JP2010260295A - Liquid ejecting head and liquid ejecting apparatus - Google Patents

Abstract

A liquid ejecting head and a liquid ejecting apparatus capable of improving liquid ejecting characteristics by suppressing a decrease in displacement characteristics of a piezoelectric element and a vibration plate and occurrence of variation in displacement are provided.
A flow path forming substrate having a flow path communicating with a nozzle opening, a vibration plate provided on one side of the flow path formation substrate, and an adhesive on the vibration plate. And the diaphragm 55 is provided with an island portion 59 as a thick portion to which the piezoelectric element 11 is adhered. A groove 62 is provided on at least one of the adhesive surfaces with the piezoelectric element 11.
[Selection] Figure 2

Description

  The present invention relates to a liquid ejecting head and a liquid ejecting apparatus that eject liquid, and more particularly, to an ink jet recording head and an ink jet recording apparatus that eject ink as liquid.

  As a typical example of a liquid ejecting head, for example, an ink jet recording head that ejects ink droplets from nozzle openings using pressure generated by displacement of a piezoelectric element is known. The ink jet recording head is configured by forming a part of a pressure generation chamber communicating with the nozzle opening with a vibration plate, deforming the vibration plate with a piezoelectric element, and applying pressure to the ink supplied to the pressure generation chamber, Ink droplets are ejected from the nozzle openings. The diaphragm is composed of a thick portion provided in a region opposite to each pressure generating chamber and a thin portion provided around the thick portion, and an end face of each piezoelectric element is provided with each thick wall portion. It is bonded to the part via an adhesive (for example, see Patent Documents 1 and 2).

JP 2004-327462 A JP 2003-17770 A

  However, when the thick part and the piezoelectric element are bonded, if the adhesive flows out onto the thin part, the displacement characteristic of the diaphragm in the thin part changes due to the outflowed adhesive, and the displacement of the piezoelectric element (vibration plate) There exists a problem that there exists a possibility that quantity may fall.

  In addition, there is a problem that variation in the amount of displacement of the piezoelectric element (vibration plate) due to variation in the amount of the adhesive flowing out to the thin-walled portion makes it impossible to make the ink droplet ejection characteristics uniform.

  Such a problem exists not only in the ink jet recording head but also in a liquid ejecting head that ejects liquid other than ink.

  In view of such circumstances, the present invention provides a liquid ejecting head and a liquid ejecting apparatus that can improve the liquid ejecting characteristics by suppressing the deterioration of the displacement characteristics of the piezoelectric element and the diaphragm and the occurrence of variations in the displacement amount. For the purpose.

An aspect of the present invention that solves the above problems includes a flow path forming substrate in which a flow path communicating with a nozzle opening is formed, a vibration plate provided on one surface side of the flow path forming substrate, and the vibration plate. A piezoelectric element bonded via an adhesive, and the diaphragm is provided with a thick portion to which the piezoelectric element is bonded, and an adhesive surface between the thick portion and the piezoelectric element At least one of the above is provided with a groove portion.
In such an aspect, the groove portion is provided on the bonding surface between the thick portion and the piezoelectric element, so that the adhesive for bonding the thick portion and the piezoelectric element is filled in the groove portion, and excess adhesive is formed in the thick portion. It can suppress flowing out of the outside. Accordingly, it is possible to make the liquid ejection characteristics uniform by reducing a decrease or variation in the displacement amount of the piezoelectric element and the diaphragm.

  Here, the groove portion may be provided on the adhesive surface on the thick portion side, and the groove portion may be provided on the adhesive surface on the piezoelectric element side.

According to another aspect of the invention, there is provided a liquid ejecting apparatus including the liquid ejecting head according to the above aspect.
In this aspect, it is possible to realize a liquid ejecting apparatus in which the liquid ejecting characteristics are uniformed and the printing quality is improved.

FIG. 3 is a cross-sectional view of the recording head according to the first embodiment of the invention. FIG. 3 is an enlarged cross-sectional view of a main part of the recording head according to Embodiment 1 of the invention. It is a perspective view of the piezoelectric element unit which concerns on Embodiment 1 of this invention. It is the top view and sectional drawing of a piezoelectric element unit which concern on Embodiment 1 of this invention. 1 is a diagram illustrating a schematic configuration of a recording apparatus according to an embodiment of the present invention.

Hereinafter, the present invention will be described in detail based on embodiments.
(Embodiment 1)
1A is a longitudinal sectional view of a pressure generation chamber of an ink jet recording head which is an example of a liquid jet head according to Embodiment 1 of the present invention, and FIG. 1B is an ink jet recording head. It is principal part sectional drawing of the transversal direction of this pressure generation chamber. FIG. 2 is an enlarged cross-sectional view of the main part of FIG.

  As shown in FIG. 1, the flow path forming substrate 50 is made of a silicon single crystal substrate, and a pressure generation chamber 52 defined by a plurality of partition walls 51 is formed in the width direction (short side) on the surface layer portion on one surface side. Direction). In addition, a reservoir 53 for supplying ink, which is an example of liquid, to each pressure generation chamber 52 is disposed on one end in the longitudinal direction of each pressure generation chamber 52 via an ink supply path 54, which is an example of a liquid supply path. It is communicated. Further, a nozzle plate 57 which is an example of a nozzle forming member in which the opening surface side of the pressure generating chamber 52 of the flow path forming substrate 50 is sealed with a vibration plate 55 and the nozzle opening 56 is formed on the other surface side is bonded. It is bonded via an agent or a heat welding film.

  The diaphragm 55 formed on the flow path forming substrate 50 includes, for example, an elastic film 55a made of an elastic member such as a resin film, and a support plate 55b made of, for example, a metal material that supports the elastic film 55a. It is formed of a composite plate, and the elastic film 55 a side is bonded to the flow path forming substrate 50. For example, in the present embodiment, the elastic film 55a is made of a PPS (polyphenylene sulfide) film having a thickness of about several μm, and the support plate 55b is made of a stainless steel plate (SUS) having a thickness of about several tens of μm. In addition, in the region of the vibration plate 55 facing each pressure generating chamber 52, an island portion 59 with which the tip portion of the piezoelectric element 11 abuts is provided. That is, a thin portion 60 that is thinner than other regions is formed in a region of the diaphragm 55 that faces the peripheral portion of each pressure generating chamber 52, and an island portion 59 is provided inside each thin portion 60. Yes. In the present embodiment, the diaphragm 55 is provided with the island portion 59 so that the diaphragm 55 is provided with a thick portion thicker than other regions (thin portions 60). In the present embodiment, a plurality of groove portions 62 are provided on the surface of the island portion 59, that is, on the surface opposite to the flow path forming substrate 50. The groove 62 may be provided along the longitudinal direction of the pressure generating chamber 52 or may be provided along the short direction of the pressure generating chamber 52, or may be provided in a lattice shape combining these. May be. Of course, the grooves 62 may be interspersed so as to be discontinuous in the plane of the island part 59.

  Further, in the region facing the reservoir 53 of the vibration plate 55, similarly to the thin portion 60, a compliance portion 61 that is substantially composed only of the elastic film 55 a is provided by removing the support plate 55 b by etching. . The compliance portion 61 absorbs the pressure change by the deformation of the elastic film 55a of the compliance portion 61 when a pressure change occurs in the reservoir 53, and always keeps the pressure in the reservoir 53 constant. Fulfill.

  A head case 58 having an ink supply path that is an example of a liquid supply path that is connected to an ink cartridge that is an example of a plurality of liquid reservoirs (not shown) is fixed on the vibration plate 55. The piezoelectric element unit 10 is positioned and fixed with high accuracy. That is, the head case 58 is provided with a housing portion 58 a that penetrates, the piezoelectric element unit 10 on one inner surface of the housing portion 58 a, and the pressure generating chambers 52 on the diaphragm 55 with the tips of the piezoelectric elements 11. Are bonded and fixed to each island portion 59 (thick portion) provided in a region corresponding to 1 through an adhesive 63.

  Here, the piezoelectric element unit 10 will be described in detail. FIG. 3 is a perspective view of the piezoelectric element unit according to Embodiment 1 of the present invention, and FIG. 4 is a plan view of FIG. 3 and a cross-sectional view taken along line AA ′ thereof.

  As shown in FIGS. 3 and 4, the piezoelectric element unit 10 according to this embodiment includes a piezoelectric element forming member 13 having a row 12 in which a plurality of piezoelectric elements 11 are arranged in the width direction, and a piezoelectric element forming member. 13 has a fixing plate 14 to which the base end portion (the other end portion) side is joined as a fixed end so that the tip end portion (one end portion) side thereof becomes the free end 11a.

  The piezoelectric element forming member 13 includes a piezoelectric material layer 15 and internal electrodes constituting two poles of the piezoelectric element 11, that is, individual internal electrodes 16 constituting individual electrodes electrically independent of the adjacent piezoelectric elements 11, It is formed by alternately stacking common internal electrodes 17 constituting common electrodes that are electrically common to adjacent piezoelectric elements 11.

  In the piezoelectric element forming member 13, a plurality of slits 18 are formed by, for example, a wire saw or the like, and the tip end side is cut into a comb-like shape to form a row 12 of piezoelectric elements 11. A positioning portion 19 having a width wider than each piezoelectric element 11 is provided on both outer sides of the row 12 of the piezoelectric elements 11. The positioning portion 19 is provided to position the piezoelectric element unit 10 with high accuracy when the piezoelectric element unit 10 is incorporated into the ink jet recording head I.

  Here, the individual internal electrodes 16 that are the individual electrodes of each piezoelectric element 11 are basically provided over substantially the entire surface of the piezoelectric element forming member 13, but in a region facing the vicinity of the end face of the fixed plate 14. It is provided separately on the distal end side and the proximal end side. On the other hand, the common internal electrode 17 serving as a common electrode is basically provided over substantially the entire surface of the piezoelectric element forming member 13, but is separated in the vicinity of the tip of the piezoelectric element 11, as with the individual internal electrode 16. Yes. That is, the region bonded to the fixed plate 14 of the piezoelectric element 11 is an inactive region that does not contribute to vibration, and when a voltage is applied between the individual internal electrode 16 and the common internal electrode 17 constituting the piezoelectric element 11, Only the region on the tip side that is not joined to the fixed plate 14 vibrates. In the present embodiment, as described above, the base end fixed to the fixed plate 14 of the piezoelectric element 11 is referred to as a fixed end 11b, and the vibrating tip of the piezoelectric element 11 is referred to as a free end 11a.

  An external electrode 20 connected to the individual internal electrode 16 and the common internal electrode 17 is formed on the outer surface of the piezoelectric element forming member 13. In addition, an electrode non-forming portion 21 where the external electrode 20 does not exist is present on the base end side of the region corresponding to at least the row 12 of the piezoelectric elements 11 of the piezoelectric element forming member 13.

  The plurality of slits 18 are formed so as to reach a region facing the electrode non-forming portion 21, and the external electrode 20 is separated by the slit 18 and the electrode non-forming portion 21, and the adjacent piezoelectric elements 11 are separated from each other. An individual external electrode 22 that is electrically independent and a common external electrode 23 that is electrically common to the adjacent piezoelectric elements 11 are configured.

  Specifically, in this embodiment, the external electrode 20 is separated into a portion facing each piezoelectric element 11 and a portion facing the positioning portion 19, and the external electrode 20 in a region facing each piezoelectric element 11 is An individual external electrode 22 that is electrically connected to the individual internal electrode 16 that constitutes the individual electrode of the piezoelectric element 11 is configured at the tip of the piezoelectric element forming member 13. On the other hand, the external electrode 20 on the positioning portion 19 provided on both sides of the row 12 of the piezoelectric elements 11 is a common internal electrode that constitutes a common electrode of each piezoelectric element 11 on the end face on the base end side of the piezoelectric element forming member 13. The common external electrode 23 connected to 17 is constituted.

  That is, in the piezoelectric element unit 10 of the present embodiment, the individual external electrodes 22 are arranged in parallel on the opposite surface of the portion of the piezoelectric element forming member 13 joined to the fixing plate 14, and the individual external electrodes 22 are arranged in parallel. Common external electrodes 23 exist in regions facing the positioning portion 19 on both sides in the installation direction. Thereby, the piezoelectric element unit 10 and the circuit board 30 to be described later can be connected relatively easily, and the piezoelectric element unit 10 can be downsized.

  In such a piezoelectric element unit 10, as shown in FIG. 1, the surface of the fixing plate 14 opposite to the surface on which the piezoelectric element forming member 13 is fixed is fixed to the accommodating portion 58 a of the head case 58. In addition, individual external electrodes 22 are formed on the front end surface of each piezoelectric element 11, and the end surface on which the individual external electrode 22 at the front end of each piezoelectric element 11 is formed is an island portion (thick portion) of the diaphragm 55. ) 59 via an adhesive 63. Here, as shown in FIG. 2, the end surface bonded to the island part 59 of the piezoelectric element 11 is provided so as to be wider than the width of the island part 59 in the short direction of the pressure generating chamber 52. For this reason, when the piezoelectric element 11 and the island portion 59 are bonded in a state where the adhesive 63 is applied to the end face of the piezoelectric element 11, the adhesive 63 applied to the end face of the piezoelectric element 11 is thinned outside the island portion 59. It tends to flow out to the part 60. However, in this embodiment, since the groove portion 62 is provided on the surface of the island portion 59, the excess adhesive 63 can be released into the groove portion 62, and the excess adhesive 63 is formed on the thin portion 60 from above the island portion 59. It can suppress flowing out. As a result, it is possible to suppress the decrease in the displacement amount of the diaphragm 55 due to the extra adhesive 63 adhering to the thin wall portion 60 and the occurrence of the variation in the displacement amount of the diaphragm 55 due to the variation in the outflow amount of the adhesive 63. In addition, the ink ejection characteristics can be improved and uniformized.

  Incidentally, the diaphragm 55 can be formed by joining the elastic film 55a and the support plate 55b and then removing the region other than the island portion 59 of the support plate 55b by etching. And the groove part 62 mentioned above may be formed by the etching at the time of forming the island part 59, for example, and may be formed by the sandblast method etc., for example. Of course, the groove 62 may be formed on the support plate 55b before joining the elastic film 55a and the support plate 55b, or may be formed after etching the support plate 55b.

  Further, a wiring board 33 provided with a plurality of conductive pads 32 to which the respective wirings 31 of the circuit board 30 are respectively connected is fixed on the head case 58, and the accommodating portion 58a of the head case 58 is provided with this wiring. The substrate 33 is substantially blocked. The wiring board 33 is formed with a slit-shaped opening 34 in a region facing the housing portion 58a of the head case 58, and the circuit board 30 is bent from the opening 34 of the wiring board 33 to the outside of the housing portion 58a. Being pulled out.

  Here, the circuit board 30 constituting the piezoelectric element unit 10 is made of, for example, a chip on film (COF) on which a driving IC (not shown) for driving the piezoelectric element 11 is mounted in the present embodiment. Each wiring 31 of the circuit board 30 has, on the base end side, external electrodes 20 (individual external electrodes 22), for example, electrode forming materials 16 and 17 constituting the piezoelectric element 11 by solder, anisotropic conductive material, or the like. And a common external electrode 23). On the other hand, on the tip end side, each wiring 31 is joined to each conductive pad 32 of the wiring substrate 33. Specifically, each wiring 31 is connected to the wiring board 33 in a state in which the front end portion of the circuit board 30 drawn out from the opening 34 of the wiring board 33 to the outside of the housing portion 58 a is bent along the surface of the wiring board 33. The conductive pads 32 are joined.

  In such an ink jet recording head I, when ejecting ink droplets, the volume of each pressure generating chamber 52 is changed by deformation of the piezoelectric element 11 and the vibration plate 55 so that the ink droplets are ejected from predetermined nozzle openings 56. It is designed to be discharged. Specifically, when ink is supplied to the reservoir 53 from an ink cartridge (not shown), the ink is distributed to each pressure generating chamber 52 via the ink supply path 54. Actually, the piezoelectric element 11 is contracted by applying a voltage to the piezoelectric element 11. As a result, the diaphragm 55 is deformed together with the piezoelectric element 11 to expand the volume of the pressure generation chamber 52, and ink is drawn into the pressure generation chamber 52. Then, after the ink is filled up to the nozzle opening 56, the voltage applied to the electrode forming materials 16 and 17 of the piezoelectric element 11 is released according to the recording signal supplied through the wiring substrate 33. As a result, the piezoelectric element 11 is expanded to return to the original state, and the diaphragm 55 is also displaced to return to the original state. As a result, the volume of the pressure generation chamber 52 contracts, the pressure in the pressure generation chamber 52 increases, and ink droplets are ejected from the nozzle openings 56.

(Other embodiments)
As mentioned above, although Embodiment 1 of this invention was demonstrated, the basic composition of this invention is not limited to what was mentioned above. For example, in Embodiment 1 described above, the groove portion 62 is provided in the island portion 59, but the present invention is not particularly limited to this, and the groove portion 62 may be provided on the end surface bonded to the island portion 59 of the piezoelectric element 11. Alternatively, it may be provided on both the end face of the piezoelectric element 11 and the island portion 59. Incidentally, since the individual external electrode 22 is formed on the end face of the piezoelectric element 11, the groove portion 62 may be provided in the individual external electrode 22, or the groove portion 62 is provided in the piezoelectric element forming member 13, and the groove portion 62. In addition, the individual external electrodes 22 having a uniform thickness may be provided. That is, if the groove 62 is provided on at least one of the end face of the piezoelectric element 11 and the surface of the island 59 which are the bonding surfaces of the piezoelectric element 11 and the thick part (island 59) of the diaphragm 55, the piezoelectric element 11 is piezoelectric. The outflow of the adhesive 63 that bonds the element 11 and the diaphragm 55 can be suppressed.

  Moreover, if the groove part 62 is provided along the outer peripheral side of the adhesive surface of the piezoelectric element 11 and the thick part (island part 59), the outflow to the thin part 60 of the adhesive agent 63 will be suppressed effectively. Can do. That is, by pressing the piezoelectric element 11 and the thick portion (island portion 59) together, the adhesive 63 that is about to protrude from the adhesive surface is effectively released into the groove portion 62 and the outflow of the adhesive 63 is suppressed. be able to.

  Further, in the first embodiment described above, the longitudinal vibration type piezoelectric element 11 in which the piezoelectric material layers 15 and the electrode forming materials (individual internal electrodes 16 and common internal electrodes 17) are alternately stacked and expanded and contracted in the axial direction has been described. However, a lateral vibration type piezoelectric element in which the piezoelectric material layers 15 and the electrode forming materials 16 and 17 are alternately stacked and one end portion in the stacking direction is in contact with the island portion 59 may be used.

  The ink jet recording head of the first embodiment described above constitutes a part of a recording head unit including an ink flow path communicating with an ink cartridge or the like, and is mounted on the ink jet recording apparatus. FIG. 5 is a schematic view showing an example of the ink jet recording apparatus.

  As shown in FIG. 5, the ink jet recording apparatus II includes recording head units 1 </ b> A and 1 </ b> B having an ink jet recording head I. The recording head units 1A and 1B are detachably provided with cartridges 2A and 2B constituting ink supply means. A carriage 3 on which the recording head units 1A and 1B are mounted is attached to a carriage shaft 5 attached to the apparatus main body 4. It is provided so as to be movable in the axial direction. The recording head units 1A and 1B, for example, are configured to eject a black ink composition and a color ink composition, respectively.

  The driving force of the driving motor 6 is transmitted to the carriage 3 via a plurality of gears and timing belt 7 (not shown), so that the carriage 3 on which the recording head units 1A and 1B are mounted is moved along the carriage shaft 5. The On the other hand, the apparatus body 4 is provided with a platen 8 along the carriage shaft 5, and a recording sheet S that is a recording medium such as paper fed by a paper feed roller (not shown) is wound around the platen 8. It is designed to be transported.

  In the first embodiment described above, an ink jet recording head has been described as an example of a liquid ejecting head. However, the present invention is widely intended for all liquid ejecting heads, and ejects liquids other than ink. Of course, the invention can also be applied to a liquid jet head. Other liquid ejecting heads include, for example, various recording heads used in image recording apparatuses such as printers, color material ejecting heads used in the manufacture of color filters such as liquid crystal displays, organic EL displays, and FEDs (field emission displays). Examples thereof include an electrode material ejection head used for electrode formation, a bioorganic matter ejection head used for biochip production, and the like.

  Further, although the ink jet recording apparatus II has been described as an example of the liquid ejecting apparatus, the liquid ejecting apparatus using the other liquid ejecting heads described above can also be used.

  I ink jet recording head (liquid ejecting head), II ink jet recording apparatus (liquid ejecting apparatus), 10 piezoelectric element unit, 11 piezoelectric element, 11a free end, 11b fixed end, 13 piezoelectric element forming member, 14 fixing plate, 16 Individual internal electrode, 17 Common internal electrode, 18 Slit, 19 Positioning part, 22 Individual external electrode, 23 Common external electrode, 30 Circuit board, 31 Wiring, 32 Conductive pad, 33 Wiring board, 50 Flow path forming board, 52 Pressure generation Chamber, 55 Diaphragm, 56 Nozzle opening, 58 Head case, 59 Island part (thick part), 60 Thin part, 61 Compliance part, 62 Groove part, 63 Adhesive

Claims (4)

A flow path forming substrate in which a flow path communicating with the nozzle opening is formed;
A diaphragm provided on one side of the flow path forming substrate;
A piezoelectric element bonded to the diaphragm via an adhesive,
The diaphragm is provided with a thick part to which the piezoelectric element is bonded,
A liquid ejecting head, wherein a groove portion is provided on at least one of the bonding surfaces of the thick portion and the piezoelectric element.   The liquid ejecting head according to claim 1, wherein the groove portion is provided on the adhesive surface on the thick portion side.   The liquid ejecting head according to claim 1, wherein the groove is provided on the adhesive surface on the piezoelectric element side.   A liquid ejecting apparatus comprising the liquid ejecting head according to claim 1.

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