Liquid ejection head

Abstract

To provide a liquid discharge head, which is configured so that air flowing into a flow passage can be smoothly ejected and also crosstalk is prevented from occurring.SOLUTION: A plurality of nozzles 10 formed in a nozzle plate 22 is connected to a plurality of pressure chambers 31 formed in a pressure chamber plate 24 through a plurality of descenders 32 formed in a flow passage substrate 21 arranged between the nozzle plate 22 and the pressure chamber plate 24. The plurality of descenders 32 and a second common flow passage 37 are arranged with an interval in a conveying direction. Each descender 32 is connected to the second common flow passage 37 through second diaphragms 34. The second diaphragms 34 have: first flow path portions 34a formed of upper portions of the nozzle plate 22 and connected to the descenders 32; and second flow passage portions 34b, formed on the flow passage substrate 21 and connecting the first flow passage portions 34a to the second common flow passage 37, which second flow passage portions are shorter in length in a vertical direction than the second common flow passage 37.SELECTED DRAWING: Figure 3

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 a liquid ejection head that ejects liquid from nozzles. In the liquid ejection head described in Patent Document 1, a plurality of pressure chambers that communicate with a supply flow path are each connected to a nozzle via a communication passage. In addition, each of the plurality of communication passages is connected to a recovery liquid chamber via a recovery passage. In addition, the recovery passage is formed in a nozzle plate in which the nozzles are formed. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2019-166705 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the liquid jet head of Patent Document 1, air that flows into the pressure chamber together with the liquid can be discharged to the recovered liquid chamber via a recovery path connected to a portion of the communication path near the nozzle. However, if the recovery path is long, the flow resistance of the recovery path increases, and the liquid does not flow smoothly from the communication path to the recovered liquid chamber via the recovery path. In this case, the air cannot be discharged smoothly.

[0005] On the other hand, if the length of the recovery path is shortened in order to reduce the flow resistance of the recovery path, the partition separating the communicating path and the recovered liquid chamber becomes thinner, and when pressure is applied to the liquid in a pressure chamber to eject the liquid from the nozzle, there is a risk that the pressure change in the liquid in the communicating path corresponding to that pressure chamber will be transmitted to the liquid in other communicating paths due to deformation of this partition, resulting in so-called crosstalk.

[0006] Furthermore, in the liquid jet head of Patent Document 1, the recovery path is formed in a thin nozzle plate, and multiple recovery paths are arranged in a row, so it is difficult to reduce the flow resistance of the recovery path by increasing either the length of the recovery path in the thickness direction of the nozzle plate or the length of the recovery path in the direction in which the multiple recovery paths are arranged, thereby increasing the cross-sectional area of ​​the cross section perpendicular to the longitudinal direction of the recovery path.

[0007] An object of the present invention is to provide a liquid ejection head that is less likely to cause crosstalk while being able to smoothly exhaust air that has flowed into a flow path. [Means for solving the problem]

[0008] A liquid ejection head according to the present invention includes a plurality of nozzles formed in a nozzle plate and arranged in a first direction, a plurality of pressure chambers formed in a pressure chamber plate arranged on one side of the nozzle plate in a second direction perpendicular to the first direction, the plurality of pressure chambers being individually provided for the plurality of nozzles and arranged in the first direction, a plurality of descenders formed in a flow path substrate arranged between the nozzle plate and the pressure chamber plate in the second direction, the descenders being arranged in the first direction, and extending in the second direction to connect the corresponding nozzles and the pressure chambers, a first common flow path connected to the plurality of pressure chambers, a second common flow path formed in the flow path substrate, overlapping with the plurality of descenders in a third direction perpendicular to both the first direction and the second direction, and separated from the plurality of descenders by a partition wall formed by the flow path substrate, and a connection flow path connecting the plurality of descenders and the second common flow path, the connection flow path being formed in the nozzle plate. a plurality of descenders each provided for each of the plurality of descenders and connected to the corresponding descenders; a first flow path portion; and the second common flow path a second flow path portion connected to the second common flow path and having a length in the second direction shorter than that of the second common flow path; the second direction is a vertical direction, the second flow path portion is connected to an end face of the second common flow path in the third direction, a ceiling surface which is an inner wall surface on an upper side of the second flow path portion has an inclined surface inclined with respect to a longitudinal direction of the second flow path portion so as to face upward as it approaches the second common flow path in the longitudinal direction of the second flow path portion, the ceiling surface has a connecting surface connected to an end of the inclined surface on the second common flow path side in the third direction, and an angle formed between the inclined surface and the connecting surface is an obtuse angle. . Furthermore, the liquid ejection head of the present invention includes a plurality of nozzles formed in a nozzle plate and arranged in a first direction, a plurality of pressure chambers formed in a pressure chamber plate arranged on one side of the nozzle plate in a second direction perpendicular to the first direction, the plurality of pressure chambers being provided individually for the plurality of nozzles and arranged in the first direction, a plurality of descenders formed in a flow path substrate arranged between the nozzle plate and the pressure chamber plate in the second direction, the descenders being arranged in the first direction, extending in the second direction and connecting the corresponding nozzles and the pressure chambers, a first common flow path connected to the plurality of pressure chambers, and a plurality of descenders formed in the flow path substrate and extending perpendicular to both the first direction and the second direction. and a second common flow path that overlaps with the plurality of descenders in a third direction and is separated from the plurality of descenders by a partition wall formed by the flow path substrate, and a connection flow path that connects the plurality of descenders and the second common flow path, wherein the connection flow path has a plurality of first flow path portions that are formed in the nozzle plate and provided individually for the plurality of descenders and connected to the corresponding descenders, and a second flow path portion that is formed in the flow path substrate and extends in the first direction across two or more adjacent first flow path portions among the plurality of first flow path portions, is connected to the two or more first flow path portions and the second common flow path, and has a length in the second direction shorter than that of the second common flow path. [Brief description of the drawings]

[0009] [Figure 1] 1 is a schematic configuration diagram of a printer 1 according to an embodiment of the present invention. [Diagram 2] FIG. [Diagram 3] 3A is a cross-sectional view taken along line IIIA-IIIA in FIG. 2, and FIG. 3B is an enlarged view of part IIIB in FIG. [Figure 4] FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. [Diagram 5] FIG. 5 is a diagram corresponding to FIG. 4 of the first modified example. [Figure 6] FIG. 5 is a diagram of the second modified example corresponding to FIG. [Figure 7] 3A is a view corresponding to FIG. 3A of Modification 3, and FIG. 3B is an enlarged view of portion VIIB of FIG. [Figure 8] FIG. 8 is a cross-sectional view taken along line VIII-VIII in FIG. [Figure 9] FIG. 11 is a diagram of modified example 4 corresponding to FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Preferred embodiments of the present invention will now be described.

[0011] <Overall configuration of Printer 1> 1, the printer 1 according to this embodiment includes four head units 2, a platen 3, and transport roller pairs 4 and 5. The four head units 2 are arranged side by side in a horizontal transport direction (the "third direction" of the present invention) in which the recording paper P is transported by the transport roller pairs 4 and 5, as described below. Each head unit 2 includes eight heads 11 (the "liquid ejection heads" of the present invention) and a head holding member 12.

[0012] The head 11 ejects ink from a plurality of nozzles 10 formed on its underside. The plurality of nozzles 10 are arranged horizontally in a paper width direction (the "first direction" of the present invention) perpendicular to the transport direction to form a nozzle row 9. The head 11 also has two nozzle rows 9 aligned in the transport direction. The plurality of nozzles 10 constituting the nozzle row 9 on the upstream side in the transport direction and the plurality of nozzles 10 constituting the nozzle row 9 on the upstream side in the transport direction are offset in the paper width direction by half the length of the interval between the nozzles 10 in each nozzle row 9.

[0013] Furthermore, four of the eight heads 11 are aligned at intervals in the paper width direction. The remaining four of the eight heads 11 are aligned at intervals in the paper width direction at positions shifted downstream in the transport direction from the above four heads 11. The positions of the four heads 11 on the upstream side of the transport direction are shifted in the paper width direction from the four heads 11 on the downstream side. As a result, the multiple nozzles 10 of the eight heads 11 constituting one head unit 2 are arranged over the entire length of the recording paper P in the paper width direction.

[0014] The head holding member 12 is a rectangular plate-like member whose longitudinal direction is the paper width direction. The head holding member 12 holds the eight heads 11 in the above-mentioned positional relationship.

[0015] Furthermore, from the multiple nozzles 10 of the heads 11 constituting the four head units 2, black, yellow, cyan and magenta inks are ejected in that order from the head unit 2 constituting the upstream side in the transport direction.

[0016] The platen 3 is disposed below the four head units 2 and faces the multiple nozzles 10 of the four head units 2 in the vertical direction (the "second direction" of the present invention). The platen 3 extends across the entire length of the recording paper P in the paper width direction and across the four head units 2 in the transport direction, supporting the recording paper P from below.

[0017] The transport roller pair 4 is disposed upstream in the transport direction from the four head units 2. The transport roller pair 5 is disposed downstream in the transport direction from the four head units 2. Each of the transport roller pairs 4 and 5 is composed of two rollers aligned vertically, and transports the recording paper P in the transport direction by rotating with the recording paper P sandwiched between these two rollers.

[0018] In the printer 1, recording can be performed on the recording paper P by ejecting ink from multiple nozzles 10 of the eight heads 11 that make up each head unit 2 while transporting the recording paper P in the transport direction by a pair of transport rollers 4, 5.

[0019] <Head 11 Configuration> Next, we will explain the configuration of the head 11. As shown in Figures 2, 3(a), 3(b), and 4, the head 11 includes a flow path substrate 21, a nozzle plate 22, two damper plates 23, and a pressure chamber plate 24.

[0020] The flow path substrate 21 is a rectangular parallelepiped member made of silicon. The nozzle plate 22 is made of silicon and is disposed in the center of the lower surface of the flow path substrate 21 in the transport direction, and extends over substantially the entire length of the flow path substrate 21 in the paper width direction.

[0021] The two damper plates 23 are formed from a synthetic resin material or the like, and are disposed at the upstream and downstream ends in the transport direction on the lower surface of the flow path substrate 21, and extend in the paper width direction over almost the entire length of the flow path substrate 21. The damper plates 23 are thinner than the nozzle plate 22 etc., and suppress pressure fluctuations of ink in a first common flow path 36 described below by elastically deforming.

[0022] The pressure chamber plate 24 is made of silicon and is disposed on the upper surface of the flow path substrate 21. As a result, the pressure chamber plate 24 is disposed above the nozzle plate 22 ("one side in the second direction" of the present invention), and the flow path substrate 21 is disposed between the nozzle plate 22 and the pressure chamber plate 24.

[0023] In the laminate of the flow path substrate 21, the nozzle plate 22, the damper plate 23 and the pressure chamber plate 24, a plurality of nozzles 10, a plurality of pressure chambers 31, a plurality of descenders 32, a plurality of first orifices 33 and a plurality of second orifices 34 are formed.

[0024] The nozzles 10 are formed in the nozzle plate 22, forming the two nozzle rows 9 described above. The pressure chambers 31 are formed in the pressure chamber plate 24. The pressure chambers 31 are provided individually for the nozzles 10, and the inner ends in the transport direction overlap the corresponding nozzles 10 in the vertical direction. Furthermore, the shape of the pressure chambers 31 projected in the vertical direction is a parallelogram with the transport direction as the longitudinal direction and a pair of opposing sides parallel to the transport direction. Furthermore, the pressure chambers 31 are formed in a portion of the pressure chamber plate 24 excluding the upper end portion, and the portion of the upper end portion of the pressure chamber plate 24 that extends across the pressure chambers 31 serves as a vibration plate 24a that covers the pressure chambers 31.

[0025] The descenders 32 are formed on the flow path substrate 21. The descenders 32 are provided for each pair of corresponding nozzles 10 and pressure chambers 31. The descenders 32 extend through the flow path substrate 21 in the vertical direction, and connect the corresponding nozzles 10 and pressure chambers 31 to their inner ends in the transport direction.

[0026] Moreover, the shape of the descender 32 when projected in the vertical direction is a parallelogram, and inner wall surfaces 32a on both sides in the paper width direction, which form a pair of opposing sides of the parallelogram, are parallel to the transport direction.

[0027] The first apertures 33 are provided individually for the pressure chambers 31. The first apertures 33 extend in the vertical direction in the upper portion of the flow path substrate 21, and their upper ends are connected to the outer ends in the transport direction of the corresponding pressure chambers 31. Moreover, the shape of the first apertures 33 projected in the vertical direction is a parallelogram having a pair of opposing sides parallel to the transport direction.

[0028] The multiple second throttles 34 are provided individually for the multiple descenders 32. The second throttles 34 have a first flow path portion 34a and a second flow path portion 34b.

[0029] The first flow path portion 34a is formed in an upper portion of the nozzle plate 22. The first flow path portion 34a extends parallel to the transport direction, and an outer end in the transport direction is connected to the lower end of the corresponding descender 32.

[0030] The second flow path portion 34b is formed in a lower portion of the flow path substrate 21. The second flow path portion 34b extends in the transport direction. An outer end of the second flow path portion 34b in the transport direction is connected to an inner end of the first flow path portion 34a in the transport direction.

[0031] The second flow path portion 34b is formed in the lower portion of the flow path substrate 21. The ceiling surface 34b1 of the second flow path portion 34b has an inclined surface 34b2 and a connecting surface 34b3 in a cross section perpendicular to the paper width direction. The inclined surface 34b2 is inclined with respect to the transport direction so as to move upward toward the inside of the transport direction (closer to the second common flow path 37 described later). The connecting surface 34b3 is connected to the inner end of the inclined surface 34b2 in the transport direction. In addition, the angle K2 between the inclined surface 34b2 and the connecting surface 34b3 is an obtuse angle (for example, about 110 to 180°). Here, the connecting surface 34b3 may be, for example, a surface parallel to the transport direction. Alternatively, the connecting surface 343b may be inclined with respect to the transport direction so as to move upward toward the inside of the transport direction, and the inclination angle with respect to the transport direction may be smaller than that of the inclined surface.

[0032] In this embodiment, since the second throttle 34 has the above-described structure, the flow path resistance of the second throttle 34 formed by the first flow path portion 34a and the second flow path portion 34b is smaller than the flow path resistance of the nozzle 10. For example, when the flow path resistance of the nozzle 10 is 4×10 13 Pa·s / m 3 The flow resistance of the second throttle 34 is about 2×10 13 Pa·s / m 3That's about it.

[0033] In the head 11, an individual flow path 20 is formed by the corresponding nozzle 10, pressure chamber 31, descender 32, first throttle 33, and second throttle 34. In the head 11, the nozzles 10 form two nozzle rows 9, and correspondingly, the individual flow paths 20 are respectively formed by arranging in the paper width direction to form two individual flow path rows 19 aligned in the transport direction. In this embodiment, the combination of the second throttles 34 of the individual flow paths 20 constituting each individual flow path row 19 corresponds to the "connecting flow path" of the present invention.

[0034] In addition, in the laminate of the flow path substrate 21, the nozzle plate 22, the damper plate 23 and the pressure chamber plate 24, in addition to the multiple individual flow paths 20 as described above, two lower flow path portions 36a which are the lower portions of the two first common flow paths 36, and one lower flow path portion 37a which is the lower portion of one second common flow path 37 are formed.

[0035] The two lower flow path portions 36a are provided corresponding to the two individual flow path arrays 19. The lower flow path portions 36a are located outside the corresponding individual flow path arrays 19 in the transport direction. The lower flow path portions 36a extend in the paper width direction across the multiple individual flow paths 20 that constitute the corresponding individual flow path array 19. In addition, the lower flow path portions 36a, except for the outer ends in the transport direction, are formed in the lower portion of the flow path substrate 21, and the lower ends of the first throttles 33 of the multiple individual flow paths 20 that constitute each individual flow path array 19 are connected to the lower flow path portions 36a.

[0036] Moreover, the lower flow path portion 36a, at its outer end in the transport direction, extends vertically through the flow path substrate 21 and the pressure chamber plate 24. Moreover, the above-mentioned damper plate 23 forms the lower wall of the lower flow path portion 36a, and the elastic deformation of the damper plate 23 suppresses pressure fluctuations of the ink in the lower flow path portion 36a.

[0037] The lower flow path portion 37a is disposed between the two individual flow path rows 19 in the transport direction, and extends vertically through the flow path substrate 21 and the pressure chamber plate 24. As a result, the vertical length of the second flow path portion 34b is shorter than the vertical length of the second common flow path 37. The lower flow path portion 37a thus disposed overlaps with the descenders 32 in the transport direction, and a portion of the flow path substrate 21 located between the lower flow path portion 37a and the descenders 32 serves as a partition wall 21a separating the lower flow path portion 37a and the descenders 32. In addition, the inner end of the second flow path portion 34b in the transport direction of the multiple individual flow paths 20 constituting the two individual flow path rows 19 is connected to the lower flow path portion 37a.

[0038] Moreover, the head 11 includes, in addition to the flow path substrate 21, the nozzle plate 22, the damper plate 23, and the pressure chamber plate 24, two piezoelectric actuators 25, a protection substrate 26, and a cover member 27.

[0039] The two piezoelectric actuators 25 correspond to the two individual flow path rows 19. Each piezoelectric actuator 25 includes a piezoelectric layer 41, a common electrode 42, and a plurality of individual electrodes 43.

[0040] The piezoelectric layer 41 is formed of a piezoelectric material whose main component is lead zirconate titanate, which is a mixed crystal of lead titanate and lead zirconate, and is disposed on the upper surface of the pressure chamber plate 24 (vibration plate 24a) and extends in the paper width direction across the multiple pressure chambers 31 that constitute the corresponding individual flow path array 19.

[0041] The common electrode 42 extends over the entire area between the pressure chamber plate 24 (diaphragm 24a) and the piezoelectric layer 41. The common electrode 42 is connected to a power source (not shown) via wiring members (not shown) and is held at ground potential. The individual electrodes 43 are disposed on the upper surface of the piezoelectric layer 41. Each individual electrode 43 corresponds to one pressure chamber 31 and overlaps with the center of the corresponding pressure chamber 31 in the vertical direction. The individual electrodes 43 are connected to a driver IC (not shown) via wiring members (not shown). The driver IC selectively applies either ground potential or a predetermined drive potential (for example, about 20 to 30 V) to each of the individual electrodes 43.

[0042] In addition, in response to the common electrode 42 and the plurality of individual electrodes 43 being arranged in this manner, the portions of the piezoelectric layer 41 sandwiched between each individual electrode 43 and the common electrode 42 are polarized in the vertical direction.

[0043] Here, a method of ejecting ink from the nozzle 10 by the piezoelectric actuator 25 will be described. In the piezoelectric actuator 25, when ink is not ejected from the nozzles 10, a ground potential is applied to all the individual electrodes 43. When ink is ejected from a certain nozzle 10, the potential of the individual electrode 43 corresponding to that nozzle 10 is switched from the ground potential to a drive potential. Then, a vertical electric field parallel to the polarization direction is generated in a portion of the piezoelectric layer 41 sandwiched between the individual electrode 43 and the common electrode 42, and this electric field causes this portion of the piezoelectric layer 41 to contract in a horizontal direction (paper width direction and transport direction) perpendicular to the polarization direction. As a result, the vibration plate 24a and the piezoelectric layer 41 are deformed to be convex toward the pressure chamber 31. As a result, the volume of the pressure chamber 31 is reduced, and the pressure of the ink in the pressure chamber 31 increases, and ink is ejected from the nozzle 10 communicating with the pressure chamber 31. Furthermore, after the ink is ejected from the nozzle 10, the potential of the individual electrode 43 is returned from the drive potential to the ground potential, whereby the vibration plate 24a and the piezoelectric layer 41 return to their pre-deformation states.

[0044] The protective substrate 26 is made of silicon and is disposed on the upper surface of the pressure chamber plate 24 on which the two piezoelectric actuators 25 are disposed, covering the two piezoelectric actuators 25. More specifically, a recess 26a is formed on the lower surface of the protective substrate 26 in a portion that vertically overlaps with the two piezoelectric actuators 25. The piezoelectric actuator 25 is housed in the recess 26a.

[0045] The cover member 27 is disposed on the upper surface of the pressure chamber plate 24 on which the two piezoelectric actuators 25 and the protective substrate 26 are disposed, and covers the two piezoelectric actuators 25 and the protective substrate 26.

[0046] The cover member 27 is also formed with two upper flow passage portions 36b constituting the upper portions of the two first common flow passages 36. The upper flow passage portion 36b overlaps the lower flow passage portion 36a in the vertical direction and extends in the paper width direction over the entire length of the lower flow passage portion 36a. The upper flow passage portion 36b also extends in the vertical direction over a portion of the cover member 27 excluding the upper end portion. A connection port 36c extending to the upper end of the cover member 27 is also formed in the center of the upper flow passage portion 36b in the paper width direction.

[0047] The two connection ports 36c provided in the two first common flow paths 36 are connected to a pump 51a via a tube or the like (not shown). The pump 51a is connected to an ink tank 52. The pump 51a sends ink from the ink tank 52 toward the connection ports 36c.

[0048] Further, an upper flow passage portion 37b, which is an upper portion of the second common flow passage 37, is formed in the protective substrate 26 and the cover member 27. The upper flow passage portion 37b overlaps with the lower flow passage portion 37a in the vertical direction, and extends in the paper width direction over the entire length of the lower flow passage portion 37a. The upper flow passage portion 37b also extends in the vertical direction over a portion of the cover member 27 excluding its upper end portion and the protective substrate 26. Further, a connection port 37c extending to the upper end of the cover member 27 is formed in the center of the upper flow passage portion 37b in the paper width direction.

[0049] The connection port 37c is connected to a pump 51b via a tube (not shown) or the like. The pump 51b is also connected to an ink tank 52. The pump 51b sends ink from the connection port 37c toward the ink tank 52.

[0050] In this embodiment, when the pumps 51a and 51b are driven, the ink in the ink tank 52 flows from the two connection ports 36c into the two first common flow paths 36 via tubes (not shown) or the like. Furthermore, the ink that has flowed into the first common flow path 36 flows into the multiple individual flow paths 20 from the first throttle 33. The ink that has flowed into the multiple individual flow paths 20 flows out from the second throttle 34 into the second common flow path 37. The ink that has flowed into the second common flow path 37 flows out from the connection port 37c and returns to the ink tank 52 via tubes (not shown). In this way, in this embodiment, ink can be circulated between the head 11 and the ink tank 52.

[0051] It is to be noted that one of the pumps 51a and 51b may be omitted. Even in this case, by driving the other pump, ink can be circulated between the head 11 and the ink tank 52 in the same manner as described above.

[0052] <Effects> In this embodiment, the second restrictor 34 has a first flow path portion 34a formed in the nozzle plate 22 and a second flow path portion 34b formed in the flow path substrate 21, so that the length of the second restrictor 34 can be increased while reducing the flow path resistance of the second restrictor compared to when the entire second restrictor is formed in the nozzle plate 22. This makes it possible to smoothly discharge air in the ink from the descender 32 to the second common flow path 37, while ensuring the thickness (length in the transport direction) of the partition wall 21a between the descender 32 and the second common flow path 37, making it difficult for crosstalk to occur.

[0053] Furthermore, since the vertical length of the second flow path portion 34b is shorter than the vertical length of the second common flow path 37, the length of the first flow path portion 34a can be shortened while maintaining the thickness of the partition 21a between the descender 32 and the second common flow path 37, thereby preventing the flow path resistance of the second choke 34 from becoming unnecessarily large.

[0054] In this embodiment, the ceiling surface 34b1 of the second flow path portion 34b has an inclined surface 34b2 that extends at an angle with respect to the transport direction so as to face upward as it approaches the second common flow path 37. This allows air bubbles in the second flow path portion 34b to flow smoothly toward the second common flow path 37 along the inclined surface 34b2.

[0055] In this embodiment, the ceiling surface 34b1 of the second flow path portion 34b has an inclined surface 34b2 inclined with respect to the transport direction as described above, and a connection surface 34b3 connected to the end of the inclined surface 34b2 on the second common flow path 37 side in the transport direction, and the angle K2 formed by the inclined surface 34b2 and the connection surface 34b3 is an obtuse angle. This makes it possible to make it difficult for air bubbles to accumulate in the connection portion between the inclined surface 34b2 and the connection surface 34b3.

[0056] Moreover, in this embodiment, a plurality of second orifices 34 are provided individually for a plurality of descenders 32. This results in a configuration in which the descenders 32 communicate with each other only via the second common flow path 37. This makes it possible to prevent so-called fluid crosstalk from occurring, in which pressure applied by the piezoelectric actuator 25 to the ink in a certain pressure chamber 31 and transmitted to the ink in the corresponding second orifice 34 is transmitted to the ink in another pressure chamber 31 via the other second orifice 34.

[0057] In this embodiment, the flow path resistance of the second restrictor 34 is smaller than the flow path resistance of the nozzle 10. As a result, when the ink circulates between the head 11 and the ink tank 52, the ink flows more easily from the descender 32 to the second common flow path 37, and the ink is less likely to leak from the nozzle 10.

[0058] <Modification> Although the preferred embodiments of the present invention have been described above, the present invention is not limited to the above-mentioned embodiments, and various modifications are possible within the scope of the claims.

[0059] In the above embodiment, the flow path resistance of the second restrictor 34 is smaller than the flow path resistance of the nozzle 10, but this is not limited to this. For example, the flow path resistance of the second restrictor 34 may be equal to or greater than the flow path resistance of the nozzle 10, as long as the ink does not leak from the nozzle 10 when the ink circulates between the head 11 and the ink tank 52 as described above.

[0060] In addition, in the above-described embodiment, the ceiling surface 34b1 of the second flow path portion 34b has an inclined surface 34b2 inclined with respect to the transport direction (the length direction of the second flow path portion 34b) so as to face upward as it approaches the second common flow path 37 in the transport direction, and a connecting surface 34b3 connected to the end of the inclined surface 34b2 on the second common flow path 37 side in the transport direction, and the angle formed between the inclined surface 34b2 and the connecting surface 34b3 is an obtuse angle, but this is not limited to this.

[0061] For example, the ceiling surface 34b1 may not have the connecting surface 34b3, and the inclined surface 34b2 may extend to the end of the second flow path portion 34b on the second common flow path 37 side in the transport direction.

[0062] Alternatively, for example, the ceiling surface 34b1 may extend parallel to the transport direction over the entire length of the second flow path portion 34b in the transport direction.

[0063] In addition, in the above embodiment, the second flow path portions 34b are provided individually for the multiple first flow path portions 34a, but this is not limiting.

[0064] 5, in the first modification, a second flow path portion 101 is provided for each pair of first flow path portions 34a adjacent to each other in the paper width direction. Each second flow path portion 101 extends in the paper width direction across the corresponding pair of first flow path portions 34a, and connects these two first flow path portions 34a to the second common flow path 37. In the first modification, a combination of the plurality of first flow path portions 34a and the plurality of second flow path portions 101 corresponding to each individual flow path array 19 corresponds to a "connecting flow path" of the present invention.

[0065] In the first modification, the flow path resistance of the connection flow path can be made smaller than in the above embodiment. This allows the ink to flow smoothly from the descender 32 to the second common flow path 37 when circulating between the head 11 and the ink tank 52.

[0066] In addition, in the first modified example, the second flow path portion 101 was provided for every two first flow path portions 34a adjacent in the paper width direction, but the second flow path portion may be provided for every some of three or more first flow path portions 34a adjacent in the paper width direction.

[0067] 6, in the second modification, one second flow path portion 111 is provided for each of the first flow path portions 34a of the individual flow paths 20 constituting each individual flow path array 19, and the second flow path portion 111 extends in the paper width direction across all of the first flow path portions 34a of the individual flow paths 20 constituting the corresponding individual flow path array 19, and connects these first flow path portions 34a to the second common flow path 37. In the second modification, the combination of the multiple first flow path portions 34a corresponding to each individual flow path array 19 and one second flow path portion 111 corresponds to the "connecting flow path" of the present invention.

[0068] In the modified example 2, the flow path resistance of the connecting flow path can be further reduced compared to the modified example 1. This allows the ink to flow smoothly from the descender 32 to the second common flow path 37 when circulating between the head 11 and the ink tank 52.

[0069] In the above-described embodiment, modified example 1, and modified example 2, the first flow path portion 34a formed in the nozzle plate 22 is connected to the descender 32, and the second flow path portions 34b, 101, and 111 formed in the flow path substrate 21 are connected to the second common flow path 37. This allows the second flow path portion to be individual for each descender 32 as in the above-described embodiment, or to be common to two or more descenders 32 as in modified example 1 and modified example 2. This allows for a higher degree of freedom in designing the second flow path portion compared to the case where the second flow path portion is connected to the descender 32 as in modified example 3 described later.

[0070] In addition, in the above example, the first flow path portion formed in the nozzle plate 22 is connected to the descender 32, and the second flow path portion formed in the flow path substrate 21 is connected to the second common flow path 37, but this is not limited to this.

[0071] In the third modification, as shown in Fig. 7(a), (b) and Fig. 8, a plurality of second throttles 121 are provided for a plurality of descenders 32. In the third modification, the plurality of second throttles 121 corresponding to each individual flow path row 19 respectively correspond to a "connection flow path" of the present invention. Each of the second throttles 121 has a first flow path portion 121a and a second flow path portion 121b.

[0072] The first flow path portion 121a is formed in an upper portion of the nozzle plate 22. The first flow path portion 121a extends parallel to the transport direction, and an inner end in the transport direction is connected to the second common flow path 37.

[0073] The second flow path portion 121b is formed in a lower portion of the flow path substrate 21. The second flow path portion 121b extends in the transport direction. An inner end of the second flow path portion 121b in the transport direction is connected to an outer end of the first flow path portion 121a in the transport direction. In addition, an outer end of the second flow path portion 121b in the transport direction is connected to an inner end of the lower end of the corresponding descender 32 in the transport direction.

[0074] Also in the third modification, the thickness of the partition wall 21a between the descender 32 and the second common flow path 37 is ensured to make it difficult for crosstalk to occur, while the flow path resistance of the second throttle 121 can be reduced.

[0075] In the above embodiment, the first throttle 33 is formed in the flow path substrate 21, and the first common flow path 36 is formed across the flow path substrate 21, the pressure chamber plate 24, and the cover member 27. However, this is not limited to this. For example, the first throttle 33 may be formed in the pressure chamber plate 24, and the first common flow path 36 may be formed only across the pressure chamber plate 24 and the cover member 27.

[0076] In the above embodiment, the second flow path portion 34b formed in the flow path substrate 21 extends parallel to the transport direction, but this is not limiting.

[0077] In the fourth modification, the direction of the normal vector of the (110) crystal orientation of the flow path substrate 21 made of silicon is parallel to the vertical direction. In the fourth modification, as shown in FIG. 9, the second throttle 131 has a first flow path portion 131a and a second flow path portion 131b. The first flow path portion 131a is similar to the first flow path portion 34a of the above-mentioned embodiment. The second flow path portion 131b extends in an inclined direction inclined at an angle K1 with respect to the transport direction so as to move toward the right side of the paper width direction as it moves toward the upstream side of the transport direction. The angle K1 is, for example, about 55°. The outer end of the inclined direction of the second flow path portion 131b is connected to the inner end of the first flow path portion 131a in the transport direction. The inner end of the inclined direction of the second flow path portion 131b is connected to the second common flow path 37.

[0078] In the fourth modification, the flow path substrate 21 is made of silicon, and the direction of the normal vector of the (110) crystal orientation of the flow path substrate 21 is parallel to the vertical direction. On the other hand, the descender 32 that penetrates the flow path substrate 21 in the vertical direction has an inner wall surface 32a that is parallel to the transport direction, while the second flow path portion 34b formed in the flow path substrate 21 extends in an inclined direction inclined at an angle K1 with respect to the transport direction. The angle K1 is about 55°. As a result, the descender 32 and the second flow path portion 131b can be formed by wet etching, and further, when the second flow path portion 131b is formed by wet etching, the (111) crystal orientation of the flow path substrate 21 becomes a stopper surface for wet etching. As a result, the second flow path portion 131b can be easily formed at low cost.

[0079] In addition, in the fourth modified example, the direction of the normal vector of the (110) crystal orientation plane of the flow path substrate 21 formed of silicon is parallel to the vertical direction, and the second flow path portion 131b of the second aperture 131 extends at an angle of 55° with respect to the transport direction, but this is not limited to this.

[0080] For example, the second flow path portion 131b may extend at a different angle in the range of 50 to 60° with respect to the transport direction.

[0081] Alternatively, the flow path substrate 21 may be arranged such that the direction of the normal vector of the (110) crystal orientation plane is different from the direction parallel to the vertical direction. Even in this case, the descender 32 that penetrates the flow path substrate 21 in the vertical direction has an inner wall surface parallel to the transport direction, and the direction of each plane of the crystal orientation of the flow path substrate 21 and the inclination angle of the second flow path portion 131b with respect to the transport direction are appropriately set, whereby the second flow path portion 131b can be formed with high accuracy according to the crystal orientation of the flow path substrate 21.

[0082] In the above, an example has been described in which the present invention is applied to a head that ejects ink from nozzles, but the present invention is not limited to this. The present invention can also be applied to a liquid ejection head that ejects liquids other than ink. [Explanation of symbols]

[0083] 10 Nozzles 11 Head 21 Flow channel substrate 21a Bulkhead 22 Nozzle plate 24 Pressure chamber plate 31 Pressure Chamber 32 Descendant 34 2nd aperture 34a First flow path portion 34b Second flow path portion 34b1 Ceiling surface 34b2 Slope 34b3 Connection surface 36 First common flow path 37 Second common flow path 101 Second flow path portion 111 Second flow path part 121 2nd aperture 121a first flow path portion 121b second flow path portion 131 2nd aperture 131a first flow path portion 132b second flow path portion

Claims

1. a plurality of nozzles formed in a nozzle plate and arranged in a first direction; a pressure chamber plate disposed on one side of the nozzle plate in a second direction perpendicular to the first direction, the pressure chambers being provided individually for a plurality of nozzles and arranged in the first direction; a plurality of descenders that are formed on a flow path substrate disposed between the nozzle plate and the pressure chamber plate in the second direction, that are arranged in the first direction, and that extend in the second direction to connect the corresponding nozzles and the pressure chambers; a first common flow channel connected to the plurality of pressure chambers; a second common flow path formed in the flow path substrate, overlapping with the plurality of descenders in a third direction perpendicular to both the first direction and the second direction, and separated from the plurality of descenders by a partition wall formed by the flow path substrate; A connection flow path that connects the plurality of descenders and the second common flow path, The connecting flow path is a plurality of first flow path portions formed in the nozzle plate, each of which is provided for each of the plurality of descenders and connected to a corresponding one of the descenders; a second flow path portion that is formed on the flow path substrate, is connected to the first flow path portion and the second common flow path, and has a length in the second direction shorter than that of the second common flow path, The second direction is a vertical direction, the second flow path portion is connected to an end surface of the second common flow path in the third direction, a ceiling surface which is an inner wall surface on an upper side of the second flow path portion has an inclined surface which is inclined with respect to a longitudinal direction of the second flow path portion so as to be inclined upward as it approaches the second common flow path in the longitudinal direction of the second flow path portion, The ceiling surface is a connection surface connected to an end of the inclined surface on the second common flow path side in the third direction, A liquid ejection head, wherein the angle between the inclined surface and the connecting surface is an obtuse angle.

2. a plurality of nozzles formed in a nozzle plate and arranged in a first direction; a pressure chamber plate disposed on one side of the nozzle plate in a second direction perpendicular to the first direction, the pressure chambers being provided individually for a plurality of nozzles and arranged in the first direction; a plurality of descenders that are formed on a flow path substrate disposed between the nozzle plate and the pressure chamber plate in the second direction, that are arranged in the first direction, and that extend in the second direction to connect the corresponding nozzles and the pressure chambers; a first common flow channel connected to the plurality of pressure chambers; a second common flow path formed in the flow path substrate, overlapping with the plurality of descenders in a third direction perpendicular to both the first direction and the second direction, and separated from the plurality of descenders by a partition wall formed by the flow path substrate; A connection flow path that connects the plurality of descenders and the second common flow path, The connecting flow path is a plurality of first flow path portions formed in the nozzle plate, each of which is provided for each of the plurality of descenders and connected to a corresponding one of the descenders; a second flow path portion formed on the flow path substrate, extending in the first direction across two or more adjacent first flow path portions among the plurality of first flow path portions, connected to the two or more first flow path portions and the second common flow path, and having a length in the second direction shorter than that of the second common flow path.

3. The second direction is a vertical direction, the second flow path portion is connected to an end surface of the second common flow path in the third direction, A liquid ejection head as described in claim 2, characterized in that the ceiling surface, which is the upper inner wall surface of the second flow path portion, has an inclined surface that is inclined with respect to the longitudinal direction of the second flow path portion so as to become upward as it approaches the second common flow path in the longitudinal direction of the second flow path portion.

4. The ceiling surface is a connection surface connected to an end of the inclined surface on the second common flow path side in the third direction, 4. The liquid ejection head according to claim 3, wherein the angle between the inclined surface and the connecting surface is an obtuse angle.

5. The connecting flow path is The liquid ejection head according to claim 1 , further comprising a plurality of the second flow path portions provided individually for a plurality of the first flow path portions.

6. 6. The liquid ejection head according to claim 5, wherein a flow path resistance of a flow path formed by one of the first flow path portions and the second flow path portion corresponding to the first flow path portion is smaller than a flow path resistance of the nozzle.

7. The connecting flow path is A liquid ejection head as described in claim 1, characterized in that the second flow path portion extends in the first direction across two or more adjacent first flow path portions among the plurality of first flow path portions and is connected to the two or more first flow path portions.

8. The second flow path portion is 8. The liquid ejection head according to claim 2, wherein the nozzle extends in the first direction across all of the first flow path portions aligned in the first direction and is connected to all of the first flow path portions.

9. 9. The liquid ejection head according to claim 1, wherein the flow path substrate is made of silicon.

10. The descender is penetrating the flow path substrate in the second direction, an inner wall surface parallel to the third direction; 10. The liquid ejection head according to claim 9, wherein the second flow path portion extends in a direction inclined with respect to the third direction.

11. a direction of a normal vector of a (110) plane of the crystal orientation of the flow channel substrate is parallel to the second direction; 11. The liquid ejection head according to claim 10, wherein the second flow path portion extends in a direction inclined at an angle of 50 to 60 degrees with respect to the third direction.

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