Liquid ejecting head and liquid ejecting apparatus

Abstract

The present disclosure relates to a liquid ejection head including a pressure chamber communicating with an ejection port, an ejection element ejecting liquid from the ejection port, and a liquid circulation path including the pressure chamber. The circulation path includes a supply passage for supplying liquid to the pressure chamber, a recovery passage for recovering liquid from the pressure chamber, a circulation pump supplying the recovered liquid to the supply passage, and a pressure regulating unit configured to regulate a pressure of the liquid supplied to the supply passage. A pressure P21 of the liquid supplied to the pressure chamber when the circulation pump is stopped, a pressure P22 of the liquid supplied to the pressure chamber when the circulation pump is driven, and a pressure loss ΔP from the pressure regulating unit to the pressure chamber when the circulation pump is driven satisfy P22 > P21 and P22 - ΔP < 0. The present disclosure also relates to a liquid ejection apparatus.

Description

Technical Field

[0001] This disclosure relates to a liquid jet head including a liquid circulation path, and to a liquid jetting device including the liquid jet head. Background Technology

[0002] Some liquid jetting devices circulate the liquid for purposes such as preventing pigment settling and ink thickening. Japanese Patent Application Publication No. 2019-64254 discloses a liquid jetting device that circulates the liquid between a liquid jetting head that jets the liquid and a liquid storage unit that stores the liquid to be supplied to the liquid jetting head. In this device, a circulation path is formed so that ink in the liquid storage unit is supplied to the liquid jetting head through a supply channel, and liquid not jetted from the liquid jetting head is returned to the liquid storage unit through a recovery channel for recycling.

[0003] In liquid jetting apparatuses, during liquid jetting operations, it is preferable to redisperse settled components (e.g., pigments and agglomerates) in the ink that have settled within the path and suppress ink thickening. Therefore, liquid jetting apparatuses that include a liquid circulation path circulate the liquid before the jetting operation. Here, in the liquid jetting apparatus disclosed in Japanese Patent Application Publication No. 2019-64254, a long circulation path is formed extending from the liquid storage unit to the liquid jetting head and then returning to the liquid storage unit. Therefore, in order to redisperse settled components and suppress ink thickening, the liquid needs to circulate through this long circulation path before the jetting operation. This results in long downtime and thus reduces productivity. Summary of the Invention

[0004] The purpose of this invention is to provide a liquid jetting head and a liquid jetting device that can redisperse settled components and suppress ink thickening by performing cycles within a short period of time, thereby reducing downtime.

[0005] In a first aspect of this disclosure, a liquid injection head is provided, comprising: an injection port from which liquid is injected; a pressure chamber in communication with the injection port; an injection element configured to inject liquid supplied to the pressure chamber from the injection port; and a circulation path through which liquid circulates, wherein the circulation path includes: a supply channel through which liquid is supplied to the pressure chamber; a recovery channel through which liquid is recovered from the pressure chamber via the recovery channel; a circulation pump that supplies the liquid recovered via the recovery channel to the supply channel; and a pressure regulating unit configured to regulate the pressure of the liquid supplied to the supply channel, wherein the pressure P21 of the liquid supplied from the pressure regulating unit to the pressure chamber via the supply channel when the circulation pump is stopped, the pressure P22 of the liquid supplied from the pressure regulating unit to the pressure chamber via the supply channel when the circulation pump is driven, and the pressure loss ΔP from the pressure regulating unit to the pressure chamber when the circulation pump is driven have the relationship P22>P21 and P22-ΔP<0.

[0006] In a second aspect of this disclosure, a liquid ejection apparatus is provided, comprising: a liquid ejection head; a liquid supply source supplying liquid to the liquid ejection head; and a delivery unit configured to deliver printing media at a position opposite to an ejection port of the liquid ejection head, the liquid ejection head including: an ejection port from which liquid is ejected; a pressure chamber communicating with the ejection port; an ejection element configured to eject the liquid supplied to the pressure chamber from the ejection port; and a circulation path through which liquid circulates, wherein the circulation path includes: a supply channel through which liquid is supplied to the pressure chamber; and a recovery channel from the pressure chamber. Liquid is recovered through the recovery channel; a circulation pump supplies the liquid recovered through the recovery channel to the supply channel; and a pressure regulating unit configured to regulate the pressure of the liquid supplied to the supply channel, wherein the pressure P21 of the liquid supplied from the pressure regulating unit to the pressure chamber through the supply channel when the circulation pump is stopped, the pressure P22 of the liquid supplied from the pressure regulating unit to the pressure chamber through the supply channel when the circulation pump is driven, and the pressure loss ΔP from the pressure regulating unit to the pressure chamber when the circulation pump is driven have the relationship P22>P21 and P22-ΔP<0.

[0007] Further features of the invention will become apparent from the following description of exemplary embodiments with reference to the accompanying drawings. Attached Figure Description

[0008] Figure 1A and Figure 1B To illustrate the perspective view and block diagram of the liquid injection device;

[0009] Figure 2 An exploded perspective view of the liquid injection head;

[0010] Figure 3A and Figure 3B The images show a longitudinal sectional view of the liquid injection head and an enlarged sectional view of the injection module.

[0011] Figure 4 This is a schematic diagram of the appearance of the loop unit;

[0012] Figure 5 A longitudinal sectional view showing the loop path;

[0013] Figure 6 A block diagram illustrating the loop path;

[0014] Figures 7A to 7C A cross-sectional view showing an example of a pressure regulating unit;

[0015] Figure 8A and Figure 8B External perspective view of the circulating pump;

[0016] Figure 9 for Figure 8A The diagram shows a cross-sectional view of the circulating pump along line IX-IX;

[0017] Figure 10A and Figure 10B An exploded perspective view of the circulating pump;

[0018] Figure 11 A view showing the electrical connection of the piezoelectric ceramic;

[0019] Figures 12A to 12E A diagram illustrating the flow of ink inside a liquid ejector head;

[0020] Figure 13A and Figure 13B A schematic diagram illustrating the circulation path in the injection unit;

[0021] Figure 14 To show a view of the opening plate;

[0022] Figure 15 A view showing the substrate of the spray element;

[0023] Figures 16A to 16C A cross-sectional view showing the ink flow in the jetting unit;

[0024] Figure 17A and Figure 17BTo show a cross-sectional view near the injection nozzle;

[0025] Figure 18A and Figure 18B A cross-sectional view showing a comparative example near the injection nozzle;

[0026] Figure 19 A view showing a comparative example of a jetting element substrate;

[0027] Figure 20A and Figure 20B A view showing the channel configuration of the liquid injection head;

[0028] Figure 21 A diagram showing the connection between the main body unit and the liquid injection head of the liquid injection device; and

[0029] Figure 22 This is a longitudinal sectional view of the liquid injection head in the second embodiment. Detailed Implementation

[0030] Preferred embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. It should be noted 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 solutions provided in the present disclosure. It should be noted that the same constituent elements are denoted by the same reference numerals. In the examples used to describe the embodiments of the present disclosure, a thermal injection element that generates bubbles using an electrothermal conversion element to spray liquid is used as the various injection elements for spraying liquid, but this is not limited to such examples. The embodiments of the present disclosure are also applicable to liquid injection heads employing injection methods using piezoelectric elements and liquid injection heads employing other injection methods. Furthermore, the pumps, pressure regulating units, etc., described below are not limited to the configurations described in the embodiments and shown in the drawings.

[0031] (First Embodiment)

[0032] <Liquid jetting device>

[0033] Figure 1A This is a view used to describe a liquid injection device, and is an enlarged view of the liquid injection head and its vicinity. First, refer to... Figure 1A and 1B A schematic configuration of the liquid injection 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. In this embodiment, the liquid jetting device 50 is configured as a serial inkjet printing device, which performs printing on a printing medium P by jetting ink as a liquid while scanning the liquid jetting head 1.

[0034] The liquid jet head 1 is mounted on a carriage 60. The carriage 60 reciprocates along a guide shaft 51 in the main scanning direction (X direction). The printing media P is conveyed by transport rollers (transport units) 55, 56, 57, and 58 in a secondary scanning direction (Y direction) that intersects (perpendicularly in this example) the main scanning direction. Note that in the figures mentioned below, the Z direction represents the vertical direction and intersects (perpendicularly in this example) 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 carriage 60 by the user.

[0035] Liquid injection head 1 includes circulation unit 54 and injection unit 3, which will be described later (see below). Figure 3A and Figure 3B Although the specific configuration will be described below, the injection unit 3 includes an energy generating element (hereinafter referred to as the "injection element") and a plurality of injection ports, the energy generating element generating injection energy for ejecting liquid from the respective injection ports.

[0036] The liquid jetting device 50 is also provided with an ink cartridge 2, which serves as an ink supply source (liquid supply source), and an external pump 21. The ink held in the ink cartridge 2 is supplied to the circulation unit 54 via the ink supply pipe 59 by the driving force of the external pump 21.

[0037] The liquid jetting device 50 forms a predetermined image on the printing medium P through repeated printing scans (which involve ejecting ink while the liquid jetting head 1 mounted on the carriage 60 moves along the main scanning direction) and transport operations (which involve transporting the printing medium P along the sub-scanning direction). It should be noted 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 uses 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 disclosure also applies 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.

[0038] Furthermore, in the liquid jetting device 50, a cover member (not shown) capable of covering the nozzle surface (where the nozzle is formed) of the liquid jetting head 1 is provided at a position separate from the transport path of the printing medium P in the X direction. 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 for operations such as drawing ink from the nozzle.

[0039] Please note, Figure 1AThe liquid ejector head 1 shown represents an example of including four circulation units 54 corresponding to four types of ink, but it is sufficient as long as the included circulation units 54 correspond to the type of liquid to be ejected. Furthermore, multiple circulation units 54 may be included for the same type of liquid. In summary, the liquid ejector head 1 can have a configuration including one or more circulation units. The liquid ejector head 1 can be configured not to circulate all four types of ink, but to circulate only at least one type of ink.

[0040] Figure 1B This diagram illustrates 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 a processing program stored in the ROM 101. The RAM 102 serves as a workspace for the CPU 103 to perform processing. The CPU 103 receives image data from the host device 400 external to the liquid jetting device 50 and controls the head driver 1A to control the driving of the jetting elements provided in the jetting unit 3. The CPU 103 also controls the drivers used for various actuators provided in the liquid jetting device 50. For example, the CPU 103 controls the motor driver 105A for the carriage motor 105 used to move the carriage 60, the motor driver 104A for the transport motor 104 used to transport 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 configuration shown is for receiving image data from the host device 400 and performing processing; however, the liquid jetting device 50 can perform processing regardless of whether data is provided from the host device 400.

[0041] <Basic Configuration of Liquid Jet Heads>

[0042] Figure 2 This is an exploded perspective view 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 line IIIA-IIIA. Figure 3A This is a longitudinal sectional view of the entire liquid injection head 1, and Figure 3B yes Figure 3A The image shown is an enlarged view of the injection module. The following will primarily refer to this. Figures 2 to 3B and appropriate reference Figure 1A This section describes the basic configuration of the liquid injection head 1 in this embodiment.

[0043] like Figure 2As 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 carriage 60 by a positioning unit and electrical contacts (not shown) provided for the carriage 60 of the liquid ejection device 50. The liquid ejection head 1 ejects ink along the carriage 60... Figure 1A The main scanning direction (X direction) shown is shown. Ink is ejected while the carriage 60 moves together to perform printing on the printing medium P.

[0044] The external pump 21 connected to the ink cartridge 2, which serves as the ink supply source, includes an ink supply tube 59 (see [link]). Figure 1A The liquid connector 59a, described later (see below) Figure 21 The ink supply tubes 59 are located 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 59a, described later, located at the end of the ink supply tube 59, is hermetically connected to a liquid connector insertion slot 53a, which is an inlet located on the head housing 53 of the liquid ejector head 1 through which liquid is introduced. As a result, an ink supply path is formed extending from the ink cartridge 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 cartridge 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 cartridge 2 located 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 recovery system for recovering ink from the liquid ejector head 1 back to the ink cartridge 2. Therefore, the liquid ejector head 1 includes a liquid connector insertion slot 53a for connecting the ink supply tube 59 of the ink cartridge 2, but does not include a connector insertion slot for connecting the ink recovery tube used to recover ink from the liquid ejector head 1 into the ink cartridge 2. Note that a liquid connector insertion slot 53a is provided for each type of ink.

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

[0046] exist Figure 2 and Figure 3AIn 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 (electrical wiring tape) 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. Power is supplied to each spraying element 15 via electrical wiring formed on the silicon substrate 310 using a film deposition technique.

[0047] Furthermore, the outlet forming member 320 is formed on the surface of the silicon substrate 310. Figure 3B On the lower surface of the ink jetting module 310. In the outlet forming member 320, multiple pressure chambers 12 corresponding to multiple jetting elements 15 and multiple jetting nozzles 13 for jetting ink are formed using photolithography. Furthermore, a common supply channel 18 and a common recycling channel 19 are formed in the silicon substrate 310. Additionally, a supply connection channel 323 and a recycling connection channel 324 are formed in the silicon substrate 310; the common supply channel 18 and the pressure chambers 12 are interconnected via the supply connection channel 323, and the common recycling channel 19 and the pressure chambers 12 are interconnected via the recycling connection channel 324. In this embodiment, one jetting module 300 is configured to jet two types of ink. Specifically, in... Figure 3A Of the two injection modules 300 shown, the one located in Figure 3A The left-side inkjet 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, and any ink combination can be used. The 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 number of ink types. The configuration can include only one jetting module 300, or three or more jetting modules 300. Furthermore, in Figure 3A and Figure 3B In the example shown, two rows of nozzles extending in the Y direction are formed for ink of one color. Each of the plurality of nozzles 13 forming the rows of nozzles forms a pressure chamber 12, a common supply channel 18, and a common recovery channel 19.

[0048] The ink supply port and ink recycling 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 recovered from multiple common recovery channels 19 to ink recovery channel 49 through ink recovery port.

[0049] It should be noted that the ink supply port and ink recovery port correspond to the openings used for supplying and recovering ink during the forward ink circulation 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 recovered from the common recovery channel 19 into the ink recovery port. It should also be noted that an ink circulation in the opposite direction can also be performed. In this case, ink is supplied from the aforementioned ink recovery port into the common recovery channel 19, and ink is recovered from the common supply channel 18 into the ink supply port.

[0050] like Figure 3A As shown, the back 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 3A The ink supply channel 48 and the ink recovery 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 of the ink supply channel 48 on one side communicates with the aforementioned ink supply port in the silicon substrate 310. The opening of the ink recovery channel 49 on this side communicates with the aforementioned ink recovery port in the silicon substrate 310. It should be noted that the ink supply channel 48 and the ink recovery channel 49 are independently provided for each type of ink.

[0051] In addition, it has an opening 7a for inserting the injection module 300 (see Figure 3A The second support member 7 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 protect them from ink corrosion and external impacts.

[0052] Furthermore, the electrical contact substrate 6 is joined to the end 5a of the electrical wiring component 5 by thermoforming an anisotropic conductive film (not shown) (see [link]). 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 injection device 50.

[0053] In addition, a connecting member 8 is provided between the first support member 4 and the circulation unit 54. Figure 3AIn the connecting member 8, a supply port 88 and a return port 89 are formed for each type of ink. Through the supply port 88 and the return port 89, the ink supply channel 48 and the ink return 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 recycling port 89B are used for black ink, and supply port 88C and recycling port 89C are used for cyan ink. Additionally, supply port 88M and recycling port 89M are used for magenta ink, and supply port 88Y and recycling port 89Y are used for yellow ink.

[0054] It should be noted that the openings at one end of the ink supply channel 48 and the ink recovery channel 49 in the first support member 4 have small opening areas that match the ink supply port and ink recovery 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 recovery channel 49 in the first support member 4 have an enlarged shape, and their opening areas are the same as the opening areas formed in the connecting member 8 so as to match the channels in the circulation unit 54. This configuration can suppress the increase in channel resistance of the ink recovered from each recovery channel. It should be noted that the shapes of the openings at one end and the other end of the ink supply channel 48 and the ink recovery channel 49 are not limited to the examples described above.

[0055] In the liquid jet head 1 with the above configuration, 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. When 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 recovery connection channel 324 and the common recovery channel 19, and flows from the ink recovery port into the ink recovery channel 49 in the first support member 4. Then, the ink flowing into the ink recovery channel 49 flows into the circulation unit 54 through the recovery port 89 in the connecting member 8 and is recovered.

[0056] <Components of a Loop Unit>

[0057] Figure 4 This is a schematic diagram showing the external appearance of a circulation unit 54 for a type of ink used in the printing apparatus of this embodiment. A filter 110, a first pressure regulating unit 120, a second pressure regulating unit 150, and a circulation pump 500 are disposed in the circulation unit 54. Figure 5 and Figure 6 As shown, these components are connected by channels to form a circulation path for supplying ink to the jetting module 300 in the liquid jetting head 1 and for recovering ink from the jetting module 300.

[0058] <Circulation path in a liquid jet head>

[0059] Figure 5 A longitudinal cross-sectional view is shown schematically to illustrate the circulation path formed in the liquid jet head 1 for one type of ink (one color of ink). For a clearer depiction of the circulation path, a simplified view is provided. 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 21 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 6 As shown, the first pressure regulating unit 120 includes a first valve chamber 121 and a first pressure control chamber 122. The second pressure regulating unit 150 includes a second valve chamber 151 and a second pressure control chamber 152. The first pressure regulating unit 120 is configured such that the controlled pressure therein is higher than the controlled pressure in the second pressure regulating unit 150. In this embodiment, the two pressure regulating units 120 and 150 are used to achieve circulation within a certain pressure range within a circulation path. Furthermore, this configuration causes the 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. The following will refer to... Figure 5 and Figure 6 Describe the circulation path in liquid ejector 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.

[0060] First, we will describe how the constituent elements in the liquid jet head 1 are connected.

[0061] External pump 21 via ink supply tube 59 ( Figure 1A Connected to the circulation unit 54, the external pump 21 stores ink in the cartridge 2 located outside the liquid ejector head 1. Figure 6 The ink in the liquid is delivered to the liquid jet head 1. A filter 110 is disposed in the ink channel upstream of the circulation unit 54. The ink supply path downstream of the filter 110 is connected to the first valve chamber 121 of the first pressure regulating unit 120. The first valve chamber 121 is accessible by a pressure regulating unit 120. Figure 5 The valve 190A (first valve) shown has a connection port 191A (first connection port) that is open and closed, which is connected to the first pressure control chamber 122.

[0062] The first pressure control chamber 122 is connected to the supply channel 130, the bypass channel 160, and the pump outlet channel 180 of the circulation pump 500. The supply channel 130 is connected to the common supply channel 18 via the ink supply port provided in the ink jet 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 second valve 190B shown has a connection port 191B (second connection port) that connects to the second pressure control chamber 152. 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.

[0063] The second pressure control chamber 152 is connected to the recovery channel 140. The recovery channel 140 is connected to the common recovery channel 19 via the ink recovery port provided in the jetting 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 the pump inlet channel 170.

[0064] Next, the ink flow in the liquid ejector head 1 with the above configuration will be described. For example... Figure 6 As shown, the ink stored in the ink cartridge 2 is pressurized by the external pump 21 installed 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.

[0065] The ink supplied to the circulation unit 54 passes through the filter 110, thereby removing foreign matter such as dust and air bubbles. The ink then flows into the first valve chamber 121 located in the first pressure regulating unit 120. While the ink is passing through the filter 110, the ink pressure decreases due to pressure loss, but it remains positive. Subsequently, with valve 190A open, the ink flowing into the first valve chamber 121 passes through the connection port 191A and flows into the first pressure control chamber 122. Due to the pressure loss while the ink is passing through the connection port 191A, the pressure of the ink flowing into the first pressure control chamber 122 switches from positive to negative.

[0066] 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 below, 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.

[0067] 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 recovery channel 19. Thereafter, the ink flows into recovery channel 140 connected to jet module 300. Ink flowing into recovery channel 140 flows into second pressure control chamber 152 of second pressure regulating unit 150.

[0068] 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 recovered from the recovery 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 into the second pressure control chamber 152 from the first pressure control chamber 122 through the supply channel 130 and the jet 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 circulation is performed within the circulation path in this manner.

[0069] As described above, in this embodiment, the circulation pump 500 can be used to circulate the liquid through a corresponding circulation path formed in the liquid jet head 1. This allows for the suppression of ink thickening and the deposition of ink settling components such as pigments in the jet module 300. Therefore, excellent ink flowability and excellent jetting characteristics at the jet nozzle can be maintained in the jet module 300.

[0070] Furthermore, in this embodiment, the circulation path is configured to be completed within the liquid ejector head 1. Therefore, compared to the case where the ink circulates between the ink cartridge 2, which is located outside the liquid ejector head 1, and the liquid ejector head 1, the length of the circulation path is significantly shortened. Thus, the ink can be circulated using a small circulation pump.

[0071] Furthermore, this configuration allows for the inclusion of only a channel for supplying ink as a connection between the liquid ejector head 1 and the ink cartridge 2. In other words, the configuration does not require a channel for recovering ink from the liquid ejector head 1 back to the ink cartridge 2. Therefore, only an ink supply tube connecting the ink cartridge 2 and the liquid ejector head 1 is needed, and an ink recovery tube is not required. Consequently, the internal structure of the liquid ejector device 50 has a simpler configuration with fewer tubes. This enables overall device miniaturization. In addition, reducing the number of tubes reduces ink pressure fluctuations caused by tube oscillation during the main scan of the liquid ejector head 1. Furthermore, tube oscillation during the main scan of the liquid ejector head 1 increases the drive load on the carriage motor that drives the carriage 60. Therefore, reducing the number of tubes reduces the drive load on the carriage motor, thus simplifying the main scan mechanism, including the carriage motor and the like. Furthermore, since it is not necessary to recover ink from the liquid ejector head 1 back to the ink cartridge, miniaturization of the external pump 21 is also possible. As described above, according to this embodiment, miniaturization of the liquid ejector device 50 and cost reduction can be achieved.

[0072] <Pressure Regulation Unit>

[0073] Figures 7A to 7C A view illustrating an example of a pressure regulating unit. (Refer to...) Figures 7A to 7C The configuration and operation of the pressure regulating units (first pressure regulating unit 120 and second pressure regulating unit 150) placed in the liquid injection head 1 described above will be described in more detail. It should be noted that the first pressure regulating unit 120 and the second pressure regulating unit 150 have substantially the same configuration. 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 7C The figures only show the reference numerals for the parts corresponding to those of the first pressure regulating unit. 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.

[0074] 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 within 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 disposed in the first valve chamber 121 switches between allowing communication between the first valve chamber 121 and the first pressure control chamber 122 through the communication port 191 and preventing 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 the close contact with the partition 123. Note that the portion of the valve 190 that contacts the partition 123 is preferably formed of an elastic member to enhance the tightness of the contact with the partition 123. Furthermore, a valve shaft 190a, which is inserted through the connection port 191, is positioned in a protruding manner on the central portion of the valve 190. By pressing the valve shaft 190a to overcome the biasing force from the valve spring 200, the valve 190 separates from the partition 123, thereby allowing ink to flow through the connection port 191. In the following text, the state in which the valve 190 prevents ink from flowing 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."

[0075] The opening of the cylindrical housing 125 is closed by a flexible member 230 and a pressure plate 210. These flexible members 230, the 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 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 heat fusion.

[0076] A pressure adjusting spring 220 (bias unit) is disposed between the pressure plate 210 and the partition plate 123. For example... Figure 7AAs shown, the pressure plate 210 and the flexible member 230 are biased in the direction of increasing internal volume of the first pressure control chamber 122 by the biasing force from the pressure regulating spring 220. Furthermore, as the pressure in the first pressure control chamber 122 decreases, the pressure plate 210 and the flexible member 230 overcome the pressure from the pressure regulating spring 220 and shift 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, overcomes the biasing force from the valve spring 200 and thus separates from the partition 123. As a result, the communication port 191 switches to the open state. Figure 7B (State).

[0077] In this embodiment, the connection in the circulation path is configured such that the pressure in the first valve chamber 121 is higher than the pressure in the first pressure control chamber 122 when the connection port 191 is switched to the open state. In this way, 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 partition 123 by the biasing force from the valve spring 200, causing the connection port 191 to switch to the closed state. Figure 7C (State).

[0078] As described above, in the first pressure regulating unit 120 of this embodiment, when the pressure in the first pressure control chamber 122 drops below a certain pressure (for example, when the negative pressure increases), ink flows out 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.

[0079] As described above, the first pressure regulating unit 120 has a first pressure control chamber (first liquid chamber) 122 (which stores liquid supplied from the liquid supply source (cartridge 2) and the circulation pump 500) and a first regulating mechanism (which regulates the pressure of the liquid in the first pressure control chamber 122). Furthermore, the first regulating mechanism includes the aforementioned pressure plate 210, pressure regulating spring 220, valve 190, valve spring 200, and first valve chamber 121, and is configured to regulate the pressure of the liquid stored in the first pressure control chamber 122 according to the volume of the first pressure control chamber 122. Furthermore, the second pressure regulating unit 150 has a second pressure control chamber (second liquid chamber) 152 connected to the pump inlet passage 170, and a second regulating mechanism for regulating the pressure of the liquid stored in the second pressure control chamber 152. The second regulating mechanism includes the aforementioned pressure plate 210, pressure regulating spring 220, second valve 190B, second valve spring 200, and second valve chamber 151, and is configured to regulate the pressure of the liquid stored in the second pressure control chamber 152 according to the volume of the second pressure control chamber 152.

[0080] Next, the pressure in the first pressure control chamber 122 will be described in more detail.

[0081] Consider a state in which the flexible member 230 and the pressure plate 210 are displaced according to the pressure in the first pressure control chamber 122 as described above, 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 expressed by the following formula 1.

[0082] P2×S2+F2+(P1-P2)×S1+F1=0…Formula 1

[0083] Furthermore, Formula 1 for P2 is summarized as follows:

[0084] P2=-(F1+F2+P1×S1) / (S2-S1)…Formula 2

[0085] P1: Pressure (gauge pressure) in the first valve chamber 121

[0086] P2: Pressure (gauge pressure) in the first pressure control chamber 122

[0087] F1: Spring force of valve spring 200

[0088] F2: Spring force of pressure regulating spring 220

[0089] S1: Pressure-bearing area of ​​valve 190

[0090] S2: The pressure area of ​​pressure plate 210

[0091] Here, the spring force F1 of valve spring 200 and the spring force F2 of pressure regulating spring 220, the directions in which they push valve 190 and pressure plate 210 are defined as the forward direction. Figures 7A to 7C (to the left in the middle). In addition, this configuration 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.

[0092] When the connection port 191 is switched to the open state, the pressure P2 in the first pressure control chamber 122 is determined by Formula 2. Because this configuration 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 no longer decreases further and is maintained within a certain range.

[0093] On the other hand, such as Figure 7C As shown, when the pressure plate 210 does not abut against the valve shaft 190a and the communication port 191 is switched to the closed state, the relationship between the forces acting on the pressure plate 210 is expressed by the following formula 3.

[0094] P3×S3+F3=0…Formula 3

[0095] Here, Formula 3 is summarized for P3 as follows:

[0096] P3=-F3 / S3…Formula 4

[0097] F3: The spring force of the pressure regulating spring 220 when the pressure plate 210 is not in contact with the valve shaft 190a.

[0098] P3: Pressure (gauge pressure) in the first pressure control chamber 122 when the pressure plate 210 is not in contact with the valve shaft 190a.

[0099] S3: The pressure area of ​​the pressure plate 210 when it is not in contact with the valve shaft 190a.

[0100] 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 adjusting spring 220, and the pressure-bearing area S3 of the pressure plate 210 are adjusted according to the pressure plate 210 and the flexible member 230. Figure 7C The amount of displacement varies depending on the state shift. Specifically, the pressure plate 210 and the flexible member 230 relative to the state shift... Figure 7C The ones shown are located in Figure 7CWhen the pressure is slightly to the right, the pressure-bearing area S3 of the pressure plate 210 decreases, and the spring force F3 of the pressure regulating spring 220 increases. Therefore, according to the relationship in Formula 4, the pressure P3 in the first pressure control chamber 122 decreases. Thus, according to Formulas 2 and 4, when... Figure 7B State transition to Figure 7C When the pressure plate 210 and flexible member 230 are in the open state from the communication port 191, they gradually shift to the left until the internal volume of the first pressure control chamber reaches the limit of their displacement. In other words, the negative pressure decreases.

[0101] <Circulation Pump>

[0102] Next, we will refer to Figure 8A , Figure 8B and Figure 9 The configuration and operation of each circulation pump 500 located in the liquid injection head 1 described above are explained in detail.

[0103] 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 8B This 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 bonded 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 this pair of through holes, located at one location, forms a pump supply hole 501. The other through hole in this pair of through holes, located at the other location, forms a pump discharge hole 502. The pump supply hole 501 is connected to a pump inlet passage 170 connected to a second pressure control chamber 152. The pump discharge hole 502 is connected to a pump outlet passage 180 connected to a first pressure control chamber 122. Ink supplied from the pump supply hole 501 passes through a pump chamber 503, described later (see [link to relevant documentation]). Figure 9 And it is discharged from the pump discharge port 502.

[0104] Figure 9 for Figure 8AThe 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 provided at the middle portion of the pump supply port 501. A check valve 504b is provided at the middle portion of the pump discharge port 502. Specifically, the check valve 504a is configured such that a portion thereof can extend within the space 512a formed in the middle portion of the pump supply port 501. Figure 9 The check valve 504b is configured such that a portion of it can move to the left within the space 512b formed in the middle portion of the pump discharge port 502. Figure 9 Move to the right in the middle.

[0105] When 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 along the middle). 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. When the diaphragm 506 shifts to reduce the volume of the pump chamber 503, the pump chamber 503 is pressurized. 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. Thus, the check valve 504a is in a closed state that prevents ink from flowing through the pump supply port 501.

[0106] 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 where 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 (Moves to the right along the middle), thereby allowing ink to flow through the pump discharge hole 502.

[0107] It should be noted that the materials of each check valve 504a and 504b must be materials that can deform under the pressure in the pump chamber 503. For example, the materials of each check valve 504a and 504b can be made of elastic materials, such as ethylene-propylene-diene terpolymer (EPDM) or elastomers, or polypropylene membranes or sheets, etc. However, the materials are not limited to these.

[0108] 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 pump chamber 503 is reduced in volume due to a rightward shift (in the pump chamber 503), the pressure in the pump chamber 503 increases. As a result, the check valve 504b, which is positioned facing the pump discharge port 502, switches to the open state, allowing ink to be discharged from the pump chamber 503. At this time, the check valve 504a, which is positioned facing the pump supply port 501, comes into close contact with the wall surrounding the pump supply port 501, thereby preventing ink from flowing back from the pump chamber 503 into the pump supply port 501.

[0109] Conversely, as the diaphragm 506 shifts along the widening direction of 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 to close the opening. This prevents ink from flowing back from the pump discharge port 502 into the pump chamber 503.

[0110] 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 due to the expansion or contraction of the bubbles slightly alters the pressure in the pump chamber 503. Therefore, the liquid delivery rate decreases. To address this phenomenon, the pump chamber 503 is positioned 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 of air bubble discharge from the pump, thereby stabilizing the flow rate.

[0111] Now, refer to Figure 10A , Figure 10B and Figure 11 Describe the specific configuration of the components of the circulating pump 500. Figure 10A and Figure 10B This is an exploded perspective view of the Circulating Pump 500. Figure 10A This is an exploded perspective view of the various components of the circulation pump 500 as seen from the rear. Figure 10B This is an exploded perspective view of the various components of the circulation pump 500, viewed from the front. The circulation pump 500 in this embodiment is a piezoelectric pump driven by applying a voltage to its piezoelectric ceramic. Figure 10A and 10BAs shown, a circular vibrating plate 509 is bonded to a diaphragm 506 using adhesive material 508. A circular piezoelectric ceramic 510 is bonded and fixed to the vibrating plate 509. The diaphragm 506 is made of an injection-moldable material, such as modified polyphenylene oxide (PPE+PS) or polypropylene. Alternatively, a component stamped from a membrane or resin sheet can be used. The material is not limited to these. The vibrating plate 509 is made of brass, stainless steel, iron-nickel alloy, etc., but the material is not limited to these.

[0112] A drive circuit board 513 is disposed on the surface opposite to the piezoelectric ceramic 510. The drive circuit board 513 is connected to a power supply unit disposed in the main body of the liquid jetting device 50, and applies a predetermined drive voltage (AC voltage) to the piezoelectric ceramic 510 and the vibrating plate 509.

[0113] Figure 11 This is a view of the electrical connection portion of the piezoelectric ceramic 510 as seen through the drive circuit board 513 from the cover 507 side. The drive circuit board 513 and the piezoelectric ceramic 510 are connected by an electrical connection cable 518a, and the drive circuit board 513 and the vibrating plate 509 are connected by an electrical connection cable 518b. Solder joint 520 electrically connects the electrical connection cable 518a to the drive circuit board 513, and also electrically connects the electrical connection cable 518b to the drive circuit board 513. Solder joint 521 electrically connects the electrical connection cable 518a to the piezoelectric ceramic 510, and also electrically connects the electrical connection cable 518b to the vibrating plate 509.

[0114] The vibrating plate 509 is connected to the GND wiring of the drive circuit board 513 via an electrical connection cable 518b. The piezoelectric ceramic 510 is connected to the AC voltage output unit of the drive circuit board 513 via an electrical connection cable 518a. By connecting the vibrating plate 509 to GND and applying an AC voltage with a phase difference to the piezoelectric ceramic 510, the piezoelectric ceramic 510 is stretched and contracted to deform the diaphragm. In this way, the pressure in the pump chamber is changed to draw in or expel ink.

[0115] The drive circuit board 513 is electrically connected to the electrical contact substrate 6 via a cable, and the electrical contact substrate 6 is provided with electrical connection terminals for driving the pump. When the circulation unit 54 is attached to the carriage 60, the electrical signal output from the electrical contact portion (not shown, first electrical connection portion) on the carriage 60 side is input to the drive circuit board 513 through the corresponding electrical connection terminal (not shown, second electrical connection portion) on the electrical contact substrate 6.

[0116] As described above, by providing electrical connection terminals for driving the pump on the electrical contact substrate 6, the circulating pump 500 can be driven by applying a driving voltage (AC voltage) to the corresponding electrical connection terminals even when it is detached from the carriage 60.

[0117] <Ink flow inside the liquid ejector head>

[0118] Figures 12A to 12E This is a diagram illustrating the ink flow inside a liquid ejector head. (Refer to...) Figures 12A to 12E 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 12A to 12E 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 considered. Therefore, the relative positions of these components differ from those of the components in the system. Figure 2 and Figure 4 And what will be mentioned later Figure 21 and Figure 22 The relative positions of the components. Figure 12A The diagram schematically illustrates the ink flow during a printing operation (performed by ejecting ink from nozzle 13). Note that... Figure 12A The arrows indicate the flow of ink. In this embodiment, both the external pump 21 and the circulation pump 500 are started to drive in order to perform a printing operation. Incidentally, the external pump 21 and the circulation pump 500 can be driven 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 in conjunction with each other, but can be driven independently of each other.

[0119] During printing, the circulation pump 500 is in the on (driven) state, causing ink flowing from the first pressure control chamber 122 (first liquid chamber) to flow into the supply channel 130 and the bypass channel 160. Ink that has flowed into the supply channel 130 passes through the jetting module 300 and then flows into the recovery channel 140. Thereafter, ink is supplied to the second pressure control chamber 152.

[0120] 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 Formula 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 jetting module 300 through the supply channel 130. The ink flowing into the jetting module 300 flows back into the first pressure control chamber 122 through the recovery 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 jetting head 1 is performed as described above.

[0121] In the ink circulation described above, 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 jet module 300. Furthermore, this pressure difference is set to obtain a circulation volume capable of suppressing ink thickening near the jet nozzle in the jet module 300. Incidentally, the amount of ink consumed by printing is supplied from the ink cartridge 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 decreases due to the amount of ink consumed by printing. Therefore, the pressure in the first pressure control chamber 122 decreases, resulting in a decrease 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 the internal volume of the first pressure control chamber 122 decreases below a predetermined volume, the connection port 191A (first connection port) switches to an 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 of 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 above a predetermined volume, the connection port 191A switches to a closed state. As described above, the connection port 191A repeatedly switches between an open state and a closed state based on ink consumption. Incidentally, when no ink is consumed, the connection port 191A remains in the closed state.

[0122] Figure 12B The diagram schematically illustrates the ink flow immediately following the completion of the printing operation and the switching of the circulation pump 500 to the off state (stopped state). When the printing operation is complete 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 during 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 flows as follows... Figure 12B The movement is as shown. Specifically, an ink flow is continuously generated from the first pressure control chamber 122 through the supply channel 130 to the jet module 300 and then through the recovery channel 140 to the second pressure control chamber 152. In addition, an ink flow is continuously 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.

[0123] The amount of ink flowing from the first pressure control chamber 122 to the second pressure control chamber 152 via these ink flows is supplied from the ink cartridge 2 through the filter 110 and the first valve chamber 121 to the first pressure control chamber 122. Therefore, the internal volume of the first pressure control chamber 122 remains constant. According to the relationship in Formula 2 above, with the internal volume of the first pressure control chamber 122 constant, the spring force F1 of the valve spring 200, the spring force F2 of the pressure regulating spring 220 (bias unit), the pressure-bearing area S1 of the valve 190, and the pressure-bearing 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. In this way, with the pressure P1 in the first valve chamber 121 unchanged, the pressure P2 in the first pressure control chamber 122 is maintained at the same pressure as the controlled pressure during printing operation.

[0124] 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 flowing in from the first pressure control chamber 122. Specifically, the pressure in the second pressure control chamber 152 changes according to Formula 2 until the connecting port 191 discharges ink from the ink inlet. Figure 12B The state is switched to the closed state to allow no communication between the second valve chamber 151 and the second pressure control chamber 152 (e.g.) Figure 12C (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 12D As shown, ink flows from the recovery channel 140 into the second pressure control chamber 152. This ink inflow causes the pressure plate 210 and the flexible member 230 to shift. The pressure in the second pressure control chamber 152 varies according to Formula 4. Specifically, the pressure increases until the internal volume of the second pressure control chamber 152 reaches its maximum value.

[0125] Note that once it reaches... Figure 12C In 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 via the recovery channel 140 can only occur after the ink in the first pressure control chamber 122 has been 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 according to the pressure difference between the pressure in the first pressure control chamber 122 and the pressure in the second pressure control chamber 152. Therefore, when the pressure in the second pressure control chamber 152 becomes equal to the pressure in the first pressure control chamber 122, the ink movement stops.

[0126] 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 12D The state shown. In the case of... Figure 12D When the second pressure control chamber 152 expands, a storage section capable of holding ink is formed within it. Note that this is achieved after stopping the circulation pump 500. Figure 12D The time required for this process is approximately 1 to 2 minutes. This time can vary depending on the shape and size of the channel and the nature of the ink. Figure 12D 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 12E 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 12A The state shown.

[0127] In this embodiment, during the liquid circulation operation described above, the characteristic pressure relationship represented by the following inequalities 5 and 6 is maintained.

[0128] P22>P21…Formula 5

[0129] P21: Pressure (gauge pressure) in the first pressure control chamber 122 when the circulating pump 500 stops.

[0130] P22: Pressure (gauge pressure) in the first pressure control chamber 122 when the circulating pump 500 is driven.

[0131] Furthermore, when the circulating pump 500 is driven, the pressure in the first pressure control chamber 122 is reduced, but the following formula is satisfied.

[0132] P22-ΔP<0…Formula 6

[0133] ΔP: Pressure loss from the first pressure control chamber 122 to the pressure chamber 12 when the circulating pump is driven.

[0134] By meeting the above conditions, ink leakage from the nozzle 13 can be prevented while the circulation pump 500 is driven.

[0135] Using the above configuration, the ink circulates through a circulation path completed within the liquid ejector head 1. Therefore, even if ink concentration or pigment sedimentation temporarily occurs in the pressure chamber 12, the circulation of the ink through the circulation path quickly resolves the problems of pigment sedimentation and liquid thickening. This reduces downtime during printing.

[0136] Furthermore, in this embodiment, the configuration places the filter 110 outside the ink circulation path, and once the ink passes through the filter 110, it circulates through the circulation path without passing through the filter again. This prevents the filter 110 from becoming clogged by clumps or other contaminants in the ink due to repeated ink circulation. Additionally, a relatively short circulation path is formed within the liquid ejector head 1. Moreover, placing the filter outside the circulation path reduces pressure loss within the circulation path. This allows circulation to be performed using the relatively small circulation pump 500 described in this embodiment. Furthermore, the pressure of the liquid supplied from the external pump through the filter 110 can be appropriately controlled by the first pressure regulating unit 120 on the supply channel 130. This allows ink to be supplied to the filter 110 by pressurizing it with an external pump. Therefore, the filter area can be set to be small, and the liquid ejector head can be miniaturized.

[0137] Furthermore, in this embodiment, such as Figures 12A to 12E As shown, the filter surface of filter 110 is arranged along the direction of gravity, more preferably parallel to the direction of gravity, and the inlet and outlet channels 270 and 290 of filter 110 are provided in the lower part of the filter. This facilitates the flow of settled pigment downstream. Therefore, clogging of filter 110 can be prevented.

[0138] Furthermore, in the first pressure control chamber 122 and the second pressure control chamber 152, liquid outlets 250 and 240 are located in the lower part of the pressure control chamber (the portion of the pressure control chamber below its middle section in the direction of gravity) along the direction of gravity, and the liquid stored in the respective pressure control chambers 122 and 152 is discharged through the liquid outlets 250 and 240. In this way, even if ink components have settled, these settled substances are more easily discharged from the pressure control chambers 122 and 152. This shortens the time required for ink agitation through circulation.

[0139] Incidentally, when using inks with pigments that settle at high speeds (e.g., white ink), it is necessary to agitate the ink by performing circulation even when printing is not performed. However, in this embodiment, the ink can circulate within the liquid jet head 1 even when the circulation unit 54 is not mounted on the main body unit (e.g., carriage) of the liquid jet device 50. That is, even when the liquid jet head 1 is detached from the carriage 60 mounted on the main body of the liquid jet device 50, the circulation pump 500 can be driven by applying AC voltage to the electrical connection terminals of the electrical contact substrate 6, thereby enabling ink circulation. In this way, the pigment settling problem within the liquid jet head 1 can be resolved in advance before use, thereby efficiently initiating the printing operation. Furthermore, when ink circulation is performed when the liquid jet head 1 is not mounted on the main body of the liquid jet device, power consumption is reduced compared to when circulation is performed when the liquid jet head 1 is mounted on the main body of the liquid jet device.

[0140] It should be noted that in the description above, Figure 12A This has already 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, the ink will circulate in response to the driving and stopping of the circulation pump 500. Figures 12A to 12E The flow is shown.

[0141] 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 explained in detail below along with the function of the bypass channel 160.

[0142] The purpose of providing the bypass channel 160 between the first pressure regulating unit 120 and the second pressure regulating unit 150 is to enable the jetting module 300 to avoid the effects of strong negative pressure, for example, if the negative pressure generated within the circulation path becomes stronger than a preset value. The purpose of providing the bypass channel 160 is also to supply ink to the pressure chamber 12 from the supply channel 130 and the recovery channel 140.

[0143] First, an example will be explained to prevent negative pressure that becomes stronger than a preset value from affecting the jetting module 300 by setting a bypass channel 160. For example, changes in ambient temperature can sometimes alter the properties of ink (e.g., viscosity). As ink viscosity changes, the pressure loss within the circulation path also changes. For example, as 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 jetting module 300 increases. Here, the jetting module 300 is maintained at a constant temperature by a temperature regulating mechanism (not shown). Therefore, even if the ambient temperature changes, the ink viscosity inside the jetting module 300 remains constant. Since the ink viscosity inside the jetting module 300 remains constant, while the flow rate of the ink flowing through the jetting module 300 increases, the negative pressure in the jetting module 300 correspondingly increases due to flow resistance. If the negative pressure in the jetting module 300 becomes stronger than the preset value described above, there is a possibility that the meniscus in the jetting 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 crescent does not rupture, there is still a possibility that the negative pressure in pressure chamber 12 could become stronger than the predetermined level and affect the jetting.

[0144] Therefore, 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. Thus, the pressure in the ejection module 300 remains constant. Therefore, for example, the controlled pressure can be set such that even when the circulation pump 500 is driven, the connection port 191B in the second pressure regulating unit 150 remains closed. Furthermore, the controlled pressure in the second pressure regulating unit 150 can be set such that when the negative pressure becomes stronger than a preset value, the connection port 191B in the second pressure regulating unit 150 switches to an open state. In other words, when the circulation pump 500 is driven, even if the pump flow rate changes due to viscosity changes caused by environmental changes, the connection port 191B can remain closed as long as the meniscus does not collapse or the predetermined negative pressure is maintained.

[0145] Next, an example of setting up a bypass channel 160 to supply ink to the pressure chamber 12 from the supply channel 130 and the recovery channel 140 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.

[0146] The following will explain that, in the case of continuous high duty cycle printing, the ink to be supplied to pressure chamber 12 is supplied from both the supply channel 130 side and the return channel 140 side. Although the definition of "duty cycle" can vary depending on various conditions, in the following text, the state of printing 1200 dpi grid cells with a single 4pl ink droplet will be considered 100%. "High duty cycle printing" refers to printing performed, for example, at a 100% duty cycle.

[0147] During continuous high duty cycle printing, the amount of ink flowing from pressure chamber 12 into the second pressure control chamber 152 through recovery 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 the second pressure control chamber 152. Consequently, the amount of ink in the second pressure control chamber 152 decreases, and the negative pressure in the second pressure control chamber 152 becomes stronger, causing the second pressure control chamber 152 to contract. As the negative pressure in the second pressure control chamber 152 becomes stronger, the amount of ink flowing into the second pressure control chamber 152 through bypass channel 160 increases, and the second pressure control chamber 152 stabilizes in a state of balance between inflow and outflow. Therefore, the negative pressure in the second pressure control chamber 152 becomes stronger according to the duty cycle. Furthermore, as described above, in a configuration where the connection port 191B is closed when circulation pump 500 is driven, the connection port 191B switches to an open state according to the duty cycle, causing ink to flow into the second pressure control chamber 152 from bypass channel 160.

[0148] Furthermore, as high duty cycle printing continues, the inflow from pressure chamber 12 into the second pressure control chamber 152 via recovery channel 140 decreases, while the inflow from connector 191B into the second pressure control chamber 152 via bypass channel 160 increases. As this state progresses, the amount of ink flowing from pressure chamber 12 into the second pressure control chamber 152 via recovery channel 140 reaches zero, such that the ink flowing out of connector 191B is all the ink that has flowed into circulation pump 500. As this state progresses further, ink flows back from the second pressure control chamber 152 into pressure chamber 12 via recovery channel 140. In this state, ink flowing from the second pressure control chamber 152 into circulation pump 500 and ink flowing from the second pressure control chamber 152 into pressure chamber 12 will flow from connector 191B into the second pressure control chamber 152 via bypass channel 160. In this case, ink from supply channel 130 and ink from recycling channel 140 are filled into pressure chamber 12 and ejected from pressure chamber 12.

[0149] It should be noted that the ink backflow occurring at high print duty cycles is due to the installation of the bypass channel 160. Furthermore, as described above, an example has been given of the connection port 191B in the second pressure regulating unit being switched to the open state for ink backflow. However, ink backflow may also occur even when the connection port 191B in the second pressure regulating unit is in the open state. Moreover, in a configuration without the second pressure regulating unit, the aforementioned ink backflow may also occur due to the installation of the bypass channel 160.

[0150] <Configuration of the injection unit>

[0151] Figure 13A and 13B This is a schematic diagram illustrating the circulation path of ink of one color in the injection unit 3 of this embodiment. Figure 13A This is an exploded perspective view of the injection unit 3 as seen from the side of the first support member 4. Figure 13B This is an exploded perspective view of the injection unit 3 as seen from the side of the injection module 300. Note that... Figure 13A and 13B The arrows labeled "IN" and "OUT" indicate ink flow, and the description only refers to one color; however, other colors flow similarly. Furthermore, in... Figure 13A and 13B 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 injection unit configuration. Furthermore, for Figure 13A The first support member 4 in the middle is shown along Figure 3A The cross-section of line XIII-XIII in the middle. Each spray module 300 includes a spray element substrate 340 and an opening plate 330. Figure 14 This is a view showing the opening plate 330. Figure 15 This is a view showing the jetting element substrate 340.

[0152] From each circulation unit 54 via the connecting member 8 (see...) Figure 3A Ink is supplied to the injection unit 3. The ink path of the ink returning to the coupling member 8 after passing through the coupling member 8 will now be described. Note that the coupling member 8 is omitted from the figures mentioned below.

[0153] Each ejection module 300 includes an ejection element substrate 340 and an opening plate 330 (which are silicon substrates 310), and also includes an outlet forming member 320. The ejection element substrate 340, the opening plate 330, and the outlet forming member 320 are stacked and joined to communicate the respective ink channels with each other to form the ejection module 300. The ejection module 300 is supported on a first support member 4. An ejection unit 3 is formed by supporting the respective ejection modules 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 multiple rows of outlets, each row of outlets being a plurality of outlets 13 arranged in 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 recovered through the ink channels in the ejection module 300.

[0154] like Figure 13A and Figure 13B as well as Figure 14 As shown, the opening plate 330 includes multiple rows of ink supply ports 311 and multiple rows of ink return ports 312. (As...) Figure 15 and Figures 16A to 16C As shown, the jetting element substrate 340 includes multiple rows of supply connection channels 323 and multiple rows of recycling connection channels 324. The jetting element substrate 340 also includes a common supply channel 18 communicating with the multiple supply connection channels 323 and a common recycling channel 19 communicating with the multiple recycling connection channels 324. The ink supply channel 48 and ink recycling channel 49 are disposed in the first support member 4 (see...). Figure 3A The support member supply port 211 is a cross-sectional opening that forms the ink supply channel 48. The support member recovery port 212 is a cross-sectional opening that forms the ink recovery channel 49.

[0155] From loop unit 54 (see Figure 3A The ink supply channel 48 in the first lateral support member 4 (see) Figure 3A The ink to be supplied to the jetting unit 3. 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 is supplied through the ink supply port 311 in the opening plate 330 to the common supply channel 18 in the jet element substrate 340, and then into 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 recycling connection channel 324 of the recycling side channel. Details of the ink flow in the pressure chamber 12 will be described below.

[0156] In the recycling side channel, ink entering the recycling connection channel 324 flows into the common recycling channel 19. Thereafter, ink flows from the common recycling channel 19 through the ink recycling port 312 in the opening plate 330 into the ink recycling channel 49 in the first support member 4, and is recycled into the circulation unit 54 through the support member recycling port 212.

[0157] The area of ​​the opening plate 330 where neither the ink supply port 311 nor the ink return port 312 exists corresponds to the area of ​​the first support member 4 used to separate the support member supply port 211 and the support member return port 212. Furthermore, the first support member 4 has no openings in these areas. In the case of the adhesive jetting module 300 and the first support member 4, such areas serve as adhesive bonding areas.

[0158] exist Figure 14 In this configuration, multiple rows of openings arranged along the X direction are arranged side-by-side in the opening plate 330 along the Y direction, and openings for supply (input) and openings for recovery (output) are arranged alternately in the Y direction and simultaneously offset from each other by half a pitch in the X direction. Figure 15 In the jetting element substrate 340, a common supply channel 18 communicating with a plurality of supply connection channels 323 arranged along the Y direction and a common recycling channel 19 communicating with a plurality of recycling connection channels 324 arranged along the Y direction are alternately arranged in the X direction. The common supply channel 18 and the common recycling channel 19 are distinguished by ink type. Furthermore, the number of jetting nozzle arrays for each color determines the number of common supply channels 18 and common recycling channels 19 to be provided. Additionally, the number of supply connection channels 323 and the number of recycling connection channels 324 correspond to the number of jetting nozzles 13. It should be noted that a one-to-one correspondence is not required, and a single supply connection channel 323 and a single recycling connection channel 324 can correspond to multiple jetting nozzles 13.

[0159] Each jetting module 300 is formed by stacking and joining the aforementioned opening plate 330 and jetting element substrate 340 to allow the individual ink channels to communicate with each other and to be supported on the first support member 4. As a result, an ink channel including the supply channel and the recovery channel as described above is formed.

[0160] Figures 16A to 16C A cross-sectional view showing the ink flow at different parts of the jetting unit 3. Figure 16A It is along Figure 13A The image shows a cross-section taken by line XVIA-XVIA, ​​and also shows a cross-section of a portion of the jetting unit 3 in which the ink supply channel 48 and the ink supply port 311 are connected to each other. Figure 16B It is along Figure 13AThe image shows a cross-section taken by line XVIB-XVIB, and also shows a cross-section of a portion of the jetting unit 3, in which the ink recovery channel 49 and the ink recovery port 312 are connected to each other. Furthermore, Figure 16C It is along Figure 13A The cross-section is shown by line XVIC-XVIC, and the cross-section of the portion of ink supply port 311 and ink return port 312 that is not connected to the channel in the first support member 4 is also shown.

[0161] like Figure 16A As shown, ink is supplied from the overlapping and communicating portions of the ink supply channel 48 in the first support member 4 and the ink supply port 311 in the opening plate 330. Furthermore, as... Figure 16B As shown, the ink recovery channel recovers ink from the overlapping and communicating portions of the ink recovery channel 49 in the first support member 4 and the ink recovery port 312 in the opening plate 330. Furthermore, as... Figure 16C As shown, the jetting unit 3 partially has areas where no openings are provided in the opening plate 330. In these areas, neither ink is supplied nor recycled between the jetting element substrate 340 and the first support member 4. Figure 16A As shown, ink is supplied to the area where the ink supply port 311 is located. Figure 16B As shown, ink is recovered in the area where the ink recovery port 312 is provided. It should be noted that this embodiment has been described using a configuration with the opening plate 330 as an example, but a configuration without the opening plate 330 can also be used. For example, a configuration can be used where channels corresponding to the ink supply channel 48 and the ink recovery channel 49 are formed in the first support member 4, and the jetting element substrate 340 is attached to the first support member 4.

[0162] Figure 17A and Figure 17B This is a cross-sectional view showing the area near the injection port 13 in the injection module 300. Figure 18A and 18B 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 recovery channel 19 are widened in the X direction. Note that... Figure 17A and 17B as well as Figure 18A and 18BThe thick arrows shown in the common supply channel 18 and common recovery channel 19 indicate the oscillating motion of the ink that occurs in the configuration using the serial 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 jetting nozzle 13. When the jetting element 15 is not driven, the ink is recovered from the pressure chamber 12 through the recovery connection channel 324, which serves as a recovery channel, into the common recovery channel 19.

[0163] When using the serial liquid jetting device 50 to jet ink that is circulated as described above, the ink jetting is largely affected by the oscillating motion of the ink within the ink channel caused by the main scan 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 18A and 18B As shown, when the shared supply channel 18 and shared return channel 19 have a wider cross-sectional shape in the X direction, which is the main scanning direction, the ink within the shared supply channel 18 and shared return channel 19 is more susceptible to inertial forces in the main scanning direction, causing significant ink oscillation. This oscillating motion of the ink can affect the likelihood of ink being ejected from the ejection nozzle 13. Furthermore, widening the shared supply channel 18 and shared return channel 19 in the X direction increases the distance between colors. This may reduce printing efficiency.

[0164] Therefore, in this embodiment, each common supply channel 18 and each common recycling channel 19 (whose cross-section is as shown) Figure 17A and 17B (As shown) the configuration is such that each common supply channel 18 and each common return channel 19 extends along the Y direction and also along the Z direction, the Z direction being perpendicular to the X direction (i.e., the main scanning direction). With this configuration, the channel width of the common supply channel 18 and the common return channel 19 in the main scanning direction is reduced. By reducing the channel width of the common supply channel 18 and the common return channel 19 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 17A and 17B The oscillating motion of the ink within the shared supply channel 18 and shared return channel 19 (as indicated by the thick black arrow in the image) is reduced. This decreases the impact of ink oscillation on ink ejection. Furthermore, by extending the shared supply channel 18 and shared return channel 19 in the Z direction, their cross-sectional area is increased. This reduces the pressure drop across the channels.

[0165] As described above, each common supply channel 18 and each common return channel 19 has a reduced channel width in the main scanning direction. This configuration reduces the oscillating motion of ink within the common supply channel 18 and common return channel 19 during the main scan, but does not eliminate the oscillating motion. Therefore, in order to reduce the jetting differences between various ink types that may be caused by the reduced oscillating motion, the configuration in this embodiment is such that the common supply channel 18 and common return channel 19 are positioned to overlap each other in the X direction.

[0166] As described above, in this embodiment, the supply connection channel 323 and the recovery connection channel 324 are configured to correspond to the ejection port 13. Furthermore, the correspondence between the supply connection channel 323 and the recovery connection channel 324 is established such that the supply connection channel 323 and the recovery connection channel 324 are arranged in the X direction, with the ejection port 13 located between them. Therefore, if the shared supply channel 18 and the shared recovery 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 recovery connection channel 324 in the X direction is disrupted. Such inconsistency affects the flow of ink in the pressure chamber 12 in the X direction and ink ejection. If such inconsistency is combined with the effect of the oscillating motion of the ink, it may further affect the ink ejection of the individual ejection ports.

[0167] Therefore, by arranging the common supply channel 18 and the common recovery channel 19 at positions that overlap each other along the X direction, the oscillating motion of the ink within the common supply channel 18 and the common recovery channel 19 during the main scan is substantially the same at any position along the Y direction of the arrangement of the ejection nozzles 13. Consequently, the pressure difference generated in the pressure chamber 12 between the common supply channel 18 side and the common recovery channel 19 side does not change significantly. These low pressure differences enable stable ejection.

[0168] Furthermore, some liquid ejector heads in which ink circulates are configured such that the channel for supplying ink to the liquid ejector head and the channel for recovering ink are the same channel. However, in this embodiment, the common supply channel 18 and the common recovery 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 recovery 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 pressure chamber 12 (which serves as the path connecting the supply connection channel 323 and the recovery connection channel 324) is configured to include the ejection port 13. Therefore, an ink flow from the supply connection channel 323 side to the recovery connection channel 324 side is generated in each pressure chamber 12, and the ink within the pressure chamber 12 circulates efficiently. By efficiently circulating the ink within the pressure chamber 12, the ink within the pressure chamber 12, which is susceptible to ink evaporation from the ejection port 13, can be kept fresh.

[0169] Furthermore, since both channels (i.e., the common supply channel 18 and the common recovery channel 19) are connected to the pressure chamber 12, ink can be supplied from both channels when high-flow-rate jetting is required. In other words, compared to a configuration that forms only a single channel for ink supply and ink recovery, the configuration in this embodiment has the advantage of not only performing efficient cycles but also being able to handle high-flow-rate jetting.

[0170] Incidentally, when the shared supply channel 18 and the shared recycling channel 19 are positioned close to each other along the X direction, the impact of ink oscillation is minimized. Ideally, the shared supply channel 18 and the shared recycling channel 19 are configured such that the gap between the channels is 75 μm to 100 μm.

[0171] Figure 19 This is a view of the jetting element substrate 340, used as a comparative example. Note that in... Figure 19 The supply connection channel 323 and the recovery connection channel 324 are not shown in the diagram. Ink that has received heat energy from the jetting element 15 in the pressure chamber 12 flows into the common recovery channel 19. Therefore, the temperature of the ink flowing through the common recovery channel 19 is higher than the temperature of the ink in the common supply channel 18. Here, in the comparative example, only the common recovery channel 19 exists at a portion of the jetting element substrate 340 along the X direction, as shown... Figure 19 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.

[0172] The ink temperature flowing through the common supply channel 18 is lower than the ink temperature in the common recycling channel 19. Therefore, if the common supply channel 18 and the common recycling channel 19 are close to each other, the ink in the relatively cooler common supply channel 18 will lower the ink temperature in the common recycling channel 19 at the point where the two channels are close together. This suppresses temperature rise. For this purpose, it is preferable that the common supply channel 18 and the common recycling channel 19 have substantially the same length, exist at a position where they overlap each other along the X direction, and are close to each other.

[0173] Figure 20A and 20B This is a view showing the channel configuration of a liquid ejector head 1 for three colors of ink: cyan (C), magenta (M), and yellow (Y). In the liquid ejector head 1, as... Figure 20A As shown, circulation channels are provided for each ink type. Pressure chamber 12 is positioned along the X-direction, which is the main scanning direction of the liquid ejector head 1. Furthermore, as... Figure 20B As shown, a common supply channel 18 and a common recovery channel 19 are arranged along the nozzle array (i.e., the array of nozzles 13). The common supply channel 18 and the common recovery channel 19 are arranged to extend in the Y direction and the nozzle array is located between them.

[0174] <Connection between the main unit and the liquid injection head>

[0175] Figure 21 This is a schematic configuration diagram showing more specifically the connection state of the ink cartridge 2 and the external pump 21 (which are configured as the main body unit of the liquid ejection device 50 in this embodiment) with the liquid ejection head 1, as well as the arrangement of the circulation pump 500, etc. The configuration of the liquid ejection device 50 in this embodiment allows for simple replacement of only the liquid ejection head 1 in the event of a malfunction. Specifically, the liquid ejection device 50 in this embodiment has a liquid connection 700, in which each ink supply pipe 59 connected to the corresponding external pump 21 can be easily connected and disconnected from the liquid ejection head 1. Specifically, the liquid ejection device 50 in this embodiment has a liquid connection 700, through which each ink supply pipe 59 is connected to the corresponding external pump 21, and the liquid ejection heads 1 can be easily connected and disconnected from each other. This allows only the liquid ejection head 1 to be easily attached to and removed from the liquid ejection device 50.

[0176] like Figure 21As 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 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 cartridge 2 to the liquid ejector head 1 by pressurization.

[0177] As mentioned above, Figure 21 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, in the event of a degradation in the sealing performance between the liquid connector insertion slot 53a and the liquid connector 59a, ink supplied under pressure by the external pump 21 may leak from the liquid connection portion 700. For example, if the leaked ink adheres to the circulation pump 500, it may cause a malfunction in the electrical system. To address this issue, in this embodiment, the circulation pump, etc., is provided as described below.

[0178] Arrangement of circulating pumps, etc.

[0179] In this embodiment, as Figure 21 As shown, 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 direction of gravity. Specifically, the circulation pump 500 is positioned higher than the liquid connector insertion slot 53a (i.e., the liquid inlet in the liquid jet head 1) in the direction of gravity. Furthermore, the circulation pump 500 is positioned at a location that does not contact the components of the liquid connection 700. In this way, even if ink leaks from the liquid connection 700, the ink will flow in the horizontal direction (i.e., the opening direction of the opening of the liquid connector 59a) or downward in the direction of gravity. This prevents ink from reaching the circulation pump 500, which is positioned higher in the direction of gravity. In addition, positioning the circulation pump 500 at a location separate from the liquid connection 700 also reduces the possibility of ink reaching the circulation pump 500 through the components.

[0180] 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. Therefore, the possibility of electrical malfunctions caused by ink leakage from the liquid connection portion 700 can be reduced.

[0181] Furthermore, in this embodiment, a wall portion 53b of the head housing 53 is provided. Therefore, even if ink is ejected from the opening 59b of the liquid connection portion 700, 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.

[0182] (Second Embodiment)

[0183] Next, a second embodiment of this disclosure will be described. Figure 22 This is a longitudinal sectional view of the liquid injection head in the second embodiment. In this embodiment, a second supply channel 600 is provided, through which the first pressure control chamber 122 of the first pressure regulating unit 120 in the first embodiment and the supply channel 130 are connected to each other. The second supply channel 600 is connected at one end to the upper end of the first pressure regulating chamber 122 along the direction of gravity, and at the other end to the upper end of the supply channel 130 along the direction of gravity. By providing this 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 efficiently discharged to the outside.

[0184] Specifically, the first pressure control chamber 122 of the first pressure regulating unit 120 is located on the upper side of the liquid ejector head 1 along 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 the 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. It should be noted that at the flow rate of the liquid flowing through the supply channel 130 and the second supply channel 600 during inkjet operation, the accumulated bubbles BL cannot move to the ejection module 300.

[0185] The air bubbles BL that accumulate 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 suction process that forcibly draws ink from the nozzle without performing an inkjet operation. This suction process is performed by bringing the cap member into close contact with the nozzle surface of the liquid jet head 1, and applying negative pressure to the nozzle from a negative pressure source connected to the cap member, thereby forcibly drawing ink from the nozzle. During this suction, the ink flow rate generated within the channel is higher than that generated by normal inkjet operation. Therefore, the air bubbles BL that accumulate in the upper part of the first pressure control chamber 122 and the second supply channel 600 move along with the ink through the second supply channel 600 and the supply channel 130 to the pressure chamber 12, and are then discharged from the nozzle 13 along with the ink. It should be noted that this suction process is typically performed during suction recovery processes (such as by discharging thickened ink or the like that appearing in the nozzle, pressure chamber, etc., to restore inkjet performance) and initial filling processes that fill the channels with ink.

[0186] As described above, by forming a second supply channel, air bubbles contained in the ink within the liquid jet head 1 can be collected and discharged in one go through a suction process. Therefore, the process of discharging air bubbles can be performed efficiently.

[0187] (Other embodiments)

[0188] In the above embodiments, an example has been given in which the bypass channel 160 is configured such that if the pressure generated by the circulation pump 500 exceeds a preset value, the bypass channel prevents it from affecting the injection module 300. However, if the circulation pump 500 only causes small pressure fluctuations and keeps the pressure below the preset value, the bypass channel 160 and the second pressure regulating unit 150 can be omitted.

[0189] According to this disclosure, a liquid jetting head and a liquid jetting device can be provided, which can redisperse settled components and suppress ink thickening by performing cycles within a short period of time, thereby reducing downtime.

[0190] Although the invention has been described with reference to exemplary embodiments, it should be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the appended claims should be given the broadest interpretation so as to include all such variations and equivalent structures and functions.

Claims

1. A liquid injection head, comprising: A nozzle from which liquid is ejected; The pressure chamber is connected to the injection port; A jetting element configured to jet liquid supplied to the pressure chamber from the jetting port; as well as The liquid circulates through a circulation path. The loop path includes: A supply channel through which liquid is supplied to the pressure chamber; A recovery channel for recovering liquid from the pressure chamber via the recovery channel; A circulation pump, which supplies the liquid recovered through the recovery channel to the supply channel; and A pressure regulating unit, configured to regulate the pressure of the liquid supplied to the supply channel, and The pressure P21 of the liquid in the pressure chamber set by the pressure regulating unit when the circulation pump is stopped, the pressure P22 of the liquid in the pressure chamber set by the pressure regulating unit when the circulation pump is driven, and the pressure loss ΔP from the pressure regulating unit to the pressure chamber when the circulation pump is driven have the following relationship: P22 > P21 and P22-ΔP < 0.

2. The liquid injection head according to claim 1, The pressure regulating unit includes a first pressure regulating unit connected between the supply channel and the inlet, through which liquid supplied from the liquid supply source is introduced. The first pressure regulating unit has a first liquid chamber for storing liquid supplied from the liquid supply source and the circulating pump, and a first regulating mechanism for regulating the pressure of the liquid supplied from the first liquid chamber to the supply channel.

3. The liquid injection head according to claim 2, The volume of the first liquid chamber varies depending on the amount of liquid supplied from the liquid supply source and the circulation pump. The first regulating mechanism adjusts the pressure of the liquid stored in the first liquid chamber according to the volume of the first liquid chamber.

4. The liquid injection head according to claim 2, wherein the first adjusting mechanism comprises: A first valve chamber, which is connected to a first liquid chamber via a first connecting port, and liquid supplied from the liquid supply source is supplied from the first valve chamber to the first liquid chamber via the first connecting port. A first valve switches the first communication port between an open and closed state based on the volume of the first liquid chamber.

5. The liquid injection head according to claim 4, wherein when the volume of the first liquid chamber storing the liquid is less than a predetermined volume, the first valve opens the first connection port, and when the volume of the first liquid chamber is greater than or equal to the predetermined volume, the first valve closes the first connection port.

6. The liquid injection head according to claim 4, The volume of the first liquid chamber is changed by displacement of a flexible member formed at at least a portion of the first liquid chamber. The first adjustment mechanism includes: A biasing unit configured to bias the flexible member in a direction of increasing volume of the first liquid chamber, and The first valve, which shifts according to the displacement of the flexible member, and When the flexible member is moved to a position where the volume of the first liquid chamber is less than a predetermined volume, the first valve is moved to a position where the first connection port is in an open state; and when the flexible member is moved to a position where the volume of the first liquid chamber is greater than or equal to a predetermined volume, the first valve is moved to a position where the first connection port is in a closed state.

7. The liquid injection head according to claim 2, The pressure regulating unit further includes a second pressure regulating unit, which is fluidly connected to the first liquid chamber, the recovery channel, and the circulation pump. The second pressure regulating unit has a second liquid chamber for storing liquid supplied from the first liquid chamber and the recovery channel, and a second regulating mechanism for regulating the pressure of the liquid supplied to the second liquid chamber.

8. The liquid injection head according to claim 7, The volume of the second liquid chamber varies according to the amount of liquid supplied from the liquid supply source and the circulation pump, and The second regulating mechanism adjusts the pressure of the liquid stored in the second liquid chamber according to the volume of the second liquid chamber.

9. The liquid injection head according to claim 8, wherein the second adjustment mechanism comprises: A second valve chamber, which communicates with the second liquid chamber via a second connecting port, and liquid supplied from the first liquid chamber and the recovery channel is supplied from the second valve chamber to the second liquid chamber via the second connecting port. The second valve switches the second communication port between an open and closed state based on the volume of the second liquid chamber. When the volume of the second liquid chamber storing the liquid is less than a predetermined volume, the second valve opens the second connection port; when the volume of the second liquid chamber is greater than or equal to the predetermined volume, the second valve closes the second connection port.

10. The liquid injection head according to claim 7, wherein the outlets through which the liquid stored in the first liquid chamber and the second liquid chamber are discharged are respectively provided at the lower part of the first liquid chamber and the second liquid chamber along the direction of gravity.

11. The liquid injection head according to claim 2, further comprising a second supply channel, wherein the upper part of the first liquid chamber and the supply channel are connected to each other through the second supply channel.

12. The liquid jet head of claim 1 further includes an electrical connection terminal, the electrical connection terminal being capable of applying at least a drive voltage for the circulating pump from an external power source.

13. The liquid jet head according to claim 1, wherein the circulation pump is a piezoelectric pump having a pump chamber supplied with liquid and a piezoelectric element that displaces in response to a driving voltage applied to the piezoelectric element, thereby changing the volume of the pump chamber.

14. The liquid jet head according to claim 13, wherein an AC voltage having a phase difference is applied to the piezoelectric element as a driving voltage.

15. The liquid jet head of claim 1 further includes a filter disposed between the circulation path and the liquid supply source and filtering the liquid supplied from the liquid supply source.

16. The liquid jet head of claim 15, wherein the filter is disposed along the direction of gravity.

17. A liquid injection device, comprising: Liquid injection head; A liquid supply source that supplies liquid to the liquid injection head; as well as A delivery unit configured to deliver printing media at a position opposite to the nozzle of the liquid jet head. The liquid injection head includes: A nozzle from which liquid is ejected; The pressure chamber is connected to the injection port; A jetting element configured to jet liquid supplied to the pressure chamber from the jet nozzle; and The liquid circulates through a circulation path. The loop path includes: A supply channel through which liquid is supplied to the pressure chamber; A recovery channel for recovering liquid from the pressure chamber via the recovery channel; A circulation pump, which supplies the liquid recovered through the recovery channel to the supply channel; and A pressure regulating unit, configured to regulate the pressure of the liquid supplied to the supply channel, and The pressure P21 of the liquid in the pressure chamber set by the pressure regulating unit when the circulation pump is stopped, the pressure P22 of the liquid in the pressure chamber set by the pressure regulating unit when the circulation pump is driven, and the pressure loss ΔP from the pressure regulating unit to the pressure chamber when the circulation pump is driven have the following relationship: P22 > P21 and P22-ΔP < 0.

18. The liquid jetting apparatus of claim 17, wherein the liquid jetting head is detachably attached to a carriage that moves in a main scanning direction that intersects the direction in which the transport unit transports the printing medium, and the liquid jetting head performs printing by jetting liquid from the jetting nozzle while moving together with the carriage in the main scanning direction.

19. The liquid injection device according to claim 18, The carriage has a first electrical connection portion that is electrically connected to a power source, and The liquid injection head has a second electrical connection portion, which is connected to the first electrical connection portion when the liquid injection head is attached to the carriage.

20. The liquid injection device according to claim 19, wherein electricity for generating liquid injection by the injection element and drive voltage for the circulating pump are supplied from the power source to the liquid injection head via the first electrical connection and the second electrical connection.

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