Liquid ejection head and recording device using same

Abstract

To provide a liquid ejection head in which temperature difference can be made small, and a recording device using the same.SOLUTION: A liquid ejection head according to the present invention includes a first flow passage member 4 having a plurality of ejection holes 8 and a plurality of pressurizing chambers 10, a second flow passage member 6 which is laminated on the first flow passage member 4, and has a first integrated flow passage 22 and a second integrated flow passage 26, and a plurality of pressurizing portions 50. In a planar view, the first integrated flow passage part 22 is arranged in a more first direction side than a pressurizing chamber arrangement area 11C and extends in a second direction and includes a first end portion 22h at an end in the second direction, and the second integrated flow passage part 26 is arranged in a more third direction side than the pressurizing chamber arrangement area 11C and extends in a fourth direction, and includes a second end portion 26h at an end portion in the fourth direction. The first flow passage member 4 is joined to the second flow passage member 6, below the first end portion 22h and the second end portion 26h.SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] The present invention relates to a liquid ejection head and a recording apparatus using the same. [Background technology]

[0002] Conventionally, as a printing head, for example, a liquid ejection head that performs various printing by ejecting liquid onto a recording medium is known. A liquid ejection head is known that includes, for example, an ejection hole that ejects liquid, a pressure chamber that pressurizes the liquid so that the liquid is ejected from the ejection hole, a first common flow path that supplies the liquid to the pressure chamber, and a second common flow path that recovers the liquid from the pressure chamber. In order to prevent the liquid from stagnating and causing clogging of the flow path, even when ejection is not performed, the liquid flows from the first common flow path through the pressure chamber to the second common flow path, and is known to circulate the liquid including the outside. In addition, in such a liquid ejection head, it is known that a plurality of first common flow paths and a plurality of second common flow paths are formed in a shape that extends in the short direction of the liquid ejection head and are arranged alternately in the long direction of the liquid ejection head (for example, see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2009-143168 A Summary of the Invention [Problem to be solved by the invention]

[0004] In a liquid ejection head as described in Patent Document 1, the pressure chamber connected to the first common flow path or the second common flow path located at the end of the liquid ejection head in the longitudinal direction is more susceptible to the temperature of the external environment than a pressure chamber located in the center of the liquid ejection head in the longitudinal direction.Since the characteristics of liquid (for example, viscosity) basically have temperature characteristics, if there is a temperature difference in the liquid inside the pressure chamber, a difference occurs in the ejection characteristics (ejection amount and ejection speed) of the liquid ejected from the pressure chamber, resulting in a problem of poor recording accuracy.

[0005] SUMMARY OF THE PRESENT EMBODIMENT An object of the present invention is to provide a liquid ejection head capable of reducing the temperature difference inside the liquid ejection head, and a recording apparatus using the same. [Means for solving the problem]

[0006] A liquid ejection head according to the present invention includes a first flow path member having a plurality of ejection holes and a plurality of pressure chambers each connected to the plurality of ejection holes, a second flow path member laminated on the first flow path member, the second flow path member having a first unified flow path for recovering liquid from the plurality of pressure chambers and a second unified flow path for supplying liquid to the plurality of pressure chambers, and a plurality of pressurizing units for pressurizing the plurality of pressure chambers, respectively, wherein, in a plan view, the plurality of pressure chambers are arranged in a pressure chamber arrangement area, and the first unified flow path is arranged in a first direction further from the pressure chamber arrangement area, extends in a second direction intersecting the first direction, and is arranged in the second direction further from the pressure chamber arrangement area. the second integrated flow path is disposed in a third direction opposite to the first direction from the pressure chamber arrangement region, the second integrated flow path extends in a fourth direction opposite to the second direction from the pressure chamber arrangement region, and includes a second end flow path disposed in the fourth direction from the pressure chamber arrangement region, and either the first flow path member and the second flow path member are joined below the first end, or an upper surface of the first flow path member forms a lower surface of the first end, and either the first flow path member and the second flow path member are joined below the second end, or an upper surface of the first flow path member forms a lower surface of the second end. It is characterized by:

[0007] Furthermore, the liquid ejection head of the present invention is a liquid ejection head including a flow path member having a plurality of ejection holes, a plurality of pressure chambers each connected to the plurality of ejection holes, a first integrated flow path for recovering liquid from the plurality of pressure chambers, and a second integrated flow path for supplying liquid to the plurality of pressure chambers, and a plurality of pressurizing sections for pressurizing the plurality of pressure chambers, respectively, and is characterized in that, when viewed in a plane, the plurality of pressure chambers are arranged in a pressure chamber arrangement area, and within the plane, the first integrated flow path is arranged in a first direction further than the pressure chamber arrangement area, extends in a second direction intersecting the first direction, and includes a first end flow path arranged in the second direction further than the pressure chamber arrangement area, and the second integrated flow path is arranged in a third direction that is opposite to the first direction, further than the pressure chamber arrangement area, extends in a fourth direction that is opposite to the two directions, and includes a second end flow path arranged in the fourth direction further than the pressure chamber arrangement area.

[0008] Furthermore, the recording apparatus of the present invention is characterized by comprising the liquid ejection head, a transport unit that transports a recording medium to the liquid ejection head, and a control unit that controls the liquid ejection head. Effect of the Invention

[0009] According to the liquid ejection head of the present invention, the temperature difference inside the liquid ejection head can be reduced. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1A is a side view of a recording apparatus including a liquid ejection head according to an embodiment of the present invention, and FIG. [Diagram 2] 2A is a plan view of a head main body which is a main part of the liquid ejection head in FIG. 1, and FIG. 2B is a plan view of FIG. 2A from which a second flow path member has been removed. [Diagram 3] FIG. 3 is an enlarged plan view of a portion of FIG. [Figure 4] FIG. 3 is an enlarged plan view of a portion of FIG. [Diagram 5]2(a) is a partial vertical cross-sectional view taken along line VV in FIG. 4, and FIG. 2(b) is a partial vertical cross-sectional view of the head main body in FIG. 2(a). [Figure 6] FIG. 2(a) is a schematic plan view of FIG. 2(a), and (b) and (c) are schematic plan views of a liquid ejection head according to another embodiment of the present invention. [Figure 7] 10(a) to 10(c) are schematic plan views of a liquid ejection head according to another embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Fig. 1(a) is a schematic side view of a (color inkjet) printer 1, which is a recording device including a liquid ejection head 2 according to one embodiment of the present invention, and Fig. 1(b) is a schematic plan view. The printer 1 moves the printing paper P, which is a recording medium, relative to the liquid ejection head 2 by transporting the printing paper P from transport rollers 80A to transport rollers 80B. A control unit 88 controls the liquid ejection head 2 based on image and character data to eject liquid toward the recording medium P and cause droplets to land on the printing paper P, thereby performing recording such as printing on the printing paper P.

[0012] In this embodiment, the liquid ejection head 2 is fixed to the printer 1, which is a so-called line printer. Another embodiment of the recording device of the present invention is a so-called serial printer, which alternates between moving the liquid ejection head 2 back and forth in a direction intersecting the transport direction of the print paper P, for example, in a direction substantially perpendicular thereto, and transporting the print paper P.

[0013] A flat (head-mounted) frame 70 is fixed to the printer 1 so as to be approximately parallel to the printing paper P. The frame 70 is provided with 20 holes (not shown), and 20 liquid ejection heads 2 are mounted on the respective holes, so that the portions of the liquid ejection heads 2 that eject liquid face the printing paper P. The distance between the liquid ejection heads 2 and the printing paper P is, for example, about 0.5 to 20 mm. The five liquid ejection heads 2 make up one head group 72, and the printer 1 has four head groups 72.

[0014] The liquid ejection head 2 has a long, narrow shape extending from the front to the back in FIG. 1(a) and vertically in FIG. 1(b). This long direction is sometimes called the longitudinal direction. In one head group 72, three liquid ejection heads 2 are arranged in a direction intersecting the transport direction of the printing paper P, for example, in a direction substantially perpendicular thereto, and the other two liquid ejection heads 2 are arranged one by one between the three liquid ejection heads 2 at positions shifted along the transport direction. The liquid ejection heads 2 are arranged so that the printable range of each liquid ejection head 2 is connected in the width direction of the printing paper P (in the direction intersecting the transport direction of the printing paper P) or so that the ends overlap, making it possible to print without gaps in the width direction of the printing paper P.

[0015] The four head groups 72 are arranged along the transport direction of the recording paper P. Each liquid ejection head 2 is supplied with liquid (ink) from a liquid tank (not shown). The liquid ejection heads 2 belonging to one head group 72 are supplied with ink of the same color, and the four head groups can print with four colors of ink. The colors of ink ejected from each head group 72 are, for example, magenta (M), yellow (Y), cyan (C), and black (K). If such inks are controlled by the control unit 88 for printing, a color image can be printed.

[0016] The number of liquid ejection heads 2 mounted on the printer 1 may be one if printing is performed in a single color within a range that can be printed with one liquid ejection head 2. The number of liquid ejection heads 2 included in the head group 72 and the number of head groups 72 can be changed as appropriate depending on the object to be printed and the printing conditions. For example, the number of head groups 72 may be increased to print in more colors. In addition, the printing speed (transport speed) can be increased by arranging multiple head groups 72 that print in the same color and printing alternately in the transport direction. In addition, the resolution in the width direction of the printing paper P may be increased by preparing multiple head groups 72 that print in the same color and arranging them offset in a direction intersecting the transport direction.

[0017] Furthermore, in addition to printing colored ink, in order to treat the surface of the printing paper P, a liquid such as a coating agent may be printed.

[0018] The printer 1 prints on a printing paper P, which is a recording medium. The printing paper P is wound around a paper feed roller 80A, passes between two guide rollers 82A, passes under the liquid ejection head 2 mounted on the frame 70, then passes between two transport rollers 82B, and is finally collected by a recovery roller 80B. When printing, the printing paper P is transported at a constant speed by rotating the transport roller 82B, and is printed by the liquid ejection head 2. The recovery roller 80B winds up the printing paper P sent out from the transport roller 82B. The transport speed is, for example, 50 m / min. Each roller may be controlled by a control unit 88, or may be operated manually by a person.

[0019] The recording medium may be a cloth or the like in addition to the printing paper P. The printer 1 may be configured to convey a conveyor belt instead of the printing paper P, and the recording medium may be a roll or a sheet of paper, cut cloth, wood, tile, or the like placed on the conveyor belt. Furthermore, a liquid containing conductive particles may be ejected from the liquid ejection head 2 to print wiring patterns for electronic devices. Furthermore, a chemical agent or a liquid containing a chemical agent may be ejected from the liquid ejection head 2 into a reaction vessel or the like in a predetermined amount, and the chemical agent may be reacted to form a liquid. Products may also be produced.

[0020] Furthermore, the printer 1 may be equipped with position sensors, speed sensors, temperature sensors, etc., and the control unit 88 may control each part of the printer 1 according to the state of each part of the printer 1 determined from information from each sensor. In particular, if the ejection characteristics (ejection amount, ejection speed, etc.) of the liquid ejected from the liquid ejection head 2 are subject to external influences, the drive signal for ejecting the liquid from the liquid ejection head 2 may be changed according to the temperature of the liquid ejection head 2, the temperature of the liquid in the liquid tank, and the pressure applied to the liquid ejection head 2 by the liquid in the liquid tank.

[0021] Next, a liquid ejection head 2 according to an embodiment of the present invention will be described. Fig. 2(a) is a plan view showing a head main body 2a which is a main part of the liquid ejection head 2 shown in Fig. 1. Fig. 2(b) is a plan view showing a state in which the second flow path member 6 is removed from the head main body 2a. Figs. 3 and 4 are enlarged plan views of Fig. 2(b). Fig. 5(a) is a vertical cross-sectional view taken along line VV in Fig. 4. Fig. 5(b) is a partial vertical cross-sectional view taken along the first common flow path 20 in the vicinity of an opening 20a of the first common flow path 20 of the head main body 2a. Fig. 6(a) is a schematic plan view of the head main body 2a shown in Fig. 2(a).

[0022] In order to make the drawings easier to understand, the drawings are drawn as follows. In Figures 2 to 4, flow paths that are below other objects and should be drawn in dashed lines are drawn in solid lines. In Figure 2(a), most of the flow paths in the first flow path member 4 are omitted, and only the arrangement of the pressurizing chambers 10 is shown.

[0023] The liquid ejection head 2 may include a metal housing, a driver IC, a wiring board, and the like, in addition to the head main body 2a. The head main body 2a also includes a first flow path member 4, a second flow path member 6 that supplies liquid to the first flow path member 4, and a piezoelectric actuator substrate 40 on which a displacement element 50, which is a pressure applying section, is built. The head main body 2a has a flat plate shape that is long in one direction, which may be referred to as the longitudinal direction. The second flow path member 6 also serves as a support member, and the head main body 2a is fixed to a frame 70 at both ends of the second flow path member 6 in the longitudinal direction.

[0024] The first flow path member 4 constituting the head main body 2a has a flat plate shape and a thickness of about 0.5 to 2 mm. A large number of pressure chambers 10 are arranged in a plane on a pressure chamber surface 4-1, which is a first main surface of the first flow path member 4. A large number of discharge holes 8 from which liquid is discharged are arranged in a plane on a discharge hole surface 4-2, which is a second main surface of the first flow path member 4. Each discharge hole 8 is connected to a pressure chamber 10. In the following description, the pressure chamber surface 4-1 is assumed to be located above the discharge hole surface 4-2.

[0025] In the first flow path member 4, a plurality of first common flow paths 20 and a plurality of second common flow paths 24 are arranged to extend along a first direction. Moreover, the first common flow paths 20 and the second common flow paths 24 are arranged alternately in a second direction that intersects with the first direction.

[0026] The pressure chambers 10 are arranged along both sides of the first common flow path 20, forming one row on each side, i.e., two rows of pressure chambers 11A in total. The first common flow path 20 and the pressure chambers 10 arranged on both sides of the first common flow path 20 are connected via first individual flow paths 12.

[0027] The pressure chambers 10 are arranged along both sides of the second common flow path 24, forming one row on each side, thus constituting a total of two rows of pressure chambers 11A. The first integrated flow path 22 and the pressure chambers 10 arranged on both sides thereof are connected via second individual flow paths 14. In the following, the first common flow path 20 and the second common flow path 24 may be collectively referred to as a common flow path.

[0028] In other words, the pressure chambers 10 are arranged side by side on an imaginary line, and on one side of the imaginary line The first common flow path 20 extends along the imaginary line, and the second common flow path 24 extends along the other side of the imaginary line. In this embodiment, the imaginary line along which the pressure chambers 10 are arranged is a straight line, but it may be a curved line or a broken line.

[0029] With the above-described configuration, in the first flow path member 4, the liquid supplied to the second common flow path 24 flows into the pressure chambers 10 arranged along the second common flow path 24, and some of the liquid is ejected from the ejection holes 8, while another portion of the liquid flows into the first common flow path 20 located on the opposite side of the pressure chambers 10 from the second common flow path 24, and is discharged from the first flow path member 4 to the outside.

[0030] By arranging the second common flow paths 24 on both sides of the first common flow path 20 and the first common flow paths 20 on both sides of the second common flow path 24, one first common flow path 20 and one second common flow path 24 are connected to one pressurizing chamber row 11A, and compared to a case in which another first common flow path 20 and another second common flow path 24 are connected to another pressurizing chamber row 11A, the number of the first common flow paths 20 and the second common flow paths 24 can be reduced by about half, which is preferable. Since the number of the first common flow paths 20 and the second common flow paths 24 is reduced, it is possible to increase the number of pressurizing chambers 10 to increase the resolution, to widen the first common flow paths 20 and the second common flow paths 24 to reduce the difference in the ejection characteristics from the ejection holes 8, and to reduce the size of the head main body 2a in the planar direction.

[0031] The pressure applied to the portion of the first individual flow passage 12 connected to the first common flow passage 20 on the first common flow passage 20 side varies depending on the position of the first individual flow passage 12 in the first common flow passage 20 due to the influence of pressure loss. The pressure applied to the portion of the second individual flow passage 14 connected to the second common flow passage 24 varies depending on the position of the second individual flow passage 14 in the second common flow passage 24 due to the influence of pressure loss. If the opening 20a to the outside of the first common flow passage 20 is arranged at one end in the first direction and the opening 24a to the outside of the second common flow passage 24 is arranged at the other end in the first direction, the pressure difference due to the arrangement of each first individual flow passage 12 and each second individual flow passage 14 acts to cancel out, and the difference in pressure applied to each discharge hole 8 can be reduced. Note that both the opening 20a of the first common flow passage 20 and the opening 24a of the second common flow passage 24 open to the pressurized chamber surface 4-1.

[0032] When not being ejected, a meniscus of the liquid is maintained in the ejection hole 8. As the pressure of the liquid in the ejection hole 8 is negative (a state in which the liquid is drawn into the first flow path member 4), it balances with the surface tension of the liquid and the meniscus can be maintained. If the positive pressure becomes too large, the liquid will overflow, and if the negative pressure becomes too large, the liquid will be drawn into the first flow path member 4, making it impossible to maintain a state in which the liquid can be ejected. For this reason, it is necessary to prevent the difference in pressure of the liquid in the ejection hole 8 from becoming too large when the liquid is flowed from the second common flow path 24 to the first common flow path 20.

[0033] The wall surface of the first common flow path 20 on the discharge hole surface 4-2 side is the first damper 28A. One surface of the first damper 28A faces the first common flow path 20, and the other surface faces the damper chamber 29. The damper chamber 29 allows the first damper 28A to be deformed, and the volume of the first common flow path 20 can be changed by deforming it. When the liquid in the pressurizing chamber 10 is pressurized to discharge the liquid, part of the pressure is transmitted to the first common flow path 20 through the liquid. This causes the liquid in the first common flow path 20 to vibrate, and the vibration is transmitted to the original pressurizing chamber 10 or another pressurizing chamber 10, which may cause fluid crosstalk that changes the discharge characteristics of the liquid. If the first damper 28A exists, the vibration of the liquid transmitted to the first common flow path 20 causes the first damper 28A to vibrate, and by damping, the vibration of the liquid in the first common flow path 20 is less likely to be sustained, so that the effect of fluid crosstalk can be reduced. The first damper 28A also serves to stabilize the supply and discharge of liquid.

[0034] The wall surface of the second common flow passage 24 on the side of the pressurizing chamber surface 4-1 is a second damper 28B. One surface of the second damper 28B faces the second common flow passage 24, and the other surface faces the damper chamber 29. The second damper 28B also reduces the influence of fluid crosstalk, similar to the first damper 28A. The second damper 28B also serves to stabilize the supply and discharge of liquid.

[0035] The pressurizing chamber 10 is disposed facing the pressurizing chamber surface 4-1, and is a hollow region including the pressurizing chamber main body 10a that receives pressure from the displacement element 50, and the descender 10b that is a partial flow path that connects to the discharge hole 8 that opens from the bottom of the pressurizing chamber main body 10a to the discharge hole surface 4-2. The pressurizing chamber main body 10a has a right circular cylindrical shape and a circular planar shape. The circular planar shape can increase the amount of displacement when the displacement element 50 is deformed by the same force, and the volume change of the pressurizing chamber 10 caused by the displacement. The descender 10b has a right circular cylindrical shape with a smaller diameter than the pressurizing chamber main body 10a, and a circular cross-sectional shape. The descender 10b is disposed at a position that fits within the pressurizing chamber main body 10a when viewed from the pressurizing chamber surface 4-1.

[0036] The multiple pressure chambers 10 are arranged in a staggered manner on the pressure chamber surface 4-1. The multiple pressure chambers 10 form multiple pressure chamber rows 11A along the first direction. In each pressure chamber row 11A, the pressure chambers 10 are arranged at approximately equal intervals. The pressure chambers 10 belonging to adjacent pressure chamber rows 11A are arranged with a shift of half the interval in the first direction. In other words, the pressure chamber 10 belonging to a certain pressure chamber row 11A is located approximately in the center in the first direction with respect to two consecutive pressure chambers 10 belonging to the adjacent pressure chamber row 11A.

[0037] As a result, the pressure chambers 10 belonging to every other pressure chamber column 11A are arranged along the second direction, and form pressure chamber rows 11B.

[0038] In this embodiment, there are 51 first common flow paths 20, 50 second common flow paths 24, and 100 pressurizing chamber rows 11A. (Here, the dummy pressurizing chamber rows 11D consisting only of dummy pressurizing chambers 10D described below are not included in the number of pressurizing chamber rows 11A described above. Also, the second common flow paths 24 that are directly connected only to the dummy pressurizing chambers 10D are not included in the number of second common flow paths 24 described above.) Also, each pressurizing chamber row 11A includes 16 pressurizing chambers 10. As described above, the pressurizing chambers 10 are arranged in a staggered pattern, so the number of pressurizing chamber rows 11B is 32.

[0039] The multiple pressure chambers 10 are arranged in a lattice pattern along the first and second directions on the discharge hole surface 4-2. The multiple discharge holes 8 form multiple discharge hole rows 9A along the first direction. The discharge hole rows 9A and the pressure chamber rows 11A are arranged at approximately the same position.

[0040] The area center of gravity of the pressurizing chambers 10 and the discharge holes 8 connected to the pressurizing chambers 10 are arranged to be shifted in the first direction. In one pressurizing chamber row 11A, the shift direction is the same, and in adjacent pressurizing chamber rows 11A, the shift direction is opposite. As a result, the discharge holes 8 connected to the pressurizing chambers 10 belonging to two pressurizing chamber rows 11B constitute one discharge hole row 9B arranged along the second direction.

[0041] Therefore, in this embodiment, there are 100 ejection hole columns 9A and 16 ejection hole rows 9B.

[0042] The area center of gravity of the pressurizing chamber body 10a and the discharge hole 8 connected to the pressurizing chamber body 10a are offset in position in the first direction. The descender 10b is disposed at a position offset from the pressurizing chamber body 10a toward the discharge hole 8. The side walls of the pressurizing chamber body 10a and the descender 10b are disposed so as to be in contact with each other, which makes it difficult for liquid to stagnate within the pressurizing chamber body 10a.

[0043] The discharge hole 8 is disposed in the center of the descender 10b. This refers to the area within a circle having a diameter half that of the descender 10b and centered at the center of gravity of the descender 10b.

[0044] The connection between the first individual flow path 12 and the pressurizing chamber body 10a is disposed on the opposite side of the descender 10b with respect to the area center of gravity of the pressurizing chamber body 10a. As a result, the liquid flowing in from the descender 10b spreads over the entire pressurizing chamber body 10a and then flows toward the first individual flow path 12, so that the liquid is less likely to stagnate in the pressurizing chamber body 10a.

[0045] The second individual flow passage 14 is drawn out in a planar direction from the surface of the descender 10b on the discharge hole surface 4-2 side and connected to the second common flow passage 24. The drawing direction is the same as the direction in which the descender 10b is shifted relative to the pressurizing chamber main body 10a.

[0046] The angle between the first direction and the second direction (the longitudinal direction of the head body 2a) is shifted from a right angle. Therefore, the ejection holes 8 belonging to the ejection hole arrays 9A arranged along the first direction are shifted in the second direction by the angle shifted from the right angle. And, because the ejection hole arrays 9A are arranged side by side in the second direction, the ejection holes 8 belonging to different ejection hole arrays 9A are shifted in the second direction by that amount. Combined, the ejection holes 8 of the first flow path member 4 are arranged side by side at regular intervals in the second direction, which allows printing to fill a predetermined range with pixels formed by the ejected liquid.

[0047] If the ejection holes 8 belonging to one ejection hole row 9A are arranged in a completely straight line along the first direction, it is possible to print to fill the specified range as described above. However, when arranged in this manner, the misalignment between the direction perpendicular to the second direction and the transport direction that occurs when the liquid ejection head 2 is installed in the printer 1 has a large effect on printing accuracy. Therefore, it is preferable to swap the ejection holes 8 between adjacent ejection hole rows 9A from the above-mentioned straight line arrangement of the ejection holes 8.

[0048] In this embodiment, the discharge holes 8 are arranged as follows. In Fig. 3, when the discharge holes 8 are projected in a direction perpendicular to the second direction, 32 discharge holes 8 are projected within the range of an imaginary straight line R, and the discharge holes 8 are arranged at intervals of 360 dpi within the imaginary straight line R. As a result, if the print paper P is conveyed in a direction perpendicular to the imaginary straight line R and printed, it is possible to print at a resolution of 360 dpi. The discharge holes 8 projected within the imaginary straight line R are all (16 holes) of the discharge holes 8 belonging to one discharge hole row 9A and half (8 holes) of the discharge holes 8 belonging to each of the two discharge hole rows 9A located on both sides of the discharge hole row 9A. In each discharge hole row 9B, the discharge holes 8 are arranged at intervals of 22.5 dpi (because 360 / 16=22.5).

[0049] The first common flow path 20 and the second common flow path 24 are straight in the range where the ejection holes 8 are aligned in a straight line, and are offset in parallel between the ejection holes 8 where the straight lines are offset. In the first common flow path 20 and the second common flow path 24, there are few offset locations, so the flow path resistance is small. In addition, the parallel offset portions are arranged at positions that do not overlap with the pressurizing chambers 10, so that the variation in ejection characteristics for each pressurizing chamber 10 can be reduced.

[0050] The pressurizing chamber rows 11A at both ends in the second direction (i.e., two rows in total) include a normal pressurizing chamber 10 and a first dummy pressurizing chamber 10D (for this reason, the pressurizing chamber rows 11A are sometimes referred to as dummy pressurizing chamber rows 11D). Further outside the dummy pressurizing chamber rows 11D, a dummy pressurizing chamber row 11D (i.e., two rows in total at both ends) in which only the dummy pressurizing chambers 10D are arranged is disposed. The flow paths at both ends in the second direction (i.e., two in total) have the same shape as the normal first common flow path 24, but are not directly connected to the pressurizing chambers 10, and are only connected to the dummy pressurizing chambers 10D.

[0051] The first flow path member 4 has an end flow path 30 extending in the first direction at a position outside the common flow path group consisting of the first common flow path 20 and the second common flow path 24 in the second direction. The end flow path 30 is a flow path connecting an opening 30c arranged further outside the opening 20a of the first common flow path 20 arranged on the pressurizing chamber surface 4-1 and an opening 30d arranged further outside the opening 24a of the second common flow path 24 arranged on the pressurizing chamber surface 4-1, and the flow path resistance of the end flow path 30 is smaller than the flow path resistance of the first common flow path 20 and the second common flow path 24. The end flow path 30 will be described in detail later.

[0052] The second flow path member 6 is joined to the pressurizing chamber surface 4-1 of the first flow path member 4, and has a second unified flow path 26 that supplies liquid to the second common flow path 24, and a first unified flow path 22 that recovers liquid from the first common flow path 20. The second flow path member 6 is thicker than the first flow path member 4, and is about 5 to 30 mm thick.

[0053] The second flow path member 6 is joined to the pressure chamber surface 4-1 of the first flow path member 4 in an area where the piezoelectric actuator substrate 40 is not connected. More specifically, it is joined so as to surround the piezoelectric actuator substrate 40. In this manner, it is possible to prevent a part of the ejected liquid from adhering to the piezoelectric actuator substrate 40 as a mist. In addition, since the first flow path member 4 is fixed at the outer periphery, it is possible to prevent the first flow path member 4 from vibrating in response to the driving of the displacement element 50, thereby preventing resonance and the like from occurring.

[0054] A through hole 6c penetrates vertically at the center of the second flow path member 6. A wiring member such as an FPC (Flexible Printed Circuit) that transmits a drive signal for driving the piezoelectric actuator substrate 40 is passed through the through hole 6c. The first flow path member 4 side of the through hole 6c is a widened portion 6ca that is wider in the short side direction, and the wiring member extending from the piezoelectric actuator substrate 40 to both sides in the short side direction is bent at the widened portion 6ca and directed upwards before passing through the through hole 6. The convex portion of the portion that widens into the widened portion 6ca is preferably R-shaped since it may damage the wiring member.

[0055] By disposing the first unified flow path 22 in the second flow path member 6 that is separate from and thicker than the first flow path member 4, the cross-sectional area of ​​the first unified flow path 22 can be increased, thereby reducing the difference in pressure loss due to the difference in the position where the first unified flow path 22 and the first common flow path 20 are connected. It is preferable that the flow path resistance of the first unified flow path 22 (more precisely, the flow path resistance of the range of the first unified flow path 22 that is connected to the first common flow path 20) is 1 / 100 or less of that of the first common flow path 20.

[0056] By disposing the second integrated flow path 26 in the second flow path member 6 that is separate from and thicker than the first flow path member 4, the cross-sectional area of ​​the second integrated flow path 26 can be increased, thereby reducing the difference in pressure loss due to the difference in the position where the second integrated flow path 26 and the second common flow path 24 are connected. The flow path resistance of the second integrated flow path 26 (more precisely, the flow path resistance of the range of the second integrated flow path 26 that is connected to the first integrated flow path 22) is preferably set to 1 / 100 or less of the second common flow path 24.

[0057] The first unified flow path 22 is disposed at one end in the short side direction of the second flow path member 6, and the second unified flow path 26 is disposed at the other end in the short side direction of the second flow path member 6, with each flow path facing the first flow path member 4 side and connected to the first common flow path 20 and the second common flow path 24, respectively. In this manner, the cross-sectional areas of the first unified flow path 22 and the second unified flow path 26 can be increased (i.e., the flow path resistance can be reduced), the outer periphery of the first flow path member 4 is fixed by the second flow path member 6 to increase rigidity, and further a through hole 6c through which a wiring member passes can be provided.

[0058] The second flow path member 6 is configured by stacking second flow path member plates 6a and 6b. On the upper surface of the plate 6b, a groove that becomes the first integrated flow path main body 22a, which is a portion of the first integrated flow path 22 that extends in the second direction and has a low flow path resistance, and a groove that becomes the second integrated flow path main body 26a, which is a portion of the second integrated flow path 26 that extends in the second direction and has a low flow path resistance, are arranged.

[0059] A plurality of first connection flow paths 22b extend downward (toward the first flow path member 4) from the groove that becomes the first integrated flow path main body 22a, and are connected to the opening 20a of the first common flow path that opens on the pressurizing chamber surface 4-1. The first connection flow paths 22b are separated by partitions 6ba (i.e., the first common flow path 20 side of the first connection flow paths 22b is branched). This can increase the rigidity of the connection between the second flow path member 6 and the first flow path member 4. Furthermore, in the second direction, the length of the partition 6ba is longer than the length of the first connection flow path 22b, so that the rigidity of the connection between the second flow path member 6 and the first flow path member 4 can be increased.

[0060] A plurality of second connection flow paths 26b extend downward (toward the first flow path member 4) from the groove that becomes the second integrated flow path main body 26a, and are connected to the opening 24a of the second common flow path that opens on the pressurizing chamber surface 4-1. The second connection flow paths 26b are separated by partitions 6bb (that is, the second common flow path 24 side of the second connection flow paths 26b is branched). This can increase the rigidity of the connection between the second flow path member 6 and the first flow path member 4. Furthermore, in the second direction, the length of the partition 6bb is longer than the length of the second connection flow paths 26b, so that the rigidity of the connection between the second flow path member 6 and the first flow path member 4 can be increased.

[0061] The plate 6a is provided with an opening 22c at one end in the second direction of the first integrated channel 22. The plate 6a is provided with an opening 26c at the other end in the second direction of the second integrated channel 26. The liquid is supplied from the opening 26c of the second integrated channel 26 and recovered from the opening 22c of the first integrated channel 22, although the supply and recovery may be reversed.

[0062] The first integrated flow path 22 and the second integrated flow path 26 may be provided with dampers to stabilize the supply or discharge of liquid against fluctuations in the discharge amount of liquid. In addition, a filter may be provided in the first integrated flow path 22 and the second integrated flow path 26 to prevent foreign matter and air bubbles from entering the first flow path member 4.

[0063] A piezoelectric actuator substrate 40 including the displacement elements 50 is bonded to the pressure chamber surface 4-1, which is the upper surface of the first flow path member 4, and each displacement element 50 is arranged so as to be located above the pressure chamber 10. The piezoelectric actuator substrate 40 occupies an area having substantially the same shape as the pressure chamber group formed by the pressure chambers 10. The opening of each pressure chamber 10 is closed by bonding the piezoelectric actuator substrate 40 to the pressure chamber surface 4-1 of the flow path member 4. The piezoelectric actuator substrate 40 has a rectangular shape that is long in the same direction as the head body 2a. A signal transmission unit such as an FPC for supplying a signal to each displacement element 50 is connected to the piezoelectric actuator substrate 40. The second flow path member 6 has a through hole 6c that penetrates vertically at the center, and the signal transmission unit is electrically connected to the control unit 88 through the through hole 6c. It is preferable to form the signal transmission section in a shape that extends in the short direction from one long side end of the piezoelectric actuator substrate 40 to the other long side end, and to have the wiring arranged in the signal transmission section extend along the short side direction and be aligned in the long direction, as this makes it easier to maintain a distance between the wiring.

[0064] Individual electrodes 44 are disposed on the upper surface of the piezoelectric actuator substrate 40 at positions facing the pressure chambers 10, respectively.

[0065] The flow path member 4 has a laminated structure in which a plurality of plates are laminated. Twelve plates, from plate 4a to plate 4l, are laminated in order from the pressurizing chamber surface 4-1 side of the flow path member 4. A large number of holes and grooves are formed in these plates. The holes and grooves can be formed, for example, by making each plate out of metal and etching it. The thickness of each plate is 10 to 300 μm. By setting the distance between the plates 4f-i to about m, the precision of the holes can be increased. The plates 4f-i are plates of the same shape, and may be formed from a single plate, but in order to form the holes with precision, the plates are formed from four plates. The plates are aligned and stacked so that the holes communicate with each other to form flow paths such as the first common flow path 20.

[0066] A pressure chamber body 10a is opened on the pressure chamber surface 4-1 of the flat flow path member 4, and a piezoelectric actuator substrate 40 is joined to the pressure chamber body 10a. The pressure chamber surface 4-1 also has an opening 24a for supplying liquid to the second common flow path 24 and an opening 20a for recovering liquid from the first common flow path 20. An ejection hole 8 is opened on the ejection hole surface 4-2, which is the surface of the flow path member 4 opposite to the pressure chamber surface 4-1. A plate may be further laminated on the pressure chamber surface 4-1 to close the opening of the pressure chamber body 10a, and the piezoelectric actuator substrate 40 may be joined on top of the plate. In this way, the possibility that the ejected liquid will come into contact with the piezoelectric actuator substrate 40 can be reduced, and reliability can be improved.

[0067] The structure for discharging liquid includes a pressure chamber 10 and a discharge hole 8. The pressure chamber 10 is made up of a pressure chamber main body 10a facing the displacement element 50, and a descender 10b having a smaller cross-sectional area than the pressure chamber main body 10a. The pressure chamber main body 10a is formed in the plate 4a, and the descender 10b is made up of holes formed in the plates 4b to k that are overlapped and further blocked (except for the discharge hole 8) by the nozzle plate 4l.

[0068] A first individual flow path 12 is connected to the pressurizing chamber main body 10a, and the first individual flow path 12 is connected to a first common flow path 20. The first individual flow path 12 includes a circular hole penetrating the plate 4b, a through groove extending in the planar direction in the plate 4c, and a circular hole penetrating the plate 4d. The first common flow path 20 is formed by overlapping holes formed in the plates 4f to 4i, and is further blocked on the upper side by the plate 4e and on the lower side by the plate 4j.

[0069] The descender 10b is connected to a second individual flow path 14, which is connected to a second common flow path 24. The second individual flow path 14 is a through groove extending in a planar direction in the plate 4j. The second common flow path 24 is formed by overlapping holes formed in the plates 4f to 4i, and is further blocked on the upper side by the plate 4e and on the lower side by the plate 4j.

[0070] Regarding the flow of liquid, to summarize, the liquid supplied to the second integrated flow path 26 passes through the second common flow path 24 and the second individual flow paths 14 in this order, and enters the pressurized chamber 10, and a part of the liquid is ejected from the ejection hole 8. The liquid that is not ejected passes through the first individual flow paths 12, enters the first common flow path 20, and then enters the first integrated flow path 22, and is discharged to the outside of the head body 2.

[0071] The piezoelectric actuator substrate 40 has a laminated structure consisting of two piezoelectric ceramic layers 40a and 40b, which are piezoelectric bodies. Each of these piezoelectric ceramic layers 40a and 40b has a thickness of about 20 μm. That is, the thickness from the upper surface of the piezoelectric ceramic layer 40a of the piezoelectric actuator substrate 40 to the lower surface of the piezoelectric ceramic layer 40b is about 40 μm. The thickness ratio of the piezoelectric ceramic layer 40a to the piezoelectric ceramic layer 40b is 3:7 to 7:3, preferably 4:6 to 6:4. Both of the piezoelectric ceramic layers 40a and 40b extend so as to straddle the multiple pressure chambers 10. These piezoelectric ceramic layers 40a and 40b are made of, for example, lead zirconate titanate (PZT)-based, NaNbO3-based, BaTiO3-based, (BiNa)NbO3-based, BiNaNb5O-based, or other ferroelectric materials. 15 The ceramic material is made of ceramics such as SiO2.

[0072] The piezoelectric actuator substrate 40 has a common electrode 42 made of a metal material such as Ag-Pd, and individual electrodes 44 made of a metal material such as Au. The common electrode 42 has a thickness of about 2 μm, and the individual electrodes 44 have a thickness of about 1 μm.

[0073] The individual electrodes 44 are disposed at positions facing the respective pressure chambers 10 on the upper surface of the piezoelectric actuator substrate 40. The individual electrodes 44 include an individual electrode body 44a, the planar shape of which is slightly smaller than the pressure chamber body 10a and has a shape substantially similar to the pressure chamber body 10a, and an extraction electrode 44b that is extracted from the individual electrode body 44a. A connection electrode 46 is formed on one end of the extraction electrode 44b that is extracted to the outside of the region facing the pressure chamber 10. The connection electrode 46 is a conductive resin containing conductive particles such as silver particles, and is formed to a thickness of about 5 to 200 μm. The connection electrode 46 is electrically connected to an electrode provided in the signal transmission section.

[0074] In addition, a surface electrode for a common electrode (not shown) is formed on the upper surface of the piezoelectric actuator substrate 40. The surface electrode for a common electrode and the common electrode 42 are electrically connected via a through conductor (not shown) disposed in the piezoelectric ceramic layer 40a.

[0075] Although details will be described later, a drive signal is supplied from the control unit 88 through a signal transmission unit to the individual electrodes 44. The drive signal is supplied in a constant cycle in synchronization with the transport speed of the print medium P.

[0076] The common electrode 42 is formed over almost the entire surface in the plane direction in the region between the piezoelectric ceramic layers 40a and 40b. That is, the common electrode 42 extends so as to cover all the pressure chambers 10 in the region facing the piezoelectric actuator substrate 40. The common electrode 42 is connected to a surface electrode for a common electrode formed on the piezoelectric ceramic layer 40a at a position avoiding the electrode group consisting of the individual electrodes 44, through a via hole formed through the piezoelectric ceramic layer 40a, and is grounded and held at the ground potential. The surface electrode for a common electrode is connected directly or indirectly to the control unit 88, like the multiple individual electrodes 44.

[0077] The portion of the piezoelectric ceramic layer 40a sandwiched between the individual electrode 44 and the common electrode 42 is polarized in the thickness direction, and is a displacement element 50 with a unimorph structure that is displaced when a voltage is applied to the individual electrode 44. More specifically, when the individual electrode 44 is set to a potential different from that of the common electrode 42 and an electric field is applied to the piezoelectric ceramic layer 40a in the polarization direction, the portion to which the electric field is applied acts as an active portion that is distorted by the piezoelectric effect. In this configuration, when the control unit 88 sets the individual electrode 44 to a predetermined potential that is positive or negative with respect to the common electrode 42 so that the electric field and the polarization are in the same direction, the portion of the piezoelectric ceramic layer 40a sandwiched between the electrodes (active portion) contracts in the planar direction. On the other hand, the piezoelectric ceramic layer 40b, which is an inactive layer, is not affected by the electric field and does not contract spontaneously but tries to restrict the deformation of the active portion. As a result, a difference in strain in the polarization direction occurs between the piezoelectric ceramic layer 40a and the piezoelectric ceramic layer 40b, and the piezoelectric ceramic layer 40b deforms so as to be convex toward the pressure chamber 10 (unimorph deformation).

[0078] Next, the liquid ejection operation will be described. The displacement elements 50 are driven (displaced) by a drive signal supplied to the individual electrodes 44 via a driver IC or the like under the control of the control unit 88. In this embodiment, liquid can be ejected by various drive signals, but here, a so-called push-pull drive method will be described.

[0079] The individual electrodes 44 are set in advance to a higher potential than the common electrode 42 (hereinafter referred to as high potential), and each time an ejection request is made, the individual electrodes 44 are temporarily set to the same potential as the common electrode 42 (hereinafter referred to as low potential), and then at a predetermined timing are set to the high potential again. As a result, at the timing when the individual electrodes 44 become low potential, the piezoelectric ceramic layers 40a, 40b (start) returning to their original (flat) shape, and the volume of the pressure chamber 10 increases compared to the initial state (state in which the potentials of both electrodes are different). As a result, a negative pressure is applied to the liquid in the pressure chamber 10. Then, the liquid in the pressure chamber 10 starts to vibrate at its natural vibration period. Specifically, at first, the volume of the pressure chamber 10 starts to increase, , the negative pressure gradually decreases. Next, the volume of the pressurizing chamber 10 reaches a maximum and the pressure becomes nearly zero. Next, the volume of the pressurizing chamber 10 starts to decrease and the pressure increases. Thereafter, when the pressure reaches nearly a maximum, the individual electrode 44 is set to a high potential. Then, the vibrations applied first and second overlap, and a greater pressure is applied to the liquid. This pressure propagates through the descender and causes the liquid to be ejected from the ejection hole 8.

[0080] In other words, droplets can be ejected by supplying a pulse drive signal that uses a high potential as a reference and a low potential for a certain period of time to the individual electrodes 44. If the pulse width is AL (Acoustic Length), which is half the time of the natural vibration period of the liquid in the pressure chamber 10, then, in principle, the ejection speed of the liquid is The natural vibration period of the liquid in the pressure chamber 10 is greatly influenced by the physical properties of the liquid and the shape of the pressure chamber 10, but is also influenced by the physical properties of the piezoelectric actuator substrate 40 and the characteristics of the flow path connected to the pressure chamber 10.

[0081] In order to stabilize the liquid ejection characteristics, the head body 2a is controlled to maintain a constant temperature. Also, the lower the viscosity of the liquid, the more stable the ejection and circulation of the liquid, so the temperature is basically set to above room temperature. Therefore, although heating is basically performed, cooling may also be performed if the ambient temperature is high. The following describes the case where heating is performed relative to the ambient temperature, but the same applies when cooling.

[0082] To keep the temperature constant, a heater is provided in the liquid ejection head 2, or the liquid to be supplied is temperature-adjusted. In either case, when there is a difference between the ambient temperature and the target temperature, there is a lot of heat radiation from the ends of the head body 2a in the longitudinal direction (second direction), so the temperatures of the pressure chambers 10 located at the ends in the second direction and the ends in the fourth direction tend to be lower than the temperature of the liquid in the pressure chamber 10 located in the center in the second direction. If there is a difference in the temperature of the liquid in each pressure chamber 10 or in the temperature of the displacement element 50, this can cause a difference in the ejection characteristics of the droplets, which can result in a decrease in printing accuracy.

[0083] The details of this embodiment will be described with reference to Fig. 6(a). The pressure chamber arrangement region 11C is a region in which the pressure chambers 10 are arranged. More specifically, it is a region with the smallest area among the convex-shaped regions including all the pressure chambers 10 present in the head main body 2a. Fig. 6(a) shows a rough parallelogram region.

[0084] The first integrated flow path 22 includes a first extension portion 22g that is disposed in at least the range in the second direction where the pressurizing chambers 10 exist (i.e., the range of the pressurizing chamber arrangement region 11C) and is disposed further in the first direction than the pressurizing chamber arrangement region 11C. The first extension portion 22g extends in the second direction. An end of the first extension portion 22g in the second direction is connected to a first end portion 22h that is a part of the first integrated flow path 22. The first end portion 22h is disposed to extend in the second direction further than the pressurizing chamber arrangement region 11C.

[0085] The second integrated flow path 26 includes a second extension portion 26g that is disposed in the third direction (opposite to the first direction) from the pressurizing chamber arrangement region 11C at least in the range in which the pressurizing chambers 10 exist (i.e., the range of the pressurizing chamber arrangement region 11C) in the fourth direction (opposite to the second direction). The second extension portion 26g extends in the fourth direction. An end of the second extension portion 26g in the fourth direction is connected to a second end portion 26h that is a part of the second integrated flow path 26. The second end portion 26h is disposed so as to extend in the fourth direction from the pressurizing chamber arrangement region 11C.

[0086] When the liquid circulates in the flow path, the first flow path member 4 and the second flow path member 6 around the flow path are directly heated. In addition, the heat spreads from the heated parts to the surroundings by thermal conduction, and the entire head main body 2a is heated.

[0087] The ends of the head body 2a in the second direction and the ends of the head body 2a in the fourth direction have a large surface area due to the short sides of the head body 2a when viewed in a plane, so heat escapes easily and the temperature tends to be lower than in the center of the head body 2a in the second direction. In addition, the ends of the head body 2a in the second direction and the ends of the head body 2a in the fourth direction are often attached to a printer, and the temperature is also lowered by heat being transferred to the printer.

[0088] At the end of the head body 2a in the second direction, the first end 22h extends into the second flow path member 6, and the second flow path member 6 and the first flow path member 4 are joined below the first end 22h. Therefore, heat of the liquid flowing through the first end 22h is transferred from the second flow path member 6 to the first flow path member 4, so that the temperature of the first flow path member 4 can be made uniform.

[0089] In this embodiment, the second flow path member 6 below the first end 22h is solid and does not have any gaps for damping or the like. This increases the thermal conductivity, so the temperature of the first flow path member 4 can be made more uniform. Note that the solid here may include minute gaps, such as adhesive escape grooves, with a width of 1 mm or 500 μm or less and a depth of 500 μm or less. If the first flow path member 4 below the first end 22h is solid, the temperature of the first flow path member 4 can be made more uniform.

[0090] Furthermore, if the lower surface of the first end portion 22h is configured to be the upper surface (pressurizing chamber surface 4-1) of the first flow path member 4, the heat of the liquid flowing through the first end portion 22h is more easily transmitted by being directly transmitted from the second flow path member 6 to the first flow path member 4, thereby making it possible to more uniformize the temperature of the first flow path member 4. In this case, the first end portion 22h is formed in a groove-like structure that opens to the lower side of the second flow path member 6, and by joining the first flow path member 4 to the second flow path member 6, the groove is closed by the first flow path member 4 to form the tubular first end portion 22h.

[0091] In addition, the flow path of the first end 22h may be directed downward (towards the first flow path member 4), temporarily connected to a flow path provided in the first flow path member 4, and then connected again to a flow path in the second flow path member 6, and then connected to the outside via the opening 22c.

[0092] At the end of the head body 2a in the fourth direction, a second end 26h extends into the second flow path member 6, and the second flow path member 6 and the first flow path member 4 are joined below the second end 26h. Therefore, heat of the liquid flowing through the second end 26h is transferred from the second flow path member 6 to the first flow path member 4, so that the temperature of the first flow path member 4 can be made uniform.

[0093] In this embodiment, the second flow path member 6 below the second end portion 26h is solid. This increases the thermal conductivity, and the temperature of the first flow path member 4 can be made more uniform. If the first flow path member 4 below the second end portion 26h is solid, the temperature of the first flow path member 4 can be made more uniform.

[0094] Furthermore, if the lower surface of the second end portion 26h is configured to be the upper surface (pressurization chamber surface 4-1) of the first flow path member 4, the heat of the liquid flowing through the second end portion 26h is more easily transmitted by being directly transmitted from the second flow path member 6 to the first flow path member 4, thereby making it possible to make the temperature of the first flow path member 4 more uniform.

[0095] In addition, the flow path of the second end 26h may be temporarily connected to a flow path provided in the first flow path member 4, and then again connected to a flow path in the second flow path member 6, and then connected to the outside via the opening 26c.

[0096] The structure of the second flow path member 6 and the first flow path member 4 in the vicinity of the first end 22h and the second end 26h is such that the second flow path member 6 and the first flow path member 4 are not only located below the first end 22h and the second end 26h, but also located at least somewhere in the range in which the first end 22h and the second end are present in the second direction. Providing a solid portion across the short side is preferable for uniform temperature distribution.

[0097] The first end 22h not only extends in the second direction further than the pressure chamber arrangement region 11C, but also extends in the third direction, making it difficult for the influence from the end of the head body 2a in the second direction to be transmitted to the pressure chamber arrangement region 11C. Here, extending in the third direction means extending in the third direction rather than the first direction, and more specifically means that the angle with respect to the third direction is smaller than 90 degrees.

[0098] If the first end 22h extends in the third direction beyond the center of the pressure chamber arrangement region 11C, the influence from the end of the head body 2a in the second direction can be made less likely to be transmitted to the pressure chamber arrangement region 11C. Extending in the third direction beyond the center of the pressure chamber arrangement region 11C means that there is a portion located in the third direction beyond the center of the pressure chamber arrangement region 11C in the direction perpendicular to the second direction. Specifically, as shown in FIG. 6(b), it indicates that there is a portion of the first end 122h located in the third direction beyond the virtual straight line L1 indicating the center of the pressure chamber arrangement region 11C in the direction perpendicular to the second direction.

[0099] Similarly, for the second end 26h, if the second end 26h extends in the first direction further than the center of the pressure chamber arrangement region 11C, the influence from the end of the head body 2a in the fourth direction can be made less likely to be transmitted to the pressure chamber arrangement region 11C. Fig. 6(b) shows an embodiment in which the first end 126h has a portion located in the first direction further than the imaginary straight line L1 indicating the center of the pressure chamber arrangement region 11C in the direction perpendicular to the second direction.

[0100] 6(c), if the first end 222h extends further in the third direction than the pressure chamber arrangement region 11C, the influence from the end of the head body 2a in the second direction can be made less likely to be transmitted by the pressure chamber arrangement region 11C. Extending further in the third direction than the pressure chamber arrangement region 11C means that there is a portion of the pressure chamber arrangement region 11C that is located in the third direction further from the virtual straight line L2 that is the furthest away in the direction perpendicular to the second direction.

[0101] Similarly, as shown in Fig. 6(c), if the second end 226h extends in the first direction further than the pressure chamber arrangement region 11C, the influence from the end of the head body 2a in the fourth direction can be made less likely to be transmitted by the pressure chamber arrangement region 11C. Extending in the first direction further than the pressure chamber arrangement region 11C means that there is a portion of the pressure chamber arrangement region 11C that is located in the first direction further than the virtual straight line L3 that is the furthest away in the direction perpendicular to the second direction.

[0102] The second flow path member 6 has a rectangular shape, and the second direction is substantially parallel to the first two opposing sides of the rectangular shape. Here, substantially parallel means that the angle formed is 5 degrees or less. The first direction is inclined with respect to the second two opposing sides of the rectangular shape, which are different from the first two opposing sides. The inclination is toward the second direction. As a result, the pressurizing chamber 10 arranged at the end of the second direction is arranged in the fourth direction at the end of the third direction, rather than at the end of the first direction (see FIG. 3). This portion corresponds to a portion where there is no flow path between the first unified flow path 22 and the second unified flow path 26, even if the first end 22h extends in the third direction. That is, this portion is more susceptible to the influence of the temperature at the end of the head main body 2a in the second direction, and since this portion is recessed in the fourth direction, it can be made less susceptible to the influence of the temperature. Such an arrangement relationship is similar at the end of the fourth direction, so that even at the end of the fourth direction, it can be made less susceptible to the influence of the temperature.

[0103] The first extension portion 22g extends in the second direction along the pressure chamber arrangement region 11C. It is preferable that the first extension portion 22g extends over at least the side of the pressure chamber arrangement region 11C on the first direction side. This makes it possible to make the temperature of the pressure chamber arrangement region 11C more uniform. If the stagnation portion 22g extends in the fourth direction beyond the side of the first direction side of the pressure chamber arrangement region 11C, it is preferable because it is less susceptible to the temperature influence from the end of the head body 2a in the fourth direction. However, even if the stagnation portion extends in the fourth direction beyond the opening 20a of the first common flow path 20, the stagnation portion is out of the liquid circulation path, so the liquid is not exchanged very much and its contribution to temperature equalization is relatively small. In addition, the stagnation of the liquid may cause effects such as the pigment in the liquid being more likely to settle.

[0104] Therefore, an end flow path 30 is provided on the fourth direction side of the pressure chamber arrangement region 11C of the flow path member 4. The opening 30c of the end flow path 30 is arranged on the fourth direction side of the opening 20a of the first common flow path 20, so that the liquid flowing in the first extension portion 22g that extends in the fourth direction further than the opening 20a of the first common flow path 20 can be circulated through the end flow path 30.

[0105] The same can be done for the second extension portion 26g. That is, an end flow path 30 is provided on the second direction side of the pressure chamber arrangement region 11C of the flow path member 4. The opening 30d of the end flow path 30 is disposed on the second direction side of the opening 24a of the second common flow path 24, so that the liquid flowing in the second extension portion 26g extending in the second direction further than the opening 24a of the second common flow path 24 can be circulated through the end flow path 30.

[0106] Fig. 7(a) is a schematic plan view of a head body according to another embodiment of the present invention, showing the same portion as Fig. 6(a). Here, consider the distance along the second direction in the region where the first end 322h and the pressure chamber arrangement region 11C overlap in the second direction.

[0107] Distance D13 [mm] along the second direction on the third direction side of first end 322h is shorter than distance D11 [mm] along the second direction on the first direction side of first end 322h. As a result, the portion of the head main body that is easily affected by the temperature of the end in the second direction due to the discontinuity on the third direction side of first end 322h can be made less susceptible to the effects of temperature by the closer first end 322h.

[0108] A distance D21 [mm] along the second direction on the first direction side of the second end 326h is shorter than a distance D23 [mm] along the second direction on the third direction side of the second end 326h. This makes it possible for a portion of the head main body that is easily affected by the temperature of the end in the fourth direction due to the first direction side of the second end 326h being discontinued to be less susceptible to the temperature effects due to the closer second end 326h.

[0109] FIG. 7(b) is a schematic plan view of a head main body according to another embodiment of the present invention, showing the same portion as FIG. 6(a).

[0110] A distance D1 [mm] along the second direction between the first end 422h and the pressure chamber arrangement region 11C is shorter than a distance D2 [mm] along the second direction between the second end 426h and the pressure chamber arrangement region 11C. The liquid is supplied from the outside to the second unified flow path, passes through the first flow path member, and then passes through the first unified flow path to be recovered to the outside. Therefore, after passing through the second end 426h, the liquid with a lowered temperature passes through the first end 422h. Therefore, by adopting the above-mentioned arrangement, even if the temperature of the liquid passing through the first end 422h becomes slightly lower, the difference is unlikely to affect the pressure chamber arrangement region 11C.

[0111] The distance D1 [mm] along the second direction between the first end 422h and the pressure chamber arrangement region 11C is the average distance along the second direction between the first end 422h and the pressure chamber arrangement region 11C. More specifically, the distance D1 [mm] is the distance along the second direction in the region where the first end 422h and the pressure chamber arrangement region 11C overlap in the second direction. In FIG. 7(b), the distance D1 [mm] is the distance along the second direction on the third direction side of the first end 422h. This is the arithmetic mean of D13 [mm] and the distance D11 [mm] along the second direction on the first direction side of the first end 422h.

[0112] The distance D2 [mm] along the second direction between the second end 426h and the pressure chamber arrangement region 11C is the average distance along the second direction between the second end 426h and the pressure chamber arrangement region 11C. In Fig. 7(b), the distance D2 [mm] is the arithmetic mean of the distance D21 [mm] along the second direction on the first direction side of the second end 426h and the distance D23 [mm] along the second direction on the third direction side of the second end 426h.

[0113] FIG. 7(c) is a schematic plan view of a head main body according to another embodiment of the present invention, showing the same portion as FIG. 6(a).

[0114] The first end 522h has a smaller cross-sectional area on the downstream side of the opening to the outside than on the upstream side of the first extension portion. The second end 526h has a smaller cross-sectional area on the downstream side of the second extension portion than on the upstream side of the opening to the outside. Therefore, the average cross-sectional area of ​​the first end 522h is smaller than the average cross-sectional area of ​​the second end 526h. Since the liquid has a lower thermal conductivity than the second flow path member 6, the thick portion can reduce heat loss to the outside due to thermal conduction. This can suppress the temperature drop on the downstream side where the temperature drop is greater.

[0115] In the head body 2a, end flow paths 30 are provided on the outer side of the first flow path member 4 in the second direction and the outer side of the pressure chamber arrangement region 11C in the fourth direction. The end flow paths 30 have a lower flow path resistance than the common flow paths (the first common flow path 20 and the second common flow path). Since the flow path resistance of the end flow paths 30 is low, the flow rate per hour of the liquid flowing in the end flow paths 30 is higher than the flow rate per hour of the liquid flowing in the common flow paths. Therefore, even if the heat radiation from the end of the head body 2a in the second direction is large, the temperature is not easily transmitted across the end flow paths 30, so the temperature difference in the pressure chamber arrangement region 11C can be reduced. The flow path resistance of the common flow path is preferably at least twice, particularly at least three times, the flow path resistance of the end flow paths 30.

[0116] In addition, not only can the liquid flowing through the end flow paths 30 in the first flow path member 4 suppress a drop in temperature, but the presence of the end flow paths 30 makes it possible to arrange the first extension portion 22g to extend toward the fourth direction side so as to prevent liquid stagnation from occurring, and the second extension portion 26g to extend toward the second direction side so as to prevent liquid stagnation from occurring.

[0117] The flow path resistance of the common flow path refers to the flow path resistance from the opening 24b of one second common flow path 24 to the opening 20a of one first common flow path 20. In this embodiment, the liquid supplied to one second common flow path 24 flows into the pressure chambers of the two pressure chamber rows 11A, and further flows into the two first common flow paths 20. Conversely, the liquid from the two second common flow paths 24 flows into the one first common flow path 20. From this relationship, the flow path resistance of the common flow path is the same as the flow path resistance when the liquid supplied to one second common flow path 24 flows into the pressure chambers of the two pressure chamber rows 11A, and further flows into a flow path resistance twice that of the first common flow path 20. In other words, the flow resistance of the common flow path is the flow resistance of the second common flow path 24 + (flow resistance of individual flow paths / 16 + flow resistance of the first common flow path 24 x 2) / 2, which is the flow resistance of the first common flow path 20 + the flow resistance of the second common flow path 24 + the flow resistance of the individual flow paths / 32, which is the flow resistance of the first common flow path 20 + the flow resistance of the second common flow path 24 + the flow resistance of the two rows of pressure chambers 11A.

[0118] In this embodiment, the end flow paths 30 are provided on both sides of the pressure chamber arrangement region 11C, and while it is better to provide them on both sides in order to stabilize the temperature, the temperature can be stabilized on only one side.

[0119] When the head body 2a is fixed to the printer 1 at the end of the head body 2a in the second direction, the thermal conduction from both ends of the head body 2a to the printer 1 becomes large, so there is a high need to provide an end flow path 30 in such a head body 2a.

[0120] The end flow passage 30 is provided with a wide portion 30a whose width is wider than the width of the common flow passage, and a third damper 28c is provided on the pressurizing chamber side 4-1 of the wide portion 30a. The third damper 28C is deformable with one surface facing the wide portion 30a and the other surface facing the damper chamber 29. The damping capacity of the damper is largely influenced by the narrowest part across the deformable area. Since the size of the head body 2a that widens the width of the common flow passage becomes large, the width of the common flow passage cannot be made too large, and there is a risk that the damping capacity is insufficient with only the first damper 28A and the second damper 28B provided in the common flow passage. By increasing the width of the wide portion 30a, the damping capacity of the third damper 28C can be increased. It is preferable that the width of the wide portion 30a is at least twice, particularly at least three times, the width of the common flow passage.

[0121] A damper may also be provided on the discharge hole surface 4-2 side of the wide portion 30a to further increase the damping capacity.

[0122] In the above embodiment, the first common flow path 20 is not directly connected to the second unified flow path 26, and the second common flow path 24 is not directly connected to the first unified flow path 22, but the present invention is not limited to such an embodiment. That is, the common flow path may directly connect the first unified flow path 22 and the second unified flow path 26.

[0123] In addition, in the above embodiment, the liquid is allowed to circulate throughout the printer 1 by passing through the head main body 2a, but the printer may also be used without circulation by supplying liquid from both the first integrated flow path 22 and the second integrated flow path 26.

[0124] Also, the first unified flow path 22 and the second unified flow path 26 may be disposed in the first flow path member 4, not in the second flow path member 6. In this way, the first unified flow path 22, the second unified flow path 26, the first common flow path 20, and the second common flow path 24 can be disposed in the same plane in the first flow path member 4, and the temperature in the planar direction can be more uniform. However, if the first unified flow path 22 and the second unified flow path 26 are to be flowed with an amount of liquid to be printed and an amount of liquid to suppress retention and enable temperature control, it is necessary to increase the thickness of the first flow path member 4 to increase the height of the cross section of the first unified flow path 22 and the second unified flow path 26, or to increase the size of the head main body 2a in the short side direction to increase the width of the cross section of the first unified flow path 22 and the second unified flow path 26. In the former case, it may be difficult to increase the driving frequency due to the longer AL, and in the latter case, the head main body 2a becomes larger, and when multiple head main bodies 2a are used, the spacing between them becomes wider, which may result in lower printing accuracy. Therefore, it is preferable to arrange the first unified flow path 22 and the second unified flow path 26 in the second flow path member 6. [Explanation of symbols]

[0125] 1. Printer 2. Liquid ejection head 2a Head body 4...First flow path member 4a to 4l (first flow path member) plates 4-1 Pressurized chamber surface 4-2...Discharge hole surface 6...Second flow path member 6a, 6b... (second flow path member) plates 6ba, 6bb... Partition 6c...(Second flow path member) through hole 6ca... Widened portion of through hole 8...Discharge hole 9A...Discharge hole row 9B...Discharge hole row 10. Pressurizing chamber 10a Pressurizing chamber body 10b Partial flow path (descender) 10D... Dummy pressure chamber 11A Pressurized chamber row 11B... Pressurized chamber line 11C: Pressure chamber arrangement area 12...First individual flow path 14...Second individual flow path 20...First common flow path (common flow path) 20a (first common flow path) opening 22...First integrated channel 22a...First integrated flow path body 22b...First connecting flow path 22c (first integrated channel) opening 22g...1st extension part 22h...1st end 24...Second common flow path (common flow path) 24a (Opening of second common flow path) 26...Second integrated channel 26a...Second integrated flow path body 26b...Second connecting flow path 26c (Opening of second integrated channel) 26g...Second extension part 26h...2nd end 28A···First damper 28B Second damper 28C···Third damper 29. Damper chamber 30 End passage 30a Wide section 30b...Stenosis 30c, 30d... (end flow passage) opening 40 Piezoelectric actuator substrate 40a Piezoelectric ceramic layer 40b Piezoelectric ceramic layer (diaphragm) 42...Common electrode 44...Individual electrode 44a... Individual electrode body 44b...Extraction electrode 46 Connection electrode 50... Displacement element (pressure section) 60 Signal transmission section 70···(head mounted) frame 72 Head group 80A···Feed roller 80B Collection roller 82A Guide roller 82B: Transport roller 88...Control section P...Printing paper

Claims

1. a first flow path member having a plurality of discharge holes, a plurality of pressure chambers respectively connected to the plurality of discharge holes, and a plurality of common flow paths connected to the plurality of pressure chambers; a second flow path member having a first unified flow path that recovers liquid from the plurality of common flow paths and a second unified flow path that supplies liquid to the plurality of common flow paths; A plurality of pressurizing units for pressurizing the plurality of pressurizing chambers, respectively; Equipped with the second flow path member is located on the first flow path member, When viewed in plan view, The plurality of pressure chambers are arranged in a pressure chamber arrangement area, an outer edge of the pressure chamber arrangement area includes a first long edge and a second long edge facing each other, and a first short edge and a second short edge connecting an end of the first long edge and an end of the second long edge to each other, When a line connecting the center of the first short edge and the center of the second short edge is defined as a first center line, and a line connecting the center of the first long edge and the center of the second long edge is defined as a second center line, The second flow path member is a first opening located on the first long edge side with respect to the first center line and on the first short edge side with respect to the second center line; a second opening located on the second long edge side with respect to the first center line and on the second short edge side with respect to the second center line; It has The first opening is connected to the first integrated flow path, The second opening is connected to the second integrated flow path, the first integrated flow passage extends from the first opening to the second long edge side with respect to the first center line and from the first opening to the second short edge side with respect to the second center line; The second joint flow passage extends from the second opening to the first long edge side with respect to the first center line and from the second opening to the first short edge side with respect to the second center line. Liquid ejection head.

2. The first integrated flow path is a first flow path extending in a direction along the first long edge and the second long edge; a second flow path extending in a direction intersecting the first flow path; Contains The angle between the first flow path and the second flow path is greater than 90 degrees. The liquid ejection head according to claim 1 .

3. The second flow path is connected to the first opening, The first flow path is connected to the second flow path. The liquid ejection head according to claim 2 .

4. The second integrated flow path is a third flow path extending in a direction along the first long edge and the second long edge; a fourth flow path extending in a direction intersecting the third flow path; Contains The angle between the third flow path and the fourth flow path is greater than 90 degrees.

4. The liquid ejection head according to claim 1.

5. The fourth flow path is connected to the second opening, The third flow path is connected to the fourth flow path.

5. The liquid ejection head according to claim 4.

6. The center of gravity of the first opening is located on the second long edge side with respect to the first long edge.

6. The liquid ejection head according to claim 1.

7. The center of gravity of the second opening is located on the first long edge side with respect to the second long edge.

7. The liquid ejection head according to claim 1.

8. The plurality of common flow paths include a common flow path located on the first short edge side with respect to the second center line and a common flow path located on the second short edge side with respect to the second center line. The liquid ejection head according to any one of claims 1 to 7.

9. The first flow path member is composed of a plurality of plates, The uppermost plate among the plurality of plates in which the pressure chambers are provided is located above the lowermost plate among the plurality of plates in which the common flow path is provided.

9. The liquid ejection head according to claim 1.

10. The pressurizing chamber includes a pressurizing chamber body and a descender that is connected from the pressurizing chamber body to the discharge hole, The pressure chamber body is located above the lower surface of the common flow channel. The liquid ejection head according to any one of claims 1 to 9.

11. The pressurizing chamber includes a pressurizing chamber body and a descender that is connected from the pressurizing chamber body to the discharge hole, The side wall of the pressure chamber body and the side wall of the descender are disposed so as to be in contact with each other. The liquid ejection head according to any one of claims 1 to 10.

12. The second flow path member is thicker than the first flow path member. The liquid ejection head according to any one of claims 1 to 11.

13. The area of ​​the first opening is larger than the area of ​​the second opening. The liquid ejection head according to any one of claims 1 to 12.

14. A recording apparatus comprising: a liquid ejection head according to any one of claims 1 to 13; a transport unit that transports a recording medium to said liquid ejection head; and a control unit that controls said liquid ejection head. Device.

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