifically, the first pressure control chamber 122 of the first pressure regulating unit 120 is positioned on the upper side of the liquid ejector head 1 in the direction of gravity. Therefore, bubbles BL that have flowed into the first pressure regulating unit 120 from the upstream side of the liquid ejector head 1 along with ink, or bubbles BL that have flowed into the first pressure control chamber 122 from the circulation channel, rise to the upper part of the first pressure control chamber 122 or the upper part of the second supply channel 600, and accumulate there. Note that during inkjet operation, the accumulated bubbles BL do not move to the ejection module 300 due to the flow rate of the liquid flowing through the supply channel 130 and the second supply channel 600. Therefore, the second supply channel 600 is also referred to as an "air accumulation channel".

[0195] The air bubbles BL accumulating in the upper part of the first pressure control chamber 122 and the second supply channel 600 can be discharged along with the ink by performing a forced ink suction process from the nozzle without performing liquid jetting operation. This suction process is performed by bringing the cover member into close contact with the nozzle surface of the liquid jet head 1, and applying negative pressure from a negative pressure source connected to the cover member to the nozzle, thereby forcibly suctioning ink from the nozzle. During this suction process, the flow rate of the ink generated in the channel is higher than that generated during normal inkjet operation. Therefore, the air bubbles BL accumulating in the upper part of the first pressure control chamber 122 and the second supply channel 600 move with the ink through the second supply channel 600 and the supply channel 130 to the pressure chamber 12, and then are discharged from the nozzle 13 along with the ink. Note that this suction process is typically performed during suction recovery processes, initial filling processes where ink is filled into the channels, etc., to restore jetting performance by discharging thickened ink, etc., that appears in the nozzle, pressure chamber, etc., from the nozzle.

[0196] As described above, by forming a second supply channel, air bubbles contained in the ink within the liquid jet head 1 can be aggregated and immediately expelled through a suction process. Therefore, the process of expelling air bubbles can be performed effectively.

[0197] <Fifth Variation>

[0198] Figure 1A The liquid jet head 1 shown is described as an example of a so-called tandem liquid jet head, which jets ink while moving along the main scanning direction, but is not limited thereto. The liquid jet head 1 can be a so-called full-line liquid jet head, wherein the jet nozzle is formed over the entire width of the printing medium P, and is capable of jetting ink onto the entire area of ​​the printing medium P in the width direction without moving in the main scanning direction.

[0199] <Sixth Variation>

[0200] Figure 30This is a schematic diagram illustrating the circulation path in the sixth variant. In this sixth variant, neither the first pressure regulating unit 120 nor the second pressure regulating unit 150 is included. Even in this configuration, by including a bypass channel 160, liquid can flow back from the collection channel 140 to the pressure chamber 12, as described above, whereby the upstream and downstream channels are connected to each other via the bypass channel 160, without the pressure chamber 12 in between.

[0201] Alternatively, a configuration may be adopted that has only one of the first pressure regulating unit 120 or the second pressure regulating unit 150.

[0202] <<Other Embodiments>>

[0203] The disclosure of this embodiment includes constructions represented by the following examples of liquid jet head and liquid jet device.

[0204] <Construction 1>

[0205] A liquid injection head includes: a pressure chamber in which pressure is applied by an injection element configured to generate pressure for injecting liquid from an injection port; an upstream passage communicating with the pressure chamber and configured to supply liquid to the pressure chamber; a downstream passage communicating with the pressure chamber; a pump communicating with the upstream and downstream passages and configured to allow liquid in the downstream passage to flow into the upstream passage; an inflow passage communicating with the upstream passage and configured to allow liquid to be supplied to the pressure chamber to flow into the upstream passage; and a bypass passage through which the upstream and downstream passages are connected to each other, wherein there is no pressure chamber between the upstream and downstream passages, wherein a portion of the liquid flowing from the upstream passage into the bypass passage flows into the pressure chamber through the downstream passage.

[0206] <Construction 2>

[0207] According to the liquid jet head of configuration 1, the pump includes a check valve in a channel, and the downstream channel and the upstream channel are connected to each other through the channel.

[0208] <Construction 3>

[0209] According to the liquid jet head described in configuration 1 or 2, the upstream channel includes a first pressure regulating unit communicating with the inflow channel, a first channel through which the first pressure regulating unit and the pressure chamber communicate with each other, and a third channel through which the pump and the first pressure regulating unit communicate with each other, and the first pressure regulating unit is configured to regulate the pressure in the first channel.

[0210] <Construction 4>

[0211] According to the liquid injection head of configuration 3, the first pressure regulating unit includes a valve chamber, a pressure control chamber, an opening, and a valve. The pressure control chamber has a surface formed by a flexible member configured to be displaceable. The valve chamber and the pressure control chamber are in communication with each other through the opening. The valve is configured to open and close the opening. The pressure control chamber includes a pressure plate displaceable together with the flexible member and a biasing member configured to bias the pressure plate in a direction of increasing volume of the pressure control chamber. The pressure control chamber is configured to open and close the valve according to the displacement of the pressure plate and the flexible member.

[0212] <Construction 5>

[0213] According to the liquid injection head described in configuration 4, the inflow channel is connected to the valve chamber of the first pressure regulating unit.

[0214] <Construction 6>

[0215] According to the liquid injection head described in configuration 4 or 5, the first channel, the third channel, and the bypass channel are connected to the pressure control chamber of the first pressure regulating unit.

[0216] <Construction 7>

[0217] According to any one of constructions 3 to 6, a liquid injection head is provided in the bypass channel, wherein the pressure relief valve is configured to open when the pressure in the downstream channel becomes lower than the pressure in the first channel by a predetermined amount.

[0218] <Construction 8>

[0219] According to any one of the constructions 1 to 7, the flow resistance of the bypass channel is set such that when the pump is driven, the flow rate of the liquid in the pressure chamber is a predetermined flow rate or higher, thereby circulating the liquid through the pressure chamber.

[0220] <Construction 9>

[0221] According to any one of constructions 4 to 6, the liquid injection head includes a pressure control chamber of the first pressure regulating unit that communicates with the first channel, and wherein, when the liquid injection head is in use, one end of the air accumulation channel is communicated with the upper end of the pressure control chamber of the first pressure regulating unit, and the other end of the air accumulation channel is communicated with the first channel, wherein the first channel is lower than the one end in the direction of gravity.

[0222] <Construction 10>

[0223] According to any one of constructions 1 to 9, the liquid injection head, wherein the downstream channel includes a second pressure regulating unit, a pressure chamber and a second channel through which the second pressure regulating unit communicates with each other, and a fourth channel through which the second pressure regulating unit and the pump communicate with each other, wherein the second pressure regulating unit is configured to regulate the pressure in the second channel, and wherein a bypass channel supplies liquid to the pressure chamber through the second pressure regulating unit and the second channel.

[0224] <Construction 11>

[0225] According to the liquid injection head of configuration 10, the second pressure regulating unit includes a valve chamber, a pressure control chamber, an opening, and a valve. The pressure control chamber has a surface formed by a flexible member configured to be displaceable. The valve chamber and the pressure control chamber communicate with each other through the opening. The valve is configured to open and close the opening. The pressure control chamber includes a pressure plate displaceable together with the flexible member and a biasing member configured to bias the pressure plate in a direction of increasing volume of the pressure control chamber. The pressure control chamber is configured to open and close the valve according to the displacement of the pressure plate and the flexible member.

[0226] <Construction 12>

[0227] According to the liquid injection head of configuration 11, the bypass channel is connected to the valve chamber of the second pressure regulating unit.

[0228] <Construction 13>

[0229] According to the liquid injection head described in construction 11 or 12, the pressure control chamber of the second pressure regulating unit is connected to the second channel and the fourth channel.

[0230] <Construction 14>

[0231] The liquid jet head according to any one of constructions 1 to 13 further includes a jetting unit configured to jet liquid and a circulation unit configured to circulate liquid between the jetting unit and the circulation unit, wherein the circulation unit includes a pump and the jetting unit includes a jet nozzle and a pressure chamber.

[0232] <Construction 15>

[0233] A liquid jetting device includes a liquid jetting head configured to jettison liquid, wherein the liquid jetting head includes: a pressure chamber in which pressure generated by a jetting element configured to generate pressure is applied, wherein the pressure is used to jettison liquid from a jetting port; an upstream passage communicating with the pressure chamber and configured to supply liquid to the pressure chamber; a downstream passage communicating with the pressure chamber; a pump communicating with the upstream and downstream passages and configured to allow liquid in the downstream passage to flow into the upstream passage; an inflow passage communicating with the upstream passage and configured to allow liquid to be supplied to the pressure chamber to flow into the upstream passage; and a bypass passage through which the upstream and downstream passages communicate with each other, wherein there is no pressure chamber between the upstream and downstream passages, and wherein a portion of the liquid flowing from the upstream passage into the bypass passage flows into the pressure chamber through the downstream passage.

[0234] <Construction 16>

[0235] A liquid jetting device includes: a liquid jetting head configured to jet liquid; a circulation unit including a pump configured to circulate liquid between the liquid jetting head and the circulation unit; and a bracket including a liquid jetting head mounting unit and a circulation unit mounting unit, the liquid jetting head being mounted on the liquid jetting head mounting unit and the circulation unit being mounted on the circulation unit mounting unit, wherein the liquid jetting head includes: a pressure chamber in which pressure generated by a jetting element configured to generate pressure is applied, wherein the pressure is used to jet liquid from a jetting port; an upstream passage communicating with the pressure chamber and configured to supply liquid to the pressure chamber; and a downstream passage communicating with the pressure chamber, an inflow passage configured to allow liquid to be supplied to the pressure chamber to flow into the upstream passage communicating with the upstream passage, the pump communicating with the upstream passage and the downstream passage and allowing liquid in the downstream passage to flow into the upstream passage, and the liquid jetting head including a bypass passage through which the upstream passage and the downstream passage are communicated with each other without a pressure chamber between the upstream passage and the downstream passage, and a portion of the liquid flowing from the upstream passage into the bypass passage flowing into the pressure chamber through the downstream passage.

[0236] <Construction 17>

[0237] According to configuration 15 or 16, the liquid jetting device further includes an ink tank configured to contain liquid, wherein the inflow channel is a flow channel communicating the ink tank and the liquid jetting head with each other, and the inflow channel is configured to allow liquid in the ink tank to flow into the liquid jetting head.

[0238] <Construction 18>

[0239] According to any one of constructions 15 to 17, the liquid injection device includes a downstream channel comprising a pressure regulating unit configured to regulate pressure in the downstream channel, and wherein the bypass channel is connected to the pressure regulating unit.

[0240] <Construction 19>

[0241] According to the liquid injection device of configuration 18, the pressure regulating unit includes a valve chamber, a pressure control chamber, and an opening, the valve chamber and the pressure control chamber being in communication with each other through the opening, the valve chamber including a valve configured to open and close the opening according to pressure changes in the pressure control chamber, and the bypass passage being connected to the valve chamber in the pressure regulating unit.

[0242] <Construction 20>

[0243] According to any one of constructions 15 to 19, the liquid jetting device is wherein the carriage moves relative to the printing medium, and the liquid is jetted from the liquid jetting head onto the printing medium.

[0244] Embodiments of the present invention can also be implemented by a computer of a system or device, which reads and executes computer-executable instructions (e.g., one or more programs) recorded on a storage medium (more comprehensively referred to as a "non-transitory computer-readable storage medium") to perform the functions of one or more of the above embodiments and / or includes one or more circuits (e.g., application-specific integrated circuits (ASICs)) for performing the functions of one or more of the above embodiments. Embodiments of the present invention can also be implemented by a method executed by a computer of a system or device, such as by reading and executing computer-executable instructions from a storage medium to perform the functions of one or more of the above embodiments and / or by controlling one or more circuits to perform the functions of one or more of the above embodiments. The computer may include one or more processors (e.g., a central processing unit (CPU), a microprocessor unit (MPU)) and may include a network of individual computers or individual processors to read and execute the computer-executable instructions. The computer-executable instructions may be provided to the computer, for example, from a network or a storage medium. The storage medium may include, for example, a hard disk, random access memory (RAM), read-only memory (ROM), the memory of a distributed computing system, an optical disk (e.g., a compact disc (CD), a digital versatile disc (DVD), or a Blu-ray disc). TM One or more of the following: (BD), flash memory device, memory card, etc.

[0245] Other embodiments

[0246] The embodiments of the present invention can also be implemented by providing software (programs) that perform the functions of the above embodiments to a system or device via a network or various storage media, and the computer or central processing unit (CPU) or microprocessor unit (MPU) of the system or device reads out and executes the program.

[0247] Although this disclosure has been described with reference to exemplary embodiments, it should be understood that this disclosure is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be interpreted in the broadest sense so as to encompass all such variations and equivalent structures and functions.

Claims

1. A liquid injection head, comprising: A pressure chamber in which pressure is applied by a jet element configured to generate pressure, wherein the pressure is used to eject liquid from a jet nozzle; An upstream channel, which communicates with the pressure chamber and is configured to supply liquid to the pressure chamber; Downstream passage connected to the pressure chamber; A pump, which is connected to an upstream channel and a downstream channel and is configured to allow liquid in the downstream channel to flow into the upstream channel; An inflow channel, which is connected to an upstream channel and is configured to allow liquid to be supplied to the pressure chamber to flow into the upstream channel; and The bypass channel connects the upstream and downstream channels, but there is no pressure chamber between the upstream and downstream channels. A portion of the liquid flowing from the upstream channel into the bypass channel flows into the pressure chamber through the downstream channel.

2. The liquid injection head according to claim 1, wherein, The pump includes a check valve located in a channel, through which the downstream channel and the upstream channel are connected to each other.

3. The liquid injection head according to claim 2, The upstream channel includes: The first pressure regulating unit is connected to the inflow channel. The first channel, the first pressure regulating unit, and the pressure chamber are interconnected through the first channel, and The third channel connects the pump and the first pressure regulating unit to each other, and The first pressure regulating unit is configured to regulate the pressure in the first channel.

4. The liquid injection head according to claim 3, in, The first pressure regulating unit includes: Valve chamber, A pressure control chamber having a surface formed by a flexible member configured to be movable. The opening connects the valve chamber and the pressure control chamber to each other. A valve constructed to open and close its opening. The pressure control chamber includes: A pressure plate capable of co-moving with the flexible member, and A biasing member is configured to bias the pressure plate in the direction of increasing volume of the pressure control chamber, and The pressure control chamber is configured to open and close the valve based on the displacement of the pressure plate and the flexible member.

5. The liquid injection head according to claim 4, wherein, The inflow channel is connected to the valve chamber of the first pressure regulating unit.

6. The liquid injection head according to claim 4, wherein, The first channel, the third channel, and the bypass channel are connected to the pressure control chamber of the first pressure regulating unit.

7. The liquid injection head according to claim 4, The pressure relief valve is located in the bypass channel, and The pressure relief valve is configured to open when the pressure in the downstream channel becomes lower than the pressure in the first channel by a predetermined amount.

8. The liquid injection head according to claim 2, wherein, The flow resistance of the bypass channel is set such that when the pump is driven, the flow rate of the liquid in the pressure chamber is a predetermined flow rate or greater, thereby circulating the liquid through the pressure chamber.

9. The liquid injection head according to claim 4, in, The pressure control chamber of the first pressure regulating unit includes an air accumulation channel communicating with the first channel, and In the case where the liquid injection head is in use, one end of the air accumulation channel is connected to the upper end of the pressure control chamber of the first pressure regulating unit, and the other end of the air accumulation channel is connected to the first channel, which is located below the one end in the direction of gravity.

10. The liquid injection head according to claim 2, The downstream channel includes: Second pressure regulating unit, The second channel connects the pressure chamber and the second pressure regulating unit to each other. The fourth channel connects the second pressure regulating unit and the pump to each other, and The second pressure regulating unit is configured to regulate the pressure in the second channel, and The bypass channel supplies liquid to the pressure chamber through the second pressure regulating unit and the second channel.

11. The liquid injection head according to claim 10, in, The second pressure regulating unit includes: Valve chamber, A pressure control chamber having a surface formed by a flexible member configured to be movable. The opening connects the valve chamber and the pressure control chamber to each other. A valve constructed to open and close its opening. The pressure control chamber includes: A pressure plate capable of co-moving with the flexible member, and A biasing member is configured to bias the pressure plate in the direction of increasing volume of the pressure control chamber, and The pressure control chamber is configured to open and close the valve based on the displacement of the pressure plate and the flexible member.

12. The liquid injection head according to claim 11, wherein, The bypass channel is connected to the valve chamber of the second pressure regulating unit.

13. The liquid injection head according to claim 11, wherein, The pressure control chamber of the second pressure regulating unit is connected to the second channel and the fourth channel.

14. The liquid injection head according to claim 1, further comprising: The injection unit, which is configured to inject liquid; and The circulation unit is configured to circulate liquid between the injection unit and the circulation unit. in, The circulation unit includes a pump, and the injection unit includes an injection port and a pressure chamber.

15. A liquid jetting device, comprising: A liquid injection head, which is configured to inject liquid; The liquid injection head is mounted on the bracket. and The liquid injection head includes: A pressure chamber, in which pressure is applied by a jet element configured to generate pressure, wherein this pressure is used to eject liquid from a jet nozzle. An upstream channel, which communicates with the pressure chamber and is configured to supply liquid to the pressure chamber. Downstream passage connected to the pressure chamber, A pump, which is connected to an upstream channel and a downstream channel, and is configured to allow liquid in the downstream channel to flow into the upstream channel. An inflow channel, which communicates with the upstream channel and is configured such that liquid to be supplied to the pressure chamber flows into the upstream channel, and The bypass channel connects the upstream and downstream channels, but there is no pressure chamber between the upstream and downstream channels. A portion of the liquid flowing from the upstream channel into the bypass channel flows into the pressure chamber through the downstream channel.

16. A liquid jetting device, comprising: A liquid injection head, which is configured to inject liquid; A circulation unit, which includes a pump configured to circulate liquid between a liquid jet head and the circulation unit; and The bracket includes a liquid injection head mounting unit with a liquid injection head and a circulation unit mounting unit with a circulation unit, wherein... The liquid injection head includes: A pressure chamber, in which pressure is applied by a jet element configured to generate pressure, wherein this pressure is used to eject liquid from a jet nozzle. An upstream channel, which communicates with the pressure chamber and is configured to supply liquid to the pressure chamber, and Downstream passage connected to the pressure chamber; The inflow channel is configured to allow the liquid to be supplied to the pressure chamber to flow into the upstream channel and is in communication with the upstream channel; The pump is connected to both the upstream and downstream channels, and allows liquid in the downstream channel to flow into the upstream channel; and The liquid injection head includes a bypass channel, through which an upstream channel and a downstream channel are connected to each other without a pressure chamber between the upstream and downstream channels, and a portion of the liquid flowing from the upstream channel into the bypass channel flows into the pressure chamber through the downstream channel.

17. The liquid jetting apparatus of claim 15 or 16, further comprising an ink reservoir configured to contain liquid. in, The inflow channel is a flow channel that connects the ink tank and the liquid jet head to each other, and is configured to allow liquid in the ink tank to flow into the liquid jet head.

18. The liquid jetting device according to claim 15 or 16, wherein, The downstream channel includes a pressure regulating unit configured to regulate the pressure in the downstream channel. The bypass channel is connected to the pressure regulating unit.

19. The liquid jetting device according to claim 18, wherein The pressure regulating unit includes a valve chamber, a pressure control chamber, and an opening, through which the valve chamber and the pressure control chamber are connected to each other. The valve chamber includes a valve configured to open and close the opening based on pressure changes in the pressure control chamber. The bypass channel is connected to the valve chamber in the pressure regulating unit.

20. The liquid jetting device according to claim 15 or 16, wherein, The carriage moves relative to the printing medium, and liquid is sprayed from the liquid jet head onto the printing medium.

21. A liquid injection head, comprising: A pressure chamber in which pressure is applied by a jet element configured to generate pressure, wherein the pressure is used to eject liquid from a jet nozzle; A first connection channel, which communicates with a pressure chamber and is configured to supply liquid to the pressure chamber; A second connecting channel that communicates with the pressure chamber; A pump, which is connected to a first connection channel and a second connection channel and is configured to allow liquid in the second connection channel to flow into the first connection channel; An inflow channel, which is connected to a first connecting channel and configured to allow liquid to be supplied to the pressure chamber to flow into the first connecting channel; and The bypass channel connects the first connecting channel and the second connecting channel to each other, but there is no pressure chamber between the first connecting channel and the second connecting channel. A portion of the liquid flowing from the first connecting channel into the bypass channel flows into the pressure chamber through the second connecting channel.

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