JP4581709B2 - Inkjet head - Google Patents

Description

  The present invention relates to an inkjet head that performs printing by discharging ink onto a recording medium.

  In an ink jet printer or the like, an ink jet head distributes ink supplied from an ink tank to a plurality of pressure chambers, and ejects ink from nozzles by selectively applying a pulsed pressure to each pressure chamber. As one means for selectively applying pressure to the pressure chamber, an actuator unit in which a plurality of piezoelectric sheets made of piezoelectric ceramic are laminated may be used.

  As an example of such an ink jet head, a continuous plate-shaped piezoelectric sheet is arranged facing a common electrode formed across a plurality of pressure chambers, and facing each pressure chamber, and a voltage is applied from the main electrode portion and the outside. One having a plurality of actuator units sandwiched between a plurality of individual electrodes made up of auxiliary electrode portions is known (see Patent Document 1). The portion of the piezoelectric sheet sandwiched between the individual electrode and the common electrode and polarized in the stacking direction is set to a potential different from that of the common electrode by supplying a driving voltage from a flexible printed circuit (FPC). And it expands and contracts in the stacking direction due to the so-called piezoelectric longitudinal effect. As a result, the volume in the pressure chamber fluctuates, and ink can be ejected from the nozzles communicating with the pressure chamber toward the recording medium. Further, in one actuator unit, all the individual electrodes are arranged along one direction while the auxiliary electrode portions are all formed on the same side with respect to the main electrode portion. On the other hand, in the FPC connected to the auxiliary electrode portion, a plurality of connection pads (terminals) are formed corresponding to the arrangement state of each auxiliary electrode portion.

JP 2003-311953 A

  However, in the inkjet head described in Patent Document 1 described above, since the auxiliary electrode portions of the plurality of individual electrodes of the actuator unit are all arranged in the same direction, there is a demand for higher resolution of images and high-speed printing. As the pressure chambers are arranged at a high density to cope with this, the distance between the auxiliary electrode parts becomes smaller, and the distance between the connection pads of the FPC corresponding to each auxiliary electrode part becomes smaller. Along with this, the width and interval of wiring drawn from each connection pad of the FPC are becoming narrower as the manufacturing limit is exceeded. For this reason, there is a problem in that the required resolution is increased and the pressure chamber is increased in density, and the size of the inkjet head is increased.

  Accordingly, an object of the present invention is to provide an ink jet head capable of widening the wiring interval formed on a flat flexible cable such as an FPC without increasing the interval between individual electrodes.

Means for Solving the Problems and Effects of the Invention

An ink jet head according to the present invention includes a flow path unit in which a plurality of pressure chambers each communicating with a nozzle are arranged along a plane, and an ink flow path extending from an ink supply port to the nozzle through the pressure chamber And a plurality of individual electrodes each having a main electrode region formed corresponding to the pressure chamber and an auxiliary electrode region connected to the main electrode region, and fixed to the plane of the flow path unit and the pressure An actuator unit that applies ejection energy to the ink in the chamber, and a plurality of terminals that are electrically connected to the auxiliary electrode region, respectively, and a plurality of wirings that are respectively connected to the plurality of terminals extend in one direction. And a flat flexible cable drawn from the terminal. In the actuator unit, a plurality of individual electrode rows in which a plurality of individual electrodes are arranged along a direction intersecting the one direction are arranged in parallel to each other, and among the plurality of individual electrode rows, In the individual electrode row farthest away in the direction in which the wiring is drawn from at least the tip of the flat flexible cable, the auxiliary electrode region is closer to the tip of the flat flexible cable than the main electrode region The auxiliary electrode regions are alternately arranged with the individual electrodes on the proximal end side of the flat flexible cable with respect to the main electrode region.

  According to this, the width and interval of the wiring formed in the flat flexible cable can be made relatively large without increasing the interval between the individual electrodes. In other words, the individual electrode row closest to the base end of the flat flexible cable includes an individual electrode whose auxiliary electrode region is on the distal end side of the flat flexible cable and an individual electrode whose auxiliary electrode region is on the proximal end side of the flat flexible cable. Since the electrodes are mixed, another auxiliary electrode region may not exist between the two auxiliary electrode regions located on the proximal end side of the flat flexible cable with respect to the main electrode region. A plurality of wirings with relatively large wiring widths and wiring intervals can be formed between the two auxiliary electrode regions. Therefore, it becomes easy to produce a flat flexible cable. In addition, it is possible to cope with higher resolution of images and higher density of pressure chambers, and it is possible to prevent enlargement of the ink jet head associated therewith.

Moreover , the space | interval of the terminal formed corresponding to the individual electrode nearest to the base end of a flat type flexible cable can be made wide equally over the whole region. Therefore, it becomes easier to produce a flat flexible cable. In addition, it becomes easy to cope with higher image density and higher pressure chamber density.

  In the present invention, in all the individual electrode rows, the auxiliary electrode region is closer to the distal end side of the flat flexible cable than the main electrode region, and the auxiliary electrode region is more than the main electrode region. It is preferable that the individual electrodes on the base end side of the flat flexible cable are mixed. Thereby, the width and interval of the wiring connected to each of the terminals formed corresponding to all the individual electrode rows can be increased. Therefore, it becomes easier to produce a flat flexible cable. In addition, it becomes easier to cope with higher image density and higher pressure chamber density.

  In the present invention, in all the individual electrode rows, the auxiliary electrode region is closer to the distal end side of the flat flexible cable than the main electrode region, and the auxiliary electrode region is more than the main electrode region. It is preferable that the individual electrodes on the base end side of the flat flexible cable are alternately arranged. As a result, the distance between the terminals formed corresponding to all the individual electrode rows can be evenly widened over a wide range. Therefore, it becomes easier to produce a flat flexible cable. In addition, it becomes easier to cope with higher image density and higher pressure chambers.

  Further, at this time, the actuator unit has a plurality of individual electrode rows in which the individual electrodes belonging to every other individual electrode column are arranged in parallel along the one direction so as to be parallel to each other. The plurality of individual electrodes belonging to two adjacent individual electrode rows may belong to different individual electrode columns. This makes it possible to arrange a plurality of individual electrodes in a staggered pattern in the column direction with high density.

  Further, at this time, the individual electrode row includes the individual electrode in which the auxiliary electrode region is on the distal end side of the flat flexible cable with respect to the main electrode region, and the auxiliary electrode region is more than the main electrode region. There may be a region where the individual electrodes on the base end side of the flat flexible cable are alternately arranged. As a result, an area having a wide terminal interval can be reliably formed within the terminal distribution area, so that a margin is created in the width and interval of the wiring in the flat flexible cable. Further, the individual electrode row includes a first individual region in which the auxiliary electrode region has a region in which a plurality of the individual electrodes that are located closer to the distal end side of the flat flexible cable than the main electrode region are continuously arranged. An electrode row, and a second individual electrode row having a region in which a plurality of the individual electrodes are continuously arranged, the auxiliary electrode region being closer to the base end side of the flat flexible cable than the main electrode region, Two first individual electrode rows and two second individual electrode rows may be alternately arranged. As a result, a wide area between the terminals can be ensured in a wide range within the terminal distribution area, so that a wide range of margins can be provided for the wiring width and spacing in the flat flexible cable. In addition, there are two types: an individual electrode in which the auxiliary electrode region is on the distal end side of the flat flexible cable with respect to the main electrode region, and an individual electrode in which the auxiliary electrode region is on the proximal end side of the flat flexible cable with respect to the main electrode region. It becomes possible to arrange regularly. Therefore, the pattern design of the individual electrode is facilitated.

  Further, in the present invention, the main electrode region is disposed at a position facing the pressure chamber, the planar shape of the pressure chamber is a parallelogram shape having two acute angle portions, and the intersecting direction is the It is preferable to be parallel to the shorter diagonal of the pressure chamber. As a result, the pressure chambers can be arranged with high density.

  In another aspect of the ink jet head of the present invention, a plurality of pressure chambers each communicating with a nozzle are arranged along a plane, and an ink flow path from an ink supply port to the nozzle through the pressure chamber And a plurality of individual electrodes each having a main electrode region and an auxiliary electrode region connected to the main electrode region, and a volume of the pressure chamber fixed to the plane of the flow channel unit. And a flexible flexible cable having a plurality of terminals electrically connected to the auxiliary electrode region and a plurality of wires respectively connected to the plurality of terminals extending in one direction. It has. In the flow path unit, a plurality of pressure chambers in which a plurality of the pressure chambers having a parallelogram-shaped planar shape having two acute angle portions are arranged in a direction crossing the one direction are parallel to each other. In the actuator unit, the individual electrode in which the main electrode region is arranged facing the pressure chamber forms a plurality of individual electrode rows parallel to each other, and in all the individual electrode rows The auxiliary electrode region is located on the distal end side of the flat flexible cable with respect to the main electrode region, and the auxiliary electrode region is located on the proximal end side of the flat flexible cable with respect to the main electrode region. Individual electrodes are arranged alternately. Thereby, the width and interval of the wiring connected to each of the terminals formed corresponding to all the individual electrode rows can be uniformly increased over the entire area. Therefore, it becomes easier to produce a flat flexible cable. Correspondingly, the pressure chambers can also be arranged with high density.

In the present invention , the intersecting direction is preferably parallel to the shorter diagonal line of the pressure chamber. As a result, the pressure chambers can be arranged with high density.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is an external perspective view of an inkjet head according to an embodiment of the present invention. FIG. 2 is a cross-sectional view taken along the line II-II in FIG. 1 and shows a state in which the head body is assembled to a holder constituting the inkjet head. FIG. 3 is a perspective view showing a state in which a reinforcing plate is bonded to the head body shown in FIG. The ink-jet head 1 is used in a serial-type ink-jet printer (not shown) and records by ejecting ink of four colors, magenta, yellow, cyan and black, onto a sheet conveyed in parallel in the sub-scanning direction. To do. As shown in FIGS. 1 and 2, the inkjet head 1 includes an ink tank 71 in which four ink chambers 3 for storing four color inks are formed, and a head body 70 disposed below the ink tank 71. It has.

  Inside the ink tank 71, four ink chambers 3 are formed side by side in the main scanning direction, and magenta, yellow, cyan, and black inks are sequentially stored from the left ink chamber 3 in FIG. . In these four ink chambers 3, corresponding ink cartridges (not shown) are respectively connected by tubes 40 (see FIG. 1), and ink of each color is supplied from the ink cartridges to the ink chamber 3. Yes. Further, as shown in FIGS. 2 and 3, the ink tank 71 is assembled to a reinforcing plate 41 having a planar rectangular shape. The reinforcing plate 41 is fixed to a holder 72 having a substantially rectangular parallelepiped shape with an ultraviolet curing agent 43. Further, as shown in FIG. 3, the reinforcing plate 41 is formed with an opening 42 having a rectangular planar shape, and an actuator unit 21 described later is disposed in the opening 42. Is fixed by bonding. At the lower end of the ink tank 71, four ink outlets 3a communicating with the four ink chambers 3 are formed. On the other hand, as shown in FIG. 3, the reinforcing plate 41 is formed with four through-holes 41a each having an elliptical planar shape connected to the four ink outlets 3a.

  The head main body 70 includes a flow path unit 4 in which a plurality of ink flow paths are formed for each color, and an actuator unit 21 bonded to the upper surface of the flow path unit 4 with an epoxy-based thermosetting adhesive. It is out. The flow path unit 4 and the actuator unit 21 are configured by laminating a plurality of thin plates and bonding them together. The flow path unit 4 and the actuator unit 21 are disposed below the ink tank 71. On the upper surface of the flow path unit 4, four ink supply ports 4a (see FIG. 4) having an elliptical planar shape are formed. Further, as shown in FIG. 3, the flow path unit 4 is bonded to the reinforcing plate 41 so that the through holes 41 a formed in the reinforcing plate 41 and the ink supply ports 4 a formed in the flow path unit 4 are connected to each other. Has been. With this configuration, four types of ink in the ink tank 71 pass through the four ink outlets 3a formed in the ink tank 71 and the four through holes 41a formed in the reinforcing plate 41, respectively. The ink is supplied from the four ink supply ports 4 a of the unit 4 into the flow path unit 4.

  The head body 70 has a reinforcing plate 41 attached to a stepped opening 72 a formed on the lower surface of the holder 72 in a state where the ink discharge surface 70 a of the flow path unit 4 is exposed to the outside. 72 and the flow path unit 4 are sealed with a sealant 73. The bottom surface of the head main body 70 is an ink ejection surface 70a on which a large number of nozzles 8 (see FIG. 6) having a minute diameter are arranged. A flexible printed circuit (FPC) 50 as a power supply member is joined to the upper surface of the actuator unit 21 and pulled out in one of the main scanning directions, and is pulled out upward while being bent. A protective plate 44 that protects the FPC 50 and the actuator unit 21 is attached to the upper surface of the FPC 50 that faces the actuator unit 21.

  The FPC 50 joined to the actuator unit 21 is pulled out along the side surface of the ink tank 71 through an elastic member 74 such as a sponge, and a driver IC 75 is installed on the FPC 50. On the other hand, the FPC 50 is electrically joined by soldering so as to transmit the drive signal output from the driver IC 75 to the actuator unit 21 (described later in detail) of the head main body 70.

  In FIG. 2, an opening 72b for radiating the heat of the driver IC 75 to the outside is formed on the side wall of the holder 72 facing the driver IC 75. Further, a heat sink 76 made of an approximately rectangular parallelepiped aluminum plate is disposed between the driver IC 75 and the opening 72 b of the holder 72 so as to be in close contact with the driver IC 75. The heat generated by the driver IC 75 can be efficiently dissipated by the heat sink 76 and the opening 72b. In addition, a sealant 77 for filling a gap between the side wall of the holder 72 and the heat sink 76 is disposed in the opening 72b to prevent dust and ink from entering the main body of the inkjet head 1.

  FIG. 4 is a plan view of the head body 70. As shown in FIG. 4, the head main body 70 has a rectangular planar shape extending in the sub-scanning direction. In FIG. 4, four manifold channels 5 extending in parallel with each other along the longitudinal direction of the channel unit 4 are formed in the channel unit 4. Ink is supplied to the manifold channels 5 from the ink chamber 3 of the ink tank 71 through the four ink supply ports 4 a of the channel unit 4. In the present embodiment, manifold channels 5M, 5Y, 5C, and 5K corresponding to magenta, yellow, cyan, and black are formed in order from the manifold channel 5 shown in the upper part of FIG. 4 to the lower part. A filter member 45 is disposed at a position on the upper surface of the flow path unit 4 so as to cover the four ink supply ports 4a. The filter member 45 has a filter 45a in which a plurality of minute holes are formed at positions overlapping with the ink supply ports 4a. Thus, dust in the ink flowing from the ink tank 71 into the flow path unit 4 is captured by the filter 45 a of the filter member 45.

  On the upper surface of the flow path unit 4, an actuator unit 21 having a rectangular planar shape is bonded to a substantially central portion avoiding the ink supply port 4a. The lower surface of the flow path unit 4 corresponding to the adhesion area between the actuator unit 21 and the flow path unit 4 is an ink discharge area in which a large number of nozzles 8 (see FIG. 6) are arranged. A large number of pressure chambers 10 (see FIG. 6) arranged in a matrix are formed in the adhesion region of the flow path unit 4 facing the actuator unit 21. In other words, the actuator unit 21 has dimensions over all the pressure chambers 10.

  FIG. 5 is an enlarged view of a region surrounded by a one-dot chain line drawn in FIG. The pressure chamber 10 formed in the flow path unit 4 has a substantially rhombic planar shape with rounded corners, and the longer diagonal line is the width direction (main scanning direction) of the flow path unit 4. Parallel to By forming the pressure chamber 10 in such a shape, the pressure chambers 10 can be arranged with high density as will be described later. One end of each pressure chamber 10 communicates with the nozzle 8, and the other end communicates with the manifold channel 5 via the aperture 13. Each manifold channel 5 communicates with the nozzle 8 and communicates with each pressure chamber. A large number of individual ink flow paths 7 (see FIG. 6) formed every 10 are connected. In FIG. 5, the pressure chamber 10, the aperture 13, the nozzle 8, and the like that are in the flow path unit 4 and should be drawn with broken lines are drawn with solid lines for easy understanding of the drawing.

  6 is a cross-sectional view showing the individual ink flow path, and is a cross-sectional view taken along the line VI-VI shown in FIG. The aperture 13 communicates with one acute angle portion of the pressure chamber 10, and the nozzle 8 for ejecting ink communicates with the other acute angle portion. As can be seen from FIG. 6, each nozzle 8 communicates with the manifold flow path 5 via the pressure chamber 10 and the aperture (that is, the restriction) 13 to form a flow path corresponding to the pressure chamber 10. In this way, a plurality of individual ink channels 7 that are channels for each pressure chamber 10 are formed in the head main body 70.

  As shown in FIG. 6, the head main body 70 is composed of a total of ten sheet materials including an actuator unit 21, a cavity plate 22, a base plate 23, an aperture plate 24, a supply plate 25, manifold plates 26 to 29 and a nozzle plate 30. Have a laminated structure. Among these, the flow path unit 4 is composed of nine plates excluding the actuator unit 21.

  As will be described in detail later, the actuator unit 21 is a layer in which four piezoelectric sheets 14 to 17 (see FIG. 7) are laminated and only the uppermost layer thereof has a portion that becomes an active portion when an electric field is applied (hereinafter, The remaining three layers are non-active layers that do not have an active portion. The cavity plate 22 is a metal plate in which a large number of substantially rhombic holes constituting the gap of the pressure chamber 10 are provided within the pasting range of the actuator unit 21. The base plate 23 is a metal plate provided with a communication hole between the pressure chamber 10 and the aperture 13 and a communication hole from the pressure chamber 10 to the nozzle 8 for one pressure chamber 10 of the cavity plate 22.

  The aperture plate 24 is a metal plate provided with a communication hole from the pressure chamber 10 to the nozzle 8 in addition to the hole serving as the aperture 13 for one pressure chamber 10 of the cavity plate 22. The supply plate 25 is a metal plate provided with a communication hole between the aperture 13 and the manifold channel 5 and a communication hole from the pressure chamber 10 to the nozzle 8 for one pressure chamber 10 of the cavity plate 22. The manifold plates 26 to 29 are metal plates each provided with a communication hole from the pressure chamber 10 to the nozzle 8 for one pressure chamber 10 of the cavity plate 22 in addition to the manifold flow path 5. The nozzle plate 30 is a metal plate in which the nozzles 8 are provided for one pressure chamber 10 of the cavity plate 22.

  These ten sheets 21 to 30 are laminated in alignment with each other so that the individual ink flow paths 7 as shown in FIG. 6 are formed. The individual ink flow path 7 is first directed upward from the manifold flow path 5, extends horizontally at the aperture 13, then further upwards, extends horizontally again at the pressure chamber 10, and then leaves the aperture 13 for a while. Heading diagonally downward in the direction and then vertically downward toward the nozzle 8.

  As is clear from FIG. 6, the pressure chamber 10 and the aperture 13 are provided at different levels in the stacking direction of the plates. As a result, as shown in FIG. 5, in the flow path unit 4 facing the actuator unit 21, the aperture 13 communicating with one pressure chamber 10 is seen in plan view with another pressure chamber 10 adjacent to the pressure chamber. It can be arranged at the same position. As a result, the pressure chambers 10 are in close contact with each other and are arranged at high density, so that high-resolution image printing is realized by the inkjet head 1 having a relatively small occupation area.

  Returning to FIG. 5, each of the plurality of pressure chambers 10 communicates with the nozzle 8 at one end of the long diagonal line, and communicates with the manifold channel 5 through the aperture 13 at the other end of the long diagonal line. As will be described later, on the actuator unit 21, individual electrodes 35 (see FIG. 7) having a substantially rhombus shape and slightly smaller than the pressure chamber 10 are arranged in a matrix so as to face the pressure chamber 10. Yes. In FIG. 5, only some of the plurality of individual electrodes 35 are drawn for the sake of simplicity.

  The pressure chambers 10 are adjacently arranged in a matrix in two directions of the arrangement direction A (first direction) and the arrangement direction B (second direction), and a plurality of pressure chambers 10 are staggered along the arrangement direction A. It is formed in the shape arrangement pattern. The arrangement direction A is the longitudinal direction of the inkjet head 1, that is, the extending direction of the flow path unit 4, and is parallel to the shorter diagonal line of the pressure chamber 10. The arrangement direction B is an oblique side direction of the pressure chamber 10 that forms an obtuse angle θ with the arrangement direction A. Both acute angle portions of the pressure chamber 10 are located between two adjacent pressure chambers.

  The pressure chambers 10 arranged adjacent to each other in a matrix in two directions of the arrangement direction A and the arrangement direction B are arranged along the arrangement direction A via a gap corresponding to the resolution. For example, in the present embodiment, adjacent pressure chambers 10 are separated along the arrangement direction A by a distance corresponding to 37.5 dpi in order to enable printing with a resolution of 150 dpi. In addition, 16 pressure chambers 10 are arranged in the arrangement direction B in the actuator unit 21 and are orthogonal to the arrangement direction A when viewed from the direction perpendicular to the paper surface of FIG. 5 (the third direction). Eight are arranged along the direction (fourth direction).

  A large number of pressure chambers 10 arranged in a matrix form a plurality of pressure chamber rows 11 along the arrangement direction A shown in FIG. The plurality of pressure chamber rows 11 includes a first pressure chamber row 11a, a second pressure chamber row 11b, and a third pressure chamber according to the relative position with respect to each manifold channel 5 when viewed from the third direction. It is divided into a row 11c and a fourth pressure chamber row 11d. These first to fourth pressure chamber rows 11a to 11d are arranged from one side in the width direction of the actuator unit 21 to the other side (from the lower side to the upper side in FIG. 5), 11c → 11a → 11d → 11b → 11c → 11a → -4 pieces are periodically arranged in the order of 11b. In addition, four pressure chamber groups 12 are formed for each of the first to fourth pressure chamber rows that are periodically arranged by four, and the pressure chambers 10 of each pressure chamber group 12 are connected to each manifold channel 5. And communicate with each other via an aperture 13. That is, since each pressure chamber group 12 is formed for each manifold channel 5, it is divided into pressure chamber groups 12M, 12Y, 12C, and 12K so as to correspond to four colors of ink. The pressure chambers 10 belonging to each of the four pressure chamber groups 12M, 12Y, 12C, and 12K are subjected to volume change by the actuator unit 21 so that four color inks are ejected from the nozzles 8 communicating with the respective pressure chamber groups 12. Is possible.

  In the pressure chambers 10a constituting the first pressure chamber row 11a and the pressure chambers 10c constituting the third pressure chamber row 11c, a direction (fourth direction) orthogonal to the arrangement direction A when viewed from the third direction. ), The nozzle 8 is unevenly distributed on the lower side of the drawing sheet of FIG. The nozzle 8 is adjacent to the vicinity of the left side of the lower end of the corresponding pressure chamber 10 in plan view in FIG. On the other hand, in the pressure chamber 10b constituting the second pressure chamber row 11b and the pressure chamber 10d constituting the fourth pressure chamber row 11d, the nozzle 8 is unevenly distributed on the upper side in FIG. 4 in the fourth direction. Yes. The nozzles 8 are adjacent to the vicinity of the right side of the upper end portion of the corresponding pressure chamber 10 in plan view in FIG. In the first and fourth pressure chamber rows 11 a and 11 d, the region of more than half of the pressure chambers 10 a and 10 d overlaps the manifold channel 5 when viewed from the third direction. In the second and third pressure chamber rows 11b and 11c, almost all the regions of the pressure chambers 10b and 10c do not overlap the manifold channel 5a when viewed from the third direction. Therefore, for the pressure chambers 10 belonging to any pressure chamber row, the width of the manifold channel 5 is made as wide as possible while preventing the nozzle 8 communicating therewith from overlapping with the manifold channel 5a. Ink can be supplied smoothly.

  A plurality of gaps 60 are formed in the cavity plate 22 of the flow path unit 4 at positions that overlap with the area between the manifold flow path 5C and the manifold flow path 5K. The plurality of gaps 60 are arranged adjacent to each other in two directions of the arrangement direction A and the arrangement direction B in the same manner as the pressure chamber 10. The plurality of gaps 60 along the arrangement direction A form four rows of gaps 61 parallel to each other, and these four rows of gaps 61 constitute a gap group 62. The plurality of gaps 60 of the gap group 62 are defined by the holes having the same shape and the same size as the pressure chambers 10 formed in the cavity plate 22 being closed by the actuator unit 21 and the base plate 23. That is, since the ink flow path is not connected to the gap 60, the plurality of gaps 60 are not filled with ink. Further, on the ink discharge surface 70 a of the flow path unit 4, the nozzle connected to the gap 60 is not formed at a position facing the gap group 62, so that the ink discharge area formed on the ink discharge surface 70 a uses black ink. It is divided into a black area to be ejected and a color area to eject magenta, yellow and cyan inks. As described above, the ink discharge area is divided into the color area and the black area, so that it is easy to dispose a cap for purging only the black ink. The reason why the gap group 62 is formed in the cavity plate 22 is to improve ink ejection characteristics by making the rigidity uniform with respect to the pressure chamber 10 that ejects ink.

  Next, the configuration of the actuator unit 21 will be described. On the actuator unit 21, a large number of individual electrodes 35 are arranged in a matrix with the same arrangement pattern as the pressure chambers 10. Each individual electrode 35 is disposed at a position facing the pressure chamber 10 in plan view. In this way, the plurality of pressure chambers 10 and the individual electrodes 35 are regularly arranged, so that the design is facilitated.

  7A and 7B show the actuator unit, in which FIG. 7A is an enlarged view of a portion surrounded by an alternate long and short dash line in FIG. 6, and FIG. 7B is a plan view of an individual electrode. FIG. 8 is an enlarged view showing a region surrounded by a two-dot chain line shown in FIG. In FIG. 7A, the FPC 50 electrically connected to each individual electrode 35 is drawn with a two-dot chain line. In order to make FIG. 8 easy to understand, the individual electrodes 35 of the actuator unit 21, the terminals 46 of the FPC 50, and the wirings 48, which are originally drawn with broken lines, are drawn with solid lines. As shown in FIGS. 7A and 7B, the individual electrode 35 is disposed at a position facing the pressure chamber 10, and a main electrode region 35a formed in the plane region of the pressure chamber 10 in plan view. The auxiliary electrode region 35 b is connected to the main electrode region 35 a and is formed outside the plane region of the pressure chamber 10.

  As shown in FIG. 7A, the actuator unit 21 includes four piezoelectric sheets 14, 15, 16, and 17 formed to have the same thickness of about 15 μm. The piezoelectric sheets 14 to 17 are continuous layered flat plates (continuous flat plate layers) so as to be disposed across a large number of pressure chambers 10 formed in the ink discharge region in the head main body 70. Since the piezoelectric sheets 14 to 17 are arranged as a continuous flat plate layer across a large number of pressure chambers 10, the individual electrodes 35 can be arranged on the piezoelectric sheet 14 at a high density by using, for example, a screen printing technique. It has become. For this reason, the pressure chambers 10 formed at positions corresponding to the individual electrodes 35 can be arranged with high density, and high-resolution images can be printed. The piezoelectric sheets 14 to 17 are made of a lead zirconate titanate (PZT) ceramic material having ferroelectricity.

  As shown in FIG. 7B, the main electrode region 35a of the individual electrode 35 formed on the uppermost piezoelectric sheet 14 has a substantially rhombic planar shape that is substantially similar to the pressure chamber 10. One acute angle portion of the substantially rhomboid main electrode region 35a extends and is connected to the auxiliary electrode region 35b. A circular land portion 36 electrically connected to the individual electrode 35 is provided at the tip of the auxiliary electrode region 35b. As shown in FIG. 7B, the land portion 36 faces a region where the pressure chamber 10 is not formed in the cavity plate 22. The land portion 36 is made of, for example, gold containing glass frit, and is formed on the surface of the auxiliary electrode region 35b as shown in FIG.

  As shown in FIG. 8, the plurality of individual electrodes 35 form a plurality of individual electrode rows 37 arranged in parallel with each other along the arrangement direction A in the same manner as the pressure chamber row 11. In the adjacent individual electrode rows 37, the individual electrodes 35 in another row are arranged between the adjacent individual electrodes 35 in the row. It is just shifted by ½ of the arrangement interval (pitch) of the individual electrodes 35 in the arrangement direction A. Overall, a plurality of individual electrodes 35 are formed in a staggered arrangement pattern along the arrangement direction A. That is, the plurality of individual electrodes 35 along the fourth direction form a plurality of individual electrode rows parallel to each other, and the individual electrodes 35 belonging to two adjacent individual electrode rows belong to different individual electrode columns 37. Yes. The plurality of individual electrode rows 37 are divided into individual electrode rows 37a to 37d corresponding to the pressure chamber rows 11a to 11d. With these individual electrode rows 37a to 37d as one group, four individual electrode groups 38 corresponding to the four pressure chamber groups 12 are configured. Each individual electrode row 37 includes an individual electrode 35 in which the auxiliary electrode region 35b is formed on the base end side (lower side in FIG. 8) of the FPC 50 with respect to the main electrode region 35a, and the auxiliary electrode region 35b in the main electrode region 35a. On the other hand, an individual electrode 35 formed on the front end side (upper side in FIG. 8) of the FPC 50 is included. In the arrangement direction A, the auxiliary electrode regions 35b are arranged so as to alternately face the proximal end side and the distal end side of the FPC 50. Further, in the individual electrode group 38, also in the arrangement direction B, the auxiliary electrode regions 35b are arranged so as to alternately face the proximal end side or the distal end side of the FPC 50. That is, as shown in FIG. 8, in the individual electrode rows, the auxiliary electrode regions 35b are alternately arranged along the fourth direction with the individual electrodes 35 on the proximal end side of the FPC 50 and the individual electrodes 35 on the distal end side. ing.

  In the present embodiment, four rows of gaps 61 in which the arrangement of the individual electrodes 35 is unnecessary are interposed between the region for discharging the color ink (color region) and the region for discharging the black ink (black region). . However, the regularity of the arrangement of the auxiliary electrode regions 35b in the row is continuous across these two regions. Even when the gap row 61 is not interposed, the continuity of such regularity is important, and the wiring of the FPC 50 can be routed at a reasonable interval over the entire region where the individual electrodes 35 are disposed. Note that when the individual electrode rows straddle a plurality of regions as in the present embodiment, the above-described regularity may be discontinuous between the regions. That is, the intervening individual electrode unnecessary region becomes a kind of buffer region, and the wiring interval of the FPC 50 is not restricted.

  Returning to FIG. 7, a common electrode 34 having the same outer shape as the piezoelectric sheet 14 and a thickness of approximately 2 μm is interposed between the uppermost piezoelectric sheet 14 and the lower piezoelectric sheet 15. Both the individual electrode 35 and the common electrode 34 are made of, for example, a metal material such as an Ag—Pd system.

  The common electrode 34 is grounded in a region not shown. As a result, the common electrode 34 is kept at an equally constant potential in the region corresponding to all the pressure chambers 10, that is, the ground potential in the present embodiment.

  As shown in FIG. 7A, the FPC 50 includes a base film 49, a plurality of wirings 48 formed on the lower surface thereof, and a cover film 52 that covers substantially the entire lower surface of the base film 49. The base film 49 has a thickness of approximately 25 μm, the wiring 48 has a thickness of approximately 9 μm, and the cover film 52 has a thickness of approximately 20 μm. A plurality of through holes 53 having an area smaller than the wiring 48 are formed in the cover film 52 corresponding to the land portions 36 formed in the actuator unit 21. The base film 49, the wiring 48, and the cover film 52 are aligned with each other so that the center of each through-hole 53 corresponds to the center line of the wiring 48 and the outer peripheral edge of the wiring 48 is covered with the cover film 52. Are stacked. The terminal 46 of the FPC 50 is connected to the wiring 48 through the through hole 53.

  The base film 49 and the cover film 52 are both sheet members having insulation properties. In the present embodiment, the base film 49 is made of a polyimide resin, and the cover film 52 is made of a photosensitive material. By forming the cover film 52 from a photosensitive material in this way, it becomes easy to form a large number of through holes 53.

  The wiring 48 is formed of copper foil. The wiring 48 is a wiring connected to the driver IC 75, and forms a predetermined pattern on the lower surface of the base film 49.

  The terminal 46 is made of a conductive material such as nickel. The terminal 46 closes the through hole 53, covers the outer periphery of the through hole 53, and projects from the lower surface of the cover film 52. The diameter of the terminal 46 is about 50 μm, and the thickness from the lower surface of the cover film 40 is about 30 μm.

  As shown in FIG. 8, a plurality of terminals 46 of the FPC 50 are provided at positions facing the land portions 36 of the individual electrodes 35, and each terminal 46 is configured to be able to be joined to one land portion 36. Yes. Each terminal 46 has a wiring 48 drawn in one direction (the width direction of the flow path unit 4 and the main scanning direction) toward the base end side and the tip end side of the FPC 50, and is drawn out to the base end side of the FPC 50. Each terminal 46 is independently connected to the driver IC 75 by the wiring 48. As a result, the potential can be controlled for each pressure chamber 10. In the FPC 50 according to the present embodiment, since the solder plating for connecting to the land portion 36 is applied to the terminal 46 of the FPC 50 by electrolytic plating, the wiring 48 extends from the terminal 46 toward the proximal end side and the distal end side of the FPC 50. It has been pulled out. In addition, after solder plating is performed on each terminal 46 of the FPC 50, the tip side portion of the FPC 50 is cut leaving a portion facing the actuator unit 21 of the FPC 50 (a region where the plurality of terminals 46 of the FPC 50 are formed) It is in the form of an FPC 50 as shown in FIG.

  Further, among the plurality of wirings 48 drawn out from each terminal 46 of the FPC 50, the wirings 48 other than the wiring 48 drawn out from the terminal 46 form a wiring non-formation region 39 while avoiding the peripheral region of the terminal 46. Is bent. Further, the wirings 48 drawn out from the respective terminals 46 of the FPC 50 are arranged at almost equal intervals in a region sandwiched between the peripheral regions of the terminals 46.

  Next, a method for driving the actuator unit 21 will be described. The polarization direction of the piezoelectric sheet 14 in the actuator unit 21 is the thickness direction thereof. In other words, the actuator unit 21 includes the upper piezoelectric element 14 (that is, away from the pressure chamber 10) as a layer in which the active portion exists and the lower piezoelectric element 10 (that is, close to the pressure chamber 10). It has a so-called unimorph type structure in which 15 to 17 are inactive layers. Therefore, when the individual electrode 35 is set to a positive or negative predetermined potential, for example, if the electric field and polarization are in the same direction, the electric field application portion sandwiched between the electrodes in the piezoelectric sheet 14 acts as an active portion (pressure generating portion), Shrink in the direction perpendicular to the polarization direction due to the piezoelectric transverse effect.

  In the present embodiment, the portion sandwiched between the individual electrode 35 and the common electrode 34 in the piezoelectric sheet 14 functions as an active portion that generates distortion due to the piezoelectric effect when an electric field is applied. On the other hand, the three piezoelectric sheets 15 to 17 below the piezoelectric sheet 14 are not applied with an electric field from the outside, and therefore hardly function as active parts. Therefore, a portion of the piezoelectric sheet 14 sandwiched mainly between the main electrode region 35a and the common electrode 34 is contracted in a direction perpendicular to the polarization direction due to the piezoelectric lateral effect.

  On the other hand, since the piezoelectric sheets 15 to 17 are not affected by the electric field and are not spontaneously displaced, the piezoelectric sheets 15 to 17 are not displaced in the direction perpendicular to the polarization direction between the upper piezoelectric sheet 14 and the lower piezoelectric sheets 15 to 17. A difference is caused in the distortion, and the whole piezoelectric sheets 14 to 17 try to be deformed so as to be convex on the non-active side (unimorph deformation). At this time, as shown in FIG. 7A, the lower surface of the actuator unit 21 constituted by the piezoelectric sheets 14 to 17 is fixed to the upper surface of the partition wall (cavity plate) 22 that partitions the pressure chamber. Specifically, the piezoelectric sheets 14 to 17 are deformed so as to protrude toward the pressure chamber. For this reason, the volume of the pressure chamber 10 is reduced, the pressure of the ink is increased, and the ink is ejected from the nozzle 8. Thereafter, when the individual electrode 35 is returned to the same potential as that of the common electrode 34, the piezoelectric sheets 14 to 17 return to the original shape and the volume of the pressure chamber 10 returns to the original volume, so that ink is sucked from the manifold channel 5 side. .

  As another driving method, the individual electrode 35 is set to a potential different from that of the common electrode 34 in advance, and the individual electrode 35 is once set to the same potential as the common electrode 34 every time there is an ejection request, and then again individually at a predetermined timing. The electrode 35 can be at a different potential from the common electrode 34. In this case, when the individual electrodes 35 and the common electrode 34 are at the same potential, the piezoelectric sheets 14 to 17 return to the original shape, so that the volume of the pressure chamber 10 is in an initial state (the potentials of the two electrodes are different). ) And the ink is sucked into the pressure chamber 10 from the manifold channel 5 side. Thereafter, at the timing when the individual electrode 35 is set to a potential different from that of the common electrode 34 again, the piezoelectric sheets 14 to 17 are deformed so as to protrude toward the pressure chamber 10, and the pressure on the ink increases due to the volume reduction of the pressure chamber 10. Ink is ejected. In this way, ink is ejected from the nozzles 8 and the inkjet head 1 is appropriately moved in the main scanning direction to print a desired image on the paper.

  According to the ink jet head 1 as described above, it is possible to make the interval between the plurality of wirings 48 drawn from the terminals 46 of the FPC 50 electrically connected to the plurality of individual electrodes 35 of the actuator unit 21 relatively large. become. That is, as shown in FIG. 8, in the individual electrode row 37c of the actuator unit 21 closest to the base end side of the FPC 50, the auxiliary electrode region 35b has the individual electrode 35 on the tip side of the FPC 50 with respect to the main electrode region 35a, The auxiliary electrode regions 35b alternately exist with the individual electrodes 35 on the base end side of the FPC 50 with respect to the main electrode region 35a. Therefore, the distance between the adjacent auxiliary electrode regions 35b is doubled compared to the case where the auxiliary electrode regions 35b of the adjacent individual electrodes 35 are arranged in the same direction as in the above publication. That is, in the individual electrode row 37c, when considering the three individual electrodes 35 adjacent to each other, the auxiliary electrode region 35b is sandwiched between the two individual electrodes 35 on the proximal end side of the FPC 50 with respect to the main electrode region 35a. Since the auxiliary electrode region 35b of the individual electrode 35 is on the tip side of the FPC 50, the distance between the adjacent auxiliary electrode regions 35b in the direction parallel to the arrangement direction A becomes longer. Therefore, the width and interval of the wirings 48 connected to each terminal 46 of the FPC 50 formed corresponding to the individual electrode 35 closest to the base end of the FPC 50 can be increased. Therefore, when the FPC 50 is manufactured, the interval between the wirings 48 of the FPC 50 is widened, so that the manufacture becomes easy. Moreover, it is not necessary to increase the size of the actuator unit to increase the interval between the land portions 36 of the individual electrodes 35 to increase the interval between the terminals 46 of the FPC 50 connected to the land portion 36 and increase the interval between the wirings 48. An increase in the size of can also be prevented. In addition, it is possible to easily cope with higher image resolution and higher pressure chamber density.

  Further, in all the individual electrode rows 37 formed in the actuator unit 21 of the inkjet head 1, the auxiliary electrode region 35b is mainly provided with the individual electrode 35 on the front end side of the FPC 50 with respect to the main electrode region 35a and the auxiliary electrode region 35b. Since the individual electrodes 35 on the base end side of the FPC 50 are alternately present with respect to the electrode region 35a, the width of the wiring 48 connected to each of the terminals 46 formed corresponding to all the individual electrode rows. And the interval can be evenly widened over the entire area. Therefore, the manufacture of the FPC 50 is further facilitated. Further, the degree of freedom of the planar shape of the pressure chamber group 12 composed of the plurality of pressure chambers 10 is increased. That is, in any individual electrode row formed by the individual electrodes 35, the arrangement direction of the pressure chamber group formed by the plurality of pressure chambers 10 respectively facing the plurality of individual electrodes 35 is any plane shape. If the auxiliary electrode regions 35b are alternately arranged along the line A, the distance between the land portions 36 of the auxiliary electrode region 35b increases, so that the distance between the terminals 46 of the FPC 50 also increases and the width of the wiring 48 drawn from the terminal 46 increases. Spacing increases. Furthermore, in the present embodiment, the wiring 48 is drawn out substantially orthogonal to the direction in which the individual electrode rows extend. This contributes to the fact that a larger number of wirings 48 can be disposed without reducing the wiring width or wiring interval even if the same land portion 36 has the same width.

  In the inkjet head 1 according to the present embodiment, the plurality of individual electrode rows 37 formed by the plurality of individual electrodes 35 formed in the actuator unit 21 has the auxiliary electrode region 35b with respect to the main electrode region 35a. The individual electrodes 35 on the side and the individual electrodes 35 in which the auxiliary electrode regions 35b are on the proximal end side of the FPC 50 with respect to the main electrode region 35a are alternately arranged. Thereby, the same width of the land portion 36 can be increased, and the high-density and high-resolution inkjet head 1 can be obtained.

  Subsequently, an inkjet head according to another embodiment of the present invention will be described below. FIG. 9 is an external perspective view of an inkjet head according to another embodiment of the present invention. 10 is a cross-sectional view taken along line XX in FIG. As shown in FIG. 9, the inkjet head 100 includes a head body 170 having a rectangular planar shape extending in the main scanning direction for ejecting ink onto a sheet, and two head bodies 170 disposed above the head body 170. A base block 171 in which the ink reservoir 103 is formed and an FPC 150 joined to the upper surface of the head main body 170 are included.

  As shown in FIG. 10, the head main body 170 includes a flow path unit 104 in which an ink flow path is formed, and a plurality of actuator units 121 bonded to the upper surface of the flow path unit 104 with an epoxy thermosetting adhesive. Is included. The flow path unit 104 has a configuration in which a plurality of thin plates are stacked and bonded to each other. The bottom surface of the head main body 170 is an ink ejection surface 170a on which a large number of nozzles 108 (see FIG. 13) having a minute diameter are arranged. Further, the FPC 150 is joined to the upper surface of the actuator unit 121 and pulled out to the left or right, and the FPC 150 is pulled upward while being bent in FIG.

  FIG. 11 is a plan view of the head main body 170 to which the FPC 150 is bonded as seen from above. As shown in FIG. 11, the flow path unit 104 has a rectangular planar shape extending in the main scanning direction, and a manifold flow path 105 is provided therein. The manifold channel 105 is branched into a plurality of sub-manifold channels 105a extending in parallel with the longitudinal direction (main scanning direction) of the channel unit 4, and ink from the base block 171 is opened (ink supply port). ) 103a.

  On the upper surface of the flow path unit 104, four actuator units 121 having a trapezoidal planar shape are arranged in a zigzag manner and bonded in two rows so as to avoid the openings 103a. Each actuator unit 121 is arranged such that its parallel opposing sides (upper side and lower side) are along the longitudinal direction of the flow path unit 104. The plurality of openings 103 a are arranged in two rows along the longitudinal direction of the flow path unit 104, and a total of ten openings 103 a in each row are provided at positions where they do not interfere with the actuator unit 121. The oblique sides of the adjacent actuator units 121 partially overlap in the width direction (sub-scanning direction) of the flow path unit 104.

  On the ink discharge surface 170a, an ink discharge region is formed by arranging a large number of nozzles 108 in a matrix for each region corresponding to the adhesion region of the actuator unit 121. In the adhesion region of each actuator unit 121, a number of pressure chambers 110 (see FIG. 13) are arranged in a matrix to form a pressure chamber group 109. In other words, the actuator unit 121 has a dimension that spans a large number of pressure chambers 110 constituting the pressure chamber group 109.

  Returning to FIG. 10, the base block 171 is made of a metal material such as stainless steel. The ink reservoir 103 in the base block 171 is a substantially rectangular parallelepiped hollow region extending along the longitudinal direction of the base block 171. The ink reservoir 103 is supplied with ink from an ink tank (not shown) installed outside through an opening (not shown) provided at one end thereof, and is always filled with ink. The ink reservoir 103 is provided with a total of ten openings 103b for discharging ink in two rows along the extending direction. These openings 103 b are provided in a staggered manner so as to be connected to the openings 103 a of the flow path unit 104. That is, the ten openings 103b of the ink reservoir 103 and the ten openings 103a of the flow path unit 104 are provided to have the same positional relationship in plan view.

  The lower surface 173 of the base block 171 protrudes downward from the periphery in the vicinity 173a of the opening 103b. The base block 171 is in contact with the vicinity of the opening 103a of the flow path unit 104 only at the vicinity 173a. Therefore, a region other than the vicinity portion 173a of the opening 103b is separated from the head main body 170, and the actuator unit 121 is disposed in this separated portion. In the present embodiment, a predetermined gap is left between the FPC 150 connected to the actuator unit 121 and the lower surface 173.

  The holder 172 includes a gripping portion 172a that grips the base block 171 and a pair of projecting portions 172b that are provided at intervals in the sub-scanning direction and project upward from the upper surface of the gripping portion 172a. The base block 171 is adhesively fixed in a recess formed in the lower surface of the grip portion 172a of the holder 172. The FPCs 150 connected to the actuator unit 121 are respectively arranged along the surface of the protruding portion 172b of the holder 172 via an elastic member 183 such as a sponge. A driver IC 180 is installed on the FPC 150 arranged on the surface of the protrusion 172b of the holder 172. The FPC 150 transmits a drive signal output from the driver IC 180 to the actuator unit 121 of the head main body 170, and the actuator unit 121 and the driver IC 180 are electrically joined by soldering.

  Since the heat sink 182 having a substantially rectangular parallelepiped shape is closely disposed on the outer surface of the driver IC 180, the heat generated by the driver IC 180 can be efficiently dissipated. A substrate 181 connected to the outside of the FPC 150 is disposed above the driver IC 180 and the heat sink 182. The upper surface of the heat sink 182 and the substrate 181 and the lower surface of the heat sink 182 and the FPC 150 are bonded by seal members 184, respectively, to prevent dust and ink from entering the main body of the inkjet head 100. Yes.

  FIG. 12 is an enlarged plan view of a region surrounded by a dashed line drawn in FIG. As shown in FIG. 12, four sub-manifold channels 105 a extend in parallel to the longitudinal direction (main scanning direction) of the channel unit 104 in a region facing the actuator unit 121 in the channel unit 104. ing. A large number of individual ink channels 107 similar to the above-described individual ink channels 7 communicating with each of the nozzles 108 are connected to each sub-manifold channel 105a (see FIG. 13).

  The pressure chamber group 109 on the upper surface of the flow path unit 104 has a trapezoidal shape that is almost the same size as the outer shape of the actuator unit 121, and one pressure chamber is formed for each actuator unit 121. Each pressure chamber 110 belonging to the pressure chamber group 109 communicates with the nozzle 108 at one end (one acute angle portion) of the long diagonal, and communicates with the aperture 112 at the other end (the other acute angle portion) of the long diagonal. ing. As will be described later, on the actuator unit 121, individual electrodes 135 (see FIG. 14) whose planar shape is approximately rhombus and slightly smaller than the pressure chamber 110 are arranged in a matrix so as to face the pressure chamber 110. Yes. In FIG. 12, the actuator unit 121, the pressure chamber 110 (pressure chamber group 109), the aperture 112, and the nozzle 108, which are to be drawn by broken lines below the FPC 150, are drawn by solid lines for easy understanding of the drawing.

13 is a cross-sectional view taken along line XIII-XIII shown in FIG. Head body 170
As shown in FIG. 13, the actuator unit 121, the cavity plate 122, the base plate 123, the aperture plate 124, the supply plate 125, the manifold plates 126, 127, and 128, the cover plate 129, and the nozzle plate 130 are stacked from the top. It has a laminated structure. Among these, the flow path unit 104 is composed of nine plates 122 to 130 excluding the actuator unit 121. Each of these plates 122 to 130 is a metal plate made of stainless steel or the like. The channel unit 104 has substantially the same configuration as the channel unit 4 described above. That is, the pressure plate 110 is provided in the cavity plate 122, the aperture 112 is provided in the aperture plate 124, the sub manifold channel 105a (manifold channel 105) is provided in each of the three manifold plates 126 to 128, and the nozzle 108 is provided in the nozzle plate 130. Each is provided. As shown in FIG. 13, the components of the flow path such as the pressure chamber 110 and the aperture 112 are communicated by through holes formed in each plate, and the individual ink flow path 107 similar to the individual ink flow path 7 is configured. Has been. The individual ink flow path 107 is formed for each pressure chamber 110 in the flow path unit 104. Note that the present embodiment is different in that the manifold plate 29 in the flow path unit 4 described above is replaced with a cover plate 129. The cover plate 129 has no manifold channel opening.

  Returning to FIG. 12, the pressure chambers 110 are adjacently arranged in a matrix in two directions of the arrangement direction E and the arrangement direction F, and a plurality of pressure chambers 110 are formed in a staggered arrangement pattern along the arrangement direction E. ing. The arrangement direction E is the longitudinal direction of the inkjet head 100, that is, the extending direction of the flow path unit 104, and is parallel to the shorter diagonal line of the pressure chamber 110. The arrangement direction F is an oblique side direction of the pressure chamber 110 that forms an obtuse angle θ ′ with the arrangement direction E. Both acute angle portions of the pressure chamber 110 are located between the other two adjacent pressure chambers.

  As shown in FIG. 12, the pressure chambers 110 are arranged along the arrangement direction E by a distance corresponding to 37.5 dpi. 16 pressure chambers 110 are arranged in the arrangement direction F, and eight pressure chambers 110 are arranged along a direction G orthogonal to the arrangement direction E when viewed from the direction perpendicular to the paper surface of FIG. . In one actuator unit 121, 16 pressure chamber rows 111 extending in the arrangement direction E are formed in parallel with each other, and printing can be performed with a resolution of 600 dpi as a whole.

  These 16 pressure chamber rows 111 are adjacent to each other at a predetermined interval, and a pressure chamber group 109 is configured. The pressure chamber row 111 has a first pressure chamber row 111a, a second pressure chamber row 111b, a third pressure chamber row 111, and a third pressure chamber row 111b according to the relative position with respect to the sub-manifold channel 105a as viewed from the direction perpendicular to the paper surface of FIG. Are divided into a pressure chamber row 111c and a fourth pressure chamber row 111d. The first to fourth pressure chamber rows 111a to 111d are periodically arranged in order of 111c → 111d → 111a → 111b → 111c → 111d → ... → 111b from the upper side to the lower side of the actuator unit 21. Has been placed.

  In the pressure chamber 110a constituting the first pressure chamber row 111a and the pressure chamber 110b constituting the second pressure chamber row 111b, the nozzle 108 is located on the lower side with respect to the direction G taken in the direction orthogonal to the arrangement direction E. It is unevenly distributed and faces the vicinity of the lower end of the corresponding pressure chamber 10. On the other hand, in the pressure chamber 110c constituting the third pressure chamber row 111c and the pressure chamber 110d constituting the fourth pressure chamber row 111d, the nozzles 108 are unevenly distributed upward in the direction G, and the corresponding pressure chambers 110 respectively. It faces the vicinity of the upper end of the.

  Next, the actuator unit 121 will be described. The actuator unit 121 has substantially the same configuration as the actuator unit 21 described above. As shown in FIG. 13, four piezoelectric sheets 141 to 144 are laminated, and only the uppermost layer is activated when an electric field is applied. A layer having a part to be a part (hereinafter simply referred to as “layer having an active part”), and the remaining three layers are inactive layers having no active part. On the actuator unit 121, as shown in FIG. 12, individual electrodes 135 (see FIG. 14) whose planar shape is almost diamond-shaped and slightly smaller than the pressure chamber 110 are arranged in a matrix so as to face the pressure chamber 110. Has been. In FIG. 12, only some of the plurality of individual electrodes 135 are drawn for the sake of simplicity, and hatching is applied to them. As described above, since the plurality of pressure chambers 110 and the individual electrodes 135 are regularly arranged, the design is facilitated.

  FIG. 14 is an enlarged view showing a region surrounded by an alternate long and short dash line shown in FIG. In FIG. 14, the individual electrodes 135 on the actuator unit 121, the terminals 146 of the FPC 150, and the wirings 48, which are originally drawn with broken lines, are drawn with solid lines in order to make the drawing easier to understand. As shown in FIGS. 13 and 14, the individual electrode 135 is disposed at a position facing the pressure chamber 110, and a main electrode region 135 a formed in the planar region of the pressure chamber 110 in plan view, and the main electrode region The auxiliary electrode region 135b is connected to the 135a and formed outside the plane region of the pressure chamber 110.

  As shown in FIG. 13, the four piezoelectric sheets 141 to 144 have almost the same thickness. These piezoelectric sheets 141 to 144 are arranged across a large number of pressure chambers 110 formed in the ink discharge region in the head main body 170. Both are made of a ceramic material of lead zirconate titanate (PZT) having ferroelectricity.

  As shown in FIG. 14, the main electrode region 135 a of the individual electrode 135 formed on the uppermost piezoelectric sheet 141 has a substantially rhombic planar shape that is substantially similar to the pressure chamber 110. One acute angle portion of the substantially rhomboid main electrode region 135a extends and is connected to the auxiliary electrode region 135b. A circular land portion 136 that is electrically connected to the individual electrode 135 is provided at the tip of the auxiliary electrode region 135b. The land portion 136 faces a region where the pressure chamber 110 is not formed in the cavity plate 122. The land portion 136 is made of, for example, gold containing glass frit, and is formed on the surface of the auxiliary electrode region 135b as shown in FIG.

  As shown in FIG. 14, the plurality of individual electrodes 135 form a plurality of individual electrode rows 137 arranged in parallel with each other along the arrangement direction E, like the pressure chamber row 111. The plurality of individual electrode rows 137 are divided into individual electrode rows 137a to 137d corresponding to the pressure chamber rows 111a to 111d. Each individual electrode row 137 includes an individual electrode 135 in which the auxiliary electrode region 135b is formed on the base end side (lower side in FIG. 14) of the FPC 150 with respect to the main electrode region 135a, and the auxiliary electrode region 135b in the main electrode region 135a. On the other hand, an individual electrode 135 formed on the front end side (the upper side in FIG. 14) of the FPC 150 is included, and these auxiliary electrode regions 135b are arranged along the arrangement direction E so as to face the base end side or the front end side of the FPC 150. Are alternately arranged. The plurality of individual electrodes 135 form a plurality of individual electrode rows 138 arranged in parallel along the direction G and parallel to each other. Individual electrodes 135 belonging to two adjacent individual electrode rows 138 belong to different individual electrode columns 137. Further, there are two types of individual electrode rows 138 depending on the arrangement direction of the auxiliary electrode regions 135b in the row. The first individual electrode row 138 b is configured by a continuous arrangement of individual electrodes 135 in which the auxiliary electrode region 135 b is formed on the front end side of the FPC 150. On the other hand, the second individual electrode row 138 a is configured by the individual electrode 135 in which the auxiliary electrode region 135 b is formed on the base end side of the FPC 150. The individual electrode rows 138a and the individual electrode rows 138b are alternately arranged two by two along the arrangement direction E. Note that the terminal 146 and the wiring 48 of the FPC 150 are formed corresponding to each auxiliary electrode region 135b (land portion 136). As a result, a portion having a wide terminal interval is distributed over the entire area where the terminals 146 are distributed. Since it can be surely performed regardless of the location, there is a margin in the width and interval of the wiring 48 in the FPC 150.

  Returning to FIG. 13, a common electrode 134 having the same outer shape as the piezoelectric sheet 141 and a thickness of about 2 μm is interposed between the uppermost piezoelectric sheet 141 and the lower piezoelectric sheet 142. Both the individual electrode 135 and the common electrode 134 are made of, for example, a metal material such as an Ag—Pd system. The common electrode 134 is grounded in a region not shown. As a result, the common electrode 134 is kept at an equal and constant potential in the region corresponding to all the pressure chambers 110, that is, the ground potential in the present embodiment.

  As shown in FIG. 13, the FPC 150 has substantially the same configuration as the FPC 50 described above, and only the arrangement form of terminals 146 electrically connected to the plurality of wirings 48 is different. Accordingly, the same components are denoted by the same reference numerals and description thereof is omitted. A plurality of terminals 146 of the FPC 150 are provided at positions facing the land portions 136 of the individual electrodes 135, and each terminal 146 is configured to be able to be joined to one land portion 136. Each terminal 146 has a wiring 48 drawn out in one direction (the width direction of the flow path unit 104 and the sub-scanning direction) toward the proximal end side and the distal end side of the FPC 150. Among these, each terminal 146 is independently connected to the driver IC 75 by the wiring 48 drawn to the base end side of the FPC 150. Thereby, the potential can be controlled for each pressure chamber 110. In the FPC 150 of the present embodiment, as in the FPC 50 described above, the wiring 48 extends from the terminal 146 to the base of the FPC 150 in order to perform solder plating on the terminal 146 of the FPC 150 by electrolytic plating. It is pulled out toward the end side and the front end side. Further, after each terminal 146 of the FPC 150 is subjected to solder plating, the front end side portion of the FPC 150 is cut leaving a portion facing the actuator unit 121 of the FPC 150 (a region where the plurality of terminals 146 of the FPC 150 are formed) The FPC 150 is configured as shown in FIG.

  Further, among the plurality of wirings 48 drawn from each terminal 146 of the FPC 150, the wirings 48 other than the wiring 48 drawn from the terminal 146 form a wiring non-formation region 139 while avoiding the peripheral region of the terminal 146. Is bent. Further, the wirings 48 drawn from the respective terminals 146 of the FPC 150 are arranged at almost equal intervals in a region sandwiched between the peripheral regions of the terminals 146.

  Next, a method for driving the actuator unit 121 will be described. Since the actuator unit 21 and the actuator unit 121 described above have substantially the same configuration, the driving method is also substantially the same. That is, the actuator unit 121 has a so-called unimorph type configuration in which the polarization direction of the piezoelectric sheet 141 is the thickness direction. Therefore, when the individual electrode 135 has a predetermined positive or negative potential with respect to the common electrode 134, for example, if the electric field and polarization are in the same direction, the electric field application portion sandwiched between the electrodes in the piezoelectric sheet 141 serves as an active portion. It shrinks in the direction perpendicular to the polarization direction due to the piezoelectric transverse effect.

  On the other hand, since the piezoelectric sheets 142 to 144 are not spontaneously displaced because they are not affected by the electric field, the piezoelectric sheets 142 to 144 are not displaced in the direction perpendicular to the polarization direction between the upper piezoelectric sheet 141 and the lower piezoelectric sheets 142 to 144. A difference is caused in the distortion, and the piezoelectric sheets 141 to 144 try to be deformed so as to be convex toward the non-active side (unimorph deformation). At this time, as shown in FIG. 13, the lower surface of the actuator unit 121 is fixed to the upper surface of the partition wall (cavity plate 122) that partitions the pressure chamber 110, and as a result, the piezoelectric sheets 141 to 144 are placed on the pressure chamber side. Deforms to become convex. As a result, the volume of the pressure chamber 110 decreases, the ink pressure increases, and ink is ejected from the nozzles 108. Thereafter, when the individual electrode 135 is returned to the same potential as that of the common electrode 134, the piezoelectric sheets 141 to 144 have the original shape and the volume of the pressure chamber 110 returns to the original volume, so that ink is sucked from the manifold channel 105 side. .

  As another driving method, the individual electrode 135 is set to a potential different from that of the common electrode 134 in advance, and the individual electrode 135 is once set to the same potential as the common electrode 134 every time there is an ejection request, and then again individually at a predetermined timing. The electrode 135 can have a potential different from that of the common electrode 134. In this case, when the individual electrodes 135 and the common electrode 134 are at the same potential, the piezoelectric sheets 141 to 144 return to their original shapes, so that the volume of the pressure chamber 110 is in an initial state (the potentials of the two electrodes are different). ) And the ink is sucked into the pressure chamber 110. Thereafter, at the timing when the individual electrode 135 is set to a potential different from that of the common electrode 134 again, the piezoelectric sheets 141 to 144 are deformed so as to protrude toward the pressure chamber 110, and the pressure to the ink increases due to the volume reduction of the pressure chamber 110. Ink is ejected. In this way, a desired image is printed on the paper on which ink is ejected from the nozzle 108 and conveyed.

  According to the ink jet head 100 as described above, the intervals between the plurality of wirings 48 drawn from the terminals 146 of the FPC 150 electrically connected to the plurality of individual electrodes 135 of the actuator unit 121 can be made relatively large. become. That is, as shown in FIG. 14, in the individual electrode row 137b of the actuator unit 121 closest to the proximal end side of the FPC 150, the auxiliary electrode region 135b is connected to the individual electrode 135 on the distal end side of the FPC 150 with respect to the main electrode region 135a. The individual electrode 135 in which the electrode region 135b exists in the base end side of FPC150 with respect to the main electrode region 135a exists alternately. Therefore, similarly to the inkjet head 1 described above, the intervals between the terminals 146 of the FPC 150 formed corresponding to the individual electrode 135 closest to the base end of the FPC 150 can be widened. That is, in the individual electrode row 137b, when considering the three individual electrodes 135 adjacent to each other, the auxiliary electrode region of the individual electrode 135 in which the auxiliary electrode region 135b is sandwiched between the two individual electrodes 135 on the base end side of the FPC 150. This is because the distance between the adjacent land portions 136 in the arrangement direction E becomes longer because 135b is on the front end side of the FPC 150. Accordingly, when the FPC 150 is manufactured, the interval between the terminals 146 of the FPC 150 is widened, and a space for drawing out the wiring 48 is created. Therefore, the FPC 150 is easily manufactured. Further, by increasing the size of the actuator unit, it is not necessary to widen the distance between the land portions 136 of the individual electrodes 135 and widen the distance between the wirings 48, and the size of the ink jet head can be prevented from being increased. In addition, since the individual electrodes 135 are arranged at positions facing the pressure chambers 110 arranged in a staggered pattern, the pressure chambers 110 and the individual electrodes 135 can be arranged with high density, and the image height can be increased. It can easily cope with resolution and high density of the pressure chamber.

  Further, in all the individual electrode rows 137 formed in the actuator unit 121 of the inkjet head 100, the auxiliary electrode region 135b has the individual electrode 135 on the front end side of the FPC 150 with respect to the main electrode region 135a, and the auxiliary electrode region 135b is the main electrode row. The individual electrodes 135 on the base end side of the FPC 150 are alternately present with respect to the electrode region 135 a, and the individual electrode 135 on the base end side of the FPC 150 is continuously arranged along the direction G. The individual electrode rows 138a and the individual electrode rows 138b in which the individual electrodes 135 having the auxiliary electrode region 135b on the front end side of the FPC 150 are continuously arranged along the direction G are provided two by two along the arrangement direction E. Since they are arranged alternately, they are connected to each of the terminals 146 formed corresponding to all the individual electrodes 135. The width and interval of the formed wirings 48 can be uniformly increased over the entire area. Therefore, the FPC 150 can be more easily manufactured regardless of high-density wiring. Furthermore, it is possible to easily cope with higher resolution and higher density, and it is possible to cope with the increase in the length of the inkjet head having the same effect. Further, the degree of freedom of the planar shape of the pressure chamber group 109 constituted by a plurality of pressure chambers 110 is increased. That is, regardless of the planar shape of the pressure chamber group formed by the plurality of pressure chambers 110 respectively facing the plurality of individual electrodes 135, the arrangement direction in any individual electrode row formed by the individual electrodes 135 If the auxiliary electrode regions 135b are alternately arranged along E, the interval between the land portions 136 of the auxiliary electrode region 135b increases, so that the interval between the terminals 146 of the FPC 150 also increases and the width of the wiring 48 drawn from the terminal 146 Spacing increases. Further, by arranging the pressure chambers 110 in a staggered manner in the arrangement direction E, a higher-density ink jet head is obtained. Furthermore, in the present embodiment, the wiring 48 is drawn out substantially orthogonal to the direction in which the individual electrode rows extend. This contributes to the fact that a larger number of wirings 48 can be provided without reducing the wiring width and the wiring interval even if the same land portion 136 has the same width.

  All the individual electrodes 135 in this embodiment are arranged in the regular arrangement form as described above for each actuator unit 121, but the band-like region R (that is, between the two two-dot chain lines shown in FIG. 12 (that is, In the adjacent region in the direction G of the actuator unit 121, the auxiliary electrode region 135 b of the individual electrode 135 may be formed so as to face the proximal end side or the distal end side of the corresponding FPC 150. That is, the auxiliary electrode regions 135b of the individual electrodes 135 existing in the belt-like region R all face the same direction and do not overlap each other in the width direction of the flow path unit 104. If they are alternately arranged along the arrangement direction E so as to face the side, the interval between the auxiliary electrode regions is widened and the interval between the terminals of the FPC 150 is also widened. Of the plurality of individual electrode rows 137 formed on the two adjacent actuator units 121, at least in the individual electrode row 137 closest to the proximal end side of each FPC 150, the individual electrode in which the auxiliary electrode region 135b is on the distal end side of the FPC 150, respectively. 135 and the individual electrode 135 on the base end side are mixed, the planar shape of each pressure chamber group 109 is restricted (that is, the pressure chamber groups 109 overlap each other in the width direction of the flow path unit 104). However, the above-described effects can be obtained.

  The preferred embodiments of the present invention have been described above. However, the present invention is not limited to the above-described embodiments, and various design changes can be made as long as they are described in the claims. For example, the inkjet heads 1 and 100 in the above-described embodiment are driven by a piezoelectric actuator unit, and ink is ejected from the nozzles. The ink in each pressure chamber is heated by a signal sent from the FPCs 50 and 150, The present invention is also applicable to an ink jet head that applies ejection energy to ink in a pressure chamber. In other words, the land electrodes 36 and 136 of the individual electrodes 35 and 135 connected to the terminals 46 and 146 of the FPCs 50 and 150 have the same configuration, a heating body is provided in each pressure chamber, and an individual electrode corresponding to each pressure chamber is provided. If the heating body is connected, the heating body can be heated by a signal from the FPC, and the invention can be applied to such an ink jet head.

  Further, the FPCs 50 and 150 are configured such that the wirings 48 are drawn from the terminals 46 and 146 to the proximal end side and the distal end side of the FPCs 50 and 150 for convenience in performing solder plating on the terminals 46 and 146. However, an FPC in which the wiring 48 is drawn out only on the base end side may be used. In this case, as the terminal position moves from the front end side to the base end side of the FPC, the number of wirings 48 drawn therefrom is gradually increased. That is, the density of the wiring 48 increases as it moves from the front end side to the base end side of the FPC. Therefore, at least in the region of the actuator unit on the base end side, by providing the regularity as shown in each embodiment to the auxiliary electrode region, the density can be increased even if the number of wirings 48 is increased. Each wiring 48 can be arranged.

1 is an external perspective view of an inkjet head according to an embodiment of the present invention. It is sectional drawing in the II-II line of FIG. FIG. 3 is a perspective view showing a state in which a reinforcing plate is bonded to the head body shown in FIG. 2. It is a top view of a head body. It is an enlarged view of the area | region enclosed with the dashed-dotted line drawn in FIG. It is sectional drawing in the VI-VI line of FIG. The actuator unit of the inkjet head by one Embodiment of this invention is shown, (a) is an enlarged view of the part enclosed with the dashed-dotted line in FIG. 6, (b) is a top view of an individual electrode. FIG. 8 is an enlarged view showing a region surrounded by a two-dot chain line shown in FIG. It is an external appearance perspective view of the inkjet head by other embodiment of this invention. It is sectional drawing along the XX line of FIG. It is a top view of the head main body with which FPC was joined. FIG. 12 is an enlarged plan view of a region surrounded by an alternate long and short dash line depicted in FIG. 11. It is sectional drawing along the XIII-XIII line | wire shown in FIG. It is an enlarged view which shows the area | region enclosed with the dashed-dotted line shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,100 Inkjet head 4,104 Flow path unit 4a, 103a Ink supply port 8,108 Nozzle 10,110 Pressure chamber 21,121 Actuator unit 35,135 Individual electrode 35a, 135a Main electrode area 35b, 135b Auxiliary electrode area 37 ( 37a, 37b, 37c, 37d), 137 (137a, 137b, 137c, 137d) Individual electrode row 138 (138a, 138b) Individual electrode row 46, 146 Terminal 48 Wiring 50, 150 FPC (flat flexible cable)

Claims (10)

A plurality of pressure chambers each communicating with the nozzle are arranged along a plane, and a flow path unit having an ink flow path from the ink supply port to the nozzle through the pressure chamber,
A plurality of individual electrodes each having a main electrode region formed corresponding to the pressure chamber and an auxiliary electrode region connected to the main electrode region, and fixed to the plane of the flow path unit, An actuator unit that applies ejection energy to the ink;
A flat flexible cable having a plurality of terminals each electrically connected to the auxiliary electrode region, and a plurality of wirings respectively connected to the plurality of terminals extending in one direction and drawn from the terminals; With
In the actuator unit, a plurality of individual electrode rows in which the individual electrodes are arranged along a direction intersecting the one direction are arranged in parallel to each other,
Among the plurality of individual electrode rows, in the individual electrode row that is farthest in the direction in which the wiring is drawn from at least the tip of the flat flexible cable, the auxiliary electrode region is more of the flat flexible cable than the main electrode region. The inkjet head, wherein the individual electrode on the distal end side and the individual electrode in the auxiliary electrode region on the proximal end side of the flat flexible cable with respect to the main electrode region are alternately arranged .   In all the individual electrode rows, the auxiliary electrode region is located on the distal end side of the flat flexible cable with respect to the main electrode region, and the flat flexible cable has the auxiliary electrode region with respect to the main electrode region. The inkjet head according to claim 1, wherein the individual electrodes on the base end side of the ink jet are mixed. In the actuator unit, a plurality of individual electrode rows belonging to every other individual electrode column are arranged so that a plurality of individual electrode rows arranged in parallel with the one direction are parallel to each other,
The inkjet head according to claim 2, wherein a plurality of the individual electrodes belonging to two adjacent individual electrode rows belong to different individual electrode columns.   In all the individual electrode rows, the auxiliary electrode region is located on the distal end side of the flat flexible cable with respect to the main electrode region, and the flat flexible cable has the auxiliary electrode region with respect to the main electrode region. The inkjet head according to claim 1, wherein the individual electrodes on the base end side of the inkjet head are alternately arranged. In the actuator unit, a plurality of individual electrode rows belonging to every other individual electrode column are arranged so that a plurality of individual electrode rows arranged in parallel with the one direction are parallel to each other,
The inkjet head according to claim 4 , wherein the plurality of individual electrodes belonging to two adjacent individual electrode rows belong to different individual electrode columns. The individual electrode row includes the individual electrode in which the auxiliary electrode region is on the distal end side of the flat flexible cable with respect to the main electrode region, and the auxiliary electrode region of the flat flexible cable with respect to the main electrode region. The inkjet head according to claim 5 , wherein there is a region where the individual electrodes on the base end side are alternately arranged. In the individual electrode row, a first individual electrode row having a region in which the plurality of individual electrodes are continuously arranged, the auxiliary electrode region being on the distal end side of the flat flexible cable with respect to the main electrode region, A second individual electrode row having a region in which the plurality of individual electrodes are continuously arranged, the auxiliary electrode region being closer to the base end side of the flat flexible cable than the main electrode region;
The inkjet head according to claim 5 , wherein the first individual electrode rows and the second individual electrode rows are alternately arranged two by two. The main electrode region is disposed at a position facing the pressure chamber;
A parallelogram shape planar shape of the pressure chamber has two acute angle portions, claim 1-7, characterized in that the intersecting direction is parallel to the diagonal line of the shorter of the pressure chamber 2. An ink jet head according to item 1. A plurality of pressure chambers each communicating with the nozzle are arranged along a plane, and a flow path unit having an ink flow path from the ink supply port to the nozzle through the pressure chamber,
An actuator unit that has a plurality of individual electrodes each having a main electrode region and an auxiliary electrode region connected to the main electrode region, and is fixed to the plane of the flow path unit to change the volume of the pressure chamber;
A plurality of terminals electrically connected to the auxiliary electrode region, and a flat flexible cable in which a plurality of wires respectively connected to the plurality of terminals extend in one direction;
In the flow path unit, a plurality of pressure chamber rows in which a plurality of the pressure chambers having a parallelogram-shaped planar shape having two acute angle portions are arranged in a direction crossing the one direction are parallel to each other. There are multiple arrays,
In the actuator unit, the individual electrodes arranged with the main electrode region facing the pressure chamber form a plurality of individual electrode rows parallel to each other, and the auxiliary electrode region is the main electrode region in all the individual electrode rows. The individual electrodes on the distal end side of the flat flexible cable with respect to the electrode region and the individual electrodes on which the auxiliary electrode region is located on the proximal end side of the flat flexible cable with respect to the main electrode region are alternately arranged. An ink jet head characterized by comprising: The inkjet head according to claim 9, wherein the intersecting direction is parallel to a shorter diagonal line of the pressure chamber.

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