Liquid ejection head

Abstract

To surely remove thickened ink from an end part of a nozzle.SOLUTION: A liquid discharge head comprises a plurality of individual channels to which ink is supplied from a supply manifold, and which return some of the supplied ink to a return manifold. The plurality of individual channels each have a pressure chamber, a nozzle 21 that discharges the ink, a connection channel 23 that connects the pressure chamber and the nozzle 21, and an outflow channel 25 connected to the return manifold. The connection channel 23 is composed of a first channel 23a to which the nozzle 21 is connected in the middle thereof, and a second channel 23b that is separated from the nozzle 21 with respect to a scanning direction, and connects the pressure chamber 22 and the first channel 23a. The outflow channel 25 is connected to the first channel 23a on the opposite side to the second channel 23b across the nozzle 21 with respect to the scanning direction. The first channel 23a bends to swell on one side of a conveyance direction orthogonal to the scanning direction, and a flowing direction of the ink flowing in the first channel 23a bends to swell on one side of the conveyance direction.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to a liquid ejection head that ejects liquid from a nozzle. [Background technology]

[0002] As an example of a liquid ejection head that ejects liquid from nozzles, Patent Document 1 describes an inkjet recording head that ejects ink from nozzles. The inkjet recording head of Patent Document 1 has individual flow paths having pressure chambers that communicate with each of the nozzles, and a first common liquid chamber that is provided in common to the individual flow paths and supplies ink to the individual flow paths. Then, a piezoelectric actuator causes a pressure change in the ink in the pressure chamber, thereby ejecting ink droplets from the nozzles.

[0003] Moreover, the ink jet recording head of Patent Document 1 has a second common liquid chamber that is provided in common to the multiple individual flow paths and into which ink from the multiple individual flow paths flows in. Then, ink can be sent from the first common liquid chamber to the second common liquid chamber via the individual flow paths, thereby circulating the ink within the head.

[0004] The individual flow paths have a first flow path with a nozzle disposed midway and extending in a first direction, which is an in-plane direction of the nozzle face, a second flow path connecting the pressure chamber and the first flow path, and a third flow path connected to the first flow path on the opposite side of the nozzle to the second flow path in the first direction. Ink circulating inside the head generates an ink flow in the first flow path along the first direction, which is an in-plane direction of the nozzle face. This ink flow can remove air bubbles that have entered through the nozzle and viscous ink that has dried due to the nozzle, and discharge them from the individual flow paths to the second common liquid chamber side. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2020-10055 A Summary of the Invention [Problem to be solved by the invention]

[0006] In the above-mentioned ink jet recording head, the first flow path in which the nozzle is disposed extends linearly along the first direction. Therefore, the flow of ink generated in the first flow path is linear along the first direction. At this time, the flow speed of the ink is the largest at the center in the width direction of the first flow path and decreases toward the ends in the width direction. Therefore, the thickened ink at the ends of the nozzle cannot be sufficiently removed.

[0007] An object of the present invention is to provide a liquid ejection head that can reliably remove viscous ink from the ends of the nozzles. [Means for solving the problem]

[0008] The liquid ejection head of the present invention includes a plurality of individual flow paths, a first common liquid chamber provided in common to the plurality of individual flow paths and supplying liquid to the plurality of individual flow paths, and a second common liquid chamber provided in common to the plurality of individual flow paths and into which liquid from the plurality of individual flow paths flows. Each of the plurality of individual flow paths includes a pressure chamber, a nozzle for ejecting liquid, a first flow path to which the nozzle is connected, a second flow path that is separated from the nozzle in a first direction along a nozzle face in which the nozzle opens and connects the pressure chamber and the first flow path, and a third flow path that is connected to the first flow path on the opposite side to the second flow path with the nozzle sandwiched between them in the first direction. The first flow path is curved so as to bulge toward one side in a second direction that is along the nozzle face and perpendicular to the first direction, and the flow direction of the liquid flowing in the first flow path is curved so as to bulge toward one side in the second direction. Effect of the Invention

[0009] According to the liquid ejection head of the present invention, the flow direction of the liquid in the first flow path is bent so as to bulge to one side in the second direction, so that the flow speed of the liquid at the end of the first flow path on one side in the second direction can be increased compared to when the flow direction of the liquid in the first flow path is linear, and therefore thickened ink at the end of the nozzle connected to the first flow path can be reliably removed. [Brief description of the drawings]

[0010] [Figure 1] 1 is a plan view of a printer equipped with an inkjet head according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a plan view of the inkjet head shown in FIG. [Diagram 3] 3 is a cross-sectional view of the inkjet head taken along line III-III in FIG. 2. [Figure 4] 4 is a cross-sectional view of the inkjet head taken along line IV-IV in FIG. 2. [Diagram 5] FIG. 4 is a diagram for explaining the shape of the connection flow path shown in FIG. [Figure 6] 4 is a plan view of a plate in which a first flow path of the connecting flow path shown in FIG. 3 is formed. FIG. [Figure 7] FIG. 4 is a diagram showing a connecting flow path according to a first modified example of the present invention. [Figure 8] FIG. 11 is a diagram showing a connecting flow path according to a second modified example of the present invention. [Figure 9] FIG. 13 is a diagram showing a connecting flow path according to a third modified example of the present invention. [Figure 10] FIG. 13 is a plan view of a plate in which a first flow path of a connecting flow path is formed according to a fourth modified example of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] A preferred embodiment of the present invention will now be described.

[0012] <Overall printer configuration> As shown in FIG. 1, a printer 100 according to this embodiment includes an inkjet head 1 ("liquid ejection head" of the present invention), a carriage 2, guide rails 3a and 3b, a platen 4, transport rollers 5a and 5b, and an ink tank 6.

[0013] The carriage 2 is supported by two guide rails 3a, 3b that extend in a horizontal scanning direction (left-right direction in FIG. 1), and moves in the scanning direction along the guide rails 3a, 3b. The inkjet head 1 is mounted on the carriage 2, and moves in the scanning direction together with the carriage 2. In the following description, the right side of FIG. 1 in the scanning direction is referred to as "one side," and the left side of FIG. 1 is referred to as "the other side."

[0014] Ink of four colors, black, yellow, cyan, and magenta, is supplied to the inkjet head 1 from an ink tank 6 via a pipe (not shown). The inkjet head 1 ejects ink from a plurality of nozzles 21 formed on a nozzle surface 11y (see FIGS. 3 and 4), which is its lower surface.

[0015] The multiple nozzles 21 form a nozzle row 21a along a transport direction (a direction from bottom to top in FIG. 1) that is perpendicular to the scanning direction in a plan view. The inkjet head 1 has four nozzle rows 21a aligned in the scanning direction. The multiple nozzles 21 eject black, yellow, cyan, and magenta inks in that order, starting from the nozzles constituting the nozzle row 21a located at the rightmost position in the scanning direction in FIG. 1. The inkjet head 1 will be described in detail later.

[0016] The platen 4 is disposed opposite the nozzle surface 11y, which is the lower surface of the inkjet head 1, and extends in the scanning direction over the entire length of the recording paper P. The platen 4 supports the recording paper P from below. The transport rollers 5a, 5b are disposed respectively upstream and downstream of the carriage 2 in the transport direction, and transport the recording paper P in the transport direction.

[0017] The printer 100 performs printing on the recording paper P by alternately performing a conveying process in which the recording paper P is conveyed a predetermined distance at a time in the conveying direction by the conveying rollers 5a and 5b, and a scanning process in which ink is ejected from the multiple nozzles 21 of the inkjet head 1 while the carriage 2 is moved in the scanning direction. In other words, the printer 100 is a serial type. In the following description, the direction perpendicular to both the scanning direction and the conveying direction is defined as the up-down direction.

[0018] <Inkjet head 1> Next, the detailed configuration of the inkjet head 1 will be described with reference to Figs. 2 to 4. The scanning direction corresponds to the "first direction" of the present invention, the transport direction corresponds to the "second direction" of the present invention, and the up-down direction corresponds to the "third direction" of the present invention. As shown in Fig. 2, the inkjet head 1 has a rectangular shape that is elongated in the transport direction when viewed from above. The inkjet head 1 includes a flow path unit 11 and a piezoelectric actuator 12.

[0019] As shown in Figures 3 and 4, the flow path unit 11 is composed of eleven plates 11a to 11k that are stacked vertically and bonded to each other. A plurality of individual flow paths 20, a supply manifold 31 (a "first common liquid chamber" of the present invention), a return manifold 32 (a "second common liquid chamber" of the present invention), and a connecting flow path 33 are formed in the flow path unit 11. Note that the individual flow paths 20 are not shown in Figure 2. Through holes and recesses that constitute the individual flow paths 20, the supply manifold 31, the return manifold 32, and the connecting flow path 33 are formed in each of the plates 11a to 11k.

[0020] As shown in Fig. 2, four each of the supply manifolds 31 and the return manifolds 32 are formed. The supply manifolds 31 and the return manifolds 32 all extend along the transport direction. The four supply manifolds 31 are aligned at equal intervals in the scanning direction. The four return manifolds 32 are also aligned at equal intervals in the scanning direction. As shown in Figs. 3 and 4, the return manifolds 32 are located below the supply manifolds 31. The return manifolds 32 overlap with each of the supply manifolds 31 in the up-down direction. Black, yellow, cyan and magenta inks flow in the four supply manifolds 31 and the four return manifolds 32, respectively.

[0021] As shown in FIG. 4, an upstream end of the supply manifold 31 in the transport direction and an upstream end of the return manifold 32 in the transport direction are connected by a connecting flow path 33.

[0022] The supply manifold 31 communicates with the ink tank 6 via a supply port 31a provided at an end on the downstream side in the transport direction. The return manifold 32 communicates with the ink tank 6 via a return port 32a provided at an end on the downstream side in the transport direction. The supply port 31a and the return port 32a open to an upper surface 11x of the flow path unit 11.

[0023] As shown in Fig. 2, each of the individual flow paths 20 has a nozzle 21. A pair of supply manifold 31 and return manifold 32 aligned vertically is provided commonly to the individual flow paths 20 each having a plurality of nozzles 21 included in one nozzle row 21a (see Fig. 1). As shown in Fig. 3, each individual flow path 20 is located on the other side of the supply manifold 31 and return manifold 32 to which the individual flow path 20 is connected in the scanning direction.

[0024] Ink in the ink tank 6 is sent from the supply port 31a to the supply manifold 31 by a pump (not shown). The ink sent to the supply manifold 31 moves from the downstream side to the upstream side in the transport direction inside the supply manifold 31 and is supplied to each individual flow path 20 (see FIG. 3). The ink flowing out from each individual flow path 20 flows into the return manifold 32. Furthermore, the ink that reaches the upstream end of the supply manifold 31 in the transport direction flows into the return manifold 32 through the connecting flow path 33. The ink that has flowed into the return manifold 32 moves from the upstream side to the downstream side in the transport direction inside the return manifold 32 and is returned to the ink tank 6 via the return port 32a.

[0025] 3 and 4, the supply manifold 31 is composed of a recess that is open downward and formed in the plate 11c, and through holes that are formed in the plates 11d and 11e. The return manifold 32 is composed of a recess that is open downward and formed in the plate 11g, and through holes that are formed in the plates 11h and 11i.

[0026] A damper chamber 30 is provided between the supply manifold 31 and the return manifold 32 in the vertical direction. The damper chamber 30 is configured as a recess that is formed in the plate 11f and is open downward. The bottom of the recess in the plate 11f functions as a damper film 31d of the supply manifold 31. The bottom of the recess that constitutes the return manifold 32 in the plate 11g functions as a damper film 32d of the return manifold 32.

[0027] As shown in FIG. 3, each individual flow path 20 includes a nozzle 21, a pressure chamber 22, a connecting flow path 23 consisting of a first flow path 23a and a second flow path 23b, an inflow flow path 24, and an outflow flow path 25 (the "third flow path" of the present invention).

[0028] The nozzles 21 are constituted by through holes formed in the plate 11k, and open to a nozzle surface 11y which is the lower surface of the flow passage unit 11. That is, the nozzles 21 extend in the up-down direction.

[0029] The pressure chamber 22 is constituted by a through hole formed in the plate 11a, and opens to the upper surface 11x of the flow path unit 11. The pressure chamber 22 has an inflow flow path 24 connected to one end on the scanning direction side, and a connection flow path 23 connected to the other end on the scanning direction side.

[0030] The connection flow path 23 connects the nozzle 21 and the pressure chamber 22 to each other. The first flow path 23a of the connection flow path 23 is configured as a through hole formed in the plate 11j. The first flow path 23a overlaps with the nozzle 21 in a top view. That is, the nozzle 21 is connected to the first flow path 23a in the middle. The second flow path 23b of the connection flow path 23 is configured as a through hole formed in the plates 11b to 11i, and extends in the vertical direction. The second flow path 23b is separated from the nozzle 21 in the scanning direction and connects the pressure chamber 22 and the first flow path 23a. The second flow path 23b is located on the opposite side to the nozzle 21 across the first flow path 23a in the vertical direction. The connection flow path 23 will be described in detail later.

[0031] The inflow channel 24 connects the supply manifold 31 and the pressure chamber 22 to each other. The inflow channel 24 is composed of a recessed portion formed in the plate 11b that is open downwards, a through hole located at the other end of the recessed portion in the scanning direction, and a through hole formed in the plate 11c. More specifically, the inflow channel 24 is connected to the pressure chamber 22 by a through hole formed in the plate 11b. The inflow channel 24 is also connected to the supply manifold 31 by a through hole formed in the bottom of a recessed portion that constitutes the supply manifold 31 formed in the plate 11c. The inflow channel 24 has a smaller cross-sectional area in a plane perpendicular to the scanning direction (the ink flow direction) than the pressure chamber 22, and functions as a throttle.

[0032] The outflow flow path 25 connects the first flow path 23a of the connection flow path 23 and the return manifold 32 to each other. The outflow flow path 25 is connected to the first flow path 23a on the opposite side of the second flow path 23b across the nozzle 21 in the scanning direction. The outflow flow path 25 is composed of a recessed portion that is open downward and formed in the plate 11j, and a through hole located at one end of the recessed portion in the scanning direction. The through hole of the plate 11j that constitutes the outflow flow path 25 overlaps with the through hole that constitutes the return manifold 32 formed in the plate 11i in the vertical direction. The other end of the recessed portion of the plate 11j that constitutes the outflow flow path 25 in the scanning direction is connected to the through hole that constitutes the first flow path 23a of the connection flow path 23. The outflow flow path 25 has a cross-sectional area in a plane perpendicular to the ink flow direction smaller than that of the first flow path 23a of the connection flow path 23, and functions as a throttle.

[0033] Ink supplied from the supply manifold 31 to each individual flow path 20 flows into the pressure chamber 22 through the inflow flow path 24, moves approximately horizontally inside the pressure chamber 22, and flows into the connecting flow path 23. The ink that flows into the connecting flow path 23 moves downward in the second flow path 23b, and then flows into the first flow path 23a that extends in the horizontal plane. A portion of the ink that flows into the first flow path 23a is ejected from the nozzle 21, and the remainder flows into the return manifold 32 through the outflow flow path 25.

[0034] By circulating the ink between the ink tank 6 and the flow path unit 11 in this manner, it is possible to prevent air from being discharged and ink from thickening in the supply manifold 31 and the return manifold 32 formed in the flow path unit 11, and further in the individual flow paths 20. Furthermore, if the ink contains a sedimentation component (a component that may cause sedimentation, such as a pigment), the component is agitated to prevent sedimentation.

[0035] As shown in FIGS. 3 and 4, the piezoelectric actuator 12 includes, in order from the bottom, a vibration plate 12a, a common electrode 12b, a piezoelectric layer 12c, and a plurality of individual electrodes 12d.

[0036] The vibration plate 12a is disposed on the upper surface 11x of the flow path unit 11. A common electrode 12b, a piezoelectric layer 12c, and an individual electrode 12d, which are stacked in this order from below, are disposed in an area on the upper surface of the vibration plate 12a facing the multiple pressure chambers 22. The vibration plate 12a, the common electrode 12b, and the piezoelectric layer 12c are disposed across the multiple pressure chambers 22. The individual electrodes 12d are provided for each pressure chamber 22, and overlap with each pressure chamber 22 in a top view.

[0037] The common electrode 12b and the individual electrodes 12d are connected to a driver IC (not shown) via wiring members (not shown). The driver IC maintains the potential of the common electrode 12b at ground potential, while changing the potential of the individual electrodes 12d. As a result, the portion of the vibration plate 12a and the piezoelectric layer 12c sandwiched between the individual electrodes 12d and the pressure chambers 22 (actuators 12x) deforms so as to become convex toward the pressure chambers 22. This deformation reduces the volume of the pressure chambers 22, increasing the pressure of the ink in the pressure chambers 22, and ink is ejected from the nozzles 21 communicating with the pressure chambers 22. In other words, the piezoelectric actuator 12 has a plurality of actuators 12x corresponding to the respective pressure chambers 22.

[0038] <Connection flow path 23> Next, the connection flow path 23 will be described in more detail with further reference to Figures 5 and 6. Note that Figure 6 is a plan view of the plate 11j in which the first flow path 23a of the connection flow path 23 is formed, and the nozzle 21 and the second flow path 23b of the connection flow path 23 are indicated by dashed lines.

[0039] 5, one end of the first flow path 23a of the connection flow path 23 in the scanning direction is connected to the outflow flow path 25. The first flow path 23a is curved so as to bulge toward the downstream side in the transport direction within a horizontal plane.

[0040] Note that "bulging downstream in the transport direction" means that, with respect to the scanning direction of the first flow path 23a, an end portion (an end portion on the other side) opposite to the side to which the outflow flow path 25 is connected is taken as a reference, there is a portion that protrudes downstream in the transport direction from the end portion on the other side that serves as the reference. Also, the direction in which the first flow path 23a protrudes from the end portion on the other side is referred to as the "curving direction of the first flow path." That is, in this embodiment, the curving direction of the first flow path is the downstream side in the transport direction.

[0041] Here, two different points on the periphery of the first flow path 23a in the connection flow path 23 in a plan view are defined as points a1 and a2, and the two points are defined as the longest line segment connecting the two points. In addition, the direction parallel to the imaginary straight line La1 passing through the points a1 and a2 in a plan view is defined as the longitudinal direction, and the direction perpendicular to the longitudinal direction is defined as the transverse direction. In this embodiment, the longitudinal direction is parallel to the scanning direction, and the transverse direction is parallel to the transport direction. The periphery of the first flow path 23a can be divided into a first portion 23a1 and a second portion 23a2, both of which connect the two points a1 and a2. As shown in FIG. 5, the first portion 23a1 is located on one side of the imaginary straight line La1 in the transverse direction, and the second portion 23a2 is located on the other side of the imaginary straight line La1 in the transverse direction.

[0042] The first portion 23a1 of the periphery of the first flow path 23a has a convex shape that protrudes to one side in the short side direction as a whole. The apex of the convex shape of the first portion 23a1 is defined as point a3. The second portion 23a2 of the periphery of the first flow path 23a has a shape in which a convex portion protruding to one side in the short side direction is located between two convex portions protruding to the other side in the short side direction. The apexes of the two convex portions protruding to the other side in the short side direction of the second portion 23a2 are defined as points a4 and a5, respectively, and the apex of the convex portion protruding to one side in the short side direction of the second portion 23a2 is defined as point a6. At this time, the position of the imaginary straight line La2 passing through points a3 and a6 is defined as the bending position of the first flow path 23a. The first flow path 23a has a shape symmetrical with respect to the imaginary straight line La2.

[0043] A connection point where the wall surface 25a on the upstream side in the transport direction of the wall surface defining the outflow flow path 25 is connected to the wall surface defining the first flow path 23a is defined as point a7. A straight line extending along the scanning direction and passing through point a7 is defined as imaginary line La3. In this case, imaginary line La3 does not intersect with the wall surface defining the first flow path 23a at positions other than the positions of both ends of the first flow path 23a on imaginary line La3 (positions indicated by points a7 and a8 in FIG. 5).

[0044] In top view, a tangent to points a1 and a3 at the center position in the longitudinal direction of the first portion 23a1 of the periphery of the first flow path 23a is defined as a virtual line La4. In top view, a tangent to points a2 and a3 at the center position in the longitudinal direction of the first portion 23a1 of the periphery of the first flow path 23a is defined as a virtual line La5. Note that the virtual lines La4 and La5 are both half lines whose end points are their intersections. At this time, the angle between the virtual lines La4 and La5 is the first bending angle θa1 of the first flow path 23a. The bending angle θa1 is 90° or more.

[0045] In top view, a tangent to points a4 and a6 at the center position in the longitudinal direction of the second portion 23a2 of the periphery of the first flow path 23a is defined as a virtual line La6. In top view, a tangent to points a5 and a6 at the center position in the longitudinal direction of the second portion 23a2 of the periphery of the first flow path 23a is defined as a virtual line La7. Note that the virtual lines La6 and La7 are both half lines whose end points are their intersections. At this time, the angle between the virtual lines La6 and La7 is the second bending angle θa2 of the first flow path 23a. The bending angle θa2 is 90° or more.

[0046] 5, the nozzle 21 is connected to the center of the first flow path 23a in the transport direction. The nozzle 21 is located at a position that does not overlap with the second flow path 23b of the connection flow path 23 in a top view. The nozzle 21 is located closer to the outflow flow path 25 than the bending position (position of the virtual straight line La2) of the first flow path 23a in a top view. The second flow path 23b of the connection flow path 23 is located on the opposite side to the nozzle 21 across the bending position (position of the virtual straight line La2) of the first flow path 23a in a top view.

[0047] As described above, because the first flow path 23a is curved so as to bulge toward the downstream side in the transport direction, the flow direction of the ink flowing from the second flow path 23b into the first flow path 23a toward the outflow flow path 25 is curved so as to bulge toward the downstream side in the transport direction, as shown by the dashed arrow in Fig. 5. As a result, the flow speed of the ink in the first flow path 23a becomes faster toward the downstream side in the transport direction.

[0048] As shown in Fig. 6, a plurality of first flow paths 23a of the connection flow paths 23 are formed in the plate 11j. The plurality of first flow paths 23a to which the plurality of nozzles 21 included in one nozzle row 21a are respectively connected are aligned in a line along the transport direction. The bending direction of the plurality of first flow paths 23a aligned in a line is the same direction (downstream side in the transport direction). In addition, the bending direction of the first flow paths 23a to which each nozzle 21 included in the nozzle row 21a is connected is the same direction (downstream side in the transport direction) between the nozzle rows 21a.

[0049] <Features of the embodiment> As described above, the inkjet head 1 of the embodiment described above includes a plurality of individual flow paths 20 to which ink is supplied from the supply manifold 31 and which returns a portion of the supplied ink to the return manifold 32. Each of the plurality of individual flow paths 20 includes a pressure chamber 22, a nozzle 21 for ejecting ink, a connection flow path 23 connecting the pressure chamber 22 and the nozzle 21, and an outflow flow path 25 connected to the return manifold 32. The connection flow path 23 includes a first flow path 23a to which the nozzle 21 is connected, and a second flow path 23b that is separated from the nozzle 21 in the scanning direction and connects the pressure chamber 22 and the first flow path 23a. The outflow flow path 25 is connected to the first flow path 23a on the opposite side to the second flow path 23b across the nozzle 21 in the scanning direction. The first flow path 23a is bent so as to bulge toward one side (downstream side) in the transport direction perpendicular to the scanning direction, and the flow direction of the ink flowing in the first flow path 23a is bent so as to bulge toward one side (downstream side) in the transport direction.

[0050] According to the above-mentioned configuration, the flow direction of the ink in the first flow path 23a is bent so as to bulge to one side in the transport direction, so that the flow speed of the ink at the end of the first flow path 23a on one side in the transport direction can be increased compared to when the flow direction of the liquid in the first flow path 23a is linear. Therefore, the thickened ink at the end of the nozzle 21 connected to the first flow path 23a can be reliably removed.

[0051] In the inkjet head 1 of the above embodiment, the first flow path 23a is curved in the horizontal plane, which makes it possible to smooth the flow of ink in the first flow path 23a and to make it difficult for turbulence to occur.

[0052] Furthermore, in the inkjet head 1 of the above-described embodiment, the nozzle 21 is connected to the center of the first flow path 23a in the transport direction, so that thickened ink at the end of the nozzle 21 can be removed more reliably.

[0053] Additionally, in the inkjet head 1 of the above embodiment, both the nozzle 21 and the second flow path 23b extend in the vertical direction. The second flow path 23b is located on the opposite side of the first flow path 23a from the nozzle 21 in the vertical direction. The nozzle 21 is located at a position that does not overlap with the second flow path 23b when viewed from the vertical direction. Therefore, it is possible to prevent air that has entered the first flow path 23a from the nozzle 21 from being pushed into the nozzle 21 by the flow of ink from the second flow path 23b to the first flow path 23a (flow along the vertical direction).

[0054] Furthermore, in the inkjet head 1 of the above embodiment, a plurality of nozzle rows 21a each composed of a plurality of nozzles 21 aligned along the transport direction are provided in the scanning direction, and the bending direction of the first flow path 23a to which each nozzle 21 included in the nozzle row 21a is connected is the same between the nozzle rows 21a. Therefore, the flow direction of the ink flowing in the first flow path 23a connected to each nozzle 21 included in the nozzle row 21a is the same between the nozzle rows 21a, so that the direction of the flight bending of the ink ejected from each nozzle 21 included in the nozzle row 21a can be aligned between the nozzle rows 21a.

[0055] In the inkjet head 1 of the above embodiment, the cross-sectional area of ​​the outflow channel 25 in a plane perpendicular to the ink flow direction is smaller than that of the first channel 23a. Therefore, the pressure for ejecting ink by driving the piezoelectric actuator 12 is less likely to escape to the outflow channel 25, and ink can be ejected reliably from the nozzle 21.

[0056] Additionally, in the inkjet head 1 of the embodiment described above, the outflow flow path 25 extends along the scanning direction. A virtual line La3 that extends along the scanning direction and passes through a connection point (point a7) where a wall surface 25a on the upstream side in the transport direction of the wall surface defining the outflow flow path 25 is connected to a wall surface defining the first flow path 23a does not intersect with the wall surface defining the first flow path 23a at positions on the virtual line La3 other than the positions of both ends of the first flow path 23a (points a7 and a8).

[0057] Here, when point a6 (see FIG. 5) on the periphery of the second portion 23a2 in the first flow path 23a is located downstream of the imaginary line La3 in the transport direction, the imaginary line La3 intersects with the wall surface defining the first flow path 23a at points other than points a7 and a8. In this case, a stagnation point occurs in a portion of the first flow path 23a on one side of point a6 in the scanning direction and upstream of the imaginary line La3 in the transport direction. With the above-mentioned configuration, it is possible to make it difficult for a stagnation point to occur in the first flow path 23a, and to make it easier to discharge air from the first flow path 23a.

[0058] In the inkjet head 1 of the above embodiment, the bending angles θa1 and θa2 of the first flow paths 23a are both 90° or more. If the bending angles of the first flow paths 23a are acute angles, it is difficult to fabricate the first flow paths 23a, and the shape of the first flow paths 23a varies among the multiple individual flow paths 20. With the above configuration, it is possible to make it difficult for the shape of the first flow paths 23a to vary among the multiple individual flow paths 20.

[0059] Although the embodiments of the present invention have been described above based on the drawings, the specific configuration should not be considered to be limited to these embodiments. The scope of the present invention is indicated by the claims rather than the description of the above embodiments, and further includes all modifications within the meaning and scope of the claims.

[0060] In the above embodiment, the first flow path 23a of the connection flow path 23 has a longitudinal direction parallel to the scanning direction and a lateral direction parallel to the transport direction, but the present invention is not limited to this. Fig. 7 shows the first flow path 123a of the connection flow path 123 according to a first modified example of the above embodiment. As shown in Fig. 7, the first flow path 123a according to this modified example has the same shape as the first flow path 23a of the above embodiment, but the longitudinal direction is inclined with respect to the scanning direction and the lateral direction is inclined with respect to the transport direction.

[0061] The first flow path 123a is curved so as to bulge toward the downstream side in the transport direction in a horizontal plane. That is, the first flow path 123a has a portion that bulges out toward the downstream side in the transport direction from the end (the other end) of the first flow path 123a opposite to the side to which the outflow flow path 25 is connected in the scanning direction, which is the reference end. As shown by the dashed-dotted arrow in FIG. 7, the flow direction of the ink that flows from the second flow path 123b into the first flow path 123a and toward the outflow flow path 25 is curved so as to bulge toward the downstream side in the transport direction.

[0062] Furthermore, in the above embodiment, the first flow path 23a is curved within a horizontal plane, but the present invention is not limited to this.

[0063] Here, Fig. 8 shows the first flow path 223a of the connection flow path 223 according to the second modified example of the above-mentioned embodiment. As shown in Fig. 8, the first flow path 223a is bent within a horizontal plane.

[0064] The first flow path 223a is bent so as to bulge toward the downstream side in the transport direction in a horizontal plane. That is, the first flow path 223a has a portion that bulges out toward the downstream side in the transport direction from the end (the other end) of the first flow path 223a opposite to the side to which the outflow flow path 25 is connected in the scanning direction, which is the reference end. As shown by the dashed-dotted arrow in FIG. 8, the flow direction of the ink that flows from the second flow path 223b into the first flow path 223a and toward the outflow flow path 25 is bent so as to bulge toward the downstream side in the transport direction.

[0065] Here, two different points on the periphery of the first flow path 223a in the connection flow path 223 in a plan view are defined as points b1 and b2, and the line segment connecting the two points is the longest. In addition, the direction parallel to the imaginary straight line Lb1 passing through the points b1 and b2 in a plan view is defined as the longitudinal direction, and the direction perpendicular to the longitudinal direction is defined as the lateral direction.

[0066] In this modification, the longitudinal direction is inclined with respect to the scanning direction, and the lateral direction is inclined with respect to the transport direction. The periphery of the first flow path 223a can be divided into a first portion 223a1 and a second portion 223a2, each of which connects two points b1 and b2. As shown in FIG. 8, the first portion 223a1 is located on one side of a virtual straight line Lb1 in the lateral direction, and the second portion 223a2 is located on the other side of the virtual straight line Lb1 in the lateral direction.

[0067] The first portion 23a1 of the periphery of the first flow path 223a is bent at three points, namely, points b3, b4, and b5. The second portion 223a2 of the periphery of the first flow path 223a is bent at three points, namely, points b6, b7, and b8. The bending angles θb1, θb2, θb3, θb4, θb5, and θb6 at the six bending positions, namely, points b3 to b8, are all 90° or more. The position of the imaginary straight line Lb2 passing through point b4, which is the middle bending position among the three bending positions of the first portion 23a1, and point b7, which is the middle bending position among the three bending positions of the second portion 223a2, is defined as the bending position of the first flow path 323a.

[0068] The nozzle 21 is located closer to the outflow flow path 25 than the bending position (position of the virtual straight line Lb2) of the first flow path 223a in top view. The second flow path 223b of the connection flow path 223 is located on the opposite side to the nozzle 21 across the bending position (position of the virtual straight line Lb2) of the first flow path 223a in top view. The nozzle 21 is connected to the center of the first flow path 223a in the transport direction. The nozzle 21 is located at a position that does not overlap with the second flow path 223b of the connection flow path 223 in top view.

[0069] A connection point where the wall surface defining the first flow path 223a and the wall surface defining the outflow flow path 25 are connected to the wall surface 25a on the upstream side in the transport direction is defined as point b9. A straight line extending along the scanning direction and passing through point b9 is defined as an imaginary line Lb3. At this time, the imaginary line Lb3 does not intersect with the wall surface defining the first flow path 223a at positions other than the positions of both ends of the first flow path 223a on the imaginary line Lb3 (positions indicated by points b9 and b10 in FIG. 8).

[0070] Furthermore, a first flow path 323a of a connection flow path 323 according to a third modified example of the above-described embodiment is shown in Fig. 9. As shown in Fig. 9, the first flow path 323a is bent within a horizontal plane.

[0071] The first flow path 323a is bent so as to bulge toward the downstream side in the transport direction within a horizontal plane. That is, the first flow path 323a has a portion that bulges out toward the downstream side in the transport direction from the end (the other end) of the first flow path 323a opposite to the side to which the outflow flow path 25 is connected in the scanning direction, which is the reference end. As shown by the dashed-dotted arrow in FIG. 9, the flow direction of the ink that flows from the second flow path 323b into the first flow path 323a and toward the outflow flow path 25 is bent so as to bulge toward the downstream side in the transport direction.

[0072] Here, two different points on the periphery of the first flow path 323a in the connection flow path 323 in a plan view are defined as points c1 and c2, and the two points are the longest line segment connecting the two points. In addition, the direction parallel to the virtual line Lc1 passing through the points c1 and c2 in a plan view is defined as the longitudinal direction, and the direction perpendicular to the longitudinal direction is defined as the transverse direction. In this modification, the longitudinal direction is parallel to the scanning direction, and the transverse direction is parallel to the transport direction. The periphery of the first flow path 323a can be divided into a first portion 323a1 and a second portion 323a2, both of which connect the two points c1 and c2. That is, the first portion 323a1 is located downstream of the second portion 223a2 in the transport direction.

[0073] A first portion 323a1 of the periphery of the first flow path 323a is bent at point c3. A second portion 323a2 of the periphery of the first flow path 323a is bent at three points, points c4, c5, and c6. The bending angles θc1, θc2, θc3, and θc4 at the four bending positions, points c3 to c6, are all 90° or more. The position of a virtual straight line Lc2 passing through point c3, which is the bending position of the first portion 323a1, and point c5, which is the middle bending position of the three bending positions of the second portion 323a2, is defined as the bending position of the first flow path 323a.

[0074] The nozzle 21 is located closer to the outflow flow path 25 than the bending position (position of the virtual straight line Lc2) of the first flow path 323a in top view. The second flow path 323b of the connection flow path 323 is located on the opposite side to the nozzle 21 across the bending position (position of the virtual straight line Lc2) of the first flow path 323a in top view. The nozzle 21 is connected to the center of the first flow path 323a in the transport direction. The nozzle 21 is located at a position that does not overlap with the second flow path 323b of the connection flow path 323 in top view.

[0075] A connection point where the wall surface defining the first flow path 323a and the wall surface defining the outflow flow path 25 are connected to the wall surface 25a on the upstream side in the transport direction is defined as point c7. A straight line extending along the scanning direction and passing through point c7 is defined as a virtual line Lc3. In this case, the virtual line Lc3 does not intersect with the wall surface defining the first flow path 323a at positions other than the positions of both ends of the first flow path 323a on the virtual line Lc3 (positions indicated by points c7 and c8 in FIG. 9).

[0076] In the above embodiment, the nozzle 21 is connected to the center of the first flow path 323a in the transport direction, but the present invention is not limited to this. That is, the nozzle 21 may be connected to the downstream side of the first flow path 323a in the transport direction, or may be connected to the upstream side of the first flow path 323a in the transport direction.

[0077] Furthermore, in the above embodiment, the nozzle 21 and the second flow path 23b both extend in the vertical direction and are parallel to each other, but this is not limiting. The nozzle 21 and the second flow path 23b may extend in different directions.

[0078] In the above embodiment, the bending direction of the first flow paths 23a to which the nozzles 21 included in the nozzle rows 21a are connected is the same for the nozzle rows 21a, but this is not limited thereto. The bending direction of the first flow paths 23a may be different for the nozzle rows 21a.

[0079] In addition, in the above embodiment, the virtual straight line La3, which is a virtual straight line extending along the scanning direction and passes through a connection point (point a7) where the wall surface 25a on the upstream side in the transport direction of the wall surface defining the outflow flow path 25 is connected to the wall surface defining the first flow path 23a, does not intersect with the wall surface defining the first flow path 23a at positions other than the positions of both ends of the first flow path 23a (points a7 and a8) on the virtual straight line La3, but is not limited to this. The virtual straight line La3 may intersect with the wall surface defining the first flow path 23a at positions other than the positions of both ends of the first flow path 23a on the virtual straight line La3.

[0080] Furthermore, in the above embodiment, the bending angle of the first flow passage 23a is 90° or more. However, the bending angle of the first flow passage 23a may be less than 90°.

[0081] Furthermore, in the above embodiment, the nozzle 21 is located closer to the outlet flow path 25 than the bending position of the first flow path 23a in top view, and the second flow path 23b is located on the opposite side to the nozzle 21 across the bending position of the first flow path 23a in top view, but this is not limiting. The nozzle 21 and the second flow path 23b may be located on the same side of the bending position of the first flow path 23a.

[0082] In addition, in the above embodiment, the outflow channel 25 is connected to one end of the first channel 23a in the connection channel 23 in the scanning direction, but the present invention is not limited to this.

[0083] Here, Fig. 10 shows a plate 411j in which a first flow path 423a of a connection flow path 423 according to a fourth modified example of the above-described embodiment is formed. In Fig. 10, the nozzles 21 and the second flow paths 423b of the connection flow paths 423 are indicated by dashed lines. As shown in Fig. 10, in this modified example, the location at which the outflow flow path 25 is connected to the first flow paths 423a to which each nozzle 21 included in the nozzle row 21a is connected differs between the nozzle rows 21a.

[0084] That is, the first flow paths 423a to which the nozzles 21 included in the nozzle row 21a located at the upper side in Fig. 10 are connected have an outlet flow path 25 connected to an end portion on the other side in the scanning direction. On the other hand, the first flow paths 423a to which the nozzles 21 included in the nozzle row 21a located at the lower side in Fig. 10 are connected have an outlet flow path 25 connected to an end portion on one side in the scanning direction. In this modified example, the bending direction of the first flow paths 423a to which the nozzles 21 included in the nozzle row 21a are connected is the same between the nozzle rows 21a.

[0085] The actuator 12x is not limited to a piezoelectric type using a piezoelectric element, and may be of another type (for example, a thermal type using a heating element, an electrostatic type using electrostatic force, etc.).

[0086] The recording format of the printer 100 is not limited to a serial type, but may be a line type in which ink is ejected from nozzles of a head that is long in the width direction of the recording paper P and is fixed in position.

[0087] The liquid ejected from the nozzle 21 is not limited to ink, and may be any liquid (for example, a treatment liquid that aggregates or precipitates the components in the ink). In addition, the object to be ejected is not limited to the recording paper P, and may be, for example, a cloth, a substrate, etc.

[0088] The present invention is not limited to printers, but can also be applied to facsimiles, copy machines, multifunction machines, etc. The present invention can also be applied to liquid ejection devices used for purposes other than image recording (for example, liquid ejection devices that eject conductive liquid onto a substrate to form a conductive pattern). [Explanation of symbols]

[0089] 1 Inkjet head 20 Individual Channels 21 Nozzle 21a Nozzle row 22 Pressure Chamber 23a First flow path 23b Second flow path 25 Outlet channel (third channel) 31 Supply manifold (first common liquid chamber) 32 Return manifold (second common liquid chamber)

Claims

1. A plurality of individual flow paths; a first common liquid chamber that is provided in common to the plurality of individual flow paths and that supplies liquid to the plurality of individual flow paths; a second common liquid chamber that is provided in common to the plurality of individual flow paths and into which liquid from the plurality of individual flow paths flows, Each of the plurality of individual flow paths is A pressure chamber; A nozzle for discharging a liquid; a first flow path to which the nozzle is connected; a second flow passage that is separated from the nozzle in a first direction along a nozzle face in which the nozzle opens, and that connects the pressure chamber and the first flow passage; a third flow path connected to the first flow path on an opposite side to the second flow path across the nozzle in the first direction, the first flow path is curved so as to bulge toward one side of a second direction that is along the nozzle surface and perpendicular to the first direction, and a flow direction of liquid flowing in the first flow path is curved so as to bulge toward one side of the second direction, a plurality of nozzle rows each including a plurality of the nozzles aligned along the second direction are provided in the first direction; A liquid ejection head, characterized in that the bending direction of the first flow path to which each of the nozzles included in the nozzle row is connected is the same between the nozzle rows.

2. A plurality of individual flow paths; a first common liquid chamber that is provided in common to the plurality of individual flow paths and that supplies liquid to the plurality of individual flow paths; a second common liquid chamber that is provided in common to the plurality of individual flow paths and into which liquid from the plurality of individual flow paths flows, Each of the plurality of individual flow paths is A pressure chamber; A nozzle for discharging a liquid; a first flow path to which the nozzle is connected; a second flow passage that is separated from the nozzle in a first direction along a nozzle face in which the nozzle opens, and that connects the pressure chamber and the first flow passage; a third flow path connected to the first flow path on an opposite side to the second flow path across the nozzle in the first direction, the first flow path is curved so as to bulge toward one side of a second direction that is along the nozzle surface and perpendicular to the first direction, and a flow direction of liquid flowing in the first flow path is curved so as to bulge toward one side of the second direction, The liquid ejection head according to claim 1, wherein the third flow path has a smaller cross-sectional area in a plane perpendicular to a flow direction of the liquid than the first flow path.

3. A plurality of individual flow paths; a first common liquid chamber that is provided in common to the plurality of individual flow paths and that supplies liquid to the plurality of individual flow paths; a second common liquid chamber that is provided in common to the plurality of individual flow paths and into which liquid from the plurality of individual flow paths flows, Each of the plurality of individual flow paths is A pressure chamber; A nozzle for discharging a liquid; a first flow path to which the nozzle is connected; a second flow passage that is separated from the nozzle in a first direction along a nozzle face in which the nozzle opens, and that connects the pressure chamber and the first flow passage; a third flow path connected to the first flow path on an opposite side to the second flow path across the nozzle in the first direction, the first flow path is curved so as to bulge toward one side of a second direction that is along the nozzle surface and perpendicular to the first direction, and a flow direction of liquid flowing in the first flow path is curved so as to bulge toward one side of the second direction, The third flow path extends along the first direction, A liquid ejection head characterized in that a virtual straight line extending along the first direction, passing through a connection point where a wall surface defining the first flow path is connected to a wall surface defining the third flow path on the other side of the second direction, does not intersect with the wall surface defining the first flow path at a position on the virtual line other than the positions of both ends of the first flow path.

4. A plurality of individual flow paths; a first common liquid chamber that is provided in common to the plurality of individual flow paths and that supplies liquid to the plurality of individual flow paths; a second common liquid chamber that is provided in common to the plurality of individual flow paths and into which liquid from the plurality of individual flow paths flows, Each of the plurality of individual flow paths is A pressure chamber; A nozzle for discharging a liquid; a first flow path to which the nozzle is connected; a second flow passage that is separated from the nozzle in a first direction along a nozzle face in which the nozzle opens, and that connects the pressure chamber and the first flow passage; a third flow path connected to the first flow path on an opposite side to the second flow path across the nozzle in the first direction, the first flow path is curved so as to bulge toward one side of a second direction that is along the nozzle surface and perpendicular to the first direction, and a flow direction of liquid flowing in the first flow path is curved so as to bulge toward one side of the second direction, the nozzle is located on the third flow path side of a bending position of the first flow path when viewed from a third direction perpendicular to both the first direction and the second direction, The liquid ejection head is characterized in that the second flow path is located on the opposite side to the nozzle across a bent position of the first flow path when viewed from the third direction.

5. 5. The liquid ejection head according to claim 1, wherein the first flow path is curved within a plane parallel to the nozzle surface.

6. 5. The liquid ejection head according to claim 1, wherein the first flow path is bent within a plane parallel to the nozzle surface.

7. A plurality of individual flow paths; a first common liquid chamber that is provided in common to the plurality of individual flow paths and that supplies liquid to the plurality of individual flow paths; a second common liquid chamber that is provided in common to the plurality of individual flow paths and into which liquid from the plurality of individual flow paths flows, Each of the plurality of individual flow paths is A pressure chamber; A nozzle for discharging a liquid; a first flow path to which the nozzle is connected; a second flow passage that is separated from the nozzle in a first direction along a nozzle face in which the nozzle opens, and that connects the pressure chamber and the first flow passage; a third flow path connected to the first flow path on an opposite side to the second flow path across the nozzle in the first direction, the first flow path is curved so as to bulge toward one side of a second direction that is along the nozzle surface and perpendicular to the first direction, and a flow direction of liquid flowing in the first flow path is curved so as to bulge toward one side of the second direction, the first flow path is curved within a plane parallel to the nozzle surface, When viewed from a third direction perpendicular to both the first direction and the second direction, Two different points on a periphery of the first flow path, the two points being the longest line segment connecting the two points, are defined as a first point and a second point, A direction parallel to a virtual line passing through the first point and the second point is defined as a longitudinal direction, and a direction perpendicular to the longitudinal direction is defined as a lateral direction, a periphery of the first flow path is divided into a first portion which is a portion connecting the first point and the second point and has a convex shape protruding to one side in the short side direction as a whole, and a second portion which has a shape in which a convex portion protruding to the one side in the short side direction is located between two convex portions protruding to the other side in the short side direction, The apex of the convex shape of the first portion is defined as a third point; When the vertices of the two convex portions protruding to the other side in the short side direction of the second portion are defined as a fourth point and a fifth point, respectively, and the vertex of the convex portion protruding to the one side in the short side direction of the second portion is defined as a sixth point, a first bending angle, which is an angle between a tangent at a central position in the longitudinal direction between the first point and the third point in the first portion and a tangent at a central position in the longitudinal direction between the second point and the third point in the first portion, is 90° or more; A liquid ejection head characterized in that a second bending angle, which is the angle between a tangent at a central position in the longitudinal direction between the fourth point and the sixth point in the second portion and a tangent at a central position in the longitudinal direction between the fifth point and the sixth point in the second portion, is 90° or more.

8. A plurality of individual flow paths; a first common liquid chamber that is provided in common to the plurality of individual flow paths and that supplies liquid to the plurality of individual flow paths; a second common liquid chamber that is provided in common to the plurality of individual flow paths and into which liquid from the plurality of individual flow paths flows, Each of the plurality of individual flow paths is A pressure chamber; A nozzle for discharging a liquid; a first flow path to which the nozzle is connected; a second flow passage that is separated from the nozzle in a first direction along a nozzle face in which the nozzle opens, and that connects the pressure chamber and the first flow passage; a third flow path connected to the first flow path on an opposite side to the second flow path across the nozzle in the first direction, the first flow path is curved so as to bulge toward one side of a second direction that is along the nozzle surface and perpendicular to the first direction, and a flow direction of liquid flowing in the first flow path is curved so as to bulge toward one side of the second direction, the first flow path is bent in a plane parallel to the nozzle surface, When viewed from a third direction perpendicular to both the first direction and the second direction, Two different points on a periphery of the first flow path, the two points being the longest line segment connecting the two points, are defined as a first point and a second point, When a periphery of the first flow path is divided into a first portion and a second portion, both of which are portions connecting the first point and the second point, A liquid ejection head characterized in that the first portion and the second portion are both polygonal lines connected by a plurality of line segments and having one or more bend positions, and the bend angle between the two line segments connected at the bend position is 90° or greater.

9. 9. The liquid ejection head according to claim 1, wherein the nozzle is connected to a center of the first flow path in the second direction.

10. the second flow path has an extension direction parallel to an extension direction of the nozzle, and is located on an opposite side to the nozzle across the first flow path in a third direction perpendicular to both the first direction and the second direction, 10. The liquid ejection head according to claim 1, wherein the nozzle is positioned so as not to overlap with the second flow path when viewed from the extending direction of the nozzle.

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