JP6481740B2 - Liquid ejection device - Google Patents

Description

  The present invention relates to a liquid ejection apparatus.

  2. Description of the Related Art Conventionally, liquid ejecting apparatuses having a piezoelectric actuator that imparts jetting energy to a liquid are known. For example, Patent Document 1 discloses an inkjet head having a flow path forming substrate in which a plurality of pressure chambers communicating with a plurality of nozzles are formed, and a piezoelectric actuator provided on the flow path forming substrate. Yes.

  The piezoelectric actuator has a plurality of piezoelectric elements disposed on the surface of an elastic film covering the plurality of pressure chambers of the flow path forming substrate so as to face the plurality of pressure chambers. Further, the flow path forming substrate is provided with a cover member (reservoir forming substrate) so as to cover the plurality of piezoelectric elements, and the plurality of piezoelectric elements are sealed by the cover member. Further, in order to make the thermal expansion coefficient of the cover member and the flow path forming substrate the same, the same silicon single crystal as that of the flow path forming substrate is used as the material of the cover member.

  A plurality of terminal portions connected to the plurality of piezoelectric elements and extending to the outside of the cover member are provided on the surface of the flow path forming substrate. A flexible substrate on which a drive circuit unit for driving a plurality of piezoelectric elements is mounted is disposed on the cover member. The drive circuit unit is electrically connected to the plurality of terminal units via a wiring pattern provided on the surface of the flexible substrate.

JP 2010-208345 A

  In the ink-jet head disclosed in Patent Document 1, the drive circuit unit is flip-chip mounted on a flexible substrate formed of an insulating resin material. That is, the drive circuit unit has a configuration in which a circuit is built in a semiconductor substrate fixed to a flexible substrate. Therefore, when the number of nozzles increases and the number of piezoelectric elements increases, the semiconductor material used for the drive circuit section increases. Since the semiconductor material is expensive, the material cost of the ink jet printer is increased.

  An object of the present invention is to provide a liquid ejection device that can reduce the amount of semiconductor material used.

  According to a first aspect of the present invention, there is provided a liquid discharge device including a flow channel structure in which a liquid flow channel including a nozzle and a pressure chamber communicating with the nozzle is formed, and one surface of the flow channel structure facing the pressure chamber. And a cover member disposed on the one surface of the flow path structure so as to cover the piezoelectric element, and a circuit element for controlling discharge is formed on the surface of the cover member. It is characterized by being included.

  In the present invention, the piezoelectric element is sealed by being covered with the cover member. This prevents external moisture (humidity) from entering the piezoelectric element and causing a short circuit or migration.

  In the present invention, circuit elements for discharge control are built in the surface of the cover member. Since the cover member also serves as a member that covers the piezoelectric element and a semiconductor substrate for forming circuit elements, the amount of semiconductor material used can be reduced compared to the case where the circuit substrate is mounted on a member other than the cover member. As a result, the material cost of the liquid ejection device can be reduced.

  In the liquid ejection device according to a second aspect, in the first aspect, a connection terminal connected to an electrode provided on the piezoelectric element is disposed outside the cover member on the one surface of the flow path structure. And a flexible wiring board that is disposed along the surface of the cover member and electrically connects the circuit element and the connection terminal.

  Since the circuit element formed on the surface of the cover member and the connection terminal arranged on the one surface of the flow path structure are not arranged on the same plane, the circuit element and the connection terminal have flexibility. Connecting with the flexible wiring board facilitates connection work.

  In the liquid ejection device according to a third aspect of the present invention, in the second aspect of the invention, the flow channel structure is connected to a plurality of nozzles and the plurality of nozzles, and the one surface of the flow channel structure. A plurality of the pressure chambers arranged along a predetermined direction parallel to the plurality of pressure chambers, and a plurality of the piezoelectric elements respectively corresponding to the plurality of pressure chambers are arranged along the predetermined direction. A plurality of individual terminals respectively connected to the plurality of individual electrodes provided along the predetermined direction, the cover member covering the plurality of piezoelectric elements in common, and the flexible wiring board And the cover member, the circuit element, and the plurality of individual terminals are filled with a sealing material, and the circuit element is parallel to the one surface of the flow path structure of the cover member. Formed on the top A plurality of output portions formed on the top surface of the cover member and arranged along the predetermined direction, and connected to the plurality of individual terminals via the flexible wiring board, And a plurality of amplifying portions formed on the side surface of the cover member that is continuous with the top surface and arranged along the predetermined direction, and respectively corresponding to the plurality of individual terminals.

  According to the present invention, the input part and the output part of the circuit element are formed on the top surface of the cover member. Therefore, compared with the case where the input part and the output part are formed on the side surface of the cover member, it is easier to connect the input part and the output part and the wiring part of the flexible wiring board.

  Moreover, since the circuit element is a laminated body including a conductive pattern disposed on the surface of the cover member, the circuit element slightly protrudes from the surface of the cover member. The plurality of amplifying units of the circuit element are arranged in a predetermined direction on a side surface continuous with the top surface of the cover member. Therefore, on the side surface of the cover member, concave portions formed between adjacent amplification portions and convex portions by the amplification portions are alternately formed in a predetermined direction. Therefore, when a sealing material is injected between the flexible wiring board and the top surface of the cover member, and the sealing material is filled between the flexible wiring board and the cover member, the circuit element, and the plurality of individual terminals. Since the sealing material easily flows between adjacent amplification parts (concave portions), the sealing material is more easily distributed to the individual terminal side than the amplification part.

  In the liquid ejection device according to a fourth aspect, in the third aspect, a plurality of grooves extending in the direction from the top surface of the cover member toward the plurality of individual terminals are formed on the surface of the amplification section. It is characterized by that.

  In the present invention, when the sealing material is filled, the sealing material is likely to flow along the groove portion of the amplifying unit, and therefore, the sealing material is more easily distributed on the individual terminal side than the amplifying unit.

  According to a fifth aspect of the present invention, in the third or fourth aspect of the invention, the side surface of the cover member is a surface inclined with respect to the top surface and a surface perpendicular to the top surface. And

  In the present invention, the side surface connected to the top surface of the cover member is inclined with respect to the top surface and a surface perpendicular to the top surface. Therefore, compared with the case where the side surface is perpendicular to the top surface, the encapsulating material can be smoothly moved from the top surface to the side surface, so that the encapsulating material is easily filled.

  According to a sixth aspect of the present invention, in the liquid ejection device according to any one of the third to fifth aspects, the input unit and the plurality of output units are arranged in the predetermined direction, and the flexible unit is interposed via a bump. Two pumps that are electrically connected to the wiring board and are adjacent to each other in the predetermined direction are separated in a direction orthogonal to the predetermined direction.

  In the present invention, two bumps adjacent to each other in the predetermined direction are separated in a direction orthogonal to the predetermined direction. Therefore, compared with the case where a plurality of bumps are arranged in a line in the predetermined direction, the gap between the bumps can be secured widely, so that the sealing material is easily filled.

  In the present invention, the circuit element for discharge control is built in the surface of the cover member that covers the piezoelectric element. This eliminates the need for a semiconductor substrate for forming circuit elements, thereby reducing the amount of semiconductor material used.

1 is a schematic plan view of a printer according to an embodiment. FIG. 2 is a block diagram schematically showing an electrical configuration of the printer of FIG. 1. It is a top view of an inkjet head. FIG. 4 is a sectional view taken along line IV-IV in FIG. 3. These are the top views of the inkjet head in the state where the flexible wiring board, the sealing material, and the cover are not arrange | positioned. It is a partial expansion perspective view of a cover. FIG. 4 is a partially enlarged view of FIG. 3. It is a partial expansion perspective view of the cover of other embodiments of the present invention. It is a partial expansion perspective view of the cover of other embodiments of the present invention.

  Embodiments of the present invention will be described below. FIG. 1 is a schematic plan view of the ink jet printer of the present embodiment. First, the schematic configuration of the ink jet printer 1 will be described with reference to FIG. In the following description, the front side in FIG. 1 is defined as the upper side, and the other side of the page is defined as the lower side. In the following, the front side of the sheet of FIG. 1 is defined as “upper” of the printer 1 and the other side of the sheet is defined as “lower” of the printer 1. 1 is defined as the “left / right direction” of the printer 1. Hereinafter, description will be made using the front and rear and left and right direction words 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, a control device 6, and the like.

  The platen 2 supports a recording paper 100 that is a recording medium. The carriage 3 is configured to reciprocate in the scanning direction along the two guide rails 10 and 11 in a region facing the platen 2. An endless belt 14 is connected to the carriage 3, and the endless belt 14 is driven by a carriage motor 15, whereby the carriage 3 moves in the scanning direction.

  The inkjet head 4 (liquid ejection device) 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 17 attached to the printer 1 by a tube (not shown). 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 in FIG. 1). The inkjet head 4 ejects the ink supplied from the ink cartridge 17 to the recording paper 100 supported by the platen 2 from the plurality of nozzles 16.

  The transport mechanism 5 includes two transport rollers 18 and 19 disposed so as to sandwich the platen 2 in the transport direction. The transport mechanism 5 transports the recording paper 100 supported by the platen 2 in the transport direction by two transport rollers 18 and 19.

  The ink jet printer 1 causes ink to be ejected from a recording paper 100 supported on the platen 2 from an ink jet head 4 that reciprocates in the scanning direction together with the carriage 3. At the same time, the recording paper 100 is transported in the transport direction by the two transport rollers 18 and 19. Through the above operation, images, characters, and the like are recorded on the recording paper 100.

  FIG. 2 is a block diagram schematically showing the electrical configuration of the ink jet printer 1. As shown in FIG. 2, the control device 6 includes a CPU (Central Processing Unit) 60, a ROM (Read Only Memory) 61, a RAM (Random Access Memory) 62, an ASIC (Application Specific) configured by various control circuits, and the like. Integrated Circuit) 63. The control device 6 controls the operations of the ink jet head 1, the carriage motor 15 (see FIG. 1, omitted in FIG. 2), the transport motors (not shown) that drive the transport rollers 18 and 19, and the like. Let them print. The ASIC 63 of the control device 6 generates a drive signal (waveform signal) for driving the inkjet head 4 based on print data input from an external device such as a PC (not shown) and transmits the drive signal to the inkjet head 4.

  Next, the inkjet head 4 will be described. FIG. 3 is a plan view of the inkjet head 4. However, in FIG. 3, a part of a flexible wiring board 51 and a sealing material 52 to be described later are omitted. 4 is a cross-sectional view taken along line IV-IV in FIG. FIG. 5 is a plan view of the inkjet head 4 in a state where the flexible wiring board 51, the sealing material 52, and the cover 50 are not disposed. However, in FIG. 5, the cover 50 is indicated by a two-dot chain line so that the positional relationship with the cover 50 can be easily understood.

  As shown in FIGS. 3, 4, and 5, the inkjet head 4 includes a flow path unit 20 (the flow path structure of the present invention), a piezoelectric actuator 21, a cover 50, a flexible wiring board 51, and a seal. Materials 52 and 53 are provided.

  As shown in FIG. 4, the flow path unit 20 has a structure in which five plates 30 to 34 each having a flow path forming hole are laminated. When these five plates 30 to 34 are stacked, the respective flow path forming holes communicate with each other, whereby the flow path unit 20 is formed with an ink flow path as described below. The five plates 30 to 34 are made of, for example, a semiconductor material such as a silicon single crystal or a silicon carbide single crystal.

  As shown in FIGS. 3 and 5, an ink supply hole 26 connected to the ink cartridge 17 (see FIG. 1) is formed on the upper surface of the flow path unit 20. As shown in FIGS. 4 and 5, two manifolds 25 each extending in the transport direction are formed inside the flow path unit 20. The two manifolds 25 are commonly connected to one ink supply hole 26, and the ink supplied from the ink cartridge 17 is supplied to each of the two manifolds 25.

  The flow path unit 20 includes a plurality of nozzles 16 formed on the lowermost nozzle plate 34 and opening on the lower surface of the flow path unit 20, and a plurality of pressure chambers 24 respectively communicating with the plurality of nozzles 16. As shown in FIG. 5, 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 on the opposite side of the paper surface in FIG. 5). The arrangement of the plurality of nozzles 16 is a so-called staggered arrangement in which the positions of the nozzles 16 are shifted from each other in the conveyance direction between the two right and left 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 from above by a vibration plate 30 that is the uppermost plate. 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 the corresponding nozzle 16 at one longitudinal end thereof. 4 and 5, the nozzle 16 communicates with the left end of the pressure chamber 24 in the left nozzle row, and the nozzle 16 communicates with the right end of the pressure chamber 24 in the right nozzle row. Yes. Thus, the two nozzle rows are arranged so as to overlap with the outer ends of the two pressure chamber rows, respectively.

  The two pressure chamber rows are arranged at positions overlapping with the two manifolds 25, 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 through the pressure chambers 24.

  Next, the piezoelectric actuator 21 will be described. The piezoelectric actuator 21 is disposed on the upper surface of the vibration plate 30 that is a plate located in the uppermost layer of the flow path unit 20. As shown in FIGS. 4 and 5, the piezoelectric actuator 21 includes a piezoelectric body 40, a plurality of individual electrodes 42, and two common electrodes 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 surface of the vibration plate 30. Two piezoelectric bodies 40 each having a rectangular planar shape are disposed on the upper surface of the diaphragm 30 covered with the insulating film 44. Each piezoelectric body 40 is made of a piezoelectric material mainly composed of ferroelectric lead zirconate titanate (PZT), 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 be formed by baking an unfired thin green sheet and then attaching it to the diaphragm 30. Further, as shown in FIG. 5, the two piezoelectric bodies 40 are arranged so that their longitudinal directions are parallel to the nozzle arrangement direction so as to cover the two pressure chamber rows, respectively.

  The plurality of individual electrodes 42 are formed in regions on the upper surface of the piezoelectric body 40 that respectively face the plurality of pressure chambers 24. As a result, the plurality of individual electrodes 42 are arranged in two rows along the nozzle arrangement direction, like the plurality of pressure chambers 24. Each individual electrode 42 has a substantially oval planar shape that is slightly smaller than the pressure chamber 24, and is disposed so as to face the central portion of the corresponding pressure chamber 24.

  On the upper surface of the diaphragm 30 covered with the insulating film 44, a plurality of individual lead portions 42a connected to the ends of the plurality of individual electrodes 42 located on the opposite side of the nozzle 16 in plan view are formed. Has been. The individual lead-out portions 42 a are drawn out from the end portions of the corresponding individual electrodes 42 in the longitudinal direction (scanning direction) of the pressure chamber 24. Specifically, the individual lead-out part 42a is drawn to the right from the column of the left individual electrodes 42, and is drawn to the left from the column of the right individual electrodes 42. As a result, the plurality of individual lead portions 42 a are arranged along the transport direction inside the two piezoelectric bodies 40.

  The distal end portion of each individual lead portion 42a constitutes an individual terminal 42b connected to a wiring portion (not shown) of the flexible wiring board 51 described later. The individual electrode 42 is connected to the ASIC 63 of the control device 6 via the individual lead-out part 42 a (individual terminal 42 b), the wiring part of the flexible wiring board 51, and the head driving path circuit part 55 described later of the cover 50. . The ASIC 63 of the control device 6 generates a plurality of drive signals (waveform signals) respectively corresponding to the plurality of piezoelectric bodies 40. The drive signal sent from the ASIC 63 to the head drive circuit unit 55 is amplified to a predetermined drive potential by the head drive circuit unit 55 and applied to each individual electrode 42.

  Two common electrodes 43 respectively corresponding to two rows of pressure chambers are formed on the upper surface of the diaphragm 30 covered with the insulating film 44. The common electrode 43 extends in the transport direction across the plurality of pressure chambers 24 constituting one row of pressure chambers, and is in contact with substantially the entire lower surface of the corresponding piezoelectric body 40. Furthermore, as shown in FIG. 5, the common electrode 43 is drawn out from the region overlapping the lower surface of the piezoelectric body 40, that is, in the direction opposite to the drawing direction of the individual drawing portion 42 a from the individual electrode 42. This extracted portion (hereinafter referred to as extraction electrode portion 43a) is connected to a power supply wiring (not shown), and the potential of the common electrode 43 is always maintained at the ground potential.

  As shown in FIG. 4, a portion of the piezoelectric body 40 facing one pressure chamber 24 and sandwiched between one individual electrode 42 and the common electrode 43 (hereinafter also referred to as “piezoelectric element 41”) will be described later. As will be described, when the drive signal is supplied to the individual electrode 42, it is deformed and becomes a portion that applies ejection energy to the ink in one pressure chamber 24. Each of the plurality of piezoelectric elements 41 is polarized in the thickness direction. In the present embodiment, one piezoelectric body 40 is disposed across the plurality of pressure chambers 24 belonging to one row of pressure chambers, whereby a plurality of piezoelectric elements 41 corresponding to one row of pressure chambers are integrated. It has been configured. Each of the plurality of piezoelectric elements 41 is polarized in the thickness direction.

  When a driving voltage is applied to the individual electrode 42, a potential difference is generated between the individual electrode 42 and the common electrode 43 having the ground potential, and the portion of the piezoelectric body 40 between the two electrodes 42 and 43 (piezoelectric element). 41) an electric field in the thickness direction acts. 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, pressure (ejection energy) is applied to the ink in the pressure chamber 24, and ink droplets are ejected from the nozzles 16.

  In the present embodiment, the individual electrodes 42 are arranged on the upper surface of the piezoelectric body 40 and the common electrode 43 is arranged on the lower surface, but the arrangement of the electrodes 42 and 43 may be reversed. That is, the common electrode 43 may be disposed on the upper surface of the piezoelectric body 40 and the individual electrode 42 may be disposed on the lower surface.

  Next, the cover 50 will be described. FIG. 6 is a partially enlarged cross-sectional perspective view of the cover 50. FIG. 7 is a partially enlarged view of FIG. As shown in FIGS. 3 and 4, two covers 50 are provided corresponding to the two piezoelectric bodies 40. The two covers 50 are formed symmetrically.

  As shown in FIG. 5, the two covers 50 are fixed to the flow path unit 20 so as to cover the two piezoelectric bodies 40. The cover 50 prevents the moisture (humidity) from entering the piezoelectric element 41 by blocking the piezoelectric body 40 from the outside air. A plurality of individual terminals 42 b and leading ends of the extraction electrode portions 43 a are exposed to the outside of the cover 50.

  The cover 50 includes a cover main body 54 (cover member of the present invention) formed of the same semiconductor material as the flow path unit 20 and a head drive circuit portion 55 (circuit elements of the present invention) formed on the surface of the cover main body 54. ). Since the cover main body 54 and the flow path unit 20 are formed of the same semiconductor material, even if the piezoelectric actuator 21 becomes high temperature and the flow path unit 20 and the cover main body 54 are heated, the flow path unit. 20 and the cover main body 54 have the same coefficient of thermal expansion, distortion is unlikely to occur, and a decrease in printing accuracy can be suppressed.

  As shown in FIG. 4, the top surface 54 a of the cover body 54 has a rectangular shape and is parallel to the upper surface of the flow path unit 20. An edge of the top surface 54a on the side close to the individual terminal 42b is connected to the top surface 54a and an inclined surface 54b that is inclined with respect to a surface perpendicular to the top surface 54a. A vertical surface 54c perpendicular to the top surface 54a is connected to the lower end of the inclined surface 54b. In the present embodiment, the inclined surface 54b is inclined about 45 degrees with respect to the top surface 54a, but the inclination angle is not limited to this. The inclination angle should just be larger than 0 degree | times and smaller than 90 degree | times with respect to the top | upper surface 54a.

  The head drive circuit unit 55 includes a plurality of individual circuit units 56 arranged in the transport direction. The plurality of individual circuit units 56 are respectively disposed immediately above the plurality of individual drawing units 42a arranged in the transport direction. The head drive circuit unit 55 has a configuration in which conductive patterns and insulating patterns are stacked in the thickness direction, and slightly protrudes from the surface of the cover main body 54.

  As shown in FIGS. 6 and 7, each individual circuit unit 56 includes an input unit 56a and an output unit 56b formed on the top surface 54a, and an amplification unit 56c formed on the inclined surface 54b. .

  The input unit 56a and the output unit 56b are arranged side by side in the transport direction, and each extend in the scanning direction. With this configuration, a plurality of input portions 56a and a plurality of output portions 56b are alternately arranged along the transport direction one by one on the top surface 54a of the cover main body 54. In this embodiment, the input unit 56a and the output unit 56b have the same length (scanning direction length). For example, the input unit 56a is longer than the output unit 56b, or the input unit 56a is the output unit 56b. Or shorter.

  The amplifying unit 56c is formed in a substantially rectangular shape having one side along the boundary between the inclined surface 54b and the top surface 54a, and is connected to one end of each of the input unit 56a and the output unit 56b. On the inclined surface 54b of the cover main body 54, a plurality of amplifiers 56c are arranged in the transport direction. The area of the amplifying unit 56c is larger than the areas of the input unit 56a and the output unit 56b.

  The amplifying unit 56c is arranged in the transport direction, and a plurality of conductive patterns 57a each extending in the scanning direction and a plurality of conductive patterns 57b each arranged in the scanning direction and extending in the transport direction are alternately arranged via insulating patterns. It has the structure laminated | stacked on. In the present embodiment, the uppermost conductive pattern of the amplifying unit 56c is a conductive pattern 57a extending in the scanning direction. For this reason, a plurality of grooves 58 extending in the scanning direction are formed on the surface of the amplifying portion 56c, each of which is formed between the uppermost conductive patterns 57a.

  On the upper surface of each individual circuit portion 56, three bumps 59 made of a conductive material connected to a wiring portion (not shown) of the flexible wiring board 51 are provided so as to protrude. The input unit 56a is provided with two input bumps 59a arranged in the scanning direction. The output portion 56b is provided with one output bump 59b.

  The output bump 59b is disposed at a position away from the two input bumps 59a in the scanning direction. Specifically, the output bump 59b is disposed between the two input bumps 59a in the scanning direction. The positions of the two input bumps 59a and the output bumps 59b are not limited to the above. For example, the output bumps 59a and the output bumps 59b are arranged so that the distance from the amplification unit 56c in the scanning direction is the same as one of the two input bumps 59a. Bump 59b may be arranged. In order to prevent disturbance, it is preferable to place the output bump 59b as close to the amplification unit 56c as possible.

  Two flexible wiring boards 51 are provided corresponding to the two covers 50. The flexible wiring board 51 is disposed along the top surface 54 a, the inclined surface 54 b, the vertical surface 54 c of the cover body 54, and the head drive circuit unit 55. Further, the end portion of the flexible wiring board 51 is disposed along the upper surface of the flow path unit 20.

  The flexible wiring board 51 is made of an insulating resin, and has a flexible base film and a wiring portion made of a conductive material such as copper in close contact with the base film. The base film is transparent or translucent. This wiring section includes a power supply wiring section for supplying power and a signal wiring section for signal transmission. The wiring portion of the flexible wiring board 51 is connected to the plurality of input portions 56a and the plurality of output portions 56b of the head drive circuit portion 55 and the plurality of individual terminals 42b.

  The input unit 56 a of each individual circuit unit 56 is connected to the ASIC 63 via the one input bump 59 a of the two input bumps 59 a, the signal wiring unit of the flexible wiring board 51, and the like, and is transmitted from the ASIC 63. The received drive signal (waveform signal) is received. Further, power is supplied to the input portion 56 a of each individual circuit portion 56 via the other input bump 59 a and the power supply wiring portion of the flexible wiring board 51.

  The output part 56b of the individual circuit part 56 is connected to the individual terminal 42b corresponding to the individual circuit part 56 provided with the output bump 59b via the output bump 59b and the wiring part of the flexible wiring board 51. The drive signal (waveform signal) input to the input unit 56a is amplified to a predetermined drive potential by the amplifier 56c by the power supplied to the input unit 56a, and then sent from the output unit 56b to the individual terminal 42b.

  Between the flexible wiring board 51 and the top surface 54a, the inclined surface 54b, the vertical surface 54c, the head drive circuit unit 55, and the plurality of individual terminals 42b of the cover body 54, a seal made of an insulating material such as a synthetic resin is provided. The stop material 52 is filled. Thereby, the gaps between the adjacent bumps 59 are insulated, and the gap between the lower surface of the wall near the individual terminal 42 b in the cover 50 and the upper surface of the flow path unit 20 is sealed. Further, the sealing material 52 protects the surface of the head drive circuit unit 55.

  A space between the opposing surfaces of the two flexible wiring boards 51 is filled with a sealing material 53 formed of the same material as the sealing material 52. The flexible wiring board 51 is fixed to the cover 50 and the flow path unit 20 by the sealing material 53. Further, the sealing property of the cover 50 can be improved by the sealing material 53.

  When manufacturing the inkjet head 4, the piezoelectric actuator 21 is formed on the upper surface of the flow path unit 20, and then two covers 50 are arranged at predetermined positions so as to cover the two piezoelectric bodies 40. The cover 50 is joined to the flow path unit 20. Thereafter, the flexible wiring board 51 is arranged on each cover 50, and the wiring part of the flexible wiring board 51 is transferred to the head drive circuit part 55 by means of heating and pressurization of the flexible wiring board 51 or a conductive adhesive. The plurality of bumps 59 provided and the plurality of individual terminals 42b are connected.

  Since the input unit 56 a and the output unit 56 b of the individual circuit unit 56 are formed on the top surface 54 a of the cover body 54, the input unit 56 a and the output unit 56 b are formed on the inclined surface 54 b or the vertical surface 54 c of the cover body 54. Compared with the case where it is, it is easy to perform the operation | work which connects the input part 56a and the output part 56b, and the wiring part of the flexible wiring board 51. FIG.

  Further, the head drive circuit unit 55 formed on the surface of the cover main body 54 and the individual terminals 42b arranged on the upper surface of the flow path unit 20 are not arranged on the same plane. By connecting the individual terminals 42b with a flexible wiring board having flexibility, the connection work is facilitated. Furthermore, since the flexible wiring board 51 of the present embodiment is transparent or translucent, the connection work is easier to perform.

  Next, a paste-like sealing material 52 is injected between the top surface 54a of the cover main body 54 and the flexible wiring board 51, and between the flexible wiring board 51, the cover 50, and the plurality of individual terminals 42b. The sealing material 52 is filled. Thereafter, a sealing material 53 is filled between the opposing surfaces of the two flexible wiring boards 51.

  As described above, on the inclined surface 54b of the cover main body 54, the plurality of amplifying units 56c of the head drive circuit unit 55 are arranged along the transport direction. Therefore, on the inclined surface 54b of the cover main body 54, recesses formed between adjacent amplification units 56c and projections by the amplification units 56c are alternately formed in the transport direction (nozzle arrangement direction). become. Therefore, when the sealing material 52 is filled between the flexible wiring board 51 and the cover 50, the sealing material 52 easily flows between the adjacent amplification portions 56c (concave portions). It is easier to spread to the individual terminal 42b side.

  Further, a plurality of groove portions 58 each formed between the uppermost conductive patterns 57a are formed on the surface of the amplifying portion 56c. The groove 58 extends in a direction from the top surface 54a toward the plurality of individual terminals 42b. Therefore, when the sealing material 52 is filled between the flexible wiring board 51 and the cover 50, the sealing material 52 easily flows along the groove portion 58 of the amplifying portion 56c. It is easy to spread by the individual terminal 42b side.

  In addition, the inclined surface 54b connected to the top surface 54a of the cover body 54 is inclined with respect to the top surface 54a and the vertical surface 54c perpendicular to the top surface 54a. Therefore, compared with the case where the vertical surface 54c perpendicular to the top surface 54a is connected to the top surface 54a of the cover body 54, the sealing material 52 can be smoothly moved from the top surface 54a to the inclined surface 54b. It is easy to fill the sealing material 52 between the flexible wiring board 51 and the cover 50.

  Further, the bumps 59 (input bump 59a and output bump 59b) adjacent in the transport direction are arranged so as to be separated in the scanning direction. Therefore, compared with the case where the plurality of bumps 59 are arranged in a line in the transport direction, the gap between the bumps 59 can be secured widely, so that the sealing material 52 is easily filled between the flexible wiring board 51 and the cover 50. .

  In the present embodiment, the head drive circuit unit 55 is built in the cover main body 54. Therefore, since the cover main body 54 serves as a member that covers the piezoelectric element 41 and a semiconductor substrate for forming the head drive circuit portion 55, the semiconductor material is compared with the case where the circuit board is mounted on a member other than the cover main body 54. Can be reduced. As a result, the material cost of the inkjet printer 1 can be reduced.

  In addition, since the head drive circuit unit 55 that transmits the drive power applied to the individual electrode 42 is formed in the cover body 54 that covers the piezoelectric element 41, the drive power path can be shortened. Therefore, a wiring path with low impedance can be configured.

  Next, modified embodiments in which various modifications are made to the embodiment will be described. However, components having the same configuration as in the above embodiment are given the same reference numerals and description thereof is omitted as appropriate.

  In the embodiment, the input unit 56a and the output unit 56b are formed on the top surface 54a of the cover body 54, and the amplification unit 56c is formed on the inclined surface 54b of the cover body 54. The locations where the cover body 54 of the 56b and the amplifying portion 56c are formed are not limited to the above. For example, as shown in FIG. 8A, the input unit 256a of the head drive circuit unit 255 may be formed on the top surface 54a, and the output unit 256b and the amplification unit 256c may be formed on the inclined surface 54b. For example, as shown in FIG. 8B, the input unit 356a and the amplification unit 356c of the head drive circuit unit 355 may be formed on the top surface 54a, and the output unit 356b may be formed on the inclined surface 54b. Further, the input unit, the output unit, and the amplification unit of the head drive circuit unit may be formed only on the top surface 54a.

  In the embodiment, a plurality of drive signals (waveform signals) generated in the ASIC 63 of the control device 6 respectively corresponding to the plurality of individual electrodes 42 are amplified to a predetermined drive potential in the head drive circuit unit 55 to be individual terminals. By supplying to 42b, the deformation of the piezoelectric element 41 is controlled to control the ejection of ink, but the function of the circuit elements built into the cover body 54 is not limited to that of the above embodiment. However, any circuit may be used as long as it is a circuit related to ink ejection control.

  For example, a circuit element that performs both part of the processing performed by the ASCI 63 of the embodiment and the processing performed by the head drive circuit unit 55 may be built in the cover body 54. Specifically, the ASIC of the control device generates a control signal for driving the inkjet head 4 based on print data input from an external device such as a PC. The circuit element generates a plurality of drive signals (waveform signals) respectively corresponding to the plurality of individual electrodes based on the control signal transmitted from the ASIC, and amplifies the drive signals to a predetermined drive potential. The circuit element of this modification has a plurality of output units connected to the plurality of individual terminals 42b. In addition, the circuit element of this modification has a plurality of input parts to which a control signal from the control device 6 and power for amplifying the drive signal are supplied. The number of input units need not correspond to the number of individual electrodes 42. Further, the circuit element of this modified example may be formed only on the top surface 54a of the cover main body 54, and only a part of the circuit element (for example, the amplification unit) is formed on the top surface 54a of the cover main body 54. Other portions may be formed on the inclined surface 54 b of the cover main body 54.

  Further, as another example of the circuit element formed in the cover main body 54, for example, a temperature sensor IC for detecting the temperature of the inkjet head 4 may be used. The temperature sensor IC is connected to the control device 6. The lower the environmental temperature, the higher the viscosity of the ink. Therefore, the printing accuracy can be improved by changing the ink ejection control based on the detected temperature. Furthermore, in this modified example, since the temperature near the flow path unit 20 can be detected, the printing accuracy can be further improved. As an example of ink ejection control based on the temperature detected by the temperature sensor IC, for example, the magnitude of the drive voltage applied to the individual electrode 42 may be changed according to the temperature detected by the temperature sensor IC. .

  In the embodiment, the edge of the cover main body 54 on the side close to the individual terminal 42b of the top surface 54a is continuous with the top surface 54a and the inclined surface 54b inclined to the surface perpendicular to the top surface 54a. An edge on the individual terminal 42b side of the top surface 54a of 54 may be continuous with a surface perpendicular to the top surface 54a. That is, the amplification unit 56c may be formed on a surface perpendicular to the top surface 54a.

  In the embodiment, the cover 50 covers the plurality of piezoelectric elements 41 arranged in a line in common, but may include a plurality of covers that individually cover the plurality of piezoelectric elements 41. In this case, the individual circuit part 56 is formed in each cover.

  In the embodiment, the plurality of output portions 56b and the plurality of individual terminals 42b of the head drive circuit portion 55 are electrically connected via the flexible wiring board 51. For example, as shown in FIG. A plurality of wiring patterns 451 may be formed in 54, and the plurality of output patterns 56 b of the head drive circuit unit 255 and the plurality of individual terminals 42 b may be connected by the plurality of wiring patterns 451. The wiring pattern 451 extends to the lower end of the side surface of the cover main body 54 or to the lower surface of the cover main body 54 (that is, the joint surface with the flow path unit 20), and the tip end portion of the wiring pattern 451 is connected to the individual terminal. The In this modification, the flexible wiring board 51 and the sealing materials 52 and 53 may not be provided. However, it is preferable to provide a member that protects the surface of the head drive circuit portion 55. The wiring pattern 451 may be configured by the output unit 255b of the head drive circuit unit 255.

  In the modified example of FIG. 9, since the wiring pattern 451 and the individual terminal 42b are connected at the lower end of the side surface of the cover main body 54 or the lower surface of the cover main body 54, it is difficult to see the connection location. Further, since the cover main body 54 is a rigid body, the shape cannot be changed flexibly, and positioning of the cover main body 54 is difficult. On the other hand, in the above embodiment, the head drive circuit unit 55 and the plurality of individual terminals 42b are connected by the flexible wiring board 51 that is flexible and arranged along the cover main body 54, so that the connection work is easy to perform. Therefore, from the viewpoint of connection workability, it is preferable that the head drive circuit unit 55 and the plurality of individual terminals 42 b are connected by the flexible wiring board 51.

  Further, the plurality of input portions 56 a of the head drive circuit portion 55 may also be electrically connected to a wiring pattern formed on the cover main body 54.

  In the embodiment, the sealing material 52 is filled between the flexible wiring board 51, the cover main body 54, the head drive circuit unit 55, and the plurality of individual terminals 42 b, but the flexible wiring board 51 and the cover 50 The sealing material may be filled only between the surface and the region where the head drive circuit unit 55 is formed in the scanning direction.

  In the above-described embodiment and its modifications, the present invention is applied to an ink discharge apparatus of an ink jet printer that discharges ink onto a recording sheet and prints an image or the like. The present invention can also be applied to a liquid ejection device used in various applications. For example, the present invention can also be applied to a liquid ejection device that ejects a conductive liquid onto a substrate to form a conductive pattern on the substrate surface.

DESCRIPTION OF SYMBOLS 1 Inkjet printer 4 Inkjet head 16 Nozzle 20 Flow path unit 21 Piezoelectric actuator 27 Individual ink flow path 41 Piezoelectric element 42 Individual electrode 42b Individual terminal 43 Common electrode 50 Cover 51 Flexible wiring boards 52 and 53 Sealing material 54 Cover body 54a Top surface 54b Inclined surface 55 Head drive circuit unit 56 Individual circuit unit 56a Input unit 56b Output unit 56c Amplifying unit 58 Groove unit 59 Bump

Claims (18)

A channel structure in which a liquid channel including a nozzle and a pressure chamber communicating with the nozzle is formed;
A piezoelectric element disposed on one surface of the flow path structure opposite to the pressure chamber;
A cover member disposed on the one surface of the flow path structure so as to cover the piezoelectric element;
A circuit element formed on the surface of the cover member for controlling discharge;
A flexible wiring board electrically connected to the circuit element,
A sealing material is disposed on a surface of the circuit element;
The circuit element is:
An input section;
A plurality of output portions formed in an array;
A plurality of amplifiers that are formed in an array and amplify signals input to the input unit;
The cover member is
A top surface on which the circuit element is formed;
A side surface connected to the top surface and connected to the flow path structure;
Have
The liquid ejection device, wherein the sealing material is disposed over the top surface and the side surface.   The liquid ejecting apparatus according to claim 1, wherein the sealing material seals the circuit element. The sealing material is
The liquid ejection device according to claim 1, wherein the liquid ejection device is provided between the flexible wiring board and the circuit element.   The liquid ejection apparatus according to claim 3, wherein the sealing material is disposed between the adjacent output units. The flexible wiring board is
The liquid ejection apparatus according to claim 1, wherein the liquid ejection apparatus is connected to the input unit.   The liquid ejecting apparatus according to claim 5, wherein the input unit is electrically connected to the flexible wiring board via a bump.   The liquid ejecting apparatus according to claim 6, wherein a sealing material is provided between two adjacent bumps of the plurality of input units. The flexible wiring board is
The liquid ejecting apparatus according to claim 1, wherein the liquid covering device covers a surface of the cover member.   The liquid ejecting apparatus according to claim 8, wherein the sealing material covers a surface of the flexible wiring board.   The liquid ejecting apparatus according to claim 9, wherein the sealing material is formed over surfaces of the flexible wiring substrate and the flow path structure. The flexible wiring board is
The liquid ejecting apparatus according to claim 1, wherein the circuit element is covered. In the one surface of the flow channel structure, comprising an individual lead portion extending from the piezoelectric element to the outside of the cover member,
The liquid ejecting apparatus according to claim 1, wherein the sealing material is provided around the individual drawing portion outside the cover member. The flexible wiring board is electrically connected to the output unit and the individual lead-out unit,
The liquid ejecting apparatus according to claim 12, wherein the sealing material is formed on a surface of the flexible wiring board that overlaps the individual drawing portion. An individual terminal is provided at the tip of the individual drawer,
The circuit element is:
The input part is formed on the top surface of the cover member,
The plurality of output units respectively correspond to the plurality of individual terminals,
Said plurality of amplifier portions are formed on the side surface of the cover member, a liquid ejecting apparatus according to claim 1 2, characterized in that respectively corresponding to the plurality of individual terminals.   The liquid ejecting apparatus according to claim 14, wherein a plurality of grooves extending in a direction from the top surface of the cover member toward the plurality of individual terminals are formed on the surface of the amplification unit.   The liquid ejecting apparatus according to claim 14, wherein the side surface of the cover member is a surface inclined with respect to the top surface and a surface perpendicular to the top surface. Wherein the plurality of output portions and the input section, together with being arranged in a predetermined direction, are electrically connected to the flexible wiring board via bumps,
17. The liquid ejection apparatus according to claim 14, wherein two pumps adjacent in the predetermined direction are separated from each other in a direction orthogonal to the predetermined direction. A channel structure in which a liquid channel including a nozzle and a pressure chamber communicating with the nozzle is formed;
A piezoelectric element disposed on one surface of the flow path structure opposite to the pressure chamber;
A cover member disposed on the one surface of the flow path structure so as to cover the piezoelectric element,
Circuit elements for discharge control are built in the surface of the cover member,
A flexible wiring board electrically connected to the circuit element;
Between the flexible wiring board, the cover member and the circuit element, a sealing material is filled,
The cover member is
A top surface on which the circuit element is formed;
A side surface connected to the top surface and connected to the flow path structure;
Have
The liquid ejection device, wherein the sealing material is disposed over the top surface and the side surface.

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