JP6224499B2 - Piezoelectric element, liquid discharge head using the same, and recording apparatus - Google Patents

Description

  The present invention relates to a piezoelectric substrate, a piezoelectric element using the same, a liquid discharge head, and a recording apparatus.

  Conventionally, as a printing head, for example, an inkjet head (liquid ejection head) that performs various types of printing by ejecting liquid onto a recording medium is known. A flow path member having a plurality of liquid ejection holes connecting the inkjet head to the manifold and the plurality of liquid pressurization chambers respectively, and a plurality of individual units provided so as to overlap the plurality of liquid pressurization chambers, respectively. There is known a configuration in which a piezoelectric actuator unit having a plurality of displacement elements including an electrode, a common electrode facing a plurality of individual electrodes, and a piezoelectric ceramic layer sandwiched between them is laminated ( For example, see Patent Document 1.) In this liquid ejection head, liquid pressurizing chambers connected to a plurality of liquid ejection holes are arranged in a matrix, and the displacement element of the piezoelectric actuator unit provided so as to cover it is displaced by deformation of the piezoelectric body. Ink is ejected from each liquid ejection hole, and printing is possible at a resolution of 600 dpi in the main scanning direction.

JP 2008-200902 A

  In the liquid discharge head as described in Patent Document 1, there are problems that the displacement amount of the displacement element is small, the liquid discharge amount is small, and the discharge speed is low.

  Therefore, an object of the present invention is to provide a piezoelectric substrate capable of increasing the amount of displacement, a piezoelectric element using the same, a liquid discharge head, and a recording apparatus.

The piezoelectric element of the present invention includes a piezoelectric substrate in which a plurality of piezoelectric layers and a plurality of electrode layers are alternately stacked, and the first main surface and the second main surface of the piezoelectric substrate. A piezoelectric element including a support member laminated on two principal surface sides, wherein the piezoelectric substrate is disposed on the first principal surface side and includes at least two electrode layers and the two layers. A first piezoelectric portion including the piezoelectric layer sandwiched between the two electrode layers, and at least two electrode layers disposed on the second main surface side and the two electrode layers. A second piezoelectric part including the sandwiched piezoelectric layer, and the second piezoelectric part is disposed so as to surround the first piezoelectric part when the piezoelectric substrate is viewed in plan view. The support member includes an opening, and the opening overlaps the first piezoelectric portion and the second piezoelectric portion. And there is a second overlap region in the outer peripheral portion of the second piezoelectric portion where the second piezoelectric portion and a support plate opening edge that forms the outer periphery of the opening overlap. Features.

  The liquid discharge head according to the present invention includes a plurality of the piezoelectric elements, and the support member includes a plurality of openings on the substrate side, and the plurality of openings each include a plurality of the first and second piezoelectric elements. It is arrange | positioned so that it may overlap with a part, The said supporting member is provided with the several discharge hole respectively connected from the said some opening, It is characterized by the above-mentioned.

  The Kiyoku device of the present invention includes the 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.

According to the piezoelectric element of the present invention, the displacement amount of the piezoelectric element can be increased by the presence of the second overlap region.

(A) is a side view of a recording apparatus including a liquid ejection head according to an embodiment of the present invention, and (b) is a plan view. (A) is a top view of the head main body which is the principal part of the liquid discharge head of FIG. 1, (b) is a top view which remove | excluded the 2nd flow-path member from (a). FIG. 3 is an enlarged plan view of a part of FIG. FIG. 3 is an enlarged plan view of a part of FIG. (A) is a partial longitudinal cross-sectional view along the VV line of FIG. 4, (b) is a partial longitudinal cross-sectional view of the head main body of FIG. 2 (a). (A) is an expanded longitudinal cross-sectional view of the principal part of Fig.5 (a), (b) is a top view of (a). It is a graph showing the relationship between the width W1 of a 1st overlap area | region, and volume displacement amount. (A), (b) is the graph showing the relationship between the width W2 of a 2nd overlap area | region, and volume displacement amount.

  FIG. 1A is a schematic side view of a (color inkjet) printer 1 which is a recording apparatus including a liquid discharge head 2 according to an embodiment of the present invention, and FIG. 1B is a schematic plan view. It is. The printer 1 moves the printing paper P relative to the liquid ejection head 2 by transporting the printing paper P that is a recording medium from the transporting roller 80 a to the transporting roller 80 b. The control unit 88 controls the liquid ejection head 2 based on image and character data, ejects liquid toward the recording medium P, causes droplets to land on the printing paper P, and prints on the printing paper P. Record such as.

  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. As another embodiment of the recording apparatus of the present invention, the operation of moving the liquid ejection head 2 by reciprocating in the direction intersecting the transport direction of the printing paper P, for example, the direction substantially orthogonal, and the printing paper P There is a so-called serial printer that alternately conveys.

  A flat plate (head mounting) frame 70 is fixed to the printer 1 so as to be substantially parallel to the printing paper P. The frame 70 is provided with 20 holes (not shown), and the 20 liquid discharge heads 2 are mounted in the respective hole portions, and the portion of the liquid discharge head 2 that discharges the liquid is the printing paper P. It has come to face. The distance between the liquid ejection head 2 and the printing paper P is, for example, about 0.5 to 20 mm. 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 a long and narrow shape in the direction from the front to the back in FIG. 1A and in the vertical direction in FIG. This long direction is sometimes called the longitudinal direction. Within one head group 72, the three liquid ejection heads 2 are arranged along a direction that intersects the conveyance direction of the printing paper P, for example, a substantially orthogonal direction, and the other two liquid ejection heads 2 are conveyed. Each of the three liquid ejection heads 2 is arranged at a position shifted along the direction. The liquid discharge heads 2 are arranged so that the printable range of each liquid discharge head 2 is connected in the width direction of the print paper P (in the direction intersecting the conveyance direction of the print paper P) or the ends overlap. Thus, printing without gaps in the width direction of the printing paper P is possible.

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

  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 and the number of the head groups 72 can be appropriately changed according to the printing target and printing conditions. For example, the number of head groups 72 may be increased to perform multicolor printing. Also, by arranging a plurality of head groups 72 that print in the same color and printing alternately in the transport direction, the printing speed (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 a direction crossing the transport direction, so that the resolution in the width direction of the print paper P may be increased.

  Further, in addition to printing colored inks, a liquid such as a coating agent may be printed for surface treatment of the printing paper P.

  The printer 1 performs printing on a printing paper P that is a recording medium. The printing paper P is wound around the paper feed roller 80a, passes between the two guide rollers 82a, passes through the lower side of the liquid ejection head 2 mounted on the frame 70, and thereafter It passes between the two conveying rollers 82b and is finally collected by the collecting roller 80b. When printing, the printing paper P is conveyed at a constant speed by rotating the conveyance roller 82 b and printed by the liquid ejection head 2. The collection roller 80b winds up the printing paper P sent out from the conveyance roller 82b. The conveyance speed is, for example, 50 m / min. Each roller may be controlled by the controller 88 or may be manually operated by a person.

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

  In addition, a position sensor, a speed sensor, a temperature sensor, and the like may be attached to the printer 1, and the control unit 88 may control each part of the printer 1 according to the state of each part 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.

  Next, the liquid discharge head 2 according to an embodiment of the present invention will be described. FIG. 2A is a plan view showing a head main body 2a which is a main part of the liquid ejection head 2 shown in FIG. FIG. 2B is a plan view showing a state in which the second flow path member 6 is removed from the head main body 2a. 3 and 4 are enlarged plan views of FIG. 2 (b). FIG. 5A is a longitudinal sectional view taken along the line VV in FIG. 4, and FIG. 5B shows the first main body 2 in the vicinity of the opening 20 a of the first common supply channel 20. 4 is a partial longitudinal sectional view taken along a common supply channel 20. FIG. FIG. 6A is an enlarged longitudinal sectional view of the main part of FIG. 5A, and FIG. 6B is a plan view of FIG. 6A.

  Each figure is drawn as follows for easy understanding of the drawing. In FIGS. 2 to 4 and FIG. 6 (b), a flow path and the like that should be drawn with a broken line below other objects are drawn with a solid line. In FIG. 2A, the flow path in the first flow path member 4 is almost omitted, and only the arrangement of the pressurizing chamber 10 is shown. In FIG. 4, the widths of first and second overlap regions described later are drawn as if they were 0 (zero).

  In addition to the head main body 2a, the liquid discharge head 2 may include a metal casing, a driver IC, a wiring board, and the like. The head main body 2a has a first flow path member 4 as a support member, a second flow path member 6 for supplying a liquid to the first flow path member 4, and a displacement element 50 as a pressure unit. A piezoelectric actuator substrate 40. The head body 2a has a flat plate shape that is long in one direction, and this direction is sometimes referred to as a longitudinal direction.

  The first flow path member 4 constituting the head body 2a has a flat plate shape, and the thickness thereof is about 0.5 to 2 mm. A number of pressurizing chambers 10 are arranged in the plane direction on the pressurizing chamber surface 4-1, which is the first main surface of the first flow path member 4. On the discharge hole surface 4-2 that is the second main surface of the first flow path member 4, a large number of discharge holes 8 through which liquid is discharged are arranged in the plane direction. The discharge hole 8 is connected to the pressurizing chamber 10.

  The first channel member 4 includes a plurality of first common supply channels (hereinafter sometimes referred to as first supply channels) 20 and a plurality of first common recovery channels (hereinafter referred to as first recovery channels). 24 are arranged to extend along the first direction. The first supply channel 20 and the first recovery channel 24 are alternately arranged in the second direction, which is a direction intersecting the first direction.

  The pressurizing chambers 10 are arranged along both sides of the first supply flow path 20, and constitute a total of two pressurizing chamber rows 11 </ b> A, one on each side. The first supply channel 20 and the pressurizing chambers 10 arranged on both sides of the first supply channel 20 are connected via an individual supply channel 12.

  The pressurizing chambers 10 are arranged along both sides of the first recovery flow path 24, and constitute a total of two pressurizing chamber rows 11 </ b> A, one on each side. The first recovery flow path 22 and the pressurizing chambers 10 arranged on both sides of the first recovery flow path 22 are connected via an individual recovery flow path 14 that is an individual recovery flow path.

  With the configuration described above, in the first flow path member 4, the liquid supplied to the first supply flow path 20 flows into the pressurizing chambers 10 arranged along the first supply flow path 20, and a part thereof The other liquid is discharged from the discharge hole 8, and another part of the liquid flows into the first recovery flow path 24 located on the opposite side of the first supply flow path 20 with respect to the pressurizing chamber 10. It is discharged from the one flow path member 4 to the outside.

  By arranging the first recovery channel 24 on both sides of the first supply channel 20 and the first supply channel 20 on both sides of the first recovery channel 24, one pressurizing chamber row 11A is provided. One first supply flow path 20 and one first recovery flow path 24 are connected, and another first supply flow path 20 and another first recovery flow path with respect to another pressurization chamber row 11A. Compared with the case where 24 is connected, the number of the 1st supply flow paths 20 and the 1st collection | recovery flow paths 24 can be made into about a half, and it is preferable. Since the number of first supply channels 20 and first recovery channels 24 is small, the number of pressurizing chambers 10 is increased to increase the resolution, or the first supply channel 20 and the first recovery channel 24 are made thicker. Thus, the difference in ejection characteristics from the ejection holes 8 can be reduced, and the size of the head body 2a in the planar direction can be reduced.

  The pressure applied to the portion of the individual supply channel 12 connected to the first supply channel 20 on the first supply channel 20 side is affected by the pressure loss, and the pressure of the individual supply channel 12 in the first supply channel 20 is reduced. It depends on the position. The pressure applied to the part on the individual recovery channel 14 side connected to the first recovery channel 24 varies depending on the position of the individual recovery channel 14 in the first recovery channel 24 due to the effect of pressure loss. If the opening 20a to the outside of the first supply channel 20 is arranged at one end in the first direction and the opening 24a to the outside of the first recovery channel 24 is arranged at the other end in the first direction. The pressure difference due to the arrangement of the individual supply flow paths 12 and the individual recovery flow paths 14 is canceled out, and the pressure difference applied to the discharge holes 8 can be reduced. Note that both the opening 20a of the first supply channel 20 and the opening 24a of the first recovery channel 24 open to the pressurizing chamber surface 4-1.

  In the state of not discharging, a liquid meniscus is held in the discharge hole 8. Since the pressure of the liquid in the discharge hole 8 is a negative pressure (a state where the liquid is about to be drawn into the first flow path member 4), the meniscus can be held in balance with the surface tension of the liquid. If the positive pressure increases, the liquid overflows, and if the negative pressure increases, the liquid is drawn into the first flow path member 4, and the liquid cannot be discharged. For this reason, it is necessary to prevent the difference in the pressure of the liquid in the discharge hole 8 from becoming too large when the liquid flows from the first supply flow path 20 to the first recovery flow path 24.

  The pressurizing chamber 10 is arranged to face the pressurizing chamber surface 4-1, and the pressurizing chamber main body 10a that receives the pressure from the displacement element 50 and the discharge hole surface 4- from below the pressurizing chamber main body 10a. 2 is a hollow region including a descender 10b, which is a partial flow path connected to the discharge hole 8 opened in FIG. The pressurizing chamber body 10a has a right circular cylinder shape, and the planar shape is a circular shape. Since the planar shape is circular, the displacement amount when the displacement element 50 is deformed with the same force and the volume change of the pressurizing chamber 10 caused by the displacement can be increased. The descender 10b has a right circular cylinder shape whose diameter is smaller than that of the pressurizing chamber body 10a, and its planar shape is a circular shape. Moreover, the descender 10b is arrange | positioned in the position stored in the pressurization chamber main body 10a, when it sees from the pressurization chamber surface 4-1. The descender 10b may have a conical shape or a trapezoidal conical shape whose sectional area decreases toward the discharge hole 8 side. Since the planar shape of the descender 10b is smaller than that of the pressurizing chamber main body 10a, the widths of the first supply channel 20 and the first recovery channel 24 can be increased correspondingly, and the above-described pressure loss difference can be decreased.

The plurality of pressurizing chambers 10 constitute a plurality of pressurizing chamber rows 11A along the first direction, and a plurality of pressurizing chamber rows 11B along the second direction that intersects the first direction. Is configured. Each discharge hole 8 is located at the center of the corresponding pressurizing chamber 10. Similarly to the pressurizing chamber 1, the plurality of discharge holes 8 constitute a plurality of discharge hole rows 9A along the first direction and a plurality of discharge hole rows 9B along the second direction. Yes.

  In the present embodiment, there are 50 first supply channels 20 and 51 second supply channels 24, and there are 100 pressurizing chamber rows 11A and discharge hole rows 9A. One pressurization chamber row 11A includes 16 pressurization chambers 10, and one discharge hole row 9A includes 16 discharge holes 8. That is, the pressurizing chamber row 11B has 16 rows, and the discharge hole row 9B has 16 rows.

  In the adjacent pressurizing chamber row 11A, it is preferable that the pressurizing chambers 10 are shifted in the first direction and arranged in a staggered manner because the distance between the pressurizing chambers 10 belonging to the adjacent pressurizing chamber row 11A can be increased. In that case, the pressurizing chamber row 11B has 32 rows, and the discharge hole row 9B has 32 rows.

  The angle formed by the first direction and the second direction (the longitudinal direction of the head body 2a) is deviated from a right angle. For this reason, the ejection holes 8 belonging to the ejection hole array 9A arranged along the first direction are displaced in the second direction by the amount of deviation from the right angle. And since the discharge hole row | line 9A is arrange | positioned along with the 2nd direction, the discharge hole 8 which belongs to the different discharge hole row | line | column 9A is shifted | deviated and arranged in the 2nd direction by that amount. Together, the discharge holes 8 of the first flow path member 4 are arranged at regular intervals in the second direction, so that a predetermined range is filled with pixels formed by the discharged liquid. Can print.

  In FIG. 3, when the discharge holes 8 are projected in a direction orthogonal to the second direction, 32 discharge holes 8 are projected in the range of the virtual straight line R, and the discharge holes 8 are arranged at intervals of 360 dpi in the virtual straight line R. . Accordingly, if the printing paper 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 ejection holes 8 projected in the virtual straight line R belong to all (16) ejection holes 8 belonging to one ejection hole array 9A and to two ejection hole arrays 9A located on both sides of the ejection hole array 9A. Eight half (eight) discharge holes. In each discharge hole row 9B, the discharge holes 8 are arranged at intervals of 22.5 dpi.

  If the discharge holes 8 belonging to one discharge hole row 9A are arranged in a straight line along the first direction, printing can be performed so as to fill the predetermined range as described above. However, in such an arrangement, the influence on the printing accuracy is increased due to the deviation between the second direction and the transport direction that occurs when the liquid ejection head 2 is installed in the printer 1. For this reason, it is preferable that the discharge holes 8 are replaced and arranged between the adjacent discharge hole rows 9A from the arrangement of the discharge holes 8 on the straight line described above. In the present embodiment, the discharge holes 8 are replaced in groups of four. Therefore, in one discharge hole row 9A, four discharge holes 8 are arranged in a straight line from one end side in the first direction, and the following eight discharge holes 8 are arranged side by side. The four subsequent discharge holes 8 are arranged on another straight line that is different from the straight line on which the previous eight discharge holes 8 are arranged.

  The first supply channel 20 and the first recovery channel 24 are straight in a range where the discharge holes 8 are arranged in a straight line, and are shifted in parallel between the discharge holes 8 where the straight lines are shifted. Since there are few such deviations in the first supply channel 20 and the first recovery channel 24, the channel resistance is small. Further, since the portion that is shifted in parallel is arranged at a position that does not overlap with the pressurizing chamber 10, it is possible to reduce the variation in discharge characteristics for each pressurizing chamber 10.

The pressurizing chambers 10 belonging to the pressurizing chamber row 11B located at both ends in the second direction are dummy pressurizing chambers. The first supply channel 20 or the first recovery channel 24 is provided on the end side in the second direction with respect to the dummy pressurizing chamber. If the first recovery flow path 24 is disposed on the center side in the second direction with respect to the dummy pressurizing chamber, the disposed flow path becomes the first supply flow path 20, and the dummy pressurization chamber On the other hand, if the first supply channel 20 is disposed on the center side in the second direction, the first recovery channel 24 is formed. Similarly to the normal pressurizing chamber 10, the dummy pressurizing chamber is connected to the first supply channel 20 via the individual supply channel 12, and is connected to the first recovery channel 24 via the individual recovery channel 14. It is connected.

  The common flow path (either the first common supply flow path 20 or the first common recovery flow path 24) located at the end in the second direction has one row of pressurizing chambers 11A to be supplied or recovered. For this reason, the discharge characteristics of the discharge from the pressurization chambers 10 belonging to the one pressurization chamber array 11 </ b> A may vary with respect to the discharge characteristics from the other pressurization chambers 10. Therefore, the pressurizing chambers 10 belonging to the pressurizing chamber row 11A are dummy pressurizing chambers that are not used for printing. The basic shape of the dummy pressurizing chamber is the same as that of the normal pressurizing chamber 10, and the discharge hole 8 may or may not be disposed on the discharge hole surface 4-2 side.

  As described above, if the pressurizing chamber 10 belonging to the pressurizing chamber row 11A located at both ends in the second direction is a dummy pressurizing chamber, the pressurizing chamber row 11A located second from both ends in the second direction is used. The first supply flow path 20 for supplying the liquid to the pressure chamber 10 to which it belongs supplies the liquid to the two pressure chamber rows 11A in the same manner as the other normal first supply flow paths 20, and the second As with other normal first recovery channels 24, the first recovery channels 24 that recover the liquid in the pressurization chambers 10 belonging to the pressurization chamber column 11A located at the second position from both ends of the direction are added in two rows. Since the liquid in the pressure chamber row 11A is collected, a difference in ejection characteristics is less likely to occur.

  Among the discharge holes 8 belonging to the discharge hole row 9A located second from the end in the second direction, the eight discharge holes 8 close to the end in the second direction do not have an interval in the second direction of 360 dpi. Therefore, the discharge hole 8 is not provided at that position, and the pressurizing chamber 10 at the corresponding position may be a dummy pressurizing chamber.

  The second flow path member 6 is joined to the pressurizing chamber surface 4-1 of the first flow path member 4, and a second common supply flow path (hereinafter referred to as a second flow path) that supplies liquid to the first supply flow path. And a second common recovery channel (hereinafter also referred to as a second recovery channel) 26 for recovering the liquid in the first recovery channel. . The thickness of the second flow path member 6 is thicker than the first flow path member 4 and is about 5 to 30 mm lower.

  The second flow path member 6 is joined in a region where the piezoelectric actuator substrate 40 of the pressure chamber surface 4-1 of the first flow path member 4 is not connected. More specifically, the piezoelectric actuator substrate 40 is joined so as to surround it. By doing in this way, it can suppress that a part of discharged liquid adheres to the piezoelectric actuator board | substrate 40 as mist. In addition, since the first flow path member 4 is fixed on the outer periphery, it is possible to suppress the first flow path member 4 from vibrating due to the driving of the displacement element 50 and causing resonance or the like.

  Further, the second flow path member 6 has a through hole 6c extending vertically. The through hole 6c is passed through a wiring member such as an FPC (Flexible Printed Circuit) that transmits a drive signal for driving the piezoelectric actuator substrate 40. The first flow path member 4 side of the through hole 6c is a widened portion 6ca having a wide width in the short direction, and the wiring member extending from the piezoelectric actuator substrate 40 to both sides in the short direction is widened. It is bent at the portion 6 ca and goes upward, and passes through the through hole 6. In addition, since the convex part of the part which spreads in the wide part 6ca may damage a wiring member, it is preferable to make it R shape.

By disposing the second supply channel 22 in the second channel member 6 that is different from the first channel member 4 and is thicker than the first channel member 4, the cross-sectional area of the second supply channel 22 is increased. Accordingly, a difference in pressure loss due to a difference in position where the second supply channel 22 and the first supply channel 20 are connected can be reduced. The flow resistance of the second supply flow path 22 (more precisely, the flow resistance of the second supply flow path 22 in a range connected to the first supply flow path 20) is equal to that of the first supply flow path 20. It is preferable to make it 1/100 or less.

  By disposing the second recovery flow path 26 in the second flow path member 6 that is different from the first flow path member 4 and thicker than the first flow path member 4, the cross-sectional area of the second recovery flow path 26 is increased. Accordingly, the difference in pressure loss due to the difference in the position where the second recovery channel 26 and the first recovery channel 24 are connected can be reduced. The flow path resistance of the second recovery flow path 26 (more precisely, the flow resistance of the second recovery flow path 26 that is connected to the first recovery flow path 22) is equal to that of the first recovery flow path 24. It is preferable to make it 1/100 or less.

  The second supply channel 22 is arranged at one end of the second channel member 6 in the short direction, the second recovery channel 26 is arranged at the other end of the second channel member 6 in the short direction, Each flow path is directed to the first flow path member 4 side so as to be connected to the first supply flow path 20 and the first recovery flow path 24, respectively. By doing so, the cross-sectional areas of the second supply flow path 22 and the second recovery flow path 26 can be increased (that is, the flow path resistance can be reduced), and the first flow path member 4 can be formed by the second flow path member 6. The outer periphery of the wiring member can be fixed to increase the rigidity, and a through hole 6c through which the wiring member passes can be provided.

  The second flow path member 6 is configured by laminating plates 6a and 6b of the second flow path member. On the upper surface of the plate 6b, a groove serving as a second supply channel body 22a, which is a portion of the second supply channel 22 extending in the second direction and having a low channel resistance, and a second recovery channel 26 A groove serving as a second supply flow path body 26a, which is a portion having a low flow resistance extending in the second direction, is disposed.

  A plurality of supply connection channels 22b extend downward (in the direction of the first channel member 4) from the groove serving as the second supply channel main body 22a, and are opened on the pressurizing chamber surface 4-1. It is connected to the opening 20a of the first supply channel. Each supply connection flow path 22b is partitioned by a partition 6ba (that is, the first supply flow path 20 side of the supply connection flow path 22b is branched). Thereby, the rigidity of the connection between the second flow path member 6 and the first flow path member 4 can be increased. Furthermore, in the second direction, the length of the partition 6ba is longer than the length of the supply connection channel 22b, so that the rigidity of connection between the second channel member 6 and the first channel member 4 is further increased. it can.

  A plurality of recovery connection flow paths 26b extend downward (in the direction of the first flow path member 4) from the groove serving as the second recovery flow path body 26a, and are opened on the pressure chamber surface 4-1. Connected to the opening 24a of the first recovery channel. Each recovery connection channel 26b is partitioned by a partition 6bb (that is, the first recovery channel 24 side of the recovery connection channel 26b is branched). Thereby, the rigidity of the connection between the second flow path member 6 and the first flow path member 4 can be increased. Furthermore, in the second direction, the length of the partition 6bb is longer than the length of the recovery continuation channel 26b, so that the rigidity of the connection between the second channel member 6 and the first channel member 4 is further increased. it can.

  The plate 6 a is provided with openings 22 c and 22 d at both ends in the second direction of the second supply flow path 22. The plate 6 a is provided with openings 26 c and 26 d at both ends in the second direction of the second recovery flow path 26. When supplying the liquid to the liquid discharge head 2 that does not contain liquid, the liquid is supplied from one opening (for example, the opening 22c) so that the liquid in the second supply flow path 22 is easily discharged to the outside. While supplying the liquid to the flow path member 4 and discharging the air and the overflowing liquid from another opening (for example, 22d), it is possible to make it difficult for the gas to enter the first flow path member 4. Similarly, the second recovery flow channel 26 may be discharged from one opening (for example, the opening 26c) and from the other opening (for example, the opening 26d).

When printing, there are several ways to supply and recover the liquid. One is that all of the liquid supplied to the second supply flow path 22 enters the first flow path member 4 and further the second recovery flow path 26.
It enters and is discharged outside. At this time, no liquid is supplied to the second recovery flow path 26 from the outside. In this case, the liquid is supplied from the two openings 22c and 22d and recovered from the two openings 26c and 26d, the liquid is supplied from one of the openings 22c and 22d, the other is closed, and the opening 26c is closed. 26d, there is a method in which the liquid is recovered from one of them and the other is closed, and there is a method in which the combination of the two is reversed. In order to reduce the pressure difference due to the pressure loss, it is preferable to supply from two openings and collect from the two openings, but the connection of the tube for supplying and discharging the liquid makes the pressure control complicated. Supplying from one opening and collecting from one opening simplifies connection and control of pressure. In that case, it is preferable that the supply and the recovery are performed in pairs with the openings at positions opposite to each other in the second direction because the influence of the pressure loss is offset. Specifically, it may be supplied from the opening 22c and recovered from the opening 26d, or supplied from the opening 22d and recovered from the opening 26c.

  Another method of supplying and discharging is to supply the liquid from one opening (for example, 22c) of the second supply flow path 22, collect the liquid from the other opening (for example, 22d), and For example, liquid is supplied from 26d) and recovered from the other opening (for example, 26c). If the pressure of each supply / discharge is adjusted so that the pressure of the second supply flow path 22 becomes higher than the pressure of the second recovery flow path 26, the liquid flows through the first flow path member 4. . In this way, the difference in pressure applied to the meniscus of each discharge hole 8 is the smallest.

  The above two methods may be combined to supply / discharge the second supply flow path 22 and only recover from the second recovery flow path 26. Conversely, only the second supply channel 22 may be supplied and the second recovery channel 26 may be supplied and discharged.

  Furthermore, the relationship between supply and recovery described above may be reversed. For example, the liquid may be supplied from both of the two openings 26 c and 26 d of the second recovery flow path 26 and the liquid may be recovered from both of the two openings 22 c and 22 d of the second recovery flow path 22.

  A damper may be provided in the second supply channel 22 and the second recovery channel 26 so that the supply or discharge of the liquid is stable with respect to fluctuations in the discharge amount of the liquid. Further, by providing a filter in the second supply flow path 22 and the second recovery flow path 26, foreign substances and bubbles may be difficult to enter the first flow path member 4.

  A piezoelectric actuator substrate 40 including a displacement element 50 is bonded to the pressurizing chamber surface 4-1 that is the upper surface of the first flow path member 4 so that each displacement element 50 is positioned on the pressurizing chamber 10. Has been placed. 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 of each pressurizing chamber 10 is closed by joining the piezoelectric actuator substrate 40 to the pressurizing 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. The piezoelectric actuator substrate 40 is connected to a signal transmission unit such as an FPC for supplying a signal to each displacement element 50. The second flow path member 6 has a through hole 6c penetrating vertically at the center, and the signal transmission unit is electrically connected to the control unit 88 through the through hole 6c. The signal transmission unit has a shape extending in the short direction from one long side end of the piezoelectric actuator substrate 40 toward the other long side end, and the wiring disposed in the signal transmission unit extends along the short direction. Extending and arranging in the longitudinal direction is preferable because the distance between the wirings can be easily obtained.

  First individual electrodes 44 are arranged at positions facing the pressurizing chambers 10 on the first main surface 40-1, which is the upper surface of the piezoelectric actuator substrate 40. In addition, second individual electrodes 45 are arranged at positions facing the pressurizing chambers 10 on the second main surface 40-2, which is the lower surface of the piezoelectric actuator substrate 40, respectively. These electrodes will be described in detail later.

  The flow path member 4 has a laminated structure in which a plurality of plates are laminated. These plates are a cavity plate 4a, a supply plate 4b, manifold plates 4c to 4e, a recovery plate 4f, and a nozzle plate 4g in order from the upper surface of the flow path member 4. Many holes and grooves are formed in these plates. For example, the holes and grooves can be formed by etching each plate made of metal. Since the thickness of each plate is about 10 to 300 μm, the formation accuracy of the holes to be formed can be increased. The manifold plates 4c to 4e have the same shape and may be constituted by one plate, but are constituted by three plates in order to form holes with high accuracy. The plates are aligned and stacked such that these holes communicate with each other to form a flow path such as the manifold 5.

  A pressurizing chamber body 10a is opened on the pressurizing chamber surface 4-1 of the flat channel member 4, and the piezoelectric actuator substrate 40 is joined thereto. The pressurizing chamber surface 4-1 has an opening 20 a for supplying liquid to the first supply channel 20 and an opening 24 a for recovering liquid from the first recovery channel 24. A discharge hole 8 is opened in the discharge hole surface 4-2 on the opposite side of the pressure chamber surface 4-1 of the flow path member 4.

  As a structure for discharging the liquid, there are a pressurizing chamber 10 and a discharge hole 8. The pressurizing chamber 10 includes a pressurizing chamber main body 10a facing the displacement element 50 and a descender 10b having a smaller sectional area than the pressurizing chamber main body 10a. The pressurizing chamber main body 10a is formed in the cavity plate 4a, and the descender 10b is overlapped with holes formed in the plates 4b to 4f, and further blocked by the nozzle plate 4g (parts other than the discharge holes 8). It is made up of.

  An individual supply channel 12 is connected to the pressurizing chamber body 10 a, and the individual supply channel 12 is connected to the first supply channel 20. The individual supply channel 12 is a circular hole penetrating the supply plate 4b, and the liquid flows in the vertical direction. The first supply flow path 20 is formed by overlapping holes formed in the plates 4c to 4h, and is further closed by the supply plate 4b on the upper side and the nozzle plate 4g on the lower side.

  The individual recovery flow path 14 is connected to the descender 10 b, and the individual recovery flow path 14 is connected to the first recovery flow path 24. The individual recovery channel 14 is a through groove that passes through the recovery plate 4f, and the liquid flows along the groove. The first recovery flow path 24 is formed by overlapping holes formed in the plates 4c to 4h, and is further closed by the supply plate 4b on the upper side and the nozzle plate 4g on the lower side.

  Regarding the liquid flow, the liquid supplied to the second supply flow path 22 passes through the first supply flow path 20 and the individual supply flow path 12 into the pressurizing chamber 10 in order, and a part of the liquid is discharged. It is discharged from the hole 8. The liquid that has not been discharged passes through the individual recovery flow path 14, enters the first recovery flow path 24, then enters the second recovery flow path, and is discharged outside the head body 2.

The piezoelectric actuator substrate 40 has a laminated structure composed of two piezoelectric ceramic layers 40a and 40b that 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 between the piezoelectric ceramic layer 40a and the piezoelectric ceramic layer 40b is set to 3: 7 to 7: 3, preferably 4: 6 to 6: 4. 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 actuator substrate 40 includes a common electrode 42 made of a metal material such as Ag—Pd, and a first individual electrode 44 and a second individual electrode 45 made of a metal material such as Au. The thickness of the common electrode 42 is about 2 μm, and the thickness of the first individual electrode 44 and the second individual electrode 45 is about 1 μm.

  The first individual electrode 44 is disposed on the first main surface 40-1 that is the upper surface of the piezoelectric actuator substrate 40. The first individual electrode 44 has a shape that is slightly smaller than the pressurizing chamber main body 10a and has a shape substantially similar to the pressurizing chamber main body 10a, and the first individual electrode main body 44a. And a first extraction electrode 44b that is extracted. A connection electrode 46 is formed at a portion of one end of the first extraction electrode 44 b that is extracted outside the region facing the pressurizing chamber 10. 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. Further, the connection electrode 46 is electrically joined to an electrode provided in the signal transmission unit 60.

  The second individual electrode 45 is disposed on the second main surface 40-2 which is the lower surface of the piezoelectric actuator substrate 40. The second individual electrode 45 includes a second individual electrode main body 45a having a ring shape in plan view, and a second extraction electrode 45b drawn from the second individual electrode main body 45a. The second individual electrode body 45a is disposed so as to surround the first individual electrode body 44a. It is not always necessary to completely surround it, and 75% or more of the first individual electrode main body 44a may be surrounded as viewed from the center of gravity of the area. It is more preferable that 90% or more is surrounded, and it is particularly preferable that it is completely surrounded. In FIG. 6B, the second individual extraction electrode 45b and the first extraction electrode 44b are overlapped and shown at the same position.

  The 1st extraction electrode 44b and the 2nd extraction electrode 45b are electrically connected by the penetration conductor 48 which has penetrated the piezoelectric ceramic layers 40a and 40b. The common electrode 42 is not formed in a portion through which the through conductor 48 penetrates.

  A common electrode surface electrode (not shown) is formed on the upper surface of the piezoelectric actuator substrate 40. The common electrode surface electrode and the common electrode 42 are electrically connected through a through conductor (not shown) disposed in the piezoelectric ceramic layer 40a.

  Although details will be described later, a drive signal is supplied from the control unit 88 to the first individual electrode 44 and the second individual electrode 45 through a signal transmission unit. The drive signal is supplied in a constant cycle in synchronization with the conveyance speed of the print medium P.

  The common electrode 42 is formed over almost the entire surface in the region between the piezoelectric ceramic layer 40a and the piezoelectric ceramic layer 40b. That is, the common electrode 42 extends so as to cover all the pressurizing chambers 10 in the region facing the piezoelectric actuator substrate 40. The common electrode 42 is connected to the surface electrode for the common electrode formed on the piezoelectric ceramic layer 40a so as to avoid the electrode group including the first individual electrodes through a via hole formed through the piezoelectric ceramic layer 40a. Are grounded and held at ground potential. The common electrode surface electrode is directly or indirectly connected to the controller 88 in the same manner as the multiple first individual electrodes.

  The portion of the piezoelectric ceramic layer 40a sandwiched between the first individual electrode body 44a and the common electrode 42 is polarized in the thickness direction, and deforms when a voltage is applied to the first individual electrode body 44a. The first individual electrode main body 44a and the common electrode 42 that are arranged to face each other and the piezoelectric ceramic layer 40a sandwiched between them are referred to as a first piezoelectric portion A.

The portion of the piezoelectric ceramic layer 40b sandwiched between the second individual electrode body 45a and the common electrode 42 is polarized in the thickness direction, and deforms when a voltage is applied to the second individual electrode body 45a. The second individual electrode main body 45a and the common electrode 42 which are disposed to face each other and the piezoelectric ceramic layer 40b sandwiched between them are referred to as a second piezoelectric portion B.

  The polarization direction of the second piezoelectric part B is reversed to the polarization direction of the first piezoelectric part A (the arrow in FIG. 6A represents the polarization direction), and the first individual electrode body 44a and the second individual electrode body Apply the same voltage to 45a. If an electric field is applied in the same direction as the polarization direction, the first piezoelectric part A and the second piezoelectric part B function as active parts that are distorted by the piezoelectric effect and contract in the planar direction. The piezoelectric ceramic layers 40a and 40b in the other parts of the displacement element 50 are inactive portions that do not generate an electric field directly even when a voltage is applied to the first individual electrode main body 44a and the second individual electrode main body 45a. Without trying to regulate the deformation of the active part. As a result, the displacement element 50 is displaced toward the pressurizing chamber 10 side.

  The polarization direction of the second piezoelectric part B and the polarization direction of the first piezoelectric part A may be set in the same direction, and opposite voltages may be applied to the first individual electrode body 44a and the second individual electrode body 45a. . However, it is preferable to reverse the polarization direction because the control is simpler when one voltage is applied.

  In order to be able to change whether to apply a voltage for each second individual electrode 45, for example, the piezoelectric actuator substrate 40 and the flow path member 4 may be insulated with an adhesive. In addition, the same voltage is applied to all the second individual electrode bodies 45a every driving, that is, the voltage is applied only to the first piezoelectric part A of the displacement element 50 that piezoelectrically deforms and discharges all the second piezoelectric parts B. You may make it carry out piezoelectric deformation. At this time, the drive signal is such that ejection is not caused only by the deformation of the second piezoelectric portion B, but is ejected when both the second piezoelectric portion B and the first piezoelectric portion A are deformed. In this way, it is possible to easily control the voltage applied to the second individual electrode body 45a.

  In the present embodiment, the first piezoelectric part A and the second piezoelectric part B are composed of two electrode layers and one piezoelectric layer (piezoelectric ceramic layer) sandwiched between them. The electrode layers and the plurality of piezoelectric layers may be alternately stacked.

  Next, the liquid discharge operation will be described. The displacement element 50 is driven (displaced) by a drive signal supplied to the first individual electrode 44 and the second individual electrode 45 through a driver IC or the like under the control of the control unit 88. In the present embodiment, liquid can be ejected by various driving signals. Here, a so-called strike driving method will be described.

  The first individual electrode 44 and the second individual electrode 45 are set to a potential higher than the common electrode 42 (hereinafter referred to as a high potential) in advance, and the first individual electrode 44 and the second individual electrode 45 are connected to the common electrode every time there is a discharge request. 42 is once set to the same potential (hereinafter referred to as a low potential), and then set to a high potential again at a predetermined timing. Accordingly, at the timing when the first individual electrode 44 and the second individual electrode 45 become a low potential, the piezoelectric ceramic layers 40a and 40b return (begin) to the original (flat) shape, and the volume of the pressurizing chamber 10 is initially set. Increased compared to the state (state where the potentials of both electrodes are different). As a result, a negative pressure is applied to the liquid in the pressurizing chamber 10. Then, the liquid in the pressurizing chamber 10 starts to vibrate with the natural vibration period. Specifically, first, the volume of the pressurizing chamber 10 begins to increase, and the negative pressure gradually decreases. Next, the volume of the pressurizing chamber 10 becomes maximum and the pressure becomes almost zero. Next, the volume of the pressurizing chamber 10 begins to decrease, and the pressure increases. Thereafter, the first individual electrode 44 and the second individual electrode 45 are set to a high potential at a timing when the pressure becomes substantially maximum. Then, the first applied vibration overlaps with the next applied vibration, and a larger pressure is applied to the liquid. This pressure propagates through the descender and discharges the liquid from the discharge hole 8.

That is, a droplet can be ejected by supplying to the first individual electrode 44 and the second individual electrode 45 a pulse driving signal that is set to a low potential for a certain period of time with reference to the high potential. If this pulse width is AL (Acoustic Length), which is half the natural vibration period of the liquid in the pressurized chamber 10,
In principle, the discharge speed and discharge amount of the liquid can be maximized. The natural vibration period of the liquid in the pressurizing chamber 10 is greatly influenced by the physical properties of the liquid and the shape of the pressurizing chamber 10, but besides that, the physical properties of the piezoelectric actuator substrate 40 and the flow path connected to the pressurizing chamber 10 Also affected by the characteristics of.

  Note that the pulse width is actually set to a value of about 0.5 AL to 1.5 AL because there are other factors to consider, such as combining the ejected droplets into one. Further, since the discharge amount can be reduced by setting the pulse width to a value outside of AL, the pulse width is set to a value outside of AL in order to reduce the discharge amount.

  In the present embodiment, when the piezoelectric actuator substrate 40 is viewed in plan, the first overlap region where the first piezoelectric portion A and the second piezoelectric portion B overlap, and the second piezoelectric portion B and the pressurizing chamber 10 are formed. The amount of displacement is large due to the presence of the second overlap region where the support plate opening edge C constituting the outer periphery of the opening overlaps.

  First, the basic configuration of the displacement element 50 will be described. The displacement element 50 faces the opening (pressurization chamber) 10 of the support member (flow path member) 4, and the position of the outer side of the displacement element 50 is defined by the opening edge C constituting the outer periphery of the opening 10. It is regulated. The first piezoelectric portion A contracts in the planar direction when a voltage is applied, and the size in the planar direction is smaller than the piezoelectric ceramic layer 40b on which the first piezoelectric portion A is laminated. Bend. The second piezoelectric portion B contracts in the planar direction when a voltage is applied, and the size in the planar direction is smaller than the piezoelectric ceramic layer 40a on which the second piezoelectric portion B is laminated. It becomes a convex shape. Since the position of the outside of the second piezoelectric portion B is regulated by the opening edge portion C, the inside of the second piezoelectric portion B is curved so as to push the first piezoelectric portion A toward the opening 10 side. The bending of the first piezoelectric part A and the second piezoelectric part B is combined, and the displacement element 50 is displaced.

  Although the planar shape of the opening 10 is arbitrary, it is basically a convex shape having no recess. Specifically, a circular shape, an elliptical shape, a convex polygonal shape, or the like. In order to increase the amount of displacement, a shape close to a circular shape is preferable, and in terms of the amount of displacement, a circular shape is optimal.

  The first piezoelectric part A is located substantially at the center of the opening 10 (the center of gravity of the area of the opening 10 is in the first piezoelectric part A), and the area of the first piezoelectric part A is 50 with respect to the area of the opening 10. If it is% to 70%, the amount of displacement can be increased. The area ratio is particularly preferably 55% to 65%.

  Next, the first overlap area will be described. The first overlap region is a region where the first piezoelectric part A and the second piezoelectric part B overlap in the outer peripheral part of the first piezoelectric part A. The portion where the first extraction electrode 45b and the common electrode 42 overlap is not included in the first piezoelectric portion A and is not included in the first overlap region.

  The first overlap region is arranged so as to surround the first piezoelectric part A. It is not always necessary to completely surround it, and 75% or more of the first individual electrode main body 44a may be surrounded as viewed from the center of gravity of the area. It is more preferable that 90% or more is surrounded, and it is particularly preferable that it is completely surrounded. Further, the first overlap region is designed so that the first piezoelectric portion A and the first piezoelectric portion B, which are arranged apart from each other by design, do not overlap and overlap.

When the first overlap region exists, the amount of displacement increases. This is considered to be due to the following reasons. Since the first overlap region is an annular region surrounding the first piezoelectric portion A, when the first overlap region contracts in the plane direction, a force acts to reduce the diameter of the ring. This compresses the first piezoelectric part A from the outside, and reduces the size of the first piezoelectric part A in the planar direction. If it does so, the curve of the 1st piezoelectric part A will become large and will be displaced to the opening 10 side more.

  However, if the area of the first overlap region becomes too large, the amount of displacement is conversely reduced. The reason is that the area of the first overlap region is increased, and accordingly, the length of the opening 10 of the displacement element 50 is shortened, so that the influence is increased. It is done. Therefore, the (average) width W1 [μm] of the first overlap region is set to 6% or less of the diameter of a circle having the same area as the area of the first piezoelectric part A.

  FIG. 7 shows the width W1 of the first overlap region and the volume displacement amount (addition that changes depending on the displacement of the displacement element 50) obtained from the result of the simulation of the displacement element 50 shown in FIGS. 6 (a) and 6 (b). It is a graph of a relationship with the volume of the pressure chamber.

  In the simulation, the support member 4 has a Young's modulus of 200 GPa, a thickness of 50 μm, and the diameter of the opening 10 is 1 mm. The piezoelectric ceramic layers 40a and 40b have a Young's modulus of 80 GPa, the thicknesses of each are 22 μm, and the thickness of the piezoelectric actuator substrate 40 ( 45 μm (from the upper surface of the piezoelectric ceramic layer 40 a to the lower surface of the piezoelectric ceramic layer 40 b) (that is, the thickness of the common electrode 42 is 1 μm), the diameter of the first piezoelectric portion A is 775 μm (thereby, the area of the first piezoelectric portion A is The width W1 [μm] of the first overlap region is changed. Here, the second overlap region described later does not exist (W2 = 0 μm). However, the simulation was performed without the first extraction electrode 44b and the second extraction electrode. In the graph, when there is no first overlap region, for convenience, it is assumed that W1 is negative for the distance between the first piezoelectric part A and the second piezoelectric part B.

  As W1 increases, the volume displacement increases. From the graph, the volume displacement increases in the range of 0 μm <W1 ≦ 50 μm with respect to the volume displacement when W1 is 0 μm. This can be expressed as a ratio to the diameter of the first piezoelectric part A, which is greater than 0% and 6.4% or less. The width of the first overlap region is preferably 1% to 5%, more preferably 2% to 4%, when the volume displacement is maximized in the vicinity of W1 = 20 μm and expressed as a ratio to the diameter of the first piezoelectric part A. % Is particularly preferred.

  As for the range of W1 in which the volume displacement can be increased, even if the size changes in the thickness direction and the plane direction, the ratio of mutual influences does not change, so it can be expressed as a ratio with the diameter of the first piezoelectric part A. For example, the above-mentioned range is considered regardless of the shape and size of the object. This was confirmed by simulation.

  Next, the second overlap area will be described. The second overlap region is a region where the second piezoelectric portion B and the support plate opening edge portion C overlap in the outer peripheral portion of the second piezoelectric portion B.

  The second overlap region is arranged so as to surround the second piezoelectric part B. It is not always necessary to completely enclose, and 75% or more of the second individual electrode main body 45a may be enclosed as viewed from the center of gravity of the area. It is more preferable that 90% or more is surrounded, and it is particularly preferable that it is completely surrounded. Further, the second overlap region is designed so that the second piezoelectric portion B and the support plate opening edge portion C, which are arranged apart from each other in design, are not overlapped but overlapped.

When the second overlap region exists, the amount of displacement increases. This may be due to the following reasons. In the second overlap region, the second piezoelectric portion B contracts in the plane direction, so that the piezoelectric actuator substrate 40 is deformed so as to be bent toward the opening 10 on the support plate opening edge C, and the upper portion of the opening 10 Since the entire piezoelectric actuator substrate 40 is deformed so as to be pushed toward the opening 10, the amount of displacement increases. In addition, as described in the first overlap region, there is a possibility that an effect caused by a decrease in the diameter of the annular second overlap region may be added. When the width of the second overlap region is increased, unlike the case of the first overlap region, the amount of displacement is not reduced compared to the case where there is no second overlap region. This is a region above the portion where the second overlap region is joined to the support member 4, and the width of the second piezoelectric portion B of the second overlap region is increased, so that the piezoelectric actuator substrate on the opening 10 Even if it tries to work so as to extend 40 (so that the amount of displacement is reduced as a result), the movement is restricted by the support member 4, so the piezoelectric actuator substrate 40 is bent on the support plate opening edge C. It is thought that the state where the influence is larger is maintained.

  FIGS. 8A and 8B are the results of evaluating the relationship between the width W2 [μm] of the second overlap region and the volume displacement amount by simulation, as in the case of evaluating the first overlap region. . Parameters different from the evaluation of the first overlap region are as follows. There is no first overlap region (W1 = 0 μm). In the graph of FIG. 8A, the diameter of the opening 10 is set to three types of 0.5 mm, 1 mm, and 2 mm, and the diameter of the first piezoelectric portion A is set to 60% of the area of the opening 10, respectively. In the graph of FIG. 8B, the thickness of the piezoelectric actuator substrate is 30 μm, 45 μm, and 90 μm. In addition, since the volume displacement amount is greatly different in each model, the graph is plotted by normalizing by dividing by the maximum value of each volume displacement amount.

  From FIG. 8A, it can be seen that the peak of the volume displacement amount has W2 in the range of 50 to 100 μm and is not significantly affected by the size of the opening 10. It can also be seen that the volume displacement is almost constant when W2 is 300 μm or more. The volume displacement amount at this time is larger than the volume displacement amount when there is no second overlap region, that is, when W2 = 0 μm, and there is an effect of increasing the volume displacement amount even when the second overlap region is large. I understand.

  From FIG. 8B, the value of W2 that is the peak of the volume displacement amount increases as the thickness of the piezoelectric actuator substrate 40 increases. As the thickness of the piezoelectric actuator substrate 40 increases, a force is required to bend the piezoelectric actuator substrate 40 toward the opening 10 on the support plate opening edge C, so that the volume displacement peak. It is considered that the value of W2 is almost proportional to the thickness of the piezoelectric actuator substrate 40.

  From the above results, the displacement amount can be further increased by setting W2 to be equal to or greater than the thickness of the piezoelectric actuator substrate 40. More specifically, assuming that the improvement of the displacement amount when the displacement amount of W2 is the maximum with respect to the case where W2 = 0 μm is 100%, the above range is an improvement of 40% or more. Furthermore, if W2 is 4 times or less the thickness of the piezoelectric actuator substrate 40, the value of W2 is large, and the displacement can be made larger than the region where the displacement is constant.

  If both the first overlap region and the second overlap region exist, the amount of displacement can be increased. In addition, it is thought that it will become the same tendency as the above-mentioned if both a 1st overlap area | region and a 2nd overlap area | region use a general thing as a piezoelectric material, and use a common metal as the supporting member 4. FIG.

DESCRIPTION OF SYMBOLS 1 ... Printer 2 ... Liquid discharge head 2a ... Head main body 4 ... (1st) Channel member, support member 4a-g ... (1st channel member) plate 4-1 ... Pressurizing chamber surface 4-2 ... Discharge hole surface 6 ... Second flow path member 6a, 6b ... (second flow path member) plate 6ba, 6bb ... Partition 6c -Through hole 6ca (widening part of second flow path member) 8: Widened portion of through hole 8 ... Discharge hole 9A ... Discharge hole array 9B ... Discharge hole row 10 ... Pressurizing chamber 10a ...・ Pressure chamber body, opening 10b ... descender (partial flow path)
11A ... Pressurization chamber row 11B ... Pressurization chamber row 12 ... Individual supply flow channel 14 ... Individual recovery flow channel 20 ... First (common) supply flow channel 20a ... (first) Opening 22 (1 common supply flow path) 22 ... 2nd (common) supply flow path 22a ... 2nd common supply flow path body 22b ... Supply connection flow path 22c, 22d ... (2nd common supply) Opening of channel 24... First (common) recovery channel 24 a... (Opening of first common recovery channel) 26... Second (common) recovery channel 26 a. Recovery channel body 26b ... Recovery connection channel 26ca6d ... (second common recovery channel) opening 40 ... Piezoelectric actuator substrate 40a ... Piezoelectric ceramic layer 40b ... Piezoelectric ceramic layer 40-1 ... First main surface 40-2 ... Second main surface 42 ... Common electrode 44 ... First individual power Electrode 44a ... first individual electrode body 44b ... first extraction electrode 45 ... second individual electrode 45a ... second individual electrode body 45b ... second extraction electrode 46 ... connection electrode 48 ... Penetration electrode 50 ... Displacement element (pressure part)
60 ... Signal transmission unit 70 ... (head mounting) frame 72 ... head group 80a ... feed roller 80b ... collection roller 82a ... guide roller 82b ... conveying roller 88 ... -Control part A ... 1st piezoelectric part B ... 2nd piezoelectric part C ... Opening edge part (of support member) P ... Printing paper

Claims (6)

A piezoelectric substrate in which a plurality of piezoelectric layers and a plurality of electrode layers are alternately stacked, and a first main surface and a second main surface of the piezoelectric substrate are stacked on the second main surface side. A piezoelectric element including a supporting member,
The piezoelectric substrate is
A first piezoelectric part that is disposed on the first main surface side and includes at least two electrode layers and the piezoelectric layer sandwiched between the two electrode layers;
A second piezoelectric portion including at least two electrode layers disposed on the second main surface side and the piezoelectric layer sandwiched between the two electrode layers;
When the piezoelectric substrate is viewed in plan view,
The second piezoelectric part is disposed so as to surround the first piezoelectric part,
The support member includes an opening, and the opening is disposed so as to overlap the first piezoelectric part and the second piezoelectric part,
In the outer peripheral portion of the second piezoelectric portion, there is a second overlap region in which the second piezoelectric portion and a support plate opening edge portion constituting the outer periphery of the opening are overlapped. . The width of the second overlap area, the piezoelectric element according to claim 1, characterized in that at least the thickness of the piezoelectric substrate. 3. The piezoelectric element according to claim 2 , wherein the width of the second overlap region is not more than four times the thickness of the piezoelectric substrate. When the piezoelectric substrate is viewed in plan view,
In the outer periphery of the first piezoelectric portion, there is a first overlap region where the first piezoelectric portion and the second piezoelectric portion overlap, and the width of the first overlap region is the first overlap region. The piezoelectric element according to any one of claims 1 to 3 , wherein the diameter is 6% or less of a diameter of a circle having the same area as the area of the piezoelectric portion. Claim 1 has a plurality of piezoelectric elements according to any one of 4, the support member comprises a plurality of openings on the substrate side, an aperture of the plurality of the plurality of the first and second 2. A liquid ejection head, wherein the liquid ejection head is disposed so as to overlap with the two piezoelectric portions, and the support member includes a plurality of ejection holes respectively connected from the plurality of openings. A recording apparatus comprising: the liquid discharge head according to claim 5; a transport unit that transports a recording medium to the liquid discharge head; and a control unit that controls the liquid discharge head.

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