Liquid ejecting head and liquid ejecting apparatus

Abstract

The present disclosure relates to a liquid ejection head and a liquid ejection apparatus. The liquid ejection apparatus includes a printing element board, a supply flow passage and a collection flow passage, a liquid supply mechanism, and a first bubble storage unit and a second bubble storage unit. The printing element board includes a pressure chamber having an ejection port from which the printing element board ejects liquid. The supply flow passage and the collection flow passage communicate with the pressure chamber. The liquid supply mechanism generates a pressure difference between the supply flow passage and the collection flow passage to supply liquid from the supply flow passage to the pressure chamber and to recover liquid in the pressure chamber from the collection flow passage. The first bubble storage unit connects the supply flow passage to the liquid supply mechanism. The second bubble storage unit connects the collection flow passage to the liquid supply mechanism. A volume of the first bubble storage unit is greater than a volume of the second bubble storage unit.

Description

Technical Field

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

[0002] Japanese Patent Application Publication No. 2003-312006 discloses a liquid jet head that includes a fluid reservoir, a pump, a circulating flow channel, and a print head mounted on a carriage, and is configured to circulate fluid in the circulating flow channel using the pump, and to supply fluid from the fluid reservoir to the print head during a printing cycle.

[0003] However, the liquid ejector head according to Japanese Patent Application Publication No. 2003-312006 includes a separator structure for separating air and liquid from each other, and an air discharge area. Therefore, this liquid ejector head presents problems, such as increased ejector head size and ink adhesion to the separator structure. Simultaneously, air bubbles are guided to the air-liquid separator structure via an internally inclined circulation path. However, this circulation path does not pass through the interior of the pressure chamber of the printhead, which includes the nozzle that ejects the liquid. In other words, according to the technology of Japanese Patent Application Publication No. 2003-312006, there is no fluid circulation within the pressure chamber. As a result, there is a risk of ejection errors, for example, if air bubbles or the like enter the pressure chamber. Summary of the Invention

[0004] The applicant's disclosure provides a liquid injection head and a liquid injection device that suppresses the occurrence of injection errors without increasing the size of the device.

[0005] According to one aspect of this disclosure, a liquid jetting apparatus includes: a printing element board including a pressure chamber with a jet nozzle, wherein the printing element board is configured to jet liquid from the jet nozzle; a supply flow channel disposed on the printing element board and communicating with the pressure chamber; a collection flow channel disposed on the printing element board and communicating with the pressure chamber; a liquid supply mechanism configured to generate a pressure difference between the supply flow channel and the collection flow channel, thereby supplying liquid from the supply flow channel to the pressure chamber and recovering liquid from the pressure chamber from the collection flow channel; a first bubble storage unit connecting the supply flow channel to the liquid supply mechanism; and a second bubble storage unit connecting the collection flow channel to the liquid supply mechanism, wherein the volume of the first bubble storage unit is larger than the volume of the second bubble storage unit.

[0006] According to this disclosure, a liquid jetting head and a liquid jetting device can be provided that can suppress the occurrence of jetting errors without increasing the size of the device.

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

[0008] Figure 1 It is a schematic perspective view of a liquid jetting device that can utilize liquid jetting heads;

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

[0010] Figure 3 An exploded perspective view of the liquid injection head;

[0011] Figure 4 This is a schematic diagram illustrating the cyclic path for a single ink color in a steady state.

[0012] Figure 5A It is a cross-sectional view of the printed component board taken at a specific position in the y-direction;

[0013] Figure 5B These are cross-sectional views of the printed component board taken at different positions along the y-direction;

[0014] Figure 5C This is a cross-sectional view of the printed component board taken at a different location in the y-direction;

[0015] Figure 6 A diagram illustrating ink flow when printing using most of the nozzles;

[0016] Figure 7 To show a side view of the liquid injection head;

[0017] Figure 8A To show a cross-sectional view of the liquid injection head;

[0018] Figure 8B To show another cross-sectional view of the liquid injection head;

[0019] Figure 9 A schematic diagram illustrating the internal workings of the loop unit;

[0020] Figure 10A A cross-sectional view showing the first ink connection flow channel and the second ink connection flow channel;

[0021] Figure 10B This is another cross-sectional view showing the first ink connection flow channel and the second ink connection flow channel;

[0022] Figure 11A A schematic diagram illustrating the circulating flow channel;

[0023] Figure 11B To illustrate another schematic diagram of the circulating flow channel;

[0024] Figure 12A A diagram illustrating ink flow and bubble behavior when using multiple nozzles;

[0025] Figure 12B Another diagram illustrating ink flow and bubble behavior when using multiple nozzles;

[0026] Figure 13A A cross-sectional view is shown for illustrating the first bubble storage unit and the second bubble storage unit;

[0027] Figure 13B To show another cross-sectional view of the first bubble storage unit and the second bubble storage unit;

[0028] Figure 14 For along Figure 13A A cross-sectional view taken by the XIV-XIV line;

[0029] Figure 15 For along Figure 7 A cross-sectional view taken along the XV-XV line;

[0030] Figure 16A A schematic diagram illustrating the circulating flow channel;

[0031] Figure 16B This is another schematic diagram showing the circulating flow channel;

[0032] Figure 17A A diagram illustrating an example of a pressure regulating unit;

[0033] Figure 17B Another diagram showing an example of a pressure regulating unit;

[0034] Figure 17C Another diagram showing an example of a pressure regulating unit;

[0035] Figure 18A External perspective view of the circulating pump;

[0036] Figure 18B Another external perspective view of the circulating pump;

[0037] Figure 19 This is a cross-sectional view of the circulating pump along line XIX-XIX;

[0038] Figure 20A A diagram used to explain the flow of ink in a liquid jet nozzle;

[0039] Figure 20B Another diagram used to explain the flow of ink in a liquid jet nozzle;

[0040] Figure 20C This is another diagram used to explain the flow of ink in a liquid jet nozzle;

[0041] Figure 20DThis is another diagram used to explain the flow of ink in a liquid jet nozzle;

[0042] Figure 20E Another diagram used to explain the flow of ink in a liquid jet nozzle;

[0043] Figure 21A A schematic diagram illustrating the circulation path for one ink color in a jetting unit;

[0044] Figure 21B Another schematic diagram illustrating the circulation path for one ink color in the injection unit;

[0045] Figure 22 A diagram showing the opening plate;

[0046] Figure 23 A diagram showing the injection element plate;

[0047] Figure 24A A cross-sectional view showing the ink flow at a specific part of the jetting unit;

[0048] Figure 24B A cross-sectional view showing ink flow at different parts of the jetting unit;

[0049] Figure 24C A cross-sectional view showing ink flow at another different part of the jetting unit;

[0050] Figure 25A A cross-sectional view showing the portion near the injection nozzle in the injection module;

[0051] Figure 25B To show another cross-sectional view of the portion near the injection port in the injection module;

[0052] Figure 26 A diagram showing a comparative example of the injection element plate;

[0053] Figure 27A A diagram illustrating the flow channel structure of a liquid jet head suitable for three colors of ink;

[0054] Figure 27B Another diagram illustrating the flow channel configuration of a liquid jet head suitable for three colors of ink; and

[0055] Figure 28 This diagram illustrates the connection between the liquid jet head, the ink tank, and the external pump. Detailed Implementation

[0056] (First Embodiment)

[0057] The first embodiment of this disclosure will now be described with reference to the accompanying drawings.

[0058] Figure 1This is a schematic perspective view of a liquid jetting apparatus 2000 that can utilize the liquid jetting head 1000 according to this embodiment. The liquid jetting apparatus 2000 of this embodiment is a serial scanning type inkjet printing apparatus configured to print images on a printing medium P by jetting liquid (hereinafter also referred to as ink) from liquid jetting heads 1000 and 1001. Liquid jetting heads 1000 and 1001 can be mounted on a carriage 10, and the carriage 10 is configured to be movable along a guide shaft 11 in the main scanning direction (i.e., the x-direction). The printing medium P is conveyed in a vertical scanning direction, which is the y-direction intersecting (perpendicular to) the main scanning direction, using a transfer roller (not shown).

[0059] Two types of liquid ejector heads are mounted on carriage 10. Liquid ejector head 1000 can eject three types of ink, while liquid ejector head 1001 can eject six types of ink. Ink is pressurized from nine types of ink tanks (liquid tanks) 2 (21, 22, 23, 24, 25, 26, 27, 28, and 29) through ink supply pipes 30 to the liquid ejector heads. A supply pump for pressurized supply, which will be described later, is mounted on ink supply unit 12.

[0060] As a modification, by setting the three types of ink in the liquid jet head 1000 to the same type of ink, the ink tank can be reduced to seven types, or by installing one or more additional liquid jet heads, the liquid jetting device can be configured to jet twelve or more types of ink.

[0061] The liquid jet head 1000 is fixed to and supported by the carriage 10 using the positioning unit and electrical contacts of the carriage 10. The liquid jet head 1000 performs printing by jetting ink while moving in the scanning direction (x direction).

[0062] Figure 2 This is a perspective view of the liquid injection head 1000 in this embodiment. Figure 3 This is an exploded perspective view of the liquid ejector head 1000. The liquid ejector head 1000 includes a printing element unit 100, a circulation unit 200, a head housing unit 300, and a cover 502. The printing element unit 100 includes a printing element plate 110, a support member (flow channel member) 102 connected to the printing element plate 110 and provided with an ink supply connection flow channel 310 and an ink collection connection flow channel 320, a cable tie 103, and an electrical contact plate 104. The electrical contact plate 104 includes electrical contact points that contact the carriage 10 and supplies signals and energy for driving the circulation pump 203 mounted on the circulation unit 200 via a circulation unit connector 106 and a pump line (not shown). Furthermore, the electrical contact plate 104 supplies driving signals and energy for ink ejection to the printing element plate 110 via the cable tie 103.

[0063] Electrical connection modules are implemented using anisotropic conductive films (not shown), wire bonding, solder mounting, etc. However, the connection methods are not limited to these methods. In this embodiment, the connection between the printed component board 110 and the wire strip 103 is achieved through wire bonding. The electrical connection module is sealed with a sealing material to protect it from ink corrosion and external impacts.

[0064] The circulation unit 200 includes a first pressure regulating mechanism 201 and a second pressure regulating mechanism 202 (see below). Figure 4 The circulation pump 203, the first pressure regulating mechanism 201, and the second pressure regulating mechanism 202 can regulate the pressure in the circulation path. Ink flows through the ink supply tube 30 (see...). Figure 1 The ink supply channel is formed by fixing the circulation unit 200 to the head housing unit 300, which is equipped with a tube connector 31, from the ink tank 2 to the ink supply port 32. In this embodiment, the ink supply channel is formed by fixing the circulation unit 200 to the head housing unit 300 using screws 501.

[0065] Elastic components such as rubber and elastomers are used as sealing components in the connectors of each ink supply channel. The print element unit 100 is attached and secured to the head housing unit 300, thereby forming the ink supply channel. The elastic component can be used in the connectors of the ink supply channel. The head housing unit 300 is formed from a combination of parts obtained by injection molding of filler resin to achieve positioning relative to the carriage 10 and to form the shape of the ink flow channel.

[0066] The printing element board 110 is provided with columns of nozzles by arranging the nozzles in the y-direction. Multiple columns of nozzles are arranged in the x-direction.

[0067] Figure 4 For illustrative purposes, the diagram shows a stable circulation path for one ink color in the liquid jetting device 2000 applied in this embodiment. Ink is pressurized from the ink tank 21 to the liquid jetting head 1000 using a supply pump P0. Dust and other contaminants are removed from the ink using a filter 204, and then the ink is supplied to the first pressure regulating mechanism 201. Figure 4 (and will be described later) Figure 6 In the diagram, the first pressure regulating mechanism 201 is marked with "L", while the second pressure regulating mechanism 202 is marked with "H". Here, "H" represents high negative pressure, and "L" represents low negative pressure, which is the opposite of high and low levels based on positive pressure. The first pressure regulating mechanism 201 regulates the pressure in the first pressure control chamber 211 to a predetermined pressure (negative pressure). The circulation pump 203 is a piezoelectric diaphragm pump, which is configured to change the volume inside the pump chamber by inputting a drive voltage to a piezoelectric element attached to the diaphragm, and to supply liquid by alternately activating two check valves as the pressure changes.

[0068] A circulation pump 203 supplies ink from a second pressure control chamber 221 on the low-pressure (high negative pressure) side to a first pressure control chamber 211 on the high-pressure (low negative pressure) side. The pressure in the second pressure control chamber 221 is regulated by a second pressure regulating mechanism 202 to a pressure lower than that in the first pressure control chamber 211. Multiple pressure chambers 113, each with a nozzle capable of ejecting liquid, are disposed on the print element board 110. A common supply flow channel 111 and a common collection flow channel 112 are connected to the respective pressure chambers 113.

[0069] Each common supply flow channel 111 is connected to the first pressure control chamber 211 via a first ink connection flow channel 310, and the pressure in the common supply flow channel 111 is thus regulated to the high-pressure (upstream) side. Each common collection flow channel 112 is connected to the second pressure control chamber 221 via a second ink connection flow channel 320, and the pressure in the common collection flow channel 112 is thus regulated to the low-pressure (downstream) side. Due to the pressure difference between the common supply flow channel 111 and the common collection flow channel 112, pressure is generated in each pressure chamber 113 along the pressure difference. Figure 4 The flow is in the direction of the middle arrow α. A portion of the ink with increased viscosity is recovered from pressure chamber 113; this portion is present near each ejector nozzle when it is in standby mode or not ejecting ink during printing operations. Therefore, ejection errors can be suppressed.

[0070] In this embodiment, a first bubble storage unit 301 is disposed in a first ink connection flow channel 310, and a second bubble storage unit 302 is disposed in a second ink connection flow channel 320. Each of the first bubble storage unit 301 and the second ink connection flow channel 320 has a volume that can temporarily store bubbles generated during printing operations or during printing standby within the ink path.

[0071] Figures 5A to 5C This is a cross-sectional view of the printing element board 110 taken at different positions along the y-direction. The printing element board 110 includes a Si substrate 120 and an ejector assembly 130. Circuitry (not shown) and a heater 115, serving as a pressure generating mechanism, are disposed on the Si substrate 120. Pressure chambers 113 and ejector nozzles 114 corresponding to the heaters 115 are patterned in the ejector assembly 130 using photolithography. Although this embodiment is configured to obtain ejection energy by generating ink bubbles in each pressure chamber 113 by applying voltage to the corresponding heaters 115, the pressure generating mechanism is not limited to this configuration. Piezoelectric elements can be used instead of heaters. The printing element board 110 is stacked on a support member 102, and the Si substrate 120 includes a contact surface 123. The contact surface 123 is attached and fixed to the support member 102, thereby connecting to the corresponding ink supply channels.

[0072] In this embodiment, the distance between the common supply flow channel 111 and the common collection flow channel 112 in the x-direction is set to a spacing of 1 mm or less to ensure ink supply performance to the pressure chamber 113 and to reduce costs by decreasing the substrate size. Simultaneously, from the perspective of dotting efficiency on the printing medium P, four nozzle rows are deployed, each with nozzles arranged at 600 dpi. Note that the resolution of the nozzle deployment and the number of nozzle rows are not limited to the examples described above.

[0073] Figure 5A A cross-section of the opening 121 of the public supply flow channel 111 is shown at the location where the public supply flow channel 111 communicates with the contact surface 123. Figure 5B A cross-section is shown at a location where neither the public supply flow channel 111 nor the public collection flow channel 112 communicates with the contact surface 123. Figure 5C A cross-section of the common collection flow channel opening 122 is shown at the location where the common collection flow channel 112 communicates with the contact surface 123.

[0074] To control the pressure difference between each common supply flow channel 111 and its corresponding common collection flow channel 112, it is necessary to separate the ink supply channels except for the pressure chamber 113 and the pressure control mechanism. Therefore, the first ink connection flow channel 310 and the second ink connection flow channel 320 need to be separated. Figure 5B The cross-sectional locations shown are separated along the direction of the jet nozzle array. Each of the common supply flow channel 111 and the common collection flow channel 112 has a very small cross-sectional area, thus posing a risk of insufficient ink supply due to pressure losses associated with the liquid supply. Therefore, it is desirable to form the shortest possible cross-sectional area. Figure 5B The diagram shows a common supply flow channel 111 and a common collection flow channel 112 that are not connected to the contact surface 123. Therefore, it is desirable to have multiple such channels in the direction of the injection nozzle array. Figure 5A The public supply flow channel opening 121 and multiple such as Figure 5C The public collection flow channel opening 122 is shown.

[0075] exist Figure 3 In the exploded perspective view, the first ink connecting flow channel 310 for one color is arranged in nine positions, and the second ink connecting flow channel 320 for the same color is arranged in eight positions. The number of these connecting positions varies depending on the length of the nozzle array and the spacing between the connecting points. In this embodiment, Figure 5B The cross-sectional area of ​​each public supply flow channel 111 and each public collection flow channel 112 is equal to or less than 0.1 mm². 2 Furthermore, the distance between each public supply flow channel opening 121 and the corresponding public collection flow channel opening 122 is equal to or less than 7.5 mm.

[0076] Figure 6 The diagram illustrates the ink flow in a circulation path for a single color when printing is performed using most of the nozzles. Unlike the flow pattern in a steady-state circulation scenario, when printing is performed using most of the nozzles, ink is supplied from both the common supply flow channel 111 and the common collection flow channel 112 to the corresponding pressure chamber 113.

[0077] When ink is ejected from a specific pressure chamber 113, ink is supplied from each of the common supply flow channel 111 and the common collection flow channel 112. The common supply flow channel 111 supplies ink from the first pressure control chamber 211 through the first ink connection flow channel 310 to the corresponding pressure chamber 113. Simultaneously, the common collection flow channel 112 supplies ink from the second pressure control chamber 221 through the second ink connection flow channel 320 to the corresponding pressure chamber 113. The circulation pump 203 delivers ink from the second pressure control chamber 221 to the first pressure control chamber 211 in the same manner as in the steady state.

[0078] In this configuration, the second pressure control chamber 221 supplies ink to the second ink connection flow channel 320 and the circulation pump 203. Furthermore, the second pressure control chamber 221 maintains a constant pressure by supplying ink from the first pressure control chamber 211 via a bypass flow channel that connects the first pressure regulation mechanism 201 to the second pressure regulation mechanism 202. When the first pressure control chamber 211 supplies ink to the second pressure regulation mechanism 202 and the first ink connection flow channel 310, the first pressure control chamber 211 maintains a constant pressure by recovering ink from the ink tank 21, which serves as the ink source, and from the portion of ink delivered by the circulation pump 203.

[0079] As described above, the ink flow direction in the common collection flow channel 112 changes according to the printing state, and consequently the ink flow direction in the second ink connection flow channel 320 changes.

[0080] Figure 7 A side view of the liquid injection head 1000 is shown. Figure 8A It is along Figure 7 A cross-sectional view taken along line VIIIA-VIIIA. Figure 8B It is along Figure 7 The cross-sectional view is taken along line VIIIB-VIIIB. The printing element plate 110 is provided with a row of ejector nozzles along the y-direction, which is the direction of movement of the printing medium P, and ink is ejected from each ejector nozzle in the z-direction. The first ink connection flow channel 310 and the second ink connection flow channel 320 are formed by the head housing unit 300 and the support member 102.

[0081] The printing element board 110 is supported by the support member 102. The printing element board 110 is supported to establish a connection from the first pressure control chamber 211 through the first ink connection flow channel 310 to the common supply flow channel opening 121 and the common supply flow channel 111. Simultaneously, the printing element board 110 is supported to establish a connection from the second pressure control chamber 221 through the second ink connection flow channel 320 to the common collection flow channel opening 122 and the common collection flow channel 112, as... Figure 8B As shown.

[0082] The first pressure control chamber 211 and the second pressure control chamber 221 are controlled at a constant pressure by using a pressure regulating mechanism built into the circulation unit 200.

[0083] Figure 9 This is a schematic diagram illustrating the interior of the circulation unit 200. In the circulation unit 200, ink is supplied under pressure from the ink supply unit 12 through the ink supply port 32 and the filter 204 to the first pressure regulating mechanism 201. The pressure regulating mechanism 201 includes a valve 232, a valve spring 233, a flexible member 231, a pressure plate 235, and a pressure regulating spring 234.

[0084] In the pressure control chamber 211, when the volume of the pressure control chamber 211 decreases due to ink discharge or other reasons, the pressure plate 235 deforms the flexible member 231 and the pressure regulating spring 234, thereby attempting to maintain a constant pressure within the pressure control chamber 211. Through the compression deformation of the pressure regulating spring 234, the valve spring 233 deforms in the compression direction via the valve 232. Therefore, the valve 232 can be opened to supply ink to the pressure control chamber 211. This behavior enables ink supply and maintains a constant pressure within the pressure control chamber 211. The negative pressure in the pressure control chamber 211 is set according to the contact position between the pressure regulating spring 234 and the valve 232 and the pressure plate 235.

[0085] The pressure regulating mechanism 202 of the pressure control chamber 221 includes a valve 242, a valve spring 243, a flexible component 241, a pressure plate 245, and a pressure regulating spring 244. The pressure regulating principle in the pressure regulating mechanism 202 is the same as that applicable to the pressure regulating mechanism 201, the only difference being that the ink supply source is changed from the ink supply unit 12 to the pressure control chamber 211.

[0086] The circulation pump 203 is connected to supply ink from the pressure control chamber 221 to the pressure control chamber 211. In this embodiment, a small diaphragm pump using a piezoelectric element is employed as the circulation pump 203. Since the pump can be driven by applying voltage pulses to the piezoelectric element, the circulation pump 203 can be controlled to open and close using the input voltage pulses. By using the circulation pump 203 to deliver ink from the pressure control chamber 221 to the pressure control chamber 211, the pressure control chamber 211 is set to apply a pressure equivalent to the amount of ink supplied, and the pressure control chamber 221 is set to a negative pressure state, the amount of which is equivalent to the amount of ink supplied.

[0087] When the pressure control chamber 221 is set to negative pressure, the pressure control chamber 221 recovers ink through the pressure regulating mechanism 202. On the other hand, the pressure regulating mechanism 202 recovers ink from the pressure control chamber 211 and the pressure chamber 113, thus generating a circulating flow while maintaining a constant pressure. Since the circulating flow through the pressure chamber 113 is generated as described above, ink with increased viscosity due to ink evaporation near the nozzle can be removed, thereby achieving stable ejection.

[0088] Figure 10A To illustrate the cross-sectional view of the first ink connection flow channel 310 connected to the pressure control chamber 211 in this embodiment, Figure 10B This is a cross-sectional view showing the second ink flow channel 320 connected to the pressure control chamber 221. The printing element board 110 includes an ejector member 130 and a Si substrate 120. A heating heater (not shown) for stabilizing ejection is provided on the Si substrate 120. Meanwhile, to ensure uniform temperature across the entire printing element board 110 and achieve stable bonding with the Si substrate 120, the support member 102 is made of alumina material with high thermal conductivity and a linear expansion coefficient close to that of Si.

[0089] exist Figure 10A and 10B In the diagram, the arrows (solid lines) in the flow channel indicate the flow of ink circulated by the driving circulation pump 203 when printing is not performed. More precisely, in Figure 10AIn the process, ink flows from pressure control chamber 211 to common supply flow channel opening 121, simultaneously passing through the first ink connection flow channel 310 formed by the head housing unit 300 including the first bubble storage unit 301 and the support member 102. This ink flow begins from common supply flow channel 111, passes through ink jet pressure chamber 113, flows to common collection flow channel 112, and is then recovered from common collection flow channel opening 122. Furthermore, the second ink connection flow channel 320, formed by the head housing unit 300 including the second bubble storage unit 302 and the support member 102, supplies the ink recovered from common collection flow channel opening 122 to pressure control chamber 221. Subsequently, circulation pump 203 supplies ink from pressure control chamber 221 to pressure control chamber 211. Thus, one cycle of circulation is achieved.

[0090] Figure 11A To illustrate the circulating flow channel in inkjet mode, Figure 11B This is a schematic diagram illustrating a circulating flow channel in the case of continuous circulation for a period of time without the generation of bubbles. The circulating flow is completed within the ink flow channel of the liquid ejector head 1000. Therefore, bubbles 500 generated within the flow channel of the liquid ejector head 1000 should be present somewhere in the circulating flow, including the first pressure control chamber 211 and the second pressure control chamber 221. Bubbles 500 are generated by: foaming during ink filling, the flow of ink, etc.; supersaturation of gases dissolved in the ink associated with a rise in temperature or a decrease in pressure inside the liquid ejector head 1000; and so on. If bubbles 500 flow into any pressure chamber 113, they tend to cause ink ejection errors, which may lead to image errors. Therefore, it is desirable to store these bubbles 500 in a portion of the circulating flow channel away from the pressure chamber 113 to prevent bubbles 500 from flowing into the pressure chamber 113.

[0091] In the case of a conventional liquid jet head that does not have a section in its flow channel for storing air bubbles, it is necessary to use the liquid jet head within a range where dissolved gases will not cause supersaturation, while controlling the degree of ink degassing, or removing the generated air bubbles from the liquid jet head each time they are generated. Methods for controlling the degree of degassing exist, including agitation under reduced pressure and degassing modules using hollow fiber membranes. However, these methods can lead to high costs and increases in head size and weight, which may adversely affect printing speed and other performance characteristics. On the other hand, in each case where ink containing air bubbles is discharged, the ink that should have been used for printing is discharged as waste ink. Therefore, this approach increases printing costs.

[0092] In view of the above, in this embodiment, as Figure 11AAs shown, the first bubble storage unit 301 and the second bubble storage unit 302 are located in the circulating flow channel away from the pressure chamber 113 to collect the generated bubbles 500 in the first bubble storage unit 301 and the second bubble storage unit 302. In this way, bubbles 500 can be prevented from flowing into the pressure chamber 113, thereby reducing the chance of causing ejection errors. By reducing the occurrence of ejection errors according to the above method, a significant increase in head size or an increase in waste ink can be suppressed.

[0093] Since the circulating flow during printing is not performed, ink flow from the print element plate 110, including the pressure chamber 113, toward the second bubble storage unit 302 is generated in the second ink connection flow channel 320. Therefore, bubbles 500 accumulate in the second bubble storage unit 302 due to the ink flow. On the other hand, ink flow directed toward the print element plate 110 is generated in the first ink connection flow channel 310. Therefore, it is difficult for bubbles 500 to accumulate in the first bubble storage unit 301.

[0094] In this embodiment, the top surface of the first ink connection flow channel 310 has an angle (θ11 and θ13) of approximately 40 to 50 degrees relative to the surface where the injection nozzle is located (see...). Figure 10A Here, the top is a surface that defines a portion of the flow channel, corresponding to the inner wall of the flow channel, wherein the component of the normal vector at the top surface has a component in the direction of gravity (z direction).

[0095] According to the above configuration, even when ink flow is generated towards the printing element plate 110, the bubbles 500 are easily guided to the first bubble storage unit 301, so that the bubbles 500 can accumulate at a position away from the pressure chamber 113. These angles θ are determined based on the coefficient of friction defined by the physical properties of the inner wall of the ink and the first ink connecting flow channel 310 and the migration force caused by buoyancy.

[0096] It has been confirmed that by making the top surface at an angle of about 15 degrees or greater relative to the surface with the nozzle, the ink used in the liquid jet head 1000 and the first ink connection flow channel 310 in this embodiment successfully achieves the effect of this embodiment. More preferably, each top surface is set at an angle close to 90 degrees, whereby 100% of the buoyancy component of each bubble 500 can be used for migration force.

[0097] Furthermore, in this embodiment, the top surface of the second ink connecting flow channel 320 has an angle (θ22 and θ24) in the range of approximately 40 to 50 degrees relative to the surface provided with the injection nozzle in this embodiment (see...). Figure 10BTherefore, the movement of bubble 500 to the second bubble storage unit 302 can be accomplished in a short time by using the circulating flow pressure in addition to the migration force caused by buoyancy.

[0098] Simultaneously, by utilizing the circulating flow, the bubbles 500 accumulated in the second bubble storage unit 302 are gradually moved from the second bubble storage unit 302 to the first pressure regulating chamber 211 and the first bubble storage unit 301 (see second pressure regulating chamber 221 and circulation pump 203) through the second pressure regulating chamber 221 and circulation pump 203. Figure 11B As described above, when the bubble 500 moves towards the supply flow channel downstream of the circulating pump, it is also necessary to prevent the bubble 500 in the first bubble storage unit 301 from reaching the pressure chamber 113. To this end, it is desirable to ensure a sufficiently large volume for storing the bubble 500 by setting the volume downstream of the circulating pump 203 to be larger than the volume of the flow channel upstream of the circulating pump 203.

[0099] Meanwhile, in the circulation channel, the first pressure control chamber 211 and the second pressure control chamber 221 can change their volumes to achieve pressure control. Therefore, it is desirable to provide bubble storage units of a certain volume in separate locations. In this embodiment, a first bubble storage unit 301 and a second bubble storage unit 302 are provided, and the volumes of these units are set to satisfy the relationship (volume of the first bubble storage unit 301) > (volume of the second bubble storage unit 302).

[0100] Here, the larger the flow channel volume, the greater the capacity to store 500 air bubbles. However, arbitrarily increasing the overall volume may lead to an increase in head size or the required ink volume. Meanwhile, in the case of complex flow channel shapes with a specific volume of space, there is a filling method called choke suction, which is designed to perform ink filling by releasing the ink supply valve after reducing the pressure to a specific pressure, thereby filling the space with ink in the anti-gravity direction as well.

[0101] Although this embodiment also employs choke suction, this filling method still results in gas remaining at a certain percentage of the total flow channel volume. Consequently, the expansion of the flow channel volume also leads to an increase in the initial gas quantity. Therefore, a larger flow channel volume is not always ideal, and factors such as pressure loss, initial gas quantity, and gas production volume need to be considered when determining the total flow channel volume and the volume difference between the upstream and downstream of the circulating pump.

[0102] In this embodiment, the volume downstream of the pump (from the pump outlet to the injection port) is approximately 6.4 cc, while the volume upstream of the pump (from the injection port to the pump inlet) is approximately 4.2 cc. Here, the volume downstream of the pump is almost 1.5 times the volume upstream of the pump. These volumes create a volume difference when the first and second pressure regulating chambers, the first and second ink connecting flow channels, and the flow channels connecting these components to each other are added together. In other words, the relationship that "the volume of the first pressure regulating chamber (211) > the volume of the second pressure regulating chamber (221)" holds true, and the relationship that "the volume of the first ink connecting flow channel (310) > the volume of the second ink connecting flow channel (320)" holds true.

[0103] Due to the residual gas from the initial ink filling and the gas generated associated with continuous jetting, approximately 20% of the total ink volume remains even if the entire volume upstream of the pump is vaporized and moves downstream. The initial ink fill rate depends on the product specifications, which in turn depend on the pressure loss during filling and the number of pumping cycles. The amount of gas generated due to jetting varies depending on the ink type and temperature. Furthermore, the timing of gas venting also depends on the product specifications. Therefore, it is impossible to determine a minimum volumetric efficiency overall. However, it is necessary to set the volume downstream of the pump to be at least approximately 1.2 times the volume upstream of the pump to ensure at least 10% ink retention.

[0104] In this embodiment, the pump is installed inside the liquid ejector head 1000. This is a particularly effective configuration because the method for removing gas from the flow channel is limited to suction from the ejector port. However, this embodiment is not limited to a configuration where the circulating flow channel is completed inside the liquid ejector head. For example, it is acceptable to install a circulating pump outside the liquid ejector head (in the printing device body, etc.) or to not install a gas removal unit. Even in the above configuration, in order to reduce the frequency of gas removal operations, it is effective to set the "volume from the outlet of the circulating pump to the supply port of the printhead and print element board" to be greater than the "volume from the collection port of the printhead and print element board to the inlet of the circulating pump".

[0105] Simultaneously, since the volume of the first ink connection flow channel 310 is set to be larger than the volume of the second ink connection flow channel 320, the flow velocity of the ink flowing in the first ink connection flow channel 310 becomes lower than the flow velocity of the ink flowing in the second ink connection flow channel 320. By reducing the ink flow velocity, the air bubbles 500 in the first ink connection flow channel 310 easily detach from the pressure chamber 113 due to buoyancy. Furthermore, by setting the volume of the second ink connection flow channel 320 to be smaller than the volume of the first ink connection flow channel 310, the flow velocity of the ink flowing in the second ink connection flow channel 320 becomes faster than the flow velocity of the ink flowing in the first ink connection flow channel 310. By increasing the ink flow velocity, the air bubbles 500 in the second ink connection flow channel 320 easily detach from the pressure chamber 113 due to buoyancy and the ink flow velocity.

[0106] Figure 12A and 12B For use Figure 6 The diagram shows the flow of ink and the behavior of bubbles 500 in most nozzle conditions. Figure 12A This is a cross-sectional view showing the first ink connection flow channel 310 connected to the pressure control chamber 211. Figure 12B This is a cross-sectional view showing the second ink connection flow channel 320 connected to the pressure control chamber 221. Figure 12A and 12B The cross-sectional position and Figure 10A and 10B The same as in [the previous sentence].

[0107] When printing is performed using most of the nozzles, compared to Figure 10A and 10B In the non-printing state shown, a larger amount of ink in the circulating flow is supplied to the pressure chamber 113, thereby generating a large ink flow in each flow channel. Simultaneously, when printing is performed using most of the nozzles, the circulating flow of ink in each of the first ink-connecting flow channel 310 and the second ink-connecting flow channel 320 is directed towards the pressure chamber 113. Due to the increased ink flow rate, the overall ink flow velocity increases in the direction towards the pressure chamber 113.

[0108] Specifically, in the first ink-connecting flow channel 310 and the second ink-connecting flow channel 320 formed by the support member 102, the cross-sectional area of ​​each flow channel is relatively small, resulting in a rapid flow rate and an increased dynamic pressure applied to the bubbles 500, making it more likely that the bubbles 500 will flow into the pressure chamber 113. Meanwhile, in this embodiment, the jetting energy in each pressure chamber 113 is generated using thermal energy from the heater 115. Therefore, the temperature of the printing element plate 110 increases with jetting. As a result, the interior of the circulating flow channels formed in the support member 102 and the printing element plate 110 reaches a relatively high temperature, and the gas dissolved in the ink is more likely to become supersaturated and readily generate bubbles 500.

[0109] When printing is performed using most of the nozzles described above, the bubble 500 must be moved to the first bubble storage unit 301 or the second bubble storage unit 302 by periodically establishing a cycle state when printing is not performed or by stopping the cycle according to the ink ejection volume or ejection cycle. This period of moving the bubble 500 may involve printing pauses as described above, and may therefore reduce printing productivity. Therefore, it is desirable to set each top surface at an angle close to 90 degrees, at which 100% of the buoyancy component of the bubble 500 can be used as a migration force in order to reduce the period of moving the bubble 500.

[0110] As a modification example, there is a case where a heater is mounted on the printed element board 110 to regulate the ink temperature, and a resin material with low thermal conductivity can be used for the support member 102, while also considering the temperature regulation rate. In this case, the location where bubbles are generated by heat is limited to a portion near the Si substrate 120.

[0111] Meanwhile, the common supply flow channel 111 provided in the printing element board 110 is formed according to Si substrate processing technology. For this reason, it is difficult to ensure a sufficient angle relative to the surface where the nozzle is provided. In addition, since the cross-sectional area of ​​each flow channel is very small, it is difficult to guide the bubbles 500 to the first bubble storage unit 301 by utilizing buoyancy against the circulating flow. Therefore, depending on the ink ejection volume and printing cycle, it is necessary to regularly discharge the bubbles 500 generated in the common supply flow channel 111 through the nozzle through the pressure chamber 113 by means of suction or the like. Nevertheless, the volume of ink in the common supply flow channel 111 is very small, thereby minimizing the amount of waste ink.

[0112] Figure 13A To show a cross-sectional view of the first bubble storage unit 301 when storing a large number of bubbles 500, Figure 13B A cross-sectional view of the second bubble storage unit 302 when storing a large number of bubbles 500 is shown. Figure 13A and 13B The cross-sectional position and Figure 10A and 10B The same as in [the previous sentence]. Figure 14 It is along Figure 13A The cross-sectional view taken along line XIV-XIV shows the slits 303 in the first bubble storage unit 301 and the second bubble storage unit 302. When the bubbles 500 combine with each other to substantially block the dimensions of the flow channel cross-section, the bubbles 500 drift into the pressure chamber 113 due to the increased drag caused by the ink flow.

[0113] However, the cross-sectional area (including its top) of the first bubble storage unit 301 and the second bubble storage unit 302 is larger than the smallest cross-sectional area portion inside each bubble storage unit. Furthermore, each flow channel wall is provided with a slit 303 along the ink flow direction. Each slit 303 is formed thin enough not to be blocked by the bubbles 500. As a result, the relative ink flow rate in each bubble storage unit is slowed, allowing ink to be delivered out of the slit 303 without moving the bubbles 500. This prevents the bubbles 500 from flowing into the pressure chamber 113. In this embodiment, each slit has a groove shape with a width in the range of 0.2 to 0.5 mm, and the structure is such that the stored and bound bubbles 500 hardly block the slit 303.

[0114] Even with the slit 303 configured as described above, a certain amount of bubbles 500 can still be stored in the first bubble storage unit 301 and the second bubble storage unit 302. When the bubbles 500 reach the flow channel with a small cross-sectional area that increases the flow rate, they easily flow into the pressure chamber 113 due to ink pressure, leading to ejection errors. Therefore, when a certain amount of bubbles 500 is stored, it is necessary to perform a recovery operation, such as suction from the ejection port, to expel the bubbles 500 to the outside. Suction recovery devices, etc., configured to perform recovery operations by suction, are widely used structures in inkjet printers to achieve printing stability. This is not a new structure for removing the bubbles 500 stored in the first bubble storage unit 301 and the second bubble storage unit 302.

[0115] Figure 15 For along Figure 7 A cross-sectional view taken along the XV-XV line. The first bubble storage unit 301 and the second bubble storage unit 302 can move the generated bubbles to the top by ensuring the largest possible cross-sectional area. Therefore, it is desirable to form the first bubble storage unit 301 and the second bubble storage unit 302 such that the cross-sectional area of ​​the flow channel to the portion near the printed element board 110 where bubbles 500 are easily generated is increased.

[0116] In the case where, as in this embodiment, nine common supply flow channel openings 121 are alternately arranged along the direction of the nozzle array, and eight common collection flow channel openings 122 are arranged along the same direction, the openings are connected to each other using flow channels whose length (equivalent to the long side in the y-direction) is equal to or greater than the length between the two ends of each nozzle array. In this case, branches are required to supply to the openings arranged at narrow intervals. In this embodiment, as... Figure 8A and 8B As shown in the cross-sectional view, each portion to be connected to the print element board 110 is formed as a branch unit with a triangular shape, the triangle having a sloping side inclined in the x-direction, which is the scanning direction. The sloping sides of the triangular shape of the first ink connection flow channel 310 to be connected to the common supply flow channel opening 121 and the sloping sides of the triangular shape of the second ink connection flow channel 320 to be connected to the common collection flow channel opening 122 are arranged in opposite directions to each other.

[0117] As described above, a first bubble storage unit is provided, connecting the liquid supply mechanism to a supply flow channel communicating with a pressure chamber, and a second bubble storage unit is provided, connecting the liquid supply mechanism to a collection flow channel communicating with a pressure chamber. The volume of the first bubble storage unit is set to be larger than the volume of the second bubble storage unit. Therefore, a liquid injection head and a liquid injection device can be provided that suppress injection errors without increasing the size of the device.

[0118] (Second Embodiment)

[0119] The second embodiment of this disclosure will now be described with reference to the accompanying drawings. Note that the basic structure of this embodiment is the same as that of the first embodiment; therefore, the features of this embodiment will be discussed below.

[0120] Figure 16A To illustrate the circulating flow channel in inkjet mode, Figure 16B This is a schematic diagram illustrating a circulating flow channel in the case of continuous circulation for a period of time without the generation of bubbles. The liquid injection head 1000 of this embodiment includes a first bubble storage unit / first pressure regulating chamber 711 and a second bubble storage unit / second pressure regulating chamber 721. In other words, each pressure regulating chamber is also configured to function as a bubble storage unit.

[0121] The circulating flow is completed within the ink flow channel of the liquid ejector head 1000. Therefore, the bubbles 500 generated within the flow channel of the liquid ejector head 1000 should be present somewhere in the circulating flow. The bubbles 500 are generated by: foaming during ink filling, the flow of ink, etc.; supersaturation of gases dissolved in the ink associated with temperature increases or pressure decreases inside the liquid ejector head 1000; and so on. If the bubbles 500 flow into any pressure chamber 613, they tend to cause ink ejection errors, which may lead to image errors. Therefore, the bubbles 500 are temporarily stored in a first bubble storage unit / first pressure regulating chamber 711 and a second bubble storage unit / second pressure regulating chamber 721, both of which are located away from the pressure chamber 613 to prevent the bubbles 500 from flowing into the pressure chamber 613. The bubbles 500 are then expelled from the liquid ejector head 1000 by regular suction from the ejection port.

[0122] Meanwhile, the bubbles 500 stored in the second bubble storage unit and second pressure regulating chamber 721 are circulated to the first bubble storage unit and first pressure regulating chamber 711 located downstream of the circulation pump (see...). Figure 16B The volume downstream of the circulating pump is set to be larger than the volume of the flow channel upstream of the circulating pump, so that even if the bubble 500 moves to the supply flow channel side downstream of the circulating pump as described above, the bubble 500 in the first bubble storage unit and first pressure regulating chamber 711 can be prevented from reaching the pressure chamber 613. As described above, it is desirable to increase the portion capable of storing bubbles by increasing the volume. Here, a larger flow channel volume increases the capacity to store bubble 500. However, a larger flow channel volume is not always ideal, and the total flow channel volume and the volume difference between the upstream and downstream of the circulating pump need to be determined by taking into account factors such as pressure loss, initial gas quantity, and gas production quantity.

[0123] Here, the connecting flow channel between the common supply flow channel 611 and the first bubble storage unit / first pressure regulating chamber 711, and the connecting flow channel between the common collection flow channel 612 and the second bubble storage unit / second pressure regulating chamber 721, are formed to extend in the vertical direction, allowing the bubble 500 to move in the anti-gravity direction by utilizing buoyancy. Optionally, each of the above connecting flow channels preferably includes an inner wall, wherein the component of the normal vector of the top surface located above in the vertical direction has a component in the gravitational direction (z-direction).

[0124] <Reference Example>

[0125] A more detailed reference example of the liquid jetting device described above will be provided.

[0126] <Pressure Regulation Unit>

[0127] Figures 17A to 17C A diagram illustrating an example of a pressure regulating unit. (Refer to...) Figures 17A to 17C The construction and operation of the pressure regulating unit (first pressure regulating unit 1120 or second pressure regulating unit 1150) built into the liquid injection head 1000 described above will be described in more detail. Note that the first pressure regulating unit 1120 and the second pressure regulating unit 1150 have substantially the same structure. Therefore, the first pressure regulating unit 1120 will be described below as an example, and will be further described by reference to... Figures 17A to 17C The reference numerals corresponding to the first pressure regulating unit are used to illustrate the second pressure regulating unit 1150. In the case of the second pressure regulating unit 1150, the first valve chamber 1121, which will be described below, will be converted into the second valve chamber 1151, and the first pressure control chamber 1122, which will be described below, will be converted into the second pressure control chamber 1152.

[0128] The first pressure regulating unit 1120 includes a first valve chamber 1121 and a first pressure control chamber 1122 formed inside a cylindrical housing 1125. The first valve chamber 1121 and the first pressure control chamber 1122 are separated from each other by a partition wall 1123 disposed inside the cylindrical housing 1125. However, the first valve chamber 1121 communicates with the first pressure control chamber 1122 through a communication port 1191 formed in the partition wall 1123. The first valve chamber 1121 is provided with a valve 1190, which switches between communication and obstruction between the first valve chamber 1121 and the first pressure control chamber 1122 via the communication port 1191. The valve 1190 is held in a position opposite to the communication port 1191 by means of a valve spring 1200, and the valve 1190 is configured to be in close contact with the partition wall 1123 by means of a biasing force of the valve spring 1200. Due to the close contact between the valve 1190 and the partition wall 1123, ink flow through the communication port 1191 is obstructed. Here, the portion of valve 1190 that contacts the partition wall 1123 is preferably made of an elastic material to enhance tight contact with the partition wall 1123. Meanwhile, valve shaft 1190a, which is to be inserted into the communication port 1191, is positioned in a protruding manner at the center of valve 1190. By pressing valve shaft 1190a against the biasing force of valve spring 1200, valve 1190 separates from partition wall 1123, thereby allowing ink to flow through communication port 1191. In the following description, the state in which ink flow through communication port 1191 is blocked by valve 1190 will be referred to as the "closed state," while the state in which ink can flow through communication port 1191 will be referred to as the "open state."

[0129] The opening of the cylindrical shell 1125 is closed by the flexible member 1230 and the pressure plate 1210. The flexible member 1230, the pressure plate 1210, the outer wall of the shell 1125, and the partition wall 1123 form a first pressure control chamber 1122. The pressure plate 1210 can be displaced with the displacement of the flexible member 1230. Although the materials of the pressure plate 1210 and the flexible member 1230 are not limited, for example, the pressure plate 1210 can be formed from a resin molded part, and the flexible member 1230 can be formed from a resin film. In this case, the pressure plate 1210 can be fixed to the flexible member 1230 by heat sealing.

[0130] A pressure adjusting spring 1220 (biasing member) is disposed between the pressure plate 1210 and the partition wall 1123. For example... Figure 17A As shown, the pressure plate 1210 and the flexible member 1230 are biased in the direction of expanding the internal volume of the first pressure control chamber 1122 by the biasing force of the pressure regulating spring 1220. Simultaneously, when the pressure inside the first pressure control chamber 1122 decreases, the pressure plate 1210 and the flexible member 1230 overcome the pressure of the pressure regulating spring 1220 and shift in the direction of decreasing the internal volume of the first pressure control chamber 1122. Then, when the internal volume of the first pressure control chamber 1122 decreases to a predetermined amount, the pressure plate 1210 contacts the valve shaft 1190a of the valve 1190. Thereafter, as the internal volume of the first pressure control chamber 1122 further decreases, the valve 1190 overcomes the biasing force of the valve spring 1200 and moves together with the valve shaft 1190a, thereby separating from the partition wall 1123. This establishes the open state of the communication port 1191. Figure 17B (The state in the middle).

[0131] In this embodiment, with the connection port 1191 in the open state, the connection arrangement in the circulation path causes the pressure in the first valve chamber 1121 to be higher than the pressure in the first pressure control chamber 1122. Therefore, with the connection port 1191 in the open state, ink flows from the first valve chamber 1121 into the first pressure control chamber 1122. This inflow of ink causes the flexible member 1230 and the pressure plate 1210 to shift in a direction that increases the internal volume of the first pressure control chamber 1122. As a result, the pressure plate 1210 separates from the valve shaft 1190a of the valve 1190, and the valve 1190 comes into close contact with the partition wall 1123 by the bias force of the valve spring 1200. Therefore, the closed state of the connection port 1191 is established. Figure 17C (The state in the middle).

[0132] As described above, according to the first pressure regulating unit 1120 of this embodiment, when the pressure in the first pressure control chamber 1122 drops below a predetermined pressure (for example, in the case of increased negative pressure), ink flows in from the first valve chamber 1121 through the communication port 1191. Therefore, further pressure reduction in the first pressure control chamber 1122 is prevented. In this way, the first pressure control chamber 1122 is controlled so that the pressure therein is maintained within a predetermined range.

[0133] The pressure in the first pressure control chamber 1122 will be described in further detail below.

[0134] Let us consider the state in which the flexible member 1230 and the pressure plate 1210 are displaced according to the pressure in the first pressure control chamber 1122 as described above. Figure 17B (in the state of the valve), and establishes the closed state of the communication port 1191 by contacting the pressure plate 1210 with the valve shaft 1190a. In this case, the relationship of the forces acting on the pressure plate 1210 is expressed by the following formula 1:

[0135] P2×S2+F2+(P1–P2)×S1+F1=0 Formula 1

[0136] Furthermore, Equation 1 gives the following formula for the rearrangement of P2:

[0137] P2=-(F1+F2+P1×S1) / (S2–S1) Formula 2

[0138] in

[0139] P1: Pressure (gauge pressure) in the first valve chamber 1121

[0140] P2: Pressure (gauge pressure) in the first pressure control chamber 1122

[0141] F1: The spring force of the valve spring 1200.

[0142] F2: Spring force of pressure adjusting spring 1220

[0143] S1: Pressure receiving area of ​​valve 1190, and

[0144] S2: Pressure receiving area of ​​pressure plate 1210.

[0145] Here, the spring force F1 of valve spring 1200 and the spring force F2 of pressure regulating spring 1220 are determined to be positive according to the direction of pressure valve 1190 and pressure plate 1210. Figure 17B (in the left direction). At the same time, regarding the pressure P1 in the first valve chamber 1121 and the pressure P2 in the first pressure control chamber 1122, the pressure P1 is configured to satisfy the relationship P1≥P2.

[0146] With the connection port 1191 open, the pressure P2 in the first pressure control chamber 1122 is determined by Formula 2. With the connection port 1191 open, ink flows from the first valve chamber 1121 into the first pressure control chamber 1122 by satisfying the relationship P1 ≥ P2. As a result, the pressure P2 in the first pressure control chamber 1122 does not decrease further, and the pressure P2 remains within a predetermined range.

[0147] On the other hand, such as Figure 17C As shown, when the communication port 1191 is closed due to the non-contact state between the pressure plate 1210 and the valve shaft 1190a, the relationship of the forces acting on the pressure plate 1210 is expressed by the following formula 3:

[0148] P3×S3+F3=0 Formula 3

[0149] Here, Equation 3 gives the following expression for the rearrangement of P3:

[0150] P3=-F3 / S3 Formula 4

[0151] in

[0152] F3: The spring force of the pressure regulating spring 1220 when the pressure plate 1210 and the valve shaft 1190a are not in contact;

[0153] P3: The pressure (gauge pressure) in the first pressure control chamber 1122 when there is no contact between the pressure plate 1210 and the valve shaft 1190a; and

[0154] S3: Pressure receiving area of ​​pressure plate 1210 when there is no contact between pressure plate 1210 and valve shaft 1190a.

[0155] Here, Figure 17C This indicates that the pressure plate 1210 and the flexible component 1230 are in Figure 17C The pressure P3 in the first pressure control chamber 1122, the spring force F3 of the pressure regulating spring 1220, and the pressure receiving area S3 of the pressure plate 1210 are adjusted according to the pressure plate 1210 and the flexible member 1230 as they shift to the rightward direction to their maximum displacement limit. Figure 17C The state changes due to the shift during the process. More precisely, it changes with... Figure 17C Compared to the state shown, when the pressure plate 1210 and the flexible member 1230 are located Figure 17C When the pressure is directed to the left, the pressure receiving area S3 of the pressure plate 1210 decreases, and the spring force F3 of the pressure regulating spring 1220 increases. As a result, the pressure P3 in the first pressure control chamber 1122 decreases due to Equation 4. Therefore, due to Equations 2 and 4, when the pressure is directed to the left... Figure 17BThe state transition in Figure 17C During the period of the state described above, the pressure in the first pressure control chamber 1122 gradually increases (i.e., the negative pressure decreases to a value close to the positive pressure side). In other words, during the period when the pressure plate 1210 and the flexible member 1230 are gradually displaced to the right from the open state of the communication port 1191 and the internal volume of the first pressure control chamber 1122 eventually reaches its displacement limit, the pressure in the first pressure control chamber 1122 gradually increases. In short, the negative pressure gradually decreases.

[0156] <Circulation Pump>

[0157] Next, we will refer to Figure 18A , 18B The construction and operation of the circulation pump 1500 built into the liquid injection head 1000 described above are described in more detail in sections 1 and 19.

[0158] Figure 18A and 18B This is an external perspective view of the 1500 circulating pump. Figure 18A This is an external perspective view showing the front of the circulating pump 1500. Figure 18B This is an external perspective view showing the rear side of the circulating pump 1500. The outer casing of the circulating pump 1500 is formed by a pump housing 1505 and a cover 1507 fixed to the pump housing 1505. The pump housing 1505 is formed by a housing body 1505a and a flow channel connecting member 1505b attached to and fixed to the outer surface of the housing body 1505a. The housing body 1505a and the flow channel connecting member 1505b each have a pair of through holes at two different locations. The through holes formed at each location are interconnected. The pair of through holes at one location together form a pump supply port 1501, while the pair of through holes at the other location together form a pump discharge port 1502. The pump supply port 1501 is connected to a pump inlet flow channel 1170, which is connected to a second pressure control chamber 1152. The pump discharge port 1502 is connected to a pump outlet flow channel 1180, which is connected to a first pressure control chamber 1122. Ink supplied from pump supply port 1501 passes through pump chamber 1503, which will be described later (see [link]). Figure 19 ), and discharged from pump discharge port 1502.

[0159] Figure 19 yes Figure 18AThe diagram shows a cross-sectional view of the circulating pump 1500 taken along line XIX-XIX. A diaphragm 1506 is attached to the inner surface of the pump housing 1505, and a pump chamber 1503 is formed between the diaphragm 1506 and a recess formed in the inner surface of the pump housing 1505. The pump chamber 1503 communicates with a pump supply port 1501 and a pump discharge port 1502 formed in the pump housing 1505. Meanwhile, a check valve 1504a is disposed in the middle portion of the pump supply port 1501, and a check valve 1504b is disposed in the middle portion of the pump discharge port 1502. More precisely, the check valve 1504a is configured such that a portion of the check valve 1504a can be used in the space 1512a defined in the middle portion of the pump supply port 1501. Figure 19 The valve moves to the left. Simultaneously, the check valve 1504b is configured such that a portion of the check valve 1504b can be within the space 1512b defined at the middle portion of the pump discharge port 1502. Figure 19 Move to the right from the center.

[0160] When the volume of pump chamber 1503 increases due to the displacement of diaphragm 1506, resulting in a decrease in pressure within pump chamber 1503, check valve 1504a disengages from the opening of pump supply port 1501 in space 1512a (i.e., in Figure 19 (Moving to the left). Check valve 1504a disengages from the opening of pump supply port 1501 in space 1512a, establishing an open state that allows ink to flow through pump supply port 1501. On the other hand, when the volume of pump chamber 1503 decreases due to the displacement of diaphragm 1506, causing an increase in pressure in pump chamber 1503, check valve 1504a comes into close contact with the wall surface surrounding the opening of pump supply port 1501. As a result, a closed state is established to block ink from flowing through pump supply port 1501.

[0161] Simultaneously, when the pressure in the pump chamber 1503 decreases, the check valve 1504b comes into close contact with the wall surrounding the opening of the pump housing 1505, forming a closed state to prevent ink from flowing through the pump discharge port 1502. On the other hand, when the pressure in the pump chamber 1503 increases, the check valve 1504b disengages from the opening of the pump housing 1505 (i.e., in...). Figure 19 (Move to the right from the center) and move toward space 1512b, so that ink can flow through pump discharge hole 1502.

[0162] Here, the materials of each check valve 1504a and 1504b only need to have deformable characteristics according to the pressure inside the pump chamber 1503. The check valves can be formed from elastic components such as EPDM and elastomers, or from films or sheets such as polypropylene. However, the applicable materials are not limited to these materials.

[0163] As described above, the pump chamber 1503 is formed by attaching the pump housing 1505 to the diaphragm 1506. Therefore, the pressure in the pump chamber 1503 changes with the deformation of the diaphragm 1506. For example, the volume of the pump chamber 1503 changes due to the displacement of the diaphragm 1506 toward the pump housing 1505. Figure 19 When the pressure in pump chamber 1503 decreases due to the rightward shift of the pump outlet 1502, the pressure increases. Therefore, the check valve 1504b, positioned opposite the pump discharge port 1502, is set to open, and ink is discharged from pump chamber 1503. In this case, the check valve 1504a, positioned opposite the pump supply port 1501, is in close contact with the wall surface surrounding the pump supply port 1501. Therefore, backflow of ink from pump chamber 1503 to pump supply port 1501 is suppressed.

[0164] On the other hand, when the diaphragm 1506 moves in the direction that expands the pump chamber 1503, the pressure in the pump chamber 1503 decreases. Therefore, the check valve 1504a, which is positioned opposite the pump supply port 1501, is set to the open state, and ink is supplied to the pump chamber 1503. In this case, the check valve 1504b, located at the pump discharge port 1502, comes into close contact with the wall surface surrounding the opening formed in the pump housing 1505 and blocks the opening. Therefore, backflow of ink from the pump discharge port 1502 to the pump chamber 1503 is suppressed.

[0165] As described above, in the circulating pump 1500, ink is drawn in and discharged by changing the pressure in the pump chamber 1503 as the diaphragm 1506 shifts. In this case, when bubbles enter the pump chamber 1503, the pressure change in the pump chamber 1503 is reduced due to the expansion and contraction of the bubbles, regardless of the displacement of the diaphragm 1506, thereby reducing the liquid supply. Therefore, the pump chamber 1503 is arranged parallel to gravity so that bubbles entering the pump chamber 1503 easily accumulate in the upper part of the pump chamber 1503, and the pump discharge port 1502 is located in the portion above the center of the pump chamber 1503. In this way, the performance of discharging bubbles from the pump can be improved and the flow rate can be stabilized.

[0166] Ink Flow in a Liquid Jet Head

[0167] Figures 20A to 20E This is a diagram used to explain the ink flow in a liquid ejector head. (Refer to...) Figures 20A to 20E This describes the ink circulation process performed in the liquid ejector head 1000. To explain the ink circulation path more clearly, in... Figures 20A to 20E The relative positions of the various structures (first pressure regulating unit 1120, second pressure regulating unit 1150, circulating pump 1500, etc.) have been simplified. Therefore, the relative positions of these structures differ from those described later. Figure 28 The relative positions of the structures within. Figure 20AThis schematically illustrates the ink flow during a printing operation, where printing is performed simultaneously with ink ejection from nozzle 1013. Note that... Figure 20A The arrows in the diagram indicate ink flow. In this embodiment, both the external pump 1021 and the circulation pump 1500 are started when a printing operation is performed. Here, the external pump 1021 and the circulation pump 1500 can be driven independently of the printing operation. Alternatively, the external pump 1021 and the circulation pump 1500 do not need to be driven in series, but can be driven independently of each other.

[0168] During the printing operation, the circulation pump 1500 is in the on (driven) state, and ink flowing from the first pressure control chamber 1122 flows into the supply flow channel 1130 and the bypass flow channel 1160. The ink flowing into the supply flow channel 1130 passes through the ejection module 1300 and then flows into the collection flow channel 1140. Thereafter, ink is supplied to the second pressure control chamber 1152.

[0169] Simultaneously, ink flowing from the first pressure control chamber 1122 into the bypass flow channel 1160 passes through the second valve chamber 1151 and flows into the second pressure control chamber 1152. The ink flowing into the second pressure control chamber 1152 passes through the pump inlet flow channel 1170, the circulation pump 1500, and the pump outlet flow channel 1180, and then flows back into the first pressure control chamber 1122. In this case, based on the relationship in Formula 2 above, the control pressure of the first valve chamber 1121 is set higher than the control pressure of the first pressure control chamber 1122. Therefore, the ink in the first pressure control chamber 1122 is again supplied to the injection module 1300 through the supply flow channel 1130, without flowing into the first valve chamber 1121. The ink flowing into the injection module 1300 passes through the collection flow channel 1140, the second pressure control chamber 1152, the pump inlet flow channel 1170, the circulation pump 1500, and the pump outlet flow channel 1180, and then flows back into the first pressure control chamber 1122. Therefore, ink circulation is performed as described above, which is done inside the liquid jet head 1000.

[0170] In the ink circulation described above, the circulation volume (flow rate) of ink in the ejection module 1300 is determined by the pressure difference between the control pressures of the first pressure control chamber 1122 and the second pressure control chamber 1152. This pressure difference is then set to achieve a circulation volume capable of suppressing the increase in ink viscosity near each ejection port in the ejection module 1300. Furthermore, an amount of ink equivalent to the amount consumed during printing is supplied from the ink tank 2 to the first pressure control chamber 1122 through the filter 1110 and the first valve chamber 1121. The mechanism of supplying ink at the consumption rate will be described in detail below. The pressure inside the first pressure control chamber decreases as the ink in the circulation path decreases, by an amount equal to the amount of ink consumed during printing. As a result, the ink in the first pressure control chamber 1122 also decreases. As the ink in the first pressure control chamber 1122 decreases, the internal volume of the first pressure control chamber 1122 decreases. Due to this decrease in the internal volume of the first pressure control chamber 1122, the connection port 1191A is set to the open state, and ink is supplied from the first valve chamber 1121 to the first pressure control chamber 1122. During the flow of ink from the first valve chamber 1121 through the connecting port 1191A, a pressure loss occurs in the supplied ink, and the ink, which was under positive pressure, becomes under negative pressure due to its flow into the first pressure control chamber 1122. Then, the ink flows from the first valve chamber 1121 into the first pressure control chamber 1122, causing an increase in pressure inside the first pressure control chamber, thereby increasing the internal volume of the first pressure control chamber and establishing the closed state of the connecting port 1191A. In this way, the opening and closing states are repeated in the connecting port 1191A as ink is consumed. Meanwhile, when no ink is consumed, the connecting port 1191A remains in the closed state.

[0171] Figure 20B The diagram schematically illustrates the immediate ink flow after the printing operation is completed and the circulation pump 1500 is switched to the off state (stopped state). Upon completion of the printing operation and with the circulation pump 1500 off, the pressures in the first pressure control chamber 1122 and the second pressure control chamber 1152 are both set as control pressures during the printing operation. Therefore, based on the pressure difference between the pressures in the first pressure control chamber 1122 and the second pressure control chamber 1152, such as... Figure 20B The movement of ink is shown. More precisely, ink flow is continuously generated from the first pressure control chamber 1122 through the supply flow channel 1130 to the jet module 1300 and then through the collection flow channel 1140 to the second pressure control chamber 1152. Simultaneously, ink flow is also continuously generated from the first pressure control chamber 1122 through the bypass flow channel 1160 and the second valve chamber 1151 to the second pressure control chamber 1152.

[0172] Due to these ink flows, an amount of ink equivalent to the amount that has moved from the first pressure control chamber 1122 to the second pressure control chamber 1152 is supplied from the ink tank 2 through the filter 1110 and the first valve chamber 1121 to the first pressure control chamber 1122. As a result, the contents of the first pressure control chamber 1122 remain constant. Based on the relationship in Formula 2 above, when the contents of the first pressure control chamber 1122 are constant, the spring force F1 of the valve spring 1200, the spring force F2 of the pressure regulating spring 1220, the pressure receiving area S1 of the valve 1190, and the pressure receiving area S2 of the pressure plate 1210 remain constant. Therefore, the pressure in the first pressure control chamber 1122 is determined according to the change in the pressure (gauge pressure) P1 in the first valve chamber 1121. Therefore, when the pressure P1 in the first valve chamber 1121 does not change, the pressure P2 in the first pressure control chamber 1122 remains at the same pressure as the control pressure during the printing operation.

[0173] On the other hand, the pressure in the second pressure control chamber 1152 changes over time according to the changes in the contents related to the ink inflow from the first pressure control chamber 1122. More precisely, from... Figure 20B The state in the middle changes to such Figure 20C During the period shown (a state of non-communication between the second valve chamber 1151 and the second pressure control chamber 1152 due to the closure of the connection port 1191), the pressure in the second pressure control chamber 1152 changes according to Formula 2. Thereafter, the pressure plate 1210 and valve shaft 1190a transition to a non-contact state, thereby establishing the closure of the connection port 1191. Then, as... Figure 20D As shown, ink flows from the collection flow channel 1140 into the second pressure control chamber 1152. Due to this ink inflow, the pressure plate 1210 and the flexible member 1230 are displaced. Therefore, the pressure in the second pressure control chamber 1152 varies according to Formula 4, or more specifically, increases until the contents of the second pressure control chamber 1152 reach their maximum value.

[0174] Note that in the event Figure 20CIn the indicated state, no ink flow occurs from the first pressure control chamber 1122 to the second pressure control chamber 1152 via the bypass flow channel 1160 and the second valve chamber 1151. Therefore, ink flow occurs only in the first pressure control chamber 1122, and this ink flow is supplied to the jet module 1300 via the supply flow channel 1130, and then reaches the second pressure control chamber 1152 via the collection flow channel 1140. As described above, the movement of ink from the first pressure control chamber 1122 to the second pressure control chamber 1152 is generated based on the pressure difference between the pressure in the first pressure control chamber 1122 and the pressure in the second pressure control chamber 1152. Therefore, the ink movement stops when the pressure in the second pressure control chamber 1152 becomes equal to the pressure in the first pressure control chamber 1122.

[0175] Simultaneously, with the pressure in the second pressure control chamber 1152 equal to the pressure in the first pressure control chamber 1122, the second pressure control chamber 1152 expands to... Figure 20D The state shown. In the second pressure control chamber 1152, as indicated. Figure 20D In the case of expansion shown, a storage unit capable of storing ink is formed in the second pressure control chamber 1152. Although it can vary depending on the shape and size of the flow channel and the properties of the ink, the stop state of the circulation pump 1500 transitions to the starting state within a period of approximately 1 to 2 minutes. Figure 20D The state shown. (As indicated) Figure 20D When the circulation pump 1500 is driven while the ink is stored in the storage unit, the ink in the storage unit is supplied to the first pressure control chamber 1122 by using the circulation pump 1500. Therefore, as shown... Figure 20E As shown, the ink volume in the first pressure control chamber 1122 increases, and the flexible member 1230 and the pressure plate 1210 shift in the expansion direction. Then, as the circulation pump 1500 is continuously driven, the state inside the circulation path will be changed, such as... Figure 20A As shown.

[0176] In the above description, Figure 20A This has already been explained as an example of a printing operation. However, as mentioned before, the ink can circulate regardless of how the printing operation is performed. Similarly, in this case, depending on the driving and stopping of the circulation pump 1500, the ink will produce... Figures 20A to 20E The ink flow shown.

[0177] As described above, this embodiment employs an example in which the connection port 1191B in the second pressure regulating unit 1150 is set to an open state when ink is circulated by the driving circulation pump 1500, and is set to a closed state when ink circulation stops. However, this disclosure is not limited to this configuration. The control pressure in the connection port 1191B in the second pressure regulating unit 1150 can be set to maintain a closed state even when ink is circulated by the driving circulation pump 1500. This configuration and the function of the bypass flow channel 1160 will be described in detail below.

[0178] A bypass flow channel 1160 is provided to connect the first pressure regulating unit 1120 to the second pressure regulating unit 1150 so as not to adversely affect the jet module 1300, for example, if the negative pressure generated in the circulation path exceeds a predetermined value. Furthermore, the bypass flow channel 1160 is provided to supply ink from the supply flow channel 1130 side and the collection flow channel 1140 side into the pressure chamber 1012.

[0179] An example of providing a bypass flow channel 1160 to prevent adverse effects on the ejection module 1300 when the negative pressure exceeds a predetermined value will now be described. For example, changes in ambient temperature may alter the properties of the ink (e.g., viscosity). When the ink viscosity changes, the pressure loss in the circulation path also changes. For example, when the ink viscosity decreases, the pressure loss in the circulation path decreases. As a result, the flow rate of the circulation pump 1500, driven at a constant drive, increases, and therefore the flow rate in the ejection module 1300 increases. On the other hand, the ejection module 1300 is maintained at a constant temperature by using a temperature regulating mechanism (not shown). Therefore, even when the ambient temperature changes, the viscosity of the ink in the ejection module 1300 remains constant. Since the flow rate of the ink flowing in the ejection module 1300 increases while the viscosity of the ink in the ejection module 1300 remains unchanged, the negative pressure in the ejection module 1300 increases due to flow resistance. If the negative pressure in the ejection module 1300 exceeds the predetermined value as described above, the meniscus on the ejection nozzle 1013 may be disrupted, thus normal ejection may become infeasible. Even if the meniscus is not damaged, the negative pressure in pressure chamber 1012 exceeds the specified value, and the jets from it may be adversely affected.

[0180] In view of this situation, in this embodiment, a bypass flow channel 1160 is formed within the circulation path. By providing the bypass flow channel 1160, ink also flows in the bypass flow channel 1160 when the negative pressure exceeds a predetermined value. Therefore, the pressure in the injection module 1300 can be kept constant. Therefore, the connection port 1191B in the second pressure regulating unit 1150 can be provided with a control pressure that keeps it closed even when the circulation pump 1500 is driven. Furthermore, the control pressure in the second pressure regulating unit 1150 can be set such that the connection port 1191B in the second pressure regulating unit 1150 opens when the negative pressure exceeds a predetermined value. In other words, as long as the flow rate change in the pump caused by viscosity changes such as environmental changes does not disrupt the meniscus, or as long as the predetermined negative pressure is maintained, the connection port 1191B can be in a closed state when the circulation pump 1500 is driven.

[0181] <Construction of the jet unit>

[0182] Figure 21A and 21B This is a schematic diagram illustrating the circulation path for one ink color in the spraying unit 1003 of this embodiment. Figure 21A This is an exploded perspective view of the injection unit 1003 as seen from the side of the first support member 1004. Figure 21B This is an exploded perspective view of the injection unit 1003, viewed from the injection module 1300 side. Note that... Figure 21A and 21B Each arrow marked with inlet and outlet indicates the flow of ink. Although the flow of ink for one color will be discussed here, other colors of ink exhibit similar flow patterns. Meanwhile, in Figure 21A and 21B The illustrations of the second support member and the wiring member are omitted. Explanations of these components are also omitted in the following description of the construction of the injection unit. The injection module 1300 includes an injection element plate 1340 and an opening plate 1330. Figure 22 This is a diagram showing the opening plate 1330. Figure 23 This is a diagram showing the injection element plate 1340.

[0183] Ink is supplied from circulation unit 200 to injection unit 1003 via a coupling member (not shown). The ink path from the point where the ink passes through the coupling member to the point where the ink returns to the coupling member will be described.

[0184] The ejection module 1300 includes an ejection element plate 1340 and an opening plate 1330, which serve as a silicon substrate 1310. The ejection module 1300 also includes an ejection nozzle forming member 1320. The ejection element plate 1340, the opening plate 1330, and the ejection nozzle forming member 1320 are stacked and combined with each other in a manner that establishes communication for flow channels for various inks, thereby constituting the ejection module 1300 supported by a first support member 1004. The ejection unit 1003 is formed by supporting the ejection module 1300 by the first support member 1004. The ejection element plate 1340 includes the ejection nozzle forming member 1320. The ejection nozzle forming member 1320 includes rows of ejection nozzles, each row formed by an array of ejection nozzles 1013. A portion of the ink supplied through the ink flow channels in the ejection module 1300 is ejected from each ejection nozzle 1013. Unejected ink is recovered through the ink flow channels in the ejection module 1300.

[0185] like Figure 21A , 21B As shown in Figure 22, the opening plate 1330 includes an array of ink supply ports 1311 and an array of ink collection ports 1312. For example... Figure 23 and 24A As shown in 24C, the jetting element plate 1340 includes an array of supply connection flow channels 1323 and an array of collection connection flow channels 1324. Additionally, the jetting element plate 1340 includes a common supply flow channel 1018 communicating with the supply connection flow channels 1323 and a common collection flow channel 1019 communicating with the collection connection flow channels 1324. The ink flow channels in the jetting unit 1003 are formed by communicating the ink supply flow channel 1048 and the ink collection flow channel 1049 provided on the first support member 1004 with the flow channels provided on the jetting module 1300. The support member supply port 1211 is a cross-sectional opening constituting the ink supply flow channel 1048, and the support member collection port 1212 is a cross-sectional opening constituting the ink collection flow channel 1049.

[0186] Ink to be supplied to the jetting unit 1003 is supplied from the circulation unit 200 side to the ink supply flow channel 1048 of the first support member 1004. Ink flowing through the support member supply port 1211 in the ink supply flow channel 1048 is supplied through the ink supply flow channel 1048 and the ink supply port 1311 of the opening plate 1330 to the common supply flow channel 1018 of the jetting element plate 1340, and then enters the supply connection flow channel 1323. These flow channels together constitute the supply-side flow channel. Thereafter, ink flows through the pressure chamber 1012 of the jetting nozzle forming member 1320 to the collection connection flow channel 1324 of the collection-side flow channel. Details of the ink flow in each pressure chamber 1012 will be described later.

[0187] In the collection-side flow channel, the ink entering the collection connection flow channel 1324 flows into the common collection flow channel 1019. Thereafter, the ink flows from the common collection flow channel 1019 through the ink collection port 1312 of the opening plate 1330 to the ink collection flow channel 1049 of the first support member 1004, and is recovered by the circulation unit 200.

[0188] The area in the opening plate 1330 where neither the ink supply port 1311 nor the ink collection port 1312 is provided corresponds to the area in the first support member 1004 used to separate the support member ink supply port 1211 and the support member ink collection port 1212. Furthermore, no opening is provided to the first support member 1004 in this area. When the jetting module 1300 is attached to the first support member 1004, the aforementioned area serves as the attachment area.

[0189] exist Figure 22 In the opening plate 1330, multiple rows of openings arranged in the x direction are provided in the y direction. Here, the supply (inlet) and collection (outlet) are alternately arranged in the y direction, offset by half a pitch in the x direction. Figure 23 In the injection element plate 1340, a common supply flow channel 1018 communicating with a supply connection flow channel 1323 arranged in the y-direction and a common collection flow channel 1019 communicating with a collection connection flow channel 1324 arranged in the y-direction are arranged alternately in the x-direction. The common supply flow channel 1018 and the common collection flow channel 1019 are separated by the type of ink. Furthermore, the number of common supply flow channels 1018 and common collection flow channels 1019 is determined according to the number of nozzle rows for the corresponding color. Simultaneously, the supply connection flow channels 1323 and collection connection flow channels 1324 are also arranged in a number corresponding to the number of nozzles 1013. Here, the supply connection flow channels 1323 and collection connection flow channels 1324 do not necessarily correspond one-to-one with the nozzles 1013. One supply connection flow channel 1323 and one collection connection flow channel 1324 can handle two or more nozzles 1013.

[0190] The aforementioned opening plate 1330 and jet element plate 1340 are stacked and combined to establish communication between the flow channels for various inks, thereby forming a jet module 1300 supported by the first support member 1004. Thus, as described above, an ink flow channel including a supply flow channel and a collection flow channel is formed.

[0191] Figures 24A to 24C A cross-sectional view showing the ink flow at different parts of the jetting unit 1003. Figure 24A It shows along Figure 21AThe cross-sectional view taken along line XXIVA-XXIVA shows the section connecting the ink supply flow channel 1048 and the ink supply port 1311 in the jetting unit 1003. Meanwhile, Figure 24B It shows along Figure 21A The cross-sectional view taken along line XIVB-XXIVB shows the section connecting the ink collection flow channel 1049 and the ink collection port 1312 in the jetting unit 1003. Meanwhile, Figure 24C It shows along Figure 21A The cross-sectional view taken along line XIVC-XXIVC shows the section of the part of the ink supply port 1311 or ink collection port 1312 that is not connected to the flow channel of the first support member 1004.

[0192] In the supply flow channel of ink, such as Figure 24A As shown, ink is supplied from the portion of the ink supply flow channel 1048 of the first support member 1004 that overlaps and connects with the ink supply port 1311 of the opening plate 1330. Simultaneously, in the ink collection flow channel for recovering ink, ink is recovered from the portion of the ink collection flow channel 1049 of the first support member 1004 that overlaps and connects with the ink collection port 1312 of the opening plate 1330, as shown. Figure 24B As shown. Simultaneously, there are also areas in the jetting unit 1003 where no opening is provided to the opening plate 1330. In such areas, ink is not supplied or recovered between the jetting element plate 1340 and the first support member 1004. As... Figure 24A As shown, ink is supplied in the area where the ink supply port 1311 is located, and as... Figure 24B As shown, ink is recovered in the area where the ink collection port 1312 is provided. Although an example of a construction using the opening plate 1330 has been described in this embodiment, a mode without the opening plate 1330 is also acceptable. For example, a construction in which the first support member 1004 is provided with flow channels corresponding to the ink supply flow channel 1048 and the ink collection flow channel 1049, and the jet element plate 1340 is integrated into the first support member 1004, is also acceptable.

[0193] Figure 25A and 25B This is a cross-sectional view showing a portion near an injection port 1013 in the injection module 1300. Note that... Figure 25A and 25BThe thick arrows shown in the common supply flow channel 1018 and common collection flow channel 1019 indicate the oscillation of ink when using the tandem liquid jetting device 2000. Ink supplied to the pressure chamber 1012 via the common supply flow channel 1018 and the supply connection flow channel 1323 is ejected from the jet nozzle 1013 by driving the jetting element 1015. When the jetting element 1015 is not driven, the ink passes through the pressure chamber 1012 and the collection connection flow channel 1324, which serves as the collection flow channel, and is recovered by the common collection flow channel 1019.

[0194] When using the aforementioned series-type liquid jetting device 2000 to jet circulating ink, the oscillation of ink in the ink flow channel has a significant impact on ink jetting, which is attributed to the main scan of the liquid jetting head 1000. More precisely, the effect of ink oscillation in the ink flow channel manifests as a difference in ink jetting volume or a deviation in jetting direction.

[0195] In view of the above, the public supply flow channel 1018 and the public collection flow channel 1019 of this embodiment are constructed as follows: Figure 25A and 25B The cross-section shown extends along the y-direction and also along the z-direction, which is perpendicular to the x-direction, which is the main scanning direction. This configuration can reduce the width of each of the common supply flow channel 1018 and the common collection flow channel 1019 in the main scanning direction. The ink oscillation caused by the inertial force applied in the direction opposite to the scanning direction ( Figure 25A and 25B The thick black arrow (in the image) acts on the ink in the common supply flow channel 1018 and the common collection flow channel 1019 during the main scan. This ink oscillation is reduced by decreasing the width of each of the common supply flow channel 1018 and the common collection flow channel 1019 in the main scan direction. This suppresses the adverse effects of ink oscillation on ink ejection. Furthermore, each of the common supply flow channel 1018 and the common collection flow channel 1019 extends in the z-direction to increase the cross-sectional area, thereby reducing the pressure drop in the flow channels.

[0196] As described above, the common supply flow channel 1018 and the common collection flow channel 1019 are configured to reduce ink oscillation by setting a small width for the common supply flow channel 1018 and the common collection flow channel 1019 in the main scanning direction. However, this configuration cannot completely eliminate oscillation. Therefore, this embodiment is configured to deploy the common supply flow channel 1018 and the common collection flow channel 1019 at positions where they overlap each other in the x-direction in order to suppress the occurrence of jetting differences between different types of ink (jetting differences may still occur even if the amount of oscillation is reduced).

[0197] As described above, in this embodiment, the supply connection flow channel 1323 and the collection connection flow channel 1324 are arranged corresponding to the ejection port 1013. Furthermore, the supply connection flow channel 1323 and the collection connection flow channel 1324 have a juxtaposed correspondence in the x-direction, with the ejection port 1013 inserted between them. Therefore, there is a portion of the common supply flow channel 1018 that does not overlap with the common collection flow channel 1019 in the x-direction. If the correspondence between the supply connection flow channel 1323 and the collection connection flow channel 1324 in the x-direction is disrupted, the flow and ejection of ink in the pressure chamber 1012 in the x-direction may be adversely affected. Here, the increased adverse effect of ink oscillation may have a greater impact on the ink ejected from each ejection port.

[0198] For this purpose, the common supply flow channel 1018 is positioned to overlap with the common collection flow channel 1019 along the x-direction. In this way, during the main scan, the oscillation of ink in the common supply flow channel 1018 is substantially equal to the oscillation of ink in the corresponding common collection flow channel 1019 at any position in the y-direction where the ejector nozzle 1013 is arranged. As a result, stable ejection can be achieved while avoiding significant changes in the pressure difference between the common supply flow channel 1018 side and the common collection flow channel 1019 side, which could occur in each pressure chamber 1012.

[0199] Meanwhile, some circulating ink liquid ejector heads can be configured to use the same flow channels to form a flow channel for supplying ink to the liquid ejector head and a flow channel for recovering ink therefrom. On the other hand, according to this embodiment, the common supply flow channel 1018 and the common collection flow channel 1019 are configured as separate flow channels. Furthermore, each pressure chamber 1012 is in communication with the supply connection flow channel 1323, and the pressure chamber 1012 is also in communication with the collection connection flow channel 1324. Therefore, ink is ejected from the ejection port 1013 of the pressure chamber 1012. In other words, the pressure chamber 1012, which serves as the path connecting the supply connection flow channel 1323 to the collection connection flow channel 1324, is also provided with an ejection port 1013. Therefore, an ink flow from the supply connection flow channel 1323 side to the collection connection flow channel 1324 side is generated in the pressure chamber 1012, and the ink in the pressure chamber 1012 is effectively circulated. Effective circulation of ink in pressure chamber 1012 can keep the ink in pressure chamber 1012 fresh, even though the ink is prone to evaporation from nozzle 1013.

[0200] Simultaneously, the two flow channels, the common supply flow channel 1018 and the common collection flow channel 1019, are connected to the corresponding pressure chamber 1012. Therefore, ink can be supplied from both flow channels even when high flow rates are required for jetting. In other words, compared to a configuration that supplies and collects ink using only one flow channel, the configuration of this embodiment has the advantage of not only efficiently performing the cycle but also handling high-flow-rate jetting.

[0201] Meanwhile, when the common supply flow channel 1018 and the common collection flow channel 1019 are located close to each other in the x-direction, the adverse effects of ink oscillation become smaller. This spacing between the flow channels can ideally be set in the range of 75 to 100 μm.

[0202] Figure 26 A diagram showing the spray element plate 1340 for comparison. Note that... Figure 26 The supply connection flow channel 1323 and the collection connection flow channel 1324 are not shown in the diagram. Ink receiving heat energy from the jetting element 1015 in the pressure chamber 1012 flows into the common collection flow channel 1019. Therefore, the ink flowing therein has a relatively higher temperature than the ink in the common supply flow channel 1018. In this case, in the comparative example, there is a portion in the x-direction of the jetting element plate 1340, for example, made of... Figure 26 The portion α enclosed by the dashed line is the part where only the common collection flow channel 1019 exists. In this case, the temperature of the relevant portion locally increases. Therefore, temperature variations may occur in the injection module 1300, which may adversely affect the injection.

[0203] The ink flowing in the common supply flow channel 1018 has a relatively lower temperature compared to the temperature in the common collection flow channel 1019. Therefore, when the common supply flow channel 1018 and the common collection flow channel 1019 are adjacent to each other, a certain degree of temperature difference is offset between them, thus suppressing temperature rise. Therefore, the common supply flow channel 1018 and the common collection flow channel 1019, having substantially the same length, are preferably located at a position where they overlap and are adjacent to each other in the x-direction.

[0204] Figure 27A and 27B This diagram illustrates the flow channel structure of a liquid injection head 1000 suitable for three colors of ink: cyan (C), magenta (M), and yellow (Y). (See diagram below.) Figure 27A As shown, the liquid jet head 1000 is provided with a circulating flow channel for the corresponding ink type. The pressure chamber 1012 is located in the x-direction, which is the main scanning direction of the liquid jet head 1000. Meanwhile, as... Figure 27B As shown, the public supply flow channel 1018 and the public collection flow channel 1019 are arranged along the row of nozzles where the nozzles 1013 are arranged, and the public supply flow channel 1018 and the public collection flow channel 1019 are arranged to extend in the y direction such that the row of nozzles is inserted therebetween.

[0205] <Connection between the main unit and the liquid injection head>

[0206] Figure 28 This is a schematic structural diagram illustrating the details of the connection between the ink tank 2 and the external pump 1021, which are mounted on the main unit of the liquid jetting device 2000, and the liquid jetting head 1000, as well as the layout of the circulation pump, etc. The liquid jetting device 2000 according to this embodiment has a configuration that facilitates replacement of the liquid jetting head 1000 only in the event of a failure. More specifically, a liquid connection unit 1700 is provided, which facilitates the connection and disconnection of the liquid jetting head 1000 from the ink supply tube 1059 connected to the external pump 1021. This allows for easy attachment and removal of the liquid jetting head 1000 from the liquid jetting device 2000.

[0207] like Figure 28 As shown, the liquid connection unit 1700 includes a liquid connector insertion slot 1053a protruding from the head housing 1053 of the liquid ejector head 1000, and a cylindrical liquid connector 1059a insertable into the liquid connector insertion slot 1053a. The liquid connector insertion slot 1053a is fluidly connected to an ink supply flow channel formed inside the liquid ejector head 1000 and is connected to the first pressure regulating unit 1120 via the aforementioned filter 1110. Simultaneously, the liquid connector 1059a is located at the end of an ink supply tube 1059 connected to an external pump 1021, which pressurizes ink from the ink tank 2 to the liquid ejector head 1000.

[0208] As mentioned above, Figure 28 The liquid injection head 1000 shown is facilitated by using the liquid connection unit 1700 for attachment, removal, and replacement operations. However, if the sealing performance between the liquid connector insertion slot 1053a and the liquid connector 1059a deteriorates, ink supplied by the external pump 1021 may leak out of the liquid connection unit 1700. If the leaked ink adheres to the circulation pump 1500, etc., electrical systems, etc., may malfunction. In view of this situation, in this embodiment, the layout of the circulation pump, etc., is as described below.

[0209] <Layout of circulating pumps and others>

[0210] like Figure 28As shown, in this embodiment, the circulation pump 1500 is positioned above the liquid connector unit 1700 in the gravity direction to prevent ink from adhering to the circulation pump 1500 after leaking from the liquid connector unit 1700. Specifically, the circulation pump 1500 is positioned above the liquid connector insertion slot 1053a in the gravity direction, which serves as the liquid inlet of the liquid jet head 1000. Furthermore, the circulation pump 1500 is located in a position that does not contact the components constituting the liquid connector unit 1700. Therefore, even if ink leaks from the liquid connector unit 1700, the ink will flow in the horizontal direction, which is the opening direction of the liquid connector 1059a, or downward in the gravity direction. Thus, ink can be prevented from reaching the circulation pump 1500, which is positioned above in the gravity direction. In addition, since the circulation pump 1500 is located away from the liquid connector unit 1700, it is unlikely that ink will reach the circulation pump 1500 while flowing on other components.

[0211] Meanwhile, the electrical connection module 1515, which connects the circulation pump 1500 to the electrical contact plate 1006 via the flexible wiring member 1514, is positioned above the liquid connection unit 1700 in the direction of gravity. This configuration also reduces the chance of electrical failures due to ink leakage from the liquid connection unit 1700.

[0212] Meanwhile, the head housing 1053 is provided with a wall portion 1053b. Therefore, even when ink is ejected from the opening 1059b of the liquid connection unit 1700, the ink can be blocked and the chance of ink reaching the circulation pump 1500 or the electrical connection module 1515 can be reduced.

[0213] While this disclosure has been described with reference to exemplary embodiments, it should be understood that this disclosure is not limited to the disclosed exemplary embodiments. The scope of the following claims should be given the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.

Claims

1. A liquid jetting device, comprising: A printing element board includes an injection port and a pressure chamber communicating with the injection port, wherein the printing element board is configured to eject liquid from the injection port; A supply flow channel is provided on the printing element board and communicates with the pressure chamber; A flow collection channel is provided on the printed component board and communicates with the pressure chamber; A liquid supply mechanism is configured to generate a pressure difference between a supply flow channel and a collection flow channel, thereby supplying liquid from the supply flow channel to a pressure chamber and recovering liquid from the pressure chamber from the collection flow channel. The liquid supply mechanism includes a circulation unit, which includes a first pressure regulating mechanism, a second pressure regulating mechanism, and a circulation pump. The first bubble storage unit connects the supply flow channel to the first pressure regulating mechanism; and The second bubble storage unit connects the collection flow channel to the second pressure regulating mechanism. The volume of the first bubble storage unit is greater than the volume of the second bubble storage unit.

2. The liquid jetting device according to claim 1, wherein, The printing element board, the supply flow channel, the collection flow channel, and the liquid supply mechanism are disposed on the liquid injection head, which is mounted on a carriage and is movable.

3. The liquid jetting device according to claim 1, in, The first bubble storage unit includes a supply connection flow channel formed in the flow channel component to be stacked on the printed element board, and The second bubble storage unit includes a collection and connection flow channel formed in the flow channel component.

4. The liquid jetting device according to claim 1, in, The first bubble storage unit includes a first pressure regulating chamber capable of adjusting the pressure between the supply flow channel and the liquid supply mechanism, and The second bubble storage unit includes a second pressure regulating chamber capable of adjusting the pressure between the collection flow channel and the liquid supply mechanism.

5. The liquid jetting device according to claim 4, wherein, The first pressure regulating chamber and the second pressure regulating chamber are disposed in the circulation unit, which is connected to the flow channel components stacked on the printed element board.

6. The liquid jetting device according to claim 4, wherein, The volume of the first pressure regulating chamber is greater than the volume of the second pressure regulating chamber.

7. The liquid jetting device according to claim 4, in, The first pressure regulating chamber is connected to the second pressure regulating chamber via the liquid supply mechanism, and A bypass flow channel is provided between the first pressure regulating chamber and the second pressure regulating chamber, and the bypass flow channel is configured to connect the first pressure regulating chamber to the second pressure regulating chamber without inserting the liquid supply mechanism.

8. The liquid jetting device according to claim 4, wherein, The first pressure regulating chamber is connected to the liquid tank via a filter.

9. The liquid jetting device according to claim 1, wherein, The volume of the first bubble storage unit is at least 1.2 times the volume of the second bubble storage unit.

10. The liquid jetting device according to claim 1, wherein, Both the first bubble storage unit and the second bubble storage unit are provided with slits of a groove shape along the flow of the liquid flowing in the first bubble storage unit and the second bubble storage unit.

11. The liquid jetting device according to claim 10, wherein, The width of the slit is in the range of 0.2 to 0.5 mm.

12. The liquid jetting device according to claim 4, wherein, The flow channel connecting the supply flow channel to the first pressure regulating chamber extends in the vertical direction.

13. The liquid jetting device according to claim 4, in, The supply flow channel is connected to the flow channel of the first pressure regulating chamber at an angle relative to the direction of gravity, and The flow channel includes an inner wall, where the component of the normal vector at the inner wall has a component along the direction of gravity.

Images