Liquid ejecting head and liquid ejecting apparatus

Abstract

The invention provides a liquid ejecting head configured to eject liquid from an ejection port, and includes: an ejection unit including a pressure chamber configured to communicate with the ejection port, a nozzle configured to communicate with the ejection port at one end, and a liquid ejecting head configured to eject liquid from the ejection port at the other end; a liquid supply apparatus includes a pressure chamber having one end open and the other end communicating with the pressure chamber, an independent supply channel configured to supply liquid to the pressure chamber, an independent collection channel configured to collect liquid from the pressure chamber, and a liquid delivery element configured to deliver liquid from the independent supply channel to the independent collection channel; and a circulation unit fluidly connected to the ejection unit and configured to circulate liquid from a common collection channel that collectively collects liquid from a plurality of the independent collection channels to a common supply channel that collectively supplies liquid to a plurality of the independent supply channels.

Description

Technical Field

[0001] This disclosure relates to a liquid jet head and a liquid jetting device equipped with the liquid jet head. Background Technology

[0002] Traditionally, one of the factors degrading image quality in liquid ejector heads is the concentration of the ink (liquid). In ejector nozzles that have not been ejected for a period of time, the ink continues to evaporate, causing it to thicken. If the ink thickens, the ejection volume and direction may change, resulting in stripes and density inconsistencies in the image, thus degrading image quality.

[0003] In the specification of U.S. Patent Application Publication No. 2020 / 0238708 (referred to as Document 1), in addition to the structure in which ink is circulated by an independent pump arranged in a pressure chamber, the following structure is disclosed: ink is circulated between the liquid jet head and the body by using a pump on the body side outside the liquid jet head.

[0004] However, in Reference 1, as the main body structure becomes larger, the flow rate of the pump on the main body side also increases accordingly, and this flow rate also affects the vicinity of the injection port, which increases the evaporation rate from the injection port. Summary of the Invention

[0005] In view of the above problems, this disclosure aims to provide a liquid jet head that can improve circulation efficiency while maintaining an appropriate flow rate near the nozzle and suppressing the evaporation rate from the nozzle.

[0006] The liquid injection head disclosed herein is a liquid injection head that ejects liquid from an injection port while moving in a predetermined direction, and is characterized by comprising: an injection unit configured to include: an injection element configured to generate energy for ejecting liquid from the injection port; a pressure chamber configured to communicate with the injection port; a nozzle configured to communicate with the injection port at one end and with the pressure chamber at the other end; an independent supply channel configured to supply liquid to the pressure chamber; an independent collection channel configured to collect liquid from the pressure chamber; and a liquid delivery element disposed between the pressure chamber and the independent supply channel and configured to deliver liquid from the independent supply channel to the independent collection channel; and a circulation unit fluidly connected to the injection unit and configured to circulate liquid from a common collection channel to a common supply channel, the common collection channel centrally collecting liquid from multiple independent collection channels, and the common supply channel centrally supplying liquid to multiple independent supply channels.

[0007] The features of this disclosure will become apparent from the following description of embodiments with reference to the accompanying drawings. The following embodiments are described by way of example. Attached Figure Description

[0008] Figure 1A and Figure 1B This is a diagram used to illustrate a liquid injection device.

[0009] Figure 2 This is an exploded perspective view of the liquid injection head.

[0010] Figure 3A and Figure 3B These are vertical cross-sectional views of the liquid injection head and enlarged cross-sectional views of the injection module.

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

[0012] Figure 5 This is a vertical cross-sectional view showing the loop path.

[0013] Figure 6 It is a schematic diagram illustrating the loop path.

[0014] Figures 7A to 7C This is a cross-sectional view showing an example of a pressure adjustment unit.

[0015] Figure 8A and Figure 8B This is a perspective view of the circulating pump.

[0016] Figure 9 It is along Figure 8A The diagram shows a cross-sectional view of the circulating pump taken by the IX-IX line.

[0017] Figures 10A to 10E This is a diagram used to illustrate the ink flow inside a liquid jet nozzle.

[0018] Figure 11A and Figure 11B This is a schematic diagram showing the circulation path in the injection unit.

[0019] Figure 12 This is a diagram showing the aperture plate 330.

[0020] Figure 13 This is a diagram showing the substrate of the jetting element.

[0021] Figures 14A to 14C This is a cross-sectional view showing the ink flow in the jetting unit.

[0022] Figure 15A and Figure 15B This is a cross-sectional view showing the area near the injection nozzle.

[0023] Figure 16A and Figure 16B This is a cross-sectional view showing a comparative example near the injection nozzle.

[0024] Figure 17 This is a diagram showing a comparative example of a jetting element substrate.

[0025] Figure 18A and Figure 18B This is a diagram showing the channel structure of a liquid injection head.

[0026] Figure 19 This diagram shows the connection between the main body of the liquid injection device and the liquid injection head.

[0027] Figure 20A and Figure 20B This is a diagram showing a portion of the injection module.

[0028] Figure 21 This is a diagram showing the jet pulse and the drive pulse of the liquid delivery element. Detailed Implementation

[0029] Hereinafter, embodiments of the invention are described with reference to the accompanying drawings; however, the invention may be practiced in any desired form, and these embodiments are not intended to limit other forms.

[0030] The following is a detailed description of preferred embodiments of the present disclosure with reference to the accompanying drawings. Note that the following embodiments are not intended to limit the scope of the present disclosure, and not all combinations of features described in these embodiments are necessary for the solutions provided by the present disclosure. Note that the same reference numerals are assigned to the same constituent elements. In the examples used to illustrate this embodiment, a thermal system that uses an electrothermal conversion element to generate bubbles to spray liquid is employed as the liquid spraying element; however, it is not limited thereto. This embodiment can also be applied to liquid spray heads using spraying systems that utilize piezoelectric elements to spray liquid or other spraying systems. Furthermore, the pumps, pressure adjustment units, etc., described below are not limited to the constructions described in the embodiments and drawings. In the following description, the basic structure of the present disclosure is described first, followed by the characteristic portions of the present disclosure.

[0031] <Liquid jetting device>

[0032] Figure 1A and Figure 1B This is a diagram illustrating a liquid injection device, and specifically an enlarged view of the liquid injection head and its surroundings. First, refer to... Figure 1A and Figure 1B The following is a description of the schematic construction of the liquid injection device 50 in this embodiment. Figure 1AThis is a perspective view schematically showing a liquid jetting device using a liquid jetting head 1. The liquid jetting device 50 of this embodiment constitutes a serial inkjet printing device that prints on a printing medium P by jetting ink as a liquid while scanning using the liquid jetting head 1.

[0033] The liquid ejector head 1 is mounted on a carriage 60. The carriage 60 reciprocates along a guide shaft 51 in the main scanning direction (X direction). Sheet-shaped printing media P is transported by transport rollers 55, 56, 57, and 58 in a secondary scanning direction (Y direction) that intersects (orthogonally in this example) the main scanning direction. Note that in the figures referred to below, the Z direction indicates the vertical direction and intersects (orthogonally in this example) the XY plane defined by the X and Y directions. The liquid ejector head 1 is configured so that it can be detached from and attached to the carriage 60 by the user.

[0034] Liquid injection head 1 is equipped with circulation unit 54 and injection unit 3, which will be described later (see Figure 2 Although the specific construction will be described later, the injection unit 3 is equipped with multiple injection ports and energy generating elements (hereinafter referred to as injection elements) that generate injection energy for ejecting liquid from each injection port.

[0035] In addition, the liquid jetting device 50 is equipped with an ink cartridge 2 (as an ink supply source) and an external pump 21, and the ink stored 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.

[0036] The liquid jetting device 50 repeatedly performs printing scans and transport operations to form a predetermined image on the printing medium P. During printing scans, the liquid jetting head 1, mounted on the carriage 60, prints by jetting ink while moving in the main scanning direction. During transport operations, the printing medium P is transported in the secondary scanning direction. Note that the liquid jetting head 1 in this embodiment can jet four types of ink: black (K), cyan (C), magenta (M), and yellow (Y), and full-color images can be printed using these inks. However, the ink that can be jetted from the liquid jetting head 1 is not limited to the four types mentioned above. This disclosure also applies to liquid jetting heads that jet other types of ink. That is, the type and quantity of ink jetted from the liquid jetting head are not limited.

[0037] Furthermore, the liquid jetting device 50 is equipped with a cap member (not shown in the figure) that covers the nozzle surface at a position separate from the transport path of the printing medium P in the X direction, forming the nozzle of the liquid jetting head. The cap member covers the nozzle surface of the liquid jetting head 1 during non-printing operations and serves to prevent the nozzle from drying out, protect the nozzle, and facilitate ink intake operations.

[0038] Note, regarding Figure 1A The liquid ejector head 1 shown, although illustratively including four circulation units 54 corresponding to four types of ink, is sufficient to include circulation units 54 corresponding to the type of liquid to be ejected. Furthermore, multiple circulation units 54 may be included for the same type of liquid. That is, the liquid ejector head 1 may be configured with one or more circulation units. It is also possible to circulate only at least one type of ink instead of all four types.

[0039] Figure 1B This is a block diagram showing the control system of the liquid jetting device 50. The CPU 103 functions as a control unit that controls the operation of various parts of the liquid jetting device 50 based on programs such as processing procedures stored in the ROM 101. The RAM 102 serves as a working area for the CPU 103 to perform processing, etc. The CPU 103 receives image data from the host device 400 outside the liquid jetting device 50 to control the head driver 1A and to control the driving of the jetting element 15 and the liquid delivery element 1001 installed in the jetting unit 3. Furthermore, the CPU 103 controls various drivers installed in the liquid jetting device. For example, the CPU 103 controls the motor driver 105A for the carriage motor 105 that moves the carriage 60, the motor driver 104A for the transport motor 104 that transports the printing media P, etc. Additionally, the CPU 103 controls the pump driver 500A that drives the circulation pump 500 (described later) and the pump driver 21A of the external pump 21. Note that although... Figure 1B The illustration shows a form of processing involving receiving image data from the host device 400, but the processing can also be performed in the liquid jetting device 50 without relying on data from the host device 400.

[0040] <Basic Structure of Liquid Jet Heads>

[0041] Figure 2 This is an exploded perspective view of the liquid injection head 1 in this embodiment. Figure 3A and Figure 3B yes Figure 2 The cross-sectional view of the liquid injection head 1 taken along line IIIa-IIIa is shown. Figure 3A This is a cross-sectional view of the liquid injection head 1 from the vertical direction. Figure 3B yes Figure 3A The image shown is an enlarged view of the injection module. The following text will primarily refer to... Figure 2 , Figure 3A and Figure 3B The basic structure of the liquid injection head 1 in this embodiment will be described, and references will also be made as appropriate. Figure 1A and Figure 1B.

[0042] like Figure 2 As shown, the liquid ejector head 1 is equipped with a circulation unit 54 and an ejection unit 3, which ejects ink supplied from the circulation unit 54 onto the printing medium P. In this embodiment, the liquid ejector head 1 is fixedly supported on the carriage 60 by a positioning unit and electrical contacts (not shown) mounted on the carriage 60 of the liquid ejection device 50. The liquid ejector head 1 moves along the carriage 60 together with the carriage. Figure 1A Ink is ejected while the main scanning direction (X direction) is moved as shown, and printing is performed on the printing medium P.

[0043] The external pump 21 connected to the ink cartridge 2, which serves as the ink supply source, is equipped with an ink supply tube 59 (see...). Figure 1A A liquid connector (not shown) is installed at the front end of the ink supply tube 59. When the liquid ejector head 1 is installed on the liquid ejection device 50, the liquid connector installed at the front end of the ink supply tube 59 is airtightly connected to the liquid connector inlet 53a, which serves as the liquid inlet and is installed in the head shell 53 of the liquid ejector head 1. Thus, an ink supply path is formed from the ink cartridge 2 to the liquid ejector head 1 via the external pump 21. Since four types of ink are used in this embodiment, four sets of ink cartridges 2, external pumps 21, ink supply tubes 59, and circulation units 54 corresponding to each ink are installed, thereby independently forming four ink supply paths corresponding to each ink. In this way, the liquid ejection device 50 of this embodiment includes an ink supply system that supplies ink from the ink cartridge 2 installed outside the liquid ejector head 1. Note that the liquid ejection device 50 of this embodiment does not include an ink collection system for collecting ink inside the liquid ejector head 1 into the ink cartridge 2. Therefore, although the liquid ejector head 1 is equipped with a liquid connector inlet 53a that connects to the ink supply tube 59 of the ink cartridge 2, it is not equipped with a connector inlet that connects to the tube used to collect ink from the liquid ejector head 1 into the ink cartridge 2. Note that the liquid connector inlet 53a is installed for each ink cartridge.

[0044] exist Figure 3A In the diagram, 54B indicates a circulation unit for black ink, 54C indicates a circulation unit for cyan ink, 54M indicates a circulation unit for magenta ink, and 54Y indicates a circulation unit for yellow ink. Each circulation unit has a substantially identical structure, and in this embodiment, unless otherwise specified, each circulation unit is referred to as circulation unit 54.

[0045] exist Figure 2 and Figure 3A In the process, the spraying unit 3 includes two spraying modules 300, a first support member 4, a second support member 7, an electrical wiring member (electrical wiring tape) 5, and an electrical contact substrate 6. For example... Figure 3BAs shown, the 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 mounted on one side of the silicon substrate 310. Although Figure 3A and Figure 3B Not shown in the figure, but the silicon substrate 310 is also equipped with a plurality of liquid delivery elements 1001, which will be described later (see Figure 1). Figure 20A and Figure 20B In this embodiment, the spraying element 15 is composed of an electrothermal conversion element (heater), which generates thermal energy as the spraying energy for spraying liquid. Power is supplied to each spraying element 15 via electrical wiring formed on the silicon substrate 310 using film formation technology.

[0046] Furthermore, the nozzle 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 jetting nozzle 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 collection channel 19 are formed in the silicon substrate 310. Additionally, in the silicon substrate 310, a supply connection channel 323 connecting the common supply channel 18 to each pressure chamber 12 and a collection connection channel 324 connecting the common collection channel 19 to each pressure chamber 12 are formed. In this embodiment, one jetting module 300 is configured to jet two types of ink. That is, in... Figure 3A In the two jetting modules shown, the jetting module 300 on the left jettisons black and cyan ink, while the jetting module 300 on the right jettisons magenta and yellow ink. Note that this combination is an example, and any combination of inks can be used. A configuration can exist where one jetting module jettisons one type of ink, or where one jetting module jettisons three or more types of ink. The two jetting modules 300 do not need to jet the same amount of ink of the same type. A configuration can exist equipped with one jetting module 300, or equipped with three or more jetting modules 300. Furthermore, in Figure 3A In the example shown, two nozzle arrays extending along the Y direction are formed for ink of one color. For each of the plurality of nozzles 13 constituting the respective nozzle array, a pressure chamber 12, a common supply channel 18, and a common collection channel 19 are formed.

[0047] The ink supply port and ink collection port, described later, are formed on the back side of the silicon substrate 310. Figure 3B On the upper surface of the middle. The ink supply port supplies ink from the ink supply channel 48 to multiple common supply channels 18, and the ink collection port collects ink from multiple common collection channels 19 to the ink collection channel 49.

[0048] Note that the ink supply port and ink collection port referred to here are openings used for supplying and collecting ink during the forward ink circulation described later. That is, during the forward ink circulation, ink is supplied from the ink supply port to the respective common supply channels 18, and ink is collected from the respective common collection channels 19 to the ink collection port. However, there are cases where ink circulation occurs in reverse. In this case, ink is supplied from the aforementioned ink collection port to the common collection channel 19, and ink is collected from the common supply channel 18 to the ink supply port.

[0049] like Figure 3A As shown, the back of the injection module 300 ( Figure 3A The upper surface of the middle part is adhered and fixed to one surface of the first support member 4. Figure 3A (The lower surface of the first support member 4). The ink supply channel 48 and the ink collection channel 49 are formed to extend from one surface of the first support member 4 to the other surface of the first support member 4. One opening of the ink supply channel 48 communicates with the aforementioned ink supply port of the silicon substrate 310, and one opening of the ink collection channel 49 communicates with the aforementioned ink collection port of the silicon substrate 310. Note that the ink supply channel 48 and the ink collection channel 49 are installed independently for each type of ink.

[0050] In addition, it has an opening 7a for inserting the injection module 300 (see Figure 2 The second support member 7 is adhered and fixed to one surface of the first support member 4. Figure 3A (The upper surface of the middle). The second support member 7 holds the electrical wiring member 5, which is electrically connected to the jetting module 300. The electrical wiring member 5 is a member for applying electrical signals for ink jetting to the jetting module 300. The electrical connection between the jetting module 300 and the electrical wiring member 5 is sealed with a sealing material (not shown in the figure) to prevent ink corrosion and external impact.

[0051] Furthermore, the electrical contact substrate 6 is thermo-pressed together with the end 5a of the electrical wiring component 5 (see figure) using an anisotropic conductive film (not shown). Figure 2 The electrical wiring component 5 is joined together to electrically connect it to the electrical contact substrate 6. The electrical contact substrate 6 has an external signal input terminal (not shown) for receiving electrical signals from the liquid injection device 50.

[0052] In addition, connecting component 8 (see Figure 3A It is installed between the first support member 4 and the circulation unit 54. For each type of ink, a supply port 88 and a collection port 89 are formed in the connecting member 8. The supply port 88 and the collection port 89 allow the ink supply channel 48 and the ink collection channel 49 of the first support member 4 to communicate with the channels formed in the circulation unit 54. Note that in Figure 3AIn this configuration, supply port 88B and collection port 89B correspond to black ink, while supply port 88C and collection port 89C correspond to cyan ink. Furthermore, supply port 88M and collection port 89M correspond to magenta ink, while supply port 88Y and collection port 89Y correspond to yellow ink.

[0053] Note that the openings at one end of the ink supply channel 48 and the ink collection channel 49 in the first support member 4 each have a small opening area corresponding to the ink supply port and ink collection port of the silicon substrate 310, respectively. On the other hand, the openings at the other end of the ink supply channel 48 and the ink collection channel 49 in the first support member 4 each have a shape enlarged to the same width as the large opening area formed by the channel of the connecting member 8 according to the circulation unit 54. By adopting such a configuration, the increase in channel resistance of the ink collected from each collection channel can be suppressed. However, the shapes of the openings at one end and the other end of the ink supply channel 48 and the ink collection channel 49 are not limited to the examples described above.

[0054] In the liquid jet head 1 with the above-described structure, ink supplied to the circulation unit 54 passes through the supply port 88 of the connecting member 8 and the ink supply channel 48 of the first support member 4, and flows from the ink supply port of the jet module 300 into the common supply channel 18. Subsequently, ink flows from the common supply channel 18 into the pressure chamber 12 via the supply connection channel 323, and a portion of the ink that has flowed into the pressure chamber is ejected from the jet port 13 by the drive of the jet element 15. The remaining ink that has not yet been ejected flows from the pressure chamber 12 through the collection connection channel 324 and the common collection channel 19, and from the ink collection port into the ink collection channel 49 of the first support member 4. Furthermore, the ink that has flowed into the ink collection channel 49 flows into the circulation unit 54 through the collection port 89 of the connecting member 8 to be collected.

[0055] <Components of a Loop Unit>

[0056] Figure 4 This is a schematic view of a circulation unit 54 corresponding to a type of ink used in the printing apparatus of this embodiment. A filter 110, a first pressure adjustment unit 120, a second pressure adjustment unit 150, and a circulation pump 500 are arranged 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 and collecting ink from the injection module 300 in the liquid injection head 1.

[0057] <Circulation path in a liquid jet head>

[0058] Figure 5 This is a schematic vertical cross-sectional view illustrating the circulation path of a type of ink (one ink color) constructed in a liquid injection head 1. To illustrate the circulation path more clearly, Figure 5 The relative positions of the various components (first pressure adjustment unit 120, second pressure adjustment unit 150, circulating pump 500, etc.) are simplified. Therefore, the relative positions of the components are the same as those described later. Figure 19 The relative positions of the structures within them differ. Furthermore, Figure 6 It is shown schematically. Figure 5 The diagram shows a loop path. Figure 5 and Figure 6 As shown, the first pressure adjustment unit 120 includes a first valve chamber 121 and a first pressure control chamber 122. The second pressure adjustment unit 150 includes a second valve chamber 151 and a second pressure control chamber 152. The first pressure adjustment unit 120 is configured to have a control pressure that is relatively higher than the control pressure of the second pressure adjustment unit 150. In this embodiment, by using these two pressure adjustment units 120 and 150, circulation within a constant pressure range is achieved in the circulation path. Furthermore, this configuration allows ink to flow through the pressure chamber 12 (jet element 15) at a flow rate corresponding to the pressure difference between the first pressure adjustment unit 120 and the second pressure adjustment unit 150. Referring below... Figure 5 and Figure 6 The circulation path in the liquid jet head 1 and the ink flow within that path are described. Note that the arrows in the accompanying figures indicate the direction of the ink flow.

[0059] First, the connection status of each component in the liquid injection head 1 is described.

[0060] The ink cartridge 2 (see) is installed outside the liquid ejector head 1. Figure 6 The ink contained in the liquid jet head 1 is sent to the external pump 21 via the ink supply pipe 59 (see ink supply pipe 59). Figure 1A The filter 110 is connected to the circulation unit 54. The filter 110 is installed 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 via... Figure 5 The valve 190A shown has a connection port 191A that is open and closed, which is connected to the first pressure control chamber 122.

[0061] 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 circulating pump 500. The supply channel 130 is connected to the common supply channel 18 via the ink supply port installed in the injection module 300. Furthermore, the bypass channel 160 is connected to the second valve chamber 151 installed in the second pressure adjustment unit 150. The second valve chamber 151 is connected via… Figure 5 The valve 190B shown has a connection port 191B that connects to the second pressure control chamber 152 when it is open and closed. Note that in Figure 5 and Figure 6 In the example shown, one end of the bypass channel 160 is connected to the first pressure control chamber 122 of the first pressure adjustment unit 120, while the other end of the bypass channel 160 is connected to the second valve chamber 151 of the second pressure adjustment unit 150. However, it is also possible that one end of the bypass channel 160 is connected to the supply channel 130, while the other end of the bypass channel 160 is connected to the second valve chamber 151.

[0062] The second pressure control chamber 152 is connected to the collection channel 140. The collection channel 140 is connected to the common collection channel 19 via the ink collection port installed in the jet module 300. Furthermore, the second pressure control chamber 152 is connected to the circulation pump 500 via the pump inlet channel 170. Note that in Figure 5 In the middle, 170a indicates the inlet of pump inlet channel 170.

[0063] Next, the ink flow in the liquid jet head 1 with the above-described structure will be described. For example... Figure 6 As shown, the ink contained in the ink cartridge 2 is pressurized by an external pump 21 installed in the liquid jet device 50, thereby becoming a positive pressure ink flow, which is then supplied to the circulation unit 54 of the liquid jet head 1.

[0064] Ink supplied to circulation unit 54 passes through filter 110, removing impurities such as dust and air bubbles, and then flows into first valve chamber 121 installed in first pressure adjustment unit 120. Although the ink pressure decreases due to pressure loss as it passes through filter 110, the ink pressure is positive during this stage. Subsequently, if valve 190A is open, the ink flowing into first valve chamber 121 flows into first pressure control chamber 122 through connection port 191A. The ink flowing into first pressure control chamber 122 switches from positive pressure to negative pressure due to pressure loss as it passes through connection port 191A.

[0065] Next, the ink flow in the circulation path will be described. The circulation pump 500 operates to deliver ink drawn from the pump inlet channel 170 located upstream to the pump outlet channel 180 downstream. Thus, driven by the pump, ink supplied to the first pressure control chamber 122 flows into the supply channel 130 and the bypass channel 160 together with ink delivered from the pump outlet channel 180. Note that, as described in detail later, in this embodiment, a piezoelectric diaphragm pump, whose drive source is a piezoelectric element attached to a diaphragm, is used as the circulation pump capable of conveying liquid. The piezoelectric diaphragm pump is a pump that changes the internal volume of the pump chamber by inputting a drive voltage to the piezoelectric element, causing two check valves to move alternately due to pressure fluctuations, thereby conveying liquid.

[0066] Ink that has flowed into supply channel 130 flows from the ink supply port of the ejection module 300 to the pressure chamber 12 via the common supply channel 18, and a portion of the ink is ejected from the ejection port 13 by the drive (heating) of the ejection element 15. Furthermore, the remaining ink not used for ejection flows out of the pressure chamber 12, through the common collection channel 19, and then into the collection channel 140 connected to the ejection module 300. The ink that has flowed into the collection channel 140 flows into the second pressure control chamber 152 of the second pressure adjustment unit 150.

[0067] On the other hand, ink that has flowed from the first pressure control chamber 122 into the bypass channel 160 flows into the second valve chamber 151, and then into the second pressure control chamber 152 through the connecting port 191B. The ink flowing into the second pressure control chamber 152 through the bypass channel 160 and the ink collected from the collection channel 140 are drawn into the circulation pump 500 through the pump inlet channel 170 under the drive of the circulation pump 500. The ink drawn into the circulation pump 500 is then sent to the pump outlet channel 180 and flows back into the first pressure control chamber 122. Subsequently, ink flowing from the first pressure control chamber 122 into the second pressure control chamber 152 via the supply channel 130 through the injection module 300, and ink flowing into the second pressure control chamber 152 via the bypass channel 160, flows into the circulation pump 500. The ink is then sent from the circulation pump 500 to the first pressure control chamber 122. In this way, the ink circulates in the circulation path.

[0068] As described above, in this embodiment, the circulation pump 500 circulates the liquid along the circulation path formed in the liquid jet head 1. Therefore, the thickening of the ink in the jet module 300 and the deposition of ink sediment components (i.e., coloring materials) can be suppressed, and the flowability of the ink in the jet module 300 and the jetting characteristics of the jet nozzle can be maintained in a good state.

[0069] Furthermore, since the circulation path in this embodiment is constructed within the liquid ejector head 1, the length of the circulation path can be significantly shortened compared to the case where the ink circulates between the ink cartridge 2, which is mounted outside the liquid ejector head, and the liquid ejector head 1. Therefore, a small circulation pump can be used to circulate the ink.

[0070] Furthermore, this configuration allows for the installation of only a channel for supplying ink, serving as the connection between the liquid ejector head 1 and the ink cartridge 2. In other words, a channel for collecting ink from the liquid ejector head 1 to the ink cartridge 2 is not required. Therefore, the connection between the ink cartridge 2 and the liquid ejector head 1 only requires a tube for supplying ink, and not a tube for collecting ink. Thus, the internal structure of the liquid ejector device 50 can be simplified by utilizing a reduced number of tubes, thereby enabling miniaturization of the entire device. Furthermore, the reduced number of tubes reduces ink pressure fluctuations caused by tube vibration associated with the main scan of the liquid ejector head 1. Moreover, tube vibration during the main scan of the liquid ejector head 1 is considered a drive load on the carriage motor that drives the carriage 60. Therefore, the reduced number of tubes lowers the drive load on the carriage motor, simplifying the main scan mechanism, including the carriage motor, etc. Furthermore, since ink collection from the liquid ejector head to the ink cartridge is not required, the external pump 21 can also be miniaturized. In this way, according to this embodiment, miniaturization and cost reduction of the liquid ejector device 50 can be achieved.

[0071] <Pressure Adjustment Unit>

[0072] Figures 7A to 7C This is a diagram showing an example of a pressure regulating unit. (Refer to...) Figures 7A to 7C This section describes in detail the structure and function of the pressure adjustment units (first pressure adjustment unit 120 and second pressure adjustment unit 150) built into the liquid injection head 1 described above. Note that the first pressure adjustment unit 120 and the second pressure adjustment unit 150 have substantially the same structure. Therefore, the following description uses the first pressure adjustment unit 120 as an example, while the second pressure adjustment unit 150 will only be described using... Figures 7A to 7C The symbols corresponding to the components of the first pressure adjustment unit are marked together. In the case of the second pressure adjustment unit 150, the first valve chamber 121 and the first pressure control chamber 122 described below will be understood as the second valve chamber 151 and the second pressure control chamber 152.

[0073] The first pressure adjustment unit 120 includes 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 mounted in the cylindrical housing 125. However, the first valve chamber 121 communicates with the first pressure control chamber 122 via a communication port 191 formed in the partition 123. The first valve chamber 121 is equipped with a valve 190 that switches the communication between the first valve chamber 121 and the first pressure control chamber 122 at the communication port 191. The valve 190 is held in a position facing the communication port 191 by a valve spring 200 and has a configuration that allows it to come into close contact with the partition 123 by the biasing force of the valve spring 200. When the valve 190 is in close contact with the partition 123, the flow of ink at the communication port 191 is blocked. Note that, to increase the airtightness with the partition 123, the contact portion between the valve 190 and the partition 123 is preferably formed of an elastic member. Furthermore, the valve shaft 190a, inserted into the communication port 191, is mounted protrudingly in the center of the valve 190. By pressing the valve shaft 190a against the biasing force of the valve spring 200, the valve 190 separates from the partition 123, thereby allowing ink to flow through the communication port 191. Hereinafter, the state in which the valve 190 blocks the flow of ink at the communication port 191 is referred to as the "closed state," while the state in which the valve 190 allows the flow of ink at the communication port 191 is referred to as the "open state."

[0074] The opening of the cylindrical housing 125 is closed by the flexible member 230 and the pressure plate 210. The first pressure control chamber 122 is formed by the flexible member 230, the pressure plate 210, the peripheral wall of the housing 125, and the partition 123. The pressure plate 210 is configured to shift according to the displacement of the flexible member 230. Although the materials of the pressure plate 210 and the flexible member 230 are not particularly limited, for example, the pressure plate 210 can be made of a resin-molded component, and the flexible member 230 can be made of a resin film. In this case, the pressure plate 210 can be fixed to the flexible member 230 by thermal welding.

[0075] A pressure adjusting spring 220 (biasing member) is installed between the pressure plate 210 and the partition plate 123. Due to the biasing force of the pressure adjusting spring 220, such as Figure 7AAs shown, the pressure plate 210 and flexible member 230 are biased in the direction of increasing the internal volume of the first pressure control chamber 122. Furthermore, if the pressure in the first pressure control chamber 122 decreases, the pressure plate 210 and flexible member 230 overcome the pressure of the pressure adjusting spring 220 and shift in the direction of decreasing the internal volume of the first pressure control chamber 122. Moreover, if the internal volume of the first pressure control chamber 122 decreases to a certain amount, the pressure plate 210 abuts against the valve shaft 190a of the valve 190. Thereafter, if the internal volume of the first pressure control chamber 122 decreases further, the valve 190 and valve shaft 190a move together against the biasing force of the valve spring 200 to separate from the partition 123. Therefore, the communication port 191 changes to the open state. Figure 7B (State).

[0076] In this embodiment, the connection in the circulation path is configured such that when the connection port 191 is in the open state, the pressure in the first valve chamber 121 is higher than the pressure in the first pressure control chamber 122. Therefore, if the connection port 191 is in the open state, ink flows from the first valve chamber 121 into the first pressure control chamber 122. Due to this ink inflow, the flexible member 230 and the pressure plate 210 are displaced in a direction that increases the 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 is brought into close contact with the partition 123 due to the biasing force of the valve spring 200, causing the connection port 191 to be in the closed state. Figure 7C (State).

[0077] In this manner, in the first pressure adjustment unit 120 according to this embodiment, if the pressure inside the first pressure control chamber 122 decreases to a certain pressure or lower (e.g., if the negative pressure increases), ink flows out from the first valve chamber 121 via the connection port 191. Therefore, this configuration prevents the pressure in the first pressure control chamber 122 from decreasing further. Thus, the first pressure control chamber 122 is controlled to maintain the pressure within a certain range.

[0078] Next, the pressure in the first pressure control chamber 122 will be described in detail.

[0079] The following description is based on the assumption that, as described above, the flexible member 230 and the pressure plate 210 are displaced according to the pressure of the first pressure control chamber 122, causing the pressure plate 210 to abut against the valve shaft 190a, thereby turning the communication port 191 into the open state. Figure 7B (State of the pressure plate 210). Here, the relationship between the forces acting on the pressure plate 210 is represented by the following formula 1.

[0080] P2×S2+F2+(P1-P2)×S1+F1=0...Formula 1

[0081] Furthermore, Formula 1 regarding the rearrangement of P2 is as follows.

[0082] P2=-(F1+F2+P1×S1) / (S2-S1)...Formula 2

[0083] P1: Pressure (gauge pressure) in the first valve chamber 121

[0084] P2: Pressure (gauge pressure) in the first pressure control chamber 122

[0085] F1: The elastic force of valve spring 200

[0086] F2: The elasticity of the pressure adjusting spring 220

[0087] S1: Pressure-bearing area of ​​valve 190

[0088] S2: The pressure area of ​​pressure plate 210

[0089] Note that for the spring force F1 of valve spring 200 and the spring force F2 of pressure adjusting spring 220, it is assumed that the direction of pushing valve 190 and pressure plate 210 is positive. Figures 7A to 7C (to the left in the middle). In addition, regarding the pressure P1 in the first valve chamber 121 and the pressure P2 in the first pressure control chamber 122, P1 is configured to satisfy the relationship P1≥P2.

[0090] 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. Once the connection port 191 is switched to the open state, due to the structure with the relationship P1≥P2, ink flows from the first valve chamber 121 to the first pressure control chamber 122. As a result, the pressure P2 in the first pressure control chamber 122 no longer decreases, and P2 is maintained at a pressure within a certain range.

[0091] On the other hand, such as Figure 7C As shown in Equation 3, when the pressure plate 210 changes to a state where it does not abut against the valve shaft 190a, thereby turning the communication port 191 into a closed state, the relationship between the forces acting on the pressure plate 210 is as shown in Equation 3.

[0092] P3×S3+F3=0...Formula 3

[0093] Note that Formula 3 regarding the rearrangement of P3 is as follows.

[0094] P3=-F3 / S3...Formula 4

[0095] F3: The elastic force of the pressure adjusting spring 220 when the pressure plate 210 and the valve shaft 190a are not in contact with each other.

[0096] P3: Pressure (gauge pressure) in the first pressure control chamber 122 when the pressure plate 210 and valve shaft 190a are not in contact with each other.

[0097] S3: The pressure-bearing area of ​​the pressure plate 210 when the pressure plate 210 and the valve 190 are not in contact with each other.

[0098] Note that in Figure 7C The diagram shows the following state: the pressure plate 210 and the flexible member 230 are displaced to their maximum displacement limit in the rightward direction. 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 displacement of the pressure plate 210 and the flexible member 230. Figure 7C The state changes depending on the shift amount during the period. Specifically, if it is related to... Figure 7C Compared to the previous version, the pressure plate 210 and the flexible component 230 are... Figures 7A to 7C Moving the pressure plate 210 to the left reduces its pressure-bearing area S3 and increases the spring force F3 of the pressure adjusting spring 220. As a result, according to Formula 4, the pressure P3 in the first pressure control chamber 122 decreases. Therefore, according to Formulas 2 and 4, when moving from the center to the left... Figure 7B state towards Figure 7C During the state transition, the pressure in the first pressure control chamber 122 gradually increases (that is, the negative pressure weakens and moves closer to the positive pressure side). In other words, the pressure plate 210 and the flexible member 230 gradually shift to the right from the open state of the communication port 191, and the pressure in the first pressure control chamber gradually increases, while the internal volume of the first pressure control chamber 122 eventually reaches its displacement limit. That is, the negative pressure weakens.

[0099] <Circulation Pump>

[0100] Next, refer to Figure 8A , Figure 8B and Figure 9 The structure and function of the circulating pump 500 built into the liquid injection head 1 described above are described in detail.

[0101] Figure 8A and Figure 8B This is an external perspective view of the Circulation Pump 500. Figure 8A This is a perspective view showing the front of the circulating pump 500, while Figure 8BThis is a perspective view showing the rear of the circulation pump 500. The circulation pump 500 has a housing 505 and a cover 507 fixed to the housing 505. The housing 505 has a body 505a and a channel connecting member 505b adhered to the outer surface of the body 505a. The body 505a and the channel connecting member 505b are each provided with a pair of interconnecting through holes installed in two different locations. The pair of through holes installed in one location forms a pump supply hole 501, while the pair of through holes installed in 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, while 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) Figure 9 And it is discharged from the pump discharge port 502.

[0102] Figure 9 It is along Figure 8A The diagram shows a cross-sectional view of the circulating pump 500 taken along line IX-IX. A diaphragm 506 is joined to the inner surface of the pump housing 505, thereby forming a pump chamber 503 between the diaphragm 506 and a groove 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 installed in the middle portion of the pump supply port 501, and a check valve 504b is installed in the middle portion of the pump discharge port 502. Specifically, the check valve 504a is arranged such that a portion of it can move to the left in the space 512a formed in the middle portion of the pump supply port 501, as shown in the figure. Similarly, the check valve 504b is arranged such that a portion of it can move to the right in the space 512b formed in the middle portion of the pump discharge port 502, as shown in the figure.

[0103] If the internal volume of pump chamber 503 increases due to the displacement of diaphragm 506, causing pressure reduction in pump chamber 503, then check valve 504a separates from the opening of pump supply port 501 inside space 512a (i.e., moves to the left in the figure). Because check valve 504a separates from the opening of pump supply port 501 inside space 512a, pump supply port 501 becomes open, allowing ink flow. Furthermore, if the internal volume of pump chamber 503 decreases due to the displacement of diaphragm 506, causing pressure increase in pump chamber 503, then check valve 504a comes into close contact with the wall surrounding the opening of pump supply port 501. As a result, pump supply port 501 becomes closed, blocking ink flow.

[0104] On the other hand, if the pump chamber 503 is depressurized, the check valve 504b comes into close contact with the wall surrounding the opening of the pump housing 505 and changes to a closed state, blocking the ink flow at the pump discharge port 502. Furthermore, if the pump chamber 503 is pressurized, the check valve 504b separates from the opening of the pump housing 505 and moves toward space 512b (i.e., to the right in the figure), thereby allowing the ink flow at the pump discharge port 502.

[0105] Note that each of the check valves 504a and 504b may be made of any material capable of deforming according to the pressure inside the pump chamber 503, for example, it may be formed of an elastic member (such as EPDM or an elastomer), or a membrane or sheet made of polypropylene, etc. However, it is not limited to this.

[0106] As described above, the pump chamber 503 is formed by joining the pump housing 505 with the diaphragm 506. Therefore, the pressure in the pump chamber 503 changes as the diaphragm 506 deforms. For example, if the diaphragm 506 shifts towards the pump housing 505 (shifting to the right in the figure) and the internal volume of the pump chamber 503 decreases, the pressure inside the pump chamber 503 increases. Consequently, the check valve 504b, arranged to face the pump discharge port 502, opens, allowing ink to be discharged from the pump chamber 503. At this time, the check valve 504a, arranged to face the pump supply port 501, is in close contact with the wall surrounding the pump supply port 501, thus preventing ink from flowing back from the pump chamber 503 to the pump supply port 501.

[0107] Conversely, when the diaphragm 506 shifts in the direction that expands the pump chamber 503, the pressure in the pump chamber 503 decreases. Therefore, the check valve 504a, arranged to face the pump supply port 501, opens, allowing ink to be supplied to the pump chamber 503. At this time, the check valve 504b, arranged in the pump discharge port 502, comes into close contact with the wall surrounding the opening formed in the pump housing 505, thereby blocking the opening. Therefore, backflow of ink from the pump discharge port 502 into the pump chamber 503 is prevented.

[0108] In this way, ink is drawn in and discharged from the circulating pump 500 by the deformation of the diaphragm 506, which changes the pressure inside the pump chamber 503. If air bubbles enter the pump chamber 503, even if the diaphragm 506 shifts, the expansion and contraction of the bubbles will reduce the pressure change inside the pump chamber 503, thus reducing the liquid delivery rate. Therefore, the pump chamber 503 is arranged parallel to gravity, so that air bubbles entering the pump chamber 503 can be easily collected at the top of the pump chamber 503, and the pump discharge port 502 is arranged above the center of the pump chamber 503. Therefore, the performance of discharging air bubbles from inside the pump can be improved, thus stabilizing the flow rate.

[0109] <Ink Stream in a Liquid Jet Head>

[0110] Figures 10A to 10E This is a diagram illustrating the ink flow inside a liquid ejector head. (See reference...) Figures 10A to 10E Describes the ink circulation inside the liquid ejector head 1. To illustrate the ink circulation path more clearly, a simplified diagram is provided. Figures 10A to 10E The relative positions of the various components (first pressure adjustment unit 120, second pressure adjustment unit 150, circulating pump 500, etc.) are described below. Therefore, the relative positions of the components are consistent with those described later. Figure 19 The relative positions of the structures in the text are different. Figure 10A This diagram schematically illustrates the ink flow during a printing operation where ink is ejected from nozzle 13. Note that the arrows in the diagram indicate the ink flow. In this embodiment, both the external pump 21 and the circulation pump 500 are started for the printing operation. Note that the external pump 21 and the circulation pump 500 can be driven independently of the printing operation. Furthermore, the external pump 21 and the circulation pump 500 can be driven independently of each other.

[0111] During the printing operation, the circulation pump 500 is in the ON state (driven state), so the ink flowing from the first pressure control chamber 122 flows into the supply channel 130 and the bypass channel 160. The ink flowing into the supply channel 130 passes through the jetting module 300 and then flows into the collection channel 140 so that it can be subsequently supplied to the second pressure control chamber 152.

[0112] 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. Here, based on the relationship in Formula 2 above, the control pressure caused by the first valve chamber 121 is set higher than the control pressure of the first pressure control chamber 122. Therefore, the ink inside the first pressure control chamber 122 is supplied back to the injection module 300 via the supply channel 130 without flowing into the first valve chamber 121. The ink flowing into the injection module 300 passes through the collection channel 140, the second pressure control chamber 152, the pump inlet channel 170, the circulation pump 500, and the pump outlet channel 180, and then flows back into the first pressure control chamber 122. Ink circulation within the liquid injection head 1 is performed as described above.

[0113] In the aforementioned ink circulation, the circulation volume (flow rate) of ink in the ejection module 300 is determined by the pressure difference between the control pressure of the first pressure control chamber 122 and the control pressure of the second pressure control chamber 152. Furthermore, this pressure difference is set to achieve a circulation volume that can suppress ink thickening near the ejection nozzle in the ejection module 300. Additionally, the amount of ink consumed during printing is supplied from the ink cartridge 2 via the filter 110 and the first valve chamber 121 to the first pressure control chamber 122. The mechanism for supplying the consumed ink is described in detail. Because the amount of ink in the circulation path decreases, the pressure in the first pressure control chamber decreases, resulting in a reduction in the amount of ink in the first pressure control chamber 122. As the amount of ink in the first pressure control chamber 122 decreases, the internal volume of the first pressure control chamber 122 decreases. Due to the reduction in the internal volume of the first pressure control chamber 122, the connection port 191A becomes open, and ink is supplied from the first valve chamber 121 to the first pressure control chamber 122. The supplied ink experiences pressure loss as it passes through the connection port 191A from the first valve chamber 121 and flows into the first pressure control chamber 122, thus switching the ink from a positive pressure state to a negative pressure state. Then, as ink flows from the first valve chamber 121 into the first pressure control chamber 122 and the pressure in the first pressure control chamber increases, the internal volume of the first pressure control chamber increases, thereby causing the connection port 191A to close. In this way, as ink is consumed, the connection port 191A alternates between an open and closed state. Furthermore, when ink is not consumed, the connection port 191A remains in the closed state.

[0114] Figure 10B The illustration schematically shows the ink flow immediately following the termination of the printing operation and the switching of the circulation pump 500 to the OFF state (stopped state). At the point when the printing operation terminates and the circulation pump 500 is turned off, the pressure in the first pressure control chamber 122 and the pressure in the second pressure control chamber 152 are both the pressures controlled during the printing operation. Therefore, ink movement occurs 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, such as... Figure 10B As shown. Specifically, an ink flow continuously occurs from the first pressure control chamber 122 to the jet module 300 via the supply channel 130, and then to the second pressure control chamber 152 via the collection channel 140. In addition, an ink flow continuously occurs from the first pressure control chamber 122 to the second pressure control chamber 152 via the bypass channel 160 and the second valve chamber 151.

[0115] The amount of ink that moves from the first pressure control chamber 122 to the second pressure control chamber 152 via these ink flows is supplied from the ink cartridge 2 through the filter 110 and the first valve chamber 121 to the first pressure control chamber 122. Therefore, the internal contents of the first pressure control chamber 122 remain constant. Based on the relationship in Formula 2 above, if the internal contents of the first pressure control chamber 122 are constant, the spring force F1 of the valve spring 200, the spring force F2 of the pressure adjusting spring 220, 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 is determined based on the change in the pressure (gauge pressure) P1 in the first valve chamber 121. Therefore, if the pressure P1 in the first valve chamber 121 does not change, the pressure P2 in the first pressure control chamber 122 remains the same as the pressure controlled during the printing operation.

[0116] On the other hand, the pressure in the second pressure control chamber 152 changes over time according to the changes in the internal contents caused by the ink flowing from the first pressure control chamber 122. Specifically, as Figure 10C As shown, the pressure in the second pressure control chamber 152 is determined according to Formula 2 from... Figure 10B The state changes until the connection port 191 turns to the closed state, then the second valve chamber 151 and the second pressure control chamber 152 turn to the non-connected state. Afterwards, the pressure plate 210 and valve shaft 190a enter a non-abutment state, and the connection port 191 turns to the closed state. Furthermore, as... Figure 10D As shown, ink flows from collection channel 140 into the second pressure control chamber 152. This ink inflow causes displacement of the pressure plate 210 and flexible member 230, and the pressure in the second pressure control chamber 152 changes according to Formula 4 until the internal volume of the second pressure control chamber 152 reaches its maximum value. That is, the pressure increases.

[0117] Note that in Figure 10C In this state, no ink flow occurs from the first pressure control chamber 122 to the second pressure control chamber 152 via the bypass channel 160 and the second valve chamber 151. Therefore, only the following flow exists: ink in the first pressure control chamber 122 is supplied to the ejection module 300 via the supply channel 130, and then reaches the second pressure control chamber 152 via the collection channel 140. As described above, the movement of ink from the first pressure control chamber 122 to the second pressure control chamber 152 occurs based on the pressure difference between the pressure in the first pressure control chamber 122 and the pressure in the second pressure control chamber 152. Therefore, if 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.

[0118] Furthermore, when the pressure in the second pressure control chamber 152 becomes equal to the pressure in the first pressure control chamber 122, the second pressure control chamber 152 expands to... Figure 10D The state shown. If the second pressure control chamber 152 is as indicated. Figure 10D The expansion shown forms a storage section capable of storing ink in the second pressure control chamber 152. Note that the process from stopping the circulation pump 500 to... Figure 10D The state transition, although the time frame varies depending on the shape and size of the channel and the properties of the ink. If from... Figure 10D When the circulation pump 500 is driven with ink stored in the storage compartment, the ink in the storage compartment is supplied to the first pressure control chamber 122 via the circulation pump 500. Therefore, as shown... Figure 10E As shown, the ink volume in the first pressure control chamber 122 increases, and the flexible member 230 and the pressure plate 210 shift in the expansion direction. Then, if the circulation pump 500 is continuously driven, the state in the circulation path changes, as... Figure 10A As shown.

[0119] Note that, although in the above explanation... Figure 10A An example was described as occurring during a printing operation, but as mentioned above, ink can be circulated without a printing operation. Even in this case, as... Figures 10A to 10E The ink flow shown also occurs depending on the driving and stopping of the circulation pump 500.

[0120] Furthermore, as described above, this embodiment is illustrated with the following example: when the circulation pump 500 is driving to circulate ink, the connection port 191B in the second pressure adjustment unit 150 is switched to an open state, and when ink circulation stops, the connection port 191B is switched to a closed state; however, it is not limited to this. The control pressure can be set such that even when the circulation pump 500 is driving to circulate ink, the connection port 191B in the second pressure adjustment unit 150 remains in the closed state. Hereinafter, the function of the bypass channel 160 will be described in detail.

[0121] The bypass channel 160 connecting the first pressure adjustment unit 120 and the second pressure adjustment unit 150 is installed such that, for example, if the negative pressure generated in the circulation path is stronger than a predetermined value, the injection module 300 is unaffected. Furthermore, the bypass channel 160 is also installed to supply ink to the pressure chamber 12 from both the supply channel 130 and the collection channel 140.

[0122] First, an example will be described as follows: When the negative pressure becomes stronger than a predetermined value, the ejection module 300 is unaffected because of the bypass channel 160. For example, changes in ambient temperature may alter the properties of the ink (e.g., viscosity). If the ink viscosity changes, the pressure loss in the circulation path also changes. For example, if the ink viscosity decreases, the pressure loss in the circulation path decreases. As a result, the flow rate of the circulation pump 500, driven at a constant drive amount, increases, thus increasing the flow rate in the ejection module 300. On the other hand, since the ejection module 300 is maintained at a constant temperature by a temperature adjustment mechanism (not shown), the viscosity of the ink in the ejection module 300 remains constant even if the ambient temperature changes. Although the viscosity of the ink in the ejection module 300 does not change, the increased flow rate of the ink flowing in the ejection module 300 causes the negative pressure in the ejection module 300 to increase due to flow resistance. If the negative pressure in the ejection module 300 becomes stronger than a predetermined value in this way, the meniscus of the ejection port 13 is disrupted, causing external air to be drawn into the circulation path, thus preventing normal ejection. Furthermore, even if the meniscus is not damaged, the negative pressure in pressure chamber 12 will become stronger than the predetermined pressure, which will affect the jetting.

[0123] Therefore, in this embodiment, a bypass channel 160 is formed in the circulation path. By installing the bypass channel 160, ink will still flow through the bypass channel 160 even when the negative pressure becomes stronger than a predetermined value, thus keeping the pressure in the injection module 300 constant. Therefore, for example, the connection port 191B in the second pressure adjustment unit 150 can be configured to have a control pressure that maintains a closed state even when the circulation pump 500 is being driven. Furthermore, the control pressure in the second pressure adjustment unit can be set such that when the negative pressure becomes stronger than a predetermined value, the connection port 191B in the second pressure adjustment unit 150 changes to an open state. That is, if the meniscus is not damaged, or even if the pump flow rate changes due to viscosity changes caused by environmental changes, as long as the predetermined negative pressure is maintained, the connection port 191B can remain in a closed state when the circulation pump 500 is being driven.

[0124] The following example is described: A bypass channel 160 is installed to supply ink to the pressure chamber 12 from both the supply channel 130 and the collection channel 140. Pressure fluctuations in the circulation path may also be caused by the ejection operation of the ejection element 15. This is because the ejection operation generates a force that draws ink into the pressure chamber.

[0125] The following describes the following aspects: During continuous high-load printing, the ink supplied to the pressure chamber 12 is supplied from both the supply channel 130 side and the collection channel 140 side. Note that although the definition of load may vary depending on various conditions, here, the state of printing a 4pl ink droplet on a 1200dpi grid is considered as 100%. For example, high-load printing is assumed to be printing with a load of 100%.

[0126] If high-load printing continues, the amount of ink flowing from pressure chamber 12 into the second pressure control chamber 152 through collection channel 140 decreases. On the other hand, since the circulation pump 500 discharges a constant amount of ink, the balance between inflow and outflow in the second pressure control chamber 152 is disrupted, resulting in a decrease in the amount of ink in the second pressure control chamber 152, an increase in negative pressure in the second pressure control chamber 152, and a contraction of the second pressure control chamber 152. Furthermore, as the negative pressure in the second pressure control chamber 152 increases, the amount of ink flowing into the second pressure control chamber 152 via bypass channel 160 increases, thus stabilizing the second pressure control chamber 152 in a state where outflow and inflow are balanced. Therefore, as a result, the negative pressure in the second pressure control chamber 152 increases according to the load. In addition, as described above, in a configuration where the connection port 191B is closed when the circulation pump 500 is being driven, the connection port 191B changes to an open state according to the load, so ink flows into the second pressure control chamber 152 from the bypass channel 160.

[0127] Furthermore, if high-load printing continues, the amount of ink flowing from pressure chamber 12 into the second pressure control chamber 152 through collection channel 140 decreases, while the amount of ink flowing into the second pressure control chamber 152 from connection port 191B through bypass channel 160 increases. If this state continues, the amount of ink flowing from pressure chamber 12 into the second pressure control chamber 152 through collection channel 140 becomes zero, and therefore, all the ink flowing in from connection port 191B flows out to circulation pump 500. If this state continues, ink flows back from the second pressure control chamber 152 into pressure chamber 12 through collection channel 140. In this state, the ink flowing out of the second pressure control chamber 152 to circulation pump 500 and the ink flowing out of pressure chamber 12 flow into the second pressure control chamber 152 from connection port 191B through bypass channel 160. In this case, jetting is performed by filling pressure chamber 12 with ink from supply channel 130 and collection channel 140.

[0128] Note that the ink backflow occurring under high print loads is a phenomenon caused by the installation of the bypass channel 160. Furthermore, although the example described above illustrates the connection port 191B in the second pressure adjustment unit opening in response to ink backflow, ink backflow can occur even when the connection port 191B in the second pressure adjustment unit is open. Moreover, the aforementioned ink backflow can occur even in configurations without the second pressure adjustment unit installed, due to the installation of the bypass channel 160.

[0129] <Construction of the jet unit>

[0130] Figure 11A and Figure 11B This is a schematic diagram showing the circulation path of a color ink in the spraying unit 3 of this embodiment. Figure 11A This is an exploded perspective view of the injection unit 3 as seen from the side of the first support member 4. Figure 11B This is an exploded perspective view of the jetting unit 3 as seen from the jetting module 300 side. Note that the arrows shown as "IN" and "OUT" indicate the ink flow; although only one color of ink is illustrated, other colors exhibit the same flow. Furthermore, in Figure 11A and Figure 11B The description of the second support member 7 and the electrical wiring member 5 is omitted in the preceding text, and these descriptions are also omitted in the subsequent description of the construction of the injection unit. Additionally, Figure 11A The first support member 4 shown corresponds to the one along the Figure 3A The cross-section taken from XI-XI. The spray module 300 is equipped with a spray element substrate 340 and an opening plate 330. Figure 12 The diagram shows the opening plate 330, and Figure 13 This is a diagram showing the jetting element substrate 340.

[0131] Ink is supplied from circulation unit 54 to ejection unit 3 via connecting member 8 (see Figure 3A The description refers to the channel through which ink passes through and returns to the connecting member 8. Note that the description of the connecting member 8 is omitted in the following figures.

[0132] The ejection module 300 includes an ejection element substrate 340 and an opening plate 330 constituting a silicon substrate 310, and also includes an ejection nozzle forming member 320. The ejection element substrate 340, the opening plate 330, and the ejection nozzle forming member 320 are joined in an overlapping manner, such that their respective ink channels are interconnected, thereby forming an ejection module 300 supported by a first support member 4. The ejection module 300 is supported by the first support member 4, thus forming an ejection unit 3. The ejection element substrate 340 includes the ejection nozzle forming member 320, which includes a plurality of ejection nozzles 13 forming an array, such that a portion of the ink supplied via the ink channels in the ejection module 300 is ejected from the ejection nozzles 13. Unejected ink is collected via the ink channels in the ejection module 300.

[0133] like Figure 11A , Figure 11B and Figure 12 As shown, the opening plate 330 includes multiple arrays of ink supply ports 311 and multiple arrays of ink collection ports 312. As... Figure 13 as well as Figures 14A to 14C As shown, the jetting element substrate 340 includes multiple arrays of supply connection channels 323 and multiple arrays of collection connection channels 324. Furthermore, the jetting element substrate 340 includes a common supply channel 18 communicating with the multiple supply connection channels 323, and a common collection channel 19 communicating with the multiple collection connection channels 324. By connecting the ink supply channels 48 and ink collection channels 49 (see...) mounted in the first support member 4... Figure 3A It communicates with the channel installed in the jet module 300 to form the ink channel in the jet unit 3. The support member supply port 211 is a cross-sectional opening that forms the ink supply channel 48, and the support member collection port 212 is a cross-sectional opening that forms the ink collection channel 49.

[0134] The ink supplied to the jetting unit 3 comes from the circulation unit 54 side (see...) Figure 3A The ink supply channel 48 (see) is supplied to the first support member 4. Figure 3A Ink flowing through the support member supply port 211 in the ink supply channel 48, via the ink supply channel 48 (see...) Figure 3A The ink supply port 311 of the opening plate 330 is supplied to the common supply channel 18 of the jet element substrate 340 and enters the supply connection channel 323. The channel so far is the supply-side channel. Thereafter, ink passes through the pressure chamber 12 of the jet forming member 320 (see...) Figure 3B The ink flows into the collection connection channel 324, which serves as the collection side channel. Details of the ink flow in the pressure chamber 12 will be described later.

[0135] In the collection-side channel, ink entering the collection connection channel 324 flows into the common collection channel 19. Thereafter, ink flows from the common collection channel 19 through the ink collection port 312 of the opening plate 330 to the ink collection channel 49 of the first support member 4, and passes through the support member collection port 212 to be collected by the circulation unit 54.

[0136] The area in the opening plate 330 without the ink supply port 311 and the ink collection port 312 corresponds to the area in the first support member 4 used to separate the support member supply port 211 and the support member collection port 212. Furthermore, there is no opening in the first support member 4 in this area. This area serves as the engagement area for joining the jetting module 300 and the first support member 4.

[0137] exist Figure 12 In the opening plate 330, an array of multiple openings arranged in the X direction forms multiple arrays in the Y direction, and these arrays are arranged alternately in the Y direction, such that the opening for supply (IN) and the opening for collection (OUT) are offset by half a pitch in the X direction. Figure 13 In the jetting element substrate 340, arrays of common supply channels 18 and common collection channels 19 are arranged alternately in the X direction. The array of common supply channels 18 communicates with an array of multiple supply connection channels 323 arranged in the Y direction, and the array of common collection channels 19 communicates with an array of multiple collection connection channels 324 arranged in the Y direction. The common supply channels 18 and common collection channels 19 are separate for each type of ink. Furthermore, the number of common supply channels 18 and common collection channels 19 to be arranged is determined according to the number of jetting nozzle arrays for each color. Additionally, the number of arranged supply connection channels 323 and collection connection channels 324 corresponds to the number of jetting nozzles 13. Note that a one-to-one correspondence is not necessarily required, and one supply connection channel 323 and one collection connection channel 324 can correspond to multiple jetting nozzles 13.

[0138] The aforementioned opening plate 330 and the jet element substrate 340 are joined in an overlapping manner, so that their respective ink channels are interconnected to form a jet module 300, and these ink channels, equipped with the aforementioned supply channel and collection channel, are formed by being supported by the first support member 4.

[0139] Figures 14A to 14C This is a cross-sectional view showing the ink flow in different components of the jetting unit 3. Figure 14A It is along Figure 11A A cross-sectional view taken along line XIVA-XIVA shows the section where the ink supply channel 48 and the ink supply port 311 communicate with each other in the jetting unit 3. Furthermore, Figure 14B It is along Figure 11AA cross-sectional view taken along line XIVB-XIVB shows the section where the ink collection channel 49 and the ink collection port 312 communicate with each other in the jetting unit 3. Furthermore, Figure 14C It is along Figure 11A The cross-sectional view taken along line XIVC-XIVC shows the portion of the ink supply port 311 and ink collection port 312 that is not connected to the channel of the first support member 4. Note that in Figures 14A to 14C The liquid delivery element 1001 is omitted in the text.

[0140] In the supply channel used to supply ink, such as Figure 14A As shown, ink is supplied from the portion where the ink supply channel 48 of the first support member 4 overlaps and communicates with the ink supply port 311 of the opening plate 330. Furthermore, in the collection channel for collecting ink, as... Figure 14B As shown, ink is collected from the portion where the ink collection channel 49 of the first support member 4 overlaps and communicates with the ink collection port 312 of the opening plate 330. Furthermore, as... Figure 14C As shown, the spray unit 3 includes a portion of the opening plate 330 where no opening is formed. In this region, ink is neither supplied nor collected between the spray element substrate 340 and the first support member 4. Figure 14A As shown, ink is supplied in the area forming the ink supply port 311, and as... Figure 14B As shown, ink is collected in the area where the ink collection port 312 is formed. Note that although this embodiment is described using a configuration with an opening plate 330 as an example, a configuration without an opening plate 330 may also be used. For example, a configuration may be used in which channels corresponding to the ink supply channel 48 and the ink collection channel 49 are formed in the first support member 4, and the jetting element substrate 340 is joined to the first support member 4.

[0141] Figure 15A and Figure 15B This is a cross-sectional view showing the vicinity of the injection port 13 in the injection module 300, while Figure 16A and Figure 16B This is a cross-sectional view showing an injection module as a comparative example, which has the following configuration: the common supply channel 18 and the common collection channel 19 are widened in the X direction. Note that... Figure 15A , Figure 15B , Figure 16A and Figure 16BThe thick arrows shown in the common supply channel 18 and common collection channel 19 indicate the agitation of ink when using the serial liquid jetting device 50. Ink supplied to the pressure chamber 12 through the common supply channel 18 and supply connection channel 323 is ejected from the jet nozzle 13 by the drive of the jetting element 15. When the jetting element 15 is not driven, the ink is collected from the pressure chamber 12 into the common collection channel 19 through the collection connection channel 324, which serves as a collection channel.

[0142] When using a serial liquid ejection device 50, during ink circulation and ejection, the oscillation of ink in the ink channel due to the main scanning of the liquid ejection head 1 more or less affects the ink ejection. Specifically, the effect of ink oscillation in the ink channel may manifest as a difference in ink ejection volume or a deviation in ejection direction. For example... Figure 16A and Figure 16B As shown, when the common supply channel 18 and common collection channel 19 have a wide cross-sectional shape in the X direction, which is the main scanning direction, the ink in the common supply channel 18 and common collection channel 19 is easily affected by the inertial force in the main scanning direction, which leads to significant ink agitation. As a result, the ink ejection from the ejection port 13 may be affected by ink agitation. Furthermore, if the common supply channel 18 and common collection channel 19 are widened in the X direction, the distance between colors will increase, which will reduce printing efficiency.

[0143] Therefore, in Figure 15A and Figure 15B In the two cross-sections shown, the common supply channel 18 and common collection channel 19 of this embodiment are configured to extend not only in the Y direction but also in the Z direction, which is perpendicular to the X direction (i.e., the main scanning direction). This configuration reduces the channel width of each of the common supply channel 18 and common collection channel 19 in the main scanning direction. By reducing the channel width of each of the common supply channel 18 and common collection channel 19 in the main scanning direction, ink agitation caused by inertial forces (thick black arrows in the figure) during the main scan, which act on the ink in the common supply channel 18 and common collection channel 19 in the opposite direction to the main scanning direction, is reduced. Therefore, the effect on ink ejection caused by ink agitation can be suppressed. Furthermore, by extending the common supply channel 18 and common collection channel 19 in the Z direction to increase the cross-sectional area, the pressure drop in the channels is reduced.

[0144] As described above, this configuration reduces ink sloshing in the common supply channel 18 and common collection channel 19 during the main scan by decreasing the channel width of each in the common supply channel 18 and common collection channel 19 in the main scan direction; however, sloshing is not eliminated. Therefore, in the configuration of this embodiment, in order to suppress the occurrence of jetting differences of various ink types that may still occur even after reducing sloshing, the common supply channel 18 and common collection channel 19 are arranged at an overlapping position relative to the X direction.

[0145] As described above, in this embodiment, the supply connection channel 323 and the collection connection channel 324 are installed to correspond to the ejection port 13, and the supply connection channel 323 and the collection connection channel 324 have a corresponding relationship in which they are arranged side by side in the X direction with the ejection port 13 sandwiched between them. Therefore, there are portions in which the common supply channel 18 and the common collection channel 19 do not overlap in the X direction, and if the correspondence between the supply connection channel 323 and the collection connection channel 324 in the X direction disappears, the ink flow and ejection in the pressure chamber 12 in the X direction will be affected. In addition, the ejection of ink from each ejection port may be further affected by the agitation of the ink.

[0146] Therefore, by arranging the common supply channel 18 and the common collection channel 19 in a position that overlaps with each other relative to the X direction, during the main scan, at any position in the Y direction where the ejection port 13 is arranged, the ink agitation in the common supply channel 18 and the common collection channel 19 is approximately the same. As a result, the pressure difference between the common supply channel 18 side and the common collection channel 19 side appearing in the pressure chamber 12 does not fluctuate significantly, thus enabling stable ejection.

[0147] Furthermore, in some liquid jet heads that circulate ink, the channel for supplying ink to the liquid jet head and the channel for collecting ink are constructed from the same channel; however, in this embodiment, the common supply channel 18 and the common collection channel 19 are independent channels. Moreover, the supply connection channel 323 is interconnected with the pressure chamber 12, the pressure chamber 12 is interconnected with the collection connection channel 324, and ink is ejected from the ejection port 13 of the pressure chamber 12. That is, the pressure chamber 12, serving as the channel connecting the supply connection channel 323 and the collection connection channel 324, is equipped with the ejection port 13. Therefore, an ink flow from the supply connection channel 323 side to the collection connection channel 324 side is generated in the pressure chamber 12, thus enabling efficient circulation of the ink in the pressure chamber 12. By enabling efficient circulation of the ink in the pressure chamber 12, the ink in the pressure chamber 12 (which is susceptible to evaporation from the ejection port 13) can be kept fresh.

[0148] Furthermore, since both the common supply channel 18 and the common collection channel 19 are connected to the pressure chamber 12, ink can be supplied from both channels when high-flow-rate injection is required. In other words, compared to a structure that uses only one type of channel for ink supply and collection, the structure of this embodiment not only achieves efficient circulation but also has the advantage of enabling high-flow-rate injection.

[0149] Furthermore, if the public supply channel 18 and the public collection channel 19 are arranged close to each other along the X direction, the effect of ink sloshing is unlikely. Ideally, the distance between these channels is configured to be 75 to 100 micrometers.

[0150] Figure 17 This is a diagram showing the jetting element substrate 340 as a comparative example. Note that in Figure 17 Descriptions of the supply connection channel 323 and the collection connection channel 324 are omitted. Since ink receiving heat energy from the jetting element 15 flows into the common collection channel 19 in the pressure chamber 12, ink with a relatively higher temperature than the ink in the common supply channel 18 flows in the common collection channel 19. Here, in the comparative example, a portion of the jetting element substrate 340 in the X direction contains only the common collection channel 19, such as... Figure 17 The α portion is enclosed by the dotted line. In this case, the temperature locally rises in this portion, so temperature changes occurring in the injection module 300 may affect the injection.

[0151] Compared to the common collection channel 19, ink with a relatively lower temperature flows through the common supply channel 18. Therefore, if the common supply channel 18 and the common collection channel 19 are adjacent to each other, the temperature in the common supply channel 18 and the common collection channel 19 is partially canceled out in their vicinity, thus suppressing temperature rise. Therefore, it is preferable that the common supply channel 18 and the common collection channel 19 have approximately the same length and are located at a position adjacent to and overlapping each other in the X direction.

[0152] Figure 18A and Figure 18B This diagram illustrates the channel structure of the liquid jet head 1, corresponding to the three colors of ink: cyan (C), magenta (M), and yellow (Y). (See diagram for reference.) Figure 18A As shown, in the liquid ejector head 1, circulation channels are installed for various types of ink. The pressure chamber 12 is installed along the X direction (i.e., the main scanning direction of the liquid ejector head 1). Furthermore, as... Figure 18B As shown, the common supply channel 18 and the common collection channel 19 are installed along the nozzle array where the nozzles 13 are arranged, such that the common supply channel 18 and the common collection channel 19, which extend in the Y direction, sandwich the nozzle array in the middle.

[0153] <Connection between the main body and the liquid injection head>

[0154] Figure 19 This is a schematic structural diagram that shows in more detail the connection status of the liquid ejector head 1, ink cartridge 2, and external pump 21 mounted on the main body of the liquid ejector device 50 according to this embodiment, as well as the arrangement of the circulation pump, etc. The liquid ejector device 50 according to this embodiment is configured such that if a problem occurs in the liquid ejector head 1, only the liquid ejector head 1 can be easily replaced. Specifically, it includes a liquid connection component 700, which allows easy connection and disconnection between the ink supply pipe 59 connected to the external pump 21 and the liquid ejector head 1. Therefore, only the liquid ejector head 1 can be easily attached to and removed from the liquid ejector device 50.

[0155] like Figure 19 As shown, the liquid connection component 700 includes a liquid connector inlet 53a mounted protruding from the head shell 53 of the liquid ejector head 1, and a cylindrical liquid connector 59a into which the liquid connector inlet 53a can be inserted. The liquid connector inlet 53a is fluidly connected to the ink supply channel formed in the liquid ejector head 1 and is connected to the first pressure adjustment unit 120 via the aforementioned filter 110. Furthermore, the liquid connector 59a is mounted at the front end of the ink supply tube 59 connected to an external pump 21, which pressurizes and supplies ink from the ink cartridge 2 to the liquid ejector head 1.

[0156] As mentioned above, Figure 19 The liquid injection head 1 shown can be easily attached, removed, and replaced via the liquid connection part 700. However, if the sealing performance between the liquid connector inlet 53a and the liquid connector 59a deteriorates, the ink pressurized and supplied by the external pump 21 may leak from the liquid connection part 700. If the leaked ink adheres to the circulation pump 500, etc., the electrical system may malfunction. Therefore, in this embodiment, the circulation pump, etc., is arranged as described below.

[0157] Arrangement of circulating pumps, etc.

[0158] like Figure 19As shown, in this embodiment, to prevent ink leaking from the liquid connection member 700 from adhering to the circulation pump 500, the circulation pump 500 is arranged above the liquid connection member 700 in the gravity direction. That is, the circulation pump 500 is arranged above the liquid connector inlet 53a (i.e., the liquid inlet of the liquid jet head 1) in the gravity direction. Furthermore, the circulation pump 500 is arranged in a position that does not contact the components constituting the liquid connection member 700. Therefore, even if ink leaks from the liquid connection member 700, the ink will flow horizontally (i.e., in the direction of the opening of the liquid connector 59a) or downwards in the gravity direction, thereby suppressing ink from reaching the circulation pump 500 located above in the gravity direction. Furthermore, since the circulation pump 500 is arranged away from the liquid connection member 700, the possibility of ink reaching the circulation pump 500 through the components is also reduced.

[0159] Furthermore, in the direction of gravity, an electrical connection component 515 for electrically connecting the circulation pump 500 to the electrical contact substrate 6 via the flexible wiring member 514 is mounted above the liquid connection component 700. Therefore, the possibility of electrical malfunctions due to ink from the liquid connection component 700 can be reduced.

[0160] Furthermore, in this embodiment, since the wall component 53b of the head shell 53 is installed, the ink will be blocked even if it is ejected from the opening 59b of the liquid connection component 700, thus reducing the possibility of the ink reaching the circulation pump 500 and the electrical connection component 515.

[0161] <Circulation channel in the injection module>

[0162] The features of this disclosure are described below. Figure 20A This is a partial enlarged view of the spray module 300 in this embodiment, viewed along the spray direction. Figure 20B This is a schematic cross-sectional view of the jetting module 300 of this embodiment. The jetting module 300 of this embodiment is constructed by sequentially stacking a jetting substrate 1006 forming a jetting nozzle 13, a channel member 1007 forming a channel, a first substrate 1008, and a second substrate 1009 in the Z direction. The structure of the jetting module 300 and the flow of ink in the circulation channel will be described below. Note that the arrows in the figure indicate the direction of the ink flow.

[0163] The ink ejection substrate 1006 has a plurality of ejection ports 13 for ejecting ink, and a nozzle that communicates with the ejection ports at one end and with a pressure chamber described later at the other end. The channel member 1007 is equipped with a plurality of independent channels 1002, a plurality of pressure chambers 12, and a plurality of filters 1003 installed on the ink supply side and the ink collection side. The first substrate 1008 is equipped with: an ejection element 15 for ejecting ink, a liquid delivery element 1001 for circulating ink, a supply connection channel 323, and a collection connection channel 324. The second substrate 1009 has: a common supply channel 18 communicating with the supply connection channel 323, and a common collection channel 19 communicating with the collection connection channel 324.

[0164] Multiple independent channels 1002 are channels on which the jetting substrate 1006, channel member 1007, and first substrate 1008 are formed, and are formed to extend in the X direction of the channel member 1007. The independent channels 1002 include an independent supply channel 1004 on the ink supply side and an independent collection channel 1005 on the ink collection side. The independent supply channel 1004 communicates with the supply connection channel 323. Furthermore, the independent collection channel 1005 communicates with the collection connection channel 324. Therefore, the independent channels 1002 allow ink to be supplied and circulated.

[0165] Multiple pressure chambers 12 are areas that generate energy for jetting liquid, and do not need to be chambers with clearly defined boundaries. The jetting element 15 is installed within the multiple pressure chambers 12.

[0166] A filter 1003 is installed between the supply connection channel 323 and the independent supply channel 1004. Furthermore, the filter 1003 is installed between the independent collection channel 1005 and the collection connection channel 324. Therefore, foreign objects, air bubbles, etc., can be prevented from entering the independent channel 1002.

[0167] Multiple ejection elements 15 are mounted facing the ejection nozzle 13, and an array of energy-generating elements arranged in rows at predetermined intervals in the Y direction is mounted in an independent channel 1002. The ejection elements 15 generate ejection energy for ejecting ink from the ejection nozzle 13. As described above, although an electrothermal conversion element (heater) is used as the ejection element 15 in this embodiment, a piezoelectric actuator (piezoelectric element) may also be used.

[0168] The liquid delivery element 1001 is arranged in the X direction on the side of the independent supply channel 1004, at a predetermined distance from the jetting element 15. The liquid delivery element 1001 generates heat energy to circulate ink in the independent channel 1002. If the liquid delivery element 1001 is driven, the ink is heated, and thus the ink is delivered by film boiling. Although an electrothermal conversion element (heater) is used as the liquid delivery element 1001 in this embodiment, a piezoelectric actuator (piezoelectric element) or the like can also be used. In this disclosure, the circulation of ink delivered by the liquid delivery element 1001 is referred to as micro-circulation 1011. This allows ink in the independent channel 1002 to be delivered from the independent supply channel 1004 to the independent collection channel 1005 via the pressure chamber 12. The liquid delivery element 1001 can be configured to deliver liquid when the liquid jetting device 50 is in a stopped state. The ink supplied from the circulation unit 54 passes through the common supply channel 18 and flows into the independent channel 1002 and the pressure chamber 12 via the supply connection channel 323. Furthermore, the ink supplied from the circulation unit 54 passes through the other end of the nozzle. The ink flowing into the pressure chamber 12 flows out from the common collection channel 19 via the collection connection channel 324. At this time, in this disclosure, the circulation of ink continuously supplied to the jet module 300 by the circulation unit 54 is referred to as macro-circulation 1012.

[0169] Note that the flow resistance between the liquid delivery element 1001 and the independent supply channel 1004 is denoted as R1, while the flow resistance between the liquid delivery element 1001 and the independent collection channel 1005 is denoted as R2. Since the liquid delivery element 1001 is closer to the independent supply channel 1004 than to the independent collection channel 1005, the flow resistance R1 is less than the flow resistance R2. Therefore, the bubbles generated by the drive of the liquid delivery element 1001 tend to grow towards the independent supply channel 1004. If the bubbles contract, ink flows in to fill the internal volume, so more ink flows in from the independent supply channel 1004 than from the independent collection channel 1005, causing ink to flow from the independent supply channel 1004 to the independent collection channel 1005. That is, a microcirculation 1011 occurs. The ratio of flow resistance R1 to flow resistance R2 affects the left-right ratio of the bubbles, and thus the size of the microcirculation. In this embodiment, the flow resistance ratio R1 / R2 is preferably set in the range of 0.05 to 0.4. By setting the flow resistance ratio R1 / R2 within this range, the circulating flow in the independent channel 1002 can be maintained within a suitable range. As described above, in this embodiment, the circulation unit 54 has a circulation pump 500 for circulating the liquid. A piezoelectric diaphragm pump is used as the circulation pump 500.

[0170] In this way, in the configuration of this embodiment, if ink is consumed, new ink can be supplied to the independent channel 1002. Furthermore, even when ink is not consumed, new ink can circulate within the independent channel 1002.

[0171] (Description of the drive signals for the liquid delivery element)

[0172] Figure 21 This is a diagram illustrating the jet pulses and the drive pulses of the liquid delivery element. If the head driver 1A (see...) Figure 1B When a jet pulse 1020 is applied to the jetting element 15, ink is ejected from the jetting nozzle 13, and a jet pulse pause time 1021 occurs until the next jet pulse 1020 is applied to the jetting element 15. If the head driver 1A applies a liquid delivery element drive pulse 1022 to the liquid delivery element 1001 during the jet pulse pause time 1021, the liquid delivery element 1001 is driven, thereby inducing a microcirculation 1011 in the independent channel 1002. In this embodiment, a liquid delivery element drive pulse pause time 1023 is set during the time from the jet pulse 1020 to the liquid delivery element drive pulse 1022, and during the time from the liquid delivery element drive pulse 1022 to the next liquid delivery element drive pulse 1022. After the liquid delivery element drive pulse pause time 1023, the liquid delivery element drive pulse 1022 is applied to the liquid delivery element 1001. In this embodiment, during the jet pulse pause time 1021, the liquid delivery element drive pulse pause time 1023 and the liquid delivery element drive pulse 1022 are repeated three times. In this way, by intermittently applying the liquid delivery element drive pulse 1022, the liquid in the independent channel 1002 is intermittently delivered. Thereafter, the head driver 1A (see...) Figure 1B A jet pulse 1020 is applied to the jetting element 15, causing ink to be ejected from the jetting nozzle 13. Note that in this embodiment, during the jet pulse pause time 1021, the liquid delivery element drive pulse pause time 1023 and the liquid delivery element drive pulse 1022 are repeated three times; however, this is not a limitation. Preferably, the liquid delivery element drive pulse 1022 is applied to the liquid delivery element 1001 at least once before the jet pulse 1020 is applied to the jetting element 15.

[0173] According to this disclosure, by driving the liquid delivery element 1001 in this manner, a micro-circulation 1011 can be generated within the independent channel 1002, allowing ink near the nozzle to circulate at a high flow rate only at necessary timings. On the other hand, by driving the circulation pump of the circulation unit 54, ink concentration and precipitation throughout the liquid ejector head can be suppressed at an appropriate flow rate. That is, while suppressing ink concentration and precipitation throughout the liquid ejector head, the evaporation rate of ink evaporating from the nozzle 13 can also be suppressed.

[0174] Although this disclosure has been described with reference to embodiments, it should be understood that this disclosure is not limited to the disclosed embodiments. The scope of the appended claims should be interpreted in the broadest possible sense to cover all such variations and equivalent structures and functions.

Claims

1. A liquid injection head that ejects liquid from an injection port while moving in a predetermined direction, the liquid injection head comprising: The injection unit is configured to include: The injection element is configured to generate energy for ejecting liquid from the injection port. A pressure chamber, configured to communicate with the injection port, The nozzle is configured to communicate at one end with the injection port and at the other end with the pressure chamber. An independent supply channel is configured to supply liquid to the pressure chamber. An independent collection channel is configured to collect liquid from the pressure chamber, and A liquid delivery element, disposed between the pressure chamber and the independent supply channel, and configured to deliver liquid from the independent supply channel to the independent collection channel; and A circulation unit, fluidly connected to the injection unit, is configured to circulate liquid from a common collection channel to a common supply channel, the common collection channel centrally collecting liquid from multiple independent collection channels, and the common supply channel centrally supplying liquid to multiple independent supply channels. The circulation path of the liquid formed by the circulation unit passes through the other end of the nozzle.

2. The liquid injection head according to claim 1, in, The circulation path ensures that the liquid circulates only within the liquid jet head.

3. The liquid injection head according to claim 1, in, The circulation unit includes a pump for circulating the liquid.

4. The liquid injection head according to claim 3, in, The pump is a piezoelectric diaphragm pump.

5. The liquid injection head according to claim 1, in, The liquid delivery element is an electrothermal conversion element.

6. The liquid injection head according to claim 1, in, The liquid delivery element is a piezoelectric actuator.

7. The liquid injection head according to claim 1, in, The liquid delivery element is driven intermittently to generate an intermittent flow of liquid from the independent supply channel to the independent collection channel.

8. The liquid injection head according to claim 1, in, The liquid delivery element is driven during periods when the injection element is not driven.

9. The liquid injection head according to claim 1, in, The independent supply channel, the liquid delivery element, the pressure chamber, and the independent collection channel are arranged along the predetermined direction.

10. The liquid injection head according to claim 1, in, The jetting element is an electrothermal conversion element.

11. The liquid injection head according to claim 1, in, The jetting element is a piezoelectric actuator.

12. The liquid injection head according to claim 1, in, The injection unit has a laminated structure, the laminated structure comprising: A nozzle plate, in which the injection orifice is formed. An independent channel layer, in which the pressure chamber, the independent supply channel, and the independent collection channel are formed. A component substrate, wherein the jetting element and the liquid delivery element are arranged in the component substrate, and A public channel substrate in which the public supply channel is formed.

13. A liquid injection device, comprising: The scanning unit is configured to scan the carriage in the predetermined direction. The liquid injection head according to claim 1 is mounted to the carriage; A conveying unit is configured to convey a sheet in a direction intersecting the predetermined direction, wherein droplets ejected from the liquid injection head are applied to the sheet; as well as The control unit is configured to control the scanning unit, the transport unit, the circulation unit, the injection element, and the liquid delivery element.

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