JP6658855B2 - Liquid ejection device and piezoelectric actuator - Google Patents

Description

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

  2. Description of the Related Art Conventionally, there has been known a liquid ejecting apparatus having a piezoelectric actuator for applying ejection energy to liquid. For example, Patent Literature 1 discloses an ink jet head having a flow path forming substrate in which a plurality of pressure chambers respectively communicating with a plurality of nozzles are formed, and a piezoelectric actuator provided in the flow path forming substrate. I have.

  The piezoelectric actuator has a plurality of piezoelectric elements arranged on a surface of an elastic film covering the plurality of pressure chambers, respectively, and opposed to 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 a 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-described piezoelectric actuator, it is preferable that the piezoelectric layer be 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 air, a large leak current is generated between the electrode films and dielectric breakdown occurs. There is a possibility of reaching. Therefore, it is required that the piezoelectric element be shielded 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 a flow path forming substrate, thereby preventing the piezoelectric elements from coming into contact with 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 each of the plurality of piezoelectric elements. As a result, the number of members constituting the piezoelectric actuator increases, and the number of extra steps increases, so that the manufacturing cost increases.

  An object of the present invention is to realize moisture proof of a piezoelectric element without specially adding a dedicated member.

A liquid ejecting apparatus according to a first aspect of the present invention includes a flow path structure in which a liquid flow path 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 path structure. A plurality of piezoelectric elements disposed opposite to the plurality of pressure chambers, respectively, 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 A plurality of bumps disposed 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. The driver IC is connected to the plurality of connection terminals arranged in the peripheral region of the plurality of piezoelectric elements by a plurality of first bumps included in the plurality of bumps. 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 region of the piezoelectric element on one surface of the flow path structure are connected by the plurality of first bumps, the plurality of first bumps cause the plurality of first bumps to connect to the plurality of connection terminals. The piezoelectric element will be surrounded. Further, 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 side of the flow path structure, a special member is added. The piezoelectric element can be shielded from the atmosphere to prevent moisture without increasing the score.

  According to a second aspect of the present invention, in the liquid ejecting apparatus according to the first aspect, the connection terminal is disposed outside a region of the one surface of the flow path 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 portion on the flow path structure side to be pressed does not face the pressure chamber, so that it can withstand the pressing force. In addition, the flow path structure is unlikely to be bent at the time of joining, and the piezoelectric element is prevented from being damaged due to the bending of the flow path structure.

  In the liquid ejecting apparatus according to a third aspect of the present invention, in the second aspect, the bump is also joined to a region of the one surface of the flow path structure facing a partition part separating the plurality of pressure chambers. It is characterized by having.

  Since the driver IC is pressed via the bumps even in the region where the plurality of pressure chambers are arranged, the driver IC can be pressed firmly against the flow path structure and joined reliably. Further, when the driver IC is pressed only to the peripheral area of the plurality of piezoelectric elements, the flow path structure may be warped toward the driver IC in the inner area (the area where the piezoelectric elements are arranged). In the present invention, the pressing force also acts on the inner region on one surface of the flow path structure, so that warpage is prevented.

  According to a fourth aspect of the present invention, in the liquid ejecting apparatus according to any one of the first to third aspects, the plurality of pressure chambers are arranged in a predetermined direction along the one surface of the flow path structure. The IC has a rectangular planar shape, and is disposed so as to face the one surface of the flow channel structure in a state where the long sides thereof are along the predetermined direction, The plurality of driving terminals are arranged in a region along a long side of the driver IC in a peripheral region of the plurality of piezoelectric elements, and the plurality of piezoelectric terminals on the one surface of the flow path structure are provided. The connection terminal other than the drive terminal is arranged in a region along a short side of the driver IC in a 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 a long side thereof, so that a length to be sealed is obtained. It is possible to reliably seal the long side having a large length. On the other hand, since the shorter side of the driver IC can be sealed with a smaller number of bumps than the longer side, connection terminals other than the driving terminals are arranged on the shorter side.

  In a liquid ejecting apparatus according to a fifth aspect, in any one of the first to fourth aspects, the plurality of bumps further include 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 disposed, and the sealing material is filled between the first bump and the second bump. It is characterized by having.

  The first bumps electrically connect the driver IC and the connection terminals on the flow path structure side to contribute to driving of the piezoelectric element. Therefore, the number and the interval of the first bumps are determined by the size of the piezoelectric element. Due to restrictions such as pods and the like, it may not be possible to set them freely. However, if the distance between the first bumps is large, the sealing material is difficult to be held between the adjacent first bumps, and sealing is difficult. In this regard, in the present invention, a so-called dummy second bump, which is bonded 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 adjacent first bumps is large, the distance between the bumps can be reduced by disposing the second bump between them, so that the gap between the bumps can be securely filled with the sealing material. Can be sealed.

A piezoelectric actuator according to a sixth aspect includes: a plurality of piezoelectric elements disposed on one surface of a substrate; and a driver IC for driving the plurality of piezoelectric elements.
On the one surface of the substrate, 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, and the driver IC is A plurality of bumps disposed to face the one surface of the substrate so as to cover a plurality of piezoelectric elements, and one of the driver IC and the flow path structure is provided with a plurality of bumps protruding to the other side thereof; The driver IC is connected to the plurality of connection terminals disposed in the peripheral region of the plurality of piezoelectric elements by a plurality of first bumps included in the plurality of bumps, whereby the plurality of piezoelectric elements are connected to the driver. The semiconductor device is characterized by being surrounded by an IC and the plurality of first bumps, and filled with an insulating sealing material 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. Thus, the piezoelectric element can be shielded from the atmosphere to 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, a plurality of piezoelectric elements can be covered using the driver IC and the bumps for connecting the driver IC to the plurality of connection terminals on the flow path structure side. Thus, the piezoelectric element can be shielded from the atmosphere to prevent moisture without increasing the number of components.

FIG. 2 is a schematic plan view of the inkjet printer according to the embodiment. FIG. 3 is a plan view of the inkjet head. FIG. 3 is a plan view of an inkjet head (in a state where a driver IC is not attached). FIG. 4 is a sectional view taken along line IV-IV of FIG. 2. FIG. 5 is a sectional view taken along line VV of FIG. 2. It is a top view of the ink jet head concerning a modification. FIG. 7 is a sectional view taken along line VII-VII of FIG. 6. FIG. 11 is a plan view of an inkjet head according to another modification. FIG. 11 is a plan view of an inkjet head according to another modification. It is XX sectional drawing of FIG. FIG. 11 is a plan view of an inkjet head according to another modification. FIG. 10 is a plan view of an ink jet head (in a state where 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 ink jet printer of the present embodiment. First, a schematic configuration of the inkjet printer 1 will be described with reference to FIG. In the description below, the front side of the sheet of FIG. 1 is defined as an upper side, and the other side of the sheet of the paper is defined as a lower side, and the description will be given using directional terms “up” and “down” as appropriate. 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.

  On the upper surface of the platen 2, a recording paper 100 as a recording medium is placed. Further, above the platen 2, two guide rails 10 and 11 extending in the left-right direction (scanning direction) in FIG. 1 are provided. The carriage 3 is configured to be reciprocally movable in the scanning direction along two guide rails 10 and 11 in a region facing the platen 2. An endless belt 14 wound around two pulleys 12 and 13 is connected to the carriage 3. When the carriage driving motor 15 drives the endless belt 14, the carriage 3 is moved to an endless belt. 14 moves in the scanning direction as the vehicle travels.

  The inkjet head 4 (liquid ejecting device) is attached to the carriage 3 and moves in the scanning direction together with the carriage 3. The ink jet head 4 is connected to an ink cartridge (not shown) mounted on the printer 1 by a tube. 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 a 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 from an inkjet head 4 that reciprocates in a scanning direction (the left-right direction in FIG. 1) with a carriage 3 on a recording sheet 100 placed on a platen 2. 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. With the above operations, images, characters, and the like are recorded on the recording paper 100.

  Next, the inkjet head 4 will be described. FIG. 2 is a plan view of the ink jet head. 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 of FIG. 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 channel unit 20 has a structure in which five plates 30 to 34 each having a large number of flow channel forming holes are stacked. When the five plates 30 to 34 are stacked, a large number of flow passage forming holes communicate with each other, so that the flow passage unit 20 has an ink flow passage described below. Although the material of the five plates 30 to 34 is not particularly limited, for example, a metal plate such as stainless steel or nickel alloy steel may be used. Alternatively, a silicon single crystal substrate may be used.

  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 channel unit 20. Inside the channel unit 20, two manifolds 25 are formed, each extending in the transport direction. 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 is formed on the lowermost nozzle plate 34 and communicates with the plurality of nozzles 16 opening to the lower surface of the flow path unit 20, respectively. It has a plurality of pressure chambers 24. As shown in FIGS. 2 and 3, the plurality of nozzles 16 are arranged in two rows along the transport direction on the lower surface of the flow path unit 20 (the surface opposite to the paper surface in FIGS. 2 and 3). Note that the arrangement of the plurality of nozzles 16 is a so-called staggered arrangement in which the positions of the nozzles 16 are mutually shifted in the transport direction between the two left and right nozzle rows.

  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 by the diaphragm 30 from above. Further, the plurality of pressure chambers 24 are arranged in two rows in a staggered manner along the transport direction, corresponding to the plurality of nozzles 16, respectively. Each pressure chamber 24 communicates with a corresponding nozzle 16 at one longitudinal end thereof. The arrangement relationship between the pressure chambers 24 and the nozzles 16 is reversed between the two left and right pressure chamber rows. That is, as shown in FIGS. 2 to 4, in the left pressure chamber row, the nozzles 16 corresponding to the longitudinal right end of each pressure chamber 24 communicate with each other. On the other hand, in the right pressure chamber row, the nozzle 16 corresponding to the longitudinal left end of each pressure chamber 24 communicates. Thus, as shown in FIGS. 2 and 3, two nozzle rows corresponding to the two 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. Thereby, as shown in FIG. 4, a plurality of individual ink flow paths 27 branching from the manifold 25 and reaching the nozzles 16 through the pressure chambers 24 are formed in the flow path unit 20.

  Next, the piezoelectric actuator 21 will be described. The piezoelectric actuator 21 is disposed on the upper surface of the vibration plate 30 of the channel unit 20. As shown in FIGS. 2 to 4, the piezoelectric actuator 21 has a piezoelectric body 40, a plurality of drive electrodes 42, and a common electrode 43.

  As shown in FIG. 4, on the upper surface of the diaphragm 30, an insulating film 44 made of an insulating material such as a synthetic resin material is formed on almost the entire surface. On the upper surface of the vibration plate 30 covered with the insulating film 44, two piezoelectric members 40 formed in a rectangular shape are arranged. The two piezoelectric bodies 40 are arranged so as to cover the two pressure chamber rows, respectively, such that their longitudinal directions are parallel to the arrangement direction (transport direction) of the pressure chambers 24. 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 formed directly on the upper surface of the vibration plate 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 be formed by firing an unfired thin green sheet and then attaching the green sheet to the vibration plate 30.

  The plurality of drive electrodes 42 are formed on the lower surface of the piezoelectric body 40 in regions facing the plurality of pressure chambers 24, respectively. Each drive electrode 42 has a substantially elliptical planar shape slightly smaller than the pressure chamber 24, and is arranged 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 pulled out from the corresponding drive electrode 42 on the insulating film 44 in the longitudinal direction toward the opposite side (outside) of the nozzle 16 to a region not opposed to the pressure chamber 24, as shown in FIG. 3, exposed from the piezoelectric body 40 as shown in FIG. The plurality of drive terminals 45 are arranged along the transport 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 driving terminals 45, and a predetermined driving voltage is applied from the driver IC 46 to each of the plurality of driving electrodes 42.

  The common electrode 43 is formed so as to straddle the two piezoelectric bodies 40 and cover the entire upper surface of the piezoelectric bodies 40. In FIG. 3, the common electrode 43 covering the two piezoelectric bodies 40 is hatched. Specifically, the common electrode 43 includes two electrode portions 43a formed over the entire upper surface of the two piezoelectric members 40, and one common direction (upstream side in the transport direction) of the pressure chambers 24 from the two electrode portions 43a. The first connection portion 43b is drawn out and formed on the upper surface of the vibration plate 30, and the second connection portion 43c is formed in a region between the two piezoelectric members 40 on the upper surface of the vibration plate 30.

  The first connection portion 43b extends in the scanning direction along short sides of the two rectangular piezoelectric members 40. The second connection portion 43c extends in the transport direction along the long sides of the two rectangular piezoelectric members 40. The first connection portion 43b and the second connection portion 43c are electrically insulated from the diaphragm 30 by the insulating film 44. Further, since the first connection portion 43b and the second connection portion 43c are both formed on the upper surface of the vibration plate 30, they are located at positions 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 concave shape at the second connection portion 43c. Note that the first connection portion 43b is located on the upper surface of the diaphragm 30 in the transport direction upstream of the region where the plurality of pressure chambers 24 are formed. The second connection portion 43c faces the partition wall portion 20a of the flow path unit 20, which separates the two rows of the pressure chambers 24. That is, both the first connection portion 43b and the second connection 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 on the upstream side in the transport direction with respect to the two piezoelectric members 40 and the second connecting portion 43c located between the two piezoelectric members 40 are both connected to a driver IC 46 to be described later. Conducted with the ground wiring. Thus, the common electrode 43 is always kept at the ground potential.

  As shown in FIG. 4, a portion (hereinafter, also referred to as “piezoelectric element 41”) of the piezoelectric body 40 sandwiched between one drive electrode 42 and the electrode portion 43a of the common electrode 43 is, as 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, a plurality of piezoelectric elements 41 corresponding to one row of pressure chambers are integrated by arranging one piezoelectric body 40 over a plurality of pressure chambers 24 belonging to one row of pressure chambers. It is the configuration that was done. Each of the plurality of piezoelectric elements 41 is polarized in the thickness direction.

  When a 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 of the ground potential, and the portion of the piezoelectric body 40 between these two electrodes 42, 43 An electric field acts on the (piezoelectric element 41) in the thickness direction. Since the direction of the 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 plane direction. Due to the contraction of the piezoelectric element 41, the vibration plate 30 covering the pressure chamber 24 is bent so as to protrude toward the pressure chamber 24, and the volume of the pressure chamber 24 is reduced. At that time, a pressure (ejection energy) is applied to the ink in the pressure chamber 24, and an ink droplet is ejected 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 disposed so as to face the upper surface of the vibration plate 30 of the flow path unit 20 with its long side along the direction in which the pressure chambers 24 are arranged, and covers the two piezoelectric members 40 from above. It is joined to diaphragm 30.

  As described above, a plurality of drive terminals 45 respectively drawn out from the 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, a first connection portion 43b of the common electrode 43 is disposed on 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 (a power input terminal 47a, a ground input terminal 47b, and a 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) for controlling the operation of the inkjet head 4.

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

  On the other hand, on the lower surface (connection surface) of the driver IC 46 facing the diaphragm 30, a plurality of bumps 51 made of a conductive material, which are connected to the plurality of connection terminals 50 described above, are provided below (in FIG. (On 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 on two edges of the rectangular driver IC 46 along two long sides 46a and 46b, respectively. ing. A plurality of first common electrode bumps 51b connected to the first connection portion 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 connected to the plurality of input terminals 47 are provided at an edge 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 portion 43c of the common electrode 43 are provided at the center of the driver IC 46.

  The driver IC 46 is disposed on the upper surface of the diaphragm 30 with its long sides 46a and 46b being parallel to the transport direction, and the plurality of bumps 51 described above are formed on the upper surface of the diaphragm 30 by a plurality of connections. Each of them is connected to a terminal 50. When the driver IC 46 is connected to the control board via a plurality of input terminals 47 (power input terminal 47a, ground input terminal 47b, signal input terminal 47c), power supply from the control board side, ground connection, and Input of a control signal and the like are performed. The driver IC 46 is connected to the plurality of drive electrodes 42 via the plurality of drive terminals 45 and also to the common electrode 43. Thereby, the driver IC 46 individually applies a drive voltage 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 on the driver IC 46, the bumps 51a, 51b, and 51c provided along the entire periphery of the driver IC 46 (the present invention). (First bump) surrounds the two piezoelectric bodies 40 (the plurality of piezoelectric elements 41). 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 a synthetic resin is filled between the plurality of bumps 51 connecting the driver IC 46 and the plurality of connection terminals 50. Thereby, the space between the adjacent bumps 51 is insulated, and the gap between the bumps 51 is 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 are shielded from the atmosphere. Is done.

  The electrical 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 an anisotropic conductive film (ACF) or an anisotropic conductive paste (ACP), in which conductive particles are dispersed in a thermosetting resin, are provided on the upper surface of the diaphragm 30. Are arranged so as to cover the connection terminals 50. Next, the driver IC 46 is pressed against the diaphragm 30 while heating the flow path unit 20. At this time, between the bumps 51 on the driver IC 46 side and the connection terminals 50, a large pressure acts locally on the anisotropic conductive material to extrude the thermosetting resin to the side, and the remaining conductive particles cause the bumps 51 to move. And the connection terminal 50 conducts. 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. It should be noted that almost no pressure acts on a 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-described sealing material 52 that insulates between the bumps 51 and seals the gap. I 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 the 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 provided by using the driver IC 46 for driving the piezoelectric actuator 21 and the bumps 51 for connecting the driver IC 46 to the plurality of connection terminals 50 on the channel unit 20 side. 41 is covered from the atmosphere. Therefore, the plurality of piezoelectric elements 41 can be reliably prevented from moisture without increasing the number of parts by adding a dedicated member.

  Further, as shown in FIGS. 2 to 4, a plurality of connection terminals 50 (a plurality of drive terminals 45, a first connection portion 43 b of the common electrode 43, a second connection portion 43 c, and a plurality of 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 vibration plate 30 against which the plurality of bumps are pressed can withstand the pressing force. Therefore, the vibration plate 30 is unlikely to be bent when the driver IC 46 is joined, and the bending of the vibration plate 30 prevents the piezoelectric body 40 (piezoelectric element 41) from being damaged.

  Further, a second connection portion 43c of the common electrode 43 is formed in a region of the vibration plate 30 facing the partition wall portion 20a separating the two rows of pressure chambers 24, and a second common electrode bump 51d is formed on the second connection portion 43c. Are joined. In other words, since the driver IC 46 is pressed via the bumps 51d even in the region where the plurality of pressure chambers 24 are arranged, the driver IC 46 can be pressed firmly against the flow path unit 20 and securely joined. When the driver IC 46 is pressed only to the peripheral area of the piezoelectric body 40, on the contrary, the diaphragm 30 warps upward (to the driver IC 46 side) in the inner area (area where the piezoelectric body 40 is arranged). There is a possibility 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 warpage is prevented.

  In order to reliably shield the piezoelectric body 40 from the atmosphere, it is necessary to completely seal the gap between the bumps 51a, 51b, 51c (first bump) surrounding the piezoelectric body 40 with the sealing material 52. 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, in the area around the two piezoelectric bodies 40, areas 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 drive terminals 45 are arranged. This makes it possible to reliably seal the long side having a large length to be sealed. On the other hand, the shorter side of the driver IC 46 can be sealed with a smaller number of bumps than the longer side. Therefore, the input terminals 47 having a smaller number than the drive terminals 45 are arranged in a region along one short side 46 d of the driver IC 46 in the peripheral region of the piezoelectric body 40. The number of the first common electrode bumps 51b does not need to be so large for the first connection portion 43b arranged on the other short side 46c side of the driver IC 46 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 to provide the same number of the first common electrode bumps 51b as the plurality of input bumps 51c.

  Next, modified embodiments in which various changes are made to the above-described embodiment will be described. However, the components having the same configuration as the above embodiment are denoted 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 specific 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 51 b only at the first connection portion 43 b formed on the upstream side in the transport direction from the two piezoelectric bodies 40. Good. That is, the bump 51 may not be bonded to a region between the two piezoelectric members 40 facing the partition wall portion 20a separating 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 a plurality of input terminals 47, can be arranged.

  Further, in the above 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. However, 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 terminal 50 other than the driving terminal 45 may be arranged on the long side of the driver IC 46.

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

  For example, as shown in FIGS. 9 and 10, the driver IC 46 may be provided with a dummy bump 51e (second bump) 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 vibration plate 30 and is not electrically connected to the connection terminal 50 such as the drive terminal 45. Further, a sealing material 52 is filled between the driving bump 51a and the dummy bump 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 to contribute to driving of the piezoelectric element 41. Due to restrictions such as the size and the number of the elements 41, it may not be possible to set them freely. However, if the interval between the bumps 51 is large, the sealing material 52 is not easily held between the adjacent bumps 51, and sealing is difficult. In this regard, in the configurations of FIGS. 9 and 10, the dummy bumps 51 e can be arranged between the plurality of drive bumps 51 a and the interval between the bumps 51 can be narrowed. Sealing can be performed reliably.

Further, in FIG. 9, the driving bumps 51a and the dummy bumps 51e are arranged on a straight line. However, as shown in FIG. 11, the driving bumps 51a and the dummy bumps 51e are arranged so as to be displaced in the scanning direction. These bumps 51 may be arranged in a staggered manner. 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, compared to a configuration in which the driving bumps 51a and the dummy bumps 51e are arranged on a straight line (FIG. 9), the thickness of the sealing material 52 held between the bumps 51 can be increased. There is also an advantage that the stopping function is improved.

  In the above-described embodiment (FIGS. 2 to 4), a bump for conducting to the common electrode 43 (the second bump) is provided in a region of the diaphragm 30 facing the partition wall portion 20a separating the two pressure chamber rows. Although the common electrode bump 51d) has been joined, as described above, if only the purpose of preventing the warp of the diaphragm 30 is to be prevented, this bump need not be a bump for electrode conduction, and may be a dummy bump. It may be.

3] In the above-described embodiment, as shown in FIG. 3, one piezoelectric element 40 is disposed across 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 configuration. On the other hand, as shown in FIG. 12, the plurality of piezoelectric elements 41 may be separated from each other and arranged at the center of the plurality of pressure chambers 24, respectively.

4] As can be understood from FIGS. 2 and 3 of the embodiment, in order for the plurality of piezoelectric elements 41 to be covered by the driver IC 46, the size of the driver IC 46 is larger than the area where the plurality of piezoelectric elements 41 are arranged. Must have a flat area. Conversely, the maximum number of piezoelectric elements 41 (that is, the maximum number of nozzles 16) of one head is restricted by the size of the driver IC 46. However, this does not mean that the application of the present invention makes it difficult to realize an inkjet head having a large number of nozzles 16. That is, by combining a plurality of head units as shown in FIGS. 2 and 3, an ink jet head having more nozzles 16 can be easily realized.

5] In the above-described embodiment, the driver IC 46 is provided with the plurality of bumps 51 connecting the driver IC 46 and the plurality of connection terminals 50. However, the plurality of bumps 51 are connected to the plurality of connection The terminal 50 may be formed so as to protrude upward (toward the driver IC 46).

  The above-described embodiment and its modified embodiments are examples in which the present invention is applied to an ink-jet head which is a liquid ejecting apparatus. However, the piezoelectric actuator of the present invention is not applicable to those used for applying pressure to a liquid. Not limited. A plurality of piezoelectric elements are arranged on a substrate, and each of the plurality of piezoelectric elements is driven by a driver IC to deform the substrate, thereby causing displacement, vibration, and the like in each of a plurality of solid driving objects. It may be used for a purpose.

4 Inkjet head 16 Nozzle 20 Flow path unit 20a Partition 21 Piezoelectric actuator 24 Pressure chamber 30 Vibrating plate 40 Piezoelectric 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 (10)

A first substrate;
A plurality of piezoelectric elements arranged on one surface of the first substrate;
A second substrate for supplying a signal for driving the plurality of piezoelectric elements,
The plurality of piezoelectric elements are arranged in a first direction,
The plurality of piezoelectric element rows are arranged in a second direction intersecting with the first direction, and a plurality of connection terminals respectively connected to the plurality of piezoelectric elements are provided on the one surface of the first substrate. Arranged in a region between the plurality of piezoelectric element rows ,
The second substrate is disposed on the one surface side of the first substrate,
The plurality of bumps are connected to the plurality of connection terminals disposed in a region between the second substrate and the plurality of piezoelectric element rows ,
Insulating material is provided, et al is between the bumps of the plurality of bumps,
The liquid ejecting apparatus according to claim 1, wherein the second substrate overlaps the plurality of piezoelectric element rows in a thickness direction . The liquid ejecting apparatus according to claim 1, wherein the plurality of rows of the piezoelectric elements are two rows . A first substrate;
A plurality of piezoelectric elements arranged on one surface of the first substrate;
A second substrate for supplying a signal for driving the plurality of piezoelectric elements,
The plurality of piezoelectric elements are arranged in a first direction,
The plurality of piezoelectric element rows are arranged in a plurality in a second direction intersecting with the first direction,
On the one surface of the first substrate, a plurality of connection terminals respectively connected to the plurality of piezoelectric elements are arranged in a region between the plurality of piezoelectric element rows ,
The second substrate is disposed on the one surface side of the first substrate,
The plurality of bumps are connected to the plurality of connection terminals disposed in a region between the second substrate and the plurality of piezoelectric element rows ,

An insulating material is provided between each bump in the plurality of bumps,
The liquid ejecting apparatus according to claim 1, wherein the bumps between the piezoelectric element rows are connected to a common electrode of the piezoelectric element.   The liquid ejecting apparatus according to claim 3, wherein the bump connected to the common electrode is connected only between the piezoelectric element rows. A first substrate;
A plurality of piezoelectric elements arranged on one surface of the first substrate;
A second substrate for supplying a signal for driving the plurality of piezoelectric elements,
The plurality of piezoelectric elements are arranged in a first direction,
The plurality of piezoelectric element rows are arranged in a plurality in a second direction intersecting with the first direction,
On the one surface of the first substrate, a plurality of connection terminals respectively connected to the plurality of piezoelectric elements are arranged in a region outside the plurality of piezoelectric element rows ,
The second substrate is disposed on the one surface side of the first substrate,
The plurality of bumps connect the second substrate and the plurality of connection terminals arranged in the outer region,

An insulating material is provided between each bump in the plurality of bumps,
The bump is bonded between the piezoelectric element rows on the one surface of the first substrate,
The liquid ejecting apparatus according to claim 1, wherein a distance between the plurality of bumps between the piezoelectric element rows is larger than a distance between the plurality of bumps in the outer region connected to the connection terminal.   The distance between the plurality of bumps between the piezoelectric element rows is larger than the distance between the plurality of bumps connected to the driving terminals connected to the plurality of piezoelectric elements, respectively. A liquid ejecting apparatus according to claim 1. A first substrate;
A plurality of piezoelectric elements disposed on one surface of the first substrate so as to face the plurality of pressure chambers, respectively;
A second substrate for supplying a signal for driving the plurality of piezoelectric elements,
The plurality of piezoelectric elements are arranged in a first direction,
The plurality of piezoelectric element rows are arranged in a second direction intersecting with the first direction, and a plurality of connection terminals respectively connected to the plurality of piezoelectric elements are provided on the one surface of the first substrate. It is arranged in an area outside the plurality of piezoelectric element rows ,
The second substrate is disposed on the one surface side of the first substrate,
By the plurality of bumps, the second substrate and the plurality of connection terminals arranged in the outer region of the plurality of piezoelectric elements are connected,
An insulating material is provided between each bump in the plurality of bumps,
The liquid ejecting apparatus according to claim 1, wherein the bumps are arranged so as to be displaced in the second direction and arranged in a staggered manner.   8. The liquid ejecting apparatus according to claim 7, wherein the staggered bumps include a first bump connected to the connection terminal and a second bump not connected to the connection terminal.   9. The liquid ejecting apparatus according to claim 1, wherein the insulating material is provided at least on both sides of the bump in the second direction. 10. A first substrate;
A plurality of piezoelectric elements arranged on one surface of the first substrate;
A second substrate for supplying a signal for driving the plurality of piezoelectric elements,
The plurality of piezoelectric elements are arranged in a first direction,
The plurality of piezoelectric element rows are arranged in a plurality in a second direction intersecting with the first direction,
Wherein the first said one surface of a substrate, a plurality of connection terminals respectively connected to said plurality of piezoelectric elements are disposed in a region between the plurality of piezoelectric element arrays,
The second substrate is disposed on the one surface side of the first substrate,
The plurality of first bumps included in the plurality of bumps connect the second substrate and the plurality of connection terminals arranged in a region between the plurality of piezoelectric element rows ,

An insulating material is provided between the bumps of the plurality of bumps between the piezoelectric element rows ,
The piezoelectric actuator according to claim 2, wherein the second substrate overlaps the plurality of piezoelectric element rows in a thickness direction .

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