JP4274084B2 - Inkjet head - Google Patents

Description

  The present invention relates to an ink jet head having nozzle holes for ejecting ink.

  An ink jet head distributes ink supplied from an ink tank to a plurality of pressure chambers via a common ink chamber in an ink jet printer or the like, and selectively applies a pulsed pressure to each pressure chamber. Ink is ejected from nozzles communicating with the chamber. As one means for selectively applying pressure to the pressure chamber, an actuator in which a plurality of piezoelectric sheets made of piezoelectric ceramic are laminated may be used. When the actuator is driven, pressure is generated in the pressure chamber corresponding to the actuator. Ink in the pressure chamber is ejected from the nozzle by the pressure generated in the pressure chamber. At this time, part of the pressure generated in the pressure chamber propagates to the common ink chamber. The pressure propagated to the common ink chamber may further propagate to other pressure chambers communicating with the common ink chamber and disturb the ink ejection characteristics from the nozzle communicating therewith.

  Therefore, a technique is known that includes a damper chamber formed adjacent to a common ink chamber (ink storage chamber) in an inkjet head (see Patent Document 1). According to this, since the pressure propagated from the pressure chamber to the common ink chamber is attenuated by the damper chamber, it is difficult for unnecessary pressure to propagate to other pressure chambers.

JP 2002-036539 A (FIG. 2)

  In the above-described technique, the larger the facing area between the damper chamber and the common ink chamber, the more efficiently the pressure propagated into the common ink chamber can be attenuated. However, in inkjet printers, due to the demand for high-speed printing and improved image quality, the size of the inkjet head and the density of nozzles and pressure chambers are increasing, so there is sufficient space between the damper chamber and the common ink chamber. It has become difficult to ensure.

  A main object of the present invention is to provide an ink jet head capable of increasing the facing area between a damper chamber and a common ink chamber.

Means for Solving the Problems and Effects of the Invention

An inkjet head according to the present invention is a laminated structure in which a plurality of sheet materials are laminated, one end of which is communicated with a nozzle and a plurality of pressure chambers formed along a plane, and communicated with the plurality of pressure chambers. A common ink chamber extending in one direction parallel to the plane, a first thin film portion constituting at least a part of a first inner wall surface parallel to the plane in the common ink chamber, A flow path unit including a first damper chamber adjacent to the common ink chamber via a first thin film portion, and a plurality of communication passages communicating with the other end of the pressure chamber and the common ink chamber And a plurality of actuators that impart ejection energy to the ink in the corresponding pressure chamber. The common ink chamber protrudes outward from the second inner wall surface intersecting the first inner wall surface , and includes a plurality of protruding portions arranged in a staggered manner along the one direction. Have. Further, the plurality of pressure chambers are arranged in a staggered matrix along the one direction to form a plurality of pressure chamber rows, and the pressure chamber rows are arranged in the common ink chamber with respect to the stacking direction of the sheet material. Is facing .

According to the present invention, since the common ink chamber and the pressure chamber communicate with each other through the communication path at the protruding portion protruding outward, the facing area between the first damper chamber and the common ink chamber can be increased. Thus, unnecessary pressure generated in the common ink chamber can be efficiently attenuated in the first damper chamber. Furthermore, since the plurality of pressure chambers are arranged in a staggered matrix along one direction, the pressure chambers and nozzles can be efficiently arranged.

  In the present invention, the second inner wall surface forms an intersection line shared with the first inner wall surface, and the protruding portion is formed on the first inner wall surface of the second inner wall surface. It is preferable to protrude outward from the continuous region. According to this, since the air staying in the common ink chamber is easily moved to the protrusion, the staying air can be efficiently discharged through the pressure chamber and the nozzle.

Furthermore, in the present invention, the common ink chamber is a first sheet material having the first inner wall surface and a second sheet that is adjacent to the first sheet material and forms a part of the second inner wall surface. of the sheet material a plurality of sheet material added is constituted by laminating, it is preferable that the protruding portion is formed on at least the second sheet material. According to this, the rigidity of the flow path unit is not impaired. Further, the projecting portion can be formed with a simple configuration.

In another aspect, the inkjet head of the present invention is a laminated structure in which a plurality of sheet materials are laminated, and has a plurality of pressure chambers, one end communicating with a nozzle and formed along a plane, a plurality of pressure chambers. A common ink chamber that communicates with the pressure chamber and extends in one direction parallel to the plane, and a first that forms at least a part of a first inner wall surface parallel to the plane in the common ink chamber. A first damper chamber adjacent to the common ink chamber via the first thin film portion, and a plurality of communication passages communicating with the other end of the pressure chamber and the common ink chamber. And a plurality of actuators for applying ejection energy to the ink in the corresponding pressure chamber. The common ink chamber protrudes outward from the second inner wall surface intersecting with the first inner wall surface, and a plurality of protruding portions arranged in a staggered manner along the one direction. Have. Furthermore, one end of the communication passage communicates with the common ink chamber at the protruding portion. In addition, the projecting portion is formed from the end portion on the first inner wall surface side to the opposite end portion of the second inner wall surface, and the plurality of pressure chambers are arranged in the one direction. A plurality of pressure chamber rows are formed in a staggered matrix along the plurality of pressure chamber rows, and the pressure chamber rows face the common ink chamber in the stacking direction of the sheet material .

According to the present invention, since the common ink chamber and the pressure chamber communicate with each other through the communication path at the protruding portion protruding outward, the facing area between the first damper chamber and the common ink chamber can be increased. Thus, unnecessary pressure generated in the common ink chamber can be efficiently attenuated in the first damper chamber. Further, since the volume of the common ink chamber can be increased, ink in the common ink chamber can be efficiently flowed. Furthermore, since the plurality of pressure chambers are arranged in a staggered matrix along one direction, the pressure chambers and nozzles can be efficiently arranged.

  In the present invention, it is preferable that a cross section of the common ink chamber orthogonal to the one direction has a rectangular shape. According to this, since the common ink chamber can be easily formed, the manufacturing cost of the inkjet head can be reduced.

  Moreover, in this invention, it is preferable that the communicating port in the boundary of the said protrusion part and the said communicating path is parallel to the said plane. According to this, the air staying in the common ink chamber can be discharged more efficiently through the pressure chamber and the nozzle.

  Furthermore, in the present invention, it is preferable that the inner wall surface of the protruding portion is curved so as to draw an arc in a plan view of the common ink chamber. According to this, the flow of ink in the protrusion can be made smooth.

In addition, in the present invention, the flow path unit has a third inner wall surface facing the first inner wall surface in the common ink chamber, and at least a part of the third inner wall surface is formed. It is preferable to further include a second thin film portion to be configured and a second damper chamber adjacent to the common ink chamber via the second thin film portion. According to this, unnecessary pressure generated in the common ink chamber can be attenuated more efficiently. In the present invention, the communication path may be communicated so that the inner wall surfaces thereof coincide with each other at a position farthest from the common ink chamber in the protruding portion, and the other end of the pressure chamber may be , Communicating with one end of a throttle constituting the communication channel, the throttle facing the other pressure chamber adjacent thereto, and parallel to the plane at different positions with respect to the pressure chamber and the stacking direction. It may extend to. Further, the pressure chamber communicates with the protruding portion protruding from one inner wall surface in the width direction of the common ink chamber through the diaphragm, and is disposed outside the other inner wall surface. It may communicate with the nozzle. The inkjet head may be a line type.

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

<First Embodiment>
FIG. 1 is an external perspective view of the ink jet head according to the first 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 main 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. And a flexible printed circuit board (FPC) 50 that is a signal transmission board attached to the head body 70.

  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. . These four ink chambers 3 are respectively connected to corresponding ink cartridges (not shown) by tubes 40 (see FIG. 1), and ink of each color is supplied from the ink cartridges to the ink chambers 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 has an opening 42 having a rectangular planar shape, and an actuator unit (piezoelectric actuator) 21 to be described later is disposed in the opening 42. Thus, the head main body 70 is bonded and fixed. 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. Further, the FPC 50 is fixed to the upper surface of the actuator unit 21 by a thermosetting adhesive 56 (see FIG. 8), pulled out to one side in the main scanning direction, and pulled upward while being bent. Further, a protective plate 44 for protecting the FPC 50 and the actuator unit 21 is attached to the upper surface of the FPC 50. The protective plate 44 functions to make the temperature distribution generated in the actuator unit 21 uniform and to align the ink ejection characteristics.

  The FPC 50 fixed 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. The FPC 50 is electrically connected 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 one direction (sub-scanning direction) of the flow path unit 4. 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 side. Furthermore, as will be described later, each of the manifold channels 5M, 5Y, 5C, and 5K is branched into two sub-manifolds 5a (see FIG. 5). 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 supplied from the ink tank 71 into the flow path unit 4 is captured by the filter 45a 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) and gaps 60 (see FIG. 5) 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 and the gaps 60.

  FIG. 5 is an enlarged view of a region surrounded by a one-dot chain line drawn in FIG. In the flow path unit 4, 16 pressure chamber rows 11 in which a plurality of pressure chambers 10 are arranged in parallel with the manifold flow passage 5 (sub-manifold 5 a), and a large number of gaps 60 are arranged in parallel with the pressure chamber rows 11. The four gap rows 61 thus formed are formed. The 16 pressure chamber rows 11 are divided into 12 groups and 4 groups by a group of four gap rows 61 formed adjacent to each other. As shown in FIG. 5, the pressure chamber 10 and the gap 60 have the same planar shape and size. The large number of pressure chambers 10 and the gaps 60 are regularly arranged so that one arrangement pattern is formed in the flow path unit 4 when the two are considered to be indistinguishable.

  The manifold channels 5M, 5Y, 5C, and 5K are branched into two sub-manifolds 5a extending in parallel with the pressure chamber row 11, respectively. The sub-manifold 5a protrudes outward from both inner wall surfaces 5b and 5c in the width direction in plan view, and includes a large number of protrusions 80 arranged in a staggered manner along the extending direction. As will be described later, each protrusion 80 corresponds to one pressure chamber 10, and the protrusion 80 and the pressure chamber 10 communicate with each other via the aperture 13 and the communication hole 68. Further, in the plan view of the flow path unit 4, the inner wall surface of the protrusion 80 is curved so as to draw an arc. In the present embodiment, as shown in FIG. 6, the communication hole 68 and the protruding portion 80 are disposed so that their inner wall surfaces coincide with each other at the position farthest from the sub-manifold 5 a. In addition, since the protruding portion 80 has a curved inner wall surface, for example, even if bubbles may flow into the sub-manifold 5a, It is easily discharged to the outside through the communication hole 68.

  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 One end of each pressure chamber 10 communicates with the nozzle 8, and the other end communicates with the sub-manifold 5 a via the aperture 13. Thereby, a large number of individual ink flow paths 7 (see FIG. 6) connected to the nozzles 8 and formed for each pressure chamber 10 are connected to each sub-manifold 5 a. In FIG. 5, the pressure chamber 10, the gap 60, 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 7, and is a cross-sectional view taken along line VI-VI shown in FIG. FIG. 7 is a cross-sectional view taken along the line VII-VII shown in FIG. 6 in the extending direction of the sub-manifold 5a. As can be seen from FIG. 6, each nozzle 8 communicates with the sub-manifold 5 a via the pressure chamber 10, the aperture (that is, the throttle) 13 and the communication hole 68 (the communication path is constituted by the aperture 13 and the communication hole 68). . The sub-manifold 5a has a rectangular cross-sectional shape and a protrusion 80. That is, the sub-manifold 5a intersects the inner wall surface 5b with a pair of inner wall surfaces (first inner wall surface) 5b disposed in parallel to the bonding surface (plane) 4b between the flow path unit 4 and the actuator unit 21. And a pair of inner wall surfaces (second inner wall surfaces) 5c. In the present embodiment, the inner wall surface 5 c is disposed along the thickness direction of the flow path unit 4. Further, the protruding portion 80 protrudes outward from an area of the inner wall surface 5c that is continuous with the inner wall surface 5b. Therefore, the protrusion 80 is formed so as to protrude substantially horizontally from the uppermost side wall (inner wall surface 5c) in the gravity direction in the sub-manifold 5a. The protrusion 80 communicates with the communication hole 68 via a communication port 69 formed on the actuator unit 21 side. The communication hole 68 further communicates with the aperture 13. The communication port 69 is formed so as to be parallel to the bonding surface 4 b of the flow path unit 4. One flow path is formed from the communication port 69 of the protrusion 80 of the sub-manifold 5a to the nozzle 8 through the communication hole 68, the aperture 13, and the pressure chamber 10. In this way, the individual ink channels 7 are formed in the head body 70 for each pressure chamber 10.

  Further, an upper damper chamber (first damper chamber) 81 is formed so as to be adjacent to the sub manifold 5a via an upper thin film portion (first thin film portion) 81a constituting a part of the inner wall surface 5b of the sub manifold 5a. Has been. As shown in FIG. 7, the upper damper chamber 81 extends in one direction along the sub-manifold 5a. Further, communication holes 68 are arranged in a staggered manner on both sides in the width direction of the upper damper chamber 81. In the present embodiment, in order to prevent the upper damper chamber 81 formed by the upper thin film portion 81a and the communication hole 68 from communicating with each other, it is necessary for both questions to pass through a predetermined gap. For this reason, a part of the communication hole 68 protrudes so as to narrow the width of the upper thin film portion 81a. Accordingly, the upper damper chamber 81 is narrowed. Of course, although it is a balance with the required arrangement density of the individual ink flow paths 7, from the viewpoint of obtaining a larger damper effect, the upper damper chamber 81 has an area approximately the same as the plan view of the sub-manifold 5a. It is effective. In this case, for example, the protrusion amount of the protrusion 80 may be made larger than that in the present embodiment. Further, a lower damper chamber (a second manifold chamber a) is adjacent to the sub-manifold 5a via a lower thin film portion (second thin film portion) 82a constituting a part of an inner wall surface (third inner wall surface) facing the upper thin film portion 81a. A second damper chamber 82 is formed. Similarly to the upper damper chamber 81, the lower damper chamber 82 extends in one direction along the sub-manifold 5a. Further, the lower damper chamber 82 has a shape similar to that of the sub-manifold 5a in a plan view and is formed in substantially the same area. Therefore, the upper damper chamber 81 and the lower damper chamber 82 are disposed so as to face each other with the sub-manifold 5a interposed therebetween.

  As shown in FIG. 6, the head main body 70 includes, from above, the actuator unit 21, the cavity plate 22, the base plate 23, the aperture plate 24, the supply plate 25, the upper damper plate (first plate) 66, the manifold plate (second plate). Plate) 26, 27 to 29, lower damper plate 67, and nozzle plate 30, a total of 12 sheet materials are laminated. Among these, the flow path unit 4 is composed of 11 plates excluding the actuator unit 21.

  The actuator unit 21 is a laminate of four piezoelectric sheets 31 to 34 (see FIG. 8), as will be described in detail later. Of these, only the uppermost layer is a layer having a portion that becomes an active portion when an electric field is applied (hereinafter simply referred to as “a layer having an active portion”), and the remaining three layers are an inactive layer having no active portion. It has been done. The cavity plate 22 is a metal plate in which a large number of diamond-shaped holes constituting the pressure chamber 10 and the gap 60 are provided in the pasting range (adhesion region) 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 hole which becomes a part of the communication hole 68 communicating with 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 upper damper plate 66 is a hole that becomes a part of the communication hole 68 that communicates with the aperture 13 for one pressure chamber 10 of the cavity plate 22, a communication hole from the pressure chamber 10 to the nozzle 8, and one of the upper damper chamber 81. It is the metal plate in which the recessed part used as a part was provided, respectively. That is, the communication hole 68 is formed by the holes of the supply plate 25 and the upper damper plate 66. In addition, the bottom of the concave portion that becomes a part of the upper damper chamber 81 becomes the upper thin film portion 81a.

  The manifold plates 26 to 29 are metal plates provided with a hole that is a part of the sub-manifold 5 a and a communication hole from the pressure chamber 10 to the nozzle 8 for one pressure chamber 10 of the cavity plate 22. Note that a hole that becomes a part of the sub-manifold 5 a of the manifold plate 26 includes a portion that becomes the protruding portion 80. 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. The lower damper plate 67 is a metal plate provided with a recess that is a part of the lower damper chamber 82. The bottom of the recess that becomes the lower damper chamber 82 becomes the lower thin film portion 82a.

  These twelve sheets 21 to 30, 66, and 67 are stacked 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 extends upward from the sub-manifold 5 a through the communication hole 68, extends horizontally at the aperture 13, then further upwards, extends horizontally again at the pressure chamber 10, and then for a while. From the diagonally downward direction away from the aperture 13 toward the nozzle 8 vertically downward.

  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. Accordingly, as shown in FIG. 5, the aperture 13 communicating with one pressure chamber 10 is arranged at the same position in plan view as another pressure chamber 10 adjacent to the pressure chamber, as shown in FIG. 5. Is possible. 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 pressure chamber 10 communicates with the nozzle 8 at one end of the long diagonal line, and communicates with the sub-manifold 5 a via 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. 8) whose planar shape is substantially rhombus and slightly smaller than the pressure chamber 10 are arranged in a matrix so as to face the pressure chamber 10. Yes. FIG. 5 shows only one of the plurality of individual electrodes 35 in order to simplify the drawing.

  The plurality of gaps 60 formed in the cavity plate 22 are defined by 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. ing. Therefore, no ink flow path is connected to the gap 60, and the plurality of gaps 60 are not filled with ink. The plurality of gaps 60 are adjacently arranged in a matrix in a staggered arrangement pattern in two directions of the arrangement direction A (sub-scanning direction) and the arrangement direction B. The plurality of gaps 60 form four gap rows 61 parallel to each other, and the four gap rows 61 constitute a gap group 62. A plurality of pressure chambers 10 are formed in the flow path unit 4 so as to sandwich the gap group 62.

  In the present embodiment, both the pressure chamber 10 and the gap 60 are formed regardless of their shape, size, and arrangement. As a whole, the pressure chambers 10 and the gaps 60 are adjacently arranged in a matrix in a staggered arrangement pattern in two directions of the arrangement direction A and the arrangement direction B. 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.

  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), 11a → 11c → 11b → 11d → 11a → 11c → 11b. 4 pieces are periodically arranged in the order of 11d →. 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 each pressure chamber group 12, the projections in the scanning direction of the nozzles 8 corresponding thereto do not overlap each other. For example, in the present embodiment, the nozzle 8 is capable of printing with a resolution of 150 dpi, so that the projection in the scanning direction of the nozzle 8 in each pressure chamber group 12 is separated by a distance corresponding to 37.5 dpi.

  The pressure chamber 10a constituting the pressure chamber row 11a and the pressure chamber 10c constituting the pressure chamber row 11c communicate with the same sub-manifold 5a. Further, the pressure chamber 10b constituting the pressure chamber row 11b and the pressure chamber 10d constituting the pressure chamber row 11d communicate with the same sub-manifold 5a. Each pressure chamber 10 communicates with a projecting portion 80 projecting from one inner wall surface 5c in the width direction of the sub-manifold 5a through the aperture 13 and the communication hole 68, and outside the other inner wall surface 5c. It communicates with the nozzle 8 arranged in the. Moreover, the nozzle 8 is arrange | positioned between protrusion part 80 of the other submanifold 5a in planar view.

  Next, the configuration of the actuator unit 21 and the FPC 50 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.

  8A and 8B show an actuator unit, in which FIG. 8A is an enlarged view of a portion surrounded by a one-dot chain line in FIG. 6, and FIG. 8B is a plan view of an individual electrode. In FIG. 8, in order to make the drawing easier to understand, the terminal portion 48a, the wiring 48b, and the like that are in the FPC 50 and should be drawn with broken lines are drawn with solid lines. As shown in FIGS. 8A and 8B, the individual electrode 35 is disposed at a position facing the pressure chamber 10, and a main electrode region 35 a formed in the planar region of the pressure chamber 10 in a 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. 8A, the actuator unit 21 includes four piezoelectric sheets 31 to 34 each having a thickness of about 15 μm. The piezoelectric sheets 31 to 34 are formed into a continuous layered flat plate (continuous flat plate layer) so as to be disposed across a large number of pressure chambers 10 and gaps 60 formed in the ink discharge region in the head main body 70. Yes. The piezoelectric sheets 31 to 34 are made of a lead zirconate titanate (PZT) ceramic material having ferroelectricity.

  As shown in FIG. 8B, the main electrode region 35a of the individual electrode 35 formed on the uppermost piezoelectric sheet 31 has a substantially rhombic planar shape that is substantially similar to the pressure chamber 10. A sharp corner portion on the left side in FIG. 8B in the substantially rhomboid main electrode region 35a extends to a region overlapping with the sharp corner portion of the pressure chamber 10, 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. The land portion 36 is a terminal that is electrically connected to a terminal portion 48a that becomes a joint portion described later. As shown in FIG. 8B, the land portion 36 is opposed to a region of the cavity plate 22 where the pressure chamber 10 is not formed, and has a diameter of about 0.3 mm and a thickness of about 10 μm. Yes. 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.

  A common electrode 37 having the same outer shape as the piezoelectric sheet 31 and a thickness of about 2 μm is interposed between the uppermost piezoelectric sheet 31 and the lower piezoelectric sheet 32. Both the individual electrode 35 and the common electrode 37 are made of, for example, a metal material such as Ag—Pd.

  The common electrode 37 is grounded in a region not shown. Thereby, the common electrode 37 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. 8A, the FPC 50 includes a base film (flexible layer) 46 and a conductor pattern 47 formed on the lower surface of the base film 46 (a surface facing the head body 70). The base film 46 is made of a polyimide resin film having flexibility and insulation. The conductor pattern 47 is made of copper foil.

  The conductor pattern 47 includes a plurality of terminal portions 48a formed at positions facing the land portions 36 of the base film 46, and wirings 48b drawn from the center of the lower ends of the terminal portions 48a toward the base end side of the FPC 50. Have. The terminal portion 48a is formed in a circular planar shape. The surface of the terminal portion 48a is plated with gold (not shown) in order to prevent oxidation of the terminal portion 48a and ensure reliable conduction to the land portion 36.

  The plurality of wirings 48 b are respectively connected to the driver IC 75 on the base end side of the FPC 50. In the base film 46, a part of the region facing the land portion 36 is formed with a convex portion 51 that protrudes toward the center of the land portion 36. A protruding portion 55 that protrudes from the central portion of the terminal portion 48 a toward the center of the land portion 36 is formed on the terminal portion 48 a so as to face the convex portion 51.

  An epoxy-based thermosetting adhesive 56 made of a non-conductive material is disposed around the protrusion 55, and the tip of the protrusion 55 is caused by the contraction force accompanying the curing of the thermosetting adhesive 56. The surface of the land 36 is crushed in contact with the surface. As a result, the terminal portion 48a and the land portion 36 are electrically connected. With such a configuration, the FPC 50 can transmit a drive signal from the driver IC 75 to the individual electrode 35 via the wiring 48b and the terminal portion 48a. That is, each of the plurality of individual electrodes 35 is connected to the driver IC 75 via the independent terminal portion 48 a and the wiring 48 b in the FPC 50. This makes it possible to control ink ejection for each pressure chamber 10.

  Next, a method for driving the actuator unit 21 will be described. The polarization direction of the piezoelectric sheet 31 in the actuator unit 21 is the thickness direction thereof. In other words, the actuator unit 21 includes the upper piezoelectric sheet 31 (that is, away from the pressure chamber 10) as the active portion layer and the lower piezoelectric element 10 (that is, close to the pressure chamber 10). It has a so-called unimorph type structure in which 32 to 34 are inactive layers. Accordingly, when the individual electrode 35 is set to a predetermined potential that is positive or negative with respect to the ground 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 31 functions as an active 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 37 in the piezoelectric sheet 31 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 32 to 34 below the piezoelectric sheet 31 are not applied with an electric field from the outside, and therefore hardly function as active parts. Therefore, a portion of the piezoelectric sheet 31 sandwiched mainly between the main electrode region 35a and the common electrode 37 contracts in a direction perpendicular to the polarization direction due to the piezoelectric lateral effect.

  On the other hand, the piezoelectric sheets 32 to 34 are not spontaneously displaced because they are not affected by the electric field, so that the piezoelectric sheets 32 to 34 are not displaced in the direction perpendicular to the polarization direction between the upper piezoelectric sheet 31 and the lower piezoelectric sheets 32 to 34. A difference is caused in the distortion, and the whole piezoelectric sheets 31 to 34 try to be deformed so as to protrude toward the non-active side (unimorph deformation). At this time, as shown in FIG. 8A, the lower surface of the actuator unit 21 constituted by the piezoelectric sheets 31 to 34 is fixed to the upper surface of the partition wall (cavity plate) 22 that partitions the pressure chamber. Specifically, the piezoelectric sheets 31 to 34 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 37, the piezoelectric sheets 31 to 34 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 37 in advance, and the individual electrode 35 is temporarily set to the same potential as the common electrode 37 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 37. In this case, when the individual electrode 35 and the common electrode 37 become the same potential, the piezoelectric sheets 31 to 34 return to the original shape, so that the volume of the pressure chamber 10 is in an initial state (a state where 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 37 again, the piezoelectric sheets 31 to 34 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 first embodiment described above, the sub-manifold 5a and the pressure chamber 10 communicate with each other at the projecting portion 80 projecting toward the outside of the sub-manifold 5a, so that the upper damper chamber 81 faces the sub-manifold 5a. The area to be performed can be enlarged. Thereby, unnecessary pressure generated in the sub-manifold 5a can be efficiently attenuated in the upper damper chamber 81.

  Further, since the protruding portion 80 protrudes outward from the region of the inner wall surface 5c of the sub-manifold 5a that is continuous with the inner wall surface 5b, the air staying in the sub-manifold 5a easily moves to the protruding portion 80. . Thereby, the staying air can be efficiently discharged through the pressure chamber 10 and the nozzle 8.

  Furthermore, since the hole of the manifold plate 26 forms the protrusion 80, the rigidity of the flow path unit 4 is not impaired. Further, the protruding portion 80 can be formed with a simple configuration.

  In addition, since the protrusions 80 are arranged in a staggered manner along the extending direction of the sub-manifold 5a, the pressure chambers and nozzles can be efficiently arranged. Further, the area facing the sub manifold 5a in the upper damper chamber 81 can be made larger.

  In addition, since the sub-manifold 5a has a rectangular cross section, the sub-manifold 5a can be easily formed. Thereby, the manufacturing cost of the inkjet head 1 can be reduced.

  Furthermore, since the communication port 69 is formed so as to be parallel to the bonding surface 4 b of the flow path unit 4 with the actuator unit 21, the air staying in the sub manifold 5 a is more passed through the pressure chamber 10 and the nozzle 8. It can be discharged efficiently.

  In addition, since the inner wall surface of the protrusion 80 is curved so as to draw an arc in the plan view of the flow path unit 4, the ink flow in the protrusion 80 can be made smooth.

  Further, since the flow path unit 4 includes the second damper chamber, it is possible to attenuate the unnecessary pressure generated in the sub manifold 5a even more efficiently.

<Second Embodiment>
Next, an ink jet head according to a second embodiment of the present invention will be described with reference to FIG. The same members as those of the ink jet head 1 of the first embodiment are denoted by the same reference numerals as those of the first embodiment, and the description thereof is omitted. FIG. 9 is a cross-sectional view showing individual ink flow paths in the flow path unit 104 of the head main body 170 provided in the ink jet head according to the second embodiment (cross section taken along line VI-VI shown in FIG. 5). Equivalent to the figure).

  As can be seen from FIG. 9, each nozzle 8 communicates with the sub-manifold 105 a via the pressure chamber 10, the aperture 13, and the communication hole 68 (a communication path is constituted by the aperture 13 and the communication hole 68). The sub-manifold 105a has a rectangular cross-sectional shape and a protrusion 180. That is, the sub-manifold 105a intersects the inner wall surface 105b with a pair of inner wall surfaces (first inner wall surface) 105b disposed in parallel to the bonding surface (plane) 104b between the flow path unit 104 and the actuator unit 21. And a pair of inner wall surfaces (second inner wall surfaces) 105c. In the present embodiment, in the inner wall surface 105c, the protruding portion 180 protrudes outward from a region continuous with the inner wall surface 105b of the inner wall surface 5c, but is opposite to the end on the actuator unit 21 side. It is characterized in that it protrudes across the end. The protrusion 180 communicates with the communication hole 68 through a communication port 69 formed on the actuator unit 21 side. The communication port 69 is formed so as to be parallel to the plane of the flow path unit 104. One flow path is formed from the communication port 69 of the projecting portion 180 of the sub-manifold 105 a to the nozzle 8 through the communication hole 68, the aperture 13, and the pressure chamber 10. In this way, the individual ink channels 7 are formed in the head body 170 for each pressure chamber 10.

  The head body 170 includes, from above, the actuator unit 21, the cavity plate 22, the base plate 23, the aperture plate 24, the supply plate 25, the upper damper plate (first plate) 66, the manifold plate (second plate) 26, 127 to 129, the lower damper plate 67, and the nozzle plate 30 have a laminated structure in which a total of 12 sheet materials are laminated. Among these, the flow path unit 4 is composed of 11 plates excluding the actuator unit 21.

  Since the actuator unit 21, the cavity plate 22, the base plate 23, the aperture plate 24, the supply plate 25, the upper damper plate 66, the lower damper plate 67, and the nozzle plate 30 are the same as those in the first embodiment, a detailed description will be given. Omitted.

  The manifold plates 26 and 127 to 129 communicate from the pressure chamber 10 to the nozzle 8 with respect to a hole that becomes a part of the sub-manifold 5 a including a portion that becomes the protruding portion 180 and one pressure chamber 10 of the cavity plate 22. It is a metal plate provided with holes.

  These twelve sheets 21 to 30, 66, and 67 are stacked 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 directed upward from the sub-manifold 105a through the communication hole 68, extends horizontally at the aperture 13, then further upwards, extends horizontally again at the pressure chamber 10, and then for a while. From the diagonally downward direction away from the aperture 13 toward the nozzle 8 vertically downward.

  According to the second embodiment described above, the sub-manifold 5a and the pressure chamber 10 communicate with each other in the protruding portion 180, so that the region facing the sub-manifold 105a in the upper damper chamber 81 can be enlarged with a simple configuration. it can. Further, since the volume in the sub-manifold 105a can be increased, the ink in the sub-manifold 105a can flow more efficiently.

  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, in the first and second embodiments described above, the protrusions 80 and 180 are directed toward the outside of the region of the inner wall surfaces 5c and 105c of the sub-manifolds 5a and 105a that are continuous with the inner wall surfaces 5b and 105b. Although it is the structure which protrudes, it is not limited to such a structure, The structure which a protrusion part protrudes from the arbitrary positions of the inner wall surface along the thickness direction of the flow-path unit of a submanifold may be sufficient.

  Moreover, in 1st Embodiment mentioned above, although it is the structure by which the some protrusion part 80 is arrange | positioned in zigzag form in planar view, a protrusion part is arrange | positioned so that it may protrude in arbitrary positions. Also good. For example, you may arrange | position so that a some protrusion part may mutually oppose. Moreover, the number of protrusions may be one. When the number of protrusions is one, the protrusions are formed long along the extending direction of the sub-manifold, whereby the capacity of the sub-manifold can be increased and the flow of ink can be made smooth.

  Furthermore, in the first and second embodiments described above, the sub-manifolds 5a and 105a have a rectangular cross section, but the sub-manifolds 5a and 105a may have any arbitrary cross-sectional shape such as a trapezoid or a hexagon. It may be.

  In addition, in the first and second embodiments described above, the communication port 69 is configured to be parallel to the bonding surfaces 4b and 104b of the flow path units 4 and 104 with the actuator unit 21. It may be configured in any orientation. For example, you may be comprised so that it may become perpendicular | vertical with respect to the adhesion surface with the actuator unit in a flow-path unit.

  In the first and second embodiments described above, the inner wall surfaces of the projecting portions 80 and 180 are curved. However, the inner wall surfaces of the projecting portions may not be curved.

  Furthermore, in the first and second embodiments described above, the lower damper chamber 82 is provided, but the lower damper chamber 82 may not be provided.

  In the first and second embodiments described above, the four-color inkjet head 1 has been described. However, different types of ink may be supplied to each sub-manifold to form an eight-color inkjet head. The same type of ink may be supplied to all the sub-manifolds to form a monochrome ink jet head.

  Furthermore, in the first and second embodiments described above, four manifold channels serving as common ink chambers are formed, but more manifold channels may be provided. In addition, each manifold flow path is branched into two sub-manifolds, but may not be branched into sub-manifolds, or may be branched into three or more sub-manifolds.

The ink jet head in the first and second embodiments described above, but is intended to be applied to a serial type ink jet printer, it is also applicable to an ink jet head applied to the line type inkjet Topu printer. The ink jet head is driven by a piezoelectric actuator unit, and ink is ejected from the nozzle. The ink in each pressure chamber is heated by a signal sent from the FPC to give ejection energy to the ink in the pressure chamber. Even an inkjet head of this type can be applied.

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. FIG. 3 is a plan view of the head main body shown in FIG. 2. It is an enlarged view of the area | region enclosed with the dashed-dotted line drawn in FIG. It is sectional drawing along the VI-VI line of FIG. It is sectional drawing along the VII-VII line of FIG. The actuator unit of FIG. 6 is shown, (a) is an enlarged view of a portion surrounded by a one-dot chain line in FIG. 6, and (b) is a plan view of an individual electrode. It is sectional drawing which shows the individual ink flow path in the flow path unit of the head main body with which the inkjet head which is 2nd Embodiment is provided.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Inkjet head 4 Flow path unit 4b Bonding surface 5 Manifold flow path 5a Sub manifold 5b, 5c Inner wall surface 13 Aperture 21 Actuator unit 31-34 Piezoelectric sheet 35 Individual electrode 36 Land part 37 Common electrode 50 FPC
69 Communication port 80 Projection 81 Upper damper chamber 81a Upper thin film portion 82 Lower damper chamber 82a Lower thin film portion

Claims (12)

A laminated structure in which a plurality of sheet materials are laminated, one end communicating with a nozzle and a plurality of pressure chambers formed along a plane, communicating with the plurality of pressure chambers and on the plane A common ink chamber extending in one parallel direction, a first thin film portion constituting at least a part of a first inner wall surface parallel to the plane in the common ink chamber, and the first thin film portion. A flow path unit including a first damper chamber adjacent to the common ink chamber, and a plurality of communication passages communicating with the other end of the pressure chamber and the common ink chamber;
A plurality of actuators each for imparting ejection energy to the corresponding ink in the pressure chamber;
The common ink chamber protrudes outward from a second inner wall surface intersecting the first inner wall surface , and has a plurality of protrusions arranged in a staggered manner along the one direction. And
The plurality of pressure chambers are arranged in a staggered matrix along the one direction to form a plurality of pressure chamber rows,
The inkjet head , wherein the pressure chamber row is opposed to the common ink chamber in the sheet material stacking direction . The second inner wall surface forms an intersection line shared with the first inner wall surface;
2. The inkjet head according to claim 1, wherein the protruding portion protrudes outward from a region of the second inner wall surface continuous with the first inner wall surface. A plurality of said common ink chamber, plus a second sheet member that constitutes a part of the first sheet material and the first adjacent sheet said second inner wall surface having a first inner wall surface The sheet material of
The inkjet head according to claim 1 or 2, wherein the protruding portion is formed on at least the second sheet material. A laminated structure in which a plurality of sheet materials are laminated, one end communicating with a nozzle and a plurality of pressure chambers formed along a plane, communicating with the plurality of pressure chambers and on the plane A common ink chamber extending in one parallel direction, a first thin film portion constituting at least a part of a first inner wall surface parallel to the plane in the common ink chamber, and the first thin film portion. A flow path unit including a first damper chamber adjacent to the common ink chamber, and a plurality of communication passages communicating with the other end of the pressure chamber and the common ink chamber;
A plurality of actuators each for imparting ejection energy to the corresponding ink in the pressure chamber;
The common ink chamber protrudes outward from a second inner wall surface intersecting the first inner wall surface, and has a plurality of protrusions arranged in a staggered manner along the one direction. And
One end of the communication path communicates with the common ink chamber at the protrusion.
The protrusion is formed from the end on the first inner wall surface side to the opposite end on the second inner wall surface ;
The plurality of pressure chambers are arranged in a staggered matrix along the one direction to form a plurality of pressure chamber rows,
The inkjet head according to claim 1, wherein the pressure chamber row is opposed to the common ink chamber in the stacking direction of the sheet material . The inkjet head according to any one of claims 1 to 4 , wherein a cross section of the common ink chamber orthogonal to the one direction has a rectangular shape. Said communication port at the boundary between the projecting portion and the communicating passage, the ink-jet head according to any one of claims 1 to 5, wherein a plane parallel. Wherein in a plan view of the common ink chamber, the ink-jet head according to any one of claims 1 to 6, characterized in that the inner wall surface of the projecting portion is curved in an arc. The flow path unit has a third inner wall surface facing the first inner wall surface in the common ink chamber, and a second thin film portion constituting at least a part of the third inner wall surface; and ink jet head according to any one of claims 1 to 7, characterized by further comprising a second damper chamber adjacent to the common ink chamber through the second thin section.   9. The communication path according to claim 1, wherein the communication passage communicates with each other so that the inner wall surfaces thereof coincide with each other at a position farthest from the common ink chamber in the projecting portion. Inkjet head.   The other end of the pressure chamber communicates with one end of a throttle constituting the communication channel,
  The said restriction | limiting is extended in parallel with the said plane in the different position regarding the said pressure chamber and the said lamination direction while it opposes the other said adjacent pressure chamber. The inkjet head of any one of Claims. The pressure chamber communicates with the protruding portion protruding from one inner wall surface in the width direction of the common ink chamber through the restrictor, and the nozzle disposed on the outer side of the other inner wall surface. The inkjet head according to claim 10, wherein the inkjet head is in communication. It is a line type, The inkjet head of any one of Claims 1-11 characterized by the above-mentioned.

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