Valve unit and cleaning method for the same

Abstract

To increase a rate of replacement of ink for inspecting with cleaning liquid during cleaning.SOLUTION: A valve unit 30 comprises: a pressure chamber 32; a supply chamber 45 configured to supply liquid to the pressure chamber 32, which comprises an opening part 45a; a valve member 51 configured to control a communication between the pressure chamber 32 and the supply chamber 45; a support member 40, provided to block the opening part 45a, which supports the valve member 51; a liquid passage 42 communicating with the supply chamber 45; a film 34B with flexibility covering a region including the opening part 45a provided with the support member 40; a clearance region 47 formed between an outer surface 40c of the support member 40 and the film 34B with flexibility and communicating with the liquid passage 42; and an inner passage 52 communicating between the clearance region 47 and the supply chamber 45.SELECTED DRAWING: Figure 7

Description

[Technical field]

[0001] The present invention relates to a valve unit for supplying liquid such as ink. [Background technology]

[0002] As an example of a valve unit used in a liquid ejection head, Patent Document 1 describes a valve unit that supplies liquid to a liquid ejection head. This valve unit has a pressure chamber, a supply chamber that supplies liquid to the pressure chamber, a valve for opening and closing a supply hole located between the supply chamber and the pressure chamber, and a flexible film that is displaced based on a negative pressure generated with a decrease in liquid in the pressure chamber. The valve is opened and closed by directly transmitting the displacement of the flexible film to the valve. A spring seat that supports a spring for driving the valve is fitted into the side wall of the supply chamber. The supply chamber is made into a closed space by covering an area including the part where the spring seat is fitted with a film member. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2003 / 041964 Summary of the Invention [Problem to be solved by the invention]

[0004] Generally, in the manufacturing process of a liquid ejection head, the ejection operation of the liquid ejection head is inspected. In this inspection, a test ink different from the printing ink is used. After the inspection, the inside of the liquid ejection head, including the valve unit, is washed with pure water. If the test ink remains in the valve unit during this washing process, it will cause a decrease in the ejection performance of the liquid ejection head. Therefore, in order to prevent a decrease in the ejection performance, it is important to increase the replacement rate of the test ink with pure water during washing. In the valve unit described in Patent Document 1, a part of the flow path that introduces liquid into the supply chamber is a dead end, making it difficult to circulate the liquid. Therefore, if the test ink enters the flow path during inspection of the liquid ejection head, the test ink remains in part of the flow path even after cleaning. As a result, the ejection performance of the liquid ejection head may be reduced.

[0005] An object of the present invention is to provide a valve unit capable of increasing the rate of replacement of test ink with cleaning liquid during cleaning. [Means for solving the problem]

[0006] In order to achieve the above-mentioned object, a valve unit according to one aspect of the present invention is characterized in having a pressure chamber, a supply chamber configured to supply liquid to the pressure chamber and having an opening, a valve member configured to control communication between the pressure chamber and the supply chamber, a support member arranged to block the opening and supporting the valve member, a liquid flow path communicating with the supply chamber, a flexible film covering an area including the opening in which the support member is arranged, a gap area formed between an outer surface of the support member and the flexible film, communicating with the liquid flow path, and an internal flow path communicating the gap area with the supply chamber. Effect of the Invention

[0007] According to the present invention, it is possible to increase the replacement rate of the test ink with the cleaning liquid when cleaning the valve unit. [Brief description of the drawings]

[0008] [Figure 1] 1 is a partial schematic diagram of an inkjet recording apparatus to which the present invention can be applied. [Diagram 2] 2 is a perspective view of a recording head mounted on the inkjet recording apparatus shown in FIG. [Diagram 3] FIG. 1 is a plan view of a valve unit according to a first embodiment of the present invention. [Figure 4]4 is a plan view showing a state in which the flexible film of the valve unit shown in FIG. 3 has been removed. FIG. [Diagram 5] FIG. 4 is a perspective view of the valve unit shown in FIG. 3. [Figure 6] FIG. 4 is an exploded perspective view of the valve unit shown in FIG. 3. [Figure 7] FIG. 4 is a partial cross-sectional view of the valve unit shown in FIG. [Figure 8] FIG. 2 is a schematic diagram for explaining a method for heat-welding a flexible film. [Figure 9] FIG. 1 is a schematic diagram illustrating an example of an ink filling system. [Figure 10] FIG. 1 is a schematic diagram illustrating an example of a cleaning system. [Figure 11] FIG. 4 is a plan view of a valve unit according to a comparative example. [Figure 12] FIG. 12 is a partial cross-sectional view of the valve unit shown in FIG. [Figure 13] FIG. 6 is a plan view of a valve unit according to a second embodiment of the present invention. [Figure 14] FIG. 11 is a plan view of a valve unit according to a third embodiment of the present invention. [Figure 15] FIG. 10 is a plan view of a valve unit according to a fourth embodiment of the present invention. [Figure 16] FIG. 2 is a schematic diagram for explaining a method for heat-welding a flexible film. [Figure 17] 10A to 10C are schematic diagrams for explaining another method for heat-welding a flexible film. [Figure 18] FIG. 13 is a plan view of a valve unit according to a fifth embodiment of the present invention. [Figure 19] FIG. 19 is a partial cross-sectional view of the valve unit shown in FIG. 18. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. However, the components described in the embodiment are merely examples and are not intended to limit the scope of the present invention.

[0010] First, an inkjet recording apparatus to which the present invention can be applied will be described. Fig. 1 is a schematic diagram of a main part of an inkjet recording apparatus 10 to which the present invention can be applied. Fig. 2 is a perspective view of a recording head 20 mounted on the inkjet recording apparatus 10.

[0011] 1, an inkjet recording device 10 has four ink tanks 11 in the device body. The four ink tanks 11 contain black, cyan, magenta, and yellow ink, which are examples of liquid. These ink tanks 11 are connected to four supply tubes 14 via joints 13. There is a one-to-one correspondence between each ink tank 11 and each supply tube 14. A pressure pump 12 pressure-feeds the ink contained in each ink tank 11 toward the corresponding supply tube 14. The carriage 15 reciprocates in the direction of the arrow X (hereinafter referred to as the main scanning direction) by the driving force of a drive motor (not shown). The recording medium P1 is transported in the direction of the arrow Y (hereinafter referred to as the sub-scanning direction) that intersects (for example, is perpendicular to) the main scanning direction by a transport mechanism (not shown). The carriage 15 carries the recording head 20 shown in FIG. 2. The recording head 20 is detachable.

[0012] The recording head 20 has a liquid ejection section 21 capable of ejecting ink, and an attachment section 22 capable of attaching six valve units 30. These valve units 30 are provided corresponding to the colors of ink. Two ink chambers are provided for each valve unit 30, into which ink can be introduced separately from two ink tanks 11, and an ink inlet 23 is formed for each ink chamber. Each inlet 23 is connected to the ink tank 11 of the corresponding ink color via a supply tube 14. Ink pumped from the ink tank 11 is introduced into the valve unit 30 from the inlet 23. The valve unit 30 applies a predetermined negative pressure to the introduced ink and supplies it to the liquid ejection section 21.

[0013] Although not shown in Fig. 2, the liquid ejection section 21 has a plurality of ejection port arrays provided corresponding to the colors of ink. In the ejection port array, a plurality of ejection port capable of ejecting ink is arranged in a line. Each ejection port array extends in a direction intersecting (for example, perpendicular to) the main scanning direction. Each ejection port is combined with an energy generating element that generates energy for ejecting ink. The energy generating element is, for example, an electrothermal conversion element (heater) or a piezoelectric element. An image is recorded on the recording medium P1 by alternately repeating an operation of the recording head 20 ejecting ink (scanning) while moving the carriage 15 in the main scanning direction and an operation of conveying the recording medium P1 in the sub-scanning direction. This recording operation is called a serial scan method.

[0014] During maintenance of the recording head 20, the carriage 15 moves to a position above the suction cap 16. The suction cap 16 can be raised and lowered by a drive source (not shown). The suction cap 16 caps the ejection port formation surface of the liquid ejection unit 21. By reducing the pressure inside the suction cap 16 with the suction pump 17, ink can be sucked and discharged from the ejection port of the liquid ejection unit 21 into the suction cap 16.

[0015] (First embodiment) 3 to 7 are diagrams for explaining the configuration of the valve unit 30 according to the first embodiment of the present invention. FIG. 3 shows the configuration of the valve unit 30, where FIG. 3(a) is a plan view and FIG. 3(b) is a partially enlarged view. FIG. 4 shows the valve unit 30 with the flexible film removed, where FIG. 3(a) is a plan view and FIG. 4(b) is a partially enlarged view. FIG. 5(a) and FIG. 5(b) are perspective views of the valve unit 30. FIG. 5(b) shows the valve unit 30 shown in FIG. 5(a) as viewed from the direction of the arrow I. In FIG. 5(a), the arrow Y indicates the main scanning direction, the arrow X indicates the sub-scanning direction, and the arrow A indicates the mounting direction to the mounting portion 22 shown in FIG. 2. FIG. 6 is an exploded perspective view of the valve unit 30 shown in FIG. 5(a). FIG. 7 is a partial cross-sectional view showing the structure of the cross section of the valve unit 30 shown in FIG. 3 taken along the line AA.

[0016] 3 to 6, the valve unit 30 has a unit case 31 in which two pressure chambers 32 each constituting a pressure adjustment mechanism are provided. As shown in Figures 5(a) and 5(b), the two pressure chambers 32 are arranged side by side in the Y direction intersecting (for example, perpendicular to) the A direction. One pressure chamber 32 opens to one side surface 31a of the unit case 31, and the other pressure chamber 32 opens to the other side surface 31b of the unit case 31. These pressure chambers 32 have the same structure except that they open in different directions. Below, the structure related to one pressure chamber 32 will be described, and a description of the other pressure chamber 32 will be omitted.

[0017] A film fixing surface 33 for attaching a flexible film 34A is provided at the opening of the pressure chamber 32. The opening of the pressure chamber 32 is closed by attaching the flexible film 34A to the film fixing surface 33. The flexible film 34A constitutes at least a part of the wall of the pressure chamber 32. In order to increase the volume of the pressure chamber 32, it is preferable that the part of the flexible film 34A that closes the opening has a convex shape that protrudes outward. It is preferable that the convex part of the flexible film 34A has a truncated cone shape, for example.

[0018] As shown in Figures 6 and 7, a pressure-receiving plate 35 is attached to the inner surface of flexible film 34A. Pressure-receiving plate 35 is fixed to flexible film 34A by thermal welding. A coil spring 36 is attached to the inner wall of pressure chamber 32. Coil spring 36 biases flexible film 34A toward the outside of pressure chamber 32 via pressure-receiving plate 35. Hereinafter, flexible film 34A equipped with pressure-receiving plate 35 will be referred to as flexible member 50.

[0019] A supply chamber 45 is formed in the unit case 31 at a position facing the pressure chamber 32 in the X direction. The supply hole 38 is in communication with the pressure chamber 32, and the supply chamber 45 supplies ink to the pressure chamber 32 via the supply hole 38. The supply chamber 45 has an opening 45a at a position facing the supply hole 38. The opening 45a is provided with a film fixing surface 43 for attaching a flexible film 34B that is separate from the flexible film 34A of the flexible member 50. A valve member 51 that opens and closes the supply hole 38 in response to the displacement of the flexible member 50 is provided inside the supply chamber 45, and a support member 40 that supports the valve member 51 is provided so as to close the opening 45a.

[0020] The valve member 51 controls communication between the pressure chamber 32 and the supply chamber 45. The valve member 51 has a valve body 37 capable of closing the supply hole 38, and a valve spring 39 that urges the valve body 37 toward the supply hole 38. The valve spring 39 is, for example, a coil spring. The valve body 37 is fixed to the support member 40 via the valve spring 39. The support member 40 has a support plate 40a that can be press-fitted into the opening 45a. A protrusion 40b into which the valve spring 39 is fitted is provided at the center of the inner surface of the support plate 40a. The outer diameter of the protrusion 40b is smaller than the inner diameter of the valve spring 39.

[0021] A part of the side surface 31b of the unit case 31 constitutes the outer wall surface of the supply chamber 45. The other flexible film 34B is attached to the film fixing surface 43 so as to cover at least an area of ​​the outer wall surface of the supply chamber 45 including the opening 45a where the support member 40 is provided. The supply chamber 45 communicates with the liquid flow path 42. The liquid flow path 42 communicates with the inlet 23 shown in FIG. 2. Ink pumped from the ink tank 11 is supplied to the liquid flow path 42 through the inlet 23. A part of the flow path wall of the liquid flow path 42 is open, and this opening is covered by the other flexible film 34B. That is, the other flexible film 34B constitutes a part of the flow path wall of the liquid flow path 42. Another flexible film 34B is a flexible film of the flexible member 50 in the other pressure chamber 32. That is, one flexible film 34A (or 34B) closes the opening of one pressure chamber 32, and also closes the opening 45a of the supply chamber 45 and the opening of the liquid flow path 42 that communicate with the other pressure chamber 32.

[0022] Between the outer surface 40c of the support member 40 and another flexible film 34B, a gap region 47 communicating with the liquid flow path 42 is formed. The support plate 40a is provided with a through hole 46 penetrating in the thickness direction. The through hole 46 is an example of an internal flow path 52 that communicates the gap region 47 with the supply chamber 45. In this embodiment, the through hole 46 is a first through hole penetrating the central part of the support plate 40a. More specifically, the first through hole 46 penetrates the protrusion 40b from the outer surface of the support plate 40a. Since the outer surface of the support plate 40a is the outer surface 40c of the support member 40, the outer surface of the support plate 40a will be referred to as the outer surface 40c below.

[0023] As shown in Figures 3 and 4, two welding ribs 41 to which another flexible film 34B is fixed by thermal welding are provided on the outer surface 40c of the support plate 40a. Each welding rib 41 is formed so as to protrude from the outer surface 40c of the support plate 40a. Each welding rib 41 extends in an arc shape so as to surround the through hole 47. The number and shape of the welding ribs 41 can be changed as appropriate.

[0024] FIG. 8 is a diagram for explaining a heat welding method for fixing the flexible film 34B by heat welding. FIG. 8(a) shows a state before heat welding, and FIG. 8(b) shows a state after heat welding. In FIG. 8(a), the film fixing surface 43a and the rib 41a are before heat welding, and correspond to the film fixing surface 43 and the welding rib 41, respectively. FIG. 8(a) and FIG. 8(b) show a structure corresponding to a cross section of the valve unit 30 shown in FIG. 3 taken along the line BB. Note that heat welding is performed with the flexible film 34B facing up, and therefore, FIG. 8(a) and FIG. 8(b) show a state in which the flexible film 34B faces up.

[0025] As shown in FIG. 8(a), two ribs 41a are provided on the outer surface 40c of the support plate 40a so as to surround the first through hole 46. If the ribs 41a are provided on the entire surface or the entire circumference of the outer surface 40c, the support plate 40a is less likely to deform when pressed in, and as a result, it becomes difficult to absorb the component tolerance when pressed in. For this reason, in this embodiment, the two ribs 41a are formed in an arc shape so as to surround the first through hole 46. When the support plate 40a is pressed into the opening 45a, it is preferable that the height h1 of each rib 41a from the outer surface 40c is equal to or greater than the height h2 of the film fixing surface 43a from the outer surface 40c.

[0026] The flexible film 34B is fixed by heat welding by contacting the film fixing surface 43a and the rib 41a and heating them at a high temperature. The film fixing surface 43a and the upper part of the rib 41a melt during heat welding, forming the film fixing surface 43 and the welded rib 41 as shown in Fig. 8(b). The height, width and arrangement of the rib 41a are set so that the resin melted by heat welding does not block the first through hole 46 or the gap region 47 formed around the welded rib 41.

[0027] As shown in FIG. 5(a), the film fixing surface 33 and the film fixing surface 43 are provided on the same side surface 31a, and the flexible film 33A is heat-welded to these film fixing surfaces 33, 43. Here, the film fixing surfaces 33, 43 before heat-welding are referred to as film fixing surfaces 33a, 43a. It is preferable that the film fixing surfaces 33a, 43a have the same height, and the rib 41a protrudes outward from the film fixing surfaces 33a, 43a. In this case, at the time of heat-welding, the flexible film 34A and the rib 41a are first fixed, and then the flexible film 34A and the film fixing surfaces 33a, 43a are fixed. According to this heat-welding process, the rib 41a acts to block the melted resin of the film fixing surfaces 33a, 43a from flowing toward the first through hole 46 at the time of heat-welding. A similar heat-welding process can be applied to the other side surface 31b shown in FIG. 5(b). In the above-mentioned heat welding process, if the flexible film 34A is first fixed to the film fixing surfaces 33a and 43a, the heat of the welding jig is lost, and the welding of the rib 41a becomes insufficient. As a result, the flexible film 34A may stretch and wrinkle. The above-mentioned heat welding process is effective from the viewpoint of suppressing the occurrence of such wrinkles.

[0028] Next, the operation of the valve unit 30 of this embodiment will be described with reference to Figures 1 to 7. Here, the operation of the valve unit 30 in a state where it is attached to the recording head 20 will be described. In the valve unit 30, each pressure chamber 32 communicates with a corresponding ejection port of the liquid ejection section 21 via an ink outlet path (not shown) formed in the mounting section 22 and the unit case 31. Also, each supply chamber 45 communicates with a corresponding inlet port via an ink introduction path (not shown) formed in the mounting section 22 and the unit case 31. With the valve member 51 blocking the supply hole 38, the ink in the pressure chamber 32 decreases as the ink is consumed by the recording head 20. When the negative pressure in the pressure chamber 32 increases as the ink decreases, the flexible film 34 deforms inward, and the pressure-receiving plate 35 comes into contact with the valve body 37 of the valve member 51.

[0029] When the negative pressure in the pressure chamber 32 increases to or exceeds a predetermined value, the pressure plate 35 pushes the valve body 37 to open it against the biasing force of the valve spring 39 that biases the valve body 37 in the closing direction. This creates a flow path between the step of the valve body 37 and the unit case 31, and ink flows into the pressure chamber 32 through the gap between the thin tip of the valve body 37 and the inner wall surface of the supply hole 38 and through the above-mentioned flow path. The inflow of ink increases the ink storage volume of the pressure chamber 32, and the negative pressure in the pressure chamber 32 decreases. As the negative pressure decreases, the flexible film 34A deforms outward, and the pressure plate 35 moves away from the valve body 37 of the valve member 51. As a result, the valve body 37 closes the supply hole 38 again. Through the above operation, the valve unit 30 can stably supply ink to the recording head 20 with a predetermined negative pressure applied thereto.

[0030] Next, a discharge performance test of the recording head 20 equipped with the valve unit 30 will be described. The recording head 20 equipped with the valve unit 30 is mounted on an ejection performance inspection machine, and ink is actually ejected from all of the ejection ports onto high-quality dedicated paper. Based on the position of the ink droplets that land on the high-quality dedicated paper, it is evaluated whether the ink droplets land within a predetermined accuracy. In consideration of the effect of ink volatilization after packaging the recording head 20 and reducing the cost of ink, a test ink different from the printing ink is used. The viscosity and other characteristics of the test ink are preferably equivalent to those of the printing ink. The color of the test ink is preferably a color suitable for visual inspection.

[0031] In the ejection performance test, first, the recording head 20 is filled with the test ink. FIG. 9 is a schematic diagram of the ink filling system. The tank 61a stores the test ink. The tank 61a supplies the test ink to the inlet 23 via the joint 56. The test ink is supplied from the inlet 23 to the inside of the recording head 20 via the valve unit 30. In order to quickly fill the test ink, the inside of the cap 55 capping the ejection port formation surface is depressurized by the vacuum pump 62a while the test ink is pumped from the tank 61a side. The test ink discharged from the ejection port is stored in the tank 63a provided between the cap 55 and the vacuum pump 62a. The test ink stored in the tank 63a is reused after passing through a filter (not shown).

[0032] The test ink is discharged from the discharge ports of the recording head 20 filled with the test ink, and the discharge performance is inspected. After the inspection, the recording head 20 is washed, including the valve unit 30. In this embodiment, pure water is used as the washing liquid in order to increase the replacement rate of the test ink with the washing liquid during washing. 10 is a schematic diagram of the cleaning system. Tank 61b stores pure water. Tank 61b is connected to inlet 23 via joint 56. Three-way valve 54 is provided between tank 61b and joint 56. Three-way valve 54 alternately switches between pure water and CDA (clean dry air).

[0033] In this cleaning system, first, the three-way valve 54 opens between the tank 61b and the joint 56. The tank 61b supplies pure water to the inlet 23 via the joint 56. The pure water is supplied from the inlet 23 to the inside of the recording head 20 via the valve unit 30. While the pure water is pumped from the tank 61b side, the inside of the cap 55 capping the ejection port formation surface is depressurized by the vacuum pump 62b. When the pure water passes through the valve unit 30 and the recording head 20, the remaining test ink and the pure water are mixed. The mixture of the test ink and the pure water is discharged from the ejection port and stored in the tank 63b. As a result, the amount of the test ink remaining in each of the valve unit 30 and the recording head 20 is reduced, and the concentration of the remaining test ink is also reduced.

[0034] After washing with pure water for a few seconds, the three-way valve 54 switches the supply to the joint 56 from pure water to air. The air is supplied from the inlet 23 through the valve unit 30 into the recording head 20. After the air is allowed to flow for a few seconds, the three-way valve 54 switches the supply to the joint 56 from air to pure water. By repeating the intermittent operation of alternately flowing pure water and air several times as described above, the pure water passing through the inside of the valve unit 30 and the recording head 20 becomes turbulent, thereby increasing the cleaning effect.

[0035] According to the valve unit 30 of this embodiment, it is possible to increase the replacement rate of the test ink with the cleaning liquid (pure water in this case) when cleaning the valve unit 30. This effect will be described in detail below. First, as a comparative example, valve unit 30A in which gap region 47 and supply chamber 45 do not communicate with each other will be given, and the problems that arise in this valve unit 30A will be specifically described.

[0036] (Comparative Example) Fig. 11 is a plan view of a valve unit 30A as a comparative example, and Fig. 12 is a partial cross-sectional view showing the cross-sectional structure of the valve unit 30A shown in Fig. 11 taken along line AA. Valve unit 30A of this comparative example differs from valve unit 30 of the first embodiment described above in that it does not have a first through hole 46 (internal flow path 52) that communicates gap region 47 and supply chamber 45. Gap region 47 communicates with liquid flow path 42, and the rear side opposite liquid flow path 42 is a dead end. A closed space 44 is formed at the rear side of gap region 47. The other components are basically the same as those of valve unit 30, so a description of those components will be omitted here.

[0037] The valve unit 30A was attached to the recording head 20, and the recording head 20 was filled with test ink using the ink filling system shown in Fig. 9. In the valve unit 30A, the test ink supplied from the inlet 23 passed through the supply chamber 45 and the pressure chamber 32 via the liquid flow path 42. At this time, the test ink also flowed from the liquid flow path 42 into the gap region 47. The test ink that flowed into the gap region 47 remained in the closed space 44.

[0038] Next, the recording head 20 including the valve unit 30A was washed using the cleaning system shown in FIG. 10. The intermittent operation of alternately flowing pure water and air was repeated several times to wash the valve unit 30A and the recording head 20 with pure water. In the valve unit 30A, the pure water supplied from the inlet 23 passed through the supply chamber 45 and the pressure chamber 32 via the liquid flow path 42. The remaining test ink mixed with the pure water, and the mixed water was discharged. However, since the gap region 47 has a structure that makes it difficult to circulate liquid, high-concentration test ink remained in the closed space 44 even after the intermittent operation was performed for about several minutes. Also, low-concentration test ink remained on the side of the gap region 47 close to the liquid flow path 42. In this way, in the valve unit 30A, the test ink remains in the gap region 47, and the remaining test ink may mix with or react with the printing ink, thereby degrading the ejection performance of the recording head 20. For example, the test ink may react with the printing ink to generate impurities that may affect the ejection performance of the liquid ejection head. Furthermore, the color of the ejected ink may change due to the mixing of the printing ink and the test ink, resulting in a deterioration in print quality.

[0039] In contrast, in the valve unit 30 of this embodiment, the gap region 47 communicates with the supply chamber 45 through the first through hole 46 of the support member 40, so that the liquid in the gap region can circulate (flow out). Therefore, when the intermittent operation of alternately flowing pure water and air is repeated several times, the test ink remaining in the gap region 47 flows into the common liquid chamber 45 through the first through hole 46. In addition, the pure water and air also flow into the common liquid chamber 45 from the gap region 47 through the first through hole 46. This liquid circulation allows most of the test ink remaining in the gap region 47 to be replaced with pure water, so that the replacement rate of the test ink with pure water during cleaning can be increased, and the deterioration of the ejection performance of the recording head 20 can be suppressed. In addition, the time required for cleaning can be shortened compared to the valve unit 30A of the comparative example.

[0040] In addition, by increasing the temperature of the pure water, the surface tension is reduced and the cleaning effect is increased, and as a result, the replacement rate of the test ink with the pure water is improved. However, when the temperature of the pure water is increased, the heat causes the flexible film 34A to stretch. When the flexible film 34A stretches, the movement amount of the valve body 37 increases accordingly, and the valve body 37 cannot open at a specified negative pressure. As a result, the negative pressure in the pressure chamber 32 increases, making it impossible to eject ink from the ejection port of the recording head 20, which may cause printing defects.

[0041] In the valve unit 30 of this embodiment, the first through hole 46 may be disposed in the region of the gap region 47 that is furthest from the liquid flow path 42 (the portion on the dead end side). This allows the liquid in the gap region to circulate efficiently. In this case, however, it is preferable to dispose the welding rib 41 so that the resin melted by thermal welding does not block the first through hole 46. In other words, the welding rib 41 can be disposed in any position as long as it does not block the first through hole 46.

[0042] Second embodiment Fig. 13 shows the configuration of a valve unit 30 according to a second embodiment of the present invention, with Fig. 13(a) being a plan view and Fig. 13(b) being a partially enlarged view, Fig. 13(a) shows a state in which flexible film 34A has been removed. 13(a) and 13(b), the valve unit 30 of this embodiment differs from that of the first embodiment in that it includes two second through holes 46a, 46b instead of the first through hole 46. The components other than the second through holes 46a, 46b are basically the same as those of the first embodiment, and therefore a description of those components will be omitted here.

[0043] The second through holes 46a, 46b are provided on the outer side of the welding rib 41 and each penetrates the support plate 40a in the thickness direction. The second through hole 46a is disposed in a region of the gap region 47 adjacent to the liquid flow path 42. The second through hole 46b is disposed in a region on the back side of the gap region 47. The region on the back side is the region farthest from the liquid flow path 42 (the portion on the dead-end side).

[0044] According to the valve unit 30 of this embodiment, the liquid that has flowed from the liquid flow path 42 into the gap region 47 flows through the second through holes 46a, 46b into the common liquid chamber 45. Since the gap region 47 allows the liquid to circulate in this manner, as in the first embodiment, the replacement rate of the test ink with pure water during cleaning can be increased, and the deterioration of the ejection performance of the recording head 20 can be suppressed.

[0045] In the valve unit 30 of the present embodiment, three or more second through holes may be provided on the outer side of the welding rib 41. By increasing the number of second through holes, the liquid in the gap region 47 can be circulated more easily. At least one of the multiple second through holes is preferably disposed in a region on the back side (dead end portion) of gap region 47. This allows the liquid in gap region 47 to circulate efficiently.

[0046] (Third embodiment) Fig. 14 shows the configuration of a valve unit 30 according to a third embodiment of the present invention, with Fig. 14(a) being a plan view and Fig. 14(b) being a partially enlarged view, Fig. 14(a) shows a state in which flexible film 34A has been removed. 14(a) and 14(b), the valve unit 30 of this embodiment differs from that of the first embodiment in that it has four second through holes 46a, 46b, 46c, and 46d. Since the components other than the second through holes 46a, 46b, 46c, and 46d are basically the same as those of the first embodiment, a description of those components will be omitted here.

[0047] The four second through holes 46a, 46b, 46c, and 46d are provided on the outer side of the welding rib 46 and each penetrates the support plate 40a in the thickness direction. The second through holes 46a and 46b are the same as those shown in FIG. 13. The second through hole 46c and the second through hole 46d are arranged to face each other with the welding rib 41 in between. In this embodiment, the four second through holes 46a, 46b, 46c, and 46d are arranged at approximately equal intervals along the outer periphery of the welding rib 41.

[0048] According to the valve unit 30 of the present embodiment, the liquid that has flowed from the liquid flow path 42 into the gap region 47 passes through the first through hole 46 and the four second through holes 46a, 46b, 46c, and 46d and flows into the common liquid chamber 45. Compared to the first and second embodiments, there are more liquid circulation paths in the gap region 47, so that the replacement rate of the test ink with pure water during cleaning can be further improved. In the valve unit 30 of this embodiment, the number of the second through holes may be three or five or more. However, it is preferable that at least one of the second through holes is disposed in the back region (the part on the dead end side) of the gap region 47. This allows the liquid in the gap region 47 to circulate efficiently.

[0049] (Fourth embodiment) Fig. 15 shows the configuration of a valve unit 30 according to a fourth embodiment of the present invention, with Fig. 15(a) being a plan view and Fig. 15(b) being a partially enlarged view, Fig. 15(a) shows a state in which flexible film 34A has been removed. 15(a) and 15(b), the valve unit 30 of this embodiment differs from that of the first embodiment in that it has two protrusions 48. The components other than the protrusions 48 are basically the same as those of the first embodiment, so a description of those components will be omitted here.

[0050] The two protruding portions 48 are provided between the two welding ribs 41 and the first through hole 46 so as to protrude from the outer surface 40c of the support plate 40a. The two protruding portions 48 are provided corresponding to the two welding ribs 41, respectively, and extend in an arc shape so as to surround the first through hole 46. The height of the protruding portion 48 from the outer surface 40c is lower than the height of the welding rib 41 from the outer surface 40c. The number of the welding ribs 41 is not limited to two. Three or more welding ribs 41 may be formed so as to surround the first through hole 46. Similarly, the number of the protruding portions 48 is not limited to two. Three or more protruding portions 48 may be formed so as to surround the first through hole 46.

[0051] According to the valve unit 30 of this embodiment, in addition to providing the same effects as in the first embodiment, by providing the protrusion 48, the following effects are provided.

[0052] FIG. 16 is a diagram for explaining a method of fixing the flexible film 34B by heat welding. FIG. 16(a) shows the state before heat welding, and FIG. 16(b) shows the state after heat welding. In FIG. 16(a), the film fixing surface 43a and the rib 41a are before heat welding, and correspond to the film fixing surface 43 and the welding rib 41, respectively. FIG. 16(a) and FIG. 16(b) show a structure corresponding to the cross section of the valve unit 30 shown in FIG. 15 taken along the line AA. Note that heat welding is performed with the flexible film 34B facing up, and therefore, FIG. 16(a) and FIG. 16(b) show the state with the flexible film 34B facing up.

[0053] 16(a), two ribs 41a and two protrusions 48 are formed in an arc shape so as to surround the first through-hole 46. When the support plate 40a is press-fitted into the opening 45a, the height h1 of the rib 41a from the outer surface 40c is preferably equal to or greater than the height h2 of the film fixing surface 43a from the outer surface 40c. The height h3 of the protrusions 48 from the outer surface 40c is smaller than the height h1 of the rib 41a from the outer surface 40c.

[0054] The flexible film 34B is fixed by heat welding by contacting the film fixing surface 43a and the rib 41a and heating at a high temperature. At this time, the protrusion 48 and the flexible film 34B are not in contact with each other. During heat welding, the film fixing surface 43a and the upper part of the rib 41a melt, and the film fixing surface 43 and the welded rib 41 are formed as shown in FIG. 16(b). The melted resin of the rib 41a flows along the outer side wall and the inner side wall of the rib 41a. The resin that flows along the inner side wall of the rib 41a is blocked by the protrusion 48. This makes it possible to prevent the resin melted by heat welding from blocking the first through hole 46.

[0055] In addition, since the ribs 41a are welded by applying heat and load, the resin melted by the heat welding is blocked by the protrusions 48 and spreads in the in-plane direction of the flexible film 34B. As a result, the welding area between the welding ribs 41 and the flexible film 34B increases, and the bonding strength between the welding ribs 41 and the flexible film 34B can be increased.

[0056] FIG. 17 is a diagram for explaining another method of fixing the flexible film 34B by heat welding. FIG. 17(a) shows the state before heat welding, and FIG. 17(b) shows the state after heat welding. In FIG. 17(a), the film fixing surface 43a and the rib 41b are before heat welding, and correspond to the film fixing surface 43 and the welding rib 41, respectively. FIG. 17(a) and FIG. 17(b) show a structure corresponding to the cross section of the valve unit 30 shown in FIG. 15 taken along the line AA. Note that heat welding is performed with the flexible film 34B facing up, and therefore, FIG. 17(a) and FIG. 17(b) show the state with the flexible film 34B facing up.

[0057] As shown in Fig. 17(a), two ribs 41b and two protrusions 48 are formed in an arc shape so as to surround the first through-hole 46. The configuration other than the ribs 41b is the same as that shown in Fig. 16(a). The rib 41b is formed so that the inner side wall is almost perpendicular to the outer surface 40c of the support plate 40a, and the outer side wall is formed so as to be inclined with respect to the outer surface 40c of the support plate 40a. The rib 41b has a triangular (more preferably right-angled triangular) cross-sectional structure consisting of an almost perpendicular surface and an inclined surface. When the support plate 40a is press-fitted into the opening 45a, the height h1 of the rib 41b from the outer surface 40c is preferably equal to or greater than the height h2 of the film fixing surface 43a from the outer surface 40c. The height h3 of the protrusion 48 from the outer surface 40c is lower than the height h1 of the rib 41b from the outer surface 40c.

[0058] As in the heat welding method shown in Fig. 16, the flexible film 34B is brought into contact with the film fixing surface 43a and the rib 41b and heated at a high temperature, thereby fixing the flexible film 34B by heat welding. During heat welding, the film fixing surface 43a and the upper part of the rib 41b melt, forming the film fixing surface 43 and the welding rib 41 as shown in Fig. 17(b). The welding rib 41 has an outer side wall formed of an inclined surface and an inner side wall formed of a curved surface that protrudes toward the convex portion 48. Most of the melted resin in the rib 41b flows down the inner side wall of the rib 41b. The resin that flows down the inner side wall of the rib 41b is blocked by the protrusion 48. This makes it possible to prevent the melted resin from blocking the first through hole 46 due to thermal welding.

[0059] In addition, the resin melted by thermal welding is blocked by the convex portion 48 and spreads in the in-plane direction of the flexible film 34B, thereby increasing the welding area between the welding rib 41 and the flexible film 34B and increasing the bonding strength between the welding rib 41 and the flexible film 34B. Furthermore, compared with rib 41a having a rectangular cross-sectional shape, rib 41b having a triangular cross-sectional shape melts a smaller amount of resin by thermal welding, so that the space (part of gap region 47) formed on the outside and inside of welded rib 41 can be made larger. This makes it easier for liquid in gap region 47 to circulate. In addition, most of the resin melted by heat welding flows down the inner sidewall of the rib 41b. Therefore, the space (part of the gap region 47) formed outside the welding rib 41 becomes larger than that shown in Fig. 16(b). This makes it easier for the liquid in the gap region 47 to circulate.

[0060] Fifth embodiment Fig. 18 shows the configuration of a valve unit 30 according to a fifth embodiment of the present invention, with Fig. 18(a) being a plan view and Fig. 18(b) being a partially enlarged view. Fig. 19 is a partial cross-sectional view showing the cross-sectional structure of the valve unit 30 shown in Fig. 18(a) taken along line AA. The valve unit 30 of this embodiment differs from that of the first embodiment in that it has a flow path 46A instead of the first through hole 46. Since the other components other than the flow path 46A are the same as those of the first embodiment, a description of the other components will be omitted here.

[0061] Flow path 46A is an example of internal flow path 52 that connects gap region 47 and supply chamber 45. Flow path 46A extends along the boundary between the side surface of support plate 40a and the inner wall surface of opening 45a, and connects gap region 47 and supply chamber 45. Flow path 46A is composed of a groove provided on one or both of the side surface of support plate 40a and the inner wall surface of opening 45a. Flow path 46A opens to the back side (dead end portion) of gap region 47. According to the valve unit 30 of this embodiment, the liquid that has flowed from the liquid flow path 42 into the gap region 47 flows through the flow path 46A into the common liquid chamber 45. Since the gap region 47 allows the liquid to circulate in this manner, as in the first embodiment, the replacement rate of the test ink with pure water during cleaning can be increased, and the deterioration of the ejection performance of the recording head 20 can be suppressed.

[0062] In the valve unit 30 of this embodiment, two or more flow paths 46A may be provided. However, it is preferable that at least one of the flow paths 46A is disposed in the back region (dead end portion) of the gap region 47. This allows the liquid in the gap region 47 to circulate efficiently. Also, the first through-hole 46 may be provided in the support member 40a. By using the flow path 46A and the first through-hole 46 in combination, the liquid in the gap region 47 can be circulated more easily.

[0063] The first to fifth embodiments described above are merely examples of the present invention, and the components described in each embodiment may be combined as appropriate. For example, two or more of the first through-hole 46, the second through-holes (46a to 46d), and the flow path 46A may be combined, and the welding rib 41 and the protrusion 48 may be further combined with these combinations.

[0064] Disclosure of embodiments of the present invention includes the following configurations and methods. (Configuration 1) A pressure chamber; a supply chamber configured to supply liquid to the pressure chamber and having an opening; a valve member configured to control communication between the pressure chamber and the supply chamber; a support member provided to close the opening and supporting the valve member; a liquid flow path communicating with the supply chamber; a flexible film covering an area including the opening where the support member is provided; a gap region formed between an outer surface of the support member and the flexible film, the gap region communicating with the liquid flow path; an internal flow passage connecting the gap region and the supply chamber. (Configuration 2) The support member has a support plate configured to be press-fitted into the opening, 2. The valve unit according to claim 1, wherein the internal flow passage includes a through hole passing through the support plate in a thickness direction. (Configuration 3) 3. The valve unit of claim 2, wherein the through holes include a first through hole that penetrates a central portion of the support plate. (Configuration 4) 4. The valve unit according to claim 3, wherein a protrusion for mounting the valve member is provided at a center of an inner surface of the support plate, and the first through hole passes through the protrusion. (Configuration 5) The flexible film is welded to a plurality of welding ribs provided so as to protrude from an outer surface of the support plate, 5. The valve unit according to claim 3, wherein the plurality of welding ribs extend so as to surround the first through hole. (Configuration 6) Further, a plurality of protrusions are provided between the plurality of welding ribs and the first through hole so as to protrude from the outer surface of the support plate, The valve unit described in configuration 5, wherein the plurality of protrusions are provided corresponding to the plurality of welding ribs, respectively, extend to surround the first through hole, and a height of each protrusion from the outer surface is lower than a height of each of the plurality of welding ribs from the outer surface. (Configuration 7) 7. The valve unit according to configuration 6, wherein the plurality of welding ribs have outer side walls each formed as an inclined surface and inner side walls each formed as a curved surface protruding toward the protruding portion. (Configuration 8) The valve unit according to any one of configurations 5 to 7, wherein the through holes are provided outside the plurality of welding ribs and further include a plurality of second through holes penetrating the support plate in a thickness direction. (Configuration 9) the gap region is a dead end; 9. The valve unit according to claim 8, wherein at least one of the plurality of second through holes is provided in the dead-end portion of the support plate. (Configuration 10) The flexible film is welded to a plurality of welding ribs provided so as to protrude from an outer surface of the support plate, The plurality of welding ribs extend so as to surround a central portion of the outer surface, The valve unit according to configuration 2, wherein the through holes are provided outside the plurality of welding ribs and are a plurality of through holes penetrating the support plate in a thickness direction. (Configuration 11) the gap region is a dead end; 11. The valve unit according to claim 10, wherein one of the plurality of through holes is provided in the dead-end portion of the support plate. (Configuration 12) The support member has a support plate that can be press-fitted into the opening, The valve unit according to configuration 1, wherein the internal flow passage includes at least one flow passage extending along a boundary between a side surface of the support plate and an inner wall surface of the opening. (Configuration 13) 13. The valve unit according to claim 12, wherein the at least one flow passage is formed of a groove provided in one or both of a side surface of the support plate and an inner wall surface of the opening. (Configuration 14) the gap region is a dead end; 14. The valve unit of claim 12 or 13, wherein the at least one flow passage opens into the dead-end portion. (Configuration 15) A valve unit according to any one of configurations 1 to 14, a mounting portion to which the valve unit is detachably attached; A liquid ejection unit that ejects liquid, A liquid ejection head in which liquid is supplied to the liquid ejection portion via the valve unit attached to the mounting portion. (Method 1) A method for cleaning a valve unit according to any one of configurations 1 to 14, comprising the steps of: A method for cleaning a valve unit, comprising alternately supplying a cleaning liquid and air to the valve unit filled with test ink, thereby causing the test ink in the gap area to flow out of the internal flow path. (Method 2) A thermal welding method for press-fitting a support plate for supporting a valve member into an opening, and thermally welding a flexible film to the opening into which the support plate is pressed, comprising the steps of: the support plate has a through hole in the center, and an outer surface of the support plate is provided with a plurality of ribs protruding from the outer surface and extending to surround the through hole, and a plurality of protrusions are provided between the plurality of ribs and the through hole and protruding from the outer surface and extending to surround the through hole, the plurality of ribs have an inner side wall that is approximately perpendicular to the outer surface and an outer side wall that has a triangular cross-sectional structure consisting of an inclined surface inclined relative to the outer surface, and the height of the plurality of protrusions from the outer surface is configured to be lower than the height of the plurality of ribs from the outer surface, A thermal welding method comprising contacting the flexible film with the plurality of ribs and heating the flexible film to melt and thermally weld the upper portions of the ribs. [Explanation of symbols]

[0065] 30 Valve unit 32 Pressure Chamber 34 Flexible Film 38 Supply hole 40 Support member 42 Liquid flow path 45 Supply room 45a opening 47 Gap Area 50 Flexible member 51 Valve member 52 Internal flow path

Claims

1. A pressure chamber; a supply chamber configured to supply liquid to the pressure chamber and having an opening; a valve member configured to control communication between the pressure chamber and the supply chamber; a support member that is provided to close the opening and supports the valve member; a liquid flow path communicating with the supply chamber; a flexible film covering an area including the opening where the support member is provided; a gap region formed between the outer surface of the support member and the flexible film, the gap region communicating with the liquid flow path; an internal flow path that communicates the gap region with the supply chamber; the support member has a support plate configured to be press-fittable into the opening, The valve unit according to claim 1, wherein the internal flow path includes a through-hole that penetrates the support plate in a thickness direction.

2. The valve unit according to claim 1 , wherein the through holes include a first through hole that penetrates a central portion of the support plate.

3. 3. The valve unit according to claim 2, wherein a protrusion for attaching the valve member is provided at a center of an inner surface of the support plate, and the first through-hole passes through the protrusion.

4. The flexible film is welded to a plurality of welding ribs provided so as to protrude from the outer surface of the support plate, The valve unit according to claim 2 , wherein the plurality of welding ribs extend so as to surround the first through hole.

5. a plurality of protrusions provided between the plurality of welding ribs and the first through-holes so as to protrude from the outer surface of the support plate; 5. The valve unit according to claim 4, wherein the plurality of protrusions are provided corresponding to the plurality of welding ribs, respectively, extend to surround the first through hole, and a height of each protrusion from the outer surface is lower than a height of each of the plurality of welding ribs from the outer surface.

6. 6. The valve unit according to claim 5, wherein each of said plurality of welding ribs has an outer side wall formed of an inclined surface and an inner side wall formed of a curved surface that protrudes toward said convex portion.

7. The valve unit according to claim 4 , wherein the through holes further include a plurality of second through holes that are provided outside the plurality of welding ribs and penetrate the support plate in a thickness direction.

8. the gap region is a dead end, The valve unit according to claim 7 , wherein at least one of the plurality of second through holes is provided in the dead-end portion of the support plate.

9. The flexible film is welded to a plurality of welding ribs provided so as to protrude from the outer surface of the support plate, the plurality of welding ribs extend so as to surround a central portion of the outer surface; The valve unit according to claim 1 , wherein the through holes are a plurality of through holes provided outside the plurality of welding ribs and penetrating the support plate in a thickness direction.

10. the gap region is a dead end, The valve unit according to claim 9 , wherein one of the plurality of through holes is provided in the dead-end portion of the support plate.

11. A valve unit as described in claim 1, wherein the internal flow path includes at least one flow path extending along the boundary between the side of the support plate and the inner wall surface of the opening.

12. The valve unit according to claim 11, wherein the at least one flow path is formed by a groove provided in one or both of a side surface of the support plate and an inner wall surface of the opening.

13. the gap region is a dead end, The valve unit according to claim 11, wherein the at least one flow passage opens into the dead end portion.

14. A valve unit according to any one of claims 1 to 13; a mounting portion to which the valve unit is detachably attached; a liquid ejection unit that ejects a liquid, a liquid ejection head in which liquid is supplied to the liquid ejection section via the valve unit attached to the attachment section;

15. A method for cleaning a valve unit according to any one of claims 1 to 13, comprising the steps of: A method for cleaning a valve unit, comprising alternately supplying cleaning liquid and air to the valve unit filled with test ink, thereby causing the test ink in the gap area to flow out of the internal flow path.

16. A thermal welding method comprising: press-fitting a support plate supporting a valve member into an opening of a supply chamber configured to supply liquid to a pressure chamber; and thermally welding a flexible film to the opening into which the support plate is press-fitted, the support plate has a through hole in the center, and an outer surface of the support plate has a plurality of ribs that protrude from the outer surface and extend to surround the through hole, and a plurality of protrusions that protrude from the outer surface between the plurality of ribs and the through hole and extend to surround the through hole, the plurality of ribs have a triangular cross-sectional structure with an inner side wall that is approximately perpendicular to the outer surface and an outer side wall that is an inclined surface inclined relative to the outer surface, and the height of the plurality of protrusions from the outer surface is configured to be lower than the height of the plurality of ribs from the outer surface, an internal flow passage formed between the outer surface of the support plate and the flexible film, the internal flow passage communicating the gap region with the supply chamber, the internal flow passage including the through hole; A thermal welding method characterized by contacting the flexible film with the plurality of ribs and heating the flexible film to melt and heat-weld the upper portions of the ribs.

Images