Droplet ejection head and droplet ejection device

Abstract

To provide a droplet discharge head and a droplet discharge device which can reduce pressure loss when a liquid passes through a filter without increasing the size of a head in a horizontal direction.SOLUTION: A droplet discharge head 30 has a discharge flow passage 42 for passing a liquid discharged from a head part 50, wherein the discharge flow passage 42 includes an out filter chamber 422 provided with an out filter F2; the out filter chamber 422 includes a liquid inflow port 4221 to which the liquid discharged from the head part 50 flows, and a liquid outflow port 4222 to which the liquid in the out filter chamber 422 flows out; the out filter F2 is provided so as to divide the out filter chamber 422 into two chambers of a front chamber 422A including the liquid inflow port 4221 and a rear chamber 422B including the liquid outflow port 4222; and the front chamber 422A has a cross-sectional area H on a horizontal plane at the upper end larger than the area of the opening of the liquid inflow port 4221.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a droplet ejection head and a droplet ejection device. [Background technology]

[0002] Conventionally, in a droplet ejection head, in order to prevent ejection defects caused by foreign matter or air bubbles mixed in the ejected liquid, filters are provided on both the inlet and outlet sides of the liquid flow path so that foreign matter and air bubbles can be discharged (see, for example, Patent Documents 1 and 2). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 5531872 [Patent Document 2] Patent No. 5774047 Summary of the Invention [Problem to be solved by the invention]

[0004] A common method for passing liquid through the inside of such a droplet ejection head is to provide a pressure difference between the upstream and downstream sides of the liquid flow path, and therefore it is preferable to prevent the pressure difference from being reduced by reducing the pressure loss when the liquid passes through the filter.

[0005] However, in the invention of Patent Document 1, the filter on the outlet side is provided in the flow path so as to be parallel to the nozzle surface, and therefore, if the area of ​​the filter is increased in order to reduce pressure loss, the head itself becomes larger in the horizontal direction, which causes problems such as difficulty in connecting the joints when multiple heads are arranged side by side and an increase in the size of the carriage.

[0006] On the other hand, in the invention of Patent Document 2, the filter is provided vertically from the nozzle surface, so the area of ​​the filter can be increased without increasing the size of the head horizontally. However, because the chamber in which the filter is located is shaped parallel to the vertical direction or is shaped to taper upward, flow resistance occurs, and the difference in liquid flow rate between the top and bottom of the filter is likely to become large, which causes a problem that pressure loss is likely to occur when the liquid passes through the filter.

[0007] The present invention has been made in consideration of these circumstances, and its purpose is to provide a droplet ejection head and a droplet ejection device that can reduce the pressure loss when liquid passes through a filter without increasing the size of the head horizontally. [Means for solving the problem]

[0008] The invention described in claim 1 is A head portion provided with a nozzle for ejecting droplets; A supply flow path that supplies liquid to the head portion; a discharge flow path through which liquid discharged from the head portion passes, the discharge flow path includes an out-filter chamber provided with an out-filter that captures foreign matter contained in the liquid discharged from the head portion, the out-filter chamber includes a liquid inlet through which liquid discharged from the head portion flows in, and a liquid outlet through which liquid in the out-filter chamber flows out, the out-filter is provided in contact with an upper inner wall portion and a lower inner wall portion of the out-filter chamber so as to divide the out-filter chamber into two chambers, a front chamber including the liquid inlet and a rear chamber including the liquid outlet, The front chamber is characterized in that the cross-sectional area in a horizontal plane at the upper end is larger than the area of ​​the opening of the liquid inlet.

[0009] The invention described in claim 2 is the droplet ejection head described in claim 1, The liquid supply device is characterized by comprising a circulation flow path that circulates the liquid passing through the discharge flow path to the supply flow path.

[0010] The invention described in claim 3 is the droplet ejection head described in claim 1 or 2, The supply flow passage is characterized by including an in-filter that captures foreign matter contained in the liquid supplied to the head portion.

[0011] The invention described in claim 4 is the droplet ejection head described in claim 3, The diameter of the nozzle is equal to or larger than the diameter of the mesh of the outfilter, The mesh diameter of the out-filter is larger than or equal to the mesh diameter of the in-filter.

[0012] The invention described in claim 5 is the droplet ejection head described in claim 3 or 4, The area of ​​the in-filter is larger than the area of ​​the out-filter.

[0013] The invention described in claim 6 is the droplet ejection head described in any one of claims 1 to 5, the out-filter is provided substantially perpendicular to the nozzle surface, The front chamber is characterized in that an opposing surface facing the out-filter has a shape in which the distance between the front chamber and the out-filter increases from the lower end toward the upper end.

[0014] The invention described in claim 7 is the droplet ejection head described in any one of claims 1 to 5, the front chamber has a surface facing the out-filter that is substantially perpendicular to the nozzle surface, The out-filter is inclined at a predetermined angle with respect to the nozzle surface in a direction away from the opposing surface.

[0015] The invention described in claim 8 is the droplet ejection head described in any one of claims 1 to 7, The flow rate of the liquid passing through the out-filter is 50 ml / min or more and 160 ml / min or less.

[0016] The invention described in claim 9 is the droplet ejection head described in any one of claims 1 to 8, The viscosity of the droplets ejected from the nozzle is 5 cp or more and 15 cp or less.

[0017] The invention described in claim 10 is a droplet ejection device, The present invention is characterized by comprising a droplet ejection head according to any one of claims 1 to 9. Effect of the Invention

[0018] According to the present invention, it is possible to provide a droplet ejection head and a droplet ejection device that can reduce the pressure loss when liquid passes through a filter, without increasing the size of the head in the horizontal direction. [Brief description of the drawings]

[0019] [Figure 1] 1 is a perspective view showing the appearance of an inkjet recording apparatus according to an embodiment of the present invention; [Diagram 2] FIG. 2 is a front view showing the internal structure of a head unit according to an embodiment of the present invention. [Diagram 3] 1 is a front view showing an internal structure of an inkjet head according to an embodiment of the present invention; [Figure 4] FIG. 2 is an enlarged front view of an out-filter chamber according to one embodiment of the present invention. [Figure 5A] FIG. 13 is an enlarged front view showing a modified example of the opposing surface. [Figure 5B] FIG. 13 is an enlarged front view showing a modified example of the opposing surface. [Figure 5C] FIG. 13 is an enlarged front view showing a modified example of the opposing surface. [Figure 6A] FIG. 13 is an enlarged front view showing a modified example of the out-filter. [Figure 6B]FIG. 13 is an enlarged front view showing a modified example of the out-filter. [Figure 7] 13 is an enlarged front view showing a modified example of the opposing surface and the out-filter. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. However, the scope of the invention is not limited to the illustrated examples. In the following description, the same reference numerals are used to designate components having the same functions and configurations, and the description thereof will be omitted.

[0021] In the following description, the short side direction of the inkjet head 30 is defined as the X direction, the long side direction as the Y direction, and the direction perpendicular to the X and Y directions and in which ink is ejected from the inkjet head 30 as the Z direction. The upper end will be described as the highest position in the +Z direction (maximum Z coordinate), and the lower end will be described as the lowest position in the +Z direction (minimum Z coordinate).

[0022] [Inkjet recording device] First, as a droplet ejection device according to the present embodiment, a configuration example of an inkjet recording device 1 including an inkjet head 30 that is a droplet ejection head will be disclosed. FIG. 1 is a diagram showing a schematic configuration of an inkjet recording apparatus 1 according to an embodiment of the present invention. The inkjet recording apparatus 1 includes a transport section 10, a head unit 20, and the like.

[0023] [Transportation section] The transport unit 10 includes a ring-shaped transport belt 12 whose inner side is supported by two transport rollers 11, 11 that rotate around a rotation axis extending in the X-axis direction in Fig. 1. In the transport unit 10, with a recording medium M placed on the transport surface of the transport belt 12, the transport rollers 11 rotate in response to the operation of a transport motor (not shown), causing the transport belt 12 to move in a circular motion, thereby transporting the recording medium M in the movement direction (X direction) of the transport belt 12.

[0024] [Recording medium] The recording medium M is a sheet of paper or a long sheet material cut to a certain size. The recording medium M is supplied onto the conveyor belt 12 by a supply device (not shown), and after an image is recorded by ejecting ink, which is the liquid to be ejected, from the head unit 20, the recording medium M is ejected from the conveyor belt 12 to a predetermined ejection section. As the recording medium M, in addition to paper such as plain paper or coated paper, various media capable of fixing the ink that has landed on the surface, such as fabric or sheet-like resin, can be used.

[0025] [Head unit] FIG. 2 is a diagram showing the internal configuration of the head unit 20. As shown in FIG. In the inkjet recording device 1 of this embodiment, four head units 20 corresponding to four colors of ink, yellow (Y), magenta (M), cyan (C), and black (K), are arranged at predetermined intervals in the order of colors Y, M, C, and K from the upstream side in the transport direction of the recording medium M. Each head unit 20 has a plurality of inkjet heads 30 as droplet ejection heads that eject ink, and ejects ink at appropriate timing based on image data onto the recording medium M transported by the transport unit 10 to record an image. The number of head units 20 may be three or less, or five or more.

[0026] [Inkjet head] FIG. 3 is a schematic diagram showing a cross section of an ink flow path inside one inkjet head 30, as viewed from the front (X direction). The inkjet head 30 includes a liquid storage tank 40 and a head unit 50, and stores ink supplied from the outside in the liquid storage tank 40. The ink is then supplied to the head unit 50, and the ink is ejected from nozzles N provided on a nozzle surface 5221, which is the lower surface side (-Z direction side) of the head unit 50.

[0027] (Liquid storage tank) The liquid storage tank 40 is a box that stores ink therein. The liquid storage tank 40 includes a supply flow path 41 and a discharge flow path 42, and the lower surface of the liquid storage tank 40 is attached to the upper portion of the head unit 50 (+Z direction).

[0028] {Supply Channel} The supply flow path 41 is a flow path that supplies ink flowing in from an external ink tank (not shown) or the like to the head unit 50. The supply flow path 41 includes, in order from the top (+Z direction), an inlet 411, an in-filter chamber 412, and an outlet 413.

[0029] {Discharge flow path} The discharge flow path 42 is a flow path that discharges ink discharged from the head unit 50 from the inkjet head 30. The discharge flow path 42 includes, in order from above (in the +Z direction), an outlet 421, an out-filter chamber 422, an inlet 423, and the like. The in-filter chamber 412 and the discharge flow path 42 are connected by a deaeration path 43.

[0030] {Inlet / Outlet} The inlet 411 is an inlet through which ink is supplied from an external ink tank or the like into the inkjet head 30. The outlet 421 is an outlet through which ink is discharged from the head unit 50.

[0031] The inlet 411 and the outlet 421 are connected to an external ink tank via, for example, a tube (not shown) and a pump (not shown). When the inkjet head 30 is in use, the supply flow path 41 side is made to have a positive pressure by, for example, the pump, and a pressure difference is provided between the supply flow path 41 side and the discharge flow path 42 side, so that ink is circulated and supplied between the ink tank and the inkjet head 30.

[0032] The inkjet head 30 is not limited to a configuration in which ink circulates between an ink tank (not shown) and the inkjet head 30. For example, the outlet 421 may not be connected to an ink tank, and ink may be discharged from the outlet 421 to the outside of the inkjet head 30.

[0033] As a method for providing a pressure difference between the supply flow path 41 side and the discharge flow path 42 side, the supply flow path 41 side may be made to have a positive pressure by utilizing the head pressure with the ink tank. Also, the method is not limited to making the supply flow path 41 side a positive pressure, and for example, the discharge flow path 42 side may be made to have a negative pressure by connecting to a vacuum pump.

[0034] 2 and 3, the inlet 411 and the outlet 421 are provided at the upper end of the inkjet head 30, but the present invention is not limited to this. 3, the heights of the inlet 411 and the outlet 421 are the same, but this is not limited thereto. For example, the outlet 421 may be provided higher than the inlet 411, in which case air bubbles will flow more easily into the outlet 421 due to buoyancy.

[0035] {In-filter chamber} The in-filter chamber 412 is a container that stores the ink that has flowed in from the inlet 411, and includes an in-filter F1 that filters the ink.

[0036] <In-filter> The in-filter F1 is formed of, for example, a mesh-like porous metal or resin body, and has meshes of a predetermined size. The in-filter F1 is adhered by means of heat fusion or the like to the inner wall of the in-filter chamber 412 so as to be approximately parallel to the nozzle surface 5221, and divides the in-filter chamber 412 into an upstream in-filter chamber 412A and a downstream in-filter chamber 412B.

[0037] It is preferable to make the ratio of the area of ​​the in-filter F1 in the direction parallel to the XY directions to the area of ​​the inkjet head 30 in the direction parallel to the XY directions as large as possible. Normally, when ink is ejected from the nozzle N, the amount of ink passing through the in-filter F1 per unit area increases, which increases the pressure loss when the ink passes through the in-filter F1. As a result, the negative pressure applied to the nozzle N increases, and the ink ejection performance decreases. On the other hand, if the area of ​​the in-filter F1 in the direction parallel to the XY direction is increased, the amount of ink passing through the in-filter F1 per unit area is less likely to increase, which reduces the pressure loss when the ink passes through the in-filter F1, and reduces the effect on the ink ejection performance.

[0038] {Ventilator} The deaeration passage 43 is a passage that connects the upstream in-filter chamber 412A and the discharge passage . The air bubbles captured by the in-filter F1 and remaining in the upstream in-filter chamber 412A pass through the deaeration passage 43 and the exhaust passage 42, and are exhausted from the outlet 421.

[0039] {outlet, inlet} The outlet 413 and the inlet 423 are both provided at the lower end of the liquid storage tank 40 and communicate with the opening of the head portion 50 . By providing the outlet 413 and the inlet 423, it is possible to allow ink to flow in and out between the liquid storage tank 40 and the head unit 50.

[0040] {Out filter chamber} FIG. 4 is an enlarged cross-sectional view of the out-filter chamber 422 as viewed from the front (X direction). The out-filter chamber 422 is a space that filters the ink that flows in from the head portion 50 and is discharged from the outlet 421 .

[0041] Specifically, the out-filter chamber 422 comprises a liquid inlet 4221 provided at the lower end of the out-filter chamber 422, a liquid outlet 4222 provided at the upper end of the out-filter chamber 422, and an out-filter F2 that filters ink that flows into the out-filter chamber 422 from the liquid inlet 4221.

[0042] <Out Filter> The out-filter F2, like the in-filter F1, is formed of, for example, a mesh-like porous metal or resin, and has a mesh of a predetermined size. The out-filter F2 is bonded by means of heat fusion or the like so as to abut against the upper and lower ends of the inner wall of the out-filter chamber 422 and extend in the vertical direction (Z direction), dividing the out-filter chamber 422 into a front chamber 422A and a rear chamber 422B.

[0043] By providing the outfilter F2 in the discharge flow path 42 of the inkjet head 30, it is possible to prevent foreign matter from mixing with the ink discharged from the head unit 50 and returned to an external ink tank. In addition, even when the ink flows backward in the discharge flow path 42, it is possible to prevent foreign matter from mixing with the ink ejected from the nozzles N. It is also possible to prevent foreign matter from mixing with the inside when installing or replacing the inkjet head 30.

[0044] It is preferable that the out-filter F2 has an area smaller than that of the in-filter F1. As described above, if the pressure loss when the liquid passes through the in-filter F1 is large, the ejection performance of the nozzle N will decrease, so it is necessary to suppress this by increasing the area of ​​the in-filter F1. On the other hand, even if the area of ​​the out-filter F2 is reduced and the pressure loss when the liquid passes through the out-filter F2 increases, if the negative pressure at the outlet 421 is increased, the pressure difference between the supply flow path 41 side and the discharge flow path 42 side is maintained, and the ejection performance of the nozzle N will not be affected.

[0045] However, increasing the negative pressure at the outlet 421 places increased demands on the inkjet recording apparatus 1. For this reason, it is preferable to minimize the pressure loss when the liquid passes through the out-filter F2.

[0046] Therefore, it is preferable to arrange the out-filter F2 so that it extends in the vertical direction (Z direction) in this manner, because this reduces the pressure loss when the ink passes through the out-filter F2, and therefore the area of ​​the inkjet head 30 is less likely to become large in the horizontal direction even if the area of ​​the out-filter F2 is increased.

[0047] Furthermore, the out-filter F2 in this embodiment is attached to the out-filter chamber 422 so that the front chamber 422A includes a liquid inlet 4221 and the rear chamber 422B includes a liquid outlet 4222, and the cross-sectional area H in the XY plane at the upper end of the front chamber 422A is larger than the area of ​​the opening of the liquid inlet 4221.

[0048] The effect of providing the out-filter F2 in this manner will be described. When the cross-sectional area H of the upper end of front chamber 422A is larger than the area of ​​the opening of liquid inlet 4221, the flow resistance of front chamber 422A is reduced. Therefore, when ink flows into front chamber 422A from liquid inlet 4221, the flow rate of the ink is less likely to decrease, and the ink easily reaches the upper end of front chamber 422A. That is, the difference in the liquid flow rate between the upper and lower portions of the out-filter F2 is less likely to occur, and the pressure loss when the liquid passes through the out-filter F2 can be reduced.

[0049] Although the liquid discharged from the droplet discharge device 1 according to this embodiment is not limited to ink, the flow rate of the ink passing through the out-filter F2 is preferably 50 ml / min to 160 ml / min, and the viscosity of the ink is preferably 5 cp to 15 cp.

[0050] (Head section) Returning to FIG. 3, the head unit 50 will be described. The head unit 50 includes, for example, from the top (+Z direction), a storage chamber (manifold) 51, a wiring board (not shown), an FPC (Flexible Printed Circuit: flexible board (not shown)) connected to an end of the wiring board and equipped with a drive circuit for controlling ejection, and a head chip 52.

[0051] {Storage chamber} The storage chamber 51 is made of a synthetic resin material or the like, and is formed in a horizontally elongated box shape extending in the Y direction. At least two openings are provided at the upper end of the storage chamber 51. One opening communicates with the supply flow path 41 via an outlet 413, and ink transferred from the liquid storage tank 40 is stored in the storage chamber 51. The other opening communicates with the discharge flow path 42 via an inlet 423, and ink in the storage chamber 51 is discharged from an outlet 421.

[0052] {head tip} The head chip 52 includes a pressure chamber substrate 521 and a nozzle substrate 522 in this order from the top (+Z direction). A plurality of channels C are formed as pressure chambers penetrating in the Z direction in the pressure chamber substrate 521. In addition, a plurality of nozzles N openings, each consisting of a through hole extending along the Z direction, are formed in a staggered pattern on a nozzle surface 5221, which is the bottom surface side (-Z direction side) of the nozzle substrate 522.

[0053] In a state in which the nozzle substrate 522 is joined to the bottom surface side (-Z direction side) of the pressure chamber substrate 521, each channel C is provided so as to communicate with each nozzle N of the nozzle substrate 522. That is, the ink in the storage chamber 51 is sent to each nozzle N via each channel C. By applying a drive signal through wiring electrodes formed on the wiring board and the flexible board, a pressure change is imparted to the ink supplied to the channel C, causing the ink to be ejected from the nozzle N.

[0054] {Individual discharge path, common discharge path} Furthermore, between the channel C and the nozzle N (before the opening of the nozzle N), individual discharge paths 53 branch off, and each of these multiple individual discharge paths 53 communicates with one common discharge path 54. The common discharge path 54 bends upward (in the +Z direction) at the end of the head portion 50 on the discharge flow path 42 side, and communicates with a flow path connecting the inlet 423 and the out-filter chamber 422.

[0055] Of the ink supplied to the channel C, a portion of the ink that has not been discharged from the nozzle N is discharged from the outlet 421 via the individual discharge path 53 and the common discharge path 54. By refluxing the ink in this way, it is possible to suppress the settling of various particles contained in the ink, and it is also possible to expel foreign matter and air bubbles in the channel C and nozzle N to the outside together with the ink.

[0056] Similarly, a portion of the ink that has not been sent from the storage chamber 51 to the head chip 52 passes through another opening of the storage chamber 51 and the discharge flow path 42 and is discharged to the outside from the outlet 421 . In this case, the two openings of the storage chamber 51, which communicate with the outlet 413 and the inlet 423 of the liquid storage tank 40, are preferably disposed at both ends in the Y direction of the upper end of the storage chamber 51. In this way, when ink supplied from the outlet 413 is discharged to the inlet 423, the ink flows throughout the entire storage chamber 51. As a result, it becomes difficult for a portion where ink stagnates to be formed in the storage chamber 51, and air bubbles in the ink can be efficiently removed.

[0057] 3, the nozzle N has a substantially rectangular cross section, but this is not limited thereto. For example, the nozzle N may have a tapered shape in which the cross-sectional area becomes smaller as it approaches the opening on the ink ejection side.

[0058] The relationship between the mesh diameters of the in-filter F1 and out-filter F2 and the nozzle diameter of the nozzle N is preferably such that the nozzle diameter of the nozzle N≧the mesh diameter of the out-filter F2≧the mesh diameter of the in-filter F1.

[0059] This is because the mesh diameter of the in-filter F1 must be sufficiently smaller than the nozzle diameter of the nozzle N to prevent the nozzle N from being clogged with foreign matter such as particles. In addition, since the mesh diameter of the outfilter F2 is sufficient if it is capable of preventing foreign matter from entering from the outside, it is preferable to make the diameter as large as possible within the range equal to or less than the nozzle diameter of the nozzle N, in order to reduce the pressure loss when the liquid passes through.

[0060] The nozzle diameter of the nozzle N can be specifically set to 18 μm to 40 μm. For example, if the nozzle diameter of the nozzle N is set to 20 μm, the mesh diameter of the in-filter F1 can be set to 10 μm, and the mesh diameter of the out-filter F2 can be set to 20 μm.

[0061] [Effects of the invention] As described above, the droplet ejection head 30 according to this embodiment includes an out-filter chamber 422 in which an out-filter F2 for capturing foreign matter contained in the liquid is provided in the discharge flow path 42 through which the liquid discharged from the head unit 50 passes. The out-filter chamber 422 includes a liquid inlet 4221 through which the liquid discharged from the head unit 50 flows in, and a liquid outlet 4222 through which the liquid in the out-filter chamber 422 flows out. The out-filter F2 is provided in contact with the inner wall portion of the upper wall and the inner wall portion of the lower wall of the out-filter chamber 422 so as to divide the out-filter chamber 422 into a front chamber 422A including the liquid inlet 4221 and a rear chamber 422B including the liquid outlet 4222. The front chamber 422A has a cross-sectional area H on a horizontal plane at the upper end greater than the area of ​​the opening of the liquid inlet 4221.

[0062] According to this configuration, the liquid discharged from the head portion 50 flows into the front chamber 422A with its flow rate increased by the relatively narrow liquid inlet 4221. Since the cross-sectional area H of the horizontal plane at the upper end of the front chamber 422A is relatively larger than the liquid inlet 4221, the flow resistance of the front chamber 422A and the amount of decrease in the flow rate of the liquid are reduced, making it easier for the liquid to flow to the back side (+Z direction side) of the front chamber 422A. As a result, the difference in the liquid flow rate between the upper and lower parts of the out-filter F2 is less likely to occur, and the pressure loss when the liquid passes through the out-filter F2 is small. Therefore, it is possible to prevent the pressure difference between the supply flow path 41 side and the discharge flow path 42 side from decreasing, thereby preventing a decrease in the discharge performance of the nozzle N.

[0063] As shown in FIG. 4, the out-filter F2 is provided extending in the vertical direction (Z direction) so as to contact the upper and lower ends of the inner wall of the out-filter chamber 422. With this configuration, even if the area of ​​the out-filter F2 is increased to further reduce the pressure loss when the liquid passes through the out-filter F2, the inkjet head 30 is unlikely to become large in the horizontal direction (direction parallel to the XY plane). Therefore, when multiple inkjet heads 30 are arranged side by side, problems such as difficulty in connecting the joints or an increase in the size of the inkjet head 30 carriage are unlikely to occur.

[0064] [Modifications of the opposing surface or out-filter] 4 is merely one example of a case in which the out-filter chamber 422 is provided so that the cross-sectional area H of the horizontal plane at the upper end of the front chamber 422A is larger than the area of ​​the opening of the liquid inlet 4221. Therefore, in addition to the structure shown in FIG. 4, the following structure may also be used.

[0065] Here, the surface of the front chamber 422A facing the out-filter F2 is referred to as a facing surface 4223. For example, examples of modified opposing surface 4223 in which the distance from the out-filter F2 increases from the lower end to the upper end include a stepped opposing surface 4223 as shown in FIG. 5A, a curved opposing surface 4223 as shown in FIG. 5B, or an opposing surface 4223 having both a portion that is approximately perpendicular to the nozzle surface 5221 and a portion that is not perpendicular to the nozzle surface 5221 as shown in FIG. 5C.

[0066] In addition, the opposing surface 4223 may be arranged approximately perpendicular to the nozzle surface 5221, and the out-filter F2 may be arranged at a predetermined angle so as to increase the distance between the opposing surface 4223 and the out-filter F2, thereby making the cross-sectional area H in the horizontal plane at the upper end of the front chamber 422A larger than the area of ​​the opening of the liquid inlet 4221. Modified examples of such an out-filter F2 include a linear out-filter F2 as shown in FIG. 6A, and a curved out-filter F2 as shown in FIG. 6B.

[0067] In addition, in the above, only the case where at least one of the opposing surface 4223 and the out-filter F2 is provided substantially perpendicular to the nozzle surface 5221 has been illustrated, but this is not limited to the case. For example, as shown in Fig. 7, both the out-filter F2 and the opposing surface 4223 may be provided at an angle so that the distance between them is increased.

[0068] Furthermore, the configuration is not limited to one in which the distance between the opposing surface 4223 and the out-filter F2 gradually increases toward the top, and as long as the cross-sectional area H of the horizontal plane at the upper end of the anterior chamber 422A is at least larger than the area of ​​the opening of the liquid inlet 4221, the flow resistance of the anterior chamber 422A will be small. Therefore, for example, the opposing surface 4223 or the out-filter F2 may have a shape having a constriction, and the horizontal cross-sectional area of ​​a part of the front chamber 422A excluding the upper end portion may be smaller than the area of ​​the opening of the liquid inlet 4221.

[0069] Of course, other specific details of the structure can be modified as appropriate. [Explanation of symbols]

[0070] 1 Inkjet recording device (droplet ejection device) 30 Inkjet head (droplet ejection head) 41 Supply Channel 42 Exhaust flow path 422 Out Filter Room 422A Anteroom 422B rear chamber 4221 Liquid inlet 4222 Liquid outlet 4223 Opposite surface 50 Head 5221 Nozzle surface F1 Infilter F2 Out Filter N Nozzle H cross-sectional area

Claims

1. A head portion provided with a nozzle for ejecting droplets; A supply flow path that supplies liquid to the head portion; a discharge flow path through which liquid discharged from the head portion passes, the discharge flow path includes an out-filter chamber provided with an out-filter that captures foreign matter contained in the liquid discharged from the head portion, the out-filter chamber includes a liquid inlet through which liquid discharged from the head portion flows in, and a liquid outlet through which liquid in the out-filter chamber flows out, the out-filter is provided in contact with an upper inner wall portion and a lower inner wall portion of the out-filter chamber so as to divide the out-filter chamber into two chambers, a front chamber including the liquid inlet and a rear chamber including the liquid outlet, The liquid droplet ejection head is characterized in that the cross-sectional area of ​​the front chamber in a horizontal plane at an upper end portion is larger than the area of ​​an opening of the liquid inlet.

2. The droplet ejection head according to claim 1 , further comprising a circulation flow path that circulates the liquid passing through the discharge flow path to the supply flow path.

3. 3. The droplet ejection head according to claim 1, wherein the supply flow path includes an in-filter that captures foreign matter contained in the liquid supplied to the head portion.

4. The diameter of the nozzle is equal to or larger than the diameter of the mesh of the outfilter, 4. The droplet ejection head according to claim 3, wherein a mesh diameter of the out-filter is equal to or larger than a mesh diameter of the in-filter.

5. 5. The droplet ejection head according to claim 3, wherein an area of ​​the in-filter is larger than an area of ​​the out-filter.

6. the out-filter is provided substantially perpendicular to the nozzle surface, The droplet ejection head according to claim 1 , wherein the front chamber has an opposing surface facing the out-filter, the opposing surface being shaped such that the distance between the front chamber and the out-filter increases from the lower end to the upper end.

7. the front chamber has a surface facing the out-filter that is substantially perpendicular to the nozzle surface, 6. The droplet ejection head according to claim 1, wherein the out-filter is inclined at a predetermined angle with respect to the nozzle surface in a direction away from the opposing surface.

8. 8. The droplet ejection head according to claim 1, wherein a flow rate of the liquid passing through the out-filter is 50 ml / min or more and 160 ml / min or less.

9. 9. The droplet ejection head according to claim 1, wherein the viscosity of the droplets ejected from the nozzle is 5 cp or more and 15 cp or less.

10. A droplet ejection device comprising the droplet ejection head according to claim 1 .

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