JP2020059291A - Liquid jet device and piezoelectric actuator - Google Patents

Abstract

To realize moisture proof of a piezoelectric device without adding a dedicated member specially.SOLUTION: A plurality of connection terminals 50 are arranged in a peripheral region of a plurality of piezoelectric devices 41 on one surface of a channel unit 20. A driver IC 46 is arranged facing to the one surface of the channel unit 20 so as to cover the plurality of piezoelectric devices 41. The driver IC 46 is connected with the plurality of connection terminals 50 via a plurality of bumps 51, thus the plurality of piezoelectric devices 41 are surrounded by the plurality of bumps 51. In addition, an insulating sealing member 52 is filled between the plurality of bumps 51. Thus, the plurality of piezoelectric devices 41 are sealed by the driver IC 46, the plurality of bumps 51, and the sealing member 52 between the plurality of bumps 51, and the plurality of piezoelectric devices 41 are insulated from an atmosphere.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a liquid ejecting apparatus and a piezoelectric actuator.

  2. Description of the Related Art Conventionally, there is known a liquid ejecting apparatus having a piezoelectric actuator that applies ejection energy to a liquid. For example, Patent Document 1 discloses an inkjet head including a flow path forming substrate in which a plurality of pressure chambers that communicate with a plurality of nozzles are formed, and a piezoelectric actuator provided in the flow path forming substrate. There is.

  The piezoelectric actuator has a plurality of piezoelectric elements arranged on the surface of an elastic film covering the plurality of pressure chambers so as to face the plurality of pressure chambers. The piezoelectric element has a piezoelectric layer, an upper electrode film and a lower electrode film. The piezoelectric layer is formed on the surface of an elastic film made of silicon dioxide by a film forming technique such as a sol-gel method or a MOD method.

  By the way, in the above-mentioned piezoelectric actuator, it is preferable that the piezoelectric layer is thin from the viewpoint of further improving the driving efficiency of the piezoelectric element and realizing high-speed driving. However, as the piezoelectric layer becomes thinner, the electric field applied to the piezoelectric layer becomes stronger, and when the piezoelectric layer absorbs moisture in the atmosphere, a large leak current occurs between the electrode films, causing dielectric breakdown. There is a risk of reaching. Therefore, it is required to shield the piezoelectric element from the atmosphere to prevent moisture. In the ink jet head of Patent Document 1, a moisture-resistant protective film that individually covers a plurality of piezoelectric elements is formed on the flow path forming substrate to prevent the piezoelectric elements from contacting the atmosphere.

JP 2001-138511 A

  In the piezoelectric actuator of Patent Document 1, after forming a plurality of piezoelectric elements, it is necessary to separately form a moisture-proof protective film so as to cover the plurality of piezoelectric elements. As a result, the number of members that make up the piezoelectric actuator increases and the number of extra steps increases, resulting in an increase in manufacturing cost.

  An object of the present invention is to realize moisture proofing of a piezoelectric element without adding any special member.

A liquid ejecting apparatus according to a first aspect of the invention is a flow channel structure in which a liquid flow channel including a plurality of nozzles and a plurality of pressure chambers communicating with the plurality of nozzles is formed, and one surface of the flow channel structure. And a plurality of piezoelectric elements arranged to face the plurality of pressure chambers, and a driver IC for driving the plurality of piezoelectric elements,
A plurality of connection terminals including a plurality of drive terminals respectively connected to the plurality of piezoelectric elements are arranged on the one surface of the flow path structure in a peripheral region of the plurality of piezoelectric elements, and the driver IC is provided. Are arranged so as to face the one surface of the flow path structure so as to cover the plurality of piezoelectric elements, and a plurality of bumps protruding to the other side of the driver IC and the flow path structure. Is provided, and the plurality of first bumps included in the plurality of bumps connect the driver IC and the plurality of connection terminals arranged in the peripheral region of the plurality of piezoelectric elements to each other. The piezoelectric element is surrounded by the plurality of first bumps, and an insulating sealing material is filled between the plurality of first bumps.

  In the present invention, the driver IC is arranged on one surface of the flow path structure so as to cover the plurality of piezoelectric elements. Then, when the driver IC and the plurality of connection terminals formed in the peripheral area of the piezoelectric element on the one surface of the flow path structure are connected by the plurality of first bumps, the plurality of first bumps form a plurality of connection terminals. The piezoelectric element will be surrounded. Furthermore, an insulating sealing material is filled between the plurality of first bumps. Thereby, the plurality of piezoelectric elements are sealed by the driver IC, the plurality of first bumps, and the sealing material between the plurality of first bumps, and the plurality of piezoelectric elements are shielded from the atmosphere. As described above, since the plurality of piezoelectric elements are covered by using the driver IC and the bumps for connecting the driver IC to the plurality of connection terminals on the flow path structure side, a dedicated member is added to add components. The piezoelectric element can be shielded from the atmosphere to prevent moisture without increasing the number of points.

  In the liquid ejecting apparatus of a second invention, in the first invention, the connection terminal is arranged outside an area of the one surface of the flow channel structure facing the pressure chamber. It is a feature.

  When the driver IC is pressed against the flow path structure and connected to the plurality of connection terminals, the part to be pressed on the flow path structure side does not face the pressure chamber, and therefore the pressing force can be endured. Further, the flow path structure is less likely to bend during joining, and the piezoelectric element is prevented from being damaged by the flexure of the flow path structure.

  In the liquid ejecting apparatus of a third aspect of the present invention, in the second aspect of the present invention, the bump is bonded to a region of the one surface of the flow path structure that faces a partition wall partitioning the plurality of pressure chambers. It is characterized by being present.

  Since the driver IC is pressed through the bumps even in the region where the plurality of pressure chambers are arranged, the driver IC can be strongly pressed against the flow path structure to be reliably bonded. Further, if the driver IC is pressed only to the peripheral region of the plurality of piezoelectric elements, the flow channel structure may be warped to the driver IC side in the inner region (piezoelectric element arrangement region). In the present invention, the pressing force also acts on the inner region of one surface of the flow path structure, so that warpage is prevented.

  A liquid ejecting apparatus according to a fourth invention is the liquid ejecting apparatus according to any one of the first to third inventions, wherein the plurality of pressure chambers are arranged in a predetermined direction along the one surface of the flow path structure, and the driver is provided. The IC has a rectangular planar shape and is arranged to face the one surface of the flow channel structure in a state where its long side is along the predetermined direction, and the IC of the one surface of the flow channel structure is The plurality of driving terminals are arranged in a region along the long side of the driver IC among the peripheral regions of the plurality of piezoelectric elements, and the plurality of piezoelectric elements on the one surface of the flow path structure. The connection terminals other than the drive terminals are arranged in a region along the short side of the driver IC in the peripheral region of the element.

  When the planar shape of the driver IC is rectangular, a plurality of driving terminals respectively corresponding to a plurality of pressure chambers (a plurality of piezoelectric elements) are arranged along the long side thereof, so that the length to be sealed is increased. It is possible to reliably seal the long side having a large gap. On the other hand, since the short side of the driver IC can be sealed with a smaller number of bumps than the long side, connection terminals other than the drive terminals are arranged on the short side.

  A liquid ejecting apparatus according to a fifth aspect of the present invention is the liquid ejecting apparatus according to any one of the first to fourth aspects, wherein the plurality of bumps further includes a second bump disposed between the plurality of first bumps. The second bump is bonded to a region of the one surface of the flow path structure where the connection terminal is not arranged, and the sealing material is filled between the first bump and the second bump. It is characterized by that.

  The first bumps electrically connect the driver IC and the connection terminal on the side of the flow path structure and contribute to driving the piezoelectric element. Therefore, the number and spacing of the first bumps depend on the size of the piezoelectric element. It may not be possible to freely set it due to restrictions such as the number of sheaths. However, if the distance between the first bumps is large, it becomes difficult to hold the encapsulant between the adjacent first bumps, which makes encapsulation difficult. In this respect, according to the present invention, a so-called dummy second bump, which is joined to a region where the connection terminal is not arranged, is arranged between the plurality of first bumps. Accordingly, even if the distance between the first bumps adjacent to each other is wide, the distance between the bumps can be narrowed by disposing the second bumps between them, so that the space between the bumps can be surely secured by the sealing material. It can be sealed.

A piezoelectric actuator according to a sixth aspect of the present invention includes a plurality of piezoelectric elements arranged on one surface of a substrate and a driver IC that drives the plurality of piezoelectric elements.
On the one surface of the substrate, a plurality of connection terminals including a plurality of driving terminals respectively connected to the plurality of piezoelectric elements are arranged in a peripheral region of the plurality of piezoelectric elements, and the driver IC is A plurality of bumps, which are arranged to face the one surface of the substrate so as to cover a plurality of piezoelectric elements, are provided with one of the driver IC and the flow path structure, and a plurality of bumps projecting to the other side thereof are provided. The plurality of first bumps included in the bumps connect the driver IC and the plurality of connection terminals arranged in the peripheral region of the plurality of piezoelectric elements, so that the plurality of piezoelectric elements are connected to the driver. It is characterized in that it is surrounded by an IC and the plurality of first bumps, and an insulating sealing material is filled between the plurality of first bumps.

  In the piezoelectric actuator of the present invention, the plurality of piezoelectric elements are sealed by the driver IC, the plurality of first bumps, and the sealing material between the plurality of first bumps. This makes it possible to shield the piezoelectric element from the atmosphere and prevent moisture without increasing the number of parts by adding a dedicated member.

  According to the present invention, the plurality of piezoelectric elements are sealed by the driver IC, the plurality of first bumps, and the sealing material between the plurality of first bumps. As described above, since a plurality of piezoelectric elements can be covered by using the driver IC and the bumps for connecting the driver IC to the plurality of connection terminals on the flow path structure side, a dedicated member is added. The piezoelectric element can be shielded from the atmosphere to prevent moisture without increasing the number of parts.

It is a schematic plan view of the inkjet printer of the present embodiment. It is a top view of an inkjet head. FIG. 3 is a plan view of an inkjet head (a state in which a driver IC is not attached). FIG. 4 is a sectional view taken along line IV-IV in FIG. 2. FIG. 5 is a sectional view taken along line VV of FIG. 2. It is a top view of the inkjet head which concerns on a modification. FIG. 7 is a sectional view taken along line VII-VII of FIG. 6. It is a top view of the inkjet head which concerns on another modification. It is a top view of the inkjet head which concerns on another modification. FIG. 10 is a sectional view taken along line XX of FIG. 9. It is a top view of the inkjet head which concerns on another modification. FIG. 9 is a plan view of an inkjet head (state in which a driver IC is not attached) according to another modification.

  Next, an embodiment of the present invention will be described. FIG. 1 is a schematic plan view of the inkjet printer of this embodiment. First, a schematic configuration of the inkjet printer 1 will be described with reference to FIG. In the following description, the front side of the paper of FIG. 1 is defined as the upper side and the other side of the paper is defined as the lower side, and the direction words “upper” and “lower” are used as appropriate for description. As shown in FIG. 1, the inkjet printer 1 includes a platen 2, a carriage 3, an inkjet head 4, a transport mechanism 5, and the like.

  A recording sheet 100, which is a recording medium, is placed on the upper surface of the platen 2. Further, above the platen 2, two guide rails 10 and 11 extending parallel to the left-right direction (scanning direction) of FIG. 1 are provided. The carriage 3 is configured to be capable of reciprocating in the scanning direction along the two guide rails 10 and 11 in the area facing the platen 2. Further, an endless belt 14 wound around two pulleys 12 and 13 is connected to the carriage 3, and when the carriage drive motor 15 drives the endless belt 14 to travel, the carriage 3 moves to the endless belt. It moves in the scanning direction as the vehicle travels 14.

  The inkjet head 4 (liquid ejecting apparatus) is attached to the carriage 3 and moves in the scanning direction together with the carriage 3. The inkjet head 4 is connected to an ink cartridge (not shown) attached to the printer 1 by a tube. Further, a plurality of nozzles 16 are formed on the lower surface of the inkjet head 4 (the surface on the other side of the paper surface of FIG. 1). Then, the inkjet head 4 ejects the ink supplied from the ink cartridge from the plurality of nozzles 16 onto the recording paper 100 placed on the platen 2.

  The transport mechanism 5 has two transport rollers 18 and 19 arranged so as to sandwich the platen 2 in the transport direction, and these two transport rollers 18 and 19 are rotationally driven by a motor (not shown). The transport mechanism 5 transports the recording paper 100 placed on the platen 2 in the transport direction by the two transport rollers 18 and 19.

  The inkjet printer 1 ejects ink onto the recording paper 100 placed on the platen 2 from an inkjet head 4 that reciprocates in the scanning direction (the left-right direction in FIG. 1) together with the carriage 3. At the same time, the recording paper 100 is transported in the transport direction (downward in FIG. 1) by the two transport rollers 18 and 19. An image, a character, etc. are recorded on the recording sheet 100 by the above operation.

  Next, the inkjet head 4 will be described. FIG. 2 is a plan view of the inkjet head. Further, FIG. 3 is a plan view of the inkjet head in a state where the driver IC shown in FIG. 2 is not attached. FIG. 4 is a sectional view taken along line IV-IV in FIG. In addition, in FIG. 4, the ink filled in the ink flow path is indicated by a symbol “I”. As shown in FIGS. 2 to 4, the inkjet head 4 includes a flow path unit 20 (flow path structure), a piezoelectric actuator 21, a driver IC 46, and the like.

  As shown in FIG. 4, the flow path unit 20 has a structure in which five plates 30 to 34 each having a large number of flow path forming holes are stacked. An ink channel as described below is formed in the channel unit 20 by communicating a number of channel forming holes when these five plates 30 to 34 are stacked. The material of the five plates 30 to 34 is not particularly limited, but may be, for example, a metal plate such as stainless steel or nickel alloy steel. Alternatively, it may be a silicon single crystal substrate.

  As shown in FIG. 2, an ink supply hole 26 connected to an ink cartridge (not shown) is formed on the upper surface of the flow path unit 20. Inside the flow path unit 20, two manifolds 25 each extending in the transport direction are formed. The two manifolds 25 are commonly connected to one ink supply hole 26, and the ink supplied from the ink cartridge is supplied to each of the two manifolds 25.

  Further, as shown in FIGS. 2 to 4, the flow path unit 20 communicates with the plurality of nozzles 16 formed in the nozzle plate 34 of the lowermost layer and opening to the lower surface of the flow path unit 20, and the plurality of nozzles 16, respectively. It has a plurality of pressure chambers 24. As shown in FIGS. 2 and 3, on the lower surface of the flow path unit 20 (the surface on the other side of the paper surface of FIGS. 2 and 3), the plurality of nozzles 16 are arranged in two rows along the transport direction. The arrangement of the plurality of nozzles 16 is a so-called staggered arrangement in which the positions of the nozzles 16 in the left and right two nozzle rows are displaced from each other in the transport direction.

  Each of the plurality of pressure chambers 24 has a substantially elliptical planar shape that is long in the scanning direction. The plurality of pressure chambers 24 are arranged in a plane, and the plurality of pressure chambers 24 are covered with a diaphragm 30 from above. In addition, the plurality of pressure chambers 24 are arranged in two rows in a zigzag pattern along the carrying direction, corresponding to the plurality of nozzles 16, respectively. Each pressure chamber 24 communicates with the corresponding nozzle 16 at one longitudinal end thereof. The arrangement relationship between the pressure chambers 24 and the nozzles 16 is reversed between the left and right two pressure chamber rows. That is, as shown in FIGS. 2 to 4, in the pressure chamber row on the left side, the nozzles 16 corresponding to the right end portion in the longitudinal direction of each pressure chamber 24 communicate with each other. On the other hand, in the pressure chamber row on the right side, the nozzles 16 corresponding to the left end portions in the longitudinal direction of the pressure chambers 24 communicate with each other. As a result, as shown in FIGS. 2 and 3, two nozzle rows corresponding to the respective pressure chamber rows are arranged inside the two pressure chamber rows.

  The two rows of pressure chambers are arranged at positions overlapping the two manifolds 25, respectively, and each pressure chamber 24 communicates with the manifold 25 located immediately below. As a result, as shown in FIG. 4, the flow path unit 20 is formed with a plurality of individual ink flow paths 27 that branch from the manifold 25 and reach the nozzles 16 via the pressure chambers 24.

  Next, the piezoelectric actuator 21 will be described. The piezoelectric actuator 21 is arranged on the upper surface of the diaphragm 30 of the flow path unit 20. As shown in FIGS. 2 to 4, the piezoelectric actuator 21 includes a piezoelectric body 40, a plurality of drive electrodes 42, and a common electrode 43.

  As shown in FIG. 4, an insulating film 44 made of an insulating material such as a synthetic resin material is formed on almost the entire upper surface of the diaphragm 30. Two piezoelectric bodies 40 formed in a rectangular shape are arranged on the upper surface of the diaphragm 30 covered with the insulating film 44. The two piezoelectric bodies 40 are arranged such that their longitudinal directions are parallel to the arrangement direction (conveyance direction) of the pressure chambers 24 so as to respectively cover the two pressure chamber rows. The piezoelectric body 40 is made of a piezoelectric material containing ferroelectric lead zirconate titanate (PZT) as a main component, which is a solid solution of lead titanate and lead zirconate. The piezoelectric body 40 can be directly formed on the upper surface of the diaphragm 30 covered with the insulating film 44 by a known film forming technique such as a sputtering method or a sol-gel method. Alternatively, it can also be formed by firing an unfired thin green sheet and then adhering it to the diaphragm 30.

  The plurality of drive electrodes 42 are formed on the lower surface of the piezoelectric body 40 in regions respectively facing the plurality of pressure chambers 24. Each drive electrode 42 has a substantially elliptical planar shape that is slightly smaller than the pressure chamber 24, and is arranged so as to face a substantially central portion of the corresponding pressure chamber 24. The drive electrode 42 is electrically insulated from the diaphragm 30 by the insulating film 44.

A plurality of drive terminals 45 are connected to the plurality of drive electrodes 42, respectively. Each drive terminal 45 is drawn out from the corresponding drive electrode 42 on the insulating film 44 toward the side opposite to the nozzle 16 (outer side) in the longitudinal direction to a region not facing the pressure chamber 24. 3, exposed from the piezoelectric body 40 as shown in FIG. The plurality of driving terminals 45 are arranged along the carrying direction on both sides of the two piezoelectric bodies 40 in the scanning direction. A driver IC 46 described later is connected to the plurality of drive terminals 45, and a predetermined drive voltage is applied from the driver IC 46 to each of the plurality of drive electrodes 42.

  The common electrode 43 is formed across the two piezoelectric bodies 40 so as to cover the entire upper surface of the piezoelectric bodies 40. In FIG. 3, the common electrode 43 that covers the two piezoelectric bodies 40 is hatched. Specifically, the common electrode 43 has two electrode portions 43a respectively formed on the entire upper surfaces of the two piezoelectric bodies 40, and one side in the arrangement direction of the pressure chambers 24 (the upstream side in the transport direction) from the two electrode portions 43a. It has a first connecting portion 43b that is drawn out and formed on the upper surface of the diaphragm 30, and a second connecting portion 43c that is formed on the upper surface of the diaphragm 30 in a region between the two piezoelectric bodies 40.

  The first connection portion 43b extends in the scanning direction along the short sides of the two rectangular piezoelectric bodies 40. The second connecting portion 43c extends in the carrying direction along the long sides of the two rectangular piezoelectric bodies 40. The first connecting portion 43b and the second connecting portion 43c are electrically insulated from the diaphragm 30 by the insulating film 44. Further, since the first connecting portion 43b and the second connecting portion 43c are both formed on the upper surface of the vibration plate 30, they are located lower than the two electrode portions 43a formed on the upper surface of the piezoelectric body 40. As shown in the cross section of FIG. 4, the common electrode 43 has a locally recessed shape in the second connection portion 43c. The first connecting portion 43b is located on the upper surface of the vibration plate 30 on the upstream side in the transport direction with respect to the region where the plurality of pressure chambers 24 are formed. The second connecting portion 43c faces the partition wall portion 20a of the flow path unit 20 that separates the two rows of the pressure chambers 24. That is, both the first connecting portion 43b and the second connecting portion 43c are arranged on the upper surface of the diaphragm 30 in a region that does not face the pressure chamber 24.

  The first connecting portion 43b located upstream of the two piezoelectric bodies 40 in the transport direction and the second connecting portion 43c located between the two piezoelectric bodies 40 are both connected to a driver IC 46 to be described later. Conducts with the ground wiring. As a result, the common electrode 43 is always held at the ground potential.

  As shown in FIG. 4, a portion (hereinafter, also referred to as “piezoelectric element 41”) of the piezoelectric body 40, which is sandwiched between one drive electrode 42 and the electrode portion 43a of the common electrode 43, will be described below. When the drive voltage is applied to the drive electrode 42, the drive electrode 42 is deformed and becomes a portion that applies ejection energy to the ink in one pressure chamber 24. In the present embodiment, one piezoelectric body 40 is arranged over a plurality of pressure chambers 24 belonging to one pressure chamber row, so that a plurality of piezoelectric elements 41 corresponding to one pressure chamber row are integrated. It has been configured. Further, each of the plurality of piezoelectric elements 41 is polarized in the thickness direction.

  When the drive voltage is applied from the driver IC 46 to the drive electrode 42, a potential difference is generated between the drive electrode 42 and the common electrode 43 having the ground potential, and the portion of the piezoelectric body 40 between these two electrodes 42, 43. An electric field in the thickness direction acts on (piezoelectric element 41). Since the direction of this electric field is parallel to the polarization direction of the piezoelectric element 41, the piezoelectric element 41 expands in the thickness direction and contracts in the surface direction. Due to the contraction of the piezoelectric element 41, the vibration plate 30 covering the pressure chamber 24 is bent so as to be convex toward the pressure chamber 24, and the volume of the pressure chamber 24 is reduced. At that time, pressure (jetting energy) is applied to the ink in the pressure chamber 24, and ink droplets are jetted from the nozzle 16.

  Next, the driver IC 46 will be described. Various circuits for driving the piezoelectric actuator are incorporated in the driver IC 46. As shown in FIG. 2, the driver IC 46 has a rectangular planar shape. The driver IC 46 is arranged so as to face the upper surface of the vibration plate 30 of the flow path unit 20 with its long side along the arrangement direction of the pressure chambers 24, and covers the two piezoelectric bodies 40 from above. It is joined to the diaphragm 30.

  As described above, a plurality of drive terminals 45, which are drawn out from a plurality of drive electrodes 42, are arranged in regions on both sides of the upper surface of the diaphragm 30 in the scanning direction of the two piezoelectric bodies 40. . Further, the first connection portion 43b of the common electrode 43 is arranged in a region on the upper surface of the vibration plate 30 upstream of the two piezoelectric bodies 40 in the transport direction. Further, as shown in FIGS. 2 and 3, a plurality of input terminals 47 (power input terminal 47a, ground input terminal 47b, signal input terminal 47c) are provided in a region downstream of the two piezoelectric bodies 40 in the transport direction. They are arranged side by side. The plurality of input terminals 47 are connected to a control board (not shown) that controls the operation of the inkjet head 4.

  That is, the plurality of driving terminals 45, the first connecting portion 43b of the common electrode 43, and the plurality of input terminals 47 are formed on the upper surface of the diaphragm 30 in the peripheral region of the two piezoelectric bodies 40. In addition, the second connection portion 43c of the common electrode 43 is arranged on the upper surface of the diaphragm 30 in a region between the two piezoelectric bodies 40. Hereinafter, for convenience of description, the plurality of driving terminals 45, the first connecting portion 43b, the second connecting portion 43c of the common electrode 43, and the plurality of input terminals 47 are collectively referred to as "a plurality of connecting terminals 50".

  On the other hand, on the lower surface (connection surface) of the driver IC 46 facing the vibration plate 30, a plurality of bumps 51 made of a conductive material and connected to the above-described plurality of connection terminals 50 are formed below (on the surface of FIG. 2). It is provided so as to project to the other side). First, as shown in FIG. 2, a plurality of drive bumps 51a connected to a plurality of drive terminals 45 are provided at two edge portions along the two long sides 46a and 46b of the rectangular driver IC 46, respectively. ing. A plurality of first common electrode bumps 51b connected to the first connection portions 43b of the common electrode 43 are provided on an edge portion along one short side 46c of the driver IC 46. A plurality of input bumps 51c that are respectively connected to the plurality of input terminals 47 are provided on the edge portion along the other short side 46d of the driver IC 46. Further, a plurality of second common electrode bumps 51d connected to the second connection portions 43c of the common electrode 43 are also provided in the central portion of the driver IC 46.

  The driver IC 46 is arranged on the upper surface of the diaphragm 30 with its long sides 46a and 46b parallel to the transport direction, and the plurality of bumps 51 described above are connected to the plurality of connections formed on the upper surface of the diaphragm 30. It is connected to each terminal 50. The driver IC 46 is connected to the control board via the plurality of input terminals 47 (power input terminal 47a, ground input terminal 47b, signal input terminal 47c), thereby supplying power from the control board side, ground connection, and A control signal is input. In addition, the driver IC 46 is connected to the plurality of drive electrodes 42 via the plurality of drive terminals 45 and is also connected to the common electrode 43. As a result, the driver IC 46 applies the drive voltage individually to the plurality of drive electrodes 42 while maintaining the common electrode 43 at the ground potential.

  Here, as shown in FIGS. 2 and 3, among the plurality of bumps 51 provided in the driver IC 46, the bumps 51a, 51b, 51c provided along the entire circumference of the edge portion of the driver IC 46 (the present invention). The two piezoelectric bodies 40 (the plurality of piezoelectric elements 41) are surrounded by the first bumps (1). FIG. 5 is a sectional view taken along line VV of FIG. As shown in FIGS. 4 and 5, a sealing material 52 made of an insulating material such as synthetic resin is filled between the plurality of bumps 51 connecting the driver IC 46 and the plurality of connection terminals 50. As a result, the adjacent bumps 51 are insulated from each other and the gaps between the bumps 51 are completely sealed. Therefore, the plurality of piezoelectric elements 41 are hermetically sealed by the driver IC 46, the plurality of bumps 51a, 51b, 51c (first bumps) and the sealing material 52 between the plurality of bumps 51a, 51b, 51c, and shielded from the atmosphere. To be done.

  The electric connection between the driver IC 46 and the plurality of connection terminals 50 on the diaphragm 30 side is performed, for example, as follows. First, a plurality of anisotropic conductive materials such as anisotropic conductive film (ACF) and anisotropic conductive paste (ACP), which are conductive particles dispersed in a thermosetting resin, are formed on the upper surface of diaphragm 30. It is arranged so as to cover the connection terminal 50 of. Next, the driver IC 46 is pressed against the diaphragm 30 while heating the flow path unit 20. At this time, a large pressure is locally applied to the anisotropic conductive material between the bump 51 on the driver IC 46 side and the connection terminal 50, and the thermosetting resin is laterally pushed out, and the bump 51 is left by the conductive particles remaining. And the connection terminal 50 become conductive. At the same time, the thermosetting resin is cured by heating, and the driver IC 46 and the flow path unit 20 are mechanically joined. In addition, almost no pressure acts on the portion of the anisotropic conductive material where the bump 51 is not pressed, and the insulating property is maintained. In the present embodiment, when the driver IC 46 is pressed, the anisotropic conductive material that has entered between the adjacent bumps 51 functions as the above-mentioned sealing material 52 that insulates the bumps 51 and seals the gap. To do.

  Further, the bumps 51 on the driver IC 46 side and the connection terminals 50 on the flow path unit 20 side may be joined by solder. In this case, after solder bonding, a sealing material 52 made of a liquid curable resin such as an epoxy resin is injected between the bumps 51 and cured.

  As described above, in the present embodiment, a plurality of piezoelectric elements are used by using the driver IC 46 that drives the piezoelectric actuator 21 and the bumps 51 that connect the driver IC 46 to the plurality of connection terminals 50 on the flow path unit 20 side. 41 is covered and is shielded from the atmosphere. Therefore, the plurality of piezoelectric elements 41 can be reliably protected against moisture without adding a dedicated member to increase the number of parts.

  In addition, as shown in FIGS. 2 to 4, a plurality of connection terminals 50 on the diaphragm 30 side (a plurality of drive terminals 45, a first connection portion 43b of the common electrode 43, a second connection portion 43c, and a plurality of connection terminals 50). The input terminal 47) is formed outside the region of the diaphragm 30 facing the pressure chamber 24. Therefore, when the driver IC 46 is pressed against the flow path unit 20 and joined to the plurality of connection terminals 50, the portion of the diaphragm 30 against which the plurality of bumps are pressed can withstand the pressing force. Further, therefore, the diaphragm 30 is less likely to bend when the driver IC 46 is joined, and the piezoelectric body 40 (piezoelectric element 41) is prevented from being damaged by the bending of the diaphragm 30.

  In addition, a second connecting portion 43c of the common electrode 43 is formed in a region of the diaphragm 30 that faces the partition wall portion 20a that separates the two rows of pressure chambers 24, and the second common electrode bump 51d is formed on the second connecting portion 43c. Are joined. That is, the driver IC 46 is pressed through the bumps 51d even in the region where the plurality of pressure chambers 24 are arranged, so that the driver IC 46 can be strongly pressed against the flow path unit 20 and can be reliably bonded. When the driver IC 46 is pressed only in the peripheral area of the piezoelectric body 40, the diaphragm 30 is warped upward (in the side of the driver IC 46) in the inner area (area where the piezoelectric body 40 is arranged). There is a risk that it will end up. On the other hand, in the present embodiment, the pressing force also acts on the inner region of the diaphragm 30, so that the warp is prevented.

  In order to reliably shield the piezoelectric body 40 from the atmosphere, it is necessary to completely seal the gaps between the bumps 51a, 51b, 51c (first bumps) surrounding the piezoelectric body 40 with the sealing material 52. However, if the gap between these bumps is large, it is difficult to hold the sealing material 52 and the sealing may be insufficient. In this regard, in the present embodiment, among the peripheral regions of the two piezoelectric bodies 40, the regions along the long sides 46a and 46b of the driver IC 46 correspond to the plurality of pressure chambers 24 (the plurality of drive electrodes 42), respectively. A large number of driving terminals 45 are arranged. As a result, it is possible to reliably seal the long side having a large length to be sealed. On the other hand, the short side of the driver IC 46 can be sealed with a smaller number of bumps than the long side. Therefore, the input terminals 47, which are smaller in number than the driving terminals 45, are arranged in the region along the one short side 46d of the driver IC 46 in the peripheral region of the piezoelectric body 40. Regarding the first connecting portion 43b arranged on the other short side 46c side of the driver IC 46, the number of the first common electrode bumps 51b does not need to be so large if only conduction with the driver IC 46 is considered. . However, from the viewpoint of ensuring the sealing of the short side 46c on the other side, it is preferable that the same number of the first common electrode bumps 51b as the plurality of input bumps 51c be provided.

  Next, a description will be given of a modified form in which various modifications are made to the above embodiment. However, components having the same configurations as those in the above-described embodiment are designated by the same reference numerals, and the description thereof will be appropriately omitted.

1] The arrangement of the plurality of connection terminals 50 connected to the driver IC 46 is not limited to a particular arrangement as long as at least some of the connection terminals 50 are arranged so as to surround the plurality of piezoelectric elements 41.

  For example, as shown in FIGS. 6 and 7, even if the driver IC 46 is connected to the common electrode 43 by the bump 51b only at the first connecting portion 43b formed on the upstream side of the two piezoelectric bodies 40 in the transport direction. Good. That is, the bump 51 may not be bonded to a region between the two piezoelectric bodies 40 that faces the partition wall portion 20 a that separates the pressure chamber 24.

  Alternatively, conversely, as shown in FIG. 8, the driver IC 46 may be connected to the common electrode 43 by the bump 51d only at the second connection portion 43c between the two piezoelectric bodies 40. In this case, on the short side 46c side of the driver IC 46, other connection terminals 50 other than those for connecting the common electrode 43, such as the plurality of input terminals 47, can be arranged.

  Further, in the above-described embodiment, as shown in FIG. 2, the plurality of drive terminals 45 are arranged on the long sides 46a and 46b of the driver IC 46, but when the number of connection terminals other than the drive terminals 45 is large. The driving terminal 45 may be arranged on the short side of the driver IC 46, and the connection terminals 50 other than the driving terminal 45 may be arranged on the long side of the driver IC 46.

2] In the above embodiment, the plurality of bumps 51 provided on the driver IC 46 are all electrically connected to the plurality of connection terminals 50 formed on the flow path unit 20 side. In addition, a so-called dummy bump that is joined to a region where the connection terminal 50 is not arranged may be included.

  For example, as shown in FIGS. 9 and 10, the driver IC 46 may be provided with dummy bumps 51e (second bumps) arranged between the plurality of drive bumps 51a. As shown in FIG. 10, the dummy bump is directly bonded to the insulating film 44 covering the diaphragm 30, and is not electrically connected to the connection terminal 50 such as the driving terminal 45. A sealing material 52 is filled between the drive bumps 51a and the dummy bumps 51e.

  The bumps 51 connected to the connection terminals 50, such as the drive bumps 51a, connect the driver IC 46 and the connection terminals 50 and contribute to the driving of the piezoelectric element 41. It may not be possible to freely set the elements 41 due to restrictions such as the size and number of the elements 41. However, if the distance between the bumps 51 is large, it becomes difficult to hold the sealing material 52 between the adjacent bumps 51, which makes sealing difficult. In this regard, in the configurations of FIGS. 9 and 10, since the dummy bumps 51e can be arranged between the plurality of drive bumps 51a to narrow the intervals between the bumps 51, the space between the adjacent bumps 51 is sealed by the sealing material 52. It can be surely sealed.

Further, in FIG. 9, the drive bumps 51a and the dummy bumps 51e are arranged on a straight line, but as shown in FIG. 11, the drive bumps 51a and the dummy bumps 51e are arranged at positions displaced in the scanning direction, These bumps 51 may be arranged in a staggered pattern. This arrangement is suitable when the arrangement interval of the drive bumps 51a is small and it is difficult to arrange the dummy bumps 51e between them. In addition, the thickness of the sealing material 52 held between the bumps 51 can be increased as compared with the configuration in which the drive bumps 51a and the dummy bumps 51e are arranged in a straight line (FIG. 9), and the sealing material 52 can be sealed accordingly. There is also an advantage that the stopping function is improved.

  Further, in the above-described embodiment (FIGS. 2 to 4), in the region of the vibration plate 30 facing the partition wall portion 20a that separates the two rows of pressure chambers from each other, the bumps (the second bumps) for conduction with the common electrode 43 are formed. Although the common electrode bumps 51d) are bonded, as described above, if the only purpose is to prevent the warp of the diaphragm 30, this bump need not be a bump for electrode conduction, but a dummy bump. May be

3] In the above-described embodiment, as shown in FIG. 3, one piezoelectric body 40 is disposed over a plurality of pressure chambers 24, so that a plurality of piezoelectric elements 41 respectively corresponding to the plurality of pressure chambers 24 are integrated. It was a simplified structure. On the other hand, as shown in FIG. 12, the plurality of piezoelectric elements 41 may be separated from each other and arranged in the central portions of the plurality of pressure chambers 24, respectively.

4] As understood from FIGS. 2 and 3 of the above-described embodiment, in order to cover the plurality of piezoelectric elements 41 with the driver IC 46, the size of the driver IC 46 is larger than the arrangement area of the plurality of piezoelectric elements 41. Must have a flat area. Conversely speaking, the maximum number of piezoelectric elements 41 (that is, the maximum number of nozzles 16) included in one head is restricted by the size of the driver IC 46. However, this does not mean that it becomes difficult to realize an inkjet head having a large number of nozzles 16 by applying the present invention. That is, by combining a plurality of head units as shown in FIGS. 2 and 3, it is possible to easily realize an inkjet head having more nozzles 16.

5] In the above-described embodiment, the driver IC 46 is provided with the plurality of bumps 51 that connect the driver IC 46 and the plurality of connection terminals 50. However, the plurality of bumps 51 are connected to the flow path unit 20 at the plurality of connections. The terminal 50 may be formed so as to project upward (to the driver IC 46 side).

  The above-described embodiment and its modifications are examples of applying the present invention to an inkjet head that is a liquid ejecting apparatus. However, the piezoelectric actuator of the present invention is not intended to be used for applying pressure to a liquid. Not limited. A plurality of piezoelectric elements are arranged on the substrate, and the plurality of piezoelectric elements are respectively driven by the driver IC to deform the substrate, thereby causing displacement and vibration of the plurality of solid objects to be driven. It may be one used for a purpose.

4 Inkjet Head 16 Nozzle 20 Flow Path Unit 20a Partition 21 Piezoelectric Actuator 24 Pressure Chamber 30 Vibration Plate 40 Piezoelectric Body 41 Piezoelectric Element 42 Drive Electrode 43 Common Electrode 43b First Connection 43c Second Connection 45 Drive Terminal 46 Driver IC
47 input terminal 50 connection terminal 51a drive bump 51b first common electrode bump 51c input bump 51d first common electrode bump 51e dummy bump 52 sealing material

Claims (5)

A flow channel structure in which a liquid flow channel including a plurality of nozzles and a plurality of pressure chambers respectively communicating with the plurality of nozzles is formed,
On one surface of the flow channel structure, a plurality of piezoelectric elements arranged respectively facing the plurality of pressure chambers,
Equipped with
On the one surface of the flow path structure, a plurality of connection terminals including a plurality of drive terminals respectively connected to the plurality of piezoelectric elements, are arranged in a peripheral region of the plurality of piezoelectric elements,
A plurality of bumps protruding from one surface of the flow path structure are provided,
By the plurality of bumps, by connecting the plurality of connection terminals arranged in the peripheral region of the plurality of piezoelectric elements, the plurality of piezoelectric elements are surrounded by the plurality of bumps,
The plurality of pressure chambers are arranged in a predetermined direction along the one surface of the flow channel structure,
The flow channel structure has a rectangular planar shape, the long side of which is arranged along the predetermined direction,
The head, wherein the plurality of drive terminals are arranged in a region along a long side of the one surface of the flow channel structure.   The head according to claim 1, wherein an insulating sealing material is filled between the plurality of bumps.   The head according to claim 1, wherein the connection terminals other than the drive terminals are arranged in a region along a short side of the one surface of the flow channel structure. The plurality of pressure chambers has two pressure chamber rows,
The head according to claim 1, wherein a plurality of bumps are arranged between the two rows of pressure chambers. The head is
A substrate for driving the plurality of piezoelectric elements,
The head according to claim 1, wherein the substrate is arranged to face the one surface of the flow channel structure.

Images