JP2018047648A - Liquid discharge head, and recorder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid discharge head for preventing deterioration in discharge characteristics due to vibration of an inner wall of a compression chamber.SOLUTION: A liquid discharge head 2 comprises a first flow passage member and a piezoelectric actuator substrate. The piezoelectric actuator substrate blocks up an opening 10h of a plurality of compression chambers 10 of the first flow passage member. The piezoelectric actuator substrate also comprises: a common electrode overlapping with the first flow passage member side with respect to a piezoelectric ceramic layer and having an extent over a plurality of openings 10h; and a plurality of individual electrodes 44 overlapping with the opposite side of the first flow passage member with respect to the piezoelectric ceramic layer. The individual electrodes 44 comprise an individual electrode body 44a overlapping with the opening 10h in a plane perspective view and a lead-out electrode 44b connected to the individual electrode body 44a and positioned on the outside of the opening 10h. The first flow passage member comprises an expansion chamber 25 having an opening 25h projecting from the opening 10h and overlapping with the lead-out electrode 44b, in a plane perspective view.SELECTED DRAWING: Figure 7

Description

  The present disclosure relates to a liquid discharge head and a recording apparatus.

  Conventionally, as a print head, for example, a liquid discharge head that performs various types of printing by discharging a liquid onto a recording medium is known. The liquid discharge head includes, for example, a flow path member and a piezoelectric actuator substrate. The flow path member includes, for example, a plurality of discharge holes and a plurality of pressurizing chambers that are respectively connected to the plurality of discharge holes and open on the opposite side to the direction in which the plurality of discharge holes open to the outside. The piezoelectric actuator substrate is stacked on the flow path member so as to close the openings of the plurality of pressurizing chambers, and individually applies pressure to the plurality of pressurizing chambers. Thereby, the liquid is discharged from the discharge hole. The piezoelectric actuator substrate includes, for example, a piezoelectric layer having a width extending over a plurality of pressurizing chambers, a common electrode having a width extending over the plurality of pressurizing chambers and overlapping with the flow path member side of the piezoelectric layer. The body layer includes a plurality of individual electrodes that overlap with the channel member on the opposite side and are provided corresponding to the plurality of pressurizing chambers. The plurality of individual electrodes include an individual electrode main body that overlaps the pressurizing chamber and a lead electrode that is led out from the individual electrode main body and positioned outside the pressurizing chamber in plan perspective. In patent document 1, the space | gap part isolate | separated from the pressurization chamber is provided in the position which overlaps with an extraction electrode in planar perspective among the flow-path members.

JP 2014-231183 A

  A liquid discharge head according to an aspect of the present disclosure includes a flow path member and a piezoelectric actuator substrate. The flow path member has a plurality of discharge holes that open to the discharge side and a plurality of pressurization chamber openings that open to the opposite side of the discharge side. A plurality of pressurizing chambers are connected to each other. The piezoelectric actuator substrate overlaps the opposite side of the flow path member from the discharge side, and closes the plurality of pressurizing chamber openings. The piezoelectric actuator substrate overlaps the flow path member side with respect to the piezoelectric layer and a piezoelectric layer having a plurality of areas extending over the pressurizing chambers. A common electrode having a width over the pressure chamber opening and the piezoelectric layer on the opposite side of the flow path member, and each overlapping with the plurality of pressure chamber openings in a plan view. A plurality of individual electrodes. The individual electrode includes, in a plan view, an individual electrode body that overlaps the pressurization chamber opening, and an extraction electrode that is connected to the individual electrode body and is located outside the pressurization chamber opening. I have. The flow path member further includes an expansion chamber that opens to the piezoelectric actuator substrate side and has an expansion chamber opening that protrudes from the pressurization chamber opening and overlaps the extraction electrode in a plan view.

  A recording apparatus according to an aspect of the present disclosure includes the above-described liquid discharge head, a transport unit that transports a recording medium to the liquid discharge head, and a control unit that controls the liquid discharge head.

(A) is a side view schematically showing a recording apparatus including a liquid ejection head according to the first embodiment, and (b) is a plan view schematically showing a recording apparatus including a liquid ejection head according to the first embodiment. FIG. FIG. 3 is an exploded perspective view of the liquid ejection head according to the first embodiment. FIG. 3A is a perspective view of the liquid discharge head of FIG. 2, and FIG. 3B is a cross-sectional view of the liquid discharge head of FIG. (A) is a disassembled perspective view of a head main body, (b) is a perspective view seen from the lower surface of the 2nd flow path member. (A) is a plan view of the head body seen through a part of the second flow path member, and (b) is a plan view of the head body seen through the second flow path member. It is a top view which expands and shows a part of FIG. (A) is a perspective view of a discharge unit, (b) is a plan view of the discharge unit, and (c) is a plan view showing electrodes on the discharge unit. (A) is the VIIIa-VIIIa sectional view taken on the line of FIG.7 (b), (b) is the VIIIb-VIIIb sectional view taken on the line of FIG.7 (b). It is a conceptual diagram which shows the flow of the fluid inside a liquid discharge unit. It is the XX sectional view taken on the line of FIG.7 (c).

  Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. Note that the drawings used in the following description are schematic, and the dimensional ratios and the like on the drawings do not necessarily match the actual ones. Even in a plurality of drawings showing the same member, dimensional ratios and the like may not coincide with each other in order to exaggerate the shape and the like.

<First Embodiment>
(Entire printer configuration)
A color ink jet printer 1 (hereinafter referred to as a printer 1) including a liquid ejection head 2 according to the first embodiment will be described with reference to FIG.

  The printer 1 moves the recording medium P relative to the liquid ejection head 2 by conveying the recording medium P from the conveying roller 74 a to the conveying roller 74 b. The control unit 76 controls the liquid ejection head 2 based on image and character data, ejects the liquid toward the recording medium P, causes droplets to land on the recording medium P, and prints on the recording medium P. To do.

  In the present embodiment, the liquid discharge head 2 is fixed to the printer 1, and the printer 1 is a so-called line printer. Another embodiment of the recording apparatus is a so-called serial printer.

  A flat head mounting frame 70 is fixed to the printer 1 so as to be substantially parallel to the recording medium P. The head mounting frame 70 is provided with 20 holes (not shown), and the 20 liquid discharge heads 2 are mounted in the respective holes. The five liquid ejection heads 2 constitute one head group 72, and the printer 1 has four head groups 72.

  The liquid discharge head 2 has an elongated shape as shown in FIG. Within one head group 72, the three liquid ejection heads 2 are arranged along the direction intersecting the conveyance direction of the recording medium P, and the other two liquid ejection heads 2 are displaced along the conveyance direction. Thus, one each is arranged between the three liquid ejection heads 2. Adjacent liquid ejection heads 2 are arranged such that a range that can be printed by each liquid ejection head 2 is connected in the width direction of the recording medium P, or overlapped at the ends, and in the width direction of the recording medium P. Printing without gaps is possible.

  The four head groups 72 are arranged along the conveyance direction of the recording medium P. Each liquid discharge head 2 is supplied with ink from a liquid tank (not shown). The liquid discharge heads 2 belonging to one head group 72 are supplied with the same color ink, and the four head groups print four color inks. The colors of ink ejected from each head group 72 are, for example, magenta (M), yellow (Y), cyan (C), and black (K).

  Note that the number of liquid ejection heads 2 mounted on the printer 1 may be one if it is a single color and the range that can be printed by one liquid ejection head 2 is printed. The number of the liquid ejection heads 2 included in the head group 72 or the number of the head groups 72 can be appropriately changed depending on the printing target and printing conditions. For example, the number of head groups 72 may be increased in order to perform multicolor printing. In addition, by arranging a plurality of head groups 72 that print in the same color and alternately printing in the transport direction, the printing speed, that is, the transport speed can be increased. Alternatively, a plurality of head groups 72 for printing in the same color may be prepared and arranged so as to be shifted in the direction intersecting the transport direction to increase the resolution in the width direction of the recording medium P.

  In addition to printing colored ink, a liquid such as a coating agent may be printed for surface treatment of the recording medium P.

  The printer 1 performs printing on the recording medium P. The recording medium P is wound around the transport roller 74 a and passes between the two transport rollers 74 c and then passes below the liquid ejection head 2 mounted on the head mounting frame 70. Thereafter, it passes between the two transport rollers 74d and is finally collected by the transport roller 74b.

  The recording medium P may be cloth or the like in addition to printing paper. In addition, the printer 1 is configured to convey a conveyance belt instead of the recording medium P, and the recording medium is not only a roll-shaped one, but also a sheet, cut cloth, wood, Or a tile etc. may be sufficient. Furthermore, a wiring pattern of an electronic device may be printed by discharging a liquid containing conductive particles from the liquid discharge head 2. Furthermore, the chemical may be produced by discharging a predetermined amount of liquid chemical agent or a liquid containing the chemical agent from the liquid discharge head 2 toward the reaction container or the like to cause a reaction.

  Further, a position sensor, a speed sensor, a temperature sensor, or the like may be attached to the printer 1, and the control unit 76 may control each unit of the printer 1 according to the state of each unit of the printer 1 that can be understood from information from each sensor. In particular, if the discharge characteristics (discharge amount, discharge speed, etc.) of the liquid discharged from the liquid discharge head 2 are affected by the outside, the temperature of the liquid discharge head 2, the temperature of the liquid in the liquid tank, the liquid tank Depending on the pressure applied by the liquid to the liquid ejection head 2, the drive signal for ejecting the liquid in the liquid ejection head 2 may be changed.

(Overall configuration of liquid discharge head)
Next, the liquid ejection head 2 according to the first embodiment will be described with reference to FIGS. 5 and 6, in order to make the drawings easier to understand, the flow path and the like that should be drawn with a broken line below other members are drawn with a solid line. 5A shows a part of the second flow path member 6 in a transparent manner, and FIG. 5B shows the whole part of the second flow path member 6 in a transparent manner. In FIG. 9, the conventional liquid flow is indicated by a broken line, the liquid flow of the discharge unit 15 is indicated by a solid line, and the liquid flow supplied from the second individual flow path 14 is indicated by a long broken line.

  In the drawing, a first direction D1, a second direction D2, a third direction D3, a fourth direction D4, a fifth direction D5, and a sixth direction D6 are illustrated. The first direction D1 is one side in the direction in which the first common flow path 20 and the second common flow path 24 extend, and the fourth direction D4 is the direction in which the first common flow path 20 and the second common flow path 24 extend. On the other side. The second direction D2 is one side in the direction in which the first integrated flow path 22 and the second integrated flow path 26 extend, and the fifth direction D5 is the direction in which the first integrated flow path 22 and the second integrated flow path 26 extend. On the other side. The third direction D3 is one side of the direction orthogonal to the extending direction of the first integrated flow path 22 and the second integrated flow path 26, and the sixth direction D6 is the first integrated flow path 22 and the second integrated flow path. This is the other side of the direction orthogonal to the direction in which 26 extends.

  As shown in FIGS. 2 and 3, the liquid ejection head 2 includes a head body 2 a, a housing 50, a heat sink 52, a wiring board 54, a pressing member 56, an elastic member 58, and a signal transmission unit 60. And a driver IC 62. The liquid ejection head 2 only needs to include the head body 2a, and the housing 50, the heat radiating plate 52, the wiring board 54, the pressing member 56, the elastic member 58, the signal transmission unit 60, and the driver IC 62 are not necessarily provided. It does not have to be.

  In the liquid ejection head 2, the signal transmission unit 60 is drawn from the head body 2 a, and the signal transmission unit 60 is electrically connected to the wiring board 54. The signal transmission unit 60 is provided with a driver IC 62 that controls the driving of the liquid ejection head 2. The driver IC 62 is pressed against the heat radiating plate 52 by the pressing member 56 via the elastic member 58. In addition, illustration of the supporting member which supports the wiring board 54 is abbreviate | omitted.

  The heat radiating plate 52 can be formed of metal or alloy, and is provided to radiate the heat of the driver IC 62 to the outside. The heat radiating plate 52 is joined to the housing 50 by screws or an adhesive.

  The casing 50 is placed on the upper surface of the head main body 2 a, and the casing 50 and the heat radiating plate 52 cover each member constituting the liquid ejection head 2. The housing 50 includes a first opening 50a, a second opening 50b, a third opening 50c, and a heat insulating portion 50d. The first openings 50a are provided so as to face the third direction D3 and the sixth direction D6, respectively. By disposing the heat sink 52 in the first opening 50a, the first opening 50a is sealed. The second opening 50b opens downward, and the wiring board 54 and the pressing member 56 are disposed inside the housing 50 via the second opening 50b. The third opening 50c opens upward, and accommodates a connector (not shown) provided on the wiring board 54.

  The heat insulating portion 50d is provided so as to extend from the second direction D2 to the fifth direction D5, and is disposed between the heat dissipation plate 52 and the head body 2a. Thereby, the possibility that the heat radiated to the heat radiating plate 52 is transmitted to the head main body 2a can be reduced. The housing 50 can be formed of a metal, an alloy, or a resin.

  As shown in FIG. 4A, the head main body 2a has a long plate shape from the second direction D2 to the fifth direction D5, and includes a first flow path member 4, a second flow path member 6, and the like. And a piezoelectric actuator substrate 40. The head body 2 a is provided with a piezoelectric actuator substrate 40 and a second flow path member 6 on the upper surface of the first flow path member 4. The piezoelectric actuator substrate 40 is placed in a broken line area shown in FIG. The piezoelectric actuator substrate 40 is provided to pressurize a plurality of pressurizing chambers 10 (see FIG. 8) provided in the first flow path member 4, and has a plurality of displacement elements 48 (see FIG. 8). ing.

(Overall configuration of flow path member)
The first flow path member 4 has a plurality of flow paths formed therein, and guides the liquid supplied from the second flow path member 6 to the discharge holes 8 (see FIG. 8) provided on the lower surface. . The upper surface of the first flow path member 4 is a pressurizing chamber surface 4-1, and openings 20a, 24a, 28c, and 28d are formed in the pressurizing chamber surface 4-1. A plurality of openings 20a are provided and arranged along the second direction D2 to the fifth direction D5. The opening 20a is disposed at the end of the pressurizing chamber surface 4-1 in the third direction D3. A plurality of openings 24a are provided and are arranged along the second direction D2 to the fifth direction D5. The opening 24a is disposed at the end of the pressurizing chamber surface 4-1 in the sixth direction D6. The opening 28c is provided outside the opening 20a in the second direction D2 and outside in the fifth direction D5. The opening 28d is provided outside the opening 24a in the second direction D2 and outside in the fifth direction D5.

  The second flow path member 6 has a plurality of flow paths formed therein, and guides the liquid supplied from the liquid tank to the first flow path member 4. The second flow path member 6 is provided on the outer peripheral portion of the pressurizing chamber surface 4-1 of the first flow path member 4, and has an adhesive (not shown) outside the mounting area of the piezoelectric actuator substrate 40. ) To the first flow path member 4.

(Second channel member (integrated channel))
As shown in FIGS. 4 and 5, the second flow path member 6 has a through hole 6 a and openings 6 b, 6 c, 6 d, 22 a, and 26 a. The through hole 6 a is formed so as to extend from the second direction D 2 to the fifth direction D 5, and is disposed outside the mounting area of the piezoelectric actuator substrate 40. The signal transmission unit 60 is inserted through the through hole 6a.

  The opening 6b is provided on the upper surface of the second flow path member 6, and is disposed at the end of the second flow path member in the second direction D2. The opening 6 b supplies liquid from the liquid tank to the second flow path member 6. The opening 6c is provided on the upper surface of the second flow path member 6, and is disposed at the end of the second flow path member in the fifth direction D5. The opening 6c collects the liquid from the second flow path member 6 to the liquid tank. The opening 6d is provided on the lower surface of the second flow path member 6, and the piezoelectric actuator substrate 40 is disposed in the space formed by the opening 6d.

  The opening 22a is provided on the lower surface of the second flow path member 6, and is provided so as to extend from the second direction D2 toward the fifth direction D5. The opening 22a is formed at the end of the second flow path member 6 in the third direction D3, and is provided closer to the third direction D3 than the through hole 6a.

  The opening 22 a communicates with the opening 6 b, and the first integrated flow path 22 is formed by sealing the opening 22 a with the first flow path member 4. The first integrated flow path 22 is formed so as to extend from the second direction D2 to the fifth direction D5, and supplies liquid to the opening 20a and the opening 28c of the first flow path member 4.

  The opening 26a is provided on the lower surface of the second flow path member 6, and is provided so as to extend from the second direction D2 toward the fifth direction D5. The opening 26a is formed at the end of the second flow path member 6 in the sixth direction D6, and is provided on the sixth direction D6 side with respect to the through hole 6a.

  The opening 26 a communicates with the opening 6 c, and the second integrated flow path 26 is formed by sealing the opening 26 a with the first flow path member 4. The second integrated flow path 26 is formed to extend from the second direction D2 to the fifth direction D5, and collects liquid from the opening 24a and the opening 28d of the first flow path member 4.

  With the above configuration, the liquid supplied from the liquid tank to the opening 6b is supplied to the first integrated flow path 22, flows into the first common flow path 20 through the opening 22a, and the liquid flows into the first flow path member 4. Supplied. And the liquid collect | recovered by the 2nd common flow path 24 flows into the 2nd integrated flow path 26 via the opening 26a, and a liquid is collect | recovered outside via the opening 6c. Note that the second flow path member 6 is not necessarily provided.

  The liquid supply and recovery may be realized by appropriate means. For example, as shown by a dotted line in FIG. 3A, the printer 1 includes a first integrated flow path 22, a flow path of the first flow path member 4, a circulation flow path 78 including the second integrated flow path 26, A flow forming portion 79 that forms a flow from the first integrated flow path 22 to the second integrated flow path 26 via the flow path of the first flow path member 4 may be included.

  The configuration of the flow forming unit 79 may be appropriate. For example, the flow forming unit 79 includes a pump and performs suction from the opening 6c and / or discharge from the opening 6b. In addition, for example, the flow forming unit 79 includes a recovery space for storing the liquid recovered from the opening 6c, a supply space for storing the liquid supplied to the opening 6b, and a pump for sending the liquid from the recovery space to the supply space. And a pressure difference is generated between the first integrated flow path 22 and the second integrated flow path 26 by making the liquid level of the supply space higher than the liquid level of the recovery space. Good.

  A portion of the circulation channel 78 located outside the first channel member 4 and the second channel member 6 and the flow forming unit 79 may be a part of the liquid ejection head 2 or the liquid ejection head. 2 may be provided outside.

(First flow path member (common flow path and discharge unit))
As shown in FIGS. 5 to 8 and 10, the first flow path member 4 is formed by laminating a plurality of plates 4 a to 4 m, and is provided on the upper side when the cross section is viewed in the laminating direction. It has a pressurizing chamber surface 4-1 and a discharge hole surface 4-2 provided on the lower side. The piezoelectric actuator substrate 40 is placed on the pressurizing chamber surface 4-1, and the liquid is discharged from the discharge hole 8 opened on the discharge hole surface 4-2. The plurality of plates 4a to 4m can be formed of metal, alloy, or resin. In addition, the 1st flow path member 4 may integrally form with resin, without laminating | stacking several plate 4a-4m.

  The first flow path member 4 includes a plurality of first common flow paths 20, a plurality of second common flow paths 24, a plurality of end flow paths 28, a plurality of discharge units 15, and a plurality of dummy discharge units 17. And are formed.

  The first common flow path 20 is provided so as to extend from the first direction D1 to the fourth direction D4, and is formed to communicate with the opening 20a. A plurality of first common flow paths 20 are arranged in the second direction D2 to the fifth direction D5.

  The second common flow path 24 is provided so as to extend from the fourth direction D4 to the first direction D1, and is formed so as to communicate with the opening 24a. A plurality of the second common flow paths 24 are arranged in the second direction D2 to the fifth direction D5, and are arranged between the adjacent first common flow paths 20. Therefore, the first common channel 20 and the second common channel 24 are alternately arranged from the second direction D2 toward the fifth direction D5.

  A damper 30 is formed in the second common flow path 24 of the first flow path member 4, and a space 32 facing the second common flow path 24 is disposed via the damper 30. The damper 30 has a first damper 30a and a second damper 30b. The space 32 has a first space 32a and a second space 32b. The first space 32a is provided above the second common flow path 24 through which the liquid flows through the first damper 30a. The second space 32b is provided below the second common flow path 24 through which the liquid flows via the second damper 30b.

  The first damper 30 a is formed over substantially the entire area above the second common flow path 24. Therefore, when viewed in plan, the first damper 30 a has the same shape as the second common flow path 24. The first space 32a is formed over substantially the entire area above the first damper 30a. Therefore, when viewed in plan, the first space 32 a has the same shape as the second common flow path 24.

  The second damper 30 b is formed over substantially the entire area below the second common flow path 24. Therefore, when viewed in plan, the second damper 30 b has the same shape as the second common flow path 24. Further, the second space 32b is formed in substantially the entire area below the second damper 30b. Therefore, when viewed in plan, the second space 32 b has the same shape as the second common flow path 24. Since the first flow path member 4 is provided with the damper 30 in the second common flow path 24, the pressure fluctuation of the second common flow path 24 can be alleviated and fluid crosstalk is less likely to occur.

  The first damper 30a and the first space 32a can be formed by forming grooves in the plates 4d and 4e by half-etching and bonding so that the grooves face each other. At this time, the remaining portion left by the half etching of the plate 4e becomes the first damper 30a. Similarly, the second damper 30b and the second space 32b can be produced by forming grooves in the plates 4k and 4l by half etching.

  The end channel 28 is formed at the end of the first channel member 4 in the second direction D2 and the end of the fifth direction D5. The end channel 28 has a wide portion 28a, a narrowed portion 28b, and openings 28c and 28d. The liquid supplied from the opening 28c flows through the end channel 28 by flowing through the wide portion 28a, the narrowed portion 28b, the wide portion 28a, and the opening 28d in this order. Thereby, the liquid is present in the end channel 28 and the liquid flows through the end channel 28, and the temperature of the first channel member 4 positioned around the end channel 28 is made uniform by the liquid. Is done. Therefore, the possibility that the first flow path member 4 is radiated from the end portion in the second direction D2 and the end portion in the fifth direction D5 is reduced.

(Discharge unit)
The discharge unit 15 will be described with reference to FIGS. The discharge unit 15 includes a discharge hole 8, a pressurizing chamber 10, a first individual channel 12, a second individual channel 14, and a third individual channel 16. In the liquid discharge head 2, the liquid is supplied from the first individual channel 12 and the second individual channel 14 to the pressurizing chamber 10, and the third individual channel 16 collects the liquid from the pressurizing chamber 10. . Although details will be described later, the channel resistance of the second individual channel 14 is lower than the channel resistance of the first individual channel 12.

  The discharge unit 15 is provided between the adjacent first common flow path 20 and the second common flow path 24, and is formed in a matrix in the planar direction of the first flow path member 4. The discharge unit 15 has a discharge unit column 15a and a discharge unit row 15b. In the discharge unit row 15a, the discharge units 15 are arranged from the first direction D1 toward the fourth direction D4. In the discharge unit row 15b, the discharge units 15 are arranged from the second direction D2 toward the fifth direction D5.

  The pressurizing chamber 10 has a pressurizing chamber row 10c and a pressurizing chamber row 10d. Moreover, the discharge hole 8 has a discharge hole row 8a and a discharge hole row 8b. Similarly, the discharge hole row 8a and the pressurizing chamber row 10c are arranged from the first direction D1 to the fourth direction D4. Similarly, the discharge hole row 8b and the pressurizing chamber row 10d are arranged from the second direction D2 toward the fifth direction D5.

  The angles formed by the first direction D1 and the fourth direction D4 and the second direction D2 and the fifth direction D5 are deviated from a right angle. For this reason, the ejection holes 8 belonging to the ejection hole array 8a arranged along the first direction D1 are displaced in the second direction D2 by the deviation from the right angle. And since the discharge hole row | line | column 8a is arrange | positioned along with the 2nd direction D2, the discharge hole 8 which belongs to the different discharge hole row | line | column 8a is shifted | deviated and arranged in the 2nd direction D2 by that much. Together, the discharge holes 8 of the first flow path member 4 are arranged at regular intervals in the second direction D2. Thus, printing can be performed so as to fill a predetermined range with pixels formed by the discharged liquid.

  In FIG. 6, when the discharge holes 8 are projected in the third direction D3 and the sixth direction D6, 32 discharge holes 8 are projected in the range of the virtual straight line R, and each discharge hole 8 is spaced 360 dpi within the virtual straight line R. Lined up. Thus, if the recording medium P is conveyed and printed in a direction orthogonal to the virtual straight line R, printing can be performed with a resolution of 360 dpi.

  The dummy discharge unit 17 is provided between the first common flow path 20 positioned closest to the second direction D2 and the second common flow path 24 positioned closest to the second direction D2. The dummy discharge unit 17 is also provided between the first common flow path 20 located closest to the fifth direction D5 and the second common flow path 24 located closest to the fifth direction D5. The dummy discharge unit 17 is provided to stabilize the discharge of the discharge unit row 15a located closest to the second direction D2 or the fifth direction D5.

  As shown in FIGS. 7 and 8, the pressurizing chamber 10 includes a pressurizing chamber main body 10a and a partial flow path 10b. The pressurizing chamber body 10a has an opening 10h that opens upward (on the opposite side to the discharge side). The shape of the pressurizing chamber body 10a is, for example, a column having a relatively small height. Therefore, in the following, the description of the shape (planar shape) of the pressurizing chamber body 10a in plan view is also the description of the shape of the opening 10h or the lower surface of the pressurizing chamber body 10a. Here, etching errors (such as undercut) are ignored. The pressurizing chamber body 10a has a circular shape in plan view, and a partial flow path 10b extends downward from a part of the lower surface of the pressurizing chamber body 10a. The pressurizing chamber body 10a pressurizes the liquid in the partial flow path 10b by receiving pressure from the displacement element 48 provided on the pressurizing chamber body 10a.

  The pressurizing chamber main body 10a has a substantially disc shape, and the planar shape is circular. When the planar shape is circular, the displacement amount and the volume change of the pressurizing chamber 10 caused by the displacement can be increased. The partial flow path 10b has a substantially cylindrical shape whose diameter is smaller than that of the pressurizing chamber body 10a, and the planar shape is a circular shape. Moreover, the partial flow path 10b is accommodated in the pressurization chamber main body 10a, when it sees from the pressurization chamber surface 4-1.

  In addition, the partial flow path 10b may have a conical shape or a truncated cone shape whose sectional area decreases toward the discharge hole 8 side. Thereby, the width | variety of the 1st common flow path 20 and the 2nd common flow path 24 can be enlarged, and the difference of the above-mentioned pressure loss can be made small.

  The pressurizing chambers 10 are arranged along both sides of the first common flow path 20 and constitute a total of two pressurizing chamber rows 10c, one on each side. The first common flow path 20 and the pressurizing chambers 10 arranged on both sides thereof are connected via the first individual flow path 12 and the second individual flow path 14.

  Further, the pressurizing chambers 10 are arranged along both sides of the second common flow path 24, and constitute a total of two pressurizing chamber rows 10c, one on each side. The second common flow path 24 and the pressurizing chambers 10 arranged on both sides thereof are connected via the third individual flow path 16.

  The first individual flow path 12, the second individual flow path 14, and the third individual flow path 16 will be described with reference to FIG.

  The first individual flow path 12 connects the first common flow path 20 and the pressurizing chamber body 10a. The first individual flow path 12 extends upward from the upper surface of the first common flow path 20, then extends in the fifth direction D5, extends in the fourth direction D4, and then upwards again. It extends and is connected to the lower surface of the pressurizing chamber body 10a.

  The second individual flow path 14 connects the first common flow path 20 and the partial flow path 10b. The second individual flow path 14 extends from the lower surface of the first common flow path 20 in the fifth direction D5, extends in the first direction D1, and is then connected to the side surface of the partial flow path 10b.

  The third individual flow path 16 connects the second common flow path 24 and the partial flow path 10b. The third individual flow channel 16 extends from the side surface of the second common flow channel 24 in the second direction D2, extends in the fourth direction D4, and is connected to the side surface of the partial flow channel 10b.

  The channel resistance of the second individual channel 14 is lower than the channel resistance of the first individual channel 12. In order to make the channel resistance of the second individual channel 14 lower than the channel resistance of the first individual channel 12, for example, the thickness of the plate 4l on which the second individual channel 14 is formed is changed to the first individual channel 14. What is necessary is just to make it thicker than the thickness of the plate 4c in which the flow path 12 is formed. Further, the width of the second individual flow path 14 may be wider than the width of the first individual flow path 12 in plan view. Further, in plan view, the length of the second individual flow path 14 may be shorter than the length of the first individual flow path 12.

  With the configuration as described above, in the first flow path member 4, the liquid supplied to the first common flow path 20 via the opening 20 a is added via the first individual flow path 12 and the second individual flow path 14. A part of the liquid flows into the pressure chamber 10 and is discharged from the discharge hole 8. The remaining liquid flows from the pressurizing chamber 10 into the second common flow path 24 via the third individual flow path 16, and from the first flow path member 4 to the second flow path member 6 via the opening 24a. To be discharged.

(Piezoelectric actuator)
The piezoelectric actuator substrate 40 will be described with reference to FIGS. A piezoelectric actuator substrate 40 including a displacement element 48 is bonded to the upper surface of the first flow path member 4, and each displacement element 48 is disposed on the pressurizing chamber 10. The piezoelectric actuator substrate 40 occupies a region having substantially the same shape as the pressurizing chamber group formed by the pressurizing chamber 10. Further, the opening 10 h of each pressurizing chamber 10 is closed by joining the piezoelectric actuator substrate 40 to the pressurizing chamber surface 4-1 of the first flow path member 4.

  The piezoelectric actuator substrate 40 has a laminated structure composed of two piezoelectric ceramic layers 40a and 40b that are piezoelectric bodies. These piezoelectric ceramic layers 40a and 40b have a thickness of 50 μm or less, more specifically about 20 μm, respectively. Both of the piezoelectric ceramic layers 40 a and 40 b extend so as to straddle the plurality of pressure chambers 10.

The piezoelectric ceramic layers 40a, 40b may, for example, strength with a dielectric, lead zirconate titanate (PZT), NaNbO ₃ system, BaTiO ₃ system, (BiNa) NbO ₃ system, such as BiNaNb ₅ O ₁₅ system Made of ceramic material. The piezoelectric ceramic layer 40b functions as a vibration plate and does not necessarily need to be a piezoelectric body. Instead, a ceramic layer other than a piezoelectric body, a metal plate, or a resin plate may be used. The diaphragm may be configured as if it is also used as a member constituting a part of the first flow path member 4. For example, unlike the illustrated example, the diaphragm may have an opening across the entire pressure chamber surface 4-1, and may have openings facing the openings 20a, 24a, 28c, and 28d.

  In the liquid ejection head 2, the boundary between the first flow path member 4 and the piezoelectric actuator substrate 40 may be determined based on the position of the opening 10 h of the pressurizing chamber 10 regardless of the manufacturing process. For example, when the first flow path member 4 and the piezoelectric actuator substrate 40 are bonded, and the first flow path member 4 and a diaphragm (or a part of them) closing the opening 10h; The range of the first flow path member 4 and the piezoelectric actuator substrate 40 in the laminate does not change depending on the case where the piezoelectric actuator substrate 40 is bonded to the diaphragm (or the part of the layers).

  A common electrode 42, an individual electrode 44, and a connection electrode 46 are formed on the piezoelectric actuator substrate 40. The common electrode 42 is formed over substantially the entire surface in the region between the piezoelectric ceramic layer 40a and the piezoelectric ceramic layer 40b. The individual electrode 44 is disposed at a position facing the pressurizing chamber 10 on the upper surface of the piezoelectric actuator substrate 40.

  A portion sandwiched between the individual electrode 44 and the common electrode 42 of the piezoelectric ceramic layer 40a is polarized in the thickness direction, and becomes a displacement element 48 having a unimorph structure that is displaced when a voltage is applied to the individual electrode 44. Yes. Therefore, the piezoelectric actuator substrate 40 has a plurality of displacement elements 48.

  The common electrode 42 can be formed of a metal material such as Ag—Pd, and the thickness of the common electrode 42 can be about 2 μm. The common electrode 42 is connected to a common electrode surface electrode (not shown) on the piezoelectric ceramic layer 40a through a via hole formed through the piezoelectric ceramic layer 40a, and is grounded through the common electrode surface electrode. , Held at ground potential.

  The individual electrode 44 is made of a metal material such as Au, and has an individual electrode main body 44a and an extraction electrode 44b. As shown in FIG. 7C, the individual electrode main body 44a is a portion that overlaps the pressurizing chamber main body 10a (opening 10h) and the extraction electrode 44b is located outside the pressurizing chamber main body 10a. Part.

  The individual electrode main body 44a has a central portion 44aa and a connection portion 44ab protruding from the central portion 44aa. The central portion 44aa constitutes a large part of the individual electrode main body 44a and is a portion responsible for voltage application to the piezoelectric ceramic layer 40a. The connection portion 44ab is a portion that connects the central portion 44aa and the extraction electrode 44b.

  The central portion 44aa is formed in a substantially circular shape in plan view and is smaller than the pressurizing chamber body 10a. From another viewpoint, the planar shape of the central portion 44aa is substantially similar to the pressurizing chamber body 10a. The planar shape of the connecting portion 44ab is, for example, a shape (rectangular shape) extending linearly with a certain width from the inside to the outside of the pressurizing chamber body 10a.

  The extraction electrode 44b is extracted from the individual electrode body 44a. The shape of the extraction electrode 44b is, for example, a shape (rectangular shape) extending linearly with a certain width in a direction away from the pressurizing chamber body 10a of the pressurizing chamber body 10a. The connection part 44ab of the extraction electrode 44b and the individual electrode main body 44a is connected in a straight line with the same width, for example. A connection electrode 46 is formed on the end of the extraction electrode 44b opposite to the individual electrode main body 44a.

  The connection electrode 46 is made of, for example, silver-palladium containing glass frit, and has a convex shape with a thickness of about 15 μm. The connection electrode 46 is electrically joined to an electrode provided in the signal transmission unit 60.

  The liquid ejection head 2 displaces the displacement element 48 according to the drive signal supplied to the individual electrode 44 via the driver IC 62 and the like under the control of the control unit 76. As a driving method, so-called striking driving can be used.

(Details and operation of the discharge unit)
The discharge unit 15 of the liquid discharge head 2 will be described in detail with reference to FIG.

  The discharge unit 15 includes a discharge hole 8, a pressurizing chamber 10, a first individual channel 12, a second individual channel 14, and a third individual channel 16. The first individual channel 12 and the second individual channel 14 are connected to the first common channel 20 (see FIG. 8), and the third individual channel 16 is connected to the second common channel 24 (see FIG. 8). )It is connected to the.

  The first individual flow path 12 is connected to the first direction D1 side of the pressurizing chamber body 10a in the pressurizing chamber 10. The second individual flow path 14 is connected to the fourth direction D4 side of the partial flow path 10b in the pressurizing chamber 10. The third individual flow channel 16 is connected to the first direction D1 side of the partial flow channel 10b in the pressurizing chamber 10.

  The liquid supplied from the first individual flow channel 12 flows downward through the partial flow channel 10 b through the pressurizing chamber body 10 a, and a part of the liquid is discharged from the discharge hole 8. The liquid that has not been discharged from the discharge hole 8 is collected outside the discharge unit 15 via the third individual flow path 16.

  A part of the liquid supplied from the second individual flow path 14 is discharged from the discharge hole 8. The liquid that has not been discharged from the discharge hole 8 flows upward in the partial flow path 10 b and is collected outside the discharge unit 15 via the third individual flow path 16.

  As shown in FIG. 9, the liquid supplied from the first individual flow path 12 flows through the pressurizing chamber body 10 a and the partial flow path 10 b and is discharged from the discharge holes 8. The flow of the liquid in the conventional discharge unit flows uniformly in a substantially straight line from the central portion of the pressurizing chamber main body 10a toward the discharge hole 8, as indicated by a broken line.

  When such a flow occurs, the liquid does not easily flow in the vicinity of the region 80 in the pressurizing chamber 10 on the side opposite to the portion to which the second individual flow path 14 is connected. There is a possibility that an area where the liquid stays is generated.

  On the other hand, in the discharge unit 15, the first individual flow path 12 and the second individual flow path 14 are connected to the pressurizing chamber 10, and liquid is supplied to the pressurizing chamber 10 from these flow paths.

  Therefore, the flow of liquid supplied from the second individual flow path 14 to the pressurizing chamber 10 can collide with the flow of liquid supplied from the first individual flow path 12 to the discharge hole 8. As a result, the flow of the liquid supplied from the pressurizing chamber 10 to the discharge hole 8 is less likely to flow in a substantially straight line, and a region where the liquid stays in the pressurizing chamber 10 can be hardly generated.

  That is, the position of the liquid retention point generated by the flow of the liquid supplied from the pressurizing chamber 10 to the discharge hole 8 is moved by the collision with the flow of the liquid supplied from the pressurizing chamber 10 to the discharge hole 8. Thus, a region where the liquid stays in the pressurizing chamber 10 can be made difficult to occur.

  The pressurizing chamber 10 has a pressurizing chamber main body 10a and a partial flow path 10b, the first individual flow path 12 is connected to the pressurization chamber main body 10a, and the second individual flow path 14 is a partial flow path. 10b. Therefore, the first individual channel 12 supplies the liquid so that it flows through the entire pressurizing chamber 10, and the region where the liquid stays in the partial channel 10 b due to the flow of the liquid supplied from the second individual channel 14. Is less likely to occur.

  Further, the third individual flow channel 16 is connected to the partial flow channel 10b. Therefore, the liquid flow flowing from the second individual flow path 14 toward the third individual flow path 16 crosses the inside of the partial flow path 10b. As a result, it is possible to flow the liquid flowing from the second individual flow path 14 toward the third individual flow path 16 so as to cross the flow of the liquid supplied from the pressurizing chamber body 10 a to the discharge hole 8. Therefore, a region where the liquid stays in the partial flow path 10b is less likely to occur.

(Extended room)
As shown in FIGS. 7 and 10, the first flow path member 4 includes an expansion chamber 25 formed as if the pressurizing chamber body 10 a is expanded. The expansion chamber 25 is opened to the piezoelectric actuator substrate 40 side like the pressurizing chamber 10 (having an opening 25h (see FIG. 10)). The shape of the expansion chamber 25 is, for example, a columnar body. Therefore, in the following, the description of the shape (planar shape) of the expansion chamber 25 in plan view is also the description of the shape of the opening 25h or the lower surface of the expansion chamber 25. Here, etching errors (such as undercut) are ignored. The extension chamber 25 (opening 25h) protrudes from the pressurizing chamber body 10a (opening 10h) and overlaps with the extraction electrode 44b in a plan view.

  By forming such an expansion chamber 25, for example, immediately below the extraction electrode 44b, the inner wall of the pressurizing chamber body 10a and the piezoelectric actuator substrate 40 are not in contact with each other, or contact is reduced. Here, when a voltage is applied to the common electrode 42 and the individual electrode 44 for discharging liquid, a voltage is applied to the piezoelectric ceramic layer 40a not only directly below the central portion 44aa but also directly below the extraction electrode 44b. . Therefore, unlike the present embodiment, when the inner wall of the pressurizing chamber body 10a and the piezoelectric actuator substrate 40 are in contact immediately below the extraction electrode 44b, for example, due to contraction or extension in the planar direction of the piezoelectric ceramic layer 40a, There is a possibility that the inner wall of the pressurizing chamber body 10a vibrates in the direction of the inner wall. However, as described above, the expansion chamber 25 causes the inner wall of the pressurizing chamber body 10a and the piezoelectric actuator substrate 40 to be in non-contact with each other or the contact is reduced, so that such vibration of the inner wall is reduced. As a result, for example, the possibility that the discharge characteristics are deteriorated due to unintended vibration of the inner wall of the pressurizing chamber body 10a is reduced.

  The effect as described above becomes prominent when the portion of the piezoelectric ceramic layer 40a that overlaps the extraction electrode 44b is polarized in the same manner as the portion that overlaps the individual electrode main body 44a. For example, when the piezoelectric actuator substrate 40 or the head main body 2a is manufactured and then polarized by applying a voltage to the individual electrode 44 and the common electrode 42, the piezoelectric ceramic layer 40a is also polarized immediately below the extraction electrode 44b. become. Such polarization after assembling the piezoelectric actuator substrate 40 or the head body 2a is often performed when the piezoelectric ceramic layer 40a is relatively thin (for example, 50 μm or less). This is because if the piezoelectric ceramic layer 40a is relatively thin, the influence of the deformation of the piezoelectric ceramic layer 40a caused by the polarization process on the subsequent manufacturing process becomes relatively large.

  The pressurizing chamber body 10a is usually circular, elliptical (not necessarily mathematically elliptical), oval (arced shape in which the short side of the rectangle swells outward), rhombus, parallelogram, etc. Often has a certain shape. On the other hand, the expansion chamber 25 is a portion that “projects” from the pressurizing chamber body 10a. Therefore, in the case where an opening communicating with the inside of the pressurizing chamber 10 is opened on the upper surface of the first flow path member 4, the opening is composed only of the opening 10h of the pressurizing chamber 10 or in addition to the opening 10h. In general, it can be easily determined from the shape of the opening whether the opening 25h of the expansion chamber 25 is included. In addition, in view of the functions of the pressurizing chamber 10 and the expansion chamber 25, the area of the opening 10h is clearly larger than the area of the opening 25h. Further, even if there is a protruding portion in the opening, the portion is not the opening 25 h of the expansion chamber 25 if there is no overlap with the individual electrode 44 (the extraction electrode 44 b).

  When it is difficult to determine whether or not the opening that opens to the upper surface of the first flow path member 4 has a protruding portion (opening 25h of the expansion chamber 25), for example, a mathematical convexity as follows: You may determine using the concept of a set.

  The planar shape of the pressurizing chamber body 10a is often, for example, mathematically convex (consisting of a convex set). To be surely described, that the planar shape is convex means that an arbitrary point on a line segment connecting two arbitrary points included in the planar shape is included in the planar shape. Examples of such a shape include a shape having a convex closed curve as an outer edge or a convex polygon. Examples of the shape having the convex closed curve as the outer edge include a circle or an ellipse. Examples of the convex polygon include a rhombus or a parallelogram. In addition, examples of the convex shape include an oval shape or a shape obtained by chamfering a corner of a convex polygon with a curve.

  When the expansion chamber 25 protruding from the pressurizing chamber body 10a is provided, the planar shape of the pressurizing chamber body 10a and the expansion chamber 25 as a whole may not be mathematically convex (consisting of a non-convex set). Many. To be sure, the case where the planar shape is not convex means that any point on a line segment connecting any two points included in the planar shape can be located outside the planar shape. Note that a non-convex set word is a negative expression, but is more commonly used than a concave set word.

  Therefore, for example, if the planar shape of the opening opened on the upper surface of the first flow path member 4 is convex, it can be determined that the opening consists only of the opening 10h of the pressurizing chamber body 10a. Moreover, if the planar shape of the opening opened on the upper surface of the first flow path member 4 is non-convex, it can be determined that the opening 25h of the expansion chamber 25 can be included in addition to the opening 10h. In the case of non-convexity, since the outer edge of the planar shape is formed with a concave corner or curved portion on the outside, the pressurizing chamber main body 10a and the protruding portion (expansion chamber 25) are defined with the position as a boundary. ) Can be specified. Note that the boundary between the two is not necessarily clear. It suffices if the presence of the protruding portion can be confirmed and whether or not the protruding portion overlaps with the individual electrode can be determined.

  Note that the determination method using the concept of the following convex set is a case where the presence or absence of the expansion chamber 25 cannot be easily determined. Therefore, for example, the shape of the opening 10h of the pressurizing chamber 10 is not necessarily convex.

  As described above, the piezoelectric actuator substrate 40 further includes the connection electrode 46 that overlaps the opposite side of the piezoelectric ceramic layer 40a with respect to the end of the extraction electrode 44b opposite to the individual electrode body 44a. . The opening 25h of the expansion chamber 25 has, for example, an overlap with the connection electrode 46 in plan view that is less than half of the area of the connection electrode 46 (area in plan view).

  Therefore, for example, compared to a mode in which the opening 25 h overlaps the entire connection electrode 46 in a plan view (this mode is also included in the technology according to the present disclosure), the piezoelectric actuator substrate 40 is directly below the connection electrode 46. The contact area with the first flow path member 4 is large. Thereby, for example, the piezoelectric actuator substrate 40 is reinforced directly below the connection electrode 46 in terms of rigidity. As a result, for example, when the electrode provided in the signal transmission unit 60 and the connection electrode 46 are joined, the possibility that the piezoelectric actuator substrate 40 is deformed immediately below the connection electrode 46 is reduced. As a result, the joining accuracy is improved and the reliability of the liquid discharge head 2 is improved.

  In the configuration in which the expansion chamber 25 is provided, the planar shape of the opening 10h of the pressurizing chamber 10 is, for example, a circle.

  Therefore, for example, when the liquid in the expansion chamber 25 is pressurized by the piezoelectric actuator substrate 40 and a pressure wave propagates from the expansion chamber 25 to the pressure chamber main body 10a, the pressure wave propagates over a wide angle in a plan view. Therefore, it is easy to be dispersed. As a result, for example, the influence of the expansion chamber 25 on the ejection of droplets is mitigated. Moreover, even if the expansion chamber 25 protrudes from any position of the pressurizing chamber main body 10a, the propagation mode of the pressure from the expansion chamber 25 to the pressurizing chamber main body 10a is substantially constant. As a result, for example, when the positions of the extraction electrodes 44b are different among the plurality of discharge units 15, variations in discharge characteristics among the plurality of discharge units 15 due to the difference are reduced.

  Further, on the discharge side surface of the expansion chamber 25, a partial flow path 10b, a flow path for supplying liquid (the first individual flow path 12 or the second individual flow path 14), and a flow for collecting liquid are provided. None of the paths (third individual flow paths 16) are open.

  Therefore, for example, compared to an aspect in which the lower surface of the expansion chamber 25 and the partial flow path 10b or the first individual flow path 12 are connected (this aspect is also included in the technology according to the present disclosure), the piezoelectric actuator substrate 40 The effect of the pressure applied to the expansion chamber 25 on the pressure or flow in the pressurizing chamber 10 is reduced. As a result, for example, the ejection characteristics are improved.

  In plan view, the opening position (connection position) of the partial flow path 10b with respect to the pressurizing chamber body 10a is eccentric to one side (fourth direction D4 side) in a predetermined direction with respect to the pressurizing chamber body 10a. The opening 25h of the expansion chamber 25 protrudes from a portion on the one side (the fourth direction D4 side) with respect to the area center of gravity P1 (FIG. 7C) of the opening 10h of the pressurizing chamber 10, for example.

  Therefore, for example, the pressure wave generated in the expansion chamber 25 propagates while diffusing from the fourth direction D4 side to the area centroid P1 side in the pressurizing chamber body 10a, and subsequently, from the area centroid P1 to the first direction D1 side. Propagate while concentrating on. The pressure wave is diffracted and enters the partial flow path 10b in the process of diffusing. As a result, for example, the influence of the pressure in the expansion chamber 25 on the discharge is reduced as compared with an aspect (the aspect is also included in the technology according to the present disclosure) that enters the partial flow path 10b in the process of concentration of pressure waves. be able to.

  Whether or not the opening of the partial flow path 10b to the pressurizing chamber body 10a is eccentric with respect to the pressurizing chamber body 10a may be determined, for example, based on the center of gravity of both areas. The area centroid is a position where the first moment around the area centroid is zero when it is described as it is.

  In plan view, the opening position (connection position) of the partial flow path 10b with respect to the pressurizing chamber body 10a is eccentric to one side (fourth direction D4 side) in a predetermined direction with respect to the pressurizing chamber body 10a. The opening 25h of the expansion chamber 25 protrudes from the opening 10h of the pressurizing chamber 10 in a direction that intersects the predetermined direction (fourth direction D4), for example.

  Therefore, the traveling direction of the pressure wave entering the partial flow path 10b from the area center of gravity P1 of the pressurizing chamber body 10a and the pressure wave propagating from the expansion chamber 25 to the pressurizing chamber body 10a are easily shifted. As a result, for example, a standing wave is generated over a wide range of the pressurizing chamber body 10a as compared with an aspect in which both traveling directions are the same or opposite (the aspect is also included in the technology according to the present disclosure). The fear is reduced. That is, the risk of unintended relatively large pressure fluctuations is reduced.

  Moreover, the thickness (size from the discharge side to the opposite side) of the expansion chamber 25 is equal to the thickness of the pressurizing chamber body 10a.

  Therefore, for example, the inner wall of the pressurizing chamber body 10a at the position overlapping the extraction electrode 44b is cut out by the expansion chamber 25 over the entire thickness of the pressurizing chamber body 10a. As a result, for example, the influence of the vibration of the inner wall on the pressure of the pressurizing chamber body 10a is more reliably reduced.

  In planar perspective, the entire width of the portion of the extraction electrode 44b from the opening 10h of the pressurizing chamber 10 to at least halfway is accommodated in the opening 25h of the expansion chamber 25.

  That is, the entire portion of the inner wall of the pressurizing chamber main body 10 a that overlaps the extraction electrode 44 b in plan view is cut out by the expansion chamber 25. Therefore, for example, the influence of the vibration of the inner wall on the pressure of the pressurizing chamber body 10a is more reliably reduced.

  The specific shape and position of the expansion chamber 25 in plan view may be set as appropriate according to the shape and position of the extraction electrode 44b. In the illustrated example, the expansion chamber 25 has a shape (generally rectangular) extending linearly with a constant width, like the extraction electrode 44b, and its width and length are smaller than those of the extraction electrode 44b.

  In the above embodiment, the piezoelectric ceramic layer 40a is an example of a piezoelectric layer. The opening 10h is an example of a pressurizing chamber opening. The opening 25h is an example of an expansion chamber opening. The conveyance rollers 74a to 74d are an example of a conveyance unit.

  The aspect of this indication is not limited to the said embodiment, A various change is possible unless it deviates from the meaning.

  The configuration of the flow path connected to the pressurizing chamber and used for supplying or collecting the liquid is not limited to that illustrated in the embodiment. For example, in FIG. 9, the direction extending from the second individual flow path 14 and / or the partial flow path 10 b of the third individual flow path 16 may be reversed from the illustration. Further, for example, the liquid may be supplied from the first individual channel 12 and the third individual channel 16 to the pressurizing chamber 10 and the liquid may be recovered from the second individual channel 14. The first individual flow path 12 may be used for liquid recovery. Further, one of the three individual flow paths may be used for supplying the liquid, and two may be used for collecting the liquid. It is not necessary to provide three individual flow paths. For example, only one liquid supply (for example, only the first individual flow path 12) may be provided, or one supply flow and recovery. A total of two of the two may be provided.

  The shape of the pressurizing chamber opening (opening 10h) and the shape of the central portion (44aa) of the individual electrode main body are not limited to a circle. For example, you may be set as the various shape enumerated as an example of the shape which is convex in description of embodiment.

  The shape of the expansion chamber opening (opening 25h) and the shape of the extraction electrode (44b) are not limited to a rectangle. For example, the extraction electrode may extend not in a straight line but in a curved line. Depending on the shape of the extraction electrode, the opening of the expansion chamber may also extend in a curved shape. In addition, for example, the extraction electrode may have a pad-like portion with a wide width at the tip (the side opposite to the individual electrode main body). In such a shape of the extraction electrode, the opening of the expansion chamber may or may not overlap with the pad-shaped portion.

  Further, the shape of the opening of the expansion chamber may not reflect the shape of the extraction electrode. For example, in the case where a rectangular extraction electrode is provided, the shape of the expansion chamber opening is a semicircular shape with the pressurizing chamber side as the center, or an isosceles triangle with the pressurizing chamber side as the base. Or you may.

  Further, as illustrated in the embodiment, the expansion chamber opening may have a protruding amount from the pressurizing chamber larger than the width, or, conversely, the width may be larger than the protruding amount. The thickness of the expansion chamber may not be equal to the thickness of the pressurizing chamber body. For example, the expansion chamber may be formed by half-etching the upper surface of the plate 4a, and may have a thickness that is approximately half the thickness of the pressurizing chamber body 10a. In this case, it is possible to suppress a decrease in rigidity of the plate 4a while suppressing a decrease in discharge characteristics due to unintended vibration of the pressurizing chamber body 10a. Further, the width of the expansion chamber may not be equal to or greater than the width of the extraction electrode.

  The piezoelectric actuator substrate is not limited to a unimorph type, and may be a bimorph type.

  The specific configuration described in the embodiment does not need to hold for all the discharge units provided with the expansion chamber. For example, the positional relationship between the expansion chamber and other spaces (pressurization chamber body, partial flow path, or individual flow path) does not need to hold for all the discharge units. Even if a specific effect is produced only in some of the discharge units, the reliability of the liquid discharge unit is improved.

DESCRIPTION OF SYMBOLS 1 ... Color inkjet printer 2 ... Liquid discharge head 2a ... Head main body 4 ... 1st flow-path member 4a-4m ... Plate 4-1 ... Pressurization chamber surface 4-2. ..Discharge hole surface 6 ... second flow path member 8 ... discharge hole 10 ... pressure chamber 10a ... pressure chamber body 10b ... partial flow channel 10h ... opening (pressurization) Room opening)
DESCRIPTION OF SYMBOLS 12 ... 1st separate flow path 14 ... 2nd separate flow path 15 ... Discharge unit 16 ... 3rd separate flow path 20 ... 1st common flow path 22 ... 1st integrated flow Path 24 ... Second common flow path 25 ... Expansion chamber 25h ... Opening (expansion chamber opening)
26 ... 2nd integrated flow path 28 ... End flow path 30 ... Damper 32 ... Damper chamber 40 ... Piezoelectric actuator substrate 40a ... Piezoelectric ceramic layer (piezoelectric layer)
42 ... Common electrode 44 ... Individual electrode 46 ... Connection electrode 48 ... Displacement element 50 ... Housing 52 ... Heat sink 54 ... Wiring board 56 ... Pressing member 58 ..Elastic member 60 ... Signal transmission part 62 ... Driver IC
70: Head mounting frame 72: Head group 74a, 74b, 74c, 74d ... Conveying roller (conveying unit)
76: Control unit P ... Recording medium D1 ... First direction D2 ... Second direction D3 ... Third direction D4 ... Fourth direction D5 ... Fifth direction D6 ...・ 6th direction

Claims (9)

A plurality of discharge holes that open to the discharge side, and a plurality of pressurization chamber openings that open to the opposite side of the discharge side, and that are connected to the plurality of discharge holes, respectively. A flow path member provided with a pressurizing chamber;
A piezoelectric actuator substrate that overlaps the opposite side of the flow path member from the discharge side and closes the plurality of pressurizing chamber openings;
With
The piezoelectric actuator substrate is
A piezoelectric layer having a width over a plurality of the pressurizing chamber openings;
A common electrode that overlaps the flow path member side with respect to the piezoelectric layer, and that has a width across the plurality of pressurizing chamber openings;
A plurality of individual electrodes that are overlapped on the opposite side of the flow path member with respect to the piezoelectric layer, and that are respectively overlapped with the plurality of pressurizing chamber openings in a plan view,
The individual electrodes are in plan perspective,
An individual electrode body overlapping the pressurizing chamber opening;
A lead electrode connected to the individual electrode main body and positioned outside the pressurizing chamber opening; and
The flow path member further includes an expansion chamber that opens to the piezoelectric actuator substrate side and has an expansion chamber opening that protrudes from the pressurization chamber opening and overlaps the extraction electrode in a plan view. head. The piezoelectric actuator substrate further includes a connection electrode that overlaps the opposite side of the piezoelectric layer with respect to the end of the extraction electrode opposite to the individual electrode body,
The liquid ejection head according to claim 1, wherein the extension chamber opening has an overlap with the connection electrode that is less than half of an area of the connection electrode in a plan view. The liquid discharge head according to claim 1, wherein a planar shape of the opening of the pressurizing chamber is a circle. The pressure chamber is
A pressurizing chamber body having the pressurizing chamber opening;
A partial flow path extending from a part of the discharge side surface of the pressurizing chamber main body to the discharge hole, and
Any of the partial flow path, the flow path for supplying liquid, and the flow path for collecting liquid is not open on the discharge side surface of the expansion chamber. 2. A liquid discharge head according to item 1. The pressure chamber is
A pressurizing chamber body having the pressurizing chamber opening;
A partial flow path extending from a part of the discharge side surface of the pressurizing chamber main body to the discharge hole, and
In plan view, the opening position of the partial flow path with respect to the pressurizing chamber body is eccentric to one side in a predetermined direction with respect to the pressurizing chamber body,
5. The liquid discharge head according to claim 1, wherein the extension chamber opening protrudes from a portion on the one side with respect to the center of area of the pressurizing chamber opening. The pressure chamber is
A pressurizing chamber body having the pressurizing chamber opening;
A partial flow path extending from a part of the discharge side surface of the pressurizing chamber main body to the discharge hole, and
In plan view, the opening position of the partial flow path with respect to the pressurizing chamber body is eccentric to one side in a predetermined direction with respect to the pressurizing chamber body,
The liquid ejection head according to claim 1, wherein the expansion chamber opening protrudes from the pressurization chamber opening in a direction intersecting the predetermined direction. The pressure chamber is
A pressurizing chamber body having the pressurizing chamber opening;
A partial flow path extending from a part of the discharge side surface of the pressurizing chamber main body to the discharge hole, and
The thickness of the expansion chamber from the discharge side to the opposite side thereof is equivalent to the thickness of the pressurizing chamber main body from the discharge side to the opposite side thereof. The liquid discharge head described. The liquid ejection head according to any one of claims 1 to 7, wherein the entire width of a portion of the extraction electrode from the opening of the pressurizing chamber to at least halfway thereof is accommodated in the opening of the expansion chamber. A liquid discharge head according to any one of claims 1 to 8,
A transport unit for transporting a recording medium to the liquid discharge head;
A control unit for controlling the liquid ejection head;
A recording apparatus comprising:

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