Liquid ejection head

Abstract

To provide a liquid discharge head that can enhance discharge stability.SOLUTION: A liquid discharge head according to an embodiment comprises a common liquid chamber, a common pressure chamber, an actuator, a substrate, a nozzle plate, and a damper. The common liquid chamber has an opening. The common pressure chamber is connected to a lower side of the common liquid chamber. The actuator has a plurality of pressure chambers connected to the common pressure chamber. The substrate is provided with the actuator and forms the common pressure chamber together with the actuator. The nozzle plate has a plurality of nozzles arranged in the plurality of pressure chambers respectively. The damper covers the opening of the common liquid chamber.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] An embodiment of the present invention relates to a liquid ejection head. [Background technology]

[0002] 2. Description of the Related Art Conventionally, there is known a liquid ejection head such as an inkjet head that applies a drive voltage to a piezoelectric element to generate distortion in the piezoelectric element, thereby depressurizing or pressurizing a pressure chamber and ejecting ink as a liquid from a nozzle.

[0003] The liquid supplied from the liquid inlet is supplied to the pressure chamber via a common liquid chamber. In a liquid ejection head configured in this manner, it is known to provide a damper using a flexible film to maintain a constant negative pressure in the pressure chamber.

[0004] However, the width of the pressure buffering area of ​​such a liquid ejection head is not sufficient to maintain a constant negative pressure, and the position of the pressure buffering area must be determined by the positions of the pressurized liquid chamber and the fluid resistance path, which limits the size of the damper. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2001-239668 Summary of the Invention [Problem to be solved by the invention]

[0006] The problem to be solved by the present invention is to provide a liquid ejection head that can improve ejection stability. [Means for solving the problem]

[0007] The liquid ejection head of the embodiment includes a common liquid chamber, a common pressure chamber, an actuator, a substrate, a nozzle plate, and a damper. The common liquid chamber has an opening. The common pressure chamber is connected to the lower side of the common liquid chamber. The actuator has a plurality of pressure chambers connected to the common pressure chamber. The substrate is provided with the actuator and forms the common pressure chamber together with the actuator. The nozzle plate has a plurality of nozzles respectively arranged in the plurality of pressure chambers. The damper covers the opening of the common liquid chamber. The strain area of ​​the damper is 3.18×10 -10 m^2 That's all. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a perspective view showing a configuration of a liquid ejection head according to an embodiment. [Figure 2] FIG. 2 is a perspective view showing the configuration of a head main body and a manifold unit of the liquid ejection head according to the embodiment. [Figure 3] FIG. 2 is a plan view showing the configuration of a head main body according to the embodiment. [Figure 4] FIG. 2 is a plan view showing the configuration of a manifold unit according to the embodiment. [Figure 5] 5 is a cross-sectional view showing the configuration of the head main body and the manifold unit according to the embodiment, taken along line VV in FIG. 4. [Figure 6] FIG. 2 is a cross-sectional view showing the configuration of a head main body and a manifold unit according to the embodiment. [Figure 7] FIG. 2 is a perspective view showing a part of the flow path configuration of the head main body and the manifold unit according to the embodiment. [Figure 8] FIG. 2 is a plan view showing a part of the flow path configuration of the head main body and the manifold unit according to the embodiment. [Figure 9] FIG. 3 is a side view showing a part of the flow path configuration of the head main body and the manifold unit according to the embodiment. [Figure 10] FIG. 3 is a side view showing a part of the flow path configuration of the head main body and the manifold unit according to the embodiment. [Figure 11]FIG. 4 is an explanatory diagram showing a change in pressure in a common pressure chamber. [Figure 12] FIG. 4 is an explanatory diagram showing a change in pressure in a common pressure chamber. [Figure 13] FIG. 4 is an explanatory diagram showing a change in pressure in a common pressure chamber. [Figure 14] FIG. 4 is an explanatory diagram showing a change in pressure in a common pressure chamber. [Figure 15] FIG. 4 is an explanatory diagram showing a change in pressure in a common pressure chamber. [Figure 16] FIG. 4 is an explanatory diagram showing a change in pressure in a common pressure chamber. [Figure 17] FIG. 10 is an explanatory diagram showing the relationship between the width of the damper and the strain area. [Figure 18] FIG. 10 is an explanatory diagram showing the relationship between the width of the damper and the strain area. [Figure 19] FIG. 1 is an explanatory diagram showing the configuration of a liquid ejection device according to an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] A liquid ejection head 1 according to an embodiment and a liquid ejection device 2 using the liquid ejection head 1 will be described below with reference to Figs. 1 to 19. Fig. 1 is a perspective view showing the configuration of the liquid ejection head 1 according to an embodiment. Fig. 2 is a perspective view showing the configuration of the head main body 11 and manifold unit 12 of the liquid ejection head 1, Fig. 3 is a plan view showing the configuration of the head main body 11 with the nozzle plate 114 omitted, and Fig. 4 is a plan view showing the configuration of the manifold unit 12.

[0010] FIG. 5 is a cross-sectional view of the head main body 11 and the manifold unit 12 taken along line VV in FIG. 4 , and FIG. 6 is a cross-sectional view of the head main body 11 and the manifold unit 12. FIG. 7 is a perspective view of a portion of the flow path configuration of the head main body 11 and the manifold unit 12. FIG. 8 is a plan view of a portion of the flow path configuration of the head main body 11 and the manifold unit 12. FIGS. 9 and 10 are side views of a portion of the flow path configuration of the head main body 11 and the manifold unit 12, shown from different directions. FIGS. 11 to 16 are explanatory diagrams showing changes in pressure in the common pressure chamber due to differences in the shape of the damper 127, and FIGS. 17 and 18 are explanatory diagrams showing the relationship between the shape of the damper 127 and the distortion area. FIG. 19 is an explanatory diagram showing the configuration of the liquid ejection device 2. Note that in each figure, the configuration is enlarged, reduced, or omitted as appropriate for ease of explanation.

[0011] The liquid ejection head 1 is an inkjet head provided in a liquid ejection device 2 such as the inkjet recording device shown in Fig. 19. The liquid ejection head 1 is provided in a head unit 2130 provided in the liquid ejection device 2, which includes a supply tank 2132 as a liquid storage section.

[0012] The liquid ejection head 1 is supplied with ink as a liquid stored in a supply tank 2132. The liquid ejection head 1 may be a non-circulation type head that does not circulate ink, or a circulation type head that circulates ink. In this embodiment, the liquid ejection head 1 will be described using an example of a non-circulation type head. The liquid ejection head 1 is also connected to a temperature adjustment device 2116 provided in the liquid ejection device 2, and is supplied with temperature adjustment liquid (temperature adjustment water) that controls the temperature of the ink.

[0013] 1 to 5, the liquid ejection head 1 includes a head main body 11, a manifold unit 12, a circuit board 13, and a cover 14. For example, the liquid ejection head 1 is a side-shooter type four-row integrated structure head that includes two sets of head main bodies 11, each having a pair of actuators 113.

[0014] The head body 11 ejects liquid. As shown in FIGS. 3, 5, and 6, the head body 11 includes a substrate 111, a frame 112, an actuator 113, and a nozzle plate 114. The head body 11 also includes a common pressure chamber 116. In this embodiment, an example will be described in which one head body 11 includes two actuators 113.

[0015] The substrate 111 is formed, for example, from a ceramic material in the shape of a rectangular plate. The substrate 111 is formed, for example, in the shape of a rectangle that is long in one direction. The substrate 111 has one or more supply ports 1111 and one or more discharge ports 1112. The substrate 111 is provided with a pair of actuators 113, and a wiring pattern for driving the actuators 113 is formed thereon. The supply port 1111 and the discharge port 1112 are through-holes that penetrate between both main surfaces of the substrate 111.

[0016] The supply port 1111 is provided singly, for example, at a position facing a first common pressure chamber 1161 (described later) of the common pressure chamber 116. The supply port 1111 is, for example, an elongated hole that is long in one direction along the longitudinal direction of the first common pressure chamber 1161.

[0017] For example, two exhaust ports 1112 are provided at positions facing one of two third common pressure chambers 1163 (described later) of the common pressure chamber 116. Also, for example, the exhaust ports 1112 are provided in the substrate 111 adjacent to one end of the pair of actuators 113 in the longitudinal direction.

[0018] The frame 112 is fixed to one main surface of the substrate 111 with an adhesive or the like. The frame 112 surrounds a supply port 1111, a plurality of discharge ports 1112, and an actuator 113, which are provided in the substrate 111.

[0019] For example, the frame 112 is formed in a rectangular frame shape, thereby forming an opening that is long in one direction along the longitudinal direction of the frame 112. In the opening of the frame 112, a pair of actuators 113, a supply port 1111, and two discharge ports 1112 are arranged.

[0020] A pair of actuators 113 is adhered to the mounting surface of the substrate 111. The pair of actuators 113 are arranged in two rows on the substrate 111 with a supply port 1111 between them. The actuators 113 are formed in the shape of a plate that is long in one direction. The actuators 113 are placed in an opening of the frame 112 and adhered to the main surface of the substrate 111. As a specific example, the actuators 113 are formed by adhering two rectangular plates of piezoelectric material that are long in one direction facing each other so that their polarization directions are opposite to each other. Here, the piezoelectric material is, for example, PZT (lead zirconate titanate). The actuators 113 are adhered to the mounting surface of the substrate 111 with, for example, a thermosetting epoxy adhesive.

[0021] The actuator 113 has, for example, a plurality of pressure chambers 1131 arranged at equal intervals in the longitudinal direction. A plurality of grooves are formed in the longitudinal direction of the actuator 113 on the main surface opposite the substrate 111 side of the actuator 113, and these grooves form the pressure chambers 1131. In other words, the actuator 113 has a plurality of walls arranged at equal intervals in the longitudinal direction and forming grooves therebetween. The plurality of walls 1133 form a plurality of pressure chambers 1131 between adjacent walls. The walls 1133 are piezoelectric bodies that change the volume of the pressure chambers 1131 when a drive voltage is applied.

[0022] The surface of the actuator 113 opposite to the substrate 111 is adhered to the nozzle plate 114. In addition, the actuator 113 has a wiring pattern formed thereon for driving the plurality of pressure chambers 1131.

[0023] The pressure chambers 1131 are pressure chambers for ejecting ink from nozzles 1141 when the liquid ejection head 1 performs operations such as printing. In this embodiment, an example has been described in which the actuator 113 has multiple pressure chambers 1131. However, for example, the actuator 113 may have air chambers arranged alternately with the multiple pressure chambers 1131. When an air chamber is provided adjacent to the pressure chamber 1131, nozzles 1141 are arranged in the nozzle plate 114 in a portion facing the pressure chamber 1131, and no nozzles 1141 are arranged in a portion facing the air chamber. In other words, ink is not ejected from the air chamber. For example, the air chamber is formed by blocking both ends of a groove in the actuator 113 with walls formed of a photosensitive resin. The air chamber is formed by blocking the groove in the actuator 113 with the substrate 111, the nozzle plate 114, and the walls at both ends.

[0024] The nozzle plate 114 is formed in a plate shape. The nozzle plate 114 is fixed with an adhesive or the like to the main surface of the frame body 112 opposite the substrate 111. The nozzle plate 114 has a plurality of nozzles 1141 formed in positions facing the plurality of pressure chambers 1131. In this embodiment, the nozzle plate 114 has two nozzle rows in which the plurality of nozzles 1141 are aligned in one direction.

[0025] The plurality of nozzles 1141 facing the plurality of pressure chambers 1131 are holes that eject ink when the liquid ejection head 1 performs an operation such as printing.

[0026] The common pressure chamber 116 communicates with the supply port 1111. The common pressure chamber 116 is provided around the pair of actuators 113. Specifically, the common pressure chamber 116 communicates with the primary side and secondary side of the multiple pressure chambers 1131 of each actuator 113. The common pressure chamber 116 also communicates with the discharge port 1112.

[0027] As a specific example, the common pressure chamber 116 has a first common pressure chamber 1161 that is long in one direction, two second common pressure chambers 1162 that are also long in one direction, and a third common pressure chamber 1163 that connects both ends of the first common pressure chamber 1161 to both ends of the two second common pressure chambers 1162. Furthermore, the common pressure chamber 116 communicates between the supply port 1111 and the primary sides of the multiple pressure chambers 1131 of the actuator 113 via the first common pressure chamber 1161, and communicates between the third common pressure chamber 1163 and the secondary sides of the multiple pressure chambers 1131 via the second common pressure chamber 1162.

[0028] The primary side of the pressure chamber 1131 is the upstream side of the pressure chamber 1131 in the direction of liquid flow, and in this embodiment, it is the first common pressure chamber 1161 side of the pressure chamber 1131. The secondary side of the pressure chamber 1131 is the downstream side of the pressure chamber 1131 in the direction of liquid flow, and in this embodiment, it is the second common pressure chamber 1162 side of the pressure chamber 1131.

[0029] The first common pressure chamber 1161 is formed between a pair of actuators 113. The first common pressure chamber 1161 constitutes an ink flow path from the supply port 1111 to the primary side openings of the multiple pressure chambers 1131 of each actuator 113. The first common pressure chamber 1161 also constitutes an ink flow path from the supply port 1111 to two third common pressure chambers 1163 on both end sides in the longitudinal direction of the first common pressure chamber 1161 (actuator 113).

[0030] The second common pressure chambers 1162 are formed between the respective actuators 113 and the frame 112. The second common pressure chambers 1162 form ink flow paths from the third common pressure chamber 1163 to the secondary side openings of the plurality of pressure chambers 1131.

[0031] The third common pressure chamber 1163 is adjacent to, for example, both ends in the longitudinal direction of the actuator 113. The third common pressure chamber 1163 communicates with the first common pressure chamber 1161 and the two second common pressure chambers 11162 at both ends in the longitudinal direction of the pair of actuators 113. The third common pressure chamber 1163 forms a flow path for part of the ink that leads from the first common pressure chamber 1161 to the second common pressure chamber 1162 without passing through the multiple pressure chambers 1131 of each actuator 113. The third common pressure chamber 1163 also forms a flow path for ink from the first common pressure chamber 1161 and the two second common pressure chambers 1162 to the outlet 1112.

[0032] 1, 2, and 4 to 6, the manifold unit 12 includes a manifold 121, a top plate 122, an ink supply pipe 123, an ink discharge pipe 124, a pair of temperature control pipes, a temperature control water supply pipe 125 and a temperature control water discharge pipe, and a damper 127. The numbers of the ink supply pipes 123, the ink discharge pipes 124, the temperature control water supply pipes 125, and the temperature control water discharge pipes can be set as appropriate.

[0033] The manifold 121 is formed in a plate or block shape. As shown in Figures 6 to 9, the manifold 121 includes a common liquid chamber 1211 that is continuous with the supply port 1111 of the substrate 111 and forms a liquid supply flow path, a discharge flow path 1212 that is continuous with the discharge port 1112 of the substrate 111 and forms a liquid discharge flow path, and a temperature adjustment flow path 1213 that forms a flow path for a temperature adjustment fluid. Figures 7 to 10 are views showing the configuration of the flow paths formed by the head main body 11 and the manifold unit 12.

[0034] One main surface of the manifold 121 is fixed to the main surface of the substrate 111. A top plate 122 is fixed to the main surface of the manifold 121 opposite to the main surface to which the substrate 111 is fixed. An ink supply pipe 123, an ink discharge pipe 124, a temperature-controlled water supply pipe 125, and a temperature-controlled water discharge pipe are fixed to the manifold 121 via the top plate 122, for example.

[0035] The common liquid chamber 1211 is a flow path formed by holes or grooves in the manifold 121. The common liquid chamber 1211 fluidly connects the ink supply pipe 123 and the supply port 1111 of the substrate 111.

[0036] 6 to 9, the common liquid chamber 1211 is a rectangular flow path extending along the longitudinal direction of the actuator 113 and the longitudinal direction of the supply port 1111. The supply port 1111 is continuous with the lower part of the common liquid chamber 1211, and a damper 127 is provided on the ceiling part 12111 above the common liquid chamber 1211.

[0037] For example, the longitudinal width of the common liquid chamber 1211 on the substrate 111 side is larger than the longitudinal width of the supply port 1111, and the longitudinal width of the ceiling portion 12111 is smaller than the longitudinal width on the substrate 111 side. Also, for example, the width of the upper ceiling portion 12111 of the common liquid chamber 1211 is larger than the width of other portions (on the substrate 111 side) in the short direction perpendicular to the longitudinal direction of the common liquid chamber 1211. For example, the manifold 121 is formed by assembling two parts that are separated into upper and lower parts, and the substrate 111 side is formed by the lower part, and the ceiling portion 12111 is formed by the upper part.

[0038] The discharge flow channel 1212 is a flow channel formed by holes or grooves in the manifold 121. The discharge flow channel 1212 fluidly connects, for example, the ink discharge tube 124 and the two discharge ports 1112 of the substrate 111.

[0039] The temperature adjustment flow path 1213 is a flow path formed by holes or grooves in the manifold 121. The temperature adjustment flow path 1213 fluidly connects the temperature adjustment water supply pipe 125 and the temperature adjustment water discharge pipe.

[0040] Both ends of the temperature adjustment flow path 1213 are openings connected to a temperature adjustment water supply pipe 125 and a temperature adjustment water discharge pipe provided on one main surface of the manifold 121. In addition, the temperature adjustment flow path 1213 is formed so as to be able to exchange heat with the substrate 111 fixed to the manifold 121.

[0041] The top plate 122 is provided on the surface of the manifold 121 opposite to the surface on which the substrate 111 is provided. The top plate 122 covers the manifold 121, thereby sealing the common liquid chamber 1211, the discharge flow path 1212, and the temperature adjustment flow path 1213.

[0042] The top plate 122 also has openings that connect the pipes 123, 124, and 125 and allow the pipes 123, 124, and 125 and the flow channels 1211, 1212, and 1213 to communicate with each other.

[0043] The ink supply pipe 123 is connected to a common liquid chamber 1211. The ink discharge pipe 124 is connected to a discharge flow path 1212. The temperature control water supply pipe 125 and the temperature control water discharge pipe are connected to the primary side and secondary side of the temperature control flow path 1213.

[0044] In this embodiment, an ink supply pipe 123 is disposed at one longitudinal end of the manifold 121, and an ink discharge pipe 124 is disposed at the other longitudinal end of the manifold 121. In addition, one of a temperature-controlled water supply pipe 125 and a temperature-controlled water discharge pipe is disposed at one longitudinal end of the manifold 121, and the other of the temperature-controlled water supply pipe 125 and the temperature-controlled water discharge pipe is disposed at the other longitudinal end of the manifold 121.

[0045] The damper 127 is formed in the shape of an elastically deformable thin film or sheet. The damper 127 covers the opening 12112 in the ceiling portion 12111 of the common liquid chamber 1211. Here, the opening 12112 in the ceiling portion 12111 is an opening formed on the surface of the manifold 121 on which the top plate 122 is provided. The damper 127 elastically deforms in response to pressure fluctuations in the common liquid chamber 1211. The damper 127 is fixed around the opening 12112 in the ceiling portion 12111 of the manifold 121. Furthermore, for example, the damper 127 is sandwiched between the manifold 121 and the top plate 122. The lower surface of the damper 127 faces the common liquid chamber 1211, and the upper surface faces the opening in the top plate 122.

[0046] As a specific example, the damper 127 is formed of a polyimide film. The damper 127 is formed in a rectangular shape that is long in the same direction as the longitudinal direction of the opening 12112 of the ceiling portion 12111 of the common liquid chamber 1211 that is long in one direction.

[0047] As a suitable example, the width of the damper 127 in the short-side direction is 4 mm or more. The width of the damper 127 in the short-side direction is a width that can be ensured when used in the head main body 11. Here, the width of the damper 127 in the short-side direction is the width of the opening 12112 of the ceiling portion 12111 of the common liquid chamber 1211 in the short-side direction. The thickness of the damper 127 is 25 μm or less. The lower limit of the thickness of the damper 127 is a thickness at which the pressure in the common liquid chamber 1211 does not cause plastic deformation of the damper 127, and is set depending on the characteristics of the damper 127. The damper 127 is formed, for example, using a polyimide film having a Young's modulus of 3.4 GPa.

[0048] The relationship between the width, thickness and Young's modulus in the short-side direction of the damper 127 and the function of the damper 127 will be described below with reference to FIGS.

[0049] 11 to 14 show the fluctuations in pressure when the width in the short direction of the damper 127 is changed. In Figures 11 to 14, pressure is detected and graphed at the longitudinal ends of the common pressure chamber 116, the longitudinal center of the common pressure chamber 116, and at the inlet of the common liquid chamber 1211, which serves as the inlet of the ink supply path. In addition, Figure 11 shows an example in which the short-side width W of the damper 127 (the short-side width of the opening 12112 of the ceiling portion 12111 of the common liquid chamber 1211) is 1.2 mm, Figure 12 shows an example in which the short-side width W of the damper 127 (the short-side width of the opening 12112 of the ceiling portion 12111 of the common liquid chamber 1211) is 2.0 mm, Figure 15 shows an example in which the short-side width W of the damper 127 (the short-side width of the opening 12112 of the ceiling portion 12111 of the common liquid chamber 1211) is 3.0 mm, and Figure 16 shows an example in which the short-side width W of the damper 127 (the short-side width of the opening 12112 of the ceiling portion 12111 of the common liquid chamber 1211) is 4.0 mm.

[0050] In all of the examples shown in Figures 11 to 14, the liquid ejection head 1 was driven under the same conditions, and the damper 127 was formed using a polyimide film with a thickness t of 25 μm and a Young's modulus E of 3.4 GPa.

[0051] As shown in FIG. 11, when the width W of the damper 127 in the short-side direction was 1.2 mm, the pressure fluctuations at each position were large. As shown in FIGS. 11 to 14, as the width W of the damper 127 in the short-side direction increased, the pressure fluctuations at each position decreased. Furthermore, when the width W of the damper 127 in the short-side direction was 4 mm, there was almost no pressure fluctuation at each position. As is clear from these pressure fluctuation results, as the width W of the damper 127 in the short-side direction increased, both the peak pressure value and the number of fluctuations per hour decreased. As is clear from these results, providing the damper 127 has the effect of suppressing pressure fluctuations. Furthermore, by setting the width W of the damper 127 in the short-side direction to 4 mm or more, pressure fluctuations can be suitably suppressed.

[0052] 15 and 16 show the relationship of pressure fluctuation when the thickness t of the damper 127 is set to 50 μm and 25 μm. In the example shown in Figures 15 and 16, the damper 127 has a width W in the short side direction of 4.0 mm and is formed from a polyimide film with a Young's modulus of 3.4 GPa. Figures 15 and 16 also graph the pressure at the end of the common pressure chamber 116, the center of the common pressure chamber 116, and the inlet of the common liquid chamber 1211 which serves as the inlet of the ink supply path.

[0053] As shown in Figures 15 and 16, the pressure fluctuations when a damper 127 with a thickness of 50 µm was used were larger than the pressure fluctuations when a damper 127 with a thickness of 25 µm was used. In particular, when the thickness t of the damper 127 was set to 25 µm, almost no pressure fluctuations were observed. As is clear from these results, providing the damper 127 has the effect of suppressing pressure fluctuations. Furthermore, by setting the thickness t of the damper 127 to 25 µm or less, pressure fluctuations can be suitably suppressed.

[0054] 17 and 18 are graphs showing the relationship between the strain area ds and the width in the short direction of the damper 127 when the Young's modulus E of the polyimide film from which the damper 127 is formed is 9.1 GPa and 3.4 GPa, respectively, and the thickness t of the damper 127 is 10 μm, 20 μm, 30 μm, 40 μm, and 50 μm.

[0055] Here, the strain area ds is calculated from the following formula based on the thickness t (m) of the damper 127 and the width W (m) of the damper 127 in the lateral direction (short side).

[0056]

number

[0057] Here, the coefficient k varies depending on the Young's modulus E of the damper 127. For example, when the Young's modulus E of the damper 127 is 9.1 GPa, the coefficient k is 2.066×10 -12 When the Young's modulus E of the damper 127 is 3.4 GPa, the coefficient k is 5.530 × 10 -12 is.

[0058] As shown in Figures 17 and 18, at each thickness t, the damper 127 made of a polyimide film with a Young's modulus E of 3.4 GPa has a larger strain area ds than the damper 127 made of a polyimide film with a Young's modulus E of 9.1 GPa.

[0059] For example, in order to increase the strain area ds, it is preferable that the damper 127 be formed of a polyimide film having a Young's modulus E of 3.4 GPa. For this reason, a suitable example of the damper 127 is one in which the width W in the short side direction of the damper 127 is 4 mm or more, the thickness t of the damper 127 is 25 μm or less, and the Young's modulus E of the polyimide film forming the damper 127 is 3.4 GPa.

[0060] The strain area ds is, for example, 3.18 × 10 -10m^2 However, if the strain area ds can be set to a desired value, the thickness t, width W in the short side direction, and Young's modulus E of the damper 127 can be set appropriately.

[0061] One end of circuit board 13 is connected to the wiring pattern of actuator 113 via the wiring pattern of substrate 111. Circuit board 13 includes, for example, a wiring film, a driver IC mounted on the wiring film, and a printed wiring board mounted on the wiring film.

[0062] The circuit board 13 drives the actuator by applying a drive voltage to the wiring pattern of the actuator using a driver IC, thereby increasing or decreasing the volume of the pressure chamber 1131 and causing droplets to be ejected from the nozzle 1141.

[0063] For example, a plurality of wiring films are provided. The wiring film is, for example, a COF (Chip on Film) on which a driver IC is mounted. The driver IC is electrically connected to the wiring pattern formed in the pressure chamber 1131 via the wiring film. The printed wiring board is a PWA (Printing Wiring Assembly) on which various electronic components and connectors are mounted.

[0064] The cover 14 covers or houses a part of the head body 11 , a part of the manifold unit 12 and the circuit board 13 .

[0065] The liquid ejection head 1 configured in this manner is provided in an inkjet recording apparatus, which is an example of the liquid ejection device 2 shown in FIG. 19. Hereinafter, the liquid ejection device 2 will be described as the inkjet recording apparatus 2. The liquid ejection head 1 is connected to a supply tank 2132 serving as a liquid storage unit provided in the inkjet recording apparatus 2. The liquid ejection head 1 is either a circulation type head that circulates ink between the supply tank 2132 and the liquid ejection head 1, or a non-circulation type head that is supplied with ink from the supply tank 2132 and discharges ink to a maintenance device 2117 during maintenance. The liquid ejection head 1 is disposed in a position where the nozzles 1141 of the nozzle plate 114 of the head main body 11 face downward.

[0066] An inkjet recording apparatus 2 having a liquid ejection head 1 will be described below with reference to Fig. 19. The inkjet recording apparatus 2 includes a housing 2111, a medium supply unit 2112, an image forming unit 2113, a medium discharge unit 2114, a conveying device 2115 which is a support device, a temperature adjustment device 2116, a maintenance device 2117, and a control unit 2118.

[0067] The inkjet recording device 2 is an inkjet printer that performs an image formation process on paper P by ejecting a liquid such as ink while transporting the paper P as a recording medium, which is the object of ejection, along a predetermined transport path 2001 that runs from a medium supply section 2112 through an image forming section 2113 to a medium ejection section 2114.

[0068] The medium supply unit 2112 includes a plurality of paper feed cassettes 21121. The image forming unit 2113 includes a support unit 2120 that supports paper, and a plurality of head units 2130 that are arranged above and facing the support unit 2120. The medium discharge unit 2114 includes a paper discharge tray 21141.

[0069] The support section 2120 includes a conveyor belt 21201 that is looped in a predetermined area where image formation is performed, a support plate 21202 that supports the conveyor belt 21201 from the back side, and a plurality of belt rollers 21203 that are provided on the back side of the conveyor belt 21201.

[0070] The head unit 2130 includes liquid ejection heads 1 which are multiple inkjet heads, multiple supply tanks 2132 as liquid tanks mounted on each liquid ejection head 1, a pump 2134 which supplies ink, and a connection flow path 2135 which connects the liquid ejection heads 1 and the supply tanks 2132.

[0071] In this embodiment, the liquid ejection heads 1 are provided with four colors of liquid ejection heads 1 (cyan, magenta, yellow, and black), and four color supply tanks 2132 that respectively store ink of each color. The supply tanks 2132 are connected to the liquid ejection heads 1 by connection flow paths 2135.

[0072] The pump 2134 is a liquid-transfer pump that is configured, for example, as a piezoelectric pump. The pump 2134 is connected to the control unit 2118, and is controlled by the control unit 2118.

[0073] The connection flow path 2135 includes a supply flow path connected to the ink supply pipe 123 of the liquid ejection head 1. The connection flow path 2135 also includes a recovery flow path connected to the ink discharge pipe 124 of the liquid ejection head 1. For example, since the liquid ejection head 1 is of a non-circulation type, the recovery circuit is connected to a maintenance device 2117. Note that, for example, if the liquid ejection head 1 is of a circulation type, the recovery flow path is connected to a supply tank 2132.

[0074] The transport device 2115 transports the paper P along a transport path 2001 that runs from a paper feed cassette 21121 in the medium supply unit 2112, through the image forming unit 2113, to a paper discharge tray 21141 in the medium discharge unit 2114. The transport device 2115 includes a plurality of guide plate pairs 21211-21218 and a plurality of transport rollers 21221-21228 that are arranged along the transport path 2001. The transport device 2115 supports the paper P so that it can move relative to the liquid ejection head 1.

[0075] The temperature adjustment device 2116 includes a temperature adjustment water tank 21161, a temperature adjustment circuit 21162 such as piping or tubes for supplying the temperature adjustment water, a pump for supplying the temperature adjustment water, and a temperature adjuster for adjusting the temperature of the temperature adjustment water. The temperature adjustment device 2116 supplies the temperature adjustment water in the temperature adjustment water tank 21161, which has been adjusted to a predetermined temperature by the temperature adjuster, to the temperature adjustment water supply pipe 125 via the temperature adjustment circuit 21162 by pumping water. The temperature adjustment device 2116 also recovers water that has passed through the manifold 121 and been discharged from the temperature adjustment water discharge pipe into the temperature adjustment water tank 21161 via the temperature adjustment circuit 21162. The temperature adjuster is, for example, a heater or a cooler.

[0076] The maintenance device 2117, for example, during maintenance, sucks and recovers ink remaining on the outer surface of the nozzle plate 114. Furthermore, if the liquid ejection head 1 is of a non-circulation type, the maintenance device 2117 recovers ink from inside the head body 11 through the nozzles 1141 during maintenance. Such a maintenance device 2117 has a tray, tank, or the like for storing the recovered ink.

[0077] The control unit 2118 includes a CPU 21181 as an example of a processor, a ROM (Read Only Memory) for storing various programs, a RAM (Random Access Memory) for temporarily storing various variable data and image data, and other memories, and an interface unit for inputting data from the outside and outputting data to the outside.

[0078] Next, we will explain the flow of ink as a liquid in the thus configured liquid ejection head 1. First, when ink as a liquid is supplied to the ink supply pipe 123, the ink flows through the common liquid chamber 1211 of the manifold 121. Then, the ink moves from the supply port 1111 of the substrate 111 that faces the common liquid chamber 1211 to the first common pressure chamber 1161.

[0079] A portion of the ink that has moved to the first common pressure chamber 1161 moves to the plurality of pressure chambers 1131, as shown by the arrows in FIG. 3. A portion of the ink that has moved to the first common pressure chamber 1161 moves to the third common pressure chamber 1163, as shown by the arrows in FIG. 3. The ink that has moved to the third common pressure chamber 1163 moves to the second common pressure chamber 1162. The ink that has moved to the second common pressure chamber 1162 moves to the plurality of pressure chambers 1131. That is, in this embodiment, ink is supplied to the plurality of pressure chambers 1131 from both the first common pressure chamber 1161 and the second common pressure chamber 1162. When the pressure chamber 1131 is driven, the ink in the driven pressure chamber 1131 is ejected from the nozzle 1141.

[0080] In this embodiment, the liquid ejection head 1 is of a non-circulation type, and therefore the ink in the second common pressure chamber 1162 moves to the multiple pressure chambers 1131. Then, when the secondary side of the ink discharge pipe 124 is opened during maintenance, ink filling, or the like, the ink in the second common pressure chamber 1162 moves to the ink discharge pipe 124 through the third common pressure chamber 1163, the discharge port 1112 of the substrate 111, and the discharge flow path 1212 of the manifold 121.

[0081] Furthermore, when the pressure chamber 1131 is driven during maintenance or ink filling, the ink in the pressure chamber 1131 is ejected from the nozzle 1141 together with air bubbles accumulated in, for example, the first common pressure chamber 1161, the second common pressure chamber 1162, and the third common pressure chamber 1163.

[0082] Furthermore, since the liquid ejection head 1 is oriented such that the head main body 11 is located downward and the manifold unit 12 is located upward in the direction of gravity, if there are any air bubbles in the common liquid chamber 1211, the air bubbles in the common liquid chamber 1211 will be located directly below the damper 127. Therefore, during maintenance or ink filling, the ink and air bubbles in the common liquid chamber 1211 will move to the common pressure chamber 116 or the secondary side of the common pressure chamber 116 and be discharged from the common liquid chamber 1211.

[0083] According to the liquid ejection head 1 configured in this manner and the liquid ejection device 2 using the liquid ejection head 1, a damper 127 is provided on the ceiling portion 12111 of the common liquid chamber 1211 connected to the common pressure chamber 116. The damper 127 is in contact with the ink in the common liquid chamber 1211, and is deformed by pressure fluctuations of the ink. This allows the damper 127 to suppress pressure fluctuations, and to keep the negative pressure in the common pressure chamber 116 connected to the common liquid chamber 1211 constant, or to keep the negative pressure in the common pressure chamber 116 approximately constant.

[0084] Therefore, the liquid ejection head 1 can suppress pressure fluctuations in the flow paths of the liquid ejection head 1, such as the common liquid chamber 1211, the common pressure chamber 116 which is the secondary side of the common liquid chamber 1211, and the actuator 113. By suppressing pressure fluctuations, the liquid ejection head 1 can achieve high ejection stability.

[0085] Furthermore, the liquid ejection head 1 can further suppress pressure fluctuations by using a suitable shape and material for the damper 127. As a specific example, by making the width W of the damper 127 in the short direction 4 mm or more, the liquid ejection head 1 can further suppress pressure fluctuations, as shown in FIG. 14. By making the thickness of the damper 127 25 μm or less, the liquid ejection head 1 can further suppress pressure fluctuations, as shown in FIG. 16. Furthermore, by making the Young's modulus E of the polyimide film that forms the damper 127 3.4 GPa, the strain area ds can be made larger, and therefore pressure fluctuations can be further suppressed, as shown in FIG. 18.

[0086] Furthermore, the liquid ejection head 1 is configured such that a damper 127 is provided on the ceiling portion 12111 of the common liquid chamber 1211, which faces the supply port 1111 of the substrate 111, which is continuous with the common pressure chamber 116. That is, the liquid ejection head 1 has a simple configuration in which an opening that forms the common liquid chamber 1211 is provided in the manifold 121, and the damper 127 is fixed to the manifold 121 so as to cover this opening. This makes it easy to manufacture the liquid ejection head 1. Furthermore, because the damper 127 is formed in the common liquid chamber 1211 formed by the manifold 121, it is possible to ensure that the damper 127 has an area large enough to come into contact with the common liquid chamber 1211. As such, the liquid ejection head 1 having the damper 127 allows a damper with sufficient performance to be obtained inexpensively and is easy to manufacture.

[0087] According to the liquid ejection head 1 and liquid ejection device 2 configured in this manner, by providing a damper 127 on the ceiling portion 12111 of the common liquid chamber 1211, ejection stability can be improved.

[0088] It should be noted that the embodiments of the present invention are not limited to the above-described configuration. For example, in the above-described example, the head main body 11 is of a non-circulation type, but it may be of a circulation type, or may not have the third common pressure chamber 1163. For example, as another example, when the liquid ejection head 1 is of a non-circulation type or a circulation type, it may not have the third common pressure chamber 1163, and the discharge port 1112 may be provided in the second common pressure chamber 1162.

[0089] In the above embodiment, the liquid ejection head 1 and the liquid ejection device 2 are used in a recording device that ejects ink as a liquid, but the present invention is not limited to this. That is, the liquid ejection head 1 and the liquid ejection device 2 can also be used in, for example, 3D printers, industrial manufacturing machines, and medical applications.

[0090] According to at least one of the embodiments described above, ejection stability can be improved by providing a damper on the ceiling of the common liquid chamber.

[0091] Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, and are also included in the scope of the invention and its equivalents as defined in the claims. The following is a description equivalent to the invention described in the original claims of the present application. [1] A common liquid chamber having an opening; a common pressure chamber connected to the common liquid chamber; an actuator having a plurality of pressure chambers connected to the common pressure chamber; a substrate on which the actuators are provided and which defines the common pressure chamber together with the actuators; a nozzle plate having a plurality of nozzles arranged to face the plurality of pressure chambers, respectively; a damper covering the opening of the common liquid chamber; A liquid ejection head comprising: [2] The liquid ejection head according to [1], wherein the opening of the common liquid chamber covered by the damper is elongated in one direction, and the width of the damper in the short direction is 4 mm or more. [3] The liquid ejection head according to [1] or [2], wherein the damper is a polyimide film formed to a thickness of 25 μm or less. [4] The liquid ejection head according to any one of [1] to [3], wherein the Young's modulus of the damper is 3.4 GPa. [5] The strain area of ​​the damper is 3.18 x 10 -10 The liquid ejection head according to any one of [1] to [4] above. [Explanation of symbols]

[0092] 1...liquid ejection head, 2...liquid ejection device (inkjet recording device), 11...head body, 12...manifold unit, 13...circuit board, 14...cover, 111...substrate, 112...frame body, 113...actuator, 114...nozzle plate, 116...common pressure chamber, 121...manifold, 122...top plate, 123...ink supply pipe, 124...ink discharge pipe, 125...temperature control water supply pipe, 127...damper, 1111...supply port, 1112...discharge port, 1131...pressure chamber, 1133...wall, 1141...nozzle, 1161...first common pressure chamber, 1162...second common pressure chamber, 1163...third common pressure chamber, 1211...common liquid chamber, 1212...discharge flow path, 1213...temperature control flow path, 12 21...opening, 2001...conveying path, 2111...housing, 2112...media supply section, 2113...image forming section, 2114...media discharge section, 2115...conveying device, 2116...temperature control device, 2117...maintenance device, 2118...control section, 2120...support section, 2130...head unit, 2132...supply tank, 2134...pump, 2135...connecting flow path, 12111...ceiling section, 21121...paper feed cassette, 21141...paper output tray, 21161...temperature controlled water tank, 21162...temperature control circuit, 21201...conveying belt, 21202...support plate, 21203...belt roller, 21211 to 21218...guide plate pair, 21221 to 21228...conveying roller, P...paper.

Claims

1. a common liquid chamber having an opening; a common pressure chamber connected to the common liquid chamber; an actuator having a plurality of pressure chambers connected to the common pressure chamber; a substrate on which the actuators are provided and which defines the common pressure chamber together with the actuators; a nozzle plate having a plurality of nozzles arranged to face the plurality of pressure chambers, respectively; a damper covering the opening of the common liquid chamber; Equipped with The strain area of ​​the damper is 3.18 x 10 －１０ A liquid ejection head having a density of m^2 or more.

2. 2. The liquid ejection head according to claim 1, wherein the opening of the common liquid chamber covered by the damper has a shape that is long in one direction, and the width of the damper in the short direction is 4 mm or more.

3. 3. The liquid ejection head according to claim 1, wherein the damper is a polyimide film formed to a thickness of 25 [mu]m or less.

4. 4. The liquid ejection head according to claim 1, wherein the damper has a Young's modulus of 3.4 GPa.

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