Liquid ejection head and liquid ejection apparatus

Abstract

The liquid ejection head includes a plurality of independent flow paths, a first common flow path, a second common flow path, a supply flow path, and a recovery flow path. Each of the independent flow paths has a pressurizing chamber, a first throttle portion between one end portion and the pressurizing chamber, and a second throttle portion between the other end portion and the pressurizing chamber. A first common flow path is connected to one end of each of the independent flow paths, and a second common flow path is connected to the other end of each of the independent flow paths. The supply flow path is connected to the first common flow path, and the recovery flow path is connected to the second common flow path. The combined flow path resistance of the second common flow path, the recovery flow path, and the first throttle section is greater than the combined flow path resistance of the first common flow path, the supply flow path, and the second throttle section.

Description

Technical Field

[0001] The present invention relates to a liquid ejection head and a liquid ejection apparatus including the liquid ejection head. Background Art

[0002] Conventionally, a liquid ejection apparatus including a liquid ejection head has been known (for example, see Patent Document 1). The liquid ejection head includes: a plurality of independent flow paths each having a nozzle and a pressure chamber formed with ejection holes for ejecting liquid; a first common liquid chamber connected to a first connection portion of each of the plurality of independent flow paths; and a second common liquid chamber connected to a second connection portion of each of the plurality of independent flow paths. In the liquid ejection head, the first common liquid chamber functions as a flow path of a supply system for supplying liquid to each of the plurality of independent flow paths, and the second common liquid chamber functions as a flow path of a recovery system for recovering liquid that has not been ejected from the ejection holes in each of the plurality of independent flow paths.

[0003] Prior Art Documents

[0004] Patent Documents

[0005] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2020-138373 Summary of the Invention

[0006] An object of the present invention is to provide a liquid ejection head and a liquid ejection apparatus including the liquid ejection head that can suppress the backflow of liquid from the flow path of the recovery system to the independent flow path during the ejection process of ejecting liquid from the ejection holes.

[0007] A liquid ejection head according to one embodiment of the present invention includes: a plurality of independent flow paths that are flow paths through which a liquid flows, each having one end portion, the other end portion, and ejection holes that are disposed between the one end portion and the other end portion and eject the liquid; a first common flow path that has a first opening and is connected to the one end portion of each of the independent flow paths; a second common flow path that has a second opening and is connected to the other end portion of each of the independent flow paths; a supply flow path that has a flow inlet through which the liquid flows in from the outside, is connected to the first opening of the first common flow path, and supplies the liquid that has flowed in through the flow inlet to the first common flow path through the first opening; and a recovery flow path that has a flow outlet through which the liquid flows out to the outside, is connected to the second opening of the second common flow path, and causes the liquid recovered from the second common flow path to flow to the flow outlet through the second opening. Each of the independent flow paths includes: a pressure chamber that is communicated with the ejection holes between the one end portion and the other end portion and is provided with a pressure applying portion that applies pressure; a first throttle portion that is disposed between the one end portion and the pressure chamber and has a flow path resistance greater than that of the pressure chamber; and a second throttle portion that is disposed between the other end portion and the pressure chamber and has a flow path resistance greater than that of the pressure chamber. The combined flow path resistance of the second common flow path, the recovery flow path, and the second throttle portion is greater than the combined flow path resistance of the first common flow path, the supply flow path, and the first throttle portion.

[0008] In addition, a liquid ejection head according to one aspect of the present invention includes: a plurality of independent flow paths that are flow paths through which a liquid flows, and each has one end portion, the other end portion, and an ejection hole that is disposed between the one end portion and the other end portion and ejects the liquid; a first common flow path that has a first opening and is connected to the one end portion of each of the independent flow paths; a second common flow path that has a second opening and is connected to the other end portion of each of the independent flow paths; a supply flow path that has a flow inlet through which the liquid flows in from the outside, is connected to the first opening of the first common flow path, and supplies the liquid flowing in from the flow inlet to the first common flow path through the first opening; and a recovery flow path that has a flow outlet through which the liquid flows out to the outside, is connected to the second opening of the second common flow path, and causes the liquid recovered from the second common flow path to flow to the flow outlet through the second opening. Each of the independent flow paths includes: a pressure chamber that is communicated with the ejection hole between the one end portion and the other end portion and is provided with a pressure applying portion for applying pressure; a first throttle portion that is provided between the one end portion and the pressure chamber and has a flow path resistance greater than that of the pressure chamber; and a second throttle portion that is provided between the other end portion and the pressure chamber and has a flow path resistance greater than that of the pressure chamber. The total area of the flow path cross-sectional areas of the second common flow path, the recovery flow path, and the second throttle portion is smaller than the total area of the flow path cross-sectional areas of the first common flow path, the supply flow path, and the first throttle portion.

[0009] A liquid ejection device according to another aspect of the present invention includes: the above-described liquid ejection head; and a circulation unit that is connected to the flow inlet and the flow outlet of the liquid ejection head and circulates the liquid through the liquid ejection head. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 is a side view of a printer that is a liquid ejection device according to an embodiment of the present invention.

[0011] Figure 2 is a top view of the printer.

[0012] Figure 3 is a schematic diagram showing the relationship between the liquid ejection head and the circulation unit in the printer.

[0013] Figure 4 is a top view of a first flow path member and a second flow path member included in a head body of the liquid ejection head.

[0014] Figure 5 is a cross-sectional view of a main part of the first flow path member.

[0015] Figure 6 is along Figure 4 a cross-sectional view of the second flow path member taken along line VI-VI.

[0016] Figure 7 is a cross-sectional view of a second flow path member along line VII-VII of Figure 4 .

[0017] Figure 8 is a cross-sectional view of a second flow path member along line VIII-VIII of Figure 4 .

[0018] Figure 9 is a top view of each plate included in the second flow path member.

[0019] Figure 10 is a graph showing the flow rate change during the ejection process of ejecting ink as a liquid from a liquid ejection head. DETAILED DESCRIPTION

[0020] Hereinafter, with reference to the accompanying drawings, a liquid ejection head and a liquid ejection device according to an embodiment of the present invention will be described. The liquid ejection device is a device including a liquid ejection head that ejects a liquid. Examples of the liquid ejection device include: a recording device that ejects ink as a liquid from a liquid ejection head; a device that ejects a liquid containing conductive particles from a liquid ejection head to print a wiring pattern of an electronic device; a device that ejects a liquid such as a chemical agent from a liquid ejection head toward a reaction vessel to produce a chemical. In the following embodiments, as a specific example of the liquid ejection device, an inkjet printer including a liquid ejection head that ejects ink as a liquid is exemplified. The inkjet printer is a recording device that prints an image such as characters and patterns on a workpiece such as a paper sheet, a resin sheet, a fabric such as a textile or a knitted fabric by an inkjet method.

[0021] [Overall Structure of Printer]

[0022] As shown in Figure 1 and Figure 2 , the printer 1 includes: a liquid ejection head 2 that ejects ink, a movable unit 7 that relatively moves a workpiece W with respect to the liquid ejection head 2, and a control unit 9. In the printer 1, the control unit 9 controls the liquid ejection head 2 based on print data that is data of an image, and ejects ink toward the workpiece W moved by the movable unit 7, so that ink droplets land on the workpiece W to perform printing or other recording on the workpiece W.

[0023] In the present embodiment, the printer 1 is a so-called line printer in which the liquid ejection head 2 is fixed to a head mounting frame 12 disposed in a head chamber 11. As other embodiments of the printer 1, a so-called serial printer can be exemplified in which the liquid ejection head 2 reciprocates in a direction intersecting the conveyance direction of the workpiece W and alternately performs an operation of ejecting ink from the liquid ejection head 2 and an operation of conveying the workpiece W.

[0024] In the printer 1, four flat head mounting frames 12 are arranged in the head chamber 11. A head group 2A including five liquid ejection heads 2 is mounted on each head mounting frame 12. The printer 1 has four head groups 2A and a total of 20 liquid ejection heads 2 are mounted.

[0025] The liquid ejection head 2 has an elongated strip shape in one direction. The liquid ejection head 2 is mounted on the head mounting frame 12 such that the ink ejection portion faces the printing surface of the workpiece W from above and its longitudinal direction is parallel to the direction orthogonal to the conveying direction of the workpiece W. In one head group 2A, three liquid ejection heads 2 are arranged along the direction orthogonal to the conveying direction of the workpiece W, and the other two liquid ejection heads 2 are respectively arranged between the three liquid ejection heads 2 at positions offset along the conveying direction. In other words, in one head group 2A, the liquid ejection heads 2 are arranged in a staggered manner. In one head group 2A, the liquid ejection heads 2 are arranged such that the ranges that can be printed by the respective liquid ejection heads 2 are connected in the width direction of the workpiece W, that is, the direction orthogonal to the conveying direction of the workpiece W. By such an arrangement of the respective liquid ejection heads 2 in the head group 2A, gapless printing can be performed in the width direction of the workpiece W based on the ink ejection from the respective liquid ejection heads 2.

[0026] The four head groups 2A are arranged along the conveying direction of the workpiece W. Each liquid ejection head 2 belonging to one head group 2A is supplied with ink of the same color, and four colors of ink can be printed by the four head groups 2A. The colors of the ink are, for example, magenta (M), yellow (Y), cyan (C), and black (BK).

[0027] The movable unit 7 relatively moves the workpiece W with respect to the liquid ejection head 2 mounted on the head mounting frame 12 in the head chamber 11. The movable unit 7 includes: a supply roller 71 and a supply adjustment roller 72 arranged on the upstream side in the conveying direction of the workpiece W with respect to the head chamber 11; a conveying roller 73 arranged in the head chamber 11; a first recovery adjustment roller 74, a second recovery adjustment roller 75, and a recovery roller 76 arranged on the downstream side in the conveying direction of the workpiece W with respect to the head chamber 11. The supply roller 71 is a roller that sends out the workpiece W. The supply adjustment roller 72 is a roller that guides the workpiece W sent out by the supply roller 71 into the head chamber 11. The conveying roller 73 is a roller that conveys the workpiece W guided into the head chamber 11 by the supply adjustment roller 72 so as to pass under the liquid ejection head 2. The first recovery adjustment roller 74 and the second recovery adjustment roller 75 are rollers that guide the workpiece W conveyed by the conveying roller 73 to the outside of the head chamber 11. The recovery roller 76 is a roller that recovers the workpiece W guided to the outside of the head chamber 11 by the first recovery adjustment roller 74 and the second recovery adjustment roller 75 by winding.

[0028] As Figure 1 and Figure 2As shown in the figure, the printer 1 of the present embodiment includes, in the conveying direction of the workpiece W: a coating unit 81 disposed between the supply adjustment roller 72 and the head chamber 11; a drying unit 82 disposed between the first recovery adjustment roller 74 and the second recovery adjustment roller 75; and an imaging unit 83 disposed between the second recovery adjustment roller 75 and the recovery roller 76.

[0029] The coating unit 81 coats the workpiece W before it is introduced into the head chamber 11 with a coating agent. As the coating agent, for example, when a member that is difficult for ink to penetrate is used as the workpiece W, a coating agent that forms an ink receiving layer on the workpiece W can be used so that the ink is easily fixed. In addition, as the coating agent, when a member that is easy for ink to penetrate is used as the workpiece W, a coating agent that forms an ink penetration suppression layer on the workpiece W can be used so that the penetration of the ink does not become excessive and hardly mixes with other ink that lands beside it.

[0030] The drying unit 82 dries the ink attached to the workpiece W before it is recovered by the recovery roller 76. As the drying method of the ink adopted by the drying unit 82, for example, a method of blowing warm air, a method of irradiating infrared rays, a method of bringing a heated roller into contact, etc. can be cited.

[0031] The imaging unit 83 images the workpiece W dried by the drying unit 82 and obtains imaging data for confirming the printing state of the ink on the workpiece W. The imaging data obtained by the imaging unit 83 is input to the control unit 9. The control unit 9 evaluates the printing state of the ink on the workpiece W based on the imaging data. Specifically, the control unit 9 evaluates whether there are pixels that are not printed because ink droplets are not ejected from the liquid ejection head 2, whether the landing positions of the ink droplets ejected from the liquid ejection head 2 are shifted, etc.

[0032] [Detailed Structure of the Liquid Ejection Head]

[0033] Next, with reference to Figures 3 to 9 The liquid ejection head 2 will be described in detail. It should be noted that in the following description, the outside of the liquid ejection head 2 is referred to as the outside. The liquid ejection head 2 includes: a head main body 21 in which a flow path for ejecting ink and the like is formed; and a housing 22 connected to the head main body 21 and accommodating a driver IC, a wiring board, etc. for controlling the ejection operation of the ink.

[0034] The head main body 21 has a flat plate shape that is longer in one direction. Hereinafter, regarding the directional relationship, in the length direction D1 of the head main body 21, one direction is referred to as the first direction D11, and the opposite direction of the first direction D11 is referred to as the second direction D12. In addition, in the width direction D2 orthogonal to the length direction D1 of the head main body 21, one direction is referred to as the third direction D21, and the opposite direction of the third direction D21 is referred to as the fourth direction D22. Further, the direction orthogonal to the length direction D1 and the width direction D2 in the head main body 21 is referred to as the thickness direction D3 of the head main body 21. In a state where the liquid ejection head 2 is mounted on the head mounting frame 12, the length direction D1 of the head main body 21 is parallel to the direction orthogonal to the conveyance direction of the workpiece W, the width direction D2 of the head main body 21 is parallel to the conveyance direction of the workpiece W, and the thickness direction D3 of the head main body 21 is parallel to the vertical direction perpendicular to the printing surface of the workpiece W.

[0035] As Figure 3 shown, the head main body 21 includes: a first flow path member 3 disposed in the lower portion of the head main body 21; a second flow path member 4 disposed in the upper portion of the head main body 21; and a piezoelectric actuator substrate 5 disposed between the first flow path member 3 and the second flow path member 4. The first flow path member 3 is a flat plate-shaped member in which a flow path for ejecting ink according to the drive of the piezoelectric actuator substrate 5 is formed. The second flow path member 4 is a flat plate-shaped member having an ink inlet 411 through which ink flows in from the outside and an ink outlet 421 through which ink flows out to the outside. The second flow path member 4 forms a flow path for supplying the ink flowing in from the ink inlet 411 to the first flow path member 3, and forms a flow path for allowing the ink recovered from the first flow path member 3 to flow to the ink outlet 421.

[0036] As Figure 3 shown, a circulation unit 6 is disposed outside the liquid ejection head 2. The circulation unit 6 is connected to the ink inlet 411 and the ink outlet 421 on the head main body 21. The circulation unit 6 circulates the ink through the head main body 21 by forming a flow of the ink from the ink outlet 421 toward the ink inlet 411.

[0037] The circulation unit 6 includes a supply storage unit 61, a recovery storage unit 62, a pump 63, an external supply flow path member 64, and an external recovery flow path member 65. The supply storage unit 61 stores the ink supplied to the ink inlet 411 of the head main body 21. The recovery storage unit 62 stores the ink flowing out from the ink outlet 421 of the head main body 21. The pump 63 sends the ink from the recovery storage unit 62 to the supply storage unit 61. The external supply flow path member 64 connects between the supply storage unit 61 and the ink inlet 411 of the head main body 21 and forms a flow path for allowing the ink stored in the supply storage unit 61 to flow to the ink inlet 411. The external recovery flow path member 65 connects between the recovery storage unit 62 and the ink outlet 421 of the head main body 21 and forms a flow path for allowing the ink flowing out from the ink outlet 421 to flow to the recovery storage unit 62.

[0038] As Figure 4 and Figure 5 shown, the first flow path member 3 disposed in the lower portion of the head main body 21 has a plurality of independent flow paths 31, a first common flow path 32, and a second common flow path 33. The first common flow path 32 is a flow path connected to one end portion 311 that serves as an inlet of each of the flow paths of the plurality of independent flow paths 31. The second common flow path 33 is a flow path connected to the other end portion 312 that serves as an outlet of each of the flow paths of the plurality of independent flow paths 31. In the present embodiment, the first flow path member 3 has a plurality of first common flow paths 32 connected to one end portion 311 of each of the plurality of independent flow paths 31, and has a plurality of second common flow paths 33 connected to the other end portion 312 of each of the plurality of independent flow paths 31. For example, the first flow path member 3 has four first common flow paths 32 and four second common flow paths 33.

[0039] The plurality of independent flow paths 31 each have one end portion 311 connected to the first common flow path 32 and the other end portion 312 connected to the second common flow path 33, and are flow paths through which ink flows from the one end portion 311 toward the other end portion 312. In each independent flow path 31, the one end portion 311 is the upstream end of the ink flow direction and is the inlet of the flow path, and the other end portion 312 is the downstream end of the ink flow direction and is the outlet of the flow path. The shape of the flow path cross section perpendicular to the ink flow direction in each independent flow path 31 is, for example, a rectangular shape. Each independent flow path 31 has: a pressure chamber 313 disposed on the upper surface 3A of the first flow path member 3 between the one end portion 311 and the other end portion 312; ejection holes 315 disposed on the lower surface 3B of the first flow path member 3 between the one end portion 311 and the other end portion 312; and a descender 314 connecting the pressure chamber 313 and the ejection holes 315.

[0040] The pressure chamber 313 opens upward on the upper surface 3A of the first flow path member 3 and communicates with the ejection holes 315 through the descender 314. On the upper surface 3A of the first flow path member 3, a piezoelectric actuator substrate 5 is joined so as to block the opening of the pressure chamber 313. Thus, a displacement element 51 assembled to the piezoelectric actuator substrate 5 is disposed above the pressure chamber 313. The displacement element 51 functions as a pressure applying portion for applying pressure to the pressure chamber 313. The descender 314 extends downward from the pressure chamber 313 to the ejection holes 315 along the thickness direction D3 of the first flow path member 3. The pressure chamber 313 is connected to the upper end of the descender 314, and the ejection holes 315 are connected to the lower end of the descender 314. The ejection holes 315 open downward on the lower surface 3B of the first flow path member 3, and eject the ink that has been pressurized by the pressure chamber 313 according to the drive of the displacement element 51 and passes through the inside of the descender 314.

[0041] The plurality of first common flow paths 32 are flow paths extending along the length direction D1 of the first flow path member 3. The flow direction of the ink in each first common flow path 32 is parallel to the length direction D1 of the first flow path member 3. Each first common flow path 32 functions as a flow path of a supply system for supplying ink to each independent flow path 31 by connecting to one end portion 311 of each of the plurality of independent flow paths 31. The shape of the flow path cross-section perpendicular to the flow direction of the ink in each first common flow path 32 is, for example, a rectangular shape. The flow path cross-sectional area representing the area of the flow path cross-section in each first common flow path 32 is the same within the entire range between the two end portions in the length direction D1. That is, the flow path cross-sectional area of each first common flow path 32 is uniform in the flow direction of the ink. The first common flow paths 32 are arranged and disposed in the width direction D2 of the first flow path member 3. Each first common flow path 32 has first openings 321 for receiving the ink supplied from the second flow path member 4 to the first flow path member 3 at the end portion in the first direction D11 and the end portion in the second direction D12 in the length direction D1, respectively. In each first common flow path 32, substantially the same amount of ink is supplied to the first opening 321 formed at the end portion in the first direction D11 and the first opening 321 formed at the end portion in the second direction D12. The ink supplied to the first openings 321 at the respective end portions of the first common flow path 32 flows toward the center in the length direction D1 of the first common flow path 32. The ink flowing in the first common flow path 32 is supplied to each independent flow path 31 whose one end portion 311 is connected to the first common flow path 32.

[0042] A first filter 311A is provided at the connection portion between the first common flow path 32 and one end portion 311 of each independent flow path 31. The first filter 311A allows the ink in the first common flow path 32 to pass through to each independent flow path 31 and restricts the passage of foreign substances and the like in the ink to each independent flow path 31.

[0043] In the first flow path member 3, the lower surface of the first common flow path 32 forms a first shock absorber 322. The surface of the first shock absorber 322 opposite to the surface facing the first common flow path 32 faces a first shock absorption chamber 323 into which air and other gases have entered. The volume of the first shock absorption chamber 323 changes according to the pressure applied from the first common flow path 32. The first shock absorber 322 can vibrate according to the volume change of the first shock absorption chamber 323. By the vibration attenuation of the first shock absorber 322, the pressure fluctuations generated in the first common flow path 32 can be attenuated. Therefore, by providing the first shock absorber 322 with respect to the first common flow path 32, pressure fluctuations such as resonance of the ink in the first common flow path 32 can be reduced.

[0044] The plurality of second common flow paths 33 are flow paths that extend along the length direction D1 at positions below the first common flow path 32 in the first flow path member 3. The flow direction of the ink in each second common flow path 33 is parallel to the length direction D1 of the first flow path member 3. Each second common flow path 33 functions as a flow path of a recovery system for recovering the ink that has not been ejected from the ejection holes 315 in each independent flow path 31 by being connected to the other end portions 312 of the plurality of independent flow paths 31 respectively. The shape of the flow path cross-section perpendicular to the flow direction of the ink in each second common flow path 33 is, for example, a rectangular shape. The flow path cross-sectional area representing the area of the flow path cross-section in each second common flow path 33 is the same throughout the range between the two end portions in the length direction D1. That is, the flow path cross-sectional area of each second common flow path 33 is uniform in the flow direction of the ink. The plurality of second common flow paths 33 are arranged and disposed in the width direction D2 of the first flow path member 3. Each second common flow path 33 has second openings 331 at the end portion in the first direction D11 and the end portion in the second direction D12 in the length direction D1, and the second openings 331 cause the ink that has not been ejected from the ejection holes 315 in each independent flow path 31 and has been recovered into the second common flow path 33 to flow toward the second flow path member 4. The ink recovered into the second common flow path 33 from each independent flow path 31 connected to the second common flow path 33 at the other end portion 312 flows toward the second openings 331 at the respective end portions in the second common flow path 33, and passes through the second openings 331 and is recovered into the second flow path member 4.

[0045] In the first flow path member 3, the lower surface of the second common flow path 33 serves as the second shock absorber 332. The surface of the second shock absorber 332 opposite to the surface facing the second common flow path 33 faces the second shock absorber chamber 333 into which gas such as air has entered. The volume of the second shock absorber chamber 333 changes according to the pressure applied from the second common flow path 33. The second shock absorber 332 can vibrate according to the volume change of the second shock absorber chamber 333. By the vibration attenuation of the second shock absorber 332, the pressure fluctuations generated in the second common flow path 33 can be attenuated. Therefore, by providing the second shock absorber 332 with respect to the second common flow path 33, the pressure fluctuations such as the resonance of the ink in the second common flow path 33 can be reduced.

[0046] When viewed from above in the thickness direction D3 of the first flow path member 3, the first common flow path 32 and the second common flow path 33 are overlapped and arranged. In a state where the plurality of independent flow paths 31 are connected to the first common flow path 32 at one end portion 311 and connected to the second common flow path 33 at the other end portion 312, they are arranged along the length direction D1 on both sides in the width direction D2 of the first common flow path 32 and the second common flow path 33.

[0047] In addition, each of the plurality of independent flow paths 31 has: a first throttle portion 316 disposed between one end portion 311 and the pressurizing chamber 313; and a second throttle portion 317 connected to the lower end of the lower extending portion 314 provided with the ejection hole 315 between the other end portion 312 and the pressurizing chamber 313.

[0048] The first throttle portion 316 is a flow path extending along the width direction D2 of the first flow path member 3 between one end portion 311 of the independent flow path 31 and the pressurizing chamber 313. The first throttle portions 316 communicate with the first common flow path 32 connected to one end portion 311 of the independent flow path 31 and the pressurizing chamber 313, respectively. The flow direction of the ink in the first throttle portion 316 is parallel to the width direction D2 of the first flow path member 3. The shape of the flow path cross section perpendicular to the flow direction of the ink in the first throttle portion 316 is, for example, a rectangular shape. The flow path cross-sectional area representing the area of the flow path cross section in the first throttle portion 316 is the same throughout the range between the two end portions. That is, the flow path cross-sectional area of the first throttle portion 316 is uniform in the flow direction of the ink. The flow path cross-sectional area of the first throttle portion 316 is smaller than the flow path cross-sectional area of the first common flow path 32, and smaller than the flow path cross-sectional areas of the pressurizing chamber 313 and the lower extending portion 314, respectively. Accordingly, the flow path resistance of the first throttle portion 316 is greater than the flow path resistance of the first common flow path 32, and greater than the flow path resistances of the pressurizing chamber 313 and the lower extending portion 314, respectively.

[0049] The second throttle portion 317 is a flow path extending along the width direction D2 of the first flow path member 3 between the other end portion 312 of the independent flow path 31 and the lower end of the lower extending portion 314. The second throttle portion 317 communicates with the second common flow path 33 connected to the other end portion 312 of the independent flow path 31, and passes through the lower extending portion 314 to communicate with the pressurizing chamber 313 and the ejection hole 315. The flow direction of the ink in the second throttle portion 317 is parallel to the width direction D2 of the first flow path member 3. The shape of the flow path cross section perpendicular to the flow direction of the ink in the second throttle portion 317 is, for example, a rectangular shape. The flow path cross-sectional area representing the area of the flow path cross section in the second throttle portion 317 is the same throughout the range between the two end portions. That is, the flow path cross-sectional area of the second throttle portion 317 is uniform in the flow direction of the ink. The flow path cross-sectional area of the second throttle portion 317 is smaller than the flow path cross-sectional area of the second common flow path 33, and smaller than the flow path cross-sectional areas of the pressurizing chamber 313 and the lower extending portion 314, respectively. Accordingly, the flow path resistance of the second throttle portion 317 is greater than the flow path resistance of the second common flow path 33, and greater than the flow path resistances of the pressurizing chamber 313 and the lower extending portion 314, respectively.

[0050] In the first flow path member 3 in which multiple independent flow paths 31, a first common flow path 32, and a second common flow path 33 are formed, the ink supplied from the second flow path member 4 to the first flow path member 3 flows into the first common flow path 32 through the first opening 321. The ink flowing into the first common flow path 32 flows into each independent flow path 31 through one end portion 311 that serves as a connection portion with the first common flow path 32. The ink flowing into each independent flow path 31 through the one end portion 311 flows into the pressure chamber 313 after passing through the first throttle portion 316. The ink flowing into the pressure chamber 313 flows in the downward extension portion 314, and a part of the ink is ejected from the ejection hole 315. The ink that is not ejected from the ejection hole 315 flows into the second common flow path 33 after passing through the second throttle portion 317 and then flows toward the second flow path member 4 through the second opening 331 and is recovered.

[0051] As Figure 5 shown, the first flow path member 3 has a laminated structure in which multiple plates are laminated in the thickness direction D3. In Figure 5 this example, the first flow path member 3 has 16 plates, namely, the first to sixteenth plates 3a to 3p, laminated in order from above.

[0052] One end portion 311 in each independent flow path 31 is defined by a hole formed in the fourth plate 3d, and the other end portion 312 in each independent flow path 31 is defined by a hole formed in the eleventh plate 3k. The pressure chamber 313 in each independent flow path 31 is defined by a hole formed in the topmost first plate 3a. The downward extension portion 314 in each independent flow path 31 is defined by holes formed in the second to fifteenth plates 3b to 3o in a manner that communicates with the hole in the first plate 3a that defines the pressure chamber 313. The ejection hole 315 in each independent flow path 31 is defined by a hole formed in the lowermost sixteenth plate 3p in a manner that communicates with the holes in the second to fifteenth plates 3b to 3o that define the downward extension portion 314. The first throttle portion 316 in each independent flow path 31 is defined by a hole formed in the third plate 3c in a manner that communicates with the hole in the fourth plate 3d that defines one end portion 311 and the hole in the first plate 3a that defines the pressure chamber 313. The second throttle portion 317 in each independent flow path 31 is defined by a hole formed in the fifteenth plate 3o in a manner that communicates with the hole in the eleventh plate 3k that defines the other end portion 312, the hole in the fifteenth plate 3o at the lower end that defines the downward extension portion 314, and the hole in the sixteenth plate 3p that defines the ejection hole 315.

[0053] Each first common flow path 32 is divided by holes formed in the fifth to eighth plates 3e to 3h in such a way as to communicate with the holes in the fourth plate 3d that divide one end portion 311 of each independent flow path 31. The first shock absorber 322 corresponding to each first common flow path 32 is formed by the ninth plate 3i facing the hole in the eighth plate 3h at the lower end that divides the first common flow path 32, and the first shock absorber chamber 323 corresponding to the first shock absorber 322 is divided by a groove formed in the tenth plate 3j.

[0054] Each second common flow path 33 is divided by holes formed in the eleventh to twelfth plates 3k to 3l in such a way as to communicate with the holes in the eleventh plate 3k that divide the other end portion 312 of each independent flow path 31. The second shock absorber 332 corresponding to each second common flow path 33 is formed by the thirteenth plate 3m facing the hole in the twelfth plate 3l at the lower end that divides the second common flow path 33, and the second shock absorber chamber 333 corresponding to the second shock absorber 332 is divided by a groove formed in the fourteenth plate 3n.

[0055] The second flow path member 4 disposed above the head main body 21 is joined to the region of the upper surface 3A of the first flow path member 3 where the piezoelectric actuator substrate 5 is not connected. That is, the second flow path member 4 is joined to the upper surface 3A of the first flow path member 3 so as to surround the piezoelectric actuator substrate 5. As Figure 4 and Figures 6 to 9 shown, the second flow path member 4 has a supply flow path 41 and a recovery flow path 42.

[0056] The supply flow path 41 is a flow path through which the ink supplied to each first common flow path 32 in the first flow path member 3 flows. The supply flow path 41 has an inlet 411 through which the ink flowing in the external supply flow path member 64 of the circulation unit 6 connected to the head main body 21 outside the liquid ejection head 2 flows in. The inlet 411 opens upward and to the outside in the end region in the second direction D12 in the length direction D1 of the second flow path member 4. The supply flow path 41 is connected to the first opening 321 of each first common flow path 32, and supplies the ink flowing in from the inlet 411 to each first common flow path 32 through the first opening 321.

[0057] The supply flow path 41 has an inflow connection flow path 412A connected to the inlet 411, a supply storage chamber 412 communicating with the inlet 411 through the inflow connection flow path 412A, a branch connection flow path 4131 connected to the supply storage chamber 412, and a supply branch flow path 413 communicating with the supply storage chamber 412 through the branch connection flow path 4131.

[0058] The inflow connection flow path 412A is a flow path that connects the flow inlet 411 and the supply storage chamber 412. The supply storage chamber 412 is disposed in a region on the D12 side of the central portion of the length direction D1 of the second flow path member 4 and extends along the length direction D1 of the second flow path member 4. The flow direction of the ink in the supply storage chamber 412 is parallel to the length direction D1 of the second flow path member 4. The shape of the flow path cross-section perpendicular to the flow direction of the ink in the supply storage chamber 412 is, for example, a rectangular shape. The flow path cross-sectional area representing the area of the flow path cross-section in the supply storage chamber 412 is the same throughout the range between the two end portions in the length direction D1. That is, the flow path cross-sectional area of the supply storage chamber 412 is uniform in the flow direction of the ink. The supply storage chamber 412 can store the ink flowing in from the flow inlet 411 and has a supply external opening 412B that faces upward and opens to the outside.

[0059] The supply external opening 412B of the supply storage chamber 412 is blocked by an elastic membrane 43 that can elastically deform. The volume of the supply storage chamber 412 changes according to the elastic deformation of the portion of the elastic membrane 43 facing the supply external opening 412B. The elastic membrane 43 can vibrate according to the elastic deformation that changes the volume of the supply storage chamber 412. By attenuating the vibration of the elastic membrane 43, the pressure fluctuation generated in the supply storage chamber 412 can be attenuated. Therefore, by blocking the supply external opening 412B of the supply storage chamber 412 with the elastic membrane 43, pressure fluctuations such as resonance of the ink in the supply storage chamber 412 can be reduced.

[0060] In addition, a second filter 412C is provided in the supply storage chamber 412. The second filter 412C allows the ink in the supply storage chamber 412 to pass through to the supply branch flow path 413 and restricts the passage of foreign substances and the like in the ink to the supply branch flow path 413.

[0061] The branch connection flow path 4131 is disposed in the central portion of the length direction D1 of the second flow path member 4 and is a flow path that connects the supply storage chamber 412 and the supply branch flow path 413.

[0062] The supply branch flow path 413 is a flow path that communicates with the supply storage chamber 412 through the branch connection flow path 4131 and is connected to the first common flow path 32 by connecting to the first opening 321 in the first flow path member 3. The supply branch flow path 413 has a first supply branch flow path 413A and a second supply branch flow path 413B.

[0063] The first supply branch flow path 413A is a flow path that is connected to the branch connection flow path 4131 at the central portion in the longitudinal direction D1 of the second flow path member 4 and extends along the longitudinal direction D1. The first supply branch flow path 413A includes a flow path that branches from the portion connected to the branch connection flow path 4131 and extends toward the first direction D11 and a flow path that extends toward the second direction D12. The flow direction of the ink in the first supply branch flow path 413A is parallel to the longitudinal direction D1 of the second flow path member 4. The shape of the flow path cross section perpendicular to the flow direction of the ink in the first supply branch flow path 413A is, for example, a rectangular shape. The flow path cross-sectional area representing the area of the flow path cross section in the first supply branch flow path 413A is the same within the entire range between the two end portions in the longitudinal direction D1. That is, the flow path cross-sectional area of the first supply branch flow path 413A is uniform in the flow direction of the ink.

[0064] The second supply branch flow path 413B is a flow path that is connected to the end portions in the first direction D11 and the second direction D12 in the longitudinal direction D1 of the first supply branch flow path 413A respectively and extends along the width direction D2, and is connected to the first openings 321 of the respective first common flow paths 32 in the first flow path member 3. The second supply branch flow path 413B includes a flow path that branches from the portion connected to the first supply branch flow path 413A and extends toward the third direction D21 in the width direction D2 and a flow path that extends toward the fourth direction D22 in the width direction D2. The flow direction of the ink in the second supply branch flow path 413B is parallel to the width direction D2 of the second flow path member 4. The shape of the flow path cross section perpendicular to the flow direction of the ink in the second supply branch flow path 413B is, for example, a rectangular shape. The flow path cross-sectional area representing the area of the flow path cross section in the second supply branch flow path 413B is the same within the entire range between the two end portions. That is, the flow path cross-sectional area of the second supply branch flow path 413B is uniform in the flow direction of the ink.

[0065] The recovery flow path 42 is a flow path through which the ink recovered from each of the second common flow paths 33 in the first flow path member 3 flows. The recovery flow path 42 has a flow outlet 421, and the ink flows out from the flow outlet 421 to the external recovery flow path member 65 of the circulation portion 6 connected to the head main body 21 outside the liquid ejection head 2. The flow outlet 421 opens upward and outward in the end region in the first direction D11 in the longitudinal direction D1 of the second flow path member 4. The recovery flow path 42 is connected to the second openings 331 of the respective second common flow paths 33, and the ink recovered from each of the second common flow paths 33 flows through the second openings 331 to the flow outlet 421.

[0066] The recovery flow path 42 has an outflow connection flow path 422A connected to the flow outlet 421, a recovery housing chamber 422 communicating with the flow outlet 421 through the outflow connection flow path 422A, and a recovery branch flow path 423 communicating with the recovery housing chamber 422.

[0067] The outflow connection flow path 422A is a flow path connecting the flow outlet 421 and the recovery storage chamber 422. The recovery storage chamber 422 is a flow path that is disposed in a region closer to the first direction D11 side than the central portion of the second flow path member 4 in the length direction D1 and extends along the length direction D1 of the second flow path member 4. The flow direction of the ink in the recovery storage chamber 422 is parallel to the length direction D1 of the second flow path member 4. The shape of the flow path cross section perpendicular to the flow direction of the ink in the recovery storage chamber 422 is, for example, a rectangular shape. The flow path cross-sectional area representing the area of the flow path cross section in the recovery storage chamber 422 is the same throughout the range between the two end portions in the length direction D1. That is, the flow path cross-sectional area of the recovery storage chamber 422 is uniform in the flow direction of the ink. The recovery storage chamber 422 can store the ink flowing out from the flow outlet 421 and has a recovery external opening 422B that faces upward and opens to the outside.

[0068] The recovery storage chamber 422 is arranged to be adjacent to the supply storage chamber 412 in the length direction D1 of the second flow path member 4. The recovery external opening 422B of the recovery storage chamber 422 is blocked by the elastic film 43 that is shared with the supply external opening 412B of the supply storage chamber 412. The volume of the recovery storage chamber 422 changes according to the elastic deformation of the portion of the elastic film 43 facing the recovery external opening 422B. The elastic film 43 can vibrate according to the elastic deformation that causes the volume of the recovery storage chamber 422 to change. By the vibration attenuation of the elastic film 43, the pressure fluctuation generated in the recovery storage chamber 422 can be attenuated. Therefore, since the recovery external opening 422B of the recovery storage chamber 422 is blocked by the elastic film 43, the pressure fluctuation such as the resonance of the ink in the recovery storage chamber 422 can be reduced.

[0069] It should be noted that the supply external opening 412B of the supply storage chamber 412 and the recovery external opening 422B of the recovery storage chamber 422 may also be blocked by independent elastic films respectively. That is, the supply external opening 412B of the supply storage chamber 412 may be blocked by the first elastic film, and on the other hand, the recovery external opening 422B of the recovery storage chamber 422 may be blocked by the second elastic film. When the supply external opening 412B of the supply storage chamber 412 and the recovery external opening 422B of the recovery storage chamber 422 are blocked by the shared elastic film 43, the elastic film 43 becomes a film in which the first elastic film blocking the supply external opening 412B and the second elastic film blocking the recovery external opening 422B are integrally formed.

[0070] The recovery branch flow path 423 is a flow path that communicates with the recovery storage chamber 422 and is connected to the second opening 331 in the first flow path member 3 to communicate with the second common flow path 33. The recovery branch flow path 423 has a first recovery branch flow path 423A and a second recovery branch flow path 423B.

[0071] The first recovery branch flow path 423A is a flow path that is connected to the recovery storage chamber 422 at the central portion in the length direction D1 of the second flow path member 4 and extends along the length direction D1. The first recovery branch flow path 423A includes a flow path that branches from the portion connected to the recovery storage chamber 422 and extends toward the first direction D11 and a flow path that extends toward the second direction D12. The first recovery branch flow path 423A is disposed at a position above the first supply branch flow path 413A in the second flow path member 4. When viewed from above in the thickness direction D3 of the second flow path member 4, the first supply branch flow path 413A and the first recovery branch flow path 423A are disposed such that at least a part of them overlaps with each other. The flow direction of the ink in the first recovery branch flow path 423A is parallel to the length direction D1 of the second flow path member 4. The shape of the flow path cross section perpendicular to the flow direction of the ink in the first recovery branch flow path 423A is, for example, a rectangular shape. The flow path cross-sectional area representing the area of the flow path cross section in the first recovery branch flow path 423A is the same throughout the entire range between the two end portions in the length direction D1. That is, the flow path cross-sectional area of the first recovery branch flow path 423A is uniform in the flow direction of the ink.

[0072] The second recovery branch flow path 423B is a flow path that is connected to the end portions of the first direction D11 and the second direction D12 in the length direction D1 of the first recovery branch flow path 423A, respectively, and extends along the width direction D2, and is connected to the second openings 331 of the respective second common flow paths 33 in the first flow path member 3. The second recovery branch flow path 423B includes a flow path that branches from the portion connected to the first recovery branch flow path 423A and extends toward the third direction D21 in the width direction D2 and a flow path that extends toward the fourth direction D22 in the width direction D2. The flow direction of the ink in the second recovery branch flow path 423B is parallel to the width direction D2 of the second flow path member 4. The shape of the flow path cross section perpendicular to the flow direction of the ink in the second recovery branch flow path 423B is, for example, a rectangular shape. The flow path cross-sectional area representing the area of the flow path cross section in the second recovery branch flow path 423B is the same throughout the entire range between the two end portions. That is, the flow path cross-sectional area of the second recovery branch flow path 423B is uniform in the flow direction of the ink.

[0073] In the second flow path member 4 in which the supply flow path 41 and the recovery flow path 42 are formed, the ink stored in the supply storage section 61 of the circulation section 6 connected to the head main body 21 passes through the external supply flow path member 64 and is supplied to the second flow path member 4. The ink supplied to the second flow path member 4 through the external supply flow path member 64 passes through the flow inlet 411 and the inflow connection flow path 412A and flows into the supply storage chamber 412. The ink flowing into the supply storage chamber 412 flows into the first supply branch flow path 413A through the branch connection flow path 4131. After flowing through the first supply branch flow path 413A, the ink flowing into the first supply branch flow path 413A flows into the second supply branch flow path 413B. The ink flowing into the second supply branch flow path 413B is supplied to each first common flow path 32 of the first flow path member 3 through the first opening 321 connected to the second supply branch flow path 413B. On the other hand, in the second flow path member 4, the ink recovered from each second common flow path 33 flows into the second recovery branch flow path 423B connected to the second opening 331 of each second common flow path 33 in the first flow path member 3. The ink flowing into the second recovery branch flow path 423B flows into the first recovery branch flow path 423A, and after flowing through the first recovery branch flow path 423A, it flows into the recovery storage chamber 422. The ink flowing into the recovery storage chamber 422 flows out from the flow outlet 421 through the outflow connection flow path 422A. The ink flowing out from the flow outlet 421 flows into the recovery storage section 62 through the external recovery flow path member 65 connected to the flow outlet 421. The ink stored by flowing into the recovery storage section 62 is sent from the recovery storage section 62 to the supply storage section 61 by the pump 63. Thus, the ink circulates through the head main body 21 including the first flow path member 3 and the second flow path member 4.

[0074] In addition, as Figure 6 shown, a housing space 44 for the piezoelectric actuator substrate 5 is provided on the lower surface of the second flow path member 4. The housing space 44 has through holes 441 penetrating to the upper surface of the second flow path member 4 at both ends in the third direction D21 and the fourth direction D22 in the width direction D2 of the second flow path member 4. A signal transmission section 442 such as an FPC (Flexible Printed Circuit) for transmitting a drive signal for driving the piezoelectric actuator substrate 5 passes through the through holes 441.

[0075] As Figures 6 to 9 shown, the second flow path member 4 has a laminated structure in which a plurality of plates are laminated in the thickness direction D3. In the Figure 6 example, seven plates, i.e., the first to seventh plates 4a to 4g, are laminated on the second flow path member 4 in order from above.

[0076] The inlet 411 in the supply flow path 41 and the outlet 421 in the recovery flow path 42 are defined by holes formed in the first and second plates 4a and 4b. The supply storage chamber 412 in the supply flow path 41 and the recovery storage chamber 422 in the recovery flow path 42 are defined by holes formed in the second and third plates 4b and 4c. An elastic film 43 that commonly blocks the supply external opening 412B of the supply storage chamber 412 and the recovery external opening 422B of the recovery storage chamber 422 is disposed between the first plate 4a and the second plate 4b. The inflow connection flow path 412A in the supply flow path 41 and the outflow connection flow path 422A in the recovery flow path 42 are defined by holes formed in the third plate 4c. The branch connection flow path 4131 in the supply flow path 41 is defined by a hole formed in the fourth plate 4d. The first supply branch flow path 413A in the supply flow path 41 is defined by a hole formed in the fifth plate 4e. The first recovery branch flow path 423A in the recovery flow path 42 is defined by a groove formed in the third plate 4c. The second supply branch flow path 413B in the supply flow path 41 is defined by holes formed in the fifth and sixth plates 4e and 4f. The second recovery branch flow path 423B in the recovery flow path 42 is defined by holes formed in the fourth to sixth plates 4d to 4f.

[0077] The accommodation space 44 for accommodating the piezoelectric actuator substrate 5 is defined by a hole formed in the seventh plate 4g. The through hole 441 through which the signal transmission portion 442 passes is defined by holes formed in the first to seventh plates 4a to 4g.

[0078] The piezoelectric actuator substrate 5 accommodated in the accommodation space 44 on the lower surface of the second flow path member 4 is joined to the upper surface 3A of the first flow path member 3. The piezoelectric actuator substrate 5 is disposed such that the displacement element 51 is located above each of the pressurization chambers 313 of the respective independent flow paths 31. The openings of the respective pressurization chambers 313 of the independent flow paths 31 are blocked by joining the piezoelectric actuator substrate 5 to the upper surface 3A of the first flow path member 3. A signal transmission portion 442 such as an FPC for supplying a signal to the displacement element 51 is connected to the piezoelectric actuator substrate 5.

[0079] As Figure 5 shown, the piezoelectric actuator substrate 5 has a laminated structure composed of two first piezoelectric ceramic layers 5A and second piezoelectric ceramic layers 5B that are piezoelectric bodies. Either the first piezoelectric ceramic layer 5A or the second piezoelectric ceramic layer 5B extends across a plurality of pressurization chambers 313. The first piezoelectric ceramic layer 5A and the second piezoelectric ceramic layer 5B are made of, for example, a lead zirconate titanate (PZT)-based, NaNbO 3 -based, BaTiO 3 -based, (BiNa)NbO 3 -based, BiNaNb 5 O 15 -based, or other ceramic materials having ferroelectricity.

[0080] The piezoelectric actuator substrate 5 has a common electrode 52 made of a metal material such as an Ag-Pd system and independent electrodes 53 made of a metal material such as an Au system. The independent electrodes 53 are respectively arranged at positions on the upper surface of the piezoelectric actuator substrate 5 that face the respective pressurizing chambers 313. A drive signal is supplied to the independent electrodes 53 from the control unit 9 through the signal transmission unit 442. The drive signal is supplied at a certain cycle in synchronization with the conveyance of the workpiece W. The common electrode 52 is formed over substantially the entire surface in the plane direction in the region between the first piezoelectric ceramic layer 5A and the second piezoelectric ceramic layer 5B. That is, the common electrode 52 extends so as to cover all the pressurizing chambers 313 in the region facing the piezoelectric actuator substrate 5. The common electrode 52 is connected to a surface electrode for the common electrode (not shown) through a through-conductor formed by penetrating the first piezoelectric ceramic layer 5A, and the surface electrode for the common electrode (not shown) is formed on the first piezoelectric ceramic layer 5A at a position avoiding the electrode group formed by the independent electrodes 53. In addition, the common electrode 52 is grounded through the surface electrode for the common electrode and is held at the ground potential. The surface electrode for the common electrode is connected to the control unit 9 directly or indirectly, similarly to the independent electrodes 53.

[0081] The portion of the first piezoelectric ceramic layer 5A sandwiched between the independent electrode 53 and the common electrode 52 is polarized in the thickness direction D3 and becomes a displacement element 51 having a unimorph structure. By the drive signal supplied to the independent electrode 53 under the control from the control unit 9 through a driver IC or the like, the displacement element 51 is driven (displaced). Although ink can be ejected from the ejection holes 315 by various drive signals, for example, by supplying a drive signal that is a pulse that becomes a low potential for a certain period with respect to a high potential to the independent electrode 53, ink can be ejected from the ejection holes 315.

[0082] Specifically, the independent electrode 53 is pre-set to a potential higher than that of the common electrode 52 (high potential). Whenever there is a ejection requirement, the independent electrode 53 is made to have the same potential as the common electrode 52 temporarily (low potential), and then it becomes a high potential again at a specified moment. Thus, at the moment when the independent electrode 53 becomes a low potential, the first piezoelectric ceramic layer 5A and the second piezoelectric ceramic layer 5B start to return to their original flat shape, and the volume of the pressure chamber 313 increases compared to the initial state. Thereby, a negative pressure is applied to the ink in the pressure chamber 313. Then, the ink in the pressure chamber 313 starts to vibrate with its natural vibration period. Specifically, initially, the volume of the pressure chamber 313 starts to increase and the negative pressure gradually decreases. Next, the volume of the pressure chamber 313 is at its maximum and the pressure becomes approximately zero. Then, the volume of the pressure chamber 313 starts to decrease and the pressure increases. Then, at the moment when the pressure becomes approximately maximum, the independent electrode 53 is made to have a high potential. Thus, the initially applied vibration overlaps with the subsequently applied vibration, and a greater pressure is applied to the ink. This pressure propagates in the lower extension portion 314 and the ink is ejected from the ejection hole 315.

[0083] That is, by supplying a drive signal of a pulse that becomes a low potential within a certain period based on the high potential to the independent electrode 53, the ink can be ejected from the ejection hole 315. When the pulse width is set to AL (Acoustic Length), which is half of the natural vibration period of the ink in the pressure chamber 313, in principle, the ejection speed and ejection amount of the ink can be maximized.

[0084] In the liquid ejection head 2 of the present embodiment, in each independent flow path 31, the first throttle portion 316 is a flow path connecting the first common flow path 32 and the pressure chamber 313, and the second throttle portion 317 is a flow path connecting the second common flow path 33 and the pressure chamber 313. Therefore, in order to ensure appropriate ejection characteristics of the ink from the ejection hole 315 in each independent flow path 31, it is required that the flow path resistance of the first throttle portion 316 be set with high precision to a value larger than the flow path resistances of the first common flow path 32, the pressure chamber 313, and the lower extension portion 314 respectively. Similarly, it is required that the flow path resistance of the second throttle portion 317 be set with high precision to a value larger than the flow path resistances of the second common flow path 33, the pressure chamber 313, and the lower extension portion 314 respectively.

[0085] When the flow path resistance of the first flow section 316 and the second flow section 317 is too small, the pressure wave generated in the pressurizing chamber 313 of one independent flow path 31 is transmitted to other independent flow paths 31 via the first common flow path 32 and the second common flow path 33, resulting in crosstalk where the ejection amount of the ink ejected from the ejection holes 315 of each independent flow path 31 becomes unstable. In such a case of crosstalk occurring, it is difficult to ensure appropriate ejection characteristics of the ink from the ejection holes 315 in each independent flow path 31. On the other hand, when the flow path resistance of the first flow section 316 and the second flow section 317 is too large, the supply amount of ink from the first common flow path 32 to each independent flow path 31 decreases, and the recovery amount of ink from each independent flow path 31 to the second common flow path 33 decreases. In this case, it is also difficult to ensure appropriate ejection characteristics of the ink from the ejection holes 315 in each independent flow path 31. In order to ensure appropriate ejection characteristics of the ink from the ejection holes 315 in each independent flow path 31, it is necessary to set the flow path resistance of each of the first flow section 316 and the second flow section 317 to a relatively large value with high precision.

[0086] Therefore, in the liquid ejection head 2 of the present embodiment, in each independent flow path 31, the flow path resistance of each of the first flow section 316 and the second flow section 317 is set so that the difference in their flow path resistances converges within a specified allowable range. Thus, compared with the case where there is a difference in the flow path resistances of the first flow section 316 and the second flow section 317 disposed on both sides across the pressurizing chamber 313 that exceeds the allowable range, the flow path resistance of each of the first flow section 316 and the second flow section 317 can be set to a relatively large value with high precision. Therefore, appropriate ejection characteristics of the ink from the ejection holes 315 in each independent flow path 31 can be ensured.

[0087] In the present embodiment, the flow path resistance of the second flow section 317 is preferably in a range of 15% or less smaller than the flow path resistance of the first flow section 316. That is, when the flow path resistance of the first flow section 316 is set as R1 and the flow path resistance of the second flow section 317 is set as R2, R1 and R2 are set so as to satisfy 0.85R1 ≤ R2 < R1. Thereby, while ensuring appropriate ejection characteristics of the ink from the ejection holes 315, the ink that is not ejected from the ejection holes 315 can easily flow through the second flow section 317 to the second common flow path 33. In this case, by making the flow path cross-sectional area of the second flow section 317 larger than that of the first flow section 316, the flow path resistance of the second flow section 317 can be made smaller than that of the first flow section 316.

[0088] In addition, when the ink is circulated via the head main body 21 by the driving of the pump 63 in the circulation unit 6, if the displacement element 51 disposed above the pressure chamber 313 of each independent flow path 31 is driven, a part of the ink supplied to the pressure chamber 313 through the first throttle portion 316 from the flow path of the supply system including the supply flow path 41 and the first common flow path 32 is ejected from the ejection hole 315. At this time, when the flow rate of the ink ejected from the ejection hole 315 of each independent flow path 31 becomes larger than a specified value, there is a case where the ink flows backward from the flow path of the recovery system including the second common flow path 33 and the recovery flow path 42 through the second throttle portion 317 to each independent flow path 31. Refer to Figure 10 the graph of the flow rate change shown in

[0089] When the pump 63 in the circulation unit 6 is driven, in the head main body 21, the ink circulates through the supply flow path 41 and the first common flow path 32 that are the flow paths of the supply system, each independent flow path 31, and the second common flow path 33 and the recovery flow path 42 that are the flow paths of the recovery system at a preset circulation flow rate QA. If the displacement element 51 is driven when the ink circulates at the circulation flow rate QA, the ink supplied to the pressure chamber 313 from the supply flow path 41 and the first common flow path 32 of the supply system through the first throttle portion 316 of each independent flow path 31 is ejected from the ejection hole 315 at an ejection flow rate based on the print data, and the ink that is not ejected from the ejection hole 315 flows through the second throttle portion 317 to the second common flow path 33 and the recovery flow path 42 of the recovery system and is recovered.

[0090] When the ejection of the ink from the ejection hole 315 starts according to the driving of the displacement element 51, the inflow rate of the ink flowing into the inlet 411 of the supply flow path 41 gradually increases from the circulation flow rate QA until it reaches the supply system saturation flow rate QS1 indicating the saturation flow rate of the ink flowing in the order of the supply flow path 41, the first common flow path 32, and the first throttle portion 316. The inflow rate of the ink flowing into the inlet 411 of the supply flow path 41 is maintained at the supply system saturation flow rate QS1 as a constant during the ejection process of the ink ejected from the ejection hole 315 at an ejection flow rate based on the print data. When the ejection of the ink from the ejection hole 315 ends, the inflow rate of the ink flowing into the inlet 411 of the supply flow path 41 gradually decreases from the supply system saturation flow rate QS1 until it returns to the circulation flow rate QA.

[0091] On the other hand, when the ejection of ink from the ejection holes 315 starts according to the drive of the displacement element 51, the outflow rate of the ink flowing out from the outflow port 421 of the recovery flow path 42 gradually decreases from the circulation flow rate QA until it reaches the recovery system saturation flow rate QS2 indicating the saturation flow rate of the ink flowing in the order of the second throttle portion 317, the second common flow path 33, and the recovery flow path 42. The outflow rate of the ink flowing out from the outflow port 421 of the recovery flow path 42 is kept fixed at the recovery system saturation flow rate QS2 during the ejection process of ejecting ink from the ejection holes 315 based on the print data. When the ejection of ink from the ejection holes 315 ends, the outflow rate of the ink flowing out from the outflow port 421 of the recovery flow path 42 gradually increases from the recovery system saturation flow rate QS2 until it returns to the circulation flow rate QA.

[0092] Here, in order to suppress the increase in the viscosity of the ink due to the evaporation of the volatile components in the ink, the circulation flow rate QA when the ink circulates through the head main body 21 is preset to be able to limit the retention of the ink near the ejection holes 315 that open to the outside in the head main body 21. In addition, the maximum ejection flow rate QB representing the maximum allowable value of the ejection flow rate when ejecting ink from the ejection holes 315 is preset in the head main body 21. The maximum ejection flow rate QB is set, for example, to a value greater than twice the circulation flow rate QA.

[0093] In addition, regarding the flow path resistance R of the supply flow path 41, the first common flow path 32, the first throttle portion 316 and the second throttle portion 317 in each independent flow path 31 of the supply system, and the second common flow path 33 and the recovery flow path 42 of the recovery system, when the flow path cross-sectional shape is a rectangular shape, the flow path resistance R is calculated according to the following formula (1).

[0094] [Formula 1]

[0095]

[0096] In formula (1), "a" represents the length of the long side of the rectangular flow path cross-section, "b" represents the length of the short side of the rectangular flow path cross-section, "L" represents the flow path length, which represents the length of the flow path along the ink flow direction, and "v" represents the viscosity of the ink. It should be noted that "X" in formula (1) is calculated according to the following formula (2).

[0097] [Formula 2]

[0098]

[0099] In formula (2), "a" and "b" are the same as in formula (1), "π" represents the pi, and "h" represents the attenuation constant.

[0100] As can be seen from Equation (1), the flow path resistance R of the supply flow path 41 of the supply system, the first common flow path 32, the first throttle portion 316 and the second throttle portion 317 in each independent flow path 31, and the second common flow path 33 and the recovery flow path 42 of the recovery system can be adjusted by the flow path cross-sectional area and the flow path length. In the present embodiment, the flow path resistance R of each flow path is adjusted by the flow path cross-sectional area of each flow path.

[0101] The supply system saturation flow rate QS1 during the ink ejection process in which ink is ejected from the ejection hole 315 at the maximum ejection flow rate QB is calculated according to the following Equation (3) using the circulation flow rate QA and the maximum ejection flow rate QB.

[0102] [Equation 3]

[0103]

[0104] In Equation (3), "RS1" represents the supply system combined flow path resistance, which represents the combined flow path resistance of the first common flow path 32, the supply flow path 41, and the first throttle portion 316, and "RS2" represents the recovery system combined flow path resistance, which represents the combined flow path resistance of the second common flow path 33, the recovery flow path 42, and the second throttle portion 317.

[0105] As can be seen from Equation (3), the supply system saturation flow rate QS1 is determined by the preset circulation flow rate QA, the maximum ejection flow rate QB, the supply system combined flow path resistance RS1, and the recovery system combined flow path resistance RS2.

[0106] The recovery system saturation flow rate QS2 during the ink ejection process in which ink is ejected from the ejection hole 315 at the maximum ejection flow rate QB is calculated based on the supply system saturation flow rate QS1 and the maximum ejection flow rate QB according to the following Equation (4).

[0107] [Equation 4]

[0108]

[0109] Since the recovery system saturation flow rate QS2 is based on the supply system saturation flow rate QS1 and the maximum ejection flow rate QB, like the supply system saturation flow rate QS1, it is determined by the preset circulation flow rate QA, the maximum ejection flow rate QB, the supply system combined flow path resistance RS1, and the recovery system combined flow path resistance RS2.

[0110] When the maximum ejection flow rate QB is set to a value greater than twice the recirculation flow rate QA, it is assumed that the combined flow path resistance RS1 of the supply system and the combined flow path resistance RS2 of the recovery system are the same. In this case, according to equations (3) and (4), the saturation flow rate QS2 of the recovery system is less than 0 (zero). For example, when the recirculation flow rate QA is set to 20 ml / minute and the maximum ejection flow rate QB is set to 100 ml / minute, and when the combined flow path resistance RS1 of the supply system and the combined flow path resistance RS2 of the recovery system are the same, according to equation (3), the saturation flow rate QS1 of the supply system is 70 ml / minute, and according to equation (4), the saturation flow rate QS2 of the recovery system is -30 ml / minute, and the saturation flow rate QS2 of the recovery system is less than 0 (zero). When the saturation flow rate QS2 of the recovery system is less than 0 (zero), during the ejection of ink from the ejection hole 315, the ink flows backward from the flow paths of the recovery system including the second common flow path 33 and the recovery flow path 42 through the second throttle portion 317 to each independent flow path 31.

[0111] When the ink flows backward from the flow paths of the recovery system including the second common flow path 33 and the recovery flow path 42 through the second throttle portion 317 to each independent flow path 31, since the ink flowing backward to each independent flow path 31 is ejected from the ejection hole 315, there is a possibility that the quality of the image formed on the workpiece W may be degraded due to the landing of the ejected ink. For example, when a first filter 311A and a second filter 412C are provided in the flow paths of the supply system including the first common flow path 32 and the supply flow path 41, and in contrast, no filter is provided in the flow paths of the recovery system, the ink containing foreign substances or the like flows backward from the flow paths of the recovery system through the second throttle portion 317 to each independent flow path 31. In this case, since the ink containing foreign substances or the like is ejected from the ejection hole 315, the quality of the image of the workpiece W is degraded due to the foreign substances or the like.

[0112] In order to suppress the situation where, during the ejection of ink from the ejection hole 315, the ink flows backward from the flow paths of the recovery system including the second common flow path 33 and the recovery flow path 42 through the second throttle portion 317 to each independent flow path 31, as shown in the following equation (5), during the ejection of ink from the ejection hole 315, it is necessary to make the saturation flow rate QS2 of the recovery system based on the saturation flow rate QS1 of the supply system and the maximum ejection flow rate QB not less than 0 (zero).

[0113] [Equation 5]

[0114]

[0115] Therefore, in the liquid ejection head 2 of the present embodiment, the recovery system combined flow path resistance RS2 representing the combined flow path resistance of the second common flow path 33, the recovery flow path 42, and the second throttle portion 317 is greater than the supply system combined flow path resistance RS1 representing the combined flow path resistance of the first common flow path 32, the supply flow path 41, and the first throttle portion 316. That is, the recovery system combined flow path resistance RS2 representing the combined flow path resistance of the recovery flow path 42, the second common flow path 33 connected to the recovery flow path 42, and the second throttle portion 317 connected to the second common flow path 33 is greater than the supply system combined flow path resistance RS1 representing the combined flow path resistance of the supply flow path 41, the first common flow path 32 connected to the supply flow path 41, and the first throttle portion 316 connected to the first common flow path 32. For example, when the circulation flow rate QA is set to 20 ml / minute and the maximum ejection flow rate QB is set to 100 ml / minute, it is assumed that the ratio of the supply system combined flow path resistance RS1 to the recovery system combined flow path resistance RS2 is 1:10. In this case, according to Equation (3), the supply system saturation flow rate QS1 is 110.9 ml / minute, and according to Equation (4), the recovery system saturation flow rate QS2 is 10.9 ml / minute, and the recovery system saturation flow rate QS2 satisfies Equation (5) and is not less than 0 (zero).

[0116] Compared with the case where the supply system combined flow path resistance RS1 and the recovery system combined flow path resistance RS2 are the same, by making the recovery system combined flow path resistance RS2 greater than the supply system combined flow path resistance RS1, regarding the outflow flow rate of the ink flowing out from the flow outlet 421 of the recovery flow path 42, the flow rate change between the circulation flow rate QA and the recovery system saturation flow rate QS2 can be reduced. Thereby, regarding the outflow flow rate of the ink from the flow outlet 421, it is possible to suppress the recovery system saturation flow rate QS2 from falling below 0 (zero), and thus it is possible to suppress the ink from flowing back from the flow path of the recovery system including the second common flow path 33 and the recovery flow path 42 through the second throttle portion 317 to the respective independent flow paths 31.

[0117] In order to reliably suppress the ink from flowing back from the flow path of the recovery system through the second throttle portion 317 to the respective independent flow paths 31, the recovery system combined flow path resistance RS2 may be set to a value greater than the supply system combined flow path resistance RS1 in such a manner as to satisfy the following Equation (6) using the circulation flow rate QA and the maximum ejection flow rate QB, which is derived from Equation (3) and Equation (5).

[0118] [Equation 6]

[0119]

[0120] As described above, it is clearly understood from Equation (1) that the flow path resistances R of the supply flow path 41 of the supply system, the first common flow path 32, the first throttle portion 316 and the second throttle portion 317 in each independent flow path 31, and the second common flow path 33 and the recovery flow path 42 of the recovery system can be adjusted by the flow path cross-sectional areas of the respective flow paths. Therefore, in the present embodiment, the total area of the flow path cross-sectional areas of the second common flow path 33, the recovery flow path 42, and the second throttle portion 317 is smaller than the total area of the flow path cross-sectional areas of the first common flow path 32, the supply flow path 41, and the first throttle portion 316. Thereby, the combined flow path resistance RS2 of the recovery system can be made greater than the combined flow path resistance RS1 of the supply system.

[0121] In the present embodiment, the flow path resistance R of the second common flow path 33 is greater than the flow path resistance R of the first common flow path 32. For example, by making the flow path cross-sectional area of the second common flow path 33 smaller than the flow path cross-sectional area of the first common flow path 32, the flow path resistance R of the second common flow path 33 can be made greater than the flow path resistance R of the first common flow path 32. Thereby, the combined flow path resistance RS2 of the recovery system and the combined flow path resistance RS1 of the supply system can be set such that the combined flow path resistance RS2 of the recovery system is greater than the combined flow path resistance RS1 of the supply system. Therefore, it is possible to more reliably suppress the reverse flow of the ink from the flow paths of the recovery system including the second common flow path 33 and the recovery flow path 42 through the second throttle portion 317 into each independent flow path 31.

[0122] In addition, in the present embodiment, the flow path resistance R of the recovery flow path 42 is greater than the flow path resistance R of the supply flow path 41. Specifically, the flow path resistance R of the first recovery branch flow path 423A in the recovery branch flow path 423 of the recovery flow path 42 is greater than the flow path resistance R of the first supply branch flow path 413A in the supply branch flow path 413 of the supply flow path 41. For example, by making the flow path cross-sectional area of the first recovery branch flow path 423A smaller than the flow path cross-sectional area of the first supply branch flow path 413A, the flow path resistance R of the first recovery branch flow path 423A can be made greater than the flow path resistance R of the first supply branch flow path 413A. Thereby, the combined flow path resistance RS2 of the recovery system and the combined flow path resistance RS1 of the supply system can be set such that the combined flow path resistance RS2 of the recovery system is greater than the combined flow path resistance RS1 of the supply system. Therefore, it is possible to more reliably suppress the reverse flow of the ink from the flow paths of the recovery system including the second common flow path 33 and the recovery flow path 42 through the second throttle portion 317 into each independent flow path 31.

[0123] In addition, in the present embodiment, the flow path resistance R of the second common flow path 33 is greater than the flow path resistance R of the first common flow path 32, and the flow path resistance R of the recovery flow path 42 is greater than the flow path resistance R of the supply flow path 41. Thus, the combined flow path resistance RS2 of the recovery system and the combined flow path resistance RS1 of the supply system can be set such that the combined flow path resistance RS2 of the recovery system is greater than the combined flow path resistance RS1 of the supply system. Therefore, it is possible to more reliably suppress ink from flowing back from the flow paths of the recovery system including the second common flow path 33 and the recovery flow path 42 through the second throttle portion 317 into the respective independent flow paths 31.

[0124] In addition, in the circulation unit 6 disposed outside the liquid ejection head 2, the flow path resistance of the external recovery flow path member 65 connected to the flow outlet 421 of the recovery flow path 42 may be set to a value greater than the flow path resistance of the external supply flow path member 64 connected to the flow inlet 411 of the supply flow path 41. In this case as well, it is possible to suppress ink from flowing back from the flow paths of the recovery system including the second common flow path 33 and the recovery flow path 42 through the second throttle portion 317 into the respective independent flow paths 31.

[0125] Regarding the inflow rate of the ink flowing into the flow inlet 411 of the supply flow path 41 and the outflow rate of the ink flowing out of the flow outlet 421 of the recovery flow path 42, the behavior of the flow rate change at the start of ink ejection from the ejection holes 315 is determined by the pressure loss P represented by the following formula (7) and the attenuation ratio d represented by the following formula (8).

[0126] [Formula 7]

[0127]

[0128] In formula (7), "R" represents the flow path resistance of each flow path of the supply system and the recovery system, and "U" represents the flow rate change of the inflow rate and the outflow rate.

[0129] [Formula 8]

[0130]

[0131] In formula (8), "C" represents the compliance of each of the supply storage chamber 412 and the recovery storage chamber 422, "R" represents the flow path resistance of each flow path of the supply system and the recovery system, and "M" represents the inertia of each of the supply storage chamber 412 and the recovery storage chamber 422.

[0132] The compliance C of each of the supply storage chamber 412 and the recovery storage chamber 422 represents the volume displacement per unit pressure corresponding to the elastic deformation of the elastic film 43 that blocks the supply external opening 412B of the supply storage chamber 412 and the recovery external opening 422B of the recovery storage chamber 422. When the volume of the ink in the flow path is V and the pressure applied to the ink in the flow path is p, the compliance C is defined by C = ΔV / Δp. When the density of the ink is ρ, the length of the flow path along the flow direction of the ink is L, and the cross-sectional area of the flow path is S, the inertia M of each of the supply storage chamber 412 and the recovery storage chamber 422 is defined by M = ρL / S.

[0133] In the present embodiment, since the recovery system combined flow path resistance RS2 is greater than the supply system combined flow path resistance RS1, according to Equation (8), the recovery storage chamber 422 of the recovery system is more likely to attenuate than the supply storage chamber 412 of the supply system. Therefore, when the ejection of the ink from the ejection hole 315 starts, the ink in the supply storage chamber 412 of the supply system undergoes pressure vibration more greatly than the recovery storage chamber 422 of the recovery system.

[0134] Therefore, in a state where the recovery system combined flow path resistance RS2 is greater than the supply system combined flow path resistance RS1, the compliance C of the supply storage chamber 412 is made greater than the compliance C of the recovery storage chamber 422 so that the attenuation ratio d in the supply storage chamber 412 is the same as the attenuation ratio d in the recovery storage chamber 422. In this case, the inertia M of the supply storage chamber 412 is made the same as the inertia M of the recovery storage chamber 422.

[0135] The compliance C of the supply storage chamber 412 can be adjusted, for example, by the opening area of the supply external opening 412B blocked by the elastic film 43 in the supply storage chamber 412. Similarly, the compliance C of the recovery storage chamber 422 can be adjusted, for example, by the opening area of the recovery external opening 422B blocked by the elastic film 43 in the recovery storage chamber 422. It should be noted that in the case where a first elastic film that blocks the supply external opening 412B of the supply storage chamber 412 and a second elastic film that blocks the recovery external opening 422B of the recovery storage chamber 422 are arranged as the elastic film 43, the compliance C of each of the supply storage chamber 412 and the recovery storage chamber 422 can also be adjusted according to the Young's modulus related to the elastic deformation of each of the first elastic film and the second elastic film and the thickness of the elastic film 43.

[0136] By making the compliance C of the supply storage chamber 412 greater than the compliance C of the recovery storage chamber 422 in such a way that the attenuation ratio d of each of the supply storage chamber 412 and the recovery storage chamber 422 is the same, when the ejection of the ink from the ejection hole 315 starts, the pressure vibration of the ink in each of the supply storage chamber 412 and the recovery storage chamber 422 can be made the same.

[0137] Reference numeral description:

[0138] 1 Printer (Liquid ejection device)

[0139] 2 Liquid ejection head

[0140] 3 First flow path member

[0141] 31 Independent flow path

[0142] 311 One end portion

[0143] 312 The other end portion

[0144] 313 Pressure chamber

[0145] 315 Ejection hole

[0146] 316 First throttle portion

[0147] 317 Second throttle portion

[0148] 32 First common flow path

[0149] 321 First opening

[0150] 33 Second common flow path

[0151] 331 Second opening

[0152] 4 Second flow path member

[0153] 41 Supply flow path

[0154] 411 Flow inlet

[0155] 412 Supply storage chamber

[0156] 42 Recovery flow path

[0157] 421 Flow outlet

[0158] 422 Recovery storage chamber

[0159] 43 Elastic membrane

[0160] 5 Piezoelectric actuator substrate

[0161] 51 Displacement element (Pressurizing portion)

[0162] 6 Circulation portion

[0163] 61 Supply storage portion

[0164] 62 Recovery storage portion

[0165] 63 Pump

[0166] 64 External supply flow path member

[0167] 65 External recycling flow path member.

Claims

1. A liquid ejection head, wherein, the liquid ejection head includes: a plurality of independent flow paths which are flow paths for liquid to flow, and each has one end portion, the other end portion, and ejection holes disposed between the one end portion and the other end portion for ejecting liquid; a first common flow path which has a first opening and is connected to the one end portion of each of the independent flow paths; a second common flow path which has a second opening and is connected to the other end portion of each of the independent flow paths; a supply flow path which has a flow inlet for liquid to flow in from the outside, is connected to the first opening of the first common flow path, and supplies the liquid flowing in from the flow inlet to the first common flow path through the first opening; and a recovery flow path which has a flow outlet for liquid to flow out to the outside, is connected to the second opening of the second common flow path, and allows the liquid recovered from the second common flow path to flow to the flow outlet through the second opening, each of the independent flow paths has: a pressure chamber which is provided to communicate with the ejection holes between the one end portion and the other end portion and is provided with a pressure applying portion for applying pressure; a first throttle portion which is provided between the one end portion and the pressure chamber and has a flow path resistance greater than that of the pressure chamber; and a second throttle portion which is provided between the other end portion and the pressure chamber and has a flow path resistance greater than that of the pressure chamber, the combined flow path resistance of the second common flow path, the recovery flow path, and the second throttle portion is greater than the combined flow path resistance of the first common flow path, the supply flow path, and the first throttle portion.

2. The liquid ejection head according to claim 1, wherein, the flow path resistances of the first throttle portion and the second throttle portion are each set such that the difference between their flow path resistances converges within a specified allowable range.

3. The liquid ejection head according to claim 2, wherein, the flow path resistance of the second throttle portion is within a range of being 15% or less smaller than the flow path resistance of the first throttle portion.

4. The liquid ejection head according to claim 1, wherein, the flow path resistance of the second common flow path is greater than the flow path resistance of the first common flow path.

5. The liquid ejection head according to claim 1, wherein, the flow path resistance of the recovery flow path is greater than the flow path resistance of the supply flow path.

6. The liquid ejection head according to claim 1, wherein, the flow path resistance of the second common flow path is greater than the flow path resistance of the first common flow path, and the flow path resistance of the recovery flow path is greater than the flow path resistance of the supply flow path.

7. The liquid ejection head according to claim 1, wherein, the supply flow path includes a supply storage chamber which communicates with the flow inlet, can store the liquid flowing in from the flow inlet, and has a supply external opening opening to the outside, the recovery flow path includes a recovery storage chamber which communicates with the flow outlet, can store the liquid flowing out from the flow outlet, and has a recovery external opening opening to the outside, the supply external opening of the supply storage chamber is blocked by a first elastic film capable of elastic deformation, The external opening of the recovery chamber is blocked by a second elastic film capable of elastic deformation. The compliance indicating the volume displacement per unit pressure corresponding to the elastic deformation of the first elastic film in the supply chamber is greater than the compliance indicating the volume displacement per unit pressure corresponding to the elastic deformation of the second elastic film in the recovery chamber.

8. The liquid ejection head according to claim 7, wherein, the first elastic film and the second elastic film are integrally formed.

9. A liquid ejection head, wherein, the liquid ejection head includes: a plurality of independent flow paths which are flow paths for liquid to flow, and each have one end, the other end, and ejection holes disposed between the one end and the other end for ejecting liquid; a first common flow path which has a first opening and is connected to the one end of each of the independent flow paths; a second common flow path which has a second opening and is connected to the other end of each of the independent flow paths; a supply flow path which has a flow inlet for liquid to flow in from the outside, is connected to the first opening of the first common flow path, and supplies the liquid flowing in from the flow inlet to the first common flow path through the first opening; and a recovery flow path which has a flow outlet for liquid to flow out to the outside, is connected to the second opening of the second common flow path, and allows the liquid recovered from the second common flow path to flow to the flow outlet through the second opening, each of the independent flow paths has: a pressure chamber which is provided to communicate with the ejection hole between the one end and the other end and is provided with a pressure applying portion for applying pressure; a first throttle portion which is provided between the one end and the pressure chamber and has a flow path resistance greater than that of the pressure chamber; and a second throttle portion which is provided between the other end and the pressure chamber and has a flow path resistance greater than that of the pressure chamber, the total area of the flow path cross-sectional areas of the second common flow path, the recovery flow path, and the second throttle portion is smaller than the total area of the flow path cross-sectional areas of the first common flow path, the supply flow path, and the first throttle portion.

10. A liquid ejection device, wherein, the liquid ejection device includes: the liquid ejection head according to any one of claims 1 to 9; and a circulation portion which is connected to the flow inlet and the flow outlet of the liquid ejection head and circulates liquid through the liquid ejection head.

11. The liquid ejection device according to claim 10, wherein, the circulation portion includes: a supply storage portion which stores the liquid supplied to the flow inlet of the liquid ejection head; a recovery storage portion which stores the liquid flowing out from the flow outlet of the liquid ejection head; a pump which sends the liquid from the recovery storage portion to the supply storage portion; an external supply flow path member which connects between the supply storage portion and the flow inlet and forms a flow path for the liquid stored in the supply storage portion to flow to the flow inlet; and an external recovery flow path member which connects between the recovery storage portion and the flow outlet and forms a flow path for the liquid flowing out from the flow outlet to flow to the recovery storage portion, The flow path resistance of the external recovery flow path member is greater than that of the external supply flow path member.

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