JP2019217677A - Ink jet head and ink jet recording device - Google Patents

Abstract

To provide an ink jet head and an ink jet recording device that enable improved uniformity and stability in ejection of ink from a large number of nozzles.SOLUTION: An ink jet head 1 comprises: discrete flow paths 111 each of which supplies ink to corresponding one of multiple nozzles; and a common flow path 124 in communication with the discrete flow paths. The common flow path includes: a supplying ink flow path 124a; a discharging ink flow path 124b; and a gap 128 including discrete supply ports 127. The gap has a damping portion 126 spreading over a disposition area 1270 in which the discrete supply ports are disposed. At least in the disposition area with respect to an X direction in a longitudinal direction of the disposition area, the supplying ink flow path and the discharging ink flow path are connected to different sides in a Y direction relative to the gap. At least in an area including the disposition area with respect to the X direction, the supplying ink flow path and the discharging ink flow path each have a representative length, which is related to flow path resistance, in a section perpendicular to the X direction, greater than the gap in a surface perpendicular to the Y direction.SELECTED DRAWING: Figure 5

Description

  The present invention relates to an inkjet head and an inkjet recording device.

  2. Description of the Related Art There is an ink jet recording apparatus that discharges ink from a nozzle and lands on a medium to form an image, a film, a structure, and the like. In an ink jet recording apparatus, a large number of nozzles are arranged at narrow intervals in response to a demand for higher precision of an image, and ink is supplied to these nozzles from a common ink flow path through individual flow paths to the respective nozzles. Supplied.

  Each individual flow path is provided with a pressure chamber for applying a pressure fluctuation to the ink. The pressure fluctuation applied to the ink in the pressure chamber is transmitted not only in the nozzle direction but also in the direction of the common ink flow path in the ink, and further transmitted to other individual flow paths, thereby adversely affecting ink ejection. May be given. On the other hand, conventionally, there is a technique in which a damping portion (damper) is provided in a common ink flow path to attenuate the transmitted pressure fluctuation, thereby suppressing an adverse effect on ink ejection from other nozzles (Patent Literature) 1).

  On the other hand, bubbles or foreign matter may be mixed into the ink supplied to the nozzle, or a specific component may be separated from the ink that is not ejected from the nozzle for a long time. When the air bubbles or the like stay in the individual flow channel or near the individual flow channel, the ink is not supplied to the nozzles properly, and the ink is not properly discharged from the nozzles, leading to a problem of deterioration in image quality. On the other hand, there is a technique in which a flow path for discharging ink is provided separately from the nozzle, and bubbles and foreign substances are discharged from the flow path together with the ink, and the ink is collected.

JP 2015-44324 A

  However, conventionally, when an ink flow for discharging ink including bubbles and the like is generated in the ink storage section, a pressure difference is generated due to a pressure loss generated between the upstream side and the downstream side of the flow among a large number of nozzles. As a result, there is a problem that a difference is caused in the ink ejection characteristics from the nozzles and the image quality is adversely affected.

  An object of the present invention is to provide an ink jet head and an ink jet recording apparatus capable of discharging ink more uniformly and stably from a large number of nozzles.

In order to achieve the above object, the invention according to claim 1 is:
A plurality of individual flow paths for supplying ink to a plurality of nozzles for discharging ink,
A common channel communicating with the plurality of individual channels,
With
The common channel is provided with an inflow portion into which ink flows in from the outside, an outflow portion into which ink flows out, and a plurality of supply ports connected to each of the individual flow channels between the inflow portion and the outflow portion. Including a connection portion,
The connection unit has a vibration damping unit that is provided on a surface opposite to the opening surface provided with the plurality of supply ports and covers an arrangement range of the plurality of supply ports, and suppresses a pressure variation in ink.
The inflow portion and the outflow portion are connected to each other in a second direction perpendicular to the first direction within the opening plane at least in the arrangement range in a first direction along a longitudinal direction of the arrangement range. Connected to different sides of the
In a range including at least the arrangement range in the first direction, the representative length of the inflow portion and the outflow portion related to the flow path resistance in a cross section perpendicular to the first direction is the second length of the connection portion. An ink jet head having a length greater than the representative length related to the flow path resistance in a plane perpendicular to the direction.

According to a second aspect of the present invention, in the inkjet head according to the first aspect,
The representative length of the inflow portion and the outflow portion is a smaller value of a height in a third direction perpendicular to the opening surface of the inflow portion and the outflow portion and a width in the second direction. And
The representative length of the connection part is a height of the connection part in the third direction.

According to a third aspect of the present invention, in the inkjet head according to the first or second aspect,
Each of the inflow section and the outflow section has a cross-sectional area perpendicular to the first direction larger than a cross-sectional area of the connection section perpendicular to the second direction.

According to a fourth aspect of the present invention, in the inkjet head according to any one of the first to third aspects,
An ink inflow port to the inflow section and an ink outflow port from the outflow section are provided on different outsides of the arrangement range in the first direction.

According to a fifth aspect of the present invention, in the inkjet head according to any one of the first to fourth aspects,
The inflow section, the connection section, and the outflow section each extend parallel to the first direction.

According to a sixth aspect of the present invention, in the inkjet head according to any one of the first to fifth aspects,
The lengths of the inflow portion, the connection portion, and the outflow portion in the first direction are the same.

According to a seventh aspect of the present invention, in the inkjet head according to any one of the first to sixth aspects,
The plurality of supply ports are provided on a plurality of arrays extending in the first direction at positions different from each other in the second direction of the opening surface,
The shape of the outflow portion is determined according to the arrangement range of the arrangement closest to the outflow portion in the array.

The invention according to claim 8 is the ink jet head according to claim 7, wherein
The shape of the inflow portion is determined in accordance with the arrangement range of the arrangement closest to the inflow portion in the array.

According to a ninth aspect of the present invention, in the inkjet head according to any one of the first to eighth aspects,
The vibration damping portion is provided to extend in a direction of the opening surface from a surface opposite to the opening surface in a third direction perpendicular to the opening surface in the common flow channel, and is provided with the inflow portion and the inflow portion. The partition is provided at an end of the partition wall that separates the outflow portion in the second direction on the opening surface side.

According to a tenth aspect of the present invention, in the inkjet head according to the ninth aspect,
The inside of each of the connecting portion and the inflow portion is hollow at least on the opening surface side of the vibration damping portion in the third direction.

According to an eleventh aspect of the present invention, in the inkjet head according to any one of the first to tenth aspects,
The vibration damping portion is integrally fixed to a surface of the common flow channel facing the opening surface.

According to a twelfth aspect of the present invention, in the inkjet head according to any one of the first to eleventh aspects,
The surface of the vibration suppression unit on the side facing the opening surface has a convex shape in a normal state in which the common flow path is filled with ink.

According to a thirteenth aspect of the present invention, in the inkjet head according to any one of the first to twelfth aspects,
The inflow portion is provided with a deaeration port capable of discharging bubbles.

According to a fourteenth aspect of the present invention, in the inkjet head according to the thirteenth aspect,
The outlet for the ink from the deaeration port and the outlet for the ink from the outlet are each open upward in the direction of gravity.

The invention according to claim 15 is
An inkjet recording apparatus comprising the inkjet head according to any one of claims 1 to 14.

The invention according to claim 16 is the ink jet recording apparatus according to claim 15,
The ink jet printer according to the present invention is characterized in that the ink jet printer further includes a circulation flow path that allows the ink flowing out of the outlet to flow into the inlet again.

  ADVANTAGE OF THE INVENTION According to this invention, there exists an effect that ink can be more uniformly and stably discharged from many nozzles.

1 is an overall schematic view of an inkjet recording apparatus according to an embodiment. FIG. 3 is a bottom view of the head unit as viewed from an ink ejection surface side. FIG. 2 is a schematic view of the appearance of an inkjet head. FIG. 3 is a diagram illustrating an ink flow path to an inkjet head. FIG. 3 is a diagram illustrating an internal structure of an ink supply unit. FIG. 9 is a diagram illustrating a first modification of the internal structure of the ink supply unit. FIG. 13 is a diagram illustrating a second modification of the internal structure of the ink supply unit. FIG. 13 is a diagram illustrating a third modification of the internal structure of the ink supply unit.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is an overall schematic diagram of an inkjet recording apparatus 100 according to the present embodiment. The inkjet recording apparatus 100 includes a head unit 10, a transport unit 20, and the like.

  The transport unit 20 includes, but is not limited to, two transport rollers 20a and 20b, an annular transport belt 20c, and the like. The transport rollers 20a and 20b are arranged in parallel with the direction in which the rotation axis extends in the X direction. The transport belt 20c is stretched between the transport rollers 20a and 20b, and moves around when the transport roller 20a rotates according to the operation of a transport motor (not shown). The transport roller 20b rotates according to the orbital movement of the transport belt 20c. In a section in which the outer peripheral surface (transport surface) of the transport belt 20c is oriented in the Z direction (upward), the recording medium M placed on the outer peripheral surface is transported in the Y direction according to the orbital movement of the transport belt 20c. .

  The head unit 10 records an image on the recording medium M transported by the transport unit 20 by discharging ink at an appropriate timing based on the image data. The head unit 10 is arranged such that the ink can be ejected in the direction of the transport surface within a range where the recording medium M is placed on the transport surface, and here, the transport surface and the ink ejection surface are opposed to each other. . In the ink jet recording apparatus 100, for example, four head units 10 that respectively eject four color inks of yellow (Y), magenta (M), cyan (C), and black (K) include, for example, a recording medium. The colors are arranged at predetermined intervals in the order of Y, M, C, and K from the upstream side in the transport direction of M. The number of head units 10 need not be four, and ink of the number of colors corresponding to the number of head units 10 can be ejected. Further, in addition to the colored ink, a transparent ink for forming a film or the like may be included.

  FIG. 2 is a bottom view of the head unit 10 as viewed from the ink ejection surface side. The head unit 10 has a plurality of, here eight, ink jet heads 1 each, and these ink jet heads 1 are fixedly held on a support member. In each of the inkjet heads 1, openings N of a plurality of nozzles are arranged on the ink ejection surface (nozzle surface) of the head chip 11. Here, the openings N are provided on nozzle rows extending in the X direction (direction perpendicular to the transport direction) at three positions in the Y direction (transport direction). The openings N are arranged at predetermined intervals (nozzle intervals) continuously over the width in which images can be recorded on the recording medium M in the X direction as a whole.

  The recording medium M is not particularly limited, but may be a sheet cut to a certain size. The recording medium M is supplied onto a conveyance belt 20c from a medium supply unit (not shown), and ink ejected from the head unit 10 lands to record an image (may include drying and fixing operations as necessary). After that, the sheet is sent from the transport section 20 to the medium discharge section. Alternatively, roll paper may be used as the recording medium M. Further, as the recording medium M, in addition to paper such as plain paper or coated paper, various media such as cloth or sheet-like resin that can fix ink that has landed on the surface may be used.

FIG. 3 is a schematic external view of the inkjet head 1.
The inkjet head 1 includes a head chip 11, an ink supply unit 12, a drive control unit 13, and the like.

  The head chip 11 has a plurality of nozzles (openings N) for discharging ink, individual flow paths 111 (see FIG. 5) for supplying ink from the ink supply unit 12 to each nozzle, and a plurality of nozzles for discharging ink from the nozzles. A pressure operation unit (not shown) for applying pressure fluctuation is provided. The drive control unit 13 is provided with a circuit board and a drive chip (such as an IC) for outputting a drive signal to the pressurizing operation unit.

  The ink supply unit 12 communicates with each individual flow path (that is, each nozzle) of the head chip 11 and stores ink to be supplied to the individual flow path. On the upper side (+ Z side) of the ink supply unit 12, an inlet 121 (inlet), an outlet 122 (outlet), an air outlet 123, and the like are provided. The ink supply unit 12 is formed using, for example, SUS.

  The inflow port 121 allows ink supplied from an external ink tank to flow. The outlet 122 allows the ink to flow out to an external ink tank. The deaeration port 123 is an opening for discharging a part of the air mixed into the ink supply unit 12. The deaeration port 123 is normally sealed with a lid member or the like, and may be opened only when necessary to discharge air bubbles.

FIG. 4 is a diagram illustrating an ink flow path to the inkjet head 1.
The ink jet recording apparatus 100 includes a main tank 91, a supply sub-tank 92, a reflux sub-tank 93, and the like.

  The main tank 91 stores the ink supplied to the supply sub-tank 92. The main tank 91 is connected to a supply sub-tank 92 by an ink flow path 71 via a liquid feed pump 81. By the operation of the liquid sending pump 81, the ink is sent from the main tank 91 to the supply sub-tank 92.

  The supply sub-tank 92 stores ink supplied to the ink supply unit 12 of the inkjet head 1. The supply sub-tank 92 is connected to the inflow port 121 by the ink flow path 72.

  The reflux sub-tank 93 stores the ink discharged from the ink supply unit 12. The reflux sub-tank 93 is connected to the outlet 122 by the ink flow path 73.

The supply sub-tank 92 and the reflux sub-tank 93 are connected by an ink flow path 74 via a liquid feed pump 82. By the operation of the liquid supply pump 82, the ink in the reflux sub-tank 93 is returned to the supply sub-tank 92.
The ink flow paths 73 and 74, the reflux sub-tank 93, and the liquid feed pump 82 constitute a circulation flow path in the inkjet recording apparatus 100 of the present embodiment.

  The supply sub-tank 92 is provided at a position higher in the vertical direction than the ink discharge surface of the head chip 11, and the reflux sub-tank 93 is provided at a position lower in the vertical direction than the ink discharge surface. Therefore, the ink at the inlet 121 depends on the pressure P1 due to the head difference between the liquid surface of the supply sub-tank 92 and the ink discharge surface and the pressure P2 due to the head difference between the ink discharge surface and the reflux sub-tank 93. Is higher than the pressure of the ink at the outlet 122. The height (that is, the pressure P2) of the supply sub-tank 92 and the reflux sub-tank 93 in the vertical direction may be changeable.

  FIG. 5 is a diagram illustrating the internal structure of the ink supply unit 12. FIG. 5A is a sectional view taken along a sectional line AA in FIG. Here, in order to show the positional relationship, the individual flow path 111 and the individual supply port 127 which are not on the sectional line AA are shown in a see-through manner. FIG. 5B is a perspective view of the inside of the ink supply unit 12 from above (on the side of the drive control unit 13).

  A space that extends in the X direction (first direction) and forms a common flow path 124 is provided inside the ink supply unit 12. The common channel 124 has two areas in the Y direction (second direction) and a connection region (connection portion) thereof. Of the two areas, the side provided with the inlet 121 (here, the + Y side) is the supply ink flow path 124a (inflow portion), and the side provided with the outlet 122 (here, the -Y side). Are discharge ink flow paths 124b (outflow portions), and the direction along the X direction is the longitudinal direction. The deaeration port 123 is provided in the supply ink channel 124a.

  Between the supply ink flow path 124a and the discharge ink flow path 124b, a partition wall 125 extends downward (-Z direction) from the inner wall surface on the upper side (+ Z side), and is separated from the lower inner wall surface (bottom surface, opening surface). A gap 128 (connection portion) through which ink passes between the supply ink flow path 124a and the discharge ink flow path 124b is provided therebetween. The wall surface (the surface facing the opening surface) that forms the upper surface of the gap 128 is a vibration damper 126 (damper), and extends in the Y direction. That is, the vibration damper 126 is fixedly formed integrally with the wall surface of the common flow channel 124 via the partition 125. Specifically, the wall surface of the common flow channel 124 and the partition 125 are continuously formed of, for example, a liquid crystal polymer, and a thin film is applied to a lower end (damper frame) of the partition 125. With such a structure, the supply ink flow path 124a and the discharge ink flow path 124b are connected to different sides of the gap 128 in the Y direction.

  Here, the damping unit 126 is fixed to the common flow channel 124 only by the partition wall 125, and is −Z higher than the other surface including the lower inner wall, in particular, the surface facing the opening surface of the damping unit 126. No support member or the like is provided on the direction side. Similarly, the inner wall of the common flow channel 124 does not have a protruding member other than the partition 125. Due to the hollow common flow path 124 having no support member or protrusion member, bubbles or foreign matters are caught on the support member or protrusion member in accordance with the flow of ink passing through the gap 128, and near the individual supply port 127. It prevents the occurrence of persistent situations.

  The damping section 126 faces the individual supply ports 127 (plural supply ports) for the individual flow paths 111 of the head chip 11 provided on the bottom surface of the common flow path 124. When the pressure fluctuation is applied to the ink in the individual flow channel 111, the pressure wave flows backward through the individual flow channel and is transmitted to the common flow channel 124. The vibration suppression unit 126 attenuates this pressure wave (suppresses pressure fluctuations in the ink). In addition, the vibration suppression unit 126 suppresses not only such a pressure wave but also a pressure fluctuation related to a temporary fluctuation of the ink amount in the individual flow path 111 in accordance with the ink ejection from the nozzle. For this reason, the vibration control unit 126 determines that the end position of the individual supply port 127 in the arrangement range 1270 (the ± X direction of the arrangement range 1270 (the longitudinal direction of the arrangement range 1270)) of all the individual supply ports 127 in plan view. (Equal to the outer edge positions of the individual supply ports 127 at both ends in the X direction). The vibration suppression unit 126 does not need to be provided in the Y direction with a width larger than the width in the Y direction of the arrangement range 1270 of the individual supply ports 127, and has a length having a certain margin according to the width. May be. On the other hand, here, the damping unit 126 is provided in the X direction in parallel with the same length (range) as the supply ink flow path 124a and the discharge ink flow path 124b. Further, the height of the gap 128 in the Z direction (third direction) is so wide that the vibration of the damping section 126 is not hindered, the ink flow is not extremely disturbed by the vibration, and the pressure wave is individually supplied. It is narrow enough to be effectively attenuated before widespread from the mouth 127. The height in the Z direction and the width in the Y direction of the supply ink flow path 124a and the discharge ink flow path 124b are sufficiently (at least three times or more) larger than the height of the gap 128 in the Z direction.

  Examples of the vibration damping unit 126 include a configuration that deforms so as to attenuate pressure fluctuations caused by pressure waves reaching the surface, for example, an elastic plate or an elastic member via an air layer. As the elastic plate or the elastic member (such as a thin film), a well-known member which does not deteriorate due to ink, for example, a polyimide or a liquid crystal polymer may be used. The opening surface side (−Z side) of the vibration damping section 126 has a downward convex shape (convex shape) in a normal state, that is, in an equilibrium state where the ink is filled in the ink supply section 12. As a result, the air bubbles that have entered between the damping unit 126 and the individual supply ports 127 easily flow out to the supply ink flow path 124a or the discharge ink flow path 124b according to the buoyancy.

  The ink supplied from the inflow port 121 flows into the gap 128 from the supply ink flow path 124a, and a part of the ink is supplied from the individual supply port 127 to each nozzle. The remaining ink flows into the discharge ink flow path 124 b through the gap 128 and is discharged from the outlet 122. Although not particularly limited, here, the inflow port 121 is provided outside the arrangement range 1270 of the individual supply port 127 in the −X direction. Further, the outlet 122 is provided outside the arrangement range 1270 in the + X direction (that is, on the side different from the inlet 121).

  As described above, the ink that is not supplied to the individual flow channel 111 is discharged from the outlet 122 one by one without successively staying in the common flow channel 124 for a long time, then returns to the supply sub-tank 92, and flows again from the inlet 121. Is possible. As a result, bubbles and foreign substances in the ink are discharged without wasting the ink, and the ink is prevented from stagnating inside the common flow path 124 to separate components.

  The individual flow channel 111 does not need to penetrate the head chip 11 vertically in a straight line, and may be bent in accordance with the arrangement of the above-described pressurizing operation unit.

  A pressure loss corresponding to the distance of the gap 128 (the distance of the ink flow in the XY plane) occurs in the ink flowing through the gap 128. The flow path resistance of the ink flow path that causes pressure loss for a predetermined ink is determined by the flow path cross-sectional area and the circumference of the flow path cross section (collectively, equivalent diameter = 4 × flow path cross-sectional area / perimeter; flow path resistance) Or the length of the short axis or the length of the short side (the smaller of the vertical and horizontal widths in the YZ plane may be the representative length), the flow path length, and the flow velocity. . As described above, the height (length of the short side) of the gap 128 is sufficient compared to the length (width) in the Y direction and the length (height) in the Z direction of the supply ink flow path 124a. Accordingly, the equivalent diameter in both the YZ plane (the plane perpendicular to the longitudinal direction) and the XZ plane of the supply ink flow path 124a is within the XZ plane (the plane perpendicular to the first direction). Is sufficiently larger than the equivalent diameter of the gap 128. Since the flow path resistance increases in accordance with the reciprocal of the equivalent diameter, the pressure loss in the supply ink flow path 124a for the ink is sufficiently small as compared with the pressure loss generated in the gap 128. In addition, since the cross-sectional area of the supply ink flow path 124 a in the YZ plane is increased, the ink flow velocity is sufficiently smaller than the ink flow velocity in the gap 128. Since the pressure loss is proportional to the ink flow velocity, the pressure loss related to the flow of ink in the X direction in the supply ink flow path 124a is sufficiently reduced. That is, the ink that has flowed in from the inflow port 121 spreads in the supply ink flow path 124a without substantially causing a pressure difference in the X direction.

  Similarly, the discharge ink flow path 124b has a short side length, an equivalent diameter, and a cross-sectional area at each cross section that are sufficiently larger than the height, the equivalent diameter, and the opening area (cross-sectional area) of the gap 128 in the XZ plane. The pressure loss in the discharged ink flow path 124b of the ink is sufficiently smaller than the pressure loss generated in the ink when passing through the gap 128. In addition, since the cross-sectional area of the discharge ink flow channel 124b in the YZ plane is increased, the ink flow speed is sufficiently smaller than the ink flow speed in the gap 128. That is, the ink flowing out of the gap 128 flows out of the outlet 122 without substantially causing a difference in pressure loss in the X direction in the discharge ink flow path 124b. Thus, the ink flowing through the gap 128 has a substantially uniform pressure distribution in the X direction.

  The supply ink flow path 124a has a larger cross-sectional area in the YZ plane than in the + Z direction, here, the upper side in the vertical direction and the lower side. As a result, the bubbles in the supply ink flow path 124a are deflected upward due to buoyancy, and are less likely to be drawn into the gap 128 due to the low flow velocity, so that the individual flow paths 111 and the like are less likely to be adversely affected. Bubbles remaining above the supply ink flow path 124a can be easily discharged from the deaeration port 123. If the upward direction of gravity in mounting the inkjet head 1 to the inkjet recording apparatus 100 is different from the + Z direction, the deaeration port 123 is provided at a position near the upper end in the direction of gravity of the supply ink flow path 124a and / or the discharge ink flow path 124b. The outlet 122 may be provided, and the supply ink flow path 124a and / or the discharge ink flow path 124b may be provided in such a shape that the cross-sectional area increases as the horizontal surface on the upper side in the direction of gravity. That is, even when the ink ejection surface (the normal direction to the outward direction; equal to the ink ejection direction) is not downward in the direction of gravity, at least one of the deaeration port 123 and the outlet 122 is directed upward in the direction of gravity in the inkjet head 1. The common flow path 124 and the gap 128 may be arranged so as to open (that is, the deaeration port 123 and the outflow port 122 may be inclined with respect to the ink ejection surface).

  In the inkjet head 1 of the present embodiment, the width of the supply ink flow path 124a in the X direction includes the arrangement range 1270 where the individual supply ports 127 are provided. Therefore, the ink causing almost no pressure loss at each position in the X direction flows into the gap 128 almost uniformly (at substantially constant speed) in the Y direction, and further flows into the individual supply ports 127 respectively. Thus, the magnitude of the pressure loss of the ink up to the nozzles arranged in the X direction becomes substantially uniform among the nozzles. Further, here, the individual supply ports 127 are provided at three different positions (three rows) in the Y direction, but the three rows have sufficiently small intervals in the Y direction. Therefore, even when the ink flows at a flow rate necessary for discharging bubbles, foreign matter, and the like, since the ink flow is substantially directed in the Y direction, the ink flow from the supply ink flow path 124a to each individual supply port 127 is possible. The difference in the pressure of the ink due to the difference in the distance is sufficiently small.

FIG. 6 is a diagram illustrating a first modification of the internal structure of the ink supply unit 12.
As in the above embodiment, even if there are three individual supply ports 127 in the Y direction, there is a slight difference in the range of the openings in the X direction in each row. As a result, the difference between the columns at both ends may be slightly large. Here, arrangement range 1270 is shown as a parallelogram.

  In such a case, the supply ink flow path 124a is formed on the XZ plane according to the arrangement range in the X direction of the individual supply ports 127 in the row closest to the supply ink flow path 124a among the plurality of rows. A range in which the equivalent diameter in the inside and in the YZ plane is larger than the equivalent diameter of the gap 128 in the XZ plane may be determined. Similarly, the discharge ink flow path 124b is arranged in the XZ plane and in the YZ plane in accordance with the arrangement range in the X direction of the individual supply ports 127 in the row closest to the discharge ink flow path 124b among the plurality of rows. Each equivalent diameter in the plane can be set larger than the equivalent diameter of the gap 128 in the XZ plane.

  Outside these ranges, the supply ink flow path 124a and the discharge ink flow path 124b may not be formed or provided to be narrower, respectively. Here, the boundary where the shape changes in the YZ plane is set to be inclined according to the inclination of the arrangement range 1270 with respect to the Y direction. The flow of the ink in the gap 128 may be entirely inclined in the Y direction between the supply ink flow path 124a and the discharge ink flow path 124b by this inclination angle according to the nozzle arrangement. The magnitude of the increase in pressure loss due to this inclination is very small. In addition, at least above the individual supply port 127, bubbles and foreign matter do not stay due to the stable ink flow, which has an adverse effect on ink supply to the individual supply port 127 and pressurization of ink in the individual flow path 111. Is not affected.

FIG. 7 is a diagram illustrating a second modification of the internal structure of the ink supply unit 12.
In the ink supply unit 12 according to the second modification, similarly to the first modification, the arrangement range 1270 of the individual supply port 127 is a parallelogram.

  As shown in FIG. 7A, the supply ink flow path 124a is narrower outside the arrangement range 1270 in the + X direction. Further, the discharge ink flow path 124b is narrower outside in the -X direction than the arrangement range of the row of the individual supply ports 127 closest to the discharge ink flow path 124b.

  As shown in FIG. 7B, in the cross section taken along the cross section line BB, the supply ink flow path 124a has an upper inner wall surface (the surface on the + Z side, the upper surface) lower than the upper inner wall surface of the discharge ink flow path 124b. I have. As shown in FIG. 7C, in the cross section along the cross section line CC, the discharge ink flow path 124b has a lower inner wall surface (the surface on the -Z side, the bottom surface) than the lower inner wall surface of the supply ink flow path 124a. Is getting higher.

  As described above, by lowering the position of the upper inner wall surface of the discharge ink flow path 124b, the amount of ink flowing to the discharge ink flow path 124b without passing above the individual supply port 127 is reduced, and the position above the arrangement range 1270 is reduced. The flow itself can be made less likely to stagnate. The portion where the position of the lower inner wall surface of the supply ink flow path 124 a is raised corresponds to the position of the deaeration port 123. That is, while reducing the inflow of ink into this portion, the mixed air bubbles float in the ink and are easily guided to the deaeration port 123.

  In this case, the direction of the ink flow as a whole in the gap 128 is more maintained in the −Y direction than in the case of the first modification. That is, the distance in which the ink flows through the section where a large pressure loss occurs is kept almost the shortest.

  Note that the position of the upper inner wall surface of the discharge ink flow path 124b is equal to the position of the lower inner wall surface in the above range, that is, the discharge ink flow path 124b may not have the discharge ink flow path 124b. In addition, the position of the lower inner wall surface of the supply ink flow path 124a is equal to the position of the upper inner wall surface unless the deaeration port 123 is provided, that is, the supply ink flow path 124a is provided in that portion. There may be no shape.

FIG. 8 is a diagram illustrating a third modification of the internal structure of the ink supply unit 12.
In the ink supply unit 12 of the third modification, the lower inner wall surfaces of the supply ink flow path 124a and the discharge ink flow path 124b are formed at both ends in the X direction to be higher. Further, as shown in the cross-sectional view along the cross-sectional line AA (FIG. 8B), the discharge ink flow path 124b does not extend at the end in the −X direction side. These correspond to portions where the inflow port 121, the outflow port 122, and the deaeration port 123 are provided, respectively. That is, the flow path becomes narrow immediately after the ink flows in from the inflow port 121 and immediately before the ink supplied to the nozzle flows into each of the individual supply ports 127 and is supplied to the outflow port 122. It does not work to make the pressure loss different for each flow path passing through.

  In addition, in the above-mentioned modified examples 1 to 3, since the ink can stay in the portion corresponding to the deaeration port 123, there may be a flow path connecting these. The equivalent diameter of this flow path is sufficiently smaller than the equivalent diameter of the gap 128 in the direction of ink flow (here, the Y direction).

As described above, the inkjet head 1 of the present embodiment includes a plurality of individual channels 111 that supply ink to a plurality of nozzles that eject ink, a common channel 124 that communicates with the plurality of individual channels 111, Is provided. The common flow path 124 includes a supply ink flow path 124a into which ink flows from the outside, a discharge ink flow path 124b from which ink flows out, and an individual flow path 111 between the supply ink flow path 124a and the discharge ink flow path 124b. And a gap 128 provided with a plurality of individual supply ports 127 connected to each of them. One end surface of the gap 128 is provided on a surface opposite to the opening surface in which the plurality of individual supply ports 127 are provided, and covers the arrangement range 1270 of the plurality of individual supply ports 127 to suppress pressure fluctuation in ink. Part 126. The supply ink flow path 124a and the discharge ink flow path 124b are arranged at least in the arrangement range 1270 in the X direction (first direction) along the longitudinal direction of the arrangement range 1270, and in the Y direction (vertical to the X direction in the opening plane). (Second direction), they are connected to different sides of the gap 128. In a range including at least the arrangement range 1270 in the X direction, the representative length (for example, equivalent diameter) related to the flow path resistance in a cross section perpendicular to the X direction of the supply ink flow path 124a and the discharge ink flow path 124b is Y of the gap 128. It is larger than the representative length related to the flow path resistance in a plane perpendicular to the direction.
Accordingly, the pressure loss in the supply ink flow path 124a and the discharge ink flow path 124b is sufficiently reduced as compared with the pressure loss in the gap 128, and thus a pressure gradient is generated particularly in the longitudinal direction of the arrangement range 1270. Do not let. Further, since the ink flows in the gap 128 substantially perpendicularly to the longitudinal direction of the arrangement range 1270, the difference in pressure loss in the gap 128 with respect to each individual flow path 111 is sufficiently suppressed. In addition, since the ink flow can be appropriately generated in the gap 128, it is possible to appropriately discharge air bubbles, foreign matter, and separated ink from the ink. As a result, in the inkjet head 1, the ink can be ejected from each nozzle stably and evenly.

  The representative lengths of the supply ink flow path 124a and the discharge ink flow path 124b are the height and Y in the Z direction (third direction) perpendicular to the opening surfaces of the supply ink flow path 124a and the discharge ink flow path 124b. It is the smaller value of the widths in the direction, and the representative length of the gap 128 is the height of the gap 128 in the Z direction. As described above, even if the shape is more easily determined based on the parameter that has a dominant effect on the equivalent diameter instead of the equivalent diameter, the inkjet head 1 can perform stable and stable ink ejection.

  The cross-sectional areas of the supply ink flow path 124a and the discharge ink flow path 124b perpendicular to the X direction are both larger than the cross-sectional areas of the gap 128 perpendicular to the Y direction. As described above, not only the representative value such as the equivalent diameter but also the cross-sectional area is set to be larger on both sides than the gap 128, so that in the ink jet head 1, the flow rate of the ink in the supply ink flow path 124a and the discharge ink flow path 124b is reduced. Thus, the pressure loss in the supply ink flow path 124a and the discharge ink flow path 124b can be further reduced, and on the other hand, an appropriate flow velocity can be generated in the gap 128, so that more effective discharge of bubbles and the like can be performed.

  The inflow port 121 of the supply ink flow path 124a and the outflow port 122 of the discharge ink flow path 124b are provided on different outsides of the arrangement range 1270 in the X direction. This allows the ink flow path to be set diagonally from one end in the longitudinal direction of the supply ink flow path 124a to the other end in the longitudinal direction of the discharge ink flow path 124b. And can be performed stably. Thereby, in the ink jet recording apparatus 100, it is possible to further reduce the unevenness of the pressure loss and to improve the reliability of discharging bubbles and the like.

  The supply ink flow path 124a, the gap 128, and the discharge ink flow path 124b each extend in parallel with the X direction. By arranging the ink jet head 1 efficiently according to the connection position in this way, it is possible to achieve both the ink discharge performance and the discharge performance of bubbles and the like while avoiding an unnecessary increase in the size of the inkjet head 1.

  The lengths in the X direction of the supply ink flow path 124a, the gap 128, and the discharge ink flow path 124b are the same. Thereby, in the ink jet head 1, stagnation in the ink flow and unevenness of the flow velocity are more effectively eliminated, and the uniform and stable ink flow velocity in the X direction makes the pressure loss in each individual flow path 111 uniform. In addition, the reliability of discharge of bubbles and the like can be improved.

In addition, the plurality of individual supply ports 127 are provided on a plurality of arrays extending in the X direction at positions different from each other in the Y direction of the opening surface, and the shape of the discharge ink flow path 124b is the same as the discharge ink flow path It is determined according to the arrangement range of the object closest to 124b.
That is, in the inkjet head 1 having a plurality of nozzle rows (rows of the individual supply ports 127), the shape of the discharge ink flow path 124b is not determined according to the arrangement range 1270 of all the individual supply ports 127, By determining according to the arrangement range of the row on the side of the ink flow path 124b, it is possible to suppress the unnecessary increase of the ink circulation amount as a configuration in which the ink flow path is not expanded more than necessary.

  Further, the shape of the supply ink flow path 124a is determined according to the arrangement range of the arrangement closest to the supply ink flow path 124a in the arrangement. As a result, although the direction of the ink flow is slightly inclined from the Y direction, the increase in the absolute moving distance is very small, and the increase in the unnecessary ink flow path is more effectively performed without substantially affecting the pressure loss. In addition, uniformity of the ink flow can be obtained while suppressing the temperature. Thereby, the inkjet head 1 can perform uniform and stable ink ejection more efficiently.

  Further, the vibration damping section 126 is provided to extend from the surface (upper inner wall surface) opposite to the opening surface in the Z direction in the common flow channel 124 in the direction of the opening surface (−Z direction). The partition wall 125 that separates the path 124a and the discharge ink flow path 124b in the Y direction is provided at an end on the opening surface side. Accordingly, the vibration damping section 126 can be reliably provided at an appropriate position, and the positioning accuracy during manufacturing can be improved and stabilized. Further, since the partition wall 125 achieves both the fixing of the damping section 126 and the separation of the supply ink flow path 124a and the discharge ink flow path 124b, it is possible to efficiently avoid the increase in size and complexity and to reduce the cost.

  Further, the inside of each of the gap 128 and the supply ink flow path 124a (the inside of the discharge ink flow path 124b in the above embodiment) has a hollow shape at least on the opening surface side of the vibration damping unit 126 in the Z direction. . That is, since there is no projection from each wall surface or a support member connecting the wall surfaces is provided, bubbles or foreign matters in the ink are caught by these and are not discharged together with the ink flow. It is possible to prevent air bubbles and the like from stagnating due to obstruction of the flow. In addition, since these structures do not cause unevenness in the ink flow, a more uniform pressure distribution can be obtained.

  Further, the vibration damper 126 is integrally fixed to a surface of the common flow channel 124 facing the opening surface. In other words, there is no need to perform positioning again after the formation of the common flow channel 124 and to provide the vibration damper 126, so that the formation position accuracy can be kept better.

  In addition, the surface of the vibration suppression unit 126 on the side facing the opening surface has a convex shape in a normal state in which the common flow path is filled with ink. Thereby, particularly when the convex surface is directed downward, bubbles and the like remain in depressions and the like near the surface and adversely affect ink supply to the individual flow channel 111 and pressure application to the ink in the individual flow channel 111. Occurrence can be suppressed.

Further, a deaeration port 123 capable of discharging bubbles is provided in the supply ink channel 124a.
That is, the bubbles in the supply ink flow path 124 a can be discharged without passing through the gap 128, and therefore, in the inkjet head 1, when large bubbles pass through the gap 128, there is no adverse effect on the temporary ink ejection. Can be suppressed.

  Further, the inkjet recording apparatus 100 of the present embodiment includes the inkjet head 1 described above. In such an ink jet recording apparatus 100, more stable and uniform ink ejection can be performed.

  In addition, the ink jet recording apparatus 100 has a circulation flow path that allows the ink flowing out of the outlet 122 of the discharge ink flow path 124b to flow again from the inlet 121 of the supply ink flow path 124a, that is, the ink flow path 73, 74, a reflux sub-tank 93 and a liquid feed pump 82. Accordingly, ink discharged without being discharged from the nozzles for discharging bubbles and the like can be effectively used without wasting.

It should be noted that the present invention is not limited to the above embodiment, and various modifications are possible.
For example, in the above-described embodiment, the supply ink flow path 124a and the discharge ink flow path 124b are directly separated by the partition wall 125, but the ink supply unit may include another configuration or structure between these ink flow paths. 12 may be formed.

  Further, in the above embodiment, the supply ink flow path 124a and the discharge ink flow path 124b have been described as having a substantially symmetrical arrangement and shape, but may have different shapes or different positions with respect to the gap 128. It may be provided in a position range different from each other in relation, for example, the Z direction.

  Further, in the above embodiment, the description has been made assuming that three nozzle rows, that is, the rows of the individual supply ports 127 are provided, but the present invention is not limited to this. The row of the individual supply ports 127 may be one row, two rows, four rows, or the like. Further, the individual supply ports 127 do not have to be provided for each row extending in the X direction.

  In the above embodiment, the inflow port 121 is provided at the −X side end of the supply ink flow path 124a, and the outflow port 122 is provided at the + X side end of the discharge ink flow path 124b. May be reversed, or may be provided at other positions, for example, near the center of each of the supply ink flow path 124a and the discharge ink flow path 124b in the X direction.

  Further, the deaeration port 123 does not necessarily have to be provided. In this case, a deaeration path may be provided that is connected to the outlet 122 without passing through the gap 128 from the supply ink flow path 124a as long as the flow of ink flowing through the gap 128 does not have a significant effect. Further, the ink jet head 1 is not limited to the one in which the deaeration port 123 and the outflow port 122 are provided on the same surface.

  In the above embodiment, the lower inner wall surface has the same height at the boundary between the supply ink flow path 124a and the discharge ink flow path 124b and the gap 128, but the present invention is not limited to this. The lower inner wall surface of the supply ink flow path 124a and the discharge ink flow path 124b may be at a position (a position in the −Z direction) lower than the lower inner wall surface of the gap 128 (the height of the individual supply port 127). .

  Further, in the above-described embodiment, the description has been made assuming that the vibration damping section 126 is formed integrally with the common flow path 124 via the partition wall 125. It does not exclude what is retrofitted to or with the partition 125. Alternatively, the vibration damper 126 may be supported and fixed by a support member fixed to another portion of the common flow channel 124 in addition to or instead of the partition 125.

  Further, in the above-described embodiment, the damping section 126 has been described as having a downwardly curved surface, but may have another shape, for example, a planar shape. These may be determined according to the orientation of the vibration damping unit 126 when the inkjet head 1 is attached to the inkjet recording apparatus 100, and the like.

In the above-described embodiment, the description has been made assuming that the ink discharged from the outlet 122 is returned to the supply sub-tank 92 and is reused. However, a configuration in which part or all of the discharged ink is discarded is adopted. There may be.
In addition, specific details such as the specific configuration, shape, positional relationship, and size described in the above embodiment can be appropriately changed without departing from the spirit of the present invention.

REFERENCE SIGNS LIST 1 inkjet head 10 head unit 11 head chip 12 ink supply unit 13 drive control unit 20 transfer units 20a, 20b transfer rollers 20c transfer belts 71 to 74 ink flow paths 81, 82 liquid transfer pump 91 main tank 92 supply sub-tank 93 reflux Sub-tank 100 Ink jet recording device 111 Individual flow path 121 Inflow port 122 Outflow port 123 Deaeration port 124 Common flow path 124a Supply ink flow path 124b Drain ink flow path 125 Partition wall 126 Vibration suppression unit 127 Individual supply port 128 Gap 1270 Positioning range N Opening

Claims (16)

A plurality of individual flow paths for supplying ink to a plurality of nozzles for discharging ink,
A common channel communicating with the plurality of individual channels,
With
The common channel is provided with an inflow portion into which ink flows in from the outside, an outflow portion into which ink flows out, and a plurality of supply ports connected to each of the individual flow channels between the inflow portion and the outflow portion. Including a connection portion,
The connection unit has a vibration damping unit that is provided on a surface opposite to the opening surface provided with the plurality of supply ports and covers an arrangement range of the plurality of supply ports, and suppresses a pressure variation in ink.
The inflow portion and the outflow portion are connected to each other in a second direction perpendicular to the first direction within the opening plane at least in the arrangement range in a first direction along a longitudinal direction of the arrangement range. Connected to different sides of the
In a range including at least the arrangement range with respect to the first direction, a representative length related to a flow path resistance in a cross section perpendicular to the first direction of the inflow portion and the outflow portion is the second length of the connection portion. An ink jet head having a length greater than the representative length related to the flow path resistance in a plane perpendicular to the direction. The representative length of the inflow portion and the outflow portion is a smaller value of a height in a third direction perpendicular to the opening surface of the inflow portion and the outflow portion and a width in the second direction. And
The inkjet head according to claim 1, wherein the representative length of the connection portion is a height of the connection portion in the third direction.   3. The cross-sectional area of the inflow portion and the outflow portion perpendicular to the first direction is larger than the cross-sectional area of the connection portion perpendicular to the second direction. 4. The inkjet head as described in the above.   4. The ink supply device according to claim 1, wherein the ink inlet to the inflow portion and the ink outlet from the outflow portion are provided on different outsides of the arrangement range in the first direction. 5. The inkjet head according to any one of the preceding claims.   The inkjet head according to any one of claims 1 to 4, wherein the inflow portion, the connection portion, and the outflow portion each extend in parallel with the first direction.   The inkjet head according to any one of claims 1 to 5, wherein the inflow portion, the connection portion, and the outflow portion have the same length in the first direction. The plurality of supply ports are provided on a plurality of arrays extending in the first direction at positions different from each other in the second direction of the opening surface,
The shape of the outflow portion is determined according to the arrangement range of the arrangement closest to the outflow portion in the array. The outflow portion according to any one of claims 1 to 6, wherein Inkjet head.   The ink-jet head according to claim 7, wherein the shape of the inflow portion is determined according to the arrangement range of the arrangement closest to the inflow portion in the array.   The vibration damping portion is provided to extend in a direction of the opening surface from a surface opposite to the opening surface in a third direction perpendicular to the opening surface in the common flow channel, and is provided with the inflow portion and the inflow portion. The ink jet head according to claim 1, wherein the ink jet head is provided at an end of the partition wall separating the outflow portion in the second direction on the opening surface side.   10. The ink jet head according to claim 9, wherein the inside of each of the connecting portion and the inflow portion has a hollow shape at least on the opening surface side of the vibration damping portion in the third direction.   The ink jet head according to any one of claims 1 to 10, wherein the vibration damping part is integrally fixed to a surface of the common flow channel facing the opening surface.   The surface on the side opposite to the opening surface of the vibration damping portion has a convex shape in a normal state where the common flow path is filled with ink. The inkjet head as described in the above.   The inkjet head according to claim 1, wherein the inflow portion is provided with a deaeration port capable of discharging air bubbles.   14. The ink jet head according to claim 13, wherein the deaeration port and the ink outlet from the outflow portion open upward in the direction of gravity.   An inkjet recording apparatus comprising the inkjet head according to claim 1.   16. The ink jet recording apparatus according to claim 15, further comprising: a circulation channel that allows the ink flowing out of the outflow portion to flow into the inflow portion again.

Images