JP2020172055A - Liquid discharge head - Google Patents

Abstract

To suppress drying and viscosity increase of the whole of liquid circulating in a liquid discharge head, while maintaining circulation flow rates of liquid required for discharging air bubble.SOLUTION: In a liquid discharge head 3, in a projection shape 43P of a flow path 43 for circulation, a nozzle connection port 43c is arranged between a first communication port 43a and a second communication port 43b in a first direction, where a first distance W1 from one edge to the other edge of the projection shape 43P on a first virtual line V1 parallel to a second direction orthogonal to the first direction which passes through the center of the nozzle connection port 43c is larger than a second distance W2 from the one edge to the other edge of the projection shape 43P on a second virtual line V2 parallel to the second direction which passes through the center of the first communication port 43a, and the first distance W1 is larger than a third distance W3 from the one edge to the other edge of the projection shape 43P on a third virtual line V3 parallel to the second direction which passes through the center of the second communication port 43b.SELECTED DRAWING: Figure 3

Description

The present invention relates to a liquid discharge head that discharges a liquid from a nozzle.

As disclosed in Patent Document 1, as a liquid discharge head for discharging a liquid, a circulation type head for circulating a liquid in a plurality of individual liquid chambers is known. The circulation type head can prevent the liquid in the vicinity of the nozzle from drying by circulating the liquid in the vicinity of the nozzle without retaining the liquid. Further, by circulating the liquid, when air bubbles enter from the nozzle, the air bubbles can be discharged from the circulation type head, and a discharge failure can be prevented.

JP-A-2017-65249

However, the circulating flow rate of the liquid required to prevent the drying of the liquid and the circulating flow rate of the liquid required to discharge the bubbles are not the same. The circulating flow rate of the liquid required for discharging bubbles is, for example, about 20 times larger than the circulating flow rate of the liquid required to prevent the liquid from drying. Therefore, in order to prevent the liquid from drying and to discharge bubbles, it is necessary to circulate the liquid at a large circulation flow rate required for discharging bubbles. Such a large circulation flow rate is an excessive circulation flow rate from the viewpoint of preventing the liquid from drying. Circulation of the liquid at an excessive circulation flow rate can prevent the liquid in the vicinity of the nozzle from drying in the short term. However, in the long run, it dries the entire liquid circulating in the circulating head, causing the liquid to thicken.

An object of the present invention is to provide a liquid discharge head capable of suppressing drying and thickening of the entire liquid circulating in the liquid discharge head while maintaining a circulation flow rate of the liquid required for discharging bubbles.

According to the first aspect of the present invention, it is a liquid discharge head.
A flow path member in which a nozzle arranged along the nozzle surface, an individual flow path connected to the nozzle, and a first and second common flow paths connected to the individual flow path are formed is provided.
The individual flow path
At least one connecting flow path extending along a predetermined direction orthogonal to the nozzle surface and forming a part of a flow path that communicates the first or second common flow path with the nozzle. When,
A first communication port that connects to the connection flow path, extends along a plane orthogonal to the predetermined direction, and communicates with the first common flow path, a second communication port that communicates with the second common flow path, and the nozzle. With a circulation flow path, which has at least one nozzle connection port connected to,
In the projected shape of the circulation flow path projected in the predetermined direction,
The nozzle connection port is arranged between the first communication port and the second communication port in the first direction parallel to the center line connecting the center of the first communication port and the center of the second communication port.
The first distance from one edge of the projected shape to the other edge on the first virtual line that is parallel to the second direction orthogonal to the first direction and passes through the center of the nozzle connection port is parallel to the second direction. It is larger than the second distance from the one edge of the projected shape to the other edge on the second virtual line passing through the center of the first communication port.
The first distance is greater than the third distance from one edge of the projected shape to the other edge of the projected shape on the third virtual line that is parallel to the second direction and passes through the center of the second communication port. Is provided.

According to the second aspect of the present invention, it is a liquid discharge head.
A flow path member in which a nozzle arranged along the nozzle surface, an individual flow path connected to the nozzle, and a first and second common flow paths connected to the individual flow path are formed is provided.
The individual flow path
A connecting flow path that is at least one connecting flow path that extends along a predetermined direction orthogonal to the nozzle surface and that forms a part of a flow path that communicates the first or second common flow path with the nozzle. ,
A first communication port that connects to the connection flow path, extends along a plane orthogonal to the predetermined direction, and communicates with the first common flow path, a second communication port that communicates with the second common flow path, and the nozzle. A circulation flow path having at least one nozzle connection port connected to the
Provided is a liquid discharge head having a bypass flow path that is connected to the circulation flow path, bypasses a part of the liquid flowing in the circulation flow path, and returns the liquid to the circulation flow path again.

It is a schematic block diagram of the printer 1 of 1st Embodiment. It is a top view of the inkjet head 3 which concerns on 1st Embodiment. FIG. 3A is an enlarged view of a portion surrounded by the alternate long and short dash line in FIG. 2, and FIG. 3B is a schematic view of a projected shape 43P in which the connecting flow path 43 of the first embodiment is projected in the vertical direction. Is. FIG. 3 is a sectional view taken along line IV-IV of FIG. 3A. It is a top view of the inkjet head 100 which concerns on 2nd Embodiment. FIG. 5 is a cross-sectional view taken along the line AA of FIG. It is the schematic of the projection shape 123P which projected the connecting flow path 123 of 2nd Embodiment in the vertical direction. It is the schematic of the projection shape 153P which projected the connection flow path 153 of the modification 1 in the vertical direction. It is the schematic of the projection shape 163P which projected the connection flow path 163 of the modification 2 in the vertical direction. It is the schematic of the projection shape 173P which projected the connection flow path 173 of the modification 3 in the vertical direction. It is the schematic of the projection shape 183P which projected the connecting flow path 183 of the modification 4 in the vertical direction. It is the schematic of the projection shape 203P which projected the connection flow path 203 of the modification 5 in the vertical direction. FIG. 13 (a) is a partially enlarged view of a plan view of the inkjet head according to the modified example 6, and FIG. 13 (b) is a projected shape 193P in which the connecting flow path 193 according to the modified example 6 is projected in the vertical direction. It is a schematic diagram of.

[First Embodiment]
The first embodiment will be described below.

<Overall configuration of printer>
As shown in FIG. 1, the printer 1 according to the first embodiment includes a carriage 2, an inkjet head 3 (“liquid ejection head” of the present invention), a platen 4, and transfer rollers 5 and 6.

The carriage 2 is supported by two guide rails 11 and 12 extending in the scanning direction, and moves in the scanning direction along the guide rails 11 and 12. In the following, as shown in FIG. 1, the right side and the left side in the scanning direction are defined and described.

The inkjet head 3 is mounted on the carriage 2 and moves in the scanning direction together with the carriage 2. Further, the inkjet head 3 ejects ink from a plurality of nozzles 45 formed on its lower surface (“nozzle surface” of the present invention). The inkjet head 3 will be described in detail later.

The platen 4 is arranged so as to face the lower surface of the inkjet head 3 and extends over the entire length of the recording paper P in the scanning direction. The platen 4 supports the recording paper P from below. The transport rollers 5 and 6 are arranged on the upstream side and the downstream side of the carriage 2 in the transport direction orthogonal to the scanning direction, respectively, and transport the recording paper P in the transport direction.

Then, in the printer 1, the recording paper P is conveyed by the conveying rollers 5 and 6 by a predetermined distance in the conveying direction, and each time the recording paper P is conveyed, the carriage 2 is moved in the scanning direction, and the inkjet head 3 is used. Printing is performed on the recording paper P by ejecting ink from a plurality of nozzles 45.

<Inkjet head>
Next, the inkjet head 3 will be described in detail. As shown in FIGS. 2 to 4, the inkjet head 3 includes a flow path unit 21 (“flow path member” of the present invention) in which an ink flow path such as a nozzle 45 and a pressure chamber 40 described later is formed, and a pressure chamber. A piezoelectric actuator 22 for applying pressure to the ink in 40 is provided.

<Flower flow unit>
As shown in FIG. 4, the flow path unit 21 (“flow path member” of the present invention) is formed by stacking eight plates 31 to 38 in this order from the top. The flow path unit 21 includes a plurality of pressure chambers 40, a plurality of throttle flow paths 41, a plurality of descender flow paths 42 (“connection flow paths” of the present invention), and a plurality of connection flow paths 43 (“connection flow paths” of the present invention). Circulation flow path "), a plurality of nozzles 45, four supply manifolds 46 ("first common flow path "of the present invention), and three feedback manifolds 47 ("second common flow path "of the present invention). And are formed.

The plurality of pressure chambers 40 are formed in the plate 31. As shown in FIGS. 2 to 4, the pressure chamber 40 has a substantially rectangular planar shape with the scanning direction as the longitudinal direction. That is, the pressure chamber 40 extends along a plane parallel to the scanning direction and the transport direction. The pressure chamber 40 forms a part of the flow path that communicates the supply manifold 46 or the return manifold 47 with the descender flow path 42. Further, the plurality of pressure chambers 40 are arranged in the transport direction to form a pressure chamber row 29. Further, on the plate 31, 12 rows of pressure chamber rows 29 are arranged in the scanning direction. Further, the positions of the pressure chambers 40 in the transport direction are displaced between the pressure chamber rows 29.

As shown in FIG. 4, the plurality of throttle flow paths 41 are formed across the plates 32 and 33. The throttle flow path 41 is individually provided for each pressure chamber 40. The throttle flow path 41 provided for the pressure chamber 40 forming the odd-numbered pressure chamber row 29 from the left is connected to the left end portion of the pressure chamber 40 and extends to the left from the connection portion with the pressure chamber 40. There is. The throttle flow path 41 provided for the pressure chamber 40 forming the even-numbered pressure chamber row 29 from the left is connected to the right end portion of the pressure chamber 40 and extends to the right from the connection portion with the pressure chamber 40. There is.

The plurality of descender flow paths 42 are formed by overlapping through holes 42a to 42f formed in the plates 32 to 37 in the vertical direction (“predetermined direction” of the present invention). The descender flow path 42 is individually provided for each pressure chamber 40. The descender flow path 42 provided for the pressure chamber 40 forming the odd-numbered pressure chamber row 29 from the left is connected to the right end portion of the pressure chamber 40 and extends downward from the connection portion with the pressure chamber 40. .. The descender flow path 42 provided for the pressure chamber 40 forming the even-numbered pressure chamber row 29 from the left is connected to the left end portion of the pressure chamber 40 and extends downward from the connection portion with the pressure chamber 40. ..

The plurality of connecting flow paths 43 are formed in the plate 37. The connecting flow path 43 extends horizontally and in a direction inclined with respect to the scanning direction and the transport direction, and is connected to the pressure chamber 40 constituting one of the two adjacent pressure chamber rows 29. The through hole 42f forming the descender flow path 42 and the through hole 42f forming the descender flow path 42 connected to the pressure chamber 40 forming the other pressure chamber row 29 are connected. In the first embodiment, the plate 37 is formed with a through hole in which a portion serving as a through hole 42f of the two descender flow paths 42 and a portion serving as a connecting flow path 43 are integrated. Further, in the first embodiment, the lower end (lower edge) of the connecting flow path 43 and the lower end (lower edge) of the descender flow path 42 are both formed by the upper surface of the plate 38. As a result, when projected in the extending direction of the connecting flow path 43, the lower edge of the connecting flow path 43 and the lower edge of the descender flow path 42 overlap.

The connecting flow path 43 includes an inflow port 43a (“first communication port” of the present invention) communicating with the supply manifold 46, and an outlet 43b (“second communication port” of the present invention) communicating with the return manifold 47. It has a nozzle connection port 43c that connects to the nozzle 45. The inflow port 43a is connected to the descender flow path 42 (“first connection flow path” of the present invention) and communicates with the supply manifold 46 via the descender flow path 42, the pressure chamber 40, and the throttle flow path 41. The outflow port 43b is connected to the descender flow path 42 (“second connection flow path” of the present invention) and communicates with the return manifold 47 via the descender flow path 42, the pressure chamber 40, and the throttle flow path 41. That is, the descender flow path 42 connected to the inflow port 43a forms at least a part of the flow path that communicates the supply manifold 46 and the nozzle 45. The descender flow path 42 connected to the outflow port 43b forms at least a part of the flow path that communicates the return manifold 47 and the nozzle 45.

The ink flows from the inflow port 43a into the connecting flow path 43, flows from the inflow port 43a toward the outflow port 43b, and flows out from the outflow port 43b. Here, the inflow port 43a and the outflow port 43b are openings formed at the upper end (upper edge) of the connecting flow path 43 by the through holes 42e formed in the plate 36, respectively. In the connecting flow path 43, the thickness of the flow path is not constant, and the central portion connected to the nozzle 45 extends along a plane orthogonal to the vertical direction as compared with both ends connected to the descender flow path 42. ..

In the projected shape 43P in which the connecting flow path 43 is projected in the vertical direction, the direction parallel to the center line m1 connecting the center of the inflow port 43a and the center of the outflow port 43b is the first direction, and the direction perpendicular to the first direction is the first direction. It is defined as the second direction, and each is indicated by an arrow in FIG. 3 (b). As shown in FIG. 3B, the nozzle connection port 43c is arranged between the inflow port 43a and the outflow port 43b in the first direction. Further, the nozzle connection port 43c is arranged on the center line m1. Further, the nozzle connection port 43c is arranged at the center between the inflow port 43a and the outflow port 43b in the first direction. When the shape or area of the connecting flow path 43 changes along the vertical direction, the projected shape 43P obtained by projecting the connecting flow path 43 in the vertical direction is the lower end (lower edge) of the connecting flow path 43. It may be in the shape or the shape of the upper end (upper edge). That is, the projected shape 43P may be a shape formed by the upper surface of the plate 38 of the connecting flow path 43 or a shape formed by the lower surface of the plate 36.

The first edge 43d (“one edge” of the present invention) to the second edge 43e (“one edge”) of the projected shape 43P on the first virtual line V1 parallel to the second direction and passing through the center of the nozzle connection port 43c ( The distance to the "other edge") of the present invention is defined as the first distance W1. The first distance W1 is the width of the projected shape 43P passing through the center of the nozzle connection port 43c in the second direction. The distance from the first edge 43d to the second edge 43e of the projected shape 43P on the second virtual line V2 which is parallel to the second direction and passes through the center of the inflow port 43a is defined as the second distance W2. The second distance W2 is the width of the projected shape 43P passing through the center of the inflow port 43a in the second direction. The distance from the first edge 43d to the second edge 43e of the projected shape 43P on the third virtual line V3 that is parallel to the second direction and passes through the center of the outlet 43b is defined as the third distance W3. The third distance W3 is the width of the projected shape 43P passing through the center of the outlet 43b in the second direction. The first distance W1 is larger than the second distance W2 and the third distance W3 (W1> W2 and W1> W3).

Further, the first distance W1 is the maximum value of the distance from the first edge 43d to the second edge 43e in the second direction of the projected shape 43P of the connecting flow path 43. Further, the first distance W1 is larger than the diameter d2 of the descender flow path 42 (W1> d2). Here, when the diameters of the two descender flow paths 42 are different, and when the diameters change in one descender flow path 42, the first distance W1 is the maximum value d2 of the diameter of the descender flow paths 42. Greater.

The first distance W1 may be 10 times or more the diameter d1 of the nozzle 45 (W1 ≧ 10 · d1). Here, the diameter d1 of the nozzle 45 means the diameter of the opening on the lower surface of the plate 38 of the nozzle 45 formed on the plate 38 (the lower surface of the inkjet head 3, the “nozzle surface” of the present invention). Further, the first distance W1 may be twice or more the second distance W2 or the third distance W3 (W1 ≧ 2 · W2 or W1 ≧ 2 · W3).

In the second direction, the first edge 43d (“one edge” of the present invention) is arranged on one side of the center line m1 and the second edge 43e (“the other edge” of the present invention) on the other side of the center line m1. Edge ") is placed. The first edge 43d and the second edge 43e each include a curve having a center of curvature within the projected shape 43P. In the present embodiment, the radius of curvature of the curve included in the first edge 43d and the radius of curvature of the curve included in the second edge 43e are substantially the same. That is, the projected shape 43P of the connecting flow path 43 is an almond type in which the central portion connected to the nozzle 45 is bulged from both ends connected to the descender flow path 42.

Of the ink flow paths described above, one connecting flow path 43 connected to one nozzle 45, two descender flow paths 42 connected to the connecting flow path 43, and these two descender flow paths 42. The individual flow path 30 is formed by the two pressure chambers 40 connected to the two pressure chambers 40 and the two throttle flow paths 41 connected to the two pressure chambers 40.

The plurality of nozzles 45 are formed on the plate 38. The nozzle 45 is individually provided for each connecting flow path 43, and is connected to the central portion of the connecting flow path 43.

The four supply manifolds 46 are formed by vertically overlapping the through holes formed in the plates 34 and 35 and the recesses formed in the upper portion of the plate 36. Each of the four supply manifolds 46 extends in the transport direction and is arranged at intervals in the scanning direction. The four supply manifolds 46 and the pressure chamber 40 of the throttle flow path 41 connected to the pressure chamber 40 forming the first, fourth, fifth, eighth, ninth, and twelfth pressure chamber rows 29 from the left, respectively. It is connected to the opposite end. Further, an ink supply port 48 is provided at the upstream end of each supply manifold 46 in the transport direction. The ink supply port 48 is connected to an ink tank (not shown), and the ink stored in the ink tank is supplied from the ink supply port 48 to the supply manifold 46. Then, in the supply manifold 46, ink flows from the upstream side to the downstream side in the transport direction, and the ink is supplied to the individual flow path 30 (drawing flow path 41).

The three return manifolds 47 are formed by vertically overlapping through holes formed in the plates 34 and 35 and recesses formed in the upper portion of the plate 36. Each of the three return manifolds 47 extends in the transport direction and is arranged between adjacent supply manifolds 46 in the scanning direction. The three return manifolds 47 are opposite to the pressure chamber 40 of the throttle flow path 41 connected to the pressure chamber 40 forming the second, third, sixth, seventh, tenth, and eleventh pressure chamber rows 29 from the left, respectively. It is connected to the end on the side. Further, an ink discharge port 49 is provided at an upstream end of each return manifold 47 in the transport direction. The ink discharge port 49 is connected to an ink tank (not shown). Then, in the return manifold 47, ink flows from the individual flow path 30 (throttle flow path 41), the ink flows from the downstream side to the upstream side in the transport direction, and the ink flows out from the ink discharge port 49. The ink flowing out from the ink ejection port 49 is returned to an ink tank (not shown). That is, in the first embodiment, ink circulates between the inkjet head 3 and an ink tank (not shown).

Here, a pump (not shown) is provided in the middle of the flow path between the ink supply port 48 and the ink tank, or in the middle of the flow path between the ink discharge port 49 and the ink tank, and the pump is provided. The ink flow caused by being driven causes the ink to circulate as described above.

Further, the plate 37 is formed with a damper chamber 51 that overlaps the supply manifold 46 in the vertical direction and is separated from the supply manifold 46. Then, the pressure fluctuation of the ink in the supply manifold 46 is suppressed by the deformation of the partition wall formed by the lower end portion of the plate 36 that separates the supply manifold 46 and the damper chamber 51. Further, the plate 37 is formed with a damper chamber 52 that overlaps the return manifold 47 in the vertical direction and is separated from the return manifold 47. Then, the pressure fluctuation of the ink in the return manifold 47 is suppressed by the deformation of the partition wall formed by the lower end portion of the plate 36 that separates the return manifold 47 and the damper chamber 52.

<Piezoelectric actuator>
As shown in FIGS. 2 to 4, the piezoelectric actuator 22 has two piezoelectric layers 61 and 62, a common electrode 63, and a plurality of individual electrodes 64. The piezoelectric layers 61 and 62 are made of a piezoelectric material containing lead zirconate titanate (PZT), which is a mixed crystal of lead titanate and lead zirconate, as a main component. The piezoelectric layer 61 is arranged on the upper surface of the flow path unit 21, and the piezoelectric layer 62 is arranged on the upper surface of the piezoelectric layer 61. The piezoelectric layer 61 may be made of an insulating material other than the piezoelectric material, such as a synthetic resin material, unlike the piezoelectric layer 62.

The common electrode 63 is arranged between the piezoelectric layer 61 and the piezoelectric layer 62, and extends continuously over almost the entire area of the piezoelectric layers 61 and 62. The common electrode 63 is held at the ground potential. The plurality of individual electrodes 64 are individually provided for the plurality of pressure chambers 40. The individual electrodes 64 have a substantially rectangular planar shape with the scanning direction as the longitudinal direction, and are arranged so as to overlap the central portion of the corresponding pressure chamber 40 in the vertical direction. Further, the end of the individual electrode 64 opposite to the descender flow path 42 in the scanning direction extends to a position where it does not overlap with the pressure chamber 40, and the tip thereof is a connection terminal 64a for connecting to a wiring member (not shown). It has become. The connection terminals 64a of the plurality of individual electrodes 64 are connected to a driver IC (not shown) via a wiring member (not shown). Then, the ground potential and a predetermined driving potential (for example, about 20 V) are selectively applied to the plurality of individual electrodes 64 individually by the driver IC. Further, corresponding to the arrangement of the common electrode 63 and the plurality of individual electrodes 64 in this manner, the portions of the piezoelectric layer 62 sandwiched between the individual electrodes 64 and the common electrode 63 are respectively located in the thickness direction. It is a polarized active part.

Here, a method of driving the piezoelectric actuator 22 to eject ink from the nozzle 45 will be described. In the piezoelectric actuator 22, all the individual electrodes 64 are held at the same ground potential as the common electrode 63 in the standby state in which ink is not ejected from the nozzle 45. When ink is ejected from a nozzle 45, the potentials of the two individual electrodes 64 corresponding to the two pressure chambers 40 connected to the nozzle 45 are switched from the ground potential to the drive potential.

Then, an electric field parallel to the polarization direction is generated in the two active portions corresponding to the two individual electrodes 64, and the two active portions contract in the horizontal direction orthogonal to the polarization direction. As a result, the portions of the piezoelectric layers 61 and 62 that overlap the two pressure chambers 40 in the vertical direction are deformed so as to be convex toward the pressure chamber 40 as a whole. As a result, as the volume of the pressure chamber 40 becomes smaller, the pressure of the ink in the pressure chamber 40 rises, and the ink is ejected from the nozzle 45 communicating with the pressure chamber 40. Further, after the ink is ejected from the nozzle 45, the potentials of the two individual electrodes 64 are returned to the ground potential. As a result, the piezoelectric layers 61 and 62 return to the state before deformation.

The inkjet head 3 of the present embodiment described above has, for example, the effects described below. As described above, in the circulation type head, if the ink is continuously circulated in an amount that allows the bubbles flowing from the nozzle to be discharged, the entire ink circulating in the inkjet head 3 may be dried, causing thickening of the ink. is there. In the inkjet head 3 of the present embodiment, as shown in FIG. 3B, in the projected shape 43P in which the connecting flow path 43 is projected in the vertical direction, the first distance W1 is from the second distance W2 and the third distance W3. Is also large (W1> W2 and W1> W3). With this configuration, the entire inkjet head 3 can slow down the flow rate of the ink flowing directly above the nozzle connection port 43c, that is, the flow rate of the ink flowing directly above the nozzle 45, while maintaining the circulation flow rate of the ink required for discharging air bubbles. The circulation flow rate of ink can be reduced. As a result, it is possible to suppress drying and thickening of the entire ink circulating in the inkjet head 3 while maintaining the function of discharging air bubbles. Further, by slowing the flow velocity of the ink flowing directly above the nozzle 45, it is possible to prevent the flight direction of the ink droplets ejected from the nozzle 45 from being bent in the direction of the ink flow (flying bend). Further, in the plurality of nozzles 45, by slowing the flow rate of the ink flowing directly above each nozzle 45, the ink directly above the nozzles 45 between the plurality of nozzles 45 due to the position where each nozzle 45 is provided. Non-uniformity (variation) of flow resistance and pressure fluctuation can be reduced. As a result, non-uniformity (variation) in the ejection direction is suppressed among the droplets ejected from the plurality of nozzles 45, and these can be aligned.

The first distance W1 is the maximum value of the distance from the first edge 43d to the second edge 43d in the second direction of the projected shape 43P of the connecting flow path 43. That is, in the second direction, the first distance W1 is the maximum value of the width of the projected shape 43P. With this configuration, the flow velocity of the ink flowing directly above the nozzle 45 can be slowed down.

In the second direction, the first distance W1 is larger than the diameter d2 of the descender flow path 42 (W1> d2). Further, the first distance W1 may be 10 times or more the diameter d1 of the nozzle 45 (W1 ≧ 10 · d1), and may be twice or more the second distance W2 or the third distance W3 (W1). ≧ 2 · W2 or W1 ≧ 2 · W3). By setting the value of the first distance W1 to a range satisfying the above conditions, the size of the first distance W1 can be sufficiently widened, and the flow velocity of the ink flowing directly above the nozzle 45 can be made slower.

Further, in the projected shape 43P, the first edge 43d and the second edge 43e each include a curve having a center of curvature within the projected shape 43P. With this configuration, the projected shape 43P has a shape in which the central portion bulges from the end portion, and the size of the first distance W1 can be sufficiently widened. As a result, the flow velocity of the ink flowing directly above the nozzle 45 can be slowed down.

Further, in the present embodiment, the position of the nozzle 45 with respect to the connecting flow path 43 is the same in all the connecting flow paths 43, but the present embodiment is not limited to this. The position of the nozzle 45 with respect to the connecting flow path 43 may be different among the plurality of connecting flow paths 43. That is, in the plurality of communication flow paths 43, the position where the nozzle connection port 43c in the projection shape 43P of one communication flow path 43 is arranged is the position of the nozzle connection port 43c in the projection shape 43P of the other communication flow path 43. It may be different from the position. The connecting flow path 43 of the present embodiment has a large area of the projected shape 43P projected in the vertical direction. Therefore, in the projected shape 43P, the degree of freedom of the position where the nozzle connection port 43c can be arranged (the position where the nozzle 45 is arranged) is high. Therefore, in the inkjet head 3 of the present embodiment, it is easy to change the design such as changing the nozzle pitch.

[Second Embodiment]
Next, the second embodiment will be described. In the second embodiment, the structure of the inkjet head is different from that in the first embodiment.

As shown in FIGS. 5 to 7, the inkjet head 100 according to the second embodiment includes a flow path unit 101 and a piezoelectric actuator 102.

<Flower flow unit>
The flow path unit 101 is formed by stacking eight plates 111 to 118 in this order from the top. The flow path unit 101 includes a plurality of pressure chambers 120, a plurality of throttle flow paths 121, a plurality of descender flow paths 122 (“connection flow path” of the present invention), a plurality of circulation flow paths 123, and a plurality of circulation flow paths 123. Nozzle 125, six supply manifolds 126 (“first common flow path” of the present invention), and six return manifolds 127 (“second common flow path” of the present invention) are formed.

The plurality of pressure chambers 120 are formed in the plate 111. The pressure chamber 120 has the same shape as the pressure chamber 40 (see FIG. 2). The pressure chamber 120 forms a part of the flow path that communicates the return manifold 127 and the descender flow path 122. Further, the plurality of pressure chambers 120 are arranged in the transport direction to form a pressure chamber row 119. Further, on the plate 111, six rows of pressure chamber rows 119 are arranged in the scanning direction. Further, the positions of the pressure chambers 120 in the transport direction are deviated between the pressure chamber rows 119.

The plurality of throttle flow paths 121 are formed so as to straddle the plates 112 and 113. The throttle flow path 121 has the same shape as the throttle flow path 41 (see FIG. 2), and is individually provided for each pressure chamber 120. The throttle flow path 121 is connected to the left end portion of the pressure chamber 120 and extends to the left from the connection portion with the pressure chamber 120.

The plurality of descender flow paths 122 are formed by overlapping the through holes 122a to 122f formed in the plates 112 to 117 in the vertical direction. The descender flow path 122 is individually provided for each pressure chamber 120. The descender flow path 122 is connected to the right end portion of the pressure chamber 120 and extends downward from the connection portion with the pressure chamber 120.

The plurality of circulation flow paths 123 are formed in the plate 117. The circulation flow path 123 is individually provided with respect to the descender flow path 122, and among the through holes 122a to 122f forming the descender flow path 122, the left lower end portion of the side wall surface of the through hole 122f formed in the plate 117. It extends to the left from the connection portion with the descender flow path 122 (through hole 122f). Further, in the second embodiment, the lower end (lower edge) of the circulation flow path 123 and the lower end (lower edge) of the descender flow path 122 are both formed by the upper surface of the plate 118. As a result, when projected in the scanning direction in which the circulation flow path 123 extends, the lower edge of the circulation flow path 123 and the lower edge of the descender flow path 122 overlap.

The circulation flow path 123 includes an inflow port 123a (“first communication port” of the present invention) communicating with the supply manifold 126 and an outflow port 123b (“second communication port” of the present invention) communicating with the return manifold 127. , Has a nozzle connection port and 123c to connect to the nozzle 125. The inflow port 123a is connected to the supply manifold 126. The outlet 123b connects to the descender flow path 122 and communicates with the return manifold 127 via the descender flow path 122, the pressure chamber 120, and the throttle flow path 121. That is, the descender flow path 122 forms a part of the flow path that communicates the nozzle 125 and the return manifold 127.

The ink flows from the inflow port 123a into the circulation flow path 123, flows from the inflow port 123a toward the outflow port 123b, and flows out from the outflow port 123b. Here, the inflow port 123a is an opening formed by the plate 117 and the plate 118 at the left end of the circulation flow path 123. Further, the outlet 123b is an opening formed at the upper end (upper edge) of the circulation flow path 123 by the through hole 122f formed in the plate 117. In the circulation flow path 123, the thickness of the flow path is not constant, and the central portion connected to the nozzle 125 is orthogonal to the vertical direction as compared with both ends connected to the descender flow path 122 and the supply manifold 126, respectively. It spreads along.

In the projected shape 123P in which the circulation flow path 123 is projected in the vertical direction, the direction parallel to the center line m2 connecting the center of the inflow port 123a and the center of the outflow port 123b is the first direction and perpendicular to the first direction. The direction is defined as the second direction, each of which is indicated by an arrow in FIG. Since the inflow port 123a is open on a plane parallel to the vertical direction, it is represented by a straight line in the projected shape 123P. As shown in FIG. 7, in the first direction, the nozzle connection port 123c is arranged between the inflow port 123a and the outflow port 123b. Further, the nozzle connection port 123c is arranged on the center line m2. Further, the nozzle connection port 123c is arranged at a position closer to the inflow port 123a than the outflow port 123b in the first direction. When the shape or area of the circulation flow path 123 changes along the vertical direction, the projected shape 123P obtained by projecting the circulation flow path 123 in the vertical direction is the lower end (lower side) of the circulation flow path 123. It may be in the shape of an edge) or the shape of the upper end (upper edge). That is, the projected shape 123P may be a shape formed by the upper surface of the plate 118 of the circulation flow path 123 or a shape formed by the lower surface of the plate 117.

The distance from the first edge 123d to the second edge 123e of the projected shape 123P on the first virtual line V11 which is parallel to the second direction and passes through the center of the nozzle connection port 123c is defined as the first distance W11. The first distance W11 is the width of the projected shape 123P passing through the center of the nozzle connection port 123c in the second direction. The distance from the first edge 123d to the second edge 123e of the projected shape 123P on the second virtual line V12 which is parallel to the second direction and passes through the center of the inflow port 123a is defined as the second distance W12. The second distance W12 is the width of the projected shape 123P passing through the center of the inflow port 123a in the second direction. The distance from the first edge 123d to the second edge 123e of the projected shape 123P on the third virtual line V13 that is parallel to the second direction and passes through the center of the outlet 123b is defined as the third distance W13. The third distance W13 is the width of the projected shape 123P passing through the center of the outlet 123b in the second direction. The first distance W11 is larger than the second distance W12 and the third distance W13 (W11> W12 and W11> W13).

Further, the first distance W11 is the maximum value of the distance from the first edge 123d to the second edge 123e in the second direction of the projected shape 123P of the circulation flow path 123. Further, the first distance W11 is larger than the diameter d12 of the descender flow path 122 (W11> d12). Here, when the diameter of the descender flow path 122 changes, the first distance W11 is larger than the maximum value d12 of the diameter of the descender flow path 122.

The first distance W11 may be 10 times or more the diameter d11 of the nozzle 125 (W11 ≧ 10 · d11). Here, the diameter d11 of the nozzle 125 means the diameter of the opening on the lower surface of the plate 118 of the nozzle 125 formed on the plate 118 (the lower surface of the inkjet head 3, the “nozzle surface” of the present invention). Further, the first distance W11 may be twice or more the second distance W12 or the third distance W13 (W11 ≧ 2 · W12 or W11 ≧ 2 · W13).

In the second direction, the first edge 123d is arranged on one side of the center line m2, and the second edge 123e is arranged on the other side of the center line m2. The first edge 123d and the second edge 123e each include a curve having a center of curvature within the projected shape 123P. In the present embodiment, the radius of curvature of the curve included in the first edge 123d and the radius of curvature of the curve included in the second edge 123e are substantially the same. That is, the projected shape 123P of the connecting flow path 123 has a shape in which the central portion connected to the nozzle 125 is bulged from both ends connected to the descender flow path 122 and the supply manifold 126, respectively.

The individual flow path 110 is formed by the descender flow path 122, the circulation flow path 123 and the pressure chamber 120 connected to the descender flow path 122, and the throttle flow path 121 connected to the pressure chamber 120. Further, the individual flow path rows 109 are formed by arranging the plurality of individual flow paths 110 in the transport direction. Further, in the flow path unit 101, six rows of individual flow path rows 109 are arranged in the scanning direction.

The plurality of nozzles 125 are formed on the plate 118. The nozzle 125 is individually provided with respect to the circulation flow path 123.

The six supply manifolds 126 are formed on the plate 117. Each of the six supply manifolds 126 extends in the transport direction and is spaced apart in the scanning direction. The six supply manifolds 126 correspond to the six rows of individual flow paths 109, and each supply manifold 126 has a circulation flow path 123 of a plurality of individual flow paths 110 constituting the corresponding individual flow path rows 109. It is connected. Further, each supply manifold 126 is inclined to the right side in the scanning direction and extends in a portion on the upstream side in the transport direction with respect to the individual flow path row 109. An ink supply port 128 is provided at an upstream end of each supply manifold 126 in the transport direction. Then, the ink stored in the ink tank (not shown) is supplied to the supply manifold 126 from the ink supply port 128. As a result, in the supply manifold 126, the ink flows from the upstream side to the downstream side in the transport direction, and the ink is supplied to the individual flow path 110 (circulation flow path 123).

The six return manifolds 127 are formed on the plate 114. Each of the six feedback manifolds 127 extends in the transport direction and is spaced apart in the scanning direction. The return manifold 127 is located above the supply manifold 126 and overlaps the supply manifold 126 in the vertical direction. Further, the six return manifolds 127 correspond to the six rows of individual flow path rows 109, and each feedback manifold 127 corresponds to the throttle flow paths 121 of the plurality of individual flow paths 110 constituting the corresponding individual flow path rows 109. Is connected to. Further, each feedback manifold 127 extends so as to be inclined to the left side in the scanning direction in a portion on the upstream side in the transport direction with respect to the individual flow path row 109. Further, an ink discharge port 129 is provided at the upstream end of each return manifold 127 in the transport direction. An ink tank (not shown) is connected to the ink discharge port 129. Then, in the return manifold 127, ink flows from the individual flow path 110 (throttle flow path 121), the ink flows from the downstream side to the upstream side in the transport direction, and the ink flows out from the ink discharge port 129. The ink flowing out from the ink discharge port 129 is returned to an ink tank (not shown). That is, in the second embodiment, ink circulates between the inkjet head 100 and an ink tank (not shown).

Here, a pump (not shown) is provided in the middle of the flow path between the ink supply port 128 and the ink tank, or in the middle of the flow path between the ink discharge port 129 and the ink tank, and the pump is provided. The ink flow caused by being driven causes the ink to circulate as described above.

Further, the flow path unit 101 is formed with a damper chamber 130 that extends over a lower portion of the plate 115 and an upper portion of the plate 116 and overlaps the supply manifold 126 and the return manifold 127 in the vertical direction. Then, the pressure fluctuation of the ink in the supply manifold 126 is suppressed by the deformation of the partition wall formed by the lower end portion of the plate 116 that separates the supply manifold 126 and the damper chamber 130. Further, the pressure fluctuation of the ink in the return manifold 127 is suppressed by the deformation of the partition wall formed by the upper end portion of the plate 115 that separates the return manifold 127 and the damper chamber 130.

<Piezoelectric actuator>
The piezoelectric actuator 102 has two piezoelectric layers 141 and 142, a common electrode 143, and a plurality of individual electrodes 144. The piezoelectric layers 141 and 142 are made of a piezoelectric material. The piezoelectric layer 141 is arranged on the upper surface of the flow path unit 101, and the piezoelectric layer 142 is arranged on the upper surface of the piezoelectric layer 141. The piezoelectric layer 141 may be made of an insulating material other than the piezoelectric material, like the piezoelectric layer 61.

The common electrode 143 is arranged between the piezoelectric layer 141 and the piezoelectric layer 142, and extends continuously over the entire area of the piezoelectric layers 141 and 142. The common electrode 143 is held at the ground potential. The plurality of individual electrodes 144 are individually provided for the plurality of pressure chambers 120. The individual electrode 144 has a substantially rectangular planar shape similar to that of the individual electrode 64, and is arranged so as to overlap the central portion of the corresponding pressure chamber 120 in the vertical direction. The connection terminals 144a of the plurality of individual electrodes 144 are connected to a driver IC (not shown) via a wiring member (not shown). Then, one of the ground potential and the driving potential is selectively applied to the plurality of individual electrodes 144 individually by the driver IC. Further, corresponding to the arrangement of the common electrode 143 and the plurality of individual electrodes 144 in this manner, the portions of the piezoelectric layer 142 sandwiched between the individual electrodes 144 and the common electrode 143 are respectively located in the thickness direction. It is a polarized active part.

Here, a method of driving the piezoelectric actuator 102 to eject ink from the nozzle 125 will be described. In the piezoelectric actuator 102, all the individual electrodes 144 are held at the same ground potential as the common electrode 143 in the standby state in which ink is not ejected from the nozzle 125. When ink is ejected from a certain nozzle 125, the potential of the individual electrode 144 corresponding to the nozzle 125 is switched from the ground potential to the drive potential.

Then, as described in the first embodiment, the portions of the piezoelectric layers 141 and 142 that overlap the pressure chamber 120 in the vertical direction are deformed so as to be convex toward the pressure chamber 120 as a whole. As a result, the volume of the pressure chamber 120 becomes smaller, so that the pressure of the ink in the pressure chamber 120 rises, and the ink is ejected from the nozzle 125 communicating with the pressure chamber 120. Further, after the ink is ejected from the nozzle 125, the potential of the individual electrode 144 is returned to the ground potential.

In the inkjet head 100 of the present embodiment described above, similarly to the first embodiment, in the projection shape 123P in which the circulation flow path 123 is projected in the vertical direction, the first distance W11 is the second distance W12 and the third distance. Greater than W13 (W11> W12 and W11> W13). The inkjet head 100 of the present embodiment has the same effect as the inkjet head 3 of the first embodiment.

In the circulation flow path 123 of the inkjet head 100, ink flows from the inflow port 123a (the "first communication port" of the present invention) to the outflow port 123b (the "second communication port" of the present invention). For example, when the ink flows in the opposite direction, that is, when the ink flows from the outlet 123b (“second communication port” of the present invention) to the inlet 123a (“first communication port” of the present invention). However, the inkjet head 100 of the present embodiment has the same effect. When ink flows in the opposite direction, for example, in the vertical direction, from the feedback manifold 127 (“second common flow path” of the present invention) arranged on the upper side, the supply manifold 126 arranged on the lower side. This is the case where the ink flows toward (the "first common flow path" of the present invention).

[Modifications 1 to 5]
In the inkjet heads according to the modifications 1 to 5, the connecting flow paths 43 (see FIG. 3) of the inkjet head 3 according to the first embodiment are linked to the connecting flow paths 153, 163, 173, 183 and FIGS. This is a modified example replaced with 203. Other configurations are the same as those of the inkjet head 3 according to the first embodiment. In FIGS. 8 to 12, the same reference numbers are used for the same components as in the first embodiment. In the inkjet heads according to the modifications 1 to 5 described below, the first distance W1 is the second distance W2 and the third distance in the projected shape in which the connecting flow path is projected in the vertical direction, as in the first embodiment. Greater than W3 (W1> W2 and W1> W3). The inkjet heads according to the modified examples 1 to 5 have the same effects as those in the first embodiment.

In the first modification, as shown in FIG. 8, at least one pillar 154 extending in the vertical direction is provided in the connecting flow path 153. Specifically, in the modified example 1, four columns 154 are provided. The pillar 154 extends in the vertical direction to connect the plate 38 and the plate 36. The central portion of the connecting flow path 153 extends along a plane orthogonal to the vertical direction, but by having the pillar 154 inside, it is possible to prevent a decrease in mechanical strength.

In the first embodiment described above, in the projected shape 43P in which the connecting flow path 43 is projected in the vertical direction, the nozzle connection port 43c is arranged on the center line m1 (see FIG. 3B), but the first The embodiment is not limited to this. The nozzle connection port 43c may be arranged at a position deviating from the center line m1. Further, the nozzle connection port 43c may be arranged on the first virtual line V1 at a position closer to the first edge 43d or the second edge 43e than the center line m1. In the second modification, as shown in FIG. 9, the nozzle connection port 43c is arranged at a position deviated from the center line m1 in the projected shape 163P in which the connecting flow path 163 is projected in the vertical direction. Further, the nozzle connection port 43c is arranged on the first virtual line V1 at a position closer to the first edge 43c than the center line m1. The flow velocity of the ink flowing in the connecting flow path 163 is slower at a position deviated from the center line m1 than at a flow velocity on the center line m1. Therefore, by arranging the nozzle connection port 43c at a position deviating from the center line m1, the flow velocity of the ink flowing directly above the nozzle 45 can be made slower.

In the first embodiment described above, in the projected shape 43P in which the connecting flow path 43 is projected in the vertical direction, the radius of curvature of the curve included in the first edge 43d and the radius of curvature of the curve included in the second edge 43e are approximately the same. Although they are the same (see FIG. 3B), the first embodiment is not limited to this. In the third modification, as shown in FIG. 10, in the projected shape 173P in which the connecting flow path 173 is projected in the vertical direction, the radius of curvature of the curve included in the first edge 43d is the curvature of the curve 43e included in the second edge. Smaller than the radius. The nozzle connection port 43c is arranged at a position closer to the first edge 43d than the second edge 43e. The flow velocity of the ink flowing in the connecting flow path 173 becomes slow near the first edge 43d, which is smaller than the radius of curvature. Therefore, by arranging the nozzle connection port 43c in the vicinity of the first edge 43d, the flow velocity of the ink flowing directly above the nozzle 45 can be made slower.

In the first embodiment described above, one nozzle connection port 43c is formed in the connection flow path 43 (see FIG. 3B). That is, one nozzle 45 corresponds to one connecting flow path 43. However, the first embodiment is not limited to this. In the modified example 4, as shown in FIG. 11, a plurality of nozzle connection ports 43c, specifically two nozzle connection ports 43c, are formed in the connecting flow path 183. That is, two nozzles 45 correspond to one connecting flow path 183. With this configuration, the amount of ink droplets ejected from each nozzle 45 can be reduced, and a fine image can be printed.

In the first embodiment described above, the connecting flow path 43 extends along a first direction, that is, a direction parallel to the center line m1 (see FIG. 3B). Therefore, in the second direction, the first edge 43d is arranged on one side of the center line m1, and the second edge 43e is arranged on the other side of the center line m1. The center line m1 is arranged between the first edge 43d and the second edge 43e in the second direction. From the center of the inflow port 43a to the center of the outflow port 43b, the center line m1 is arranged in the projected shape 43P. Between the center of the inflow port 43a and the center of the outflow port 43b, the center line m1 does not intersect the first edge 43d and the second edge 43e. However, the first embodiment is not limited to this. In the modified example 5, as shown in FIG. 12, the connecting flow path 203 is curved with respect to the center line m1. Therefore, in the central portion (near the nozzle connection port 43c) of the projected shape 203P of the connecting flow path 203, the center line m1 is arranged between the first edge 43d and the second edge 43e in the second direction. Not. In the central portion of the projected shape 203P, in the second direction, both the first edge 43d and the second edge 43e are arranged on the other side of the center line m1. Further, at both ends of the projected shape 203P of the connecting flow path 203 (near the inflow port 43a and near the outflow port 43b), the center line m1 is arranged in the projected shape 43P, but the central portion of the projected shape 203P (nozzle connection port). In the vicinity of 43c), the center line m1 is arranged outside the projected shape 43P. That is, the center line m1 intersects the first edge 43d between the center of the inflow port 43a and the center of the outflow port 43b. In the fifth modification, the flow velocity of the ink flowing directly above the nozzle 45 can be made slower by bending the connecting flow path 203 with respect to the center line m1.

[Modification 6]
In the inkjet head according to the sixth modification, the connection flow path 43 (see FIGS. 3 (a) and 3 (b)) of the inkjet head 3 according to the first embodiment is bypassed as shown in FIGS. 13 (a) and 13 (b). This is a modified example in which the connecting flow path 193 to which the road 194 is connected is replaced. Other configurations are the same as those of the inkjet head 3 according to the first embodiment. In FIGS. 13A and 13B, the same reference numbers are used for the same components as in the first embodiment.

The bypass flow path 194 is formed on the plate 37 (see FIG. 4) in the same manner as the connecting flow path 193. Both ends of the bypass flow path 194 are connected to the connecting flow path 193. One bypass flow path 194 may be provided in one connecting flow path 193, or a plurality of bypass flow paths 194 may be provided. In the modification 6, two bypass flow paths 194 are provided in one connection flow path 193. In the projected shape 193P in which the connecting flow path 193 is projected in the vertical direction shown in FIG. 13B, both ends of the bypass flow path 194a are connected to the first edge 43d located on one side of the center line m1 and the center line is connected. Both ends of the bypass flow path 194b are connected to the second edge 43e located on the other side of m1. In the first direction, the nozzle 43c and the nozzle 45 are arranged between both ends of the bypass flow path 194a. Similarly, in the first direction, the nozzle 43c and the nozzle 45 are arranged between both ends of the bypass flow path 194b.

In the modified example 6, a part of the ink flowing in the connecting flow path 193 flows into the bypass flow path 194 and returns to the connecting flow path 193 again. That is, the bypass flow path 194 bypasses a part of the ink flowing in the connecting flow path 193 and returns to the connecting flow path 193 again. With this configuration, the flow rate of ink directly above the nozzle connection port 43c can be reduced. As a result, the flow velocity of the ink flowing directly above the nozzle connection port 43c, that is, the flow velocity of the ink flowing directly above the nozzle 45 can be slowed down. As a result, in the modified example 6, the drying and thickening of the entire ink circulating in the inkjet head 3 can be suppressed while maintaining the function of discharging air bubbles, as in the first embodiment. Further, as in the first embodiment, the flight bending of the ink droplets ejected from the nozzle 45 can be suppressed, and the non-uniformity (variation) in the ejection direction can be suppressed among the droplets ejected from the plurality of nozzles 45. , These can be arranged.

In the sixth modification, unlike the first embodiment, the first distance W1 does not have to be larger than the second distance W2 and the third distance W3. For example, the distance W1, the distance W2, and the distance W3 may be the same (W1 = W2 = W3). In the sixth modification, even if the magnitude relation of the distance W1, the distance W2, and the distance W3 is different from that of the first embodiment, the connecting flow path 193 to which the bypass flow path 194 is connected provides the same effect as that of the first embodiment. Play.

Modifications 1 to 6 of the first embodiment described above can also be applied to the second embodiment. Further, the configurations of the connecting flow paths 153, 163, 173, 183, 203 and 193 shown in FIGS. 8 to 13 described in the modified examples 1 to 6 can be appropriately combined.

[Modification 7]
Modification 7 is an example of a so-called share mode type inkjet head. For example, the circulation type inkjet head disclosed in Japanese Patent Application Laid-Open No. 2018-103557 has a discharge channel extending in the vertical direction (“connection flow path” of the present invention) and a circulating flow extending in the vertical direction in the circulation type inkjet head. A path (“connecting flow path” of the present invention) and a return flow path extending in the horizontal direction, connecting the lower end of the discharge channel and the lower end of the circulation flow path, and connecting to the nozzle are formed. (See FIG. 8 of JP-A-2018-103557). In the inkjet head of JP-A-2018-103557, the ink flows from the ejection channel to the circulation channel through the return channel and circulates. Further, the wall surface of the discharge channel is deformed by applying a voltage, and the volume thereof increases or decreases. The inkjet head of Japanese Patent Application Laid-Open No. 2018-103557 ejects ink from a nozzle by increasing or decreasing the volume of the ejection channel.

In the modified example 7, the return flow path of the inkjet head disclosed in Japanese Patent Application Laid-Open No. 2018-103557 is replaced with the connection flow path 43 of the first embodiment shown in FIG. 3 (b). As a result, in the modified example 7, the same effect as that of the first embodiment can be obtained in the share mode type inkjet head.

Although the embodiments and modifications have been described above, the present invention is not limited to the above examples, and various modifications can be made as long as they are described in the claims.

Further, in the above, an example in which the present invention is applied to an inkjet head that ejects ink from a nozzle has been described, but the present invention is not limited to this. It is also possible to apply the present invention to a liquid ejection head other than an inkjet head that ejects a liquid other than ink.

3 Inkjet head 30 Individual flow path 31 to 33 Plate 40 Pressure chamber 42 Descender flow path 42a, 42b Through hole 43 Connection flow path 45 Nozzle 46 Supply manifold 47 Return manifold 100 Inkjet head 110 Individual flow path 111-113 Plate 120 Pressure chamber 122 Descender flow path 122a, 122b Through hole 123 Circulation flow path 125 Nozzle 126 Supply manifold 127 Return manifold

Claims (17)

It is a liquid discharge head
A flow path member in which a nozzle arranged along the nozzle surface, an individual flow path connected to the nozzle, and a first and second common flow paths connected to the individual flow path are formed is provided.
The individual flow path
At least one connecting flow path extending along a predetermined direction orthogonal to the nozzle surface and forming a part of a flow path that communicates the first or second common flow path with the nozzle. When,
A first communication port that connects to the connection flow path, extends along a plane orthogonal to the predetermined direction, and communicates with the first common flow path, a second communication port that communicates with the second common flow path, and the nozzle. With a circulation flow path, which has at least one nozzle connection port connected to,
In the projected shape of the circulation flow path projected in the predetermined direction,
The nozzle connection port is arranged between the first communication port and the second communication port in the first direction parallel to the center line connecting the center of the first communication port and the center of the second communication port.
The first distance from one edge of the projected shape to the other edge on the first virtual line that is parallel to the second direction orthogonal to the first direction and passes through the center of the nozzle connection port is parallel to the second direction. It is larger than the second distance from the one edge of the projected shape to the other edge on the second virtual line passing through the center of the first communication port.
The first distance is greater than the third distance from one edge of the projected shape to the other edge of the projected shape on the third virtual line that is parallel to the second direction and passes through the center of the second communication port. .. The liquid discharge head according to claim 1, wherein the first distance is the maximum value of the distance from the one edge to the other edge in the second direction of the projected shape of the circulation flow path. The liquid discharge head according to claim 1 or 2, wherein at least one pillar extending in the predetermined direction is provided in the circulation flow path. The liquid discharge head according to any one of claims 1 to 3, wherein the nozzle connection port is arranged on the center line in the projected shape of the circulation flow path. The liquid discharge head according to any one of claims 1 to 3, wherein the nozzle connection port is arranged at a position deviated from the center line in the projected shape of the circulation flow path. According to claim 5, in the projected shape of the circulation flow path, the nozzle connection port is arranged on the first virtual line at a position closer to the one edge or the other edge than the center line. The liquid discharge head described. In the projected shape of the circulation flow path,
In the second direction, the one edge is arranged on one side of the center line and the other edge is arranged on the other side.
The liquid discharge head according to any one of claims 1 to 3, wherein each of the one edge and the other edge includes a curve having a center of curvature in the projected shape. In the projected shape of the circulation flow path,
The radius of curvature of the curve included by the one edge is smaller than the radius of curvature of the curve included by the other edge.
The liquid discharge head according to claim 7, wherein the nozzle connection port is arranged at a position closer to the one edge than the other edge on the first virtual line. The liquid discharge head according to any one of claims 1 to 8, wherein two nozzle connection ports are formed in the circulation flow path. The flow path member is formed with a plurality of the nozzles, a plurality of the individual flow paths, and a plurality of first and second manifolds.
The position where the nozzle connection port is arranged in the projected shape projected in the predetermined direction of one of the circulation flow paths of the plurality of individual flow paths is
Any one of claims 1 to 9, which is different from the position of the nozzle connection port in the projected shape projected in the predetermined direction of the other one of the circulation flow paths of the plurality of individual flow paths. The liquid discharge head according to the section. The liquid discharge head according to any one of claims 1 to 10, wherein the first distance is larger than the diameter of the connection flow path. The connection flow path
A first connection flow path that forms at least a part of the flow path that communicates the first common flow path and the nozzle.
Includes a second connecting flow path that forms at least a portion of the flow path that communicates the second common flow path with the nozzle.
The liquid according to any one of claims 1 to 11, wherein in the circulation flow path, the first connection flow path is connected to the first communication port and the second connection flow path is connected to the second communication port. Discharge head. In the circulation flow path, the first common flow path is connected to the first communication port, and the connection flow path is connected to the second communication port.
The liquid discharge head according to any one of claims 1 to 11, wherein the connecting flow path forms a part of a flow path that connects the nozzle and the second common flow path. The individual flow path further has at least one pressure chamber.
The liquid discharge head according to any one of claims 1 to 13, wherein the pressure chamber forms a part of a flow path that communicates the first or second common flow path with the connection flow path. The liquid discharge head according to any one of claims 1 to 14, wherein the first distance is 10 times or more the diameter of the nozzle. The liquid discharge head according to any one of claims 1 to 15, wherein the first distance is at least twice the second distance or the third distance. It is a liquid discharge head
A flow path member in which a nozzle arranged along the nozzle surface, an individual flow path connected to the nozzle, and a first and second common flow paths connected to the individual flow path are formed is provided.
The individual flow path
A connecting flow path that is at least one connecting flow path that extends along a predetermined direction orthogonal to the nozzle surface and that forms a part of a flow path that communicates the first or second common flow path with the nozzle. ,
A first communication port that connects to the connection flow path, extends along a plane orthogonal to the predetermined direction, and communicates with the first common flow path, a second communication port that communicates with the second common flow path, and the nozzle. A circulation flow path having at least one nozzle connection port connected to the
A liquid discharge head having a bypass flow path connected to the circulation flow path, bypassing a part of the liquid flowing in the circulation flow path, and returning the liquid to the circulation flow path again.

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