Liquid ejection head, device for ejecting liquid and manufacturing method for liquid ejection head

Abstract

To provide a liquid ejection head, a device for ejecting a liquid, and a manufacturing method for the liquid ejection head that are able to prevent a landing position difference between nozzles.SOLUTION: A liquid ejection head includes: a nozzle plate 14 having a nozzle array in which a plurality of nozzles 14a for ejecting liquid are arranged; and a plurality of valve members such as needle valves 8 provided in correspondence with respective nozzles 14a and configured to open and close the corresponding nozzles 14a. Additionally, in the liquid ejection head, when each of the needle valves is positioned at an open position for opening the nozzle, in at least one direction of a nozzle arrangement direction (an X direction) as viewed from a liquid ejection direction (a Z direction) and an orthogonal direction (a Y direction) orthogonal to the nozzle arrangement direction, respective tip ends of all the needle valves (respective centers O3 of sealing members) are shifted to the same side with respect to centers O2 of the nozzles.SELECTED DRAWING: Figure 12

Description

[Technical Field]

[0001] The present invention relates to a liquid ejection head, a liquid ejection device, and a method for manufacturing a liquid ejection head. [Background technology]

[0002] Conventionally, a liquid ejection head is known that includes a nozzle plate having a nozzle row in which a plurality of nozzles that eject liquid are arranged, and a plurality of valve members that are provided corresponding to each nozzle and that open and close the corresponding nozzle.

[0003] Patent Document 1 describes a method for manufacturing a liquid ejection head in which a valve element, which serves as a sealing member made of rubber and disposed at the tip of a needle valve serving as a valve member, is heated while pressed against a nozzle plate to thermally deform the tip of the valve element. According to this method, even if the needle valve is installed at an angle, it is possible to make the gap between the tip of the sealing member and the nozzle plate constant when the needle valve is moved from the closed position to the open position, thereby eliminating unevenness in the flow of liquid into the nozzle and reducing deflection of the ejection. Summary of the Invention [Problem to be solved by the invention]

[0004] However, there is a problem in that the landing positions of droplets from different nozzles are significantly different. [Means for solving the problem]

[0005] In order to solve the above-mentioned problems, the present invention provides a liquid ejection head comprising a nozzle plate having a nozzle row in which a plurality of nozzles that eject liquid are arranged, and a plurality of valve members that are provided corresponding to each nozzle and that open and close the corresponding nozzle, wherein, in at least one of the nozzle arrangement direction when viewed from the liquid ejection direction and an orthogonal direction perpendicular to the nozzle arrangement direction, when the valve members are positioned in an open position that opens the nozzles, the tips of all of the valve members are shifted to the same side relative to the center of the nozzle. [Effects of the Invention]

[0006] According to the present invention, deviation in landing positions between nozzles can be suppressed. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is an external perspective view of a liquid ejection head according to an embodiment of the present invention. [Figure 2] 3A and 3B are diagrams illustrating examples of nozzle arrangements on a nozzle plate. [Figure 3] Cross section AA of Figure 1. [Figure 4] FIG. 2 is a partial detailed view of the liquid dispensing module. [Figure 5] An enlarged view of the area enclosed by dashed line J in Figure 4. [Figure 6] 10A and 10B are diagrams illustrating the ejection of liquid from a nozzle when the center of a sealing member is shifted to the left in the diagram relative to the center of the nozzle. [Figure 7] FIG. 10 is a diagram illustrating a conventional deviation in landing position between nozzles. [Figure 8] A graph showing the relationship between the ratio (a / b) of the gap a between the sealing member on the separating side and the valve seat portion relative to the nozzle center at the center of the tip of the sealing member in a cross section parallel to the direction of displacement of the sealing member relative to the nozzle, and the gap b between the sealing member on the opposite side to the separating side and the valve seat portion, and the bending angle of the ejected liquid. [Figure 9] 1(a) is a diagram showing the state when the ratio (a / b) of the gap a between the sealing member and the valve seat on the side away from the nozzle center of the center of the sealing member in a cross section parallel to the direction of displacement of the sealing member relative to the nozzle is 1, (b) is a diagram showing the state when the ratio is 0.5, and (c) is a diagram showing the state when the ratio is 0. [Figure 10] 10A and 10B are diagrams illustrating the effect of misaligning the tip of the needle valve relative to the nozzle in a direction perpendicular to the nozzle arrangement direction. [Figure 11]10 is a graph showing the relationship between the pressing force required to move the needle valve to the sealing position for each rod material and the amount of correction for positional deviation of the sealing member. [Figure 12] The needle valve is shown in an open position that opens the nozzle. [Figure 13] 5A and 5B are diagrams illustrating the behavior of the tip of the needle valve when the needle valve is moved from an open position to a closed position and then moved back to the open position. [Figure 14] FIG. 10 is a diagram illustrating a first modified example. [Figure 15] 10A and 10B are diagrams illustrating the behavior of the tip of the needle valve when the needle valve in Modification 1 is moved from the open position to the closed position and then moved back to the open position. [Figure 16] FIG. 10 is a diagram illustrating a second modified example. [Figure 17] 10A and 10B are diagrams illustrating the behavior of the tip of the needle valve when the needle valve in Modification 2 is moved from a closed position to an open position. [Figure 18] FIG. 10 is a diagram illustrating a third modified example. [Figure 19] 10A and 10B are diagrams illustrating the behavior of the needle valve in Modification 3 when it is moved from an open position to a closed position. [Figure 20] 3A to 3C are diagrams illustrating an example of a manufacturing method according to this embodiment and modified examples 1 and 2. [Figure 21] 10A to 10C are diagrams illustrating an example of a manufacturing method according to Modification 3. [Figure 22] FIG. 10 is a diagram showing the tip of a needle valve in which the tip of the sealing member is conical. [Figure 23] FIG. 1 is a schematic perspective view of a device for discharging liquid. [Figure 24] FIG. 1 is a diagram showing an example of a supply device that supplies paint to a plurality of liquid ejection heads included in a device that ejects liquid. [Figure 25] FIG. 1 is a diagram showing an example of an electrode manufacturing apparatus as a liquid ejection apparatus equipped with a liquid ejection head according to the present embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0008] The best mode for carrying out the present invention will be described below with reference to the drawings. Note that a person skilled in the art can easily modify or alter the present invention within the scope of the claims to create other embodiments, and these modifications and alterations are included within the scope of the claims. The following description is an example of the best mode for carrying out the present invention and does not limit the scope of the claims.

[0009] FIG. 1 is a perspective view showing the appearance of a liquid ejection head 10 according to this embodiment. In the following explanation, the nozzle arrangement direction (longitudinal direction of the liquid ejection head) is defined as the X direction, the liquid ejection direction from the nozzle (height direction of the liquid ejection head) is defined as the Z direction, and the direction perpendicular to both the X and Z directions (short direction of the liquid ejection head) is defined as the Y direction.

[0010] The liquid ejection head 10 has a nozzle plate 14, a flow path member 15, and a cover 11 serving as a housing member. One end of the flow path member 15 in the X direction is provided with a supply port 12 through which the liquid is supplied, and the other end of the flow path member 15 in the X direction is provided with a discharge port 13 through which the liquid is discharged. In addition, a harness passage hole 16 is provided in the upper part of the cover 11, through which a harness for communicating with the actuator 2 housed in the cover passes.

[0011] The nozzle plate 14, flow path member 15, and cover 11 are made of metal, resin, or ceramic. The cover 11 accommodates and supports a liquid ejection module 1 (see FIG. 4), which will be described later, inside. The flow path member 15 defines a flow path through which the liquid flows, and the nozzle plate 14 has a plurality of nozzles for ejecting the liquid. The nozzle plate 14 is mechanically (removably) fixed to the flow path member 15, and the cover 11 is mechanically (removably) fixed to the flow path member 15.

[0012] FIG. 2 is a diagram illustrating an example of the arrangement of nozzles in the nozzle plate 14. As shown in FIG. As shown in Fig. 2(a), one nozzle row can be provided in the center of the nozzle plate in the Y direction (short direction of the head), or as shown in Fig. 2(b), two nozzle rows can be provided in the Y direction by arranging the nozzles 14a in a staggered manner. Note that the nozzle arrangement shown in Fig. 2 is just one example, and for example, two sets of two nozzle rows in the Y direction arranged in a staggered manner may be provided, for a total of four nozzle rows, or multiple nozzle rows may be provided in which the nozzles are positioned at the same position in the X direction (longitudinal direction of the head). The liquid ejection head of the embodiment described below has two nozzle rows in the Y direction by arranging the nozzles 14a shown in Fig. 2(b) in a staggered manner.

[0013] 3 is a cross-sectional view taken along line AA in FIG. 1, and FIG. 4 is a partial detailed view of the liquid dispensing module 1. As shown in FIG. A plurality of liquid ejection modules 1, each corresponding to a nozzle 14a, are housed in two staggered rows in the housing section 11a of the cover 11. Each liquid ejection module 1 includes a needle valve 8, which serves as a valve member for opening and closing the nozzle 14a, and a movement mechanism 6 having an arm member 3 and an actuator 2. The needle valve 8 is made up of a rod 8b, which serves as an axial member, and a sealing member 8a, which seals the nozzle 14a.

[0014] The plurality of liquid ejection modules 1 are arranged in two rows in the accommodation portion 11a of the cover 11, staggered in the X direction with the needle valves 8 facing each other. Furthermore, the plurality of liquid ejection modules 1 are arranged so that the arm members 3 partially overlap when viewed from the X direction, as shown in Fig. 3. Here, the case where the nozzles 14a are arranged in two staggered rows on the nozzle plate 14 as shown in Fig. 2(b) has been described, but even when the nozzles 14a are arranged in a single row on the nozzle plate 14 as shown in Fig. 2(a), the plurality of liquid ejection modules 1 are arranged so that the arm members 3 partially overlap when viewed from the X direction.

[0015] Here, staggered arrangement of liquid ejection modules can also be said to mean that a liquid ejection module in which the actuator 2 is located on one side of the nozzle array and a liquid ejection module in which the actuator 2 is located on the other side of the nozzle array are arranged facing each other, and are arranged along the nozzle array direction (X direction) so that portions of the arm members 3 overlap each other when viewed from the nozzle array direction (X direction).

[0016] The actuator 2 comprises a piezoelectric element 2a and a fixing element 2b that applies a preload to compress the piezoelectric element 2a and also serves to fix the element, and the fixing element 2b is fixed to the inner wall surface perpendicular to the Y direction of the housing portion 11a of the cover 11. More specifically, the fixing element 2b fixes the end of the piezoelectric element 2a in the Z direction, which is the direction in which the piezoelectric element 2a expands and contracts, to the inner wall surface of the housing portion 11a. The fixing method is mechanical fixing using screws or the like, or chemical fixing such as bonding with an adhesive or thermal diffusion.

[0017] The arm member 3 is rotatably supported on a support shaft 4 serving as an arm support portion, one end of which is adhesively fixed to the actuator 2, and the other end of which is in contact with an arm receiving portion 8c fixed to the needle valve 8. A contact portion 3a serving as a second connecting portion that contacts the arm receiving portion 8c at the other end of the arm member 3 is hemispherical and protrudes toward the arm receiving portion 8c, or is crescent-shaped when viewed from the X direction, so that it smoothly contacts the arm receiving portion 8c when the arm member 3 rotates.

[0018] Furthermore, an escape hole 3b through which the needle valve 8 passes is formed at the other end of the arm member 3. The inner diameter of the escape hole 3b is larger than the outer diameter of the needle valve 8, so that the needle valve 8 does not come into contact with the arm member 3 when the arm member 3 rotates.

[0019] A plurality of valve through-holes 11b are provided in the bottom surface of the accommodation portion 11a of the cover 11, through which needle valves 8 provided corresponding to each nozzle 14a pass. A seal member 19 such as an O-ring is provided at the end of each valve through-hole 11b on the flow path member 15 side, and a valve receiving portion 20 that slidably receives the needle valve 8 is provided on the side opposite the end of the valve through-hole 11b on the flow path member 15 side. In addition, the end of the needle valve 8 opposite the nozzle plate side passes through a spring receiving plate 18. The needle valve 8 is held in a position parallel to the Z direction by the seal member 19, valve receiving portion 20, and spring receiving plate 18.

[0020] A compression spring 7 is provided as a biasing means between the arm receiving portion 8c fixed to the needle valve 8 and the spring receiving plate 18, and biases the needle valve 8 toward the nozzle plate 14 via the arm receiving portion 8c.

[0021] The compression spring 7 biases the needle valve 8 toward the nozzle plate 14, thereby stabilizing the movement of the needle valve 8 between an open position where the nozzle is opened and a closed position where the nozzle is closed. The spring support plate 18 is attached to a fixing member 17 fixed to the cover 11.

[0022] 3, the actuator 2 of each liquid ejection module 1 is connected via a harness to a drive control device 40. The drive control device 40 has a waveform generating circuit 41 and an amplifier circuit 42, which are drive pulse generating units.

[0023] A waveform generating circuit 41 generates a drive pulse waveform, which will be described later, and an amplifier circuit 42 amplifies the voltage value to a required value. The amplified voltage signal is then applied to the actuator 2. By applying this voltage, a drive control device 40 controls the displacement of the piezoelectric element 2a and the opening and closing of the nozzle 14a of the needle valve 8. This controls the ejection of liquid from the liquid ejection head 10. However, if the waveform generating circuit 41 can apply a sufficient voltage, the amplifier circuit 42 may be omitted.

[0024] In this embodiment, the actuator 2 has a normally closed configuration, and when no signal is supplied from the drive control device 40 to the actuator 2, the needle valve 8 closes the nozzle 14a due to the biasing force of the compression spring 7. Here, when no signal is supplied to the actuator 2, it may be a situation where either zero voltage is always applied or a constant static voltage is always applied.

[0025] The waveform generating circuit 41 generates a drive pulse, which is a waveform that varies over time with the voltage applied to the actuator 2. The waveform generating circuit 41 receives print data, for example, from an external PC or a microcomputer inside the device, and generates a drive pulse based on this input data. The waveform generating circuit 41 can change the voltage applied to the actuator 2 and can generate multiple drive pulses. As described above, when the waveform generating circuit 41 generates a drive pulse, the piezoelectric element 2a of the actuator 2 expands and contracts in accordance with the drive pulse.

[0026] Specifically, when a predetermined voltage is applied to the piezoelectric element 2a, the piezoelectric element 2a expands. When the piezoelectric element 2a expands, the other end of the arm member 3 rotates the arm member 3 in a direction that lifts the arm receiving portion 8c. As a result, the arm receiving portion 8c rises (moves toward the spring receiving plate 18) against the biasing force of the compression spring 7, and the needle valve 8 rises together with the arm receiving portion 8c. This opens the nozzle 14a, and droplets are ejected from the nozzle 14a due to the pressure applied to the liquid in the flow path 5.

[0027] As the voltage applied to the piezoelectric element 2a decreases, the piezoelectric element 2a contracts. As the piezoelectric element 2a contracts, the arm member 3 rotates so that the other end of the arm member 3 moves downward (toward the nozzle plate). Then, the biasing force of the compression spring 7 causes the arm receiving portion 8c to move downward so as to follow the movement of the other end of the arm member 3, and the nozzle 14a is blocked by the needle valve 8, stopping the ejection of droplets from the nozzle 14a.

[0028] In this embodiment, a piezoelectric element 2a is used as the actuator 2, but the actuator 2 may also be an electrically driven device such as a pneumatically driven piston equipped with a solenoid or an electromagnetic valve. In this embodiment, a compression spring 7 is used, but a tension spring that pulls the needle valve 8 toward the nozzle plate may also be used. In this case, for example, one end of the tension spring may be fixed to the bottom surface of the housing portion 11a, and the other end in an extended state may be fixed to the needle valve 8 or the arm receiving portion 8c. In this embodiment, the displacement of the actuator is transmitted to the needle valve via the arm member, but the needle valve may be connected to the actuator, and the displacement of the actuator may be transmitted directly to the needle valve.

[0029] FIG. 5 is an enlarged view of the area surrounded by the dashed line J in FIG. As shown in FIG. 5, the sealing member 8a is spherical and elastically held in a recess 8b1 at the nozzle-side end of the rod 8b of the needle valve 8. Specifically, the sealing member 8a is brought into contact with the bottom surface of the recess 8b1, and a liquid or gel-like elastic member 30 is poured into the recess 8b1 and cured, thereby holding the sealing member 8a in the recess 8b1 via the elastic member 30. The elastic member 30 is made of a material with a low elastic modulus, such as rubber or resin. A material with low elasticity, high breaking elongation, solvent resistance, and consideration for the manufacturing process described below is preferred for the elastic member 30. In this embodiment, a UV-curable fluororubber (Shin-Etsu Chemical) is used for the elastic member 30.

[0030] The diameter of rod 8b is 2.0 mm, and the inner diameter of recess 8b1 is 1.4 mm. The depth of recess 8b1 is 0.5 mm, and the diameter of spherical sealing member 8a is 0.8 mm, with a circularity of ±0.001 mm. Thus, the depth of recess 8b1 is greater than the radius of sealing member 8a. Elastic member 30 is positioned up to the opening surface of recess 8b1 (the lower surface of the rod), and holds sealing member 8a at a distance greater than the radius. This creates an anchor effect that makes sealing member 8a less likely to come off rod 8b.

[0031] As described above, the sealing member 8a is held in contact with the bottom surface of the recess 8b1. By holding the sealing member 8a in contact with the rod 8b in the Z direction (the direction in which the needle valve opens and closes), the positional accuracy in the Z direction can be improved, and the gap between the tip of the sealing member 8a and the nozzle plate 14 when the nozzle is open can be made a specified gap. This allows the nozzle 14a to eject a desired amount of liquid. Furthermore, high positional accuracy in the Z direction can improve sealing performance.

[0032] The rod 8b is made of stainless steel (SUS) and has a cylindrical shape with a length of 20 mm. The nozzle plate 14 has a thickness of 0.6 mm and a valve seat 14d that serves as a guide against which the sealing member 8a abuts and guides the sealing member 8a so that the center of the sealing member 8a approaches the center of the nozzle. The valve seat 14d has a bottom that communicates with the nozzle 14a and is generally cone-shaped with a diameter that increases upward (toward the needle valve). The sealing member 8a and the valve seat 14d may be coated with a ceramic coating or a diamond-like coating to improve sliding properties and durability.

[0033] If the sealing member 8a is made of rubber or plastic, it will elastically deform and come into contact with the valve seat 14d. However, if the actuator is driven at a drive frequency of several kilohertz, the elastic deformation of the sealing member 8a cannot keep up, resulting in a small elastic deformation when the nozzle is closed, which may result in an inability to properly seal the nozzle 14a. Furthermore, if the nozzle 14a is closed for a long period of time (several minutes to several months), it takes time for the elasticity of the sealing member 8a to recover. As a result, the nozzle 14a may not be properly sealed when driven (during liquid ejection). Furthermore, as the elastic deformation recovers, the gap between the nozzle plate 14 and the sealing member 8a narrows when the nozzle is open, which may result in a change in the amount of liquid ejected from the nozzle 14a.

[0034] Therefore, it is preferable to use a hard material such as metal or ceramic for the sealing member 8a. This prevents the sealing performance of the sealing member 8a from deteriorating even when the actuator is driven at a high driving frequency, and allows the nozzle to be sealed well. In this embodiment, the sealing member 8a is made of zirconia.

[0035] Because the sealing member 8a is made of a hard material such as metal or ceramic, the sealing member 8a makes line contact with the valve seat 14d to seal the nozzle 14a. In this way, the sealing member 8a makes line contact with the valve seat 14d to seal the nozzle 14a, thereby eliminating solids contained in the liquid at the sealing point of the sealing member 8a (the point of contact with the valve seat 14d), thereby sealing the nozzle 14a well.

[0036] Generally, the needle valve 8 and the nozzle plate 14 are assembled to the housing so that the center of the sealing member 8a, which is the tip of the needle valve 8, is aligned with the center of the nozzle. However, even when assembly is performed with high precision, it is not possible to completely eliminate the misalignment of the sealing member 8a with respect to the center of the nozzle 14a. If the center of the sealing member 8a is misaligned with the center of the nozzle 14a, when the needle valve 8 is moved in the direction from the nozzle sealing state to the direction of opening the nozzle 14a, the side of the sealing member 8a opposite to the side where the center of the sealing member 8a is separated from the nozzle center (the side where the center of the sealing member is misaligned, hereinafter simply referred to as the misaligned side) will first separate from the valve seat 14d.

[0037] FIG. 6 is a diagram illustrating the ejection of liquid from the nozzle 14a when the center O3 of the sealing member 8a is shifted to the left (+X direction) in the figure with respect to the center O2 of the nozzle 14a. When the center O3 of the sealing member 8a is shifted to the left side in the figure relative to the center O2 of the nozzle 14a, when the needle valve 8 is moved in the direction from the nozzle sealing state to opening the nozzle 14a, the right side (-X direction side) of the sealing member 8a in the figure moves away from the valve seat portion 14d first.

[0038] 6, the right side of the sealing member 8a in the figure separates from the valve seat portion 14d first, so that liquid flows into the nozzle 14a from the right side in the figure, and the pressure on the right side of the nozzle 14a in the figure increases. When the liquid is a normal incompressible material, the liquid flows inside the nozzle from the right side in the figure, where the pressure is high, to the left side in the figure, where the pressure is low. As a result, the liquid is ejected from the nozzle 14a in a diagonal direction to the left in the figure (the direction in which the center of the sealing member 8a is misaligned).

[0039] On the other hand, if the liquid to be ejected is a compressible or nonlinear material (especially a plastic material) that remembers the history of applied force, the liquid entering the nozzle 14a from the right side of the figure will be bent counterclockwise within the nozzle. At this time, the ejected liquid is forcibly oriented along the flow (stretched in the flow direction). In the case of a compressible or nonlinear liquid, the liquid remembers this orientation, i.e., the orientation state is preserved in the liquid. A compressible or nonlinear liquid is compressed on the inner wall of the nozzle on the ejection side and flows straight downward in the figure. When it exits the nozzle 14a and the compression is released, the liquid attempts to return to the counterclockwise direction in the figure due to its remembered orientation. As a result, the liquid is ejected from the nozzle 14a diagonally to the right in the figure (opposite the side away from the center of the sealing member 8a relative to the nozzle center). If the ejected liquid is water-based paint, which contains a large amount of emulsified plastic, the liquid is ejected on the side opposite the side away from the center of the sealing member relative to the nozzle center.

[0040] When the needle valve 8 and the nozzle plate 14 are assembled so that the center of the sealing member coincides with the center of the nozzle, there is a possibility that the center of the sealing member may be misaligned in any direction over 360° relative to the center of the nozzle due to assembly errors, etc. Therefore, as shown in FIG. 7, it is not known in which direction the liquid will be ejected from the nozzle 14a. As a result, the direction of deviation of the liquid landing position relative to the nozzle 14a differs for each nozzle. Therefore, for one nozzle, the liquid landing position may be significantly deviated to the right in FIG. 7, and for another nozzle, the liquid landing position may be significantly deviated to the left in FIG. 7. As shown in FIG. 7, there is a risk that the landing position may be misaligned by up to a mm between nozzles.

[0041] Therefore, in this embodiment, when the needle valves are in the open position, the tips (sealing members 8a) of all needle valves 8 are shifted to the same side relative to the center of the nozzles 14a in at least one of the X and Y directions, so that the liquid ejected from all nozzles 14a bends in the same direction in at least one of the X and Y directions.

[0042] If the center of sealing member 8a, which is the tip of the needle valve, is assembled at a position shifted to a predetermined side in at least one of the X and Y directions relative to the center of nozzle 14a, the maximum amount of deviation of the center of the sealing member from the center of the nozzle will be large if the assembly accuracy is equivalent to that in Figure 7. However, even if the maximum amount of deviation is large, the bending angle of the liquid (the angle with respect to the vertical direction of nozzle plate 14) will not increase accordingly.

[0043] Figure 8 is a graph showing the relationship between the ratio (a / b) of the gap a between the sealing member 8a on the deviation side (separation side) of the sealing member center from the nozzle center and the valve seat portion 14d in a cross section parallel to the deviation direction (separation direction) of the center of the sealing member from the nozzle center to the gap b between the sealing member 8a on the opposite side to the deviation side (separation side) and the valve seat portion 14d, and the bending angle of the ejected liquid. As shown in Figure 9(a), when the center O3 of the sealing member 8a and the center O2 of the nozzle 14a are aligned, the gap ratio (a / b) is 1. As can be seen from the Hagen-Poiseuille equation, the flow rate of a liquid is proportional to the square of the gap. A narrower gap results in a slower flow rate, while a wider gap results in a faster flow rate. The liquid that flows into the nozzle 14a tends to bend toward the slower flow rate due to the combined forces and the inertial force of the liquid. When the center O1 of the needle valve 8 and the center O2 of the nozzle 14a are aligned and the gap ratio (a / b) is 1, the liquid flows at the same rate into the nozzle 14a, canceling out each other's forces, and the liquid is ejected perpendicular to the nozzle plate 14 (bending angle 0°).

[0044] When the center O3 of the sealing member 8a is shifted relative to the center O2 of the nozzle 14a, as shown in FIG. 9(b), the gap a between the sealing member 8a and the valve seat 14d on the shifted side (the side separated from the nozzle center O2) of the sealing member center O3 narrows, and the gap b on the opposite side to the shifted side increases, decreasing the gap ratio (a / b). As a result, the difference in flow velocity between the liquid flowing into the nozzle 14a from the gap a on the shifted side and the liquid flowing into the nozzle 14a from the gap b on the opposite side to the shifted side increases. As a result, the bending angle increases as the gap ratio (a / b) decreases.

[0045] On the other hand, if the center of the needle valve 8 is further shifted from the center of the nozzle 14a and the gap ratio (a / b) falls below 0.5, the flow rate of the liquid flowing from the shifted side of the sealing member 8a with a narrower gap to the nozzle 14a decreases, the effect of the flow velocity difference is reduced, and the discharge bending angle becomes smaller. As shown in Figure 9(c), if the center of the sealing member 8a is shifted significantly and the gap ratio (a / b) becomes 0, the effect of the flow velocity difference disappears and the bending becomes smaller.

[0046] Thus, when the misalignment of the sealing member 8a with respect to the nozzle 14a exceeds a certain value (a misalignment where the gap ratio (a / b) is 0.5), the angle of the liquid deflection decreases. Therefore, when the sealing member center O3 is displaced a predetermined distance from the nozzle center O2, taking into account assembly accuracy, so that the misalignment direction of the center O3 of the sealing member 8a (the tip position of the needle valve) with respect to the nozzle center O2 is the same in at least one of the X and Y directions, the ejected liquid deflects only to the extent shown in FIG. 6 at most. Therefore, by configuring the tips (sealing members 8a) of all needle valves 8 so that they are displaced in the same direction with respect to the nozzle 14a, the maximum droplet position deviation between the nozzles is b mm, as shown in FIG. 6. As a result, the maximum droplet impact position deviation can be halved compared to the case shown in FIG. 7.

[0047] The center O3 of the sealing member 8a, which is the tip position of the needle valve 8, is the central axis parallel to the Z-axis direction (the central axis O2 of the nozzle 14a (FIG. 6, etc.)). The relative position of the center O3 of the sealing member with respect to the center O2 of the nozzle on the XY plane is the "tip position of the needle valve with respect to the nozzle."

[0048] Furthermore, by offsetting the center O3 of the sealing member 8a, which is the tip of the needle valve 8, from the center O2 of the nozzle 14a, there is also the effect of increasing the flow rate of liquid flowing through the nozzle 14a compared to when the center O3 of the sealing member 8a and the center O2 of the nozzle 14a are aligned. The following equation 1 is a formula for calculating the flow rate Q flowing through the annular gap between the sealing member 8a and the valve seat 14d when the center O3 of the sealing member 8a and the center O2 of the nozzle 14a are aligned. The following equation 2 is a formula for calculating the flow rate Q flowing through the annular gap when the center O3 of the sealing member 8a and the center O2 of the nozzle 14a are offset, causing eccentricity in the annular gap between the sealing member 8a and the valve seat 14d.

[0049]

number

number

[0050] The above D is the diameter of the sealing member 8a, and δ is the annular gap between the sealing member 8a and the valve seat 14d when the centers of the sealing member 8a and the valve seat 14d are aligned. Δp is the differential pressure between the inlet and outlet of the annular gap, and l is the distance between the inlet and outlet of the annular gap. Furthermore, the above ε is the amount of eccentricity (the amount of misalignment between the center of the sealing member 8a and the center of the valve seat 14d (nozzle 14a)), and μ is the viscosity coefficient of the liquid.

[0051] As can be seen from a comparison of the above equations 1 and 2, when the center of the sealing member 8a and the center of the nozzle 14a are misaligned, causing eccentricity in the annular gap between the sealing member 8a and the valve seat portion 14d, the flow rate flowing into the nozzle 14a can be increased.

[0052] In this embodiment, as shown in FIG. 10, the liquid ejection head 10 is arranged so that the nozzle arrangement direction is parallel to the sub-scanning direction, and liquid is ejected while the liquid ejection head 10 is moved in the main scanning direction.

[0053] If the sealing member 8a, which is the tip of the needle valve 8, is misaligned in the Y direction (a direction perpendicular to the nozzle arrangement direction) relative to the nozzle 14a, the landing position will vary in the main scanning direction, as shown in Figure 10(a). As a result, the drawing start position will vary in the main scanning direction, as shown in Figure 10(a). However, by controlling the ejection timing for each nozzle based on the amount of landing position deviation (the distance in the main scanning direction between the center of the nozzle 14a and the landing position), it is possible to eliminate the landing position deviation between nozzles, as shown in Figure 10(b).

[0054] On the other hand, if the sealing member 8a, which is the tip of the needle valve 8, is misaligned in the nozzle arrangement direction (X direction) relative to the nozzle 14a, the spacing between the dots in the sub-scanning direction will vary. If there is variation in the spacing, the image may be perceived as having streaks. This variation in the spacing between the dots in the sub-scanning direction cannot be corrected by control or the like.

[0055] Therefore, of the X and Y directions, the direction in which the displacement of the sealing member 8a relative to the nozzles is aligned is preferably the X direction (sub-scanning direction). This causes the liquid ejected from each nozzle to bend in the same direction in the sub-scanning direction, and as explained using Figure 6, it is possible to limit the deviation in landing position between nozzles to a maximum of b mm (a > b). This makes it possible to reduce variations in the spacing of the drawing in the sub-scanning direction, and to prevent streaks from being recognized in the image.

[0056] On the other hand, in the Y direction (main scanning direction), the misalignment direction of the sealing member 8a relative to the nozzles cannot be aligned, and as explained using Figure 7, there is a risk of misalignment of the landing position of droplets occurring by a mm, which is twice as much as in the X direction (sub-scanning direction). However, as described above, by controlling the ejection timing for each nozzle, it is possible to eliminate the misalignment of the landing position between nozzles, as shown in Figure 10(b).

[0057] In this way, by aligning the misalignment of the sealing member 8a, which is the tip of the needle valve 8, relative to the nozzle 14a in the nozzle arrangement direction (X direction), it is possible to reduce variation in the spacing in the drawing sub-scanning direction, and thereby suppress deterioration in image quality.

[0058] Furthermore, if the liquid is a thixotropic fluid such as paint, the flow of the liquid into the nozzle 14a is hardly affected by the gap between the sealing member 8a and the valve seat 14d, and the liquid continues to flow through the gap that first opens. This is because the liquid flows through the gap where the sealing member 8a first separates from the valve seat 14d, shearing the liquid and reducing its viscosity. In addition, in this embodiment, the sealing member 8a is spherical, with a shape that gradually narrows the gap toward the separation point in the direction of liquid flow. This creates a wedge effect, causing the elastic member 30, which elastically holds the sealing member 8a to the rod 8b, to elastically deform with small pressure, widening the gap between the sealing member 8a and the valve seat 14d. Therefore, the liquid continues to flow through the gap that first opens.

[0059] For example, although this depends on conditions such as the liquid viscosity and pressure, under the conditions of this embodiment, where the viscosity is 10 mPa·s and the liquid pressure is 0.5 MPa, a gap of 0.001 mm will cause the thixotropic fluid to begin flowing toward the nozzle 14a. Therefore, under these conditions, if the sealing member 8a, which is the tip of the needle valve 8, is shifted by 0.001 mm or more relative to the nozzle 14a, the portion of the sealing member 8a opposite the offset side (separation side) relative to the center of the nozzle will first separate from the valve seat 14d by 0.001 mm or more, and then the offset side will separate from the valve seat. As a result, in the case of a thixotropic fluid, the liquid continues to flow toward the nozzle 14a from the gap on the opposite side of the sealing member 8a opposite the offset side, allowing the liquid to be bent in the desired direction when being ejected from the nozzle 14a.

[0060] Considering normal processing accuracy and assembly accuracy, it is preferable that the deviation between the target needle valves 8 and the nozzles 14a be about 0.1 mm. By setting the deviation to this amount, the sealing members 8a, which are the tips of all the needle valves, can be shifted to the same side relative to the nozzles 14a.

[0061] Furthermore, if the liquid is not a thixotropic fluid such as paint, if the offset side of the center of the sealing member 8a relative to the nozzle center moves away from the valve seat 14d during movement from the closed position to the open position, liquid will flow in through the gap on the offset side, causing the discharge deflection angle to become unstable. Therefore, if the liquid is not a thixotropic fluid, it is preferable to keep the sealing member 8a in contact with the valve seat 14d during movement from the closed position to the open position. For example, if the tilt angle θ of the valve seat 14d relative to the Z direction is 30° and the movement amount L of the needle valve 8 is 0.1 mm, the sealing member 8a should be offset from the nozzle 14a by approximately 0.06 mm (≒ L × tan θ).

[0062] As will be described later, when moving from the open position to the closed position, the sealing member 8a makes partial contact with the valve seat 14d. The needle valve 8 then descends while being guided by the valve seat 14d, which serves as a guide, to move the center of the sealing member 8a closer to the center of the nozzle 14a (while correcting the positional deviation of the sealing member 8a). A side effect of this is a shortened service life of the components due to impact force and wear. The greater the deviation of the sealing member 8a, which is the tip of the needle valve 8, from the nozzle 14a, the greater the impact force and contact pressure when the sealing member 8a makes partial contact with the valve seat 14d. Therefore, it is necessary to determine the amount of deviation of the needle valve 8 from the nozzle 14a while assessing the impact position and durability.

[0063] In this embodiment, as described above, the sealing member 8a is elastically held to the rod 8b by the elastic member 30. This allows the elastic member 30 to elastically deform and absorb the impact when the sealing member 8a makes partial contact with the valve seat 14d. Furthermore, the elastic deformation of the elastic member 30 reduces the contact pressure between the sealing member 8a and the valve seat 14d when moving from the open position to the closed position. This prevents the shortening of the lifespan of components due to impact force, wear, etc., and increases the tolerance for misalignment of the tip of the needle valve 8 (sealing member 8a) with respect to the nozzle 14a.

[0064] Furthermore, the rod 8b bends to correct misalignment (alignment) of the sealing member 8a when moving from the open position to the sealing position. Therefore, depending on the material and diameter of the rod 8b, if the tip of the needle valve 8 (sealing member 8a) is significantly misaligned with respect to the nozzle 14a, the load when moving from the open position to the sealing position also increases. This increases the load on the actuator 2. To ensure smooth movement to the sealing position even with such a large load, it becomes necessary to pass a high voltage current through the piezoelectric element 2a or to enlarge the piezoelectric element 2a, which leads to increased power consumption and an increase in the size of the liquid ejection head 10. Therefore, the load when moving from the open position to the sealing position must be minimized.

[0065] Fig. 11 is a graph showing the relationship between the pressing force required to move the needle valve 8 to the sealing position and the amount of correction for positional deviation of the sealing member 8a. Fig. 11 also shows the results when the material of the rod 8b is SUS (stainless steel), Zr (zirconium), or an ultra-hard material. 11, when the material of the rod 8b is SUS (stainless steel), the amount of positional deviation correction of the sealing member 8a in response to the pressing force (the amount of movement of the sealing member 8a toward the nozzle) is the largest. Therefore, by using SUS as the material of the rod, the load when moving to the sealing position can be reduced compared to when using Zr (zirconium) or an ultra-hard material, and an increase in the load on the actuator 2 can be suppressed, which is preferable.

[0066] FIG. 12 shows the needle valve 8 in the open position which opens the nozzle. 12, the deviation between the center O3 of the sealing member 8a and the center O1 of the rod 8b is within ±0.005 mm, and the center of the sealing member 8a is aligned approximately with the center of the rod 8b. The center of the needle valve 8 (rod 8b) is offset by 0.02 mm from the center of the nozzle 14a in the direction perpendicular to the nozzle arrangement direction (Y direction). The deviation between the center of the nozzle 14a and the center of the valve seat 14d is 1 μm or less. In FIG. 12, even when the needle valve 8 is in the open position that opens the nozzle 14a, the offset side (separate side) of the center of the sealing member 8a relative to the center of the nozzle 14a is in contact with the valve seat portion 14d.

[0067] FIG. 13 is a diagram illustrating the behavior of the tip of the needle valve 8 when the needle valve 8 is moved from the open position to the closed position and then moved back to the open position. Figure 13(a) shows the needle valve 8 moving from the open position to the closed position, Figure 13(b) shows the needle valve 8 in the closed position, Figure 13(c) shows the needle valve 8 moving from the closed position to the open position, and Figure 13(d) shows the needle valve 8 in the open position.

[0068] The needle valve 8 descends from the open position to the closed position while the sealing member 8a is in partial contact with the valve seat 14d only on the offset side (left side in the figure) of the center of the nozzle. At this time, the sealing member 8a receives a reaction force from the valve seat 14d in the Y direction toward the center of the nozzle (right side in the figure). This reaction force bends the needle valve 8 (rod 8b), tilting its tip. As a result, the sealing member 8a slides against the valve seat 14d and descends, guided so that the center O3 of the sealing member 8a approaches the center O2 of the nozzle 14a, as shown by the arrow in Figure 13(a). At this time, the elastic member 30, which elastically holds the sealing member 8a to the rod 8b, elastically deforms, moving the sealing member 8a in the Y direction (right side in the figure). This reduces the contact pressure between the sealing member 8a and the valve seat 14d, thereby suppressing wear on the sealing member 8a and the valve seat 14d.

[0069] Then, as shown in Figure 13(b), when the needle valve 8 is positioned in the sealing position, the center O3 of the sealing member 8a approximately coincides with the center O2 of the nozzle 14a, and the sealing member 8a makes line contact with the valve seat portion 14d to seal the nozzle 14a.

[0070] In this way, when sealed, the positional deviation between the center O2 of the nozzle 14a and the center O3 of the sealing member 8a is reduced compared to when open, and the center O3 of the sealing member 8a is approximately aligned with the center O2 of the nozzle 14a. This allows the contact pressure between the sealing member 8a and the valve seat portion 14d to be uniform and the nozzle 14a to be sealed well. Here, the alignment of the center O3 of the sealing member 8a with the center O2 of the nozzle 14a means that they are aligned within the XY plane.

[0071] As shown in FIG. 13(c), when the needle valve 8 moves from the closed position to the open position, the opposite action is taken. That is, when the needle valve 8 rises, the restoring force of the deflected rod 8b causes the sealing member 8a to move laterally toward the offset side (left side in the figure) of the nozzle 14a relative to the center of the sealing member. As a result, the sealing member 8a maintains contact with the valve seat 14d on the offset side (left side in the figure) of the nozzle 14a relative to the center of the sealing member. Meanwhile, on the opposite side (right side in the figure) of the nozzle 14a relative to the offset side, the sealing member 8a separates from the valve seat 14d, creating a gap between the sealing member 8a and the valve seat 14d. As a result, liquid flows out toward the nozzle 14a on the opposite side (right side in the figure). Then, as shown in FIG. 13(d), the needle valve 8 maintains contact between the sealing member 8a and the valve seat 14d on the offset side (left side in the figure) of the nozzle 14a of the needle valve 8, moving to the open position.

[0072] In the first embodiment, the displaced side (left side in the figure) of the sealing member 8a is always in contact with the valve seat 14d while moving from the closed position to the open position. This prevents almost no liquid from flowing into the nozzle 14a from the displaced side of the sealing member. This allows the liquid ejected from the nozzle 14a to bend more stably.

[0073] In the above description, the tip of the rod 8b is tilted due to the deflection of the rod 8b, but the rod may be tilted by rotating around its upper end as a fulcrum. In this case, when moving from the closed position to the open position, the rod 8b rotates in a direction that reduces the tilt due to its own weight, and the sealing member 8a on the side opposite to the misaligned side of the needle valve 8 moves away from the valve seat 14d.

[0074] Next, a modified example will be described. [Variation 1] FIG. 14 is a diagram illustrating the first modification. FIG. 14 shows the needle valve 8 in the open position which opens the nozzle. 14, in Modification 1, the positional deviation between the center O3 of the sealing member 8a and the center O2 of the nozzle 14a is smaller than the positional deviation between the center O1 of the needle valve 8 (rod 8b) and the center O2 of the nozzle. Specifically, the positional deviation between the center O3 of the sealing member 8a and the center O2 of the nozzle 14a is 0.01 mm, and the positional deviation between the center O1 of the rod 8b and the center O2 of the nozzle is 0.02 mm. In this way, the positional deviation of the sealing member 8a relative to the nozzle 14a is 0.01 mm smaller than the positional deviation of the needle valve (rod 8b) relative to the nozzle 14a.

[0075] In Modification 1, the positional deviation between the center O3 of the sealing member 8a and the center O2 of the nozzle 14a is 0.01 mm, which is smaller than the positional deviation with respect to the nozzle 14a in the embodiment. Therefore, in Modification 1, when the sealing member 8a is in the open position, the side of the sealing member 8a where the center is offset from the nozzle center (the side where the sealing member 8a is spaced apart) is also spaced apart from the valve seat 14d, as shown in Fig. 14 .

[0076] FIG. 15 is a diagram illustrating the behavior of the tip of needle valve 8 in Modification 1 when needle valve 8 is moved from the open position to the closed position and then moved back to the open position. Figure 15(a) shows the needle valve 8 moving from the open position to the closed position, Figure 15(b) shows the needle valve 8 in the closed position, Figure 15(c) shows the needle valve 8 moving from the closed position to the open position, and Figure 15(d) shows the needle valve 8 in the open position.

[0077] As shown in FIG. 14, in this modification 1, when the sealing member 8a is in the open position, the offset side (left side in the figure) of the center of the sealing member 8a relative to the center of the nozzle 14a is also separated from the valve seat 14d. Therefore, in modification 1, when the sealing member 8a moves from the open position to the closed position, the offset side (left side in the figure) of the sealing member 8a abuts against the valve seat 14d. In this modification 1 as well, the sealing member 8a is elastically held to the rod 8b by the elastic member 30. Therefore, when the offset side of the sealing member 8a abuts against the valve seat 14d, the elastic member 30 elastically deforms and absorbs the impact. This makes it possible to effectively suppress deformation due to the impact.

[0078] After the misaligned side of the sealing member 8a hits the valve seat 14d, as in the embodiment, the rod 8b bends due to the reaction force of the valve seat 14d, tilting the tip side and descending while reducing the misalignment of the sealing member 8a with the nozzle 14a. As a result, as in the embodiment, the nozzle 14a is sealed with the center O3 of the sealing member 8a and the center O2 of the nozzle substantially aligned, as shown in Figure 15(b). In the first modification, the misalignment of the sealing member 8a with the nozzle is smaller than in the embodiment, so that the bending of the rod 8b is suppressed and the stress on the valve receiver 20 that receives the rod 8b can be reduced.

[0079] When moving from the sealing position to the open position, as in the embodiment, the restoring force of the bent rod 8b causes the sealing member 8a to move toward the misaligned side, and the side opposite to the misaligned side is opened first, as shown in Figure 15(c), which causes the liquid to flow out toward the nozzle 14a on the side opposite to the misaligned side (the right side in the figure).

[0080] In Modification 1, when the needle valve 8 further moves to the open position, the offset side (left side in the figure) of the sealing member 8a also moves away from the valve seat 14d. However, if the liquid is a thixotropic fluid such as paint, as described above, the liquid continues to flow from the point where it first started flowing into the nozzle 14a. Therefore, even if the offset side moves away from the valve seat 14d, almost no liquid flows into the nozzle 14a through the gap on the offset side. This stabilizes the curve of the liquid being discharged from the nozzle 14a.

[0081] On the other hand, even if the liquid has almost no thixotropy, it can be bent and ejected in a desired direction. This is because the gap on the misaligned side (left side in the figure) is narrower than the gap on the opposite side (right side in the figure). Therefore, as explained in Figures 8 and 9, the liquid can be bent and ejected in a desired direction by using differences in the flow speed and flow rate of the liquid flowing into the nozzle 14a. This makes it possible to suppress deviations in the landing positions between nozzles.

[0082] Furthermore, when the offset side (left side in the figure) of the sealing member 8a moves away from the valve seat 14d before moving to the open position, the reaction force from the valve seat 14d disappears, and the elastic member 30, which had been elastically deformed by the reaction force from the valve seat 14d, returns to its original state. As a result, the sealing member 8a vibrates slightly in the Y direction. If the liquid is a thixotropic fluid, this vibration of the sealing member 8a shears the liquid around the sealing member 8a, further reducing its viscosity. As a result, the liquid flows more easily into the nozzle 14a, which enables faster liquid ejection and improved responsiveness.

[0083] [Variation 2] Fig. 16 is a diagram illustrating Modification 2. Fig. 16 shows a state in which the needle valve 8 is in the open position where it opens the nozzle. In Modification 2, the positional deviation between the center O3 of the sealing member 8a and the center O2 of the nozzle 14a is further reduced compared to Modification 1. The positional deviation between the center O3 of the sealing member 8a and the center O2 of the nozzle 14a is 0.005 mm, and the positional deviation between the center O1 of the rod 8b and the center O2 of the nozzle is 0.02 mm.

[0084] In Modification 2, the displacement of the sealing member 8a relative to the nozzle 14a is slight. Therefore, as shown in Fig. 16, when the needle valve 8 is in the open position, the gap between the sealing member 8a and the valve seat 14d on the side where the center of the sealing member is displaced from the center of the nozzle (left side in the figure) is only slightly narrower than the gap between the sealing member 8a and the valve seat 14d on the side opposite to the displaced side (right side in the figure).

[0085] FIG. 17 is a diagram illustrating the behavior of the tip of the needle valve 8 when the needle valve 8 in the second modification is moved from the closed position to the open position. Figure 17(a) shows the needle valve 8 in the closed position, Figure 17(b) shows the needle valve 8 moving from the closed position to the open position, and Figure 17(c) shows the needle valve 8 in the open position.

[0086] 17(a), in Modification 2, the tip side of the rod 8b also tilts during sealing, so that the center O3 of the sealing member 8a and the center of the nozzle 14a are substantially aligned, thereby sealing the nozzle 14a. In Modification 2, the displacement of the sealing member 8a is slight, and therefore the tilt of the rod 8b is also slight.

[0087] When the needle valve 8 is moved from the closed position to the open position, as shown in FIG. 17(b), the side opposite the misaligned side of the sealing member 8a (the right side in the figure) separates before the misaligned side (the left side in the figure). This is because a strong clockwise moment acts on the rod 8b, whose central axis is tilted during sealing, when it is moved to the open position. In Variation 2, because the misalignment of the sealing member 8a with respect to the nozzle 14a is slight, the misaligned side of the sealing member 8a (the left side in the figure) also separates from the valve seat 14d immediately thereafter. However, if the liquid is a thixotropic fluid, the viscosity of the side opposite the misaligned side (the right side in the figure) that initially starts to flow toward the nozzle 14a decreases due to shear forces, making it easier to flow. Therefore, until the needle valve 8 moves to the open position to some extent and the gap between the sealing member 8a on the misaligned side (the left side in the figure) and the valve seat 14d widens to some extent, most of the liquid flows into the nozzle 14a from the side opposite the misaligned side (the right side in the figure). Therefore, as a result, the liquid ejected from the nozzle 14a can be bent in a desired direction.

[0088] In this way, if all sealing members 8a are misaligned in the same direction relative to the nozzles 14a even slightly, the liquid ejected from all nozzles 14a will bend in the same direction, and deviation in landing position between nozzles can be suppressed.

[0089] [Variation 3] FIG. 18 is a diagram illustrating the third modification. In this third modification, the nozzle 14a and the valve seat portion 14d move to align the center of the sealing member 8a with the center of the nozzle 14a during sealing.

[0090] As shown in Figure 18, the nozzle plate 14 is made up of a plate-shaped base member 141 and multiple nozzle members 142, each having a nozzle 14a and a valve seat 14d. The base member 141 has multiple stepped holes 141a, each consisting of a large-diameter portion 141a1 and a small-diameter portion 141a2, at locations facing each needle valve 8, and a nozzle member 142 is set in each stepped hole 141a. An elastic member 31 is provided in the gap between the nozzle member 142 and the stepped hole 141a, and the nozzle member 142 is elastically held relative to the base member 141. The elastic member 31 is provided by pouring a liquid or gel-like rubber or resin material into the gap between the nozzle member 142 and the stepped hole 141a and allowing it to harden.

[0091] The nozzle forming portion of the nozzle member 142 has an outer diameter of 0.6 mm, and the valve seat forming portion has an outer diameter of 3.0 mm. The large diameter portion 141a1 of the stepped hole portion 141a has an inner diameter of 3.4 mm and a depth of 0.5 mm, and the small diameter portion 141a2 has an inner diameter of 1.0 mm and a depth of 0.1 mm.

[0092] In this modification 3, the spherical sealing member 8a of the needle valve 8 is fixed by crimping to the tip of the rod 8b, but similarly to the above, it may be elastically held at the tip of the rod 8b by the elastic member 30. Also, the tip of the needle valve 8 (the tip of the rod 8b) may be machined into a spherical shape, and the sealing member 8a may be eliminated.

[0093] FIG. 19 is a diagram illustrating the behavior of the needle valve 8 in Modification 3 when it is moved from the open position to the closed position. FIG. 19(a) shows the needle valve 8 in the open position, and FIG. 19(b) shows the needle valve 8 in the closed position. As shown in FIG. 19(a), when the needle valve 8 is in the open position, the center O3 of the sealing member 8a, which is the tip of the needle valve 8, is offset from the center O2 of the nozzle 14a. When the needle valve 8 is lowered from the state shown in FIG. 19(a), the offset side (left side in the figure) of the sealing member 8a abuts against the valve seat 14d. When the needle valve 8 is further lowered in this abutting state, the valve seat 14d of the nozzle member 142 is pressed into the sealing member 8a. This causes the offset side (left side in the figure) of the elastic member 31 to elastically deform, and the nozzle member 142 moves toward the offset side (leftward in the figure, in the direction away from the center of the sealing member) as indicated by the arrow in FIG. 19(a). This causes the center O2 of the nozzle 14a and the center O3 of the sealing member 8a to approach each other. When the needle valve 8 is positioned in the sealed position, the centers of the nozzle 14a and the sealing member 8a substantially coincide with each other, as shown in FIG. 19(b). As a result, the nozzle 14a is also sealed well in the third modification.

[0094] When the needle valve 8 is moved from the closed position to the open position, the opposite operation to the above is performed. That is, as the needle valve 8 rises, the elastic force (restoring force) of the elastic member 31, which is elastically deformed on the misaligned side, moves the nozzle member 142 in the direction opposite to the misalignment direction of the sealing member (to the right in the figure). As a result, the side of the sealing member 8a opposite to the misalignment side (the right side in the figure) separates from the valve seat 14d, while the misalignment side (the left side in the figure) remains in contact with the valve seat 14d. Therefore, in Modification 3 as well, liquid can start flowing into the nozzle 14a from the side opposite to the misalignment side (the right side in the figure), and the liquid ejected from the nozzle 14a can be bent in the desired direction.

[0095] Also, in the configuration shown in Modification 3, the nozzle member 142 is elastically held to the base member 141 by the elastic member 31, so that the impact when the sealing member 8a hits the valve seat 14d when the needle valve 8 is lowered can be absorbed by the elastic member 31. Furthermore, the contact pressure when the sealing member 8a slides against the valve seat 14d when the needle valve 8 is raised and lowered can be reduced, and wear on the sealing member 8a and the valve seat 14d can be suppressed.

[0096] Furthermore, as with the embodiment, the needle valve 8 is preferably configured such that the sealing member 8a is elastically held on the rod 8b by the elastic member 30, which can further reduce the impact force and contact pressure.

[0097] Next, an example of a manufacturing method in which the tip portions (sealing members 8a) of all the needle valves 8 are shifted in the same direction relative to the nozzles 14a will be described. FIG. 20 is a diagram illustrating an example of a manufacturing method in this embodiment and modifications 1 and 2. In FIG. The flow path member 15 to which the nozzle plate 14 is positioned and attached has two positioning parts. One of the two positioning parts is for positioning the sealing member 8a so that the rod 8b and the sealing member 8a are misaligned to a desired position when the sealing member 8a is joined to the rod 8b. The other of the two positioning parts is a regular positioning part that positions the nozzle plate 14 so that the misalignment between the nozzle 14a and the tip of the needle valve (sealing member 8a) is the desired misalignment.

[0098] For example, a sealing member positioning hole as a sealing member positioning portion and a regular positioning hole as a regular positioning portion are provided in the flow path member 15. When joining the sealing member 8a to the rod 8b, a positioning pin is inserted into the sealing member positioning hole. Then, after joining the sealing member 8a, when officially positioning the nozzle plate 14 on the flow path member 15, a configuration can be considered in which the positioning pin is replaced from the sealing member positioning hole to the regular positioning hole.

[0099] First, with the nozzle plate 14 removed, the liquid ejection head 10 is set with the nozzle plate side facing upward, and ultraviolet curing rubber, which is a liquid or gel-like elastic material, is poured into the recesses 8b1 of the rods 8b of each needle valve 8, which are held so that they can move up and down. Next, sealing members 8a are inserted into the recesses 8b1 of each rod 8b into which the ultraviolet curing rubber has been poured. Alternatively, the ultraviolet curing rubber may be poured after the sealing members 8a are inserted into the recesses b1 of each rod.

[0100] Next, the nozzle plate 14 is attached to the flow path member 15. At this time, the nozzle plate 14 is positioned in the sealing member positioning portion of the flow path member 15 and attached to the flow path member 15. For example, when the center O1 of the rod 8b and the center O3 of the sealing member 8a are to be approximately aligned as in the embodiment, the nozzle plate 14 is positioned by the sealing member positioning portion so that the center O2 of the nozzle 14a is aligned with the center O3 of the rod 8b. On the other hand, when the center of the sealing member 8a is to be shifted by 0.01 m from the center of the rod 8b as in Modification 1, the nozzle plate 14 is positioned by the sealing member positioning portion so that the center O2 of the nozzle 14a is shifted by 0.01 mm from the center O3 of the rod 8b.

[0101] Next, as shown in FIG. 20(a), an ultraviolet irradiation fiber 50 is inserted into a flow path 5 that is not filled with liquid, and then, as shown in FIG. 20(b), each rod 8b (needle valve) is moved to the sealing position. As a result, the sealing member 8a moves within the recess 8b1, and the positional deviation between the rod 8b and the sealing member 8a becomes the desired positional deviation. Furthermore, for all needle valves 8, the center O3 of the sealing member 8a is shifted by the desired amount in the same direction relative to the center O1 of the rod 8b. Furthermore, by moving each rod 8b (needle valve) to the sealing position, the sealing member 8a comes into contact with the bottom surface of the recess 8b1.

[0102] In this state, as shown in Figure 20(c), ultraviolet light is irradiated from the ultraviolet irradiation fiber 50 toward the ultraviolet curing rubber, which is the elastic member, to cure the ultraviolet curing rubber. As a result, the sealing member 8a is joined to the rod 8b by the elastic member 30 and is elastically held on the rod. By joining the sealing member 8a while it is in the sealing position, the sealing member 8a can be joined in reliable contact with the bottom surface of the recess 8b1. After curing, as shown in FIG. 20(d), the rod 8b (needle valve 8) is moved to the open position, and then the ultraviolet irradiation fiber is removed from the liquid chamber.

[0103] Thereafter, the nozzle plate 14 is temporarily removed, positioned at a regular positioning portion of the flow path member 15, and then reattached to the flow path member 15. When the nozzle plate 14 is positioned at this regular positioning portion, the tip end (sealing member 8a) of each needle valve 8 is displaced by a desired amount in the X direction relative to the center of the nozzle 14a.

[0104] Alternatively, the nozzle plate 14 may be properly positioned by shifting it diagonally from the position determined by the sealing member positioning unit, so that the tip end (sealing member 8a) of each needle valve 8 is shifted to the same side in both the X and Y directions relative to the center of the nozzle 14a. This makes it possible to suppress deviations in the landing positions between nozzles in the X and Y directions.

[0105] In the manufacturing method shown in FIG. 20, the sealing members 8a of all the needle valves 8 can be joined with a desired amount of offset in the same direction relative to the rods 8b without using a special alignment device.

[0106] Furthermore, since all the sealing members 8a are joined to the rods 8b at the same time, the manufacturing takt time can be shortened and manufacturing costs can be reduced compared to when the sealing members 8a are joined to the rods 8b one by one.

[0107] FIG. 21 is a diagram illustrating an example of a manufacturing method in the third modification. First, the nozzle member 142 is set in the stepped hole 141a of the base member 141 of the nozzle plate 14, and ultraviolet curing rubber, which is a liquid or gel-like elastic member, is poured in. Alternatively, the nozzle member 142 may be set in the stepped hole 141a after the liquid or gel-like ultraviolet curing rubber has been poured into the stepped hole 141a.

[0108] 21(a), the nozzle plate 14 is attached to the liquid ejection head body by positioning it using the nozzle member positioning portion of the flow path member 15. As a result, the nozzle plate 14 is positioned on the flow path member 15 so that the center O1 of the nozzle 14a coincides with the center O2 of the rod 8b.

[0109] 21(b), after inserting the ultraviolet irradiation fiber 50 into the flow path 5 that is not filled with liquid, each needle valve 8 is moved to the sealing position. As a result, the nozzle member 142 moves inside the stepped hole portion 141a, and the nozzle member 142 is positioned on the base member 141 with the center O3 of the sealing member and the center O2 of the nozzle 14a aligned.

[0110] 21(c), ultraviolet light is irradiated from the ultraviolet irradiation fiber 50 onto the ultraviolet curing rubber, which is the elastic member, to cure the ultraviolet curing rubber. As a result, the nozzle member 142 is joined to the base member 141, and the nozzle member 142 is elastically held by the base member 141.

[0111] After the ultraviolet curing rubber has hardened, the needle valves 8 are moved to the open position, and then the ultraviolet irradiation fibers 50 are removed from the flow paths 5. Thereafter, the nozzle plate 14 is temporarily removed, positioned in the correct positioning portion of the flow path member 15, and then reattached to the flow path member 15. When the nozzle plate 14 is positioned in this correct positioning portion, the tip ends (sealing members 8a) of the needle valves are displaced by a desired amount in the same direction relative to the center of the nozzles 14a.

[0112] 21 also makes it possible to position and bond all of the nozzle members 142 to the desired positions relative to the base member 141 without using a special alignment device. Furthermore, because all of the nozzle members 142 are bonded to the base member 141 at the same time, the manufacturing takt time can be shortened compared to when the nozzle members 142 are bonded to the base member 141 one by one, and manufacturing costs can be reduced.

[0113] Furthermore, a thermoplastic elastomer may be used as the elastic member 31 that joins the nozzle member 142 to the base member 141. Because the nozzle plate 14 can come into contact with external components, it can be softened by heating it from the outside with a heater, allowing for alignment even during operation. Because it can be easily cooled from the outside, the elastic member 31 can be easily solidified in a short time.

[0114] Furthermore, in the above description, the sealing member 8a is spherical, but this is not limiting, and the sealing member 8a may have a conical tip as shown in Fig. 22. Fig. 22(a) is a diagram showing the embodiment, Modification 1, and Modification 2 in which a conical sealing member 8a is used, and Fig. 22(b) is a diagram showing Modification 3 in which a conical sealing member 8a is used.

[0115] 22, when a sealing member 8a with a conical tip is used, the tip is pointed, so it is preferable to make the valve seat 14d on the side opposite the nozzle 14a a curved surface (for example, a curved surface with an R of 0.3). With this configuration, when the sealing member 8a, which is misaligned with respect to the nozzle 14a, descends, the valve seat 14d can be brought into contact with the inclined surface of the sealing member 8a. This makes it possible to suppress wear and damage to the valve seat 14d.

[0116] Furthermore, in the embodiment, variant 1, and variant 2, the needle valve is composed of two members, a rod and a sealing member, and the sealing member is elastically held on the rod, but the tip of the needle valve may be machined into a spherical or conical shape, and the needle valve 8 may be composed of a single member.

[0117] Next, an example of a liquid ejection device having the above-described liquid ejection head 10 will be described.

[0118] FIG. 23 is a schematic perspective view of a device 100 for discharging liquid. The liquid discharging device 100 includes a movable frame unit 120 that is installed facing an object 200 to be discharged. The frame unit 120 includes a Y-axis rail 101 extending horizontally, a plurality of X-axis rails 102 extending vertically and provided at predetermined intervals, and a Z-axis rail 103 intersecting the X-axis rail 102 and the Y-axis rail 101.

[0119] Each X-axis rail 102 holds a Y-axis rail 101 extending horizontally so that the Y-axis rail 101 can move in the X direction (the direction in which the nozzles of the liquid ejection head are arranged, which is the vertical direction). Furthermore, the Y-axis rail 101 holds a Z-axis rail 103 so that the Z-axis rail 103 can move in the Y direction. The Z-axis rail 103 holds the carriage 110 so that the carriage 110 can move in the Z direction.

[0120] The carriage 110 is equipped with a head holder 130. The head holder 130 holds, for example, liquid ejection heads of different colors. For example, it holds a C-color liquid ejection head that ejects cyan paint, an M-color liquid ejection head that ejects magenta paint, a Y-color liquid ejection head that ejects yellow paint, and a K-color liquid ejection head that ejects black paint. It may also hold a W-color liquid ejection head that ejects white paint. It may also hold a liquid ejection head that ejects clear (transparent) coating paint, so that coating can be applied simultaneously with printing.

[0121] The carriage 110 is also provided with a first Z-direction driver 140a that moves the carriage 110 in the Z direction (the liquid ejection direction, which is the direction toward and away from the ejection target 200) along the Z-rail 103. It is also provided with a Y-direction driver 150 that moves the Z-rail 103 in the Y direction (the horizontal direction, which is perpendicular to both the liquid ejection direction and the nozzle arrangement direction of the liquid ejection head) along the Y-rail 101. It is also provided with an X-direction driver 160 that moves the Y-rail 101 in the X direction (the nozzle arrangement direction of the liquid ejection head, which is the vertical direction) along the X-rail 102. The Y-rails 101 are supported by the X-direction drivers 160 that are held by each Y-rail 101. It is also provided with a second Z-direction driver 140b that moves the head holder 130 in the Z direction relative to the carriage 110.

[0122] The liquid ejection device 100 ejects paint, an example of which is a liquid, from a liquid ejection head provided on a head holder 130 while moving a carriage 110 in the X-axis, Y-axis, and Z-axis directions, to draw on an object 200 onto which the liquid is to be ejected. Here, the movement of the carriage 110 and head holder 130 in the Z direction does not need to be parallel to the Z direction, and may be oblique movement as long as it includes at least a component in the Z direction. Furthermore, if the liquid ejection head has a single nozzle row, the liquid ejection head may be held on the carriage 110 so as to be tiltable with respect to the X-axis direction, making the nozzle pitch variable.

[0123] FIG. 24 is a diagram showing an example of a supply device 170 that supplies paint liquid to a plurality of liquid ejection heads 10 included in a device 100 that ejects liquid. The supply device 170 includes tanks 172a to 172d as sealed containers that contain paints 171a to 171d to be ejected from the liquid ejection heads 10a to 10d held by the head holder .

[0124] The tank 172 and the supply port 12 (see FIG. 1) of the liquid ejection head 10 are connected via a tube 173. Meanwhile, the tank 172 is connected to a compressor 176 via a pipe 175 including an air regulator 174. The compressor 176 supplies pressurized air to the tank 172. This puts the paint inside the liquid ejection head 10 into a pressurized state, and by opening the needle valve 8 described above, the paint is ejected from the nozzle 14a.

[0125] In Figure 23, the surface shape of the object 200 onto which the liquid is to be ejected is shown as a flat surface, but the surface shape of the object 200 onto which the liquid is to be ejected may also be a nearly vertical surface, such as the body of a car or truck, or the body of an airplane, or a surface with a large radius of curvature.

[0126] FIG. 25 is a diagram showing an example of an electrode manufacturing apparatus 700 as an apparatus for discharging liquid, which is equipped with the liquid discharge head of this embodiment. The electrode manufacturing apparatus 700 includes a discharge process section 710 that includes a process of applying a liquid composition to a printing substrate 704 having an object to be discharged to form a liquid composition layer, and a heating process section 730 that includes a heating process of heating the liquid composition layer to obtain an electrode mixture layer.

[0127] The printing substrate 704 on which the liquid composition layer is formed is not particularly limited as long as it is an object on which a layer having an electrode material is to be formed, and can be appropriately selected depending on the purpose. For example, an electrode substrate (current collector), an active material layer, a layer having a solid electrode material, etc. can be mentioned.

[0128] Furthermore, the discharge process unit 710 may be configured to form a layer having an electrode material by directly discharging a liquid composition, as long as it is possible to form a layer having an electrode material on the printing substrate 704. Alternatively, the discharge process unit 710 may be configured to form a layer having an electrode material by indirectly discharging a liquid composition. The heating process section 730 is a process for heating the liquid composition that has been discharged onto the printing substrate 704 in the discharge process section 710. The liquid composition layer can be dried by heating.

[0129] The electrode manufacturing apparatus 700 includes a conveying section 705 that conveys the printing substrate 704, and the conveying section 705 conveys the printing substrate 704 at a preset speed through the ejection process section 710 and the heating process section 730 in that order. There are no particular limitations on the method for manufacturing the printing substrate 704 having an object to be ejected, such as an active material layer, and any known method can be selected as appropriate. The ejection process section 710 includes a printing device 281a that includes the liquid ejection head 10 of this embodiment that ejects a liquid composition onto the printing substrate 704. The apparatus also includes a storage container 281b that stores the liquid composition, and a supply tube 281c that supplies the liquid composition stored in the storage container 281b to the printing device 281a.

[0130] The storage container 281b stores the liquid composition 707, and the discharge process unit 710 discharges the liquid composition 707 from the printing device 281a and applies the liquid composition 707 onto the printing substrate 704 to form a thin film of the liquid composition layer. The storage container 281b may be configured as an integral part of the manufacturing apparatus for the electrode mixture layer, or may be configured as a removable part from the manufacturing apparatus for the electrode mixture layer. Alternatively, the storage container 281b may be a container used for adding the liquid to a storage container integrated with the manufacturing apparatus for the electrode mixture layer or a storage container removable from the manufacturing apparatus for the electrode mixture layer. Furthermore, the storage container 281b and the supply tube 281c can be arbitrarily selected as long as they can stably store and supply the liquid composition 707.

[0131] The heating process section 730 has a heating device 703 and includes a solvent removal step of heating and drying and removing the solvent remaining in the liquid composition layer with the heating device 703. This allows the formation of an electrode mixture layer. The heating process section 730 may perform the solvent removal step under reduced pressure.

[0132] The heating device 703 is not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include a substrate heater, an IR heater, a hot air heater, etc., and these may be combined. The heating temperature and time can be appropriately selected depending on the boiling point of the solvent contained in the liquid composition 707 and the thickness of the formed film.

[0133] When the liquid ejection head 10 of this embodiment is used in the electrode manufacturing apparatus 700, the liquid composition can be ejected to a targeted location on an object to be ejected. The electrode mixture layer can be suitably used, for example, as part of the configuration of an electrochemical element. The components other than the electrode mixture layer in the electrochemical element are not particularly limited, and known components can be appropriately selected, such as a positive electrode, a negative electrode, and a separator.

[0134] Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and it goes without saying that various modifications can be made without departing from the spirit of the present invention.

[0135] In the above description, an embodiment has been described in which the drive control device 40 applies a voltage to a driver such as the piezoelectric element 2a to open and close the needle valve 8. However, the present invention is not limited to this, and the needle valve 8 may be opened and closed by air pressure or hydraulic pressure. In this case, the drive pulse generated by the drive control device 40 is a drive waveform for driving the air- or hydraulic-based pressurizing mechanism at a set pressure.

[0136] In this application, a "liquid ejection device" refers to a device that includes a liquid ejection head or a liquid ejection unit in which functional components and mechanisms are integrated with the liquid ejection head, and that ejects liquid by driving the liquid ejection head. The above-mentioned integration includes, for example, a device in which the liquid ejection head and the functional components or mechanisms are fixed to each other by fastening, bonding, engaging, etc., or a device in which one is held movably relative to the other. The liquid ejection head and the functional components or mechanisms may also be detachable from each other.

[0137] There are liquid ejection units in which the liquid ejection head and head tank are integrated, and in which the two are integrated by being connected to each other by a tube, etc. Here, it is also possible to add a unit including a filter between the liquid ejection head and head tank of these liquid ejection units.

[0138] There are liquid ejection units in which the liquid ejection head and carriage are integrated, and liquid ejection units in which the liquid ejection head, carriage, and scanning movement mechanism are integrated, and there are liquid ejection units in which the liquid ejection head is movably held by a guide member that constitutes part of the scanning movement mechanism, and the liquid ejection head and scanning movement mechanism are integrated.

[0139] Some liquid ejection units integrate the liquid ejection head, carriage, and maintenance and recovery mechanism by fixing a cap member, which is part of the maintenance and recovery mechanism, to a carriage on which the liquid ejection head is attached. Other liquid ejection units integrate the liquid ejection head and supply mechanism by connecting a tube to the liquid ejection head, which is equipped with a head tank or flow path components. Liquid from a liquid storage source is supplied to the liquid ejection head via this tube.

[0140] The scanning movement mechanism includes the guide member alone, and the supply mechanism includes the tube alone and the loading unit alone.

[0141] The term "device for ejecting liquid" includes not only a device that can eject liquid onto an object onto which the liquid can adhere, but also a device that ejects liquid into air or liquid.

[0142] This "liquid ejection device" can also include means for feeding, transporting, and discharging items onto which liquid can be attached, as well as pre-processing devices and post-processing devices.

[0143] For example, examples of "liquid ejecting devices" include image forming devices that eject ink to form images on paper, and three-dimensional modeling devices (three-dimensional modeling devices) that eject modeling liquid onto a powder layer formed from layers of powder in order to create a three-dimensional object (a three-dimensional model).

[0144] Furthermore, the term "liquid ejection device" is not limited to devices that use ejected liquid to visualize meaningful images such as letters and figures. For example, it also includes devices that form patterns that have no meaning in themselves, and devices that create three-dimensional images.

[0145] The above-mentioned "object onto which liquid can adhere" refers to the aforementioned object onto which liquid is ejected, and means an object onto which liquid can adhere at least temporarily, an object onto which the liquid adheres and sticks, an object onto which the liquid adheres and penetrates, etc. Specific examples include media such as paper, recording paper, film, and cloth, electronic circuit boards, electronic components such as piezoelectric elements, powder layers, organ models, and test cells, and unless otherwise specified, includes all objects onto which liquid can adhere.

[0146] The material of the "substance to which a liquid can adhere" may be any material to which a liquid can adhere, even temporarily, such as paper, thread, fiber, fabric, leather, metal, plastic, glass, wood, or ceramics.

[0147] Furthermore, the "liquid ejection device" may be a device in which a head unit and an object onto which the liquid can be attached move relatively, but is not limited to this. Specific examples include a serial type device in which the head unit moves, and a line type device in which the head unit does not move.

[0148] Other examples of "liquid ejecting devices" include treatment liquid application devices that eject treatment liquid onto paper to apply the treatment liquid to the surface of the paper for purposes such as modifying the surface of the paper, and spray granulation devices that spray a composition liquid in which raw materials are dispersed through a nozzle hole to granulate fine particles of the raw materials.

[0149] Although the preferred embodiments of the present invention have been described above, the present invention is not limited to such specific embodiments, and unless otherwise specifically limited in the above description, various modifications and variations are possible within the spirit and scope of the present invention as set forth in the claims.

[0150] Although the preferred embodiments of the present invention have been described above, the present invention is not limited to such specific embodiments, and unless otherwise specifically limited in the above description, various modifications and variations are possible within the spirit and scope of the present invention as set forth in the claims.

[0151] The above description is merely an example, and each of the following aspects provides unique effects. (Aspect 1) In a liquid ejection head having a nozzle plate 14 having a nozzle row in which a plurality of nozzles 14a that eject liquid are arranged, and valve members such as a plurality of needle valves 8 that are provided corresponding to each nozzle 14a and that open and close the corresponding nozzle 14a, when the valve members are positioned in an open position that opens the nozzles in at least one of the nozzle arrangement direction (X direction) when viewed from the liquid ejection direction (Z direction) and the orthogonal direction (Y direction) perpendicular to the nozzle arrangement direction, the tips of all the valve members (center O3 of the sealing member) are shifted to the same side relative to the center O2 of the nozzle. When the valve element is moved from the nozzle closed position to the open position and the tip of the valve element separates from the nozzle plate, liquid flows into the nozzle through the gap between the nozzle plate and the tip of the valve element, causing the liquid to be ejected from the nozzle. Because the tip of the valve element is misaligned with the nozzle when in the open position, regardless of the shape of the valve element tip, liquid flows more easily into the nozzle around the tip of the valve element on the side opposite the side where the center of the valve element tip is separated from the nozzle center than on the side opposite the separated side. For example, when the nozzle tip shape is conical or spherical, the gap between the nozzle plate and the nozzle tip surface on the side opposite the side where the center of the valve element tip is separated from the nozzle center is wider than on the side opposite the separated side. As a result, liquid flows more easily into the nozzle on the side opposite the side where the center of the valve element tip is separated. Furthermore, when the nozzle tip shape is flat, the distance from the gap between the nozzle plate and the nozzle tip surface on the side opposite the side where the center of the valve element tip is separated from the nozzle center is shorter than on the side opposite the separated side. Therefore, even when the nozzle tip shape is flat, liquid flows more easily into the nozzle on the side opposite the side where the center of the valve element tip is separated from the nozzle center. In this way, regardless of the shape of the nozzle tip, liquid tends to flow into the nozzle on the side opposite to the side where the center of the valve member is spaced from the center of the nozzle. This causes an uneven flow of liquid into the nozzle, resulting in a curved line in the liquid being ejected from the nozzle. It is difficult to perfectly align the center of the tip of the valve member with the center of the nozzle, and there is a risk that the direction in which the tip of the valve member is misaligned with respect to the nozzle will differ for each nozzle, which will cause the direction in which the liquid ejected from the nozzle bends to differ from nozzle to nozzle, resulting in a large deviation in the landing position between nozzles. In contrast, in the first embodiment, the tips of all the valve members are offset to the same side relative to the center of the nozzle in at least one of the arrangement direction (X direction) and the perpendicular direction (Y direction), so that the direction of curvature of the liquid ejected from each nozzle can be aligned in at least one of the arrangement direction (X direction) and the perpendicular direction (Y direction), thereby suppressing deviation in the landing position between the nozzles in at least one of the arrangement direction (X direction) and the perpendicular direction (Y direction).

[0152] (Aspect 2) In the first embodiment, in the nozzle arrangement direction (X direction), the tips of all valve members such as needle valves are shifted to the same side with respect to the center O2 of the nozzle 14a when they are in the open position. Generally, a liquid ejection head performs drawing by ejecting liquid from nozzles while moving in a direction perpendicular to the nozzle arrangement direction. Since deviations in the landing positions in the direction perpendicular to the nozzle arrangement direction can be eliminated by adjusting the liquid ejection timing of each nozzle, image quality is not affected in the perpendicular direction (Y direction) even if the deviations of the tip of the valve member relative to the center O2 of the nozzle 14a when it is in the open position are not in the same direction, and there is a large deviation in the landing positions between nozzles. On the other hand, deviations in the landing positions in the nozzle arrangement direction (X direction) cannot be eliminated by controlling the adjustment of the liquid ejection timing of each nozzle. Therefore, when the nozzles are positioned in the open position in the nozzle arrangement direction, the tip of the valve member, such as a needle valve, is shifted to the same side relative to the center O2 of the nozzle 14a, thereby suppressing deviation in the landing position between nozzles in the nozzle arrangement direction (X direction), thereby effectively suppressing degradation of image quality.

[0153] (Aspect 3) In the first embodiment, the tips of all valve members such as needle valves 8 are shifted to the same side relative to the center O2 of the nozzle 14a when in the open position in both the nozzle arrangement direction (X direction) and the perpendicular direction (Y direction). This makes it possible to suppress deviations in landing positions between nozzles in both the nozzle arrangement direction (X direction) and the orthogonal direction (Y direction).

[0154] (Aspect 4) In embodiments 1 to 3, the nozzle plate 14 is positioned so that the tips of all valve members, such as needle valves, are shifted to the same side relative to the center of the nozzles in at least one of the nozzle arrangement direction (X direction) and the perpendicular direction (Y direction). With this, when the valve members are positioned in an open position that opens the nozzles 14a, the tips of all the valve members can be shifted to the same side relative to the center of the nozzle in at least one of the nozzle arrangement direction (X direction) and the perpendicular direction (Y direction).

[0155] (Aspect 5) In any of aspects 1 to 4, when a valve member such as a needle valve 8 is positioned in a closed position that closes the nozzle 14a, the distance between the center of the tip of the valve member and the center of the nozzle 14a is shorter than the distance between the center of the tip of the valve member and the center of the nozzle when the valve member is positioned in an open position. As a result, as described in the embodiment, it is possible to prevent the contact pressure between the tip of a valve member such as a needle valve 8 and the nozzle plate 14 from becoming uneven, and it is possible to seal the nozzle well.

[0156] (Aspect 6) In embodiment 5, the nozzle plate 14 has a guide portion such as a valve seat portion 14d that communicates with the nozzle 14a and guides the tip of a valve member such as a needle valve 8 so that the center of the tip of the valve member approaches the center of the nozzle 14a when the valve member moves from an open position to a closed position. As a result, as described in the embodiment, when a valve member such as a needle valve 8 is positioned at a closed position that closes the nozzle 14a, the positional deviation of the tip of the valve member relative to the nozzle 14a can be made smaller than when the valve member is positioned at an open position.

[0157] (Aspect 7) In embodiment 6, a valve member such as a needle valve 8 has a sealing member 8a that seals the nozzle 14a and an axial member such as a rod 8b that holds the sealing member 8a and is configured to be movable in the liquid ejection direction, and the positional deviation of the tip of the axial member such as the rod 8b from the nozzle when it is in the closed position is smaller than the positional deviation from the nozzle when it is in the open position. According to this, when the sealing member 8a is guided by a guide portion such as the valve seat portion 14d when moving from the open position to the closed position, the shaft member such as the rod 8b bends and rotates, and the positional deviation of the tip of the shaft member from the nozzle when it is in the open position is reduced compared to when it is in the sealed position, so that the positional deviation of the tip of the valve member from the nozzle when it is in the open position can also be reduced. Furthermore, by configuring the valve member from two components, the shaft member and the sealing member, the shaft member can be made of a material that easily bends when the sealing member 8a is guided by a guide portion such as the valve seat portion 14d, and the sealing member can be made of a material that is harder and less prone to elastic deformation than the shaft member. By configuring the shaft member from a material that easily bends, the contact pressure of the sealing member against the guide portion can be reduced, and the lifespan of the guide portion and the sealing member can be suppressed. Furthermore, by using a material for the sealing member that is hard and less prone to elastic deformation, the nozzle can be sealed well even when the valve member is driven at high frequency.

[0158] (Aspect 8) In the seventh aspect, the positional deviation of the sealing member 8a relative to the nozzle 14a in the open position is smaller than the positional deviation of the shaft member such as the rod 8b relative to the nozzle 14a in the open position. As described in Modifications 1 and 2, this configuration allows the rod 8b or other shaft member to bend or rotate when the valve seat 14d or other guide member guides the tip of the valve member so that the center of the tip of the valve member approaches the center of the nozzle 14a. By making the positional deviation of the sealing member 8a relative to the nozzle 14a in the open position smaller than the positional deviation of the shaft member relative to the nozzle 14a in the open position, the amount of movement of the center of the tip of the valve member, caused by the guide member, toward the center of the nozzle 14a is reduced compared to when the positional deviation of the sealing member 8a relative to the nozzle 14a in the open position is greater than or equal to the positional deviation of the shaft member relative to the nozzle 14a in the open position. This reduces the bending and tilt of the rod when the needle valve 8 or other valve member is positioned in the sealing position. This also reduces the stress on the retaining member, such as the valve receiving portion 20, that retains the shaft member in the main body of the liquid ejection head. Furthermore, as explained in the embodiment, the contact pressure between the sealing member and the guide portion such as the valve seat portion when the valve member is opened or closed can be reduced, and wear on the guide portion and the sealing member can be suppressed. can.

[0159] (Aspect 9) In any of aspects 6 to 8, a member such as a needle valve 8 has a sealing member 8a that seals the nozzle 14a, and an axial member such as a rod 8b that holds the sealing member 8a and is configured to be movable in the liquid ejection direction, and the sealing member 8a is elastically held at the tip of the axial member. This allows the sealing member to move toward the nozzle relative to the shaft member when guided by a guide portion such as the valve seat portion 14d, thereby reducing the contact pressure of the sealing member with the guide portion. Furthermore, the vibration of the sealing member absorbs the impact of the guide portion on the sealing member when the valve member moves from the open position to the closed position. Furthermore, if the liquid to be ejected is thixotropic, the vibration of the sealing member when it separates from the guide portion when the valve member moves from the closed position to the open position can apply shear force to the liquid and reduce the viscosity of the liquid. This increases the amount of liquid flowing to the nozzle, thereby increasing the amount of liquid ejected.

[0160] (Aspect 10) In the ninth embodiment, the sealing member 8a is held by an axial member such as a rod 8b via an elastic member 30. According to this, as explained in the embodiment, the sealing member 8a can be elastically held by the elastic member 30 on the shaft member such as the rod 8b.

[0161] (Aspect 11) In any of aspects 1 to 10, the valve member such as the needle valve 8 has a sealing member 8a that seals the nozzle 14a and an axial member such as a rod 8b that holds the sealing member 8a and is configured to be movable in the liquid ejection direction, and the sealing member 8a contacts the tip of the axial member such as the rod 8b in the axial direction of the axial member. This allows the sealing member 8a to be positioned with high precision in the axial direction (Z direction) relative to the rod, as described in the embodiment, thereby suppressing fluctuations in the open position of the tip of the valve member and stabilizing the amount of liquid discharged from the nozzle.

[0162] (Aspect 12) In any of embodiments 6 to 11, the nozzle plate 14 comprises a base member 141 and a nozzle member 142 having a nozzle 14a and a guide portion such as a valve seat portion 14d, and the nozzle member 142 is elastically held by the base member 141. As explained in Modification 3, when the tip of a valve member such as needle valve 8 hits the guide portion during movement from the open position to the closed position, the nozzle member moves elastically relative to the base member, absorbing the impact of the impact. Also, when the tip of the valve member is being guided by the guide portion while moving to the closed position, the nozzle member 142 moves elastically relative to the base member, reducing the contact pressure between the tip of the valve member and the guide portion. This reduces wear and damage to the tip of the valve member and the guide portion.

[0163] (Aspect 13) In the twelfth embodiment, the nozzle member 142 is held by the base member 141 via the elastic member 31 . According to this, as explained in the third modification, the nozzle member 142 can be elastically held to the base member by the elastic member 31.

[0164] (Aspect 14) In a liquid ejection device equipped with a liquid ejection head 10, any of the liquid ejection heads according to the first to twelfth embodiments was used as the liquid ejection head 10. This makes it possible to suppress deviations in landing positions between nozzles.

[0165] (Aspect 15) In a method for manufacturing a liquid ejection head including a nozzle plate 14 having a nozzle row in which a plurality of nozzles 14a that eject liquid are arranged, and valve members such as a plurality of needle valves 8 that are provided corresponding to each nozzle 14a and that open and close the corresponding nozzles 14a, the plurality of valve members have sealing members 8a that seal the nozzles 14a, and an axial member such as a rod 8b that holds the sealing members 8a and is configured to be movable in the liquid ejection direction, the method includes the steps of applying a fluid bonding agent to the tip of the axial member and placing the sealing member 8a on the tip of the axial member, moving the valve member to a closed position that closes the nozzles 14a and hardening the bonding agent, moving the valve member to an open position that opens the nozzles 14a, and positioning and attaching the nozzle plate 14 so that the tip of the valve member is misaligned with the nozzles 14a. According to this, as explained with reference to FIG. 20, the tips of all the valve members can be displaced in the same direction relative to the center of the nozzle.

[0166] (Aspect 16) In a method for manufacturing a liquid ejection head including a nozzle plate 14 having a nozzle row in which a plurality of nozzles 14a that eject liquid are arranged, and valve members such as a plurality of needle valves 8 that are provided corresponding to each nozzle 14a and that open and close the corresponding nozzles 14a, the nozzle plate 14 has a base member 141 and a plurality of nozzle members 142 having nozzles 14a arranged in holes such as a plurality of stepped holes 141a provided in positions of the base member 141 facing the valve members, the method includes the steps of applying a fluid bonding agent between each nozzle member 142 and the hole portion of the base member 141, moving the valve member to a closed position that closes the nozzles 14a and hardening the bonding agent, moving the valve member to an open position that opens the nozzles, and positioning and attaching the nozzle plate so that the tips of the valve members are misaligned with the nozzles 14a. According to this, as explained with reference to FIG. 21, the tips of all the valve members can be displaced in the same direction relative to the center of the nozzle. [Explanation of symbols]

[0167] 1: Liquid dispensing module 2: Actuator 2a: Piezoelectric element 2b: Fixed element 3: Arm member 5: Flow path 6: Movement mechanism 7: Compression spring 8: Needle valve 8a: Sealing member 8b: Rod 8b1: Recess 8c: Arm support 10: Liquid ejection head 11: Cover 11a: Storage section 11b:Valve through hole 12: Supply port 13: Discharge port 14: Nozzle plate 14a: Nozzle 14d:Valve seat part 15: Flow path member 16: Harness hole 17: Fixing member 18: Spring support plate 19: Sealing material 20: Valve receiving part 30: Elastic member 31: Elastic member 50: UV irradiation fiber 141: Base member 141a: Stepped hole 141a1: Large diameter section 141a2: Small diameter part 142: Nozzle member 700: Electrode manufacturing equipment 1422: Nozzle member O1: Center of needle valve (rod) O2: Center of nozzle O3: Center of sealing material n: needle valve [Prior art documents] [Patent documents]

[0168] [Patent Document 1] Japanese Patent Application Publication No. 2023-149916

Claims

1. a nozzle plate having a nozzle row in which a plurality of nozzles that eject liquid are arranged; A liquid ejection head having a plurality of valve members provided corresponding to each nozzle and opening and closing the corresponding nozzle, A liquid ejection head characterized in that, when the valve members are positioned in an open position that opens the nozzles, the tips of all of the valve members are shifted to the same side relative to the center of the nozzle in at least one direction of a nozzle arrangement direction when viewed from the liquid ejection direction and an orthogonal direction perpendicular to the nozzle arrangement direction.

2. 2. The liquid ejection head according to claim 1, A liquid ejection head, characterized in that, in the nozzle arrangement direction, the tips of all of the valve members are shifted to the same side with respect to the center of the nozzle when the valve members are in the open position.

3. 2. The liquid ejection head according to claim 1, A liquid ejection head characterized in that the tips of all valve members are shifted to the same side with respect to the center of the nozzle when positioned at the open position in both the nozzle arrangement direction and the perpendicular direction.

4. 2. The liquid ejection head according to claim 1, The liquid ejection head is characterized in that the nozzle plate is positioned so that the tips of all the valve members are shifted to the same side with respect to the center of the nozzle in at least one of the nozzle arrangement direction and the perpendicular direction.

5. 2. The liquid ejection head according to claim 1, A liquid ejection head characterized in that the distance between the center of the tip of the valve member and the center of the nozzle when the valve member is in a closed position that closes the nozzle is shorter than the distance between the center of the tip of the valve member and the center of the nozzle when the valve member is in the open position.

6. 6. The liquid ejection head according to claim 5, A liquid ejection head characterized in that the nozzle plate is connected to the nozzle and has a guide portion that guides the tip of the valve member so that the center of the tip of the valve member approaches the center of the nozzle when the valve member moves from the open position to the closed position.

7. 7. The liquid ejection head according to claim 6, the valve member has a sealing member that seals the nozzle, and a shaft member that holds the sealing member and is configured to be movable in a liquid ejection direction, A liquid ejection head, characterized in that the positional deviation of the tip of the shaft member from the nozzle when it is in the closed position is smaller than the positional deviation of the tip of the shaft member from the nozzle when it is in the open position.

8. 8. The liquid ejection head according to claim 7, A liquid ejection head, characterized in that a positional deviation of the sealing member with respect to the nozzle in the open position is smaller than a positional deviation of the shaft member with respect to the nozzle in the open position.

9. 7. The liquid ejection head according to claim 6, the valve member has a sealing member that seals the nozzle, and a shaft member that holds the sealing member and is configured to be movable in a liquid ejection direction, The liquid ejection head is characterized in that the sealing member is elastically held at the tip of the shaft member.

10. 10. The liquid ejection head according to claim 9, The liquid ejection head is characterized in that the sealing member is held by the shaft member via an elastic member.

11. 2. The liquid ejection head according to claim 1, the valve member has a sealing member that seals the nozzle, and a shaft member that holds the sealing member and is configured to be movable in a liquid ejection direction, The liquid ejection head is characterized in that the sealing member is in contact with the tip of the shaft member in the axial direction of the shaft member.

12. 7. The liquid ejection head according to claim 6, The nozzle plate comprises a base member and a plurality of nozzle members each having the nozzle and the guide portion, and the plurality of nozzle members are elastically held by the base member.

13. 13. The liquid ejection head according to claim 12, The liquid ejection head is characterized in that the nozzle member is held by the base member via an elastic member.

14. In a liquid ejection device equipped with a liquid ejection head, 10. A liquid ejection device, comprising: a liquid ejection head according to claim 1;

15. A method for manufacturing a liquid ejection head including a nozzle plate having a nozzle row in which a plurality of nozzles for ejecting liquid are arranged, and a plurality of valve members provided corresponding to each nozzle and for opening and closing the corresponding nozzle, comprising: the plurality of valve members each include a sealing member that seals the nozzle, and a shaft member that holds the sealing member and is configured to be movable in the liquid ejection direction; applying a fluid bonding agent to the tip of the shaft member and disposing the sealing member on the tip of the shaft member; moving the valve member to a closed position that closes the nozzle and hardens the bonding agent; moving the valve member to an open position to open the nozzle; and positioning and attaching the nozzle plate so that the tip of the valve member is misaligned with respect to the nozzle.

16. A method for manufacturing a liquid ejection head including a nozzle plate having a nozzle row in which a plurality of nozzles for ejecting liquid are arranged, and a plurality of valve members provided corresponding to each nozzle and for opening and closing the corresponding nozzle, comprising: the nozzle plate includes a base member and a plurality of nozzle members each having the nozzle disposed in a plurality of holes formed in the base member at a position facing the valve member; applying a flowable bonding agent between each nozzle member and the hole in the base member; moving the valve member to a closed position that closes the nozzle and hardens the bonding agent; moving the valve member to an open position to open the nozzle; and positioning and attaching the nozzle plate so that the tip of the valve member is misaligned with respect to the nozzle.

Images