JP5119777B2 - Liquid ejection device - Google Patents

Description

The present invention relates to a pressure chamber provided in the middle of a liquid flow path leading to a discharge port, a piezoelectric layer that changes the volume of the pressure chamber, and a power supply electrode that is electrically connected to the piezoelectric layer and applies a voltage thereto It relates to a liquid ejection equipment with and.

  Conventionally, as an example of a liquid ejecting apparatus using an ink jet printer, liquid such as ink is ejected from a discharge port formed at a downstream end of a liquid flow path formed in a flow path unit toward a recording medium. What was comprised so that it might be made to be known is known. More specifically, a pressure chamber having a predetermined volume in the middle of the liquid flow path is formed so as to have a part of the opening, and the piezoelectric layer can be deformed by an applied voltage so as to cover the opening of the pressure chamber. Is provided. This piezoelectric layer is sandwiched between a common electrode (common electrode 34) held at a predetermined potential and a drive electrode (individual electrode 35) to which a predetermined potential different from the common electrode is applied by an applied voltage. Yes. Furthermore, power supply electrodes (contacts 54 of the FPC 50) for applying a predetermined potential to the drive electrodes are disposed close to the drive electrodes, and these drive electrodes and power supply electrodes are electrically connected by solder or conductive adhesive. It is the structure connected to (refer patent document 1).

When power is supplied from the external power source to the power supply electrode, a voltage is applied to the drive electrode connected thereto, and a potential difference is generated between the common electrode held at a predetermined voltage. As a result, the shape of the piezoelectric layer changes and the volume of the pressure chamber also changes, so that the liquid in the pressure chamber is pressurized and discharged from the discharge port to the outside through the liquid channel.
JP 2004-114609 A

  By the way, in the case of the liquid ejection apparatus having the above-described configuration, the electrical contact between the drive electrode and the solder (the region where the land 36 on the individual electrode 35 is formed) is viewed along the thickness direction of the piezoelectric layer. Are provided outside the area occupied by the pressure chamber. That is, since solder is generally inflexible in the cured state, when an electrical contact with the drive electrode is provided in the region, the shape change of the portion corresponding to the pressure chamber in the piezoelectric layer occurs when a voltage is applied. It will be disturbed. Then, since it becomes difficult to change the volume of the pressure chamber appropriately, in order to avoid this, a wiring is extended from the drive electrode to the outside of the area, and the wiring and the solder are connected outside the area. ing.

  However, with such a configuration, as described above, it is necessary to extend wiring for electrical connection to the outside of the area occupied by one pressure chamber as described above. When a pressure chamber is provided, it is difficult to achieve high integration. As a result, it becomes difficult to realize the demand for further miniaturization of the flow path unit and further improvement of resolution in printed matter such as photographs.

The present invention, while achieving the improved resolution of the image formed by the size and the ejection liquid of the channel unit, to provide a liquid discharge equipment which makes it possible to properly shape change of the piezoelectric layer Objective.

The present invention has been made in view of the circumstances as described above, and a pressure chamber provided in the middle of a liquid flow path leading to the discharge port so that liquid is discharged from the discharge port by volume change, and the pressure chamber A piezoelectric layer that changes volume, and a feeding electrode that is electrically connected to the piezoelectric layer and applies a voltage to the piezoelectric layer, the piezoelectric layer being deformable by an applied voltage, and having one surface of the pressure chamber The other surface of the piezoelectric layer is electrically connected by a liquid conductive material, and the other surface of the piezoelectric layer has the pressure chamber as viewed in the thickness direction. possess a contact region to be electrically contact with the liquid electroconductive material in the region occupied by said liquid conductive material, when the piezoelectric layer is deformed driven by an applied voltage, the predetermined that does not interfere with the deformation of the piezoelectric layer It has fluidity.

With such a configuration, since the liquid conductive material is used for electrical connection, the piezoelectric layer and the feeding electrode can be electrically connected without hindering the shape change in the region of the piezoelectric layer. In addition to this, since the contact area between the piezoelectric layer and the liquid conductive material is located in the area occupied by the pressure chamber, it is possible to achieve high integration of the pressure chamber. It is possible to reduce the size of a flow path unit provided with a large number of liquid flow paths having a chamber in the middle and to improve the resolution of an image formed by the discharged liquid .

  In addition, a drive electrode is joined to the other surface of the piezoelectric layer so as to at least partially overlap the contact region, and the piezoelectric layer and the feeding electrode are connected to the liquid conductive material via the drive electrode. May be electrically connected. With this configuration, the liquid conductive material and the piezoelectric layer can be connected with low resistance.

That is, the piezoelectric layer formed by the aerosol deposition method (Aerosol Deposition method: AD method) or the like has a rough surface, so that when the piezoelectric layer and the liquid conductive material are in direct contact, the liquid conductive material Depending on the viscosity (that is, when the viscosity is relatively high), a sufficient contact area cannot be secured, and the resistance at the contact may increase. On the other hand, when the piezoelectric layer and the liquid conductive material are connected via a drive electrode provided separately on the surface of the piezoelectric layer, the drive electrode can be driven by using a relatively smooth surface shape. A large contact area between the electrode and the liquid conductive material can be secured, and as a result, the piezoelectric layer and the liquid conductive material can be connected with low resistance. In addition, as a drive electrode, what was formed on the surface of the piezoelectric layer can be employ | adopted from the well-known method of screen-printing and drying, for example, electrically conductive paste (The thing of a silver-palladium-type paste etc.). The drive electrode formed in this way is sufficiently adhered to the piezoelectric layer and has a relatively smooth outer surface.

  Further, a liquid-tight conductive material accommodating space for accommodating the liquid conductive material may be formed between the contact region in the piezoelectric layer and the power supply electrode. By setting it as such a structure, a liquid electrically-conductive material can be enclosed in the said accommodation space.

  The first insulating layer is further provided on the other surface of the piezoelectric layer, and the first insulating layer has a first through hole that exposes the contact region and constitutes the conductive material accommodating space. It may be formed. With such a configuration, the other surface of the piezoelectric layer can be electrically insulated except for the contact region, and the liquid conductive material can be made to contact the contact region with certainty. It can accommodate in the 1st through-hole of a 1st insulating layer.

  The circuit board further includes a wiring board having the power feeding electrode, the wiring board having a base material provided with the power feeding electrode on one surface, and the power feeding electrode electrically connected to the one surface of the base material. And a second insulating layer covering the wiring on the base material, the second insulating layer partially facing a surface of the power supply electrode facing the contact region The first through hole is exposed to the first insulating layer, and the first insulating layer and the second insulating layer are joined to each other so that the first through hole and the second through hole communicate with each other and contain the conductive material. A space may be formed.

  With such a configuration, only the surface of the power supply electrode facing the contact region can be exposed to electrically insulate other wiring and the like, and the liquid conductive material can be surely exposed on the exposed portion of the power supply electrode. The liquid conductive material can be accommodated in the second through hole of the second insulating layer so as to come into contact. Furthermore, it is also possible to form a conductive material accommodation space by such a first through hole and a second through hole and enclose a liquid conductive material therein.

  The power supply electrode may have a bump protruding toward the piezoelectric layer from the opening surface of the first through hole of the first insulating layer. By adopting such a configuration, the power supply electrode and the liquid conductive material can be reliably brought into contact with each other by immersing the bump in the liquid conductive material.

  The bump may be formed of a press bump formed by pressing the power supply electrode, a solder bump formed by soldering the power supply electrode, or a spiral contact. With such a configuration, in the case of a press bump or solder bump, bump formation can be realized easily and inexpensively, and in the case of a spiral contact, contact with a liquid conductive material is more reliable. Can be.

  Moreover, the said electrically-conductive material accommodation space may have a surplus volume other than the accommodation volume of the said liquid electrically-conductive material. By adopting such a configuration, even when the liquid conductive material is thermally expanded during use of the liquid discharge device, the volume fraction increased by the expansion is absorbed by the surplus volume portion of the conductive material accommodation space. Can do.

  In addition, a recess capable of accommodating the liquid conductive material leaking from the first through hole may be formed in the vicinity of the periphery of the first through hole of the first insulating layer. With such a configuration, even when the liquid conductive material leaks from the first through hole forming the conductive material accommodation space when the piezoelectric layer and the feeding electrode are joined via the first insulating layer. By receiving the leaked liquid conductive material in the recess, further diffusion of the liquid conductive material can be prevented.

According to the liquid discharge equipment according to the present invention, a liquid ejecting device capable of being electrically connected to the piezoelectric layer and the feeding electrode without interfering with the shape change in the region occupied by the pressure chamber in the thickness direction as viewed in the piezoelectric layer Can be realized. In addition, it is possible to achieve high integration of pressure chambers, and it is possible to reduce the size of a flow path unit provided with a number of liquid flow paths having such pressure chambers in the middle, and images formed by discharged liquid. It is possible to realize a liquid ejection apparatus capable of improving the resolution.

  Hereinafter, a liquid discharge apparatus and a manufacturing method thereof according to an embodiment of the present invention will be specifically described with reference to the drawings, taking an ink jet printer as an example.

(Embodiment 1)
FIG. 1 is a schematic perspective view of a liquid ejection apparatus 1 according to Embodiment 1 of the present invention. As shown in FIG. 1, a liquid ejection apparatus 1 that is an ink jet printer has a guide rod 3 installed on a housing 2, and a carriage 4 can slide along the guide rod 3 on the guide rod 3. It is supported by. A recording head 5 is provided below the carriage 4, and the recording head 5 is configured to be able to eject ink (liquid) downward.

  Pulleys 7 and 7 are disposed in the vicinity of both ends of the guide rod 3, and a timing belt 8 is wound between the pulleys 7 and 7. One pulley 7 is connected to an output shaft of a motor 9 capable of rotating in the forward and reverse directions, and the rotation of the motor 9 allows the timing belt 8 to rotate in one direction and the other direction. The timing belt 8 is connected to the carriage 4. As the timing belt 8 circulates, the recording head 5 along with the carriage 4 reciprocates in one direction and the other direction along the guide rod 3. To do.

  Below the recording head 5 is a conveyance path for the recording paper 10 constituting the recording medium, and a paper feed roller 11 installed on the housing 2 so that the rotation axis is parallel to the guide rod 3. Thus, the recording paper 10 is conveyed below the recording head 5 along the conveyance path. Therefore, when the recording head 5 is positioned above the recording paper 10, the recording head 5 is reciprocated while intermittently transporting the recording paper 10, and ink is ejected from the recording head 5 during these operations. Thus, a desired image can be formed by attaching ink to a predetermined position on the recording paper 10.

  In the following description, the “scanning direction” refers to the direction in which the recording head 5 moves along the guide rod 3, and the “conveyance direction” refers to the direction in which the recording paper 10 is conveyed directly below the recording head 5. If it is different from these or other directions, explanations will be given as appropriate.

2 is a schematic plan view when the recording head 5 is viewed from above, FIG. 3 is an enlarged schematic plan view showing a part of the recording head 5 shown in FIG. 2, and FIG. FIG. 4 is a schematic cross-sectional view when the recording head 5 shown in FIG. 3 is cut along line IV-IV. As shown in FIG.
A liquid flow path 30 (see FIG. 4), which will be described later, is mainly composed of a flow path unit 15 formed inside and an actuator 16 connected to the upper surface thereof. In the upper part of the flow path unit 15, a plurality of pressure chamber holes 21 a having a long oval shape in the scanning direction are arranged in parallel in the transport direction to form one pressure chamber hole row 17, like this A plurality (two in FIG. 2) of adjacent pressure chamber hole rows 17 are arranged adjacent to each other in the scanning direction. The actuator 16 includes a chip on film (COF) 16 a having a supply electrode 46 provided corresponding to each pressure chamber hole 17.
And a drive layer 16b composed of a piezoelectric layer 20 and the like which will be deformed by applying a voltage to the supply electrode 46 (see also FIG. 4).

[Recording head]
The configuration of the recording head 5 will be further described in detail with reference to FIGS. First, as shown in FIG. 4, the flow path unit 15 has a configuration in which a pressure chamber plate 21, a connection flow path plate 22, a manifold plate 23, and a nozzle plate 24 are laminated and bonded in order from above.

  The pressure chamber plate 21 is formed with a pressure chamber hole 21 a (see also FIG. 3) having an oval shape as described above, and the connection flow path plate 22 connected to the lower surface of the pressure chamber plate 21 includes A liquid inflow hole 22a communicating with one end of the pressure chamber hole 21a and a first liquid outflow hole 22b communicating with the other end of the pressure chamber hole 21a are formed. The manifold plate 23 has a manifold hole 23a having a relatively large opening area and extending in the transport direction (see also FIG. 2), and the manifold hole 23a is all that constitutes one pressure chamber hole row 17 (see FIG. 2). Communication with each other through the liquid inflow holes 22a. The manifold plate 23 is formed with a second liquid outflow hole 23b separately from the manifold hole 23a, and the second liquid outflow hole 23b communicates with the pressure chamber hole 21a through the first liquid outflow hole 22b. . Furthermore, the nozzle plate 24 has a nozzle hole 24a that communicates with the pressure chamber hole 21a through the first liquid outflow hole 22b and the second liquid outflow hole 23b, and the nozzle hole 24a has a smaller diameter as it goes downward. Is formed.

  When such plates 21 to 24 are laminated and bonded, the manifold hole 23a described above is closed from below in the nozzle plate 24 by a portion other than the nozzle hole 24a, and the liquid inflow hole 22a of the connection flow path plate 22 and The common liquid chamber 31 is formed by being partially closed from above by a portion other than the first liquid outflow hole 22b. The pressure chamber hole 21a is closed from above by a metal vibration plate 25 laminated and bonded to the pressure chamber plate 21, and a portion other than the liquid inflow hole 22a and the first liquid outflow hole 22b of the connection flow path plate 22. The pressure chamber 33 is formed by being partially closed by the above.

  Further, the liquid inflow hole 22a of the connection flow path plate 22 forms a liquid inflow path 32 that communicates between the common liquid chamber 31 and the pressure chamber 33, and the connection flow path plate 22 and the manifold plate 23 are respectively connected. The first liquid outflow hole 22b and the second liquid outflow hole 23b that are in communication with each other form a liquid outflow path 34 that communicates between the pressure chamber 33 and the nozzle hole 24a. The common liquid chamber 31, the liquid inflow path 32, the pressure chamber 33, the liquid outflow path 34, and the nozzle hole 24a constitute a continuous liquid flow path 30 through which ink flows.

  In addition, as shown in FIG. 2, two common liquid chambers 31 provided corresponding to the two pressure chamber hole rows 17 communicate with each other, and these common liquid chambers 31 are connected to the pressure chamber plate 21 and the connection. The ink is communicated with an ink tank (not shown) provided separately from the recording head 5 through a through hole 35 formed in the flow path plate 22. Therefore, the ink from the ink tank is supplied to the common liquid chamber 31 through the through hole 35 and is filled in the liquid flow path 30 from the common liquid chamber 31 to the nozzle hole 24a. When the vibration plate 25 that forms the upper wall of the pressure chamber 33 vibrates by driving the actuator 16, the volume of the pressure chamber 33 changes, and pressure is applied to the ink in the pressure chamber 33, so that the ink flows into the liquid flow path 30. The ink is pumped to the upstream side of the nozzle and injected to the outside from the nozzle hole 24a.

[Actuator]
Next, the actuator 16 will be described. As shown in FIG. 4, the actuator 16 is composed of a chip-on film 16a forming an upper layer and a driving layer 16b forming a lower layer, and the driving layer 16b includes a piezoelectric layer 20, a common electrode 40 sandwiching the piezoelectric layer 20, and The driving electrode 41 and a first insulating layer 42 laminated on the upper surface of the piezoelectric layer 20 are included.

  The drive layer 16b will be described in more detail. The common electrode 40 is laminated on the upper surface of the vibration plate 25 (the surface opposite to the surface facing the flow path unit 15), and the piezoelectric layer 20 is formed on the upper surface of the common electrode 40. Are stacked. The piezoelectric layer 20 is made of a piezoelectric material mainly composed of lead zirconate titanate (PZT), which is a solid solution of lead titanate and lead zirconate and is a ferroelectric substance. In other words, the pressure chambers 33 are formed in layers. As a forming method thereof, a known film forming technique may be used. For example, an AD method in which submicron-sized fine particles are mixed with a gas to form an aerosol and sprayed through a nozzle can be used. Note that a non-conductive layer made of alumina or the like is formed on the upper surface of the diaphragm 25, and the common electrode 40 is disposed on the upper surface of the non-conductive layer, so that the diaphragm 25 and the common electrode 40 are electrically connected to each other. It is in an insulated state.

  The drive electrode 41 is disposed on the upper surface of the piezoelectric layer 20 and can be formed by screen-printing a conductive paste such as a silver-palladium paste, for example, as viewed in the thickness direction of the piezoelectric layer 20 (ie, in plan view). It is provided so as to overlap with a region occupied by the pressure chamber 33, that is, a pressure chamber region 33a (see FIGS. 3 and 4). Further, as shown in FIG. 3, the drive electrode 41 according to the present embodiment forms a rhombus having diagonal lines substantially the same as the longitudinal dimension and the width dimension of the oval-shaped pressure chamber region 33a, It arrange | positions so that it may not protrude from the pressure chamber area | region 33a (all fits). Since the pressure chamber region 33a is a region occupied by the pressure chamber 33 in a plan view as described above, a portion overlapping the pressure chamber region 33a in the piezoelectric layer 20 is applied when ink is ejected from the nozzle hole 24a. It is preferable that it can be greatly deformed by the voltage.

  The first insulating layer 42 has a first through hole 42 a that exposes the drive electrode 41 and is laminated on the upper surface of the piezoelectric layer 20. The first insulating layer 42 is configured to be thicker than the drive electrode 41 by a non-conductive material such as polyimide, and a first through hole 42 a is formed corresponding to the drive electrode 41. As shown in FIG. 3, the first through hole 42a has a rhombus similar to that of the drive electrode 41, and the upper surface of the drive electrode 41 is exposed through the first through hole 42a. A liquid conductive material 50 is accommodated in a concave space formed by the first through hole 42 a and the drive electrode 41.

  On the other hand, the chip-on film 16a that forms the upper layer of the actuator 16 has a pressing plate 44 made of a metal plate, and a TAB sheet 45 made of polyimide is provided on the lower surface of the pressing plate 44. A plurality of power supply electrodes 46 provided on the lower surface of the TAB sheet 45 corresponding to each pressure chamber 33, and a second insulating layer 47 having a second through hole 47a for partially exposing the power supply electrode 46, Is provided. The second insulating layer 47 is made of a resist. Note that the second insulating layer 47 may be made of polyimide and the TAB sheet 45 may be made of resist.

  Each power supply electrode 46 is disposed so as to face the drive electrode 41 of the drive layer 16b when the chip-on film 16a is bonded to the drive layer 16b, as shown in the bottom view of FIG. The electrode portion 46a has a disk shape, and the wiring connection portion 46b extends outward from the electrode portion 46a. A bump 46c protruding downward by press molding is formed at the center of the electrode portion 46a (see FIG. 4), and a driver IC (not shown) included in the chip-on film 16a is formed on the wiring connection portion 46b. One end of a wiring 46d that connects the two is connected.

  As shown in FIG. 5, the second through hole 47 a of the second insulating layer 47 has a circular opening and is provided corresponding to each power supply electrode 46. The second insulating layer 47 exposes only the central portion including the bump 46c of the electrode portion 46a of the power supply electrode 46 through the second through hole 47a, and the other portion of the power supply electrode 46 and the wiring 46d are laid. The lower surface of the TAB sheet 45 is covered.

  As shown in FIG. 4, in the actuator 16, the chip-on film 16a is bonded to the driving layer 16b as described above, and the upper surface of the first insulating layer 42 and the lower surface of the second insulating layer 47 are bonded by an adhesive 48. Are joined together. Thus, a liquid-tight conductive material accommodation space 51 is formed by the first through-hole 42a, the second through-hole 47a, the piezoelectric layer 20 (or the drive electrode 41), and the power supply electrode 46, and the liquid conductive material 50 is formed therein. Is enclosed. Further, the conductive material accommodation space 51 has a surplus volume in addition to the volume of the liquid conductive material 50. That is, the surplus space 51a where the liquid conductive material 50 does not exist is formed in the vicinity of the peripheral edge of the bump 46c in the conductive material accommodation space 51.

  In the above description, the first insulating layer 42, the second insulating layer 47, and the adhesive 48 are configured separately, but the first insulating layer 42 or the second insulating layer 47 itself has adhesiveness to the surface layer. If it consists of material, the separate adhesive 48 is unnecessary.

  Furthermore, the chip-on film 16a is bonded to the drive layer 16b, so that the bumps 46c of the power supply electrode 46 are disposed opposite to the power supply electrode 46 and from the opening surface 42b (see FIG. 4) of the first insulating layer 42. It protrudes downward and is immersed in the liquid conductive material 50. As a result, the drive electrode 41 and the power feeding electrode 46 are in an electrically connected state via the liquid conductive material 50.

[Actuator manufacturing method]
A manufacturing method of the actuator 16 described above will be described with reference to FIGS. As shown in FIGS. 6A to 6D, in the first to fourth steps of the manufacturing method, the drive layer 16b is formed on the upper part of the flow path unit 15, and FIGS. The chip-on film 16a is formed in the fifth to seventh steps shown, and the actuator 16 is finally formed in the eighth step shown in FIG. 7 (d).

  First, in the first step, the common electrode 40 is laminated on the upper surface of the diaphragm 25 provided on the upper part of the flow path unit 15, and the piezoelectric layer 20 is further laminated on the upper surface of the common electrode 40. In the subsequent second step, the drive electrode 41 is disposed on the upper surface of the piezoelectric layer 20 (see FIG. 6A). Thus, the common electrode 40 is bonded to the lower surface (the surface facing the pressure chamber 33) of the piezoelectric layer 20, and the drive electrode 41 is bonded to the upper surface. Further, when the drive electrode 41 is bonded to the piezoelectric layer 20, the drive electrode 41 is provided so as to correspond to the position of the pressure chamber 33 (more specifically, overlap).

  In the third step, the first insulating layer 42 having the first through holes 42a is stacked on the upper surface of the piezoelectric layer 20 (see FIG. 6C). At this time, the drive electrode 41 is exposed through the first through hole 42a, and as a result, the pressure chamber region 33a, the drive electrode 41, and the first through hole 42a overlap in plan view. The first insulating layer 42 can be formed by photolithography or screen printing. In the former case, the surface of the applied photosensitive material is partially masked and exposed to form the first insulating layer 42 having the shape described above. One through-hole 42a can be formed. From the viewpoint of forming the fine first through hole 42a, photolithography is more preferable than screen printing.

  In the fourth step, the liquid conductive material 50 is injected into the first through hole 42a (see FIG. 6D), and the piezoelectric layer 20 and the liquid conductive material 50 are electrically contacted via the drive electrode 41. The Here, the electrical contact region 20a between the piezoelectric layer 20 and the liquid conductive material 50 (equal to the region where the drive electrode 41 and the piezoelectric layer 20 are joined in this embodiment) is located in the pressure chamber region 33a. ing. In addition, although the liquid conductive material 50 to be injected is very small, as an example, the liquid conductive material 50 is sucked into an extremely thin glass tube by a capillary phenomenon, and the tip of the glass tube is driven to the drive electrode in the first through hole 42a. The injection can be performed by a known method of reprinting with the upper surface of 41 approached.

  On the other hand, in the fifth step, the power supply electrode 46 as shown in FIG. 5 is adhered to the lower surface of the pre-wired TAB sheet 45 (see FIG. 7A), and the power supply electrode 46 and the wiring are connected. . In the next sixth step, the second insulating layer 47 is laminated on the lower surface of the TAB sheet 45 so that the second through hole 47a is located in the central portion of the power supply electrode 46 (see FIG. 7B). The second through hole 47a is formed by etching or laser processing. As a result, the central portion of the power supply electrode 46 is exposed through the second through hole 47 a, and the other portion is covered with the second insulating layer 47, and the wiring 46 d connected to the power supply electrode 46 is also covered. Note that the second insulating layer 47 can also be formed by photolithography or screen printing in the same manner as the first insulating layer 42.

  Further, in the seventh step, a bump 46 c protruding downward is formed by press molding at the central portion of the power supply electrode 46 exposed through the second through hole 47 a, and then a pressing plate 44 made of a metal plate is formed on the upper surface of the TAB sheet 45. Are joined (see FIG. 7C). The bumps 46c are formed so as to protrude downward from the lower surface of the second insulating layer 47, in other words, to protrude downward from the lower opening surface of the second through hole 47a.

  Finally, the chip-on film 16a formed as described above is bonded to the drive layer 16b formed up to the fourth step (see FIG. 7D). That is, by connecting the upper surface of the first insulating layer 42 included in the driving layer 16b and the lower surface of the second insulating layer 47 included in the chip-on film 16a via the adhesive 48, the chip-on film 16a is connected to the driving layer 16b. The actuator 16 is manufactured by bonding.

  In this joining, the bumps 46c of the chip-on film 16a are opposed to the contact region 20a between the piezoelectric layer 20 and the liquid conductive material 50, and the first through hole 42a and the second through hole 47a communicate with each other. Thus, the liquid conductive material 50 is sealed in a liquid-tight conductive material accommodation space 51 formed by the first through hole 42 a, the second through hole 47 a, the piezoelectric layer 20 (or the drive electrode 41), and the power supply electrode 46. Like that. As a result, when the actuator 16 is viewed in plan, the potential supply section 55 (see FIG. 7D) including the bump 46c of the power supply electrode 46, the drive electrode 41, and the contact region 20a are all in the pressure chamber region 33a. In this state, the feeding electrode 46 and the drive electrode 41 are electrically connected by the liquid conductive material 50.

  In the recording head 5 having the actuator 16 formed in this way, when a voltage is applied to the power supply electrode 46 through the wiring 46d (see FIG. 5), the drive electrode connected to the power supply electrode 46 through the liquid conductive material 50. 41 has a potential different from that of the common electrode 40. As a result, due to the electric field generated between the drive electrode 41 and the common electrode 40, the shape of the piezoelectric layer 20 sandwiched between them changes and the shape of the diaphragm 25 also changes. As a result, the volume of the pressure chamber 33 changes, and the ink in the pressure chamber 33 is ejected to the outside through the liquid channel 30 from the nozzle hole 24a.

  According to the liquid ejecting apparatus 1 described above, since the potential supply unit 55 is located in the pressure chamber region 33a when viewed in plan, the potential supply unit 55 can be reduced in shape in plan view. High integration between the pressure chambers 55 and the corresponding pressure chambers 33 is possible. Further, as the pressure chamber 33 is highly integrated, it is possible to reduce the size of the recording head 5 and improve the resolution of an image formed by the ejected liquid.

  In addition, since the feeding electrode 46 and the drive electrode 41 are connected by the liquid conductive material 50, the contact region 20a between the piezoelectric layer 20 and the liquid conductive material 50 is located in the pressure chamber region 33a. Regardless, the portion of the piezoelectric layer 20 overlapping the pressure chamber region 33a is not prevented from changing its shape by the applied voltage. Accordingly, since this overlapping portion of the piezoelectric layer 20 can be greatly deformed, it is easy to control the degree of deformation of the piezoelectric layer 20 when ink is ejected from the nozzle holes 24a, and the voltage applied to the piezoelectric layer 20 during deformation is reduced. Can be achieved.

  In addition, since there is an excess space 51a (see FIG. 4) in the conductive material accommodation space 51 in addition to the volume occupied by the liquid conductive material 50, it is assumed that the liquid conductive material 50 expands due to heat generated when the recording head 5 is driven. In addition, the expansion volume can be accommodated in the surplus space 51a, and the liquid conductive material 50 can be prevented from leaking out of the conductive material accommodating space 51.

  Furthermore, since the actuator 16 according to the present embodiment connects the liquid conductive material 50 and the piezoelectric layer 20 via the drive electrode 41, the electrical resistance between them can be reduced. That is, by adopting a relatively smooth surface shape as the drive electrode 41, a large contact area between the drive electrode 41 and the liquid conductive material 50 can be secured. Therefore, it is possible to connect the piezoelectric layer 20 and the liquid conductive material 50 with a low resistance rather than directly contacting the piezoelectric layer 20 having a rough surface shape and the liquid conductive material 50 directly.

(Embodiment 2)
FIG. 8 is a partial cross-sectional view showing the configuration of the actuator 60 provided in the liquid ejection apparatus 1 according to the second embodiment. In the actuator 60, the drive electrode 41 is not provided on the upper surface of the piezoelectric layer 20, and the liquid conductive material 50 sealed in the conductive material accommodation space 51 is directly connected to the upper surface of the piezoelectric layer 20. A contact region 60a between the liquid conductive material 50 and the piezoelectric layer 20 (in this embodiment, the same as the lower opening region of the first through hole 42a) is located in the pressure chamber region 33a. Since the other configuration of the actuator 60 is the same as the configuration of the actuator 16 described in the first embodiment, the description thereof is omitted by attaching the same reference numerals to the corresponding configurations.

  Further, in the manufacturing method of the actuator 60 as described above, the second step (step of disposing the drive electrode 41) shown in FIG. 6B is omitted in the manufacturing method of the actuator 16 described in the first embodiment. These are the same as those constituted by the first step and the third to eighth steps. Therefore, the description in Embodiment 1 is referred to for the description, and detailed description thereof is omitted here.

  Also in the liquid ejecting apparatus 1 equipped with such a recording head 5 having the actuator 60, the power supply electrode 46 and the contact region 60a are located (or overlapped) in the pressure chamber region 33a when seen in a plan view. Since the visual shape can be made compact, the pressure chamber 33 can be highly integrated and the recording head 5 can be miniaturized. In addition, since the power supply electrode 46 and the piezoelectric layer 20 are connected by the liquid conductive material 50, the piezoelectric layer 20 located in the pressure chamber region 33a is not prevented from changing its shape by the applied voltage. Furthermore, since the drive electrode 41 is not provided, the number of parts and the number of manufacturing steps can be reduced, and the cost can be reduced.

(Embodiment 3)
9A and 9B are diagrams showing the configuration of the actuator 65 provided in the liquid ejection apparatus 1 according to Embodiment 3, wherein FIG. 9A is a partial cross-sectional view, and FIG. 9B is a plan view of the first insulating layer. Yes. As shown in FIG. 9A, in the actuator 65, the lower portion of the peripheral portion of the second through hole 47a of the second insulating layer 47 facing the conductive material accommodation space 51 is cut out obliquely. It becomes the taper part 65a. Accordingly, the volume of the conductive material accommodation space 51 is increased, and a larger volume of the liquid conductive material 50 during thermal expansion can be accommodated.

  Further, as shown in FIGS. 9A and 9B, a recess 65b that opens to the surface (upper surface) facing the second insulating layer 47 is formed in the first insulating layer 42 near the periphery of the first through hole 42a. Has been. As shown in FIG. 9B, the recess 65b is formed so as to surround the first through hole 42a in a plan view. Therefore, when the chip-on film 16a is bonded to the drive layer 16b, even if the liquid conductive material 50 overflows from the first through hole 42a due to the immersion of the bump 46c, the overflowed portion is accommodated in the recess 65b. Further leakage outside can be prevented.

  Further, in the liquid ejecting apparatus 1 equipped with such a recording head 5 having the actuator 65, the pressure chamber 33 is highly integrated and the recording head 5 is miniaturized in the same manner as described in the first and second embodiments. In addition, the piezoelectric layer 20 located in the pressure chamber region 33a is not prevented from changing its shape by the applied voltage.

  Since the other configuration of the actuator 65 is the same as the configuration of the actuator 16 described in the first embodiment, the description thereof is omitted by attaching the same reference numerals to the corresponding configurations.

(Embodiment 4)
FIG. 10 is a partial cross-sectional view illustrating a configuration of an actuator 70 provided in the liquid ejection apparatus 1 according to the fourth embodiment. As shown in FIG. 10, in the case of this actuator 70, the power feeding electrode 71 has solder bumps 72 formed by soldering instead of the bumps 46c according to the first embodiment formed by pressing. Even in such a configuration, the solder bump 72 can be immersed in the liquid conductive material 50, and the power supply electrode 71 and the drive electrode 41 can be connected via the liquid conductive material 50.

  Further, in the liquid ejecting apparatus 1 equipped with such a recording head 5 having the actuator 70 as well, as in the first to third embodiments, the pressure chamber 33 is highly integrated and the recording head 5 is downsized. The piezoelectric layer 20 positioned in the pressure chamber region 33a is not prevented from changing its shape by the applied voltage.

  Since the other configuration of the actuator 70 is the same as the configuration of the actuator 16 described in the first embodiment, the description thereof is omitted by attaching the same reference numerals to the corresponding configurations.

(Embodiment 5)
FIG. 11 is a partial cross-sectional view illustrating a configuration of an actuator 75 provided in the liquid ejection apparatus 1 according to the fifth embodiment. As shown in FIG. 11, in the case of this actuator 75, the feeding electrode 76 has a metal spiral contact 77 instead of the press-molded bump 46c according to the first embodiment and the solder bump 72 according to the fourth embodiment. is doing.

  As shown in the bottom view of FIG. 12, the spiral contact 77 has a metal terminal 77a spirally wound from the outer peripheral portion toward the center, and further wound toward the center as shown in FIG. As it is, it projects downward and is configured to be an inverted triangle when the overall appearance is viewed from the side. And the lower part is immersed in the liquid electrically-conductive material 50, and the lower end part 77b is contacting the drive electrode 41 directly. Therefore, with such a configuration, the feeding electrode 76 and the drive electrode 41 are more reliably connected via the liquid conductive material 50, and the spiral contact 77 has a large contact area with the liquid conductive material 50. The connection resistance between the two can be reduced.

  Further, in the liquid ejecting apparatus 1 equipped with the recording head 5 having such an actuator 75 as well, as described in the first to fourth embodiments, the pressure chamber 33 is highly integrated and the recording head 5 is downsized. The piezoelectric layer 20 positioned in the pressure chamber region 33a is not prevented from changing its shape by the applied voltage.

  Since the other configuration of the actuator 75 is the same as the configuration of the actuator 16 described in the first embodiment, the description thereof is omitted by attaching the same reference numerals to the corresponding configurations.

[Types of liquid conductive material]
By the way, as the liquid conductive material 50 provided in each of the actuators 16, 60, 65, 70, 75 described above, a known material having a predetermined fluidity and a predetermined conductivity when these actuators 16 are used is employed. Can do.

  For example, a conductive adhesive used for supporting a crystal resonator can be used as the liquid conductive material 50. As such a conductive adhesive, an epoxy resin or a polyimide resin, more preferably from the viewpoint of ensuring fluidity, a silicon resin is preferably used as a base material (also referred to as a binder), and gold, silver, copper, Some have kneaded a conductive filler made of metal powder such as nickel, aluminum, carbon, graphite. In addition, as a commercial product, among the 3300 series manufactured by Three Bond Co., Ltd., the liquid type and the dotite series manufactured by Fujikura Kasei Co., Ltd. can be used.

  It is also possible to use a low melting point ionic liquid. Ionic liquids have characteristics that vapor pressure is almost zero, flame retardancy, low viscosity and high conductivity, and there are imidazolium-based, biridinium-based, and aliphatic-based ones. Examples of imidazolium-based ionic liquids include AEImBr, AEImBF4, AEImTFSI, ABImBr, ABImBF4, ABImTFSI, AAImBr, AAImBF4, and AAImTFSI manufactured by Kanto Chemical Co., Ltd. ) As a commercial product. Examples of the aliphatic ionic liquid include TMPA TFSI, PP13 TFSI, P13 TFSI, and P14 TFSI manufactured by Kanto Chemical Co., Ltd.

  In addition, a known conductive polymer (for example, Baytron PEDOT manufactured by TA Chemical Co., Ltd.), galinstan, which is a liquid metal at room temperature, or the like can be used.

  Which material is used as the liquid conductive material 50 depends on the flow characteristics within the temperature range of the actuators 16, 60, 65, 70, 75 when the liquid ejection apparatus 1 is used (in other words, the curing characteristics). In addition, the volume resistivity (Ωcm) of each material itself, the contact resistance (mΩ) with the drive electrode 41 and the power feeding electrodes 46, 71, 76 in contact with the liquid conductive material 50, etc. Good.

  In the first to fifth embodiments described above, the first through-hole 42a and the second through-hole 47a have been described as having rhombuses, but the present invention is not limited to this, and other shapes can be employed. Further, the first through hole 42a and the second through hole 47a do not have to have all of the opening regions in the pressure chamber region 33a, and may have a partially overlapping configuration in plan view. Similarly, the drive electrode 41 and the power supply electrodes 46, 71, and 76 (particularly, the bump 46c, the solder bump 72, and the spiral contact 77) do not have to be configured to exist only in the pressure chamber region 33a. The structure which overlapped partially by vision may be sufficient.

  The bumps 46c, the solder bumps 72, and the spiral contacts 77 ensure the connection between the power supply electrodes 46, 71, and 76 and the liquid conductive material 50 due to their presence. If the electrodes 46, 71, 76 and the drive electrode 41 are connected via the liquid conductive material 50, the lower surfaces of the power supply electrodes 46, 71, 76 may be flat.

  Further, all of the actuators 16, 60, 65, 70, 75 described above are of a so-called unimorph type, but can also be applied to a bimorph type. For example, when a bimorph actuator is disposed in place of the actuators 16, 60, 65, 70, 75, among the plurality of electrodes of the bimorph actuator, the bimorph actuator is positioned at the extreme end opposite to the pressure chamber 33 side. The connection form of the drive electrode 41 and the power feeding electrodes 46, 71, 76 described above can be applied to the electrical connection between the electrode and the power feeding electrode.

  The present invention provides a liquid ejection device capable of appropriately changing the shape of a piezoelectric layer while realizing a reduction in size of a flow path unit and an improvement in resolution of an image formed by the ejection liquid, and the liquid ejection device It can be applied to the manufacturing method.

1 is a schematic perspective view of a liquid ejection apparatus according to Embodiment 1 of the present invention. FIG. 2 is a schematic plan view when the recording head shown in FIG. 1 is viewed from above. FIG. 3 is a schematic plan view showing an enlarged part of the recording head shown in FIG. 2. FIG. 4 is a schematic cross-sectional view when the recording head shown in FIG. 3 is cut along line IV-IV. It is a bottom view which shows the structure of a feed electrode. It is drawing which shows the manufacturing method of an actuator, (a)-(d) has shown the 1st process-the 4th process, respectively. It is drawing which shows the manufacturing method of an actuator, (a)-(d) has shown the 5th process-the 8th process, respectively. FIG. 10 is a partial cross-sectional view illustrating a configuration of an actuator included in a liquid ejection device according to Embodiment 2. FIG. 6 is a diagram illustrating a configuration of an actuator included in a liquid ejection device according to Embodiment 3, where (a) illustrates a partial cross-sectional view and (b) illustrates a plan view of a first insulating layer. FIG. 10 is a partial cross-sectional view illustrating a configuration of an actuator provided in a liquid ejection device according to a fourth embodiment. FIG. 9 is a partial cross-sectional view illustrating a configuration of an actuator provided in a liquid ejection device according to a fifth embodiment. It is a bottom view which shows the structure of a spiral contactor.

DESCRIPTION OF SYMBOLS 1 Liquid ejection apparatus 5 Recording head 15 Flow path unit 16, 60, 65, 70, 75 Actuator 16a Chip-on film 16b Drive layer 20 Piezoelectric layer 20a Contact area 21a Pressure chamber hole 24a Nozzle hole 30 Liquid flow path 33 Pressure chamber 33a Pressure Chamber region 40 Common electrode 41 Drive electrode 42 First insulating layer 42a First through hole 42b Open surface 46, 71, 76 Feed electrode 46c Bump 47 Second insulating layer 47a Second through hole 48 Adhesive 50 Liquid conductive material 51 Accommodating space 51a Surplus space 60a Contact area 72 Solder bump 77 Spiral contact

Claims (9)

A pressure chamber provided in the middle of a liquid flow path leading to the discharge port to discharge liquid from the discharge port due to a volume change, a piezoelectric layer that changes the volume of the pressure chamber, and an electrical connection to the piezoelectric layer And a power supply electrode for applying a voltage thereto,
The piezoelectric layer can be deformed by an applied voltage, is provided so that one surface faces the pressure chamber, and the other surface and the power feeding electrode are electrically connected by a liquid conductive material. ,
Further the other surface of the piezoelectric layer have a contact area as the electrical contact between the liquid electroconductive material in the region occupied by the pressure chamber in the thickness direction when viewed,
The liquid ejecting apparatus according to claim 1, wherein the liquid conductive material has predetermined fluidity that does not prevent deformation of the piezoelectric layer when the piezoelectric layer is deformed and driven by an applied voltage . A driving electrode is joined to the other surface of the piezoelectric layer so as to at least partially overlap the contact region. The piezoelectric layer and the feeding electrode are electrically connected to each other by a liquid conductive material via the driving electrode. The liquid ejecting apparatus according to claim 1, wherein the liquid ejecting apparatus is connected to each other. Between the contact region and the feed electrode in the piezoelectric layer, a liquid discharge according to claim 1, characterized in that a liquid-tight manner a conductive material accommodation space for accommodating the liquid electroconductive material are formed apparatus. The first insulating layer is further provided on the other surface of the piezoelectric layer, and the first insulating layer is formed with a first through hole that exposes the contact region and constitutes the conductive material accommodating space. The liquid ejection device according to claim 3 , wherein the liquid ejection device is a liquid ejection device. A wiring board having the power supply electrode;
The wiring board includes a base material provided with the power supply electrode on one surface, a wiring provided on the one surface of the base material in electrical connection with the power supply electrode, and the base material. A second insulating layer covering the wiring above,
The second insulating layer has a second through hole that partially exposes a surface of the power supply electrode facing the contact region,
By connecting the first insulating layer and the second insulating layer, the first through hole and the second through hole communicate with each other to form the conductive material accommodation space. The liquid ejection apparatus according to claim 4 . 6. The liquid ejection apparatus according to claim 4 , wherein the power supply electrode includes a bump protruding toward the piezoelectric layer side from an opening surface of the first through hole of the first insulating layer. The liquid ejecting apparatus according to claim 6 , wherein the bump includes a press bump formed by pressing the power supply electrode, a solder bump formed by soldering the power supply electrode, or a spiral contact. The liquid ejection device according to claim 3, wherein the conductive material accommodation space has a surplus volume in addition to the accommodation volume of the liquid conductive material. Wherein the peripheral vicinity of the first the first through-hole in which the insulating layer has, 4 through claim, characterized in that receiving recess capable of the liquid electroconductive material leaking from the first through hole is formed The liquid ejection device according to any one of 8 .

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