Liquid discharge head and film member

Abstract

To provide a liquid discharge head and a film member which can improve performance in suppressing pressure fluctuation of liquid in a liquid supply head.SOLUTION: A liquid discharge head comprises: a discharge port configured to discharge liquid; a recording element configured to discharge liquid through the discharge port; a flow path configured to supply the liquid to the discharge port; and a film member provided in the flow path. The film member has a corrugated structure in which a plurality of annular convex parts and annular concave parts are formed alternately. When viewed from a direction perpendicular to a surface of the film member, the corrugated structure is formed in a ring shape having a straight portion.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a liquid ejection head and a membrane member. [Background technology]

[0002] In general, liquid ejection recording devices such as inkjet printers eject liquid such as ink from a liquid ejection head to perform recording on a recording medium such as paper. The liquid ejection head may be equipped with a damper mechanism that reduces pressure fluctuations of the ink inside the liquid ejection head in order to stabilize the ejection of the liquid and perform high-definition recording.

[0003] Patent Document 1 discloses a damper device including a flexible member constituted by annular bellows and having a plurality of annular regions having the same center but different degrees of deformation. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2014-188924 A Summary of the Invention [Problem to be solved by the invention]

[0005] The damper device of Patent Document 1, which is equipped with a member having a circular bellows structure, may not be able to sufficiently reduce pressure fluctuations in the liquid when the internal pressure of the liquid chamber increases due to an increase in printing speed, for example.

[0006] SUMMARY OF THE PRESENTLY PREFERRED EMBODIMENTS The present invention is directed to solving the above-mentioned problems, and has an object to provide a liquid ejection head and a membrane member that can improve the performance of suppressing pressure fluctuations of the liquid inside the liquid supply head. [Means for solving the problem]

[0007] The present invention, which solves the above-mentioned problems, provides a liquid ejection head having an ejection port configured to eject liquid, a recording element configured to eject liquid from the ejection port, a flow path configured to supply the liquid to the ejection port, and a membrane member provided within the flow path, wherein the membrane member has a wave-shaped structure in which a plurality of annular convex portions and annular concave portions are formed alternately, and when viewed from a direction perpendicular to the surface of the membrane member, the wave structure is a ring shape having a straight portion. Effect of the Invention

[0008] According to the present invention, it is possible to provide a liquid ejection head and a membrane member that are capable of improving the performance of suppressing pressure fluctuations of the liquid inside the liquid supply head. [Brief description of the drawings]

[0009] [Figure 1] 1 is a perspective view of a recording apparatus according to an embodiment of the present invention. [Diagram 2] FIG. 2 is an exploded perspective view of a liquid supply unit according to an embodiment of the present invention. [Diagram 3] 2 is a cross-sectional view of a liquid supply unit according to an embodiment of the present invention. [Figure 4] 2 is a cross-sectional view of a liquid supply unit according to an embodiment of the present invention. [Diagram 5] 1A and 1B are a front view and a cross-sectional view of a damper member according to an embodiment of the present invention. [Figure 6] FIG. 2 is a front view of a damper member according to an embodiment of the present invention. [Figure 7] FIG. 11 is a front view of a damper member according to a comparative example of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] An embodiment of the present invention will be described below with reference to the drawings. However, the following description does not limit the scope of the present invention. As an example, the present embodiment employs a method of discharging liquid by driving a piezoelectric element as a recording element. However, the present invention can also be applied to liquid discharge heads that employ a thermal method of discharging liquid by bubbles generated by a heater element, and various other liquid discharge methods.

[0011] Although the present embodiment is an inkjet recording apparatus (recording apparatus) in a form in which liquid such as ink is circulated between a tank and a liquid ejection head, the ink flow within the recording apparatus may be in other forms. For example, instead of circulating the ink, two tanks may be provided on the upstream side and downstream side of the liquid ejection head, and the ink may flow from one tank to the other tank to cause the ink to flow within the pressure chamber.

[0012] FIG. 1 shows an example of a recording device 10 (hereinafter also referred to as the device body) that is a one-pass type that records an image on a recording medium by moving the recording medium once, and has nozzles arranged on a side corresponding to the full width of the recording medium 20. The recording medium 20 is transported in the direction of arrow A by a transport unit 11, and recording is performed by a liquid ejection head 100. The liquid ejection head according to the present invention can be embodied in any form including the example of FIG. 1, and is not limited to other forms. In this specification, the direction parallel to the transport direction A of the recording medium 20 is defined as the Y direction, the direction perpendicular to the transport direction of the head is defined as the X direction, and the direction perpendicular to both the Y direction and the X direction, from the liquid ejection head 100 toward the recording medium 20, is defined as the Z direction.

[0013] The configuration of the liquid ejection head 100 according to this embodiment will be described.

[0014] The liquid ejection head 100 is a liquid ejection head in which a recording element substrate capable of ejecting liquid is disposed on a support member. The liquid ejection head 100 is positioned in the recording device 10 by a reference member. FIG. 1 shows a recording device 10 equipped with eight liquid ejection heads 100 (100Ka, 100Kb, 100Ya, 100Yb, 100Ma, 100Mb, 100Ca, 100Cb). The liquid ejection head 100 has a liquid connection part 501 and a refrigerant connection part on the top thereof, which are connected to a liquid supply part and a refrigerant supply part on the recording device 10 side, respectively, to supply liquid such as ink and a refrigerant into the liquid ejection head 100. The liquid supply part on the recording device side refers to a liquid supply path from a liquid container such as an ink cartridge mounted on the recording device to the liquid connection part 501 of the recording head 100. The liquid ejection head 100 has a liquid ejection unit equipped with a recording element substrate having recording elements such as piezoelectric elements for ejecting liquid, an electric wiring substrate connected to the liquid ejection unit, a support unit including a support member for supporting the liquid ejection unit, a liquid supply unit 500 that supplies liquid to the liquid ejection unit via the support unit, and a cooling unit for cooling drive circuits such as the electric wiring substrate. The configuration of each part of the liquid ejection head 100 will be described below.

[0015] The device main body and the recording element substrate are electrically connected via a flexible wiring substrate and an electric wiring substrate. The electric wiring substrate is electrically connected to the control unit of the device main body by an electric connection terminal, and supplies the recording element substrate with an ejection drive signal and power required for ejection. The electric connection substrate and the flexible wiring substrate are electrically connected by an electric connection portion. By consolidating the wiring by the electric circuit in the electric wiring substrate, the number of terminals of the electric connection terminal can be made smaller than the number of terminals of the recording element substrate. This has the effect of reducing the number of electric connection portions that need to be removed when assembling the liquid ejection head 100 to the recording device or when replacing the liquid ejection head.

[0016] The liquid ejection unit includes a recording element substrate that ejects liquid, a recording element substrate flow path member that supplies liquid to the recording element substrate, a flexible wiring substrate that is electrically connected to the flow path member and the recording element substrate, and a recording element substrate support member that is joined to the ejection surface side of the recording element substrate. In addition, the flexible wiring substrate is provided with a drive circuit board for driving the recording elements of the recording element substrate.

[0017] The support unit has a support member to which the liquid ejection units are joined, and a liquid supply member in which a flow path is formed to supply liquid to each liquid ejection unit via the support member. It is preferable that the support member and the liquid supply member are made of the same material or materials having similar linear expansion coefficients are selected, taking into consideration the influence of thermal expansion due to, for example, heating and temperature control of the liquid or environmental fluctuations. This makes it possible to suppress deformation of the entire support unit due to thermal expansion and the associated deterioration in the positional accuracy of the recording element substrate.

[0018] FIG. 2 is an exploded perspective view of the liquid supply unit 500, FIG. 3 is a cross-sectional view of the flow path forming member 510 in the XZ plane, and FIG. 4 is a cross-sectional view of the flow path forming member 510 in the YZ plane. The direction of the arrow in FIG. 3 indicates the flow direction of the liquid. The liquid supply unit 500 has two liquid connection parts 501 and is connected to a liquid supply system of the device body. This allows the liquid to be supplied from the liquid supply system of the device body to the liquid ejection head 100, and the liquid that has passed through the liquid ejection head 100 is recovered to the supply system of the device body. In this way, the liquid is configured to be circulated through the liquid supply path of the recording device body and the path of the liquid ejection head 100. The liquid that flows in from the device body side through the liquid connection part 501 is supplied to the liquid ejection unit through the communication port 502. The liquid that flows in through the communication port is supplied to the recording element substrate, and is ejected from the ejection port 213 by the piezoelectric element 212 as a recording element that supplies energy for ejecting the liquid to the ejection port.

[0019] The liquid supply unit 500 will now be described in more detail.

[0020] A filter 504 is attached to the flow path forming member 510 for the purpose of collecting foreign matter in the liquid flow path. The filter 504 is provided in a space surrounded by the flow path forming member 510 and a damper member 506 described later. In this embodiment, the filter 504 is disposed at an angle to the Z direction. This reduces the head width in the Y direction of the liquid ejection head 100 and increases the effective area of ​​the filter 504, thereby obtaining the effect of reducing pressure loss in the liquid path. From the viewpoint of reducing the head width, the angle of the filter 504 is preferably inclined from 3° to 20° to the Z direction, but the filter 504 may be disposed approximately parallel to the Z direction. The liquid in the flow path forming member 510 flows from the supply flow path 515 into the front liquid chamber 513, flows through the filter 504 to the rear liquid chamber 514, and flows through the communication port 502 to the support unit and the liquid ejection unit. Thereafter, the liquid circulates inside the recording element substrate, and is connected to the liquid supply system of the device main body through the communication port 502 and the recovery flow path 516. As shown in FIG. 3, the flow path forming member 510 is provided with a bypass flow path 512. The bypass flow path 512 is a flow path that directly connects the rear liquid chamber 514 and the recovery flow path 516, and is provided to remove air that has accumulated in the rear liquid chamber 514. For the same purpose, a flow path that connects the front liquid chamber 513 and the recovery flow path 516 may be provided. A flow path cover member 509 is attached to the flow path forming member 510, and the supply flow path 515 and the recovery flow path 516 are formed by the flow path forming member 510 and the flow path cover member 509. The method of attaching the flow path cover member 509 includes, for example, joining by ultrasonic welding, but the attachment method is not limited thereto. The flow path forming member 510 and the flow path cover member 509 may be molded integrally.

[0021] A film-like damper member 506 is provided on the flow path forming member 510, and is fixed together with a cover member 507 by screws 508. The contact portion between the flow path forming member 510 and the damper member 506 is sealed by an elastic member 505.

[0022] The damper member 506, which is a film-shaped membrane member, is a deformable member configured to deform in response to pressure fluctuations in the liquid chambers of the flow path forming member 510, and reduces pressure fluctuations of the liquid in the flow path by changing the volume of the liquid chambers (front liquid chamber 513 and rear liquid chamber 514). The operation of the damper member 506 will be described later.

[0023] From the viewpoint of strength and damping performance, the film thickness of the damper member 506 is preferably 10 μm or more and 500 μm or less, and more preferably 30 μm or more and 300 μm or less.

[0024] FIG. 5(A) is a front view of the damper member 506, FIG. 5(B) is an AA cross-sectional view of the damper member 506, and FIG. 5(C) is an enlarged view of the dotted line portion of FIG. 5(B). As shown in FIG. 5, the damper member 506 has a wave-shaped structure 5053 in which a plurality of annular convex portions and annular concave portions are alternately formed, and when viewed from a direction perpendicular to the surface of the damper member 506, the wave-shaped structure 5053 is in a ring shape having a straight portion 5052 and a curved portion 5051. In this embodiment, the shape of the wave-shaped structure 5053 is a rounded rectangle having four curved portions 5051 and four straight portions 5052. The straight portion 5053 refers to an area in which a plurality of convex portions and concave portions are arranged in parallel in the wave-shaped structure 5053. In FIG. 5 and FIG. 6 and FIG. 7 described later, the boundary between the straight portion 5053 and the curved portion 5051 is shown by a straight line for convenience. The corrugated structure 5053 can be formed into the damper member 506 by, for example, thermoforming. When the damper member 506 is deformed by the pressure of the liquid in the liquid chamber, the corrugated structure 5053 is deformed to change the volume of the liquid chamber, thereby mitigating the pressure fluctuation of the liquid. The damper performance is expressed by the volume change (compliance) per unit pressure, and the larger the volume change per unit pressure, that is, the easier the corrugated structure is to deform, the higher the damper performance is. In the case of the conventional corrugated structure 5053 having a circular shape without a straight portion as shown in FIG. 7, the rigidity of the circle is large, so that the amount of change in the corrugated structure 5053 decreases as the absolute value of the pressure in the liquid chamber increases, and the compliance also decreases. On the other hand, in the present invention, the annular corrugated structure has a straight portion 5052, so that the amount of deformation of the corrugated structure 5053 does not decrease even if the absolute value of the pressure in the liquid chamber increases, and a damper member with high compliance can be provided.

[0025] From the viewpoint of obtaining an appropriate compliance, the size of the annular corrugated structure 5053 (widths C and D in FIG. 5) is preferably such that the length of the short side is 15 mm or more. Also, as shown in FIG. 6(C), the lengths of the short side and the long side may be equal. Similarly, from the viewpoint of compliance, the length of the straight portion 5052 is preferably 2.0 mm or more.

[0026] In the present embodiment shown in FIG. 5, the corrugated structure 5053 is a rounded rectangle, but the shape of the annular corrugated structure 5053 may be other shapes as long as it has a straight portion 5052. For example, it may have a straight portion 5052 in only one direction on a plane as shown in FIG. 6(E). It may also have a rounded triangle shape having three curved portions 5051 and three straight portions 5052 as shown in FIG. 6(F). It may also have a corrugated structure composed only of straight portions 5052 without curved portions 5051. However, among various annular corrugated structures, a rounded rectangle shape having straight portions 5052 in both the X direction and the Z direction as shown in FIG. 5 and including multiple curved portions 5051 and multiple straight portions 5052 is preferable because it can obtain a particularly large compliance.

[0027] As shown in FIG. 5(C), when viewed from a direction parallel to the surface 506 of the damper member, the corrugated structure 5053 has a plurality of recesses and protrusions, in other words, it has a bellows shape in which valley folds and mountain folds are alternately formed. The height t of the corrugated structure (the difference in height between the recesses and protrusions of the corrugated structure when viewed from a direction parallel to the surface of the damper member) is preferably 0.2 mm to 3.0 mm, more preferably 0.5 mm to 2.5 mm, from the viewpoint of moldability and compliance. Similarly, the pitch L of the corrugated structure is preferably 0.5 mm to 5.0 mm, from the viewpoint of compliance. Note that the same cross-sectional shape does not necessarily have to be repeated. Also, the number of peaks in the corrugated structure is preferably 3 or more. In FIG. 5, the damper member 506 has a flat portion 5054 in the center of the annular corrugated structure 5053, but the corrugated structure 5053 may be provided all the way to the center of the annular structure without the flat portion 5054.

[0028] The deformation behavior of the damper member 506 caused by pressure fluctuations of the liquid in the liquid chamber will be described below.

[0029] When the pressure in the liquid chamber is reduced, the damper member 506 deforms in the Y direction in the figure to reduce the volume of the liquid chamber. On the other hand, when the pressure in the liquid chamber is increased, the damper member 506 deforms in the direction of the cover member 507, which is the -Y direction in the figure, to increase the volume of the liquid chamber (see FIG. 2). The cover member 507 is provided with a recess 517 so that the damper member 506 can deform in the -Y direction. That is, as shown in FIG. 25, the cover member has a cross-sectional shape that protrudes on the surface opposite to the damper member when viewed from a direction parallel to the surface of the damper member. Also, in order not to hinder the deformation of the damper member 506 in response to pressure fluctuations in the liquid chamber, the cover member 507 is provided with a communication port 511 for communicating the space between the cover member 507 and the damper member 505 with the atmosphere (see FIG. 24).

[0030] Various resin materials such as polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), polycarbonate (PC), polystyrene (PS), polyether ether ketone (PEEK), polyimide (PI), etc. can be used as the material for the damper member 506. Polyimide or polyether ether ketone is particularly preferable from the viewpoints of water resistance against liquids such as ink, robustness of the displacement of the annular wave structure against pressure, and moldability of the annular wave structure. EXAMPLES

[0031] The present invention will be described in more detail below with reference to examples thereof, but the present invention is not limited thereto.

[0032] In the embodiment of the present invention, the liquid supply unit shown in FIG. 2 was used to evaluate the damping performance of the damper members 506 having different wave structures 5053.

[0033] <Example 1> A damper member having the shape shown in FIG. 6(A) was used. The outer dimensions of the damper member 506 were length a=50 mm in the X direction and length b=40 mm in the Z direction. The dimensions of the annular wave structure 5053 were length c=17 mm in the X direction of the straight part and length d=8 mm in the Z direction. The cross-sectional shape of the wave structure was depth t=0.8 mm, pitch L=1.5 mm, and a wave shape with six peaks was provided. The material of the damper member was polyimide material 75RN (thickness 75 μm) manufactured by UBE Corporation, and the liquid supply unit 500 was manufactured.

[0034] <Example 2> Liquid supply unit 500 was produced in the same manner as in Example 1, except that a damper member having a shape shown in FIG. 6(B) was used and the dimensions of the straight portion of annular wave structure 5053 were set to d=4 mm.

[0035] <Example 3> Liquid supply unit 500 was produced in the same manner as in Example 1, except that a damper member having a shape shown in FIG. 6(C) was used and the dimensions of annular wave structure 5053 were set to straight portion c=8 mm.

[0036] <Example 4> Liquid supply unit 500 was produced in the same manner as in Example 1, except that the cross-sectional shape of the corrugated structure was set to a depth t of 0.5 mm.

[0037] <Example 5> Liquid supply unit 500 was produced in the same manner as in Example 1, except that the cross-sectional shape of the corrugated structure was set to a depth t of 2.5 mm.

[0038] <Example 6> A liquid supply unit 500 was produced in the same manner as in Example 1, except that a damper member having a shape shown in FIG. 6(D) was used and the cross-sectional shape of the corrugated portion was set to a pitch L of 3.0 mm.

[0039] <Example 7> A liquid supply unit 500 was produced in the same manner as in Example 1, except that a damper member having the shape shown in Figure 6(E) was used and a ring-shaped wave structure that does not have the straight portion d in Figure 6(A) was formed.

[0040] <Example 8> A damper member having the shape shown in Fig. 6(F) was used. A liquid supply unit 500 was produced in the same manner as in Example 1, except that a circular wave structure 5053 having a rounded triangular shape with three straight portions each 15 mm long was provided.

[0041] <Comparative Example 1> A liquid supply unit 500 was produced in the same manner as in Example 1, except that a damper member having the shape shown in Figure 7(A) was used, the annular wave structure 5053 was made circular with no straight sections, and the number of wave peaks was six.

[0042] <Comparative Example 2> A liquid supply unit 500 was produced in the same manner as in Example 1, except that a damper member having the shape shown in Figure 7(B) was used, the annular wave structure 5053 was made circular with no straight sections, and the number of wave peaks was set to 9.

[0043] <Evaluation of damper effect> The liquid supply units 500 produced in Examples 1 to 8 and Comparative Examples 1 and 2 were filled with liquid, and the damping effect was evaluated according to the following criteria. The results are shown in Table 1. Compliance was measured by the following method. First, the amount of liquid injected was gradually increased while measuring the internal pressure of the liquid chamber in the liquid supply unit 500. After the internal pressure (Pa) reached the level at which compliance was to be measured, an additional 0.1 ml of liquid was injected, and the injected volume (0.1 ml) was divided by the amount of change in internal pressure (Pa) to calculate the compliance (mm 3 / Pa) was calculated. Compliance was calculated at two points: internal pressure of 1000 Pa and 3000 Pa. The evaluations shown in Table 1 were determined based on the following criteria. A: The compliance is 0.3 mm when the internal pressure of the liquid chamber in the liquid supply unit 500 is 1000 Pa and 3000 Pa. 3 / Pa or more. B: Compliance is 0.2 mm when the internal pressure of the liquid chamber in the liquid supply unit 500 is 1000 Pa. 3 / Pa or more, but the compliance at 3000Pa is 0.2mm 3 / Pa or more 0.3mm 3 / Pa or less. C: Compliance is 0.2 mm when the internal pressure of the liquid chamber in the liquid supply unit is 1000 Pa. 3 / Pa or more, but the compliance at 3000Pa is 0.2mm 3 / Pa or less.

[0044] [Table 1]

[0045] In Examples 1 to 8 in which the damper member 506 having the annular corrugated structure 5053 with the straight portions 5052 was provided, high compliance was obtained at both the internal pressures of 1000 Pa and 3000 Pa. Among them, higher compliance was obtained in Examples 1 to 6 in which the annular corrugated structure 5053 was a rounded rectangle having four straight portions 5052. On the other hand, in Comparative Examples 1 and 2 in which the annular corrugated structure 5053 was a circle without straight portions 5052, compliance values ​​lower than those of Examples 1 to 8 were shown, particularly at the high pressure of 3000 Pa. [Explanation of symbols]

[0046] 10 Recording Device 100 Liquid ejection head 500 Liquid Supply Unit 504 Filter 505 Elastic Members 506 Damper material 507 Cover material 510 Flow path forming member

Claims

1. A liquid ejection head having an ejection port configured to eject a liquid, a recording element configured to eject the liquid from the ejection port, a flow path configured to supply the liquid to the ejection port, and a membrane member provided in the flow path, the membrane member has a wave-shaped structure in which a plurality of annular convex portions and annular concave portions are alternately formed, A liquid ejection head, characterized in that, when viewed from a direction perpendicular to the surface of the film member, the wave-shaped structure is a rounded rectangle having four straight portions and four curved portions.

2. A liquid ejection head having an ejection port configured to eject a liquid, a recording element configured to eject the liquid from the ejection port, a flow path configured to supply the liquid to the ejection port, and a deformable member provided in a liquid chamber of the flow path, the deformable member configured to deform so as to change the volume of the liquid chamber in response to pressure fluctuations of the liquid in the liquid chamber, the deforming member is configured to deform in response to the pressure fluctuation, and includes a plurality of alternating annular convex portions and annular concave portions; A liquid ejection head characterized in that, when viewed from a direction perpendicular to the surface on which the convex portions and the concave portions are formed, the ring shapes of the convex portions and the concave portions have rounded rectangles with four straight portions and four curved portions.

3. The liquid ejection head according to claim 1 , wherein the membrane member is sandwiched between a flow path forming member having the flow path and a cover member.

4. The liquid ejection head according to claim 3 , wherein the membrane member has a communication port for communicating a space between the membrane member and the cover member.

5. The liquid ejection head according to claim 3 , wherein the cover member has a cross-sectional shape that protrudes on a surface opposite to the membrane member when viewed in a direction parallel to the surface of the membrane member.

6. The liquid ejection head according to claim 3 , wherein the flow path forming member includes a filter for collecting foreign matter in the flow path, the filter being provided in a space surrounded by the flow path forming member and the membrane member.

7. 2. The liquid ejection head according to claim 1, wherein the film member is made of polyimide or polyether ether ketone.

8. 2. The liquid ejection head according to claim 1, wherein the height of the wave structure is 0.2 mm or more and 3.0 mm or less when viewed in a direction parallel to the surface of the film member.

9. the flow path forming member has a supply flow path for supplying liquid to the ejection port and a recovery flow path for recovering liquid from the ejection port, The liquid ejection head according to claim 1 , wherein the liquid in the liquid chamber is circulated.

10. The liquid ejection head according to claim 9 , wherein the flow path forming member further includes a bypass flow path that directly connects the supply flow path and the recovery flow path.

11. 2. The liquid ejection head according to claim 1, wherein the recording element is a piezoelectric element.

12. 2. The liquid ejection head according to claim 1, wherein the liquid is ink.

13. A membrane member provided in a liquid ejection device having a liquid ejection head for ejecting liquid and a tank for supplying the liquid, the membrane member being configured to deform in response to pressure fluctuations of the ink supplied from the tank to the liquid ejection head, A wave-shaped structure is formed in which a plurality of annular convex portions and annular concave portions are alternately formed, A membrane member characterized in that, when viewed in a direction perpendicular to the surface of the membrane member, the wave-shaped structure is a rounded rectangle having four straight portions and four curved portions.

14. The membrane member according to claim 13, which is formed from polyimide or polyetheretherketone.

15. The membrane member according to claim 13, wherein the height of the wave structure is 0.2 mm or more and 3.0 mm or less.

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