JP4297157B2 - Ink jet head and ink jet printer having ink jet head - Google Patents

Description

  The present invention relates to an inkjet head that performs printing by ejecting ink onto a recording medium, and an inkjet printer having the inkjet head.

  In an inkjet printer, an inkjet head distributes ink supplied from an ink tank to a plurality of pressure chambers. Ink is ejected from the nozzles connected to each pressure chamber by selectively applying a pulsed pressure to the pressure chamber by an actuator unit made of a sheet-like piezoelectric ceramic to generate a pressure wave. Printing is performed while such a head is reciprocated at high speed in the width direction of the paper.

  Regarding the arrangement of the pressure chambers in the ink jet head, there are a one-dimensional arrangement arranged in one or two rows in the longitudinal direction of the head, and a matrix-like two-dimensional arrangement along the head surface. It is more effective to arrange the pressure chambers two-dimensionally in order to achieve high resolution and high speed printing that have been required in recent years. As an example of an ink-jet head in which a pressure chamber is two-dimensionally arranged along the surface, one in which a nozzle is arranged at the center of the pressure chamber as seen from a direction perpendicular to the head surface is known (see Patent Document 1). ). In this case, when a pulsed pressure is applied to the pressure chamber, a pressure wave propagates in the direction perpendicular to the head surface in the pressure chamber, and is disposed at the center of the pressure chamber as viewed from the direction perpendicular to the head surface. Ink is ejected from the nozzles.

Japanese National Patent Publication No. 10-508808 (page 11, FIG. 3)

  However, when the nozzle is arranged in the center of the pressure chamber as viewed from the direction perpendicular to the head surface, when ink is supplied to the pressure chamber arranged in a matrix, the width of the common ink passage for supplying ink is reduced. The distance between the nozzles corresponding to the adjacent pressure chambers is limited. This is because it is necessary to arrange the common ink passage so as not to overlap the nozzle in the center of the pressure chamber when viewed from the direction perpendicular to the head surface. At this time, if the nozzles are arranged at a high density in order to meet the demand for higher resolution and higher speed of printing, the width of the common ink passage is limited. When the width of the common ink path is limited, the flow resistance to the ink in the common ink path increases, and it is not possible to smooth the ink supply corresponding to the maximum ink discharge cycle.

  Accordingly, an object of the present invention is to provide an ink jet head capable of facilitating ink supply and an ink jet printer having the ink jet head.

  In order to achieve the above object, an inkjet head of the present invention includes a plurality of nozzles that eject ink, and a plurality of pressure chambers that communicate with the nozzles and have a substantially parallelogram-shaped planar shape in a first direction. A plurality of pressure chamber rows extending in the first direction formed by being adjacently arranged in a matrix at equal intervals in a plane including the plurality of pressure chamber rows and communicating with any of the plurality of pressure chambers And a second common ink passage extending in the first direction in parallel with each other, and a pressure chamber row formed by a plurality of pressure chambers arranged in the second direction is the second The first common ink passage at the acute angle portion on one side, the first pressure chamber communicating with the first nozzle at the acute angle portion on the other side, and the other side of the first pressure chamber, 1st in the acute angle part on one side A common ink passage, a second pressure chamber communicating with the second nozzle at the acute angle portion on the other side, and a second nozzle adjacent to the other side of the second pressure chamber, and a third nozzle at the other side, the other side A third pressure chamber communicating with the second common ink passage at the acute angle portion of the third pressure chamber, adjacent to the other side of the third pressure chamber, the fourth nozzle at the acute angle portion on the one side, and the other side. A fourth pressure chamber communicating with the second common ink passage at the acute angle portion on the side, and in plan view, the first nozzle, the second nozzle, the third nozzle, and the A fourth nozzle is disposed between the first common ink passage and the second common ink passage.

  According to the above configuration, for the pressure chamber rows each constituted by the first pressure chamber and the second pressure chamber, and the pressure chamber rows each constituted by the third pressure chamber and the fourth pressure chamber, By disposing one common ink path for each, the number of common ink paths can be reduced and the width of the common ink path can be increased, so that the flow resistance is reduced and ink is supplied smoothly.

  In the inkjet head of the present invention, the plurality of pressure chambers and the common ink passage are connected via an aperture, and the aperture has a height different from that of the pressure chamber in a direction orthogonal to a plane. You may arrange | position substantially parallel to a plane. This eliminates the need to provide a common ink passage for each pressure chamber row. In addition, the pressure chamber can be highly integrated, and high-resolution image formation can be realized with an inkjet head having a relatively small occupation area.

  In the ink jet head of the present invention, the aperture is arranged in a pressure chamber of a pressure chamber row adjacent to the pressure chamber row arranged in the first direction to which the pressure chamber to which the aperture is connected belongs in a plan view. It may overlap. According to this, the pressure chamber can be highly integrated, and high-resolution image formation can be realized by the ink jet head having a relatively small occupation area.

  In the ink jet head of the present invention, each of the first pressure chambers includes a plurality of the pressure chamber rows and is arranged so as to be overlapped with each other with respect to a direction orthogonal to the first direction. The number of pressure chambers included in each of the pressure chamber rows of the first pressure chamber row group and the second pressure chamber row group in the overlapped portion, each having a row group and a second pressure chamber row group Is less than the non-overlapping portion, and the total of the pressure chambers included in the pressure chamber row in the first pressure chamber row group and the second pressure chamber row group does not overlap. It may be equal to the number of pressure chambers included in the pressure chamber row in the portion. According to this, the pressure chambers existing along the width direction of the flow path unit can complement each other, and a small inkjet head having a very narrow width can be obtained while realizing high resolution printing.

  In the ink jet head of the present invention, the plurality of pressure chamber rows constituting the first pressure chamber row group and the plurality of pressure chamber rows constituting the second pressure chamber row group are each in the third direction. The first pressure chamber row is located in a trapezoidal region as viewed from the above, and the first pressure chamber row group and the second pressure chamber row group are adjacent to each other in a direction orthogonal to the first direction. The trapezoidal hypotenuse corresponding to the group and the trapezoid hypotenuse corresponding to the second pressure chamber row group are alternately arranged in a staggered manner along the first direction, and viewed from the third direction. The ink in the pressure chamber is ejected from the nozzle at a position overlapping the trapezoid corresponding to the first pressure chamber row group and the second pressure chamber row group. Trapezoidal shape that generates pressure Effectuator eta units may be disposed. According to this, the pressure chambers existing along the width direction of the flow path unit can complement each other, and a small inkjet head having a very narrow width can be obtained while realizing high resolution printing.

The inkjet head of the present invention includes a plurality of nozzles that eject ink, and a plurality of pressure chambers that are in communication with the nozzles and have a substantially parallelogram-shaped planar shape, in the first direction and the first direction. A plurality of pressure chamber rows formed by being arranged adjacent to each other at equal intervals in the second direction intersecting each other so as to communicate with any one of the plurality of pressure chambers and straddle the plurality of pressure chamber rows. A common ink passage extending in the first direction in parallel,
The pressure chamber row formed by arranging the plurality of pressure chambers in the second direction communicates with the first nozzle at one acute angle portion and the common ink passage at the other acute angle portion, respectively. A second pressure chamber adjacent to the other side of the first pressure chamber and communicating with the second nozzle on the one side and the common ink passage on the other side, and the second pressure A third pressure chamber adjacent to the other side of the chamber, communicating with the common ink passage on the one side, and a third nozzle on the other side, and adjacent to the other side of the third pressure chamber. The fourth ink chamber communicates with the common ink passage on the one side and the fourth nozzle on the other side, and the common ink passage is connected to the second nozzle and the third nozzle in a plan view. With nozzle It is disposed between.

  According to the above configuration, the number of common ink passages can be reduced and the width of the common ink passages can be increased, so that the flow path resistance is reduced and ink is supplied smoothly.

  In the ink jet head of the present invention, even if the second pressure chamber and the third pressure chamber overlapping one common ink passage in a plan view overlap when viewed from the first direction. Good.

  In the inkjet head of the present invention, the pressure chamber and the common ink passage are connected via an aperture, and the aperture is disposed at a height different from that of the pressure chamber in a direction orthogonal to a plane. May be. According to this, the pressure chamber can be highly integrated, and high-resolution image formation can be realized by the ink jet head having a relatively small occupation area.

  In the ink jet head of the present invention, the aperture is a pressure chamber in a pressure chamber row adjacent to the pressure chamber row arranged in the first direction to which the pressure chamber connected to the aperture belongs in a plan view. May overlap. According to this, the pressure chamber can be highly integrated, and high-resolution image formation can be realized by the ink jet head having a relatively small occupation area.

  In the ink jet head of the present invention, each of the first pressure chambers includes a plurality of the pressure chamber rows, and is arranged so as to be overlapped with each other with respect to a direction orthogonal to the extending direction of the common ink passage. Pressure chamber row groups and second pressure chamber row groups, and the pressures included in the pressure chamber rows of the first pressure chamber row group and the second pressure chamber row group in the overlapped portion, respectively. The number of chambers is smaller than that of the non-overlapping portion, and the total number of pressure chambers included in the pressure chamber row in the first pressure chamber row group and the second pressure chamber row group is the overlap. It may be equal to the number of pressure chambers included in the pressure chamber row in the portion that is not. According to this, the pressure chambers existing along the width direction of the flow path unit can complement each other, and a small inkjet head having a very narrow width can be obtained while realizing high resolution printing.

  In the ink jet head of the present invention, the plurality of pressure chamber rows constituting the first pressure chamber row group and the plurality of pressure chamber rows constituting the second pressure chamber row group are each in the third direction. The first pressure chamber row is located in a trapezoidal region as viewed from the above, and the first pressure chamber row group and the second pressure chamber row group are adjacent to each other in a direction orthogonal to the first direction. The trapezoidal hypotenuse corresponding to the group and the trapezoid hypotenuse corresponding to the second pressure chamber row group are alternately arranged in a staggered manner along the first direction, and viewed from the third direction. The ink in the pressure chamber is ejected from the nozzle at a position overlapping the trapezoid corresponding to the first pressure chamber row group and the second pressure chamber row group. Trapezoidal shape that generates pressure Effectuator eta units may be disposed. According to this, the pressure chambers existing along the width direction of the flow path unit can complement each other, and a small inkjet head having a very narrow width can be obtained while realizing high resolution printing.

  In the ink jet head of the present invention, the arrangement direction of the pressure chamber rows is the second direction that forms an acute angle with the first direction, and a straight line along the first direction of the plurality of nozzles. Adjacent ones of upward projection lines may be separated by a predetermined distance. According to this, it becomes possible to draw a straight line extending in the first direction with a constant resolution as a whole.

  The inkjet head of the present invention communicates with a plurality of nozzles that eject ink, a plurality of common ink passages extending in parallel with each other in a first direction, one end communicating with the nozzles, and the other end communicating with the common ink passages. And a plurality of pressure chambers having a substantially parallelogram planar shape with rounded corners, and two-dimensionally adjacent to each other along the plane including the first direction, and the common ink An actuator unit that generates pressure in the ink in the pressure chamber in order to discharge the ink supplied from the passage from the nozzle, and in the plane partitioned in correspondence with the arrangement of the plurality of pressure chambers A plurality of parallelogram regions, each having a planar shape substantially similar to the pressure chamber, include the pressure chambers one by one in plan view and share one oblique side with each other A first parallelogram region disposed adjacent to a second direction having an acute angle with the first direction and having a first nozzle at an acute angle portion on one side with respect to the second direction; A first parallelogram region adjacent to the one side and a second parallelogram region having a second nozzle at an acute angle portion on one side; and adjacent to the one side of the second parallelogram region. And a third parallelogram region having a third nozzle at the acute angle portion on the other side, and a fourth nozzle adjacent to one side of the third parallelogram region and at the acute angle portion on the other side. A parallelogram area group including a fourth parallelogram area and the common ink passage is at least one of the first parallelogram area and the fourth parallelogram area in plan view. If it overlaps one area and overlaps the first parallelogram area When the one side wall extending in the first direction is adjacent to the other side of the first nozzle and overlaps the fourth parallelogram region, the side wall extending in the first direction The other side wall is disposed so as to be close to the one side of the fourth nozzle.

  According to the above configuration, the number of common ink passages can be reduced and the width of the common ink passages can be increased, so that the flow path resistance is reduced and ink is supplied smoothly.

  In the ink jet head of the present invention, the projection lines onto the straight line along the first direction of the first to fourth nozzles do not overlap each other, and the projection lines of the first nozzle And the projection line in the third nozzle may be equal to the interval between the projection line in the second nozzle and the projection line in the fourth nozzle. According to this, it becomes possible to draw a straight line extending in the first direction with a constant resolution as a whole.

  In the inkjet head of the present invention, the plurality of parallelogram regions are arranged in the first direction to form a parallelogram region row, and the plurality of parallelogram region rows are the second region. Arranged in a direction, and in the first direction, has a width that is the same length as a separation distance between two pressure chambers adjacent to each other in the first direction, and traverses the actuator unit. In the belt-like region extending in the direction orthogonal to the first direction, there is one nozzle belonging to each parallelogram region row, and on the straight line along the first direction of the nozzle. Adjacent projection lines to each other may be separated at equal intervals corresponding to the resolution at the time of printing. According to this, it becomes possible to draw a straight line extending in the first direction with a constant resolution as a whole.

  The ink jet printer of the present invention includes the ink jet head according to any one of claims 1 to 15.

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

  FIG. 1 is a schematic view of an inkjet printer including an inkjet head according to an embodiment of the present invention. An ink jet printer 101 shown in FIG. 1 is a color ink jet printer having four ink jet heads 1. The printer 101 includes a paper feed unit 111 on the left side in the drawing and a paper discharge unit 112 on the right side in the drawing.

  Inside the printer 1, a paper transport path is formed through which paper is transported from the paper feed unit 111 toward the paper discharge unit 112. A pair of feed rollers 105 a and 105 b that sandwich and convey a sheet as an image recording medium are disposed immediately downstream of the sheet feeding unit 111. The paper is fed from the left to the right in the figure by the pair of feed rollers 105a and 105b. Two belt rollers 106 and 107 and an endless conveyance belt 108 wound around the rollers 106 and 107 are disposed in the middle of the sheet conveyance path. The outer peripheral surface of the conveyor belt 108, i.e., the conveyor surface, is subjected to silicone treatment. While the sheet conveyed by the pair of feed rollers 105 a and 105 b is held on the conveyor surface of the conveyor belt 108 by its adhesive force, The belt roller 106 can be conveyed toward the downstream side (right side) by being rotated clockwise (in the direction of the arrow 104) in the drawing.

  Holding members 109a and 109b are disposed at the insertion and discharge positions of the sheet with respect to the belt roller 106, respectively. The holding members 109a and 109b are for pressing the paper against the transport surface of the transport belt 108 so that the paper on the transport belt 108 is not lifted from the transport surface so as to securely adhere to the transport surface.

  A peeling mechanism 110 is provided immediately downstream of the conveying belt 108 along the sheet conveying path. The peeling mechanism 110 is configured to peel the paper adhered to the conveyance surface of the conveyance belt 108 from the conveyance surface and send it to the right paper discharge unit 112.

  The four inkjet heads 1 have a head main body 1a (a flow path unit in which an ink flow path including a pressure chamber is formed, and an actuator unit that applies pressure to the ink in the pressure chamber are bonded to the lower ends of the four inkjet heads 1). Is). The head main bodies 1a each have a rectangular cross section, and are arranged close to each other so that the longitudinal direction thereof is a direction perpendicular to the paper transport direction (the direction perpendicular to the paper surface in FIG. 1). That is, the printer 101 is a line printer. The bottom surfaces of the four head main bodies 1a are opposed to the sheet conveyance path, and nozzles on which a large number of ink discharge ports having minute diameters are formed are provided on these bottom surfaces. Magenta, yellow, cyan, and black inks are ejected from each of the four head bodies 1a.

  The head main body 1a is disposed so that a small amount of gap is formed between the lower surface of the head main body 1a and the conveyance surface of the conveyance belt 108, and a sheet conveyance path is formed in the gap portion. With this configuration, when the paper transported on the transport belt 108 sequentially passes immediately below the four head bodies 1a, each color ink is ejected from the nozzle toward the upper surface of the paper, that is, the printing surface. A desired color image can be formed on the paper.

  The inkjet printer 101 includes a maintenance unit 117 for automatically performing maintenance on the inkjet head 1. The maintenance unit 117 is provided with four caps 116 for covering the lower surfaces of the four head bodies 1a, a purge mechanism (not shown), and the like.

  The maintenance unit 117 is located at a position (retracted position) immediately below the sheet feeding unit 111 when printing is performed by the inkjet printer 101. When a predetermined condition is satisfied after the printing is finished (for example, when a state where the printing operation is not performed continues for a predetermined time or when the printer 101 is turned off), the four head bodies It moves to a position immediately below 1a, and at this position (cap position), the cap 116 covers the lower surface of the head body 1a, respectively, and prevents the ink in the nozzle portion of the head body 1a from drying out. .

  The belt rollers 106 and 107 and the conveyor belt 108 are supported by a chassis 113. The chassis 113 is placed on a cylindrical member 115 disposed below the chassis 113. The cylindrical member 115 is rotatable around a shaft 114 attached at a position off the center. Therefore, if the upper end height of the cylindrical member 115 changes with the rotation of the shaft 114, the chassis 113 moves up and down accordingly. When the maintenance unit 117 is moved from the retracted position to the cap position, the cylindrical member 115 is rotated in advance by an appropriate angle so that the chassis 113, the conveyor belt 108, and the belt rollers 106 and 107 are moved by an appropriate distance from the position shown in FIG. It is necessary to secure the space for the maintenance unit 117 to move down.

  In a region surrounded by the conveyor belt 108, a substantially rectangular parallelepiped shape (supporting the conveyor belt 108 and the conveyor belt 108) is supported from the inner peripheral side by contacting the lower surface of the conveyor belt 108 at a position facing the inkjet head 1, ie, the upper side. A guide 121 having the same width is disposed.

  Next, the structure of the inkjet head 1 according to the present embodiment will be described in more detail. FIG. 2 is a perspective view of the inkjet head 1. FIG. 3 is a cross-sectional view taken along the line II-II in FIG. As shown in FIGS. 2 and 3, the inkjet head 1 according to the present embodiment includes a head body 1a having a rectangular planar shape extending in one direction (main scanning direction), and a base for supporting the head body 1a. 131. In addition to the head main body 1a, the base 131 supports a driver IC 132 and a substrate 133 that supply drive signals to the individual electrodes 35a and 35b (see FIGS. 6 and 10).

  As shown in FIG. 2, the base 131 is partially bonded to the upper surface of the head main body 1 a so as to support the head main body 1 a, and is bonded to the upper surface of the base block 138 so as to adhere to the base block 138. It is comprised from the holder 139 which hold | maintains. The base block 138 is a substantially rectangular parallelepiped member having substantially the same length as the length of the head body 1a in the longitudinal direction. The base block 138 made of a metal material such as stainless steel has a function as a lightweight structure that reinforces the holder 139. The holder 139 includes a holder main body 141 disposed on the head main body 1a side, and a pair of holder support portions 142 extending from the holder main body 141 to the opposite side of the head main body 1a. Each of the pair of holder support portions 142 is a flat plate-like member, and is provided in parallel with each other at a predetermined interval along the longitudinal direction of the holder main body 141.

  A pair of skirt portions 141a projecting downward are provided at both ends of the holder main body 141 in the sub-scanning direction (direction orthogonal to the main scanning direction). Here, since each of the pair of skirt parts 141a is formed over the entire width in the longitudinal direction of the holder body 141, a substantially rectangular parallelepiped groove part 141b is formed on the lower surface of the holder body 141 by the pair of skirt parts 141a. ing. A base block 138 is accommodated in the groove 141b. The upper surface of the base block 138 and the bottom surface of the groove 141b of the holder main body 141 are bonded with an adhesive. Since the thickness of the base block 138 is slightly larger than the depth of the groove portion 141b of the holder main body 141, the lower end portion of the base block 138 protrudes downward from the skirt portion 141a.

  Inside the base block 138, an ink reservoir 3 is formed as a flow path for ink supplied to the head body 1a, which is a substantially rectangular parallelepiped gap (hollow region) extending in the longitudinal direction. An opening 3 b (see FIG. 4) communicating with the ink reservoir 3 is formed on the lower surface 145 of the base block 138. The ink reservoir 3 is connected to a main ink tank (ink supply source) (not shown) in the printer main body by a supply tube (not shown). For this reason, the ink reservoir 3 is appropriately replenished with ink from the main ink tank.

  The lower surface 145 of the base block 138 protrudes downward from the periphery in the vicinity of the opening 3b. The base block 138 is in contact with the flow path unit 4 (see FIG. 3) of the head main body 1a only at the portion 145a in the vicinity of the opening 3b of the lower surface 145. Therefore, a region other than the portion 145a in the vicinity of the opening 3b on the lower surface 145 of the base block 138 is separated from the head main body 1a, and the actuator unit 21 is disposed in this separated portion.

  A driver IC 132 is fixed to the outer surface of the holder support portion 142 of the holder 139 via an elastic member 137 such as a sponge. A heat sink 134 is disposed in close contact with the outer surface of the driver IC 132. The heat sink 134 is a substantially rectangular parallelepiped member and efficiently dissipates heat generated by the driver IC 132. Connected to the driver IC 132 is a flexible printed circuit (FPC) 136 that is a power supply member. The FPC 136 connected to the driver IC 132 is electrically joined to the substrate 133 and the head main body 1a by soldering. A substrate 133 is disposed above the driver IC 132 and the heat sink 134 and outside the FPC 136. The upper surface of the heat sink 134 and the substrate 133 and the lower surface of the heat sink 134 and the FPC 136 are bonded by a seal member 149, respectively.

  A seal member 150 is disposed between the lower surface of the skirt portion 141 a of the holder main body 141 and the upper surface of the flow path unit 4 so as to sandwich the FPC 136. That is, the FPC 136 is fixed to the flow path unit 4 and the holder main body 141 by the seal member 150. As a result, it is possible to prevent bending when the head main body 1a is elongated, prevent stress from being applied to the connecting portion between the actuator unit 21 and the FPC 136, and reliably hold the FPC 136.

  As shown in FIG. 2, six convex portions 30 a are equally spaced along the side wall of the inkjet head 1 in the vicinity of the lower corner along the main scanning direction of the inkjet head 1. These sheet-like members are portions provided at both ends in the sub-scanning direction of the nozzle plate 30 (see FIG. 7) in the lowermost layer of the head body 1a. That is, the nozzle plate 30 is bent about 90 degrees along the boundary line between the protruding portion 30a and the other portions. The protruding portions 30a are provided at positions corresponding to the vicinity of both ends of various sizes of paper used for printing in the printer 101. Since the bent portion of the nozzle plate 30 has a rounded shape rather than a right angle, the paper is jammed when the leading edge of the paper conveyed in the direction close to the head 1 contacts the side surface of the head 1. That is, jamming is less likely to occur.

  FIG. 4 is a schematic plan view of the head main body 1a. In FIG. 4, the ink reservoir 3 formed in the base block 138 is virtually drawn with a broken line. As shown in FIG. 4, the head main body 1a has a rectangular planar shape extending in one direction (main scanning direction). The head main body 1a has a flow path unit 4 in which a large number of pressure chambers 10 and ink discharge ports 8 (see FIGS. 5, 6, and 7), which will be described later, are formed. A plurality of trapezoidal actuator units 21 arranged in two rows in a staggered manner are bonded. Each actuator unit 21 is arranged such that its parallel opposing sides (upper side and lower side) are along the longitudinal direction of the flow path unit 4. The oblique sides of the adjacent actuator units 21 overlap in the width direction of the flow path unit 4.

  The lower surface of the flow path unit 4 corresponding to the adhesion area of the actuator unit 21 is an ink ejection area. On the surface of the ink discharge region, as will be described later, a large number of ink discharge ports 8 are arranged in a matrix. An ink reservoir 3 is formed in the base block 138 disposed above the flow path unit 4 along the longitudinal direction thereof. The ink reservoir 3 communicates with an ink tank (not shown) through an opening 3a provided at one end thereof, and is always filled with ink. In the ink reservoir 3, two openings 3b are paired along the extending direction, and are provided in a staggered manner corresponding to a region where the actuator unit 21 is not provided.

  FIG. 5 is an enlarged view of a region surrounded by a one-dot chain line drawn in FIG. As shown in FIGS. 4 and 5, the ink reservoir 3 communicates with the manifold 5 in the flow path unit 4 in the lower layer through the opening 3b. The opening 3b is provided with a filter (not shown) for capturing dust contained in the ink. The manifold 5 has a sub-manifold 5a with its tip portion branched into two. Two sub-manifolds 5 a enter the lower part of one actuator unit 21 from two openings 3 b adjacent to the actuator unit 21 in the longitudinal direction of the inkjet head 1. That is, a total of four sub-manifolds 5 a extend along the longitudinal direction of the inkjet head 1 at the bottom of one actuator unit 21. The sub-manifolds 5a function as common ink passages, each of which is filled with ink supplied from the ink reservoir 3.

  FIG. 6 is an enlarged view of a region surrounded by a dashed line drawn in FIG. 5 and 6 show a state in which a plane in which a large number of pressure chambers 10 in the flow path unit 4 are arranged in a matrix is viewed from the vertical direction. The pressure chamber 10, the aperture 12, the nozzle 8, the sub-manifold, and the like, which are constituent elements of the flow path unit 4, are arranged at different heights in the direction perpendicular to the paper surface of FIGS. (See FIG. 7).

  The plurality of pressure chambers 10 are connected to nozzles (FIGS. 5 and 6 show an ink discharge port 8 formed at the tip of the nozzle) and the surface of the trapezoidal ink discharge region shown in FIG. A matrix shape in two directions of the arrangement direction A (first direction) and the arrangement direction B (the direction of the hypotenuse along the vertical direction of the rhombus region 10x depicted in FIG. 6, the second direction) Is arranged. The pressure chamber 10 has a substantially rhombic planar shape (length: 900 μm, width: 350 μm) that is respectively accommodated in the rhombus regions 10x arranged in a matrix in the two directions and is rounded at the corners. The plurality of rhombus regions 10x are adjacently arranged in a matrix so as to share each side without overlapping each other. The pressure chambers 10 in each rhombus region 10x are spaced apart from each other because they are arranged in common with the corresponding rhombus region 10x. As shown in FIG. 7, each pressure chamber 10 has one end connected to a nozzle and the other end communicating with a sub-manifold 5a serving as a common ink passage.

  In FIG. 6, individual electrodes 35 a and 35 b that overlap with the pressure chamber 10 in a plan view and have a planar shape similar to the pressure chamber 10 and slightly smaller are illustrated.

  The plurality of pressure chambers 10 arranged in a matrix form a plurality of pressure chamber rows along the arrangement direction A (first direction) shown in FIG. As the pressure chamber row, the first pressure chamber row 11a and the second pressure are arranged depending on the arrangement of the nozzles connected to the pressure chamber 10 when viewed from the direction (third direction) perpendicular to the paper surface of FIG. It is divided into the chamber row 11b. The pressure chambers 10a constituting the first pressure chamber row 11a have a longer diagonal direction (second direction) of the rhombic region 10x intersecting the arrangement direction A when viewed from the direction perpendicular to the paper surface (third direction). ), The connected nozzles and the ink discharge ports 8 formed at the tip thereof are unevenly distributed on the upper side of the paper surface. That is, as shown in FIG. 6, in the pressure chambers 10a constituting the first pressure chamber row 11a in the present embodiment, the ink discharge ports 8 are arranged at the upper ends of the corresponding rhombic regions 10x. On the other hand, in the pressure chambers 10b constituting the second pressure chamber row 11b, the connected nozzles and the ink discharge ports 8 formed at the tips thereof are unevenly distributed on the lower side of the paper in the second direction. That is, as shown in FIG. 6, in the pressure chambers 10b constituting the second pressure chamber row 11b in the present embodiment, the ink discharge ports 8 are arranged at the lower end portions of the corresponding rhombic regions 10x. The first and second pressure chamber rows 11a and 11b are alternately arranged in two rows. The arrangement direction A (first direction) shown in FIG. 6 corresponds to the longitudinal direction of the inkjet head 1, and the arrangement direction B corresponds to the one oblique side direction of the rhombic region 10 x slightly inclined from the width direction of the inkjet head 1. It is.

  The sub-manifold 5a functioning as a common ink passage extends along the arrangement direction A and communicates with a plurality of pressure chambers 10 disposed on both sides of the sub-manifold 5a. The sub-manifold 5a is adjacent to each other so that the nozzle and the ink discharge port 8 at the tip of the sub-manifold 5a face outward with the sub-manifold 5a interposed therebetween as viewed from the direction perpendicular to the paper surface of FIG. 6 (third direction). The first pressure chamber row 11a and the second pressure chamber row 11b are included and extend so as not to overlap the nozzle and the ink discharge port 8 at the tip thereof. The sub-manifold 5a preferably includes most of the first and second pressure chamber rows 11a and 11b adjacent to each other within a range that does not overlap with the nozzles and the ink discharge ports 8 so that the width thereof is increased. That is, in order to smoothly supply ink to each communicating pressure chamber 10, it is preferable that the width limit of the sub-manifold 5a is close to one end where the ink discharge port 8 of the pressure chamber 10 is connected. Thereby, even when the thickness (depth) of the sub-manifold 5a in the third direction is determined, the flow path resistance with respect to the ink of the sub-manifold 5a can be reduced.

  FIG. 7 is a partial cross-sectional view of the head main body 1a depicted in FIG. As can be seen from FIG. 7, each ink discharge port 8 is formed at the tip of a tapered nozzle. In addition, the aperture 12 extends substantially parallel to the surface of the flow path unit 4 between the pressure chamber 10 and the sub-manifold 5a, like the pressure chamber 10. This aperture 12 is for restricting the flow of ink and providing an appropriate flow path resistance to stabilize ink ejection. Each ink discharge port 8 communicates with the sub-manifold 5a via the pressure chamber 10 (length 900 μm, width 350 μm) and the aperture 12. In this manner, the ink jet head 1 is formed with the ink flow path 32 from the ink tank to the ink discharge port 8 through the ink reservoir 3, the manifold 5, the sub manifold 5a, the aperture 12, and the pressure chamber 10.

  For example, if the pressure chamber 10 shown in FIG. 7 constitutes the first pressure chamber row 11a shown in FIG. 6, the second pressure chamber row 11b is formed on the right side of the sub manifold 5a. A nozzle connected to the pressure chamber 10 is arranged.

  The aperture 12 communicating with one pressure chamber 10 is disposed so as to overlap the pressure chamber 10 adjacent to the pressure chamber 10 when viewed from a direction perpendicular to the paper surface of FIG. 6 (third direction). One reason that such a possibility is possible is that the aperture 12 is provided closer to the sub-manifold 5a than the pressure chamber 10 in the direction perpendicular to the paper surface (third direction), and the pressure chamber 10 and the aperture 12 are provided. There are different heights. That is, as shown also in FIG. 7, the pressure chamber 10, the aperture 12, and the sub-manifold 5a are each formed by laminated sheet members and arranged so as to overlap each other when viewed from the third direction. ing.

  In FIGS. 5 and 6, the pressure chamber 10 and the aperture 12 which are to be drawn by broken lines below the actuator unit 21 are drawn by solid lines for easy understanding of the drawings.

  When a pressure wave is generated by applying a pulsed pressure to the pressure chamber 10 by the actuator unit 21, a pressure wave that contributes to ink ejection is generated in the pressure chamber 10 along the longer diagonal direction of the rhombic region 10x. Propagate. When the propagation direction of the pressure wave is perpendicular to the surface, the planar shape of the pressure chamber 10 is generally a shape that is symmetrical with respect to the origin, such as a circle or a regular polygon. However, when a pressure wave propagating in a specific direction along the surface of the flow path unit 4 in the pressure chamber 10 is used for ink ejection as in this embodiment, the pressure wave propagation time length (AL In order to make it easier to control the ink discharge amount and discharge cycle by increasing the length (Acoustic Length), the planar shape of the pressure chamber 10 is preferably elongated in the propagation direction of the pressure wave.

  5 and 6, the pressure chamber 10 has two longitudinal directions (arrangement direction A) of the inkjet head 1 and a direction slightly inclined from the width direction of the inkjet head 1 (arrangement direction B). They are arranged in the direction of ink discharge in the direction. The arrangement direction A and the arrangement direction B form an angle θ slightly smaller than a right angle. The ink discharge ports 8 are arranged at 50 dpi in the arrangement direction A. On the other hand, the pressure chambers 10 are arranged so that twelve pressure chambers 10 are included in the ink discharge region corresponding to one actuator unit 21 in the arrangement direction B. As a result, within the entire width of the inkjet head 1, twelve ink discharge ports 8 exist in a range separated by a distance between two ink discharge ports 8 adjacent in the arrangement direction A. In addition, at both ends (corresponding to the oblique sides of the actuator unit 21) of each ink discharge area in the arrangement direction A, the ink discharge area corresponding to another actuator unit 21 facing the width direction of the inkjet head 1 is complementary. Thus, the above condition is satisfied. Therefore, in the inkjet head 1 according to the present embodiment, the ink is sequentially ejected from the large number of ink ejection ports 8 arranged in the arrangement direction A and the arrangement direction B as the inkjet head 1 moves relative to the paper in the width direction. By ejecting the droplets, it is possible to perform printing at 600 dpi in the main scanning direction.

  Next, the structure of the flow path unit 4 will be described in more detail with reference to FIG. As shown in FIG. 8, the pressure chambers 10 are arranged in a row at a predetermined interval of 50 dpi in the arrangement direction A. Such rows of pressure chambers 10 are arranged in 12 rows in the arrangement direction B, and as a whole, the pressure chambers 10 are two-dimensionally arranged in an ink discharge region corresponding to one actuator unit 21.

  There are two types of pressure chambers 10, a pressure chamber 10 a having a nozzle connected to the upper acute angle portion in FIG. 8 and a pressure chamber 10 b connected to the lower acute angle portion in FIG. 8. The plurality of pressure chambers 10a and the plurality of pressure chambers 10b are both arranged in the arrangement direction A to form pressure chamber rows 11a and 11b, respectively. As shown in FIG. 8, in the ink ejection region corresponding to one actuator unit 21, two rows of pressure chambers 11a are arranged in order from the lower side in FIG. 8, and two rows of pressure are adjacent to the upper side. The chamber row 11b is arranged. A combination of such two pressure chamber rows 11a and two pressure chamber rows 11b and four pressure chamber rows as one set is an ink discharge corresponding to one actuator unit 21. Within the region, the sequence is repeated three times from the bottom. A straight line connecting the upper acute angle portions of the pressure chambers in the pressure chamber rows 11a and 11b intersects the lower oblique side of each pressure chamber in the pressure chamber row adjacent to the pressure chamber row from above.

  As described above, the first pressure chamber row 11a and the second pressure chamber row 11b having different arrangement positions of the nozzles connected to the pressure chamber 10 as viewed from the direction perpendicular to the paper surface of FIG. By arranging the columns adjacent to each other, the pressure chambers 10 are regularly aligned as a whole. On the other hand, the nozzles are gathered and arranged in the central region in a set of pressure chamber rows in which the four pressure chamber rows are one set. Thus, as described above, when the four pressure chamber rows are set as one set and the pressure chamber row set is repeated three times from the lower side, the region near the boundary between the pressure chamber row set and the set, that is, Regions where no nozzles are present are formed on both sides of such a set of four pressure chamber rows. A wide sub-manifold 5a for supplying ink to each pressure chamber 10 is extended there. In the present embodiment, in the ink ejection region corresponding to one actuator unit 21, one is located on the lower side in the figure, and between the lowermost pressure chamber row group and the second pressure chamber row group. In addition, four wide sub-manifolds 5a are extended in the arrangement direction A, two on each side of the uppermost pressure chamber row group.

  As shown in FIG. 8, the nozzles communicating with the ink ejection ports 8 that eject ink are arranged in the arrangement direction A at equal intervals of 50 dpi corresponding to the pressure chambers 10 regularly arranged in this direction. Further, unlike the twelve pressure chambers 10 arranged regularly in the arrangement direction B that intersects the arrangement direction A at an angle θ, the twelve nozzles corresponding to the twelve pressure chambers 10 have As described above, there are a portion communicating with the upper acute angle portion of the pressure chamber 10 and a portion communicating with the lower acute angle portion, and they are not regularly arranged in the arrangement direction B at regular intervals.

  On the other hand, when the nozzles are always in communication with the acute angle portion on the same side of the pressure chamber 10, the nozzles are also regularly arranged in the arrangement direction B at regular intervals. That is, in this case, the nozzles are arranged so as to be displaced by an interval corresponding to 600 dpi, which is the resolution at the time of printing, in the arrangement direction A every time one pressure chamber row rises from the lower side to the upper side in the drawing. On the other hand, in the present embodiment, two pressure chamber rows 11a and two pressure chamber rows 11b are combined into a set of four pressure chamber rows, and this is repeated three times from the lower side. Therefore, the displacement of the nozzle positions in the arrangement direction A every time one pressure chamber rises from the lower side to the upper side in the figure is not always the same.

  In the inkjet head 1 according to the present embodiment, a band-like region R having a width (about 508.0 μm) corresponding to 50 dpi in the arrangement direction A and extending in a direction orthogonal to the arrangement direction A will be considered. In the belt-like region R, there is only one nozzle for any of the twelve pressure chamber rows. That is, when such a belt-like region R is partitioned at an arbitrary position in the ink discharge region corresponding to one actuator unit 21, twelve nozzles are always distributed in the belt-like region R. The positions of the points where these 12 nozzles are projected on a straight line extending in the arrangement direction A are separated by an interval corresponding to 600 dpi, which is the resolution at the time of printing.

  The twelve nozzles belonging to one belt-like region R are designated as (1) to (12) in order from the left of the projected position on a straight line extending in the arrangement direction A. These twelve nozzles are (1), (7), (2), (8), (5), (11), (6), (12), (9), (3 ), (10), (4).

  In the inkjet head 1 according to the present embodiment configured as described above, when the active layer in the actuator unit 21 is appropriately driven, characters, figures, and the like having a resolution of 600 dpi can be drawn. That is, specific characters and figures can be printed on the print medium by selectively driving the active layers corresponding to the 12 pressure chamber rows sequentially in accordance with the conveyance of the print medium.

  For example, a case where a straight line extending in the arrangement direction A is printed with a resolution of 600 dpi will be described. First, the case where the nozzle communicates with the acute angle portion on the same side of the pressure chamber 10 will be briefly described. In this case, in response to the printing butterfly being transported, ink discharge is started from the nozzles in the pressure chamber row located at the bottom in FIG. 8, and sequentially belongs to the pressure chamber row adjacent to the upper side. Select a nozzle to eject ink. As a result, ink dots are formed while being adjacent to each other in the arrangement direction A at an interval of 600 dpi. Eventually, a straight line extending in the arrangement direction A is drawn with a resolution of 600 dpi as a whole.

  On the other hand, in the present embodiment, ink discharge starts from the nozzles in the pressure chamber row 11a located at the bottom in FIG. 8, and sequentially communicates with the pressure chambers adjacent to the upper side as the print medium is conveyed. The nozzle to be selected is selected and ink is ejected. At this time, since the displacement of the nozzle position in the arrangement direction A is not always the same every time one pressure chamber line rises from the lower side to the upper side, it is sequentially formed along the arrangement direction A as the print medium is conveyed. Ink dots are not evenly spaced at 600 dpi.

  That is, as shown in FIG. 8, in response to the printing medium being transported, first, ink is ejected from the nozzle (1) communicating with the lowermost pressure chamber row 11a in the figure, and onto the printing medium. Dot rows are formed at intervals corresponding to 50 dpi (about 508.0 μm). Thereafter, when the straight line formation position reaches the position of the nozzle (7) communicating with the second pressure chamber row 11a from the bottom along with the conveyance of the printing medium, ink is ejected from the nozzle (7). As a result, the second position is shifted to the position (about 42.3 μm × 6 = about 254.0 μm) displaced in the arrangement direction A by 6 times the interval corresponding to 600 dpi (about 42.3 μm) from the initially formed dot position. Ink dots are formed.

  Next, when the straight line formation position reaches the position of the nozzle (2) communicating with the third pressure chamber row 11b from the bottom along with the conveyance of the print medium, ink is ejected from the nozzle (2). As a result, a third ink dot is formed at a position displaced in the arrangement direction A by an interval corresponding to 600 dpi (about 42.3 μm) from the initially formed dot position. Further, as the printing medium is conveyed, when the straight line formation position reaches the position of the nozzle (8) communicating with the fourth pressure chamber row 11b from the bottom, ink is ejected from the nozzle (8). As a result, 4 positions are displaced from the position of the first dot formed in the arrangement direction A by 7 times the interval corresponding to 600 dpi (about 42.3 μm) (about 42.3 μm × 7 = about 296.3 μm). A second ink dot is formed. Further, when the printing medium is conveyed and the straight line formation position reaches the position of the nozzle (5) communicating with the fifth pressure chamber row 11a from the bottom, ink is ejected from the nozzle (5). As a result, the fifth position is shifted to the position (about 42.3 μm × 4 = about 169.3 μm) displaced in the arrangement direction A by 4 times the interval corresponding to 600 dpi (about 42.3 μm) from the initially formed dot position. Ink dots are formed.

  In the same manner, ink dots are sequentially formed while selecting nozzles communicating with the pressure chambers 10 positioned from the lower side to the upper side in the drawing. At this time, if the nozzle number shown in FIG. 8 is N, the arrangement direction A from the dot position formed first is equivalent to (magnification n = N−1) × (interval corresponding to 600 dpi). An ink dot is formed at the position displaced to. When 12 nozzles have been finally selected, between the ink dots formed at an interval (about 508.0 μm) corresponding to 50 dpi by the nozzle (1) in the lowermost pressure chamber row 11a in the figure. Are connected by twelve dots formed at intervals corresponding to 600 dpi (approximately 42.3 μm), and a straight line extending in the arrangement direction A can be drawn with a resolution of 600 dpi as a whole.

  FIG. 9 is a partially exploded perspective view of the head body 1a depicted in FIG. As shown in FIGS. 7 and 9, the main part on the bottom side of the ink jet head 1 is, from above, the actuator unit 21, the cavity plate 22, the base plate 23, the aperture plate 24, the supply plate 25, and the manifold plates 26, 27, 28. The cover plate 29 and the nozzle plate 30 have a laminated structure in which a total of 10 sheet materials are laminated. 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 (hereinafter simply referred to as “a layer”) in which five piezoelectric sheets are stacked and electrodes are arranged so that three of them become active layers when an electric field is applied. The remaining two layers are designated as non-active layers. The cavity plate 22 is a metal plate provided with a number of substantially diamond-shaped openings corresponding to the pressure chambers 10. The base plate 23 is a metal plate provided with a communication hole between the pressure chamber 10 and the aperture 12 and a communication hole from the pressure chamber 10 to the ink discharge port 8 with respect to 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 ink discharge port 8 in addition to the aperture 12 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 12 and the sub-manifold 5a and a communication hole from the pressure chamber 10 to the ink discharge port 8 with respect to one pressure chamber 10 of the cavity plate 22. The manifold plates 26, 27, and 28 are metal plates each provided with a communication hole from the pressure chamber 10 to the ink discharge port 8 for one pressure chamber 10 of the cavity plate 22 in addition to the sub-manifold 5 a. The cover plate 29 is a metal plate in which a communication hole from the pressure chamber 10 to the ink discharge port 8 is provided for one pressure chamber 10 of the cavity plate 22. The nozzle plate 30 is a metal plate provided with a tapered ink discharge port 8 that functions as a nozzle for each pressure chamber 10 of the cavity plate 22.

  These ten plates 21 to 30 are stacked in alignment with each other so that an ink flow path 32 as shown in FIG. 7 is formed. The ink flow path 32 first extends upward from the sub-manifold 5a, extends horizontally at the aperture 12, then further upwards, extends horizontally again at the pressure chamber 10, and then moves away from the aperture 12 for a while. It goes from the diagonally downward direction to the ink discharge port 8 vertically downward.

  Next, the structure of the actuator unit 21 will be described. FIG. 10 is an enlarged cross-sectional view of a region surrounded by an alternate long and short dash line drawn in FIG. As shown in FIG. 10, the actuator unit 21 includes five piezoelectric sheets 41, 42, 43, 44, 45 formed to be the same with a thickness of about 15 μm. These piezoelectric sheets 41 to 45 are continuous layered flat plates (continuous flat plate layers) so as to be disposed across a number of pressure chambers 10 formed in one ink discharge region in the inkjet head 1. . Since the piezoelectric sheets 41 to 45 are arranged as a continuous flat plate layer across a large number of pressure chambers 10, the individual electrodes 35a and 35b can be arranged at high density by using, for example, a screen printing technique. Yes. For this reason, the pressure chambers 10 formed at positions corresponding to the individual electrodes 35a and 35b can be arranged with high density, and high-resolution images can be printed. In the present embodiment, the piezoelectric sheets 41 to 45 are made of a lead zirconate titanate (PZT) ceramic material having ferroelectricity.

  A common electrode 34a having a thickness of about 2 μm is interposed between the piezoelectric sheet 41 in the uppermost layer of the actuator unit 21 and the piezoelectric sheet 42 adjacent thereto below. The common electrode 34 a is a single conductive sheet that extends over almost the entire area in one actuator unit 21. Similarly, a common electrode 34b having a shape similar to the common electrode 34a and having a thickness of about 2 μm is interposed between the piezoelectric sheet 43 adjacent below the piezoelectric sheet 42 and the piezoelectric sheet 44 adjacent below the piezoelectric sheet 43. .

  The common electrodes 34a and 34b may be formed in large numbers for each pressure chamber 10 so that the projected region in the stacking direction includes the pressure chamber region, or the projected region may be a pressure region. A large number of those that are slightly smaller than the pressure chamber 10 may be formed for each pressure chamber 10 so as to be included in the chamber region, and it is not always necessary to be one conductive sheet formed on the entire surface of the sheet. However, at this time, it is necessary that the common electrodes are electrically connected so that the portions corresponding to the pressure chambers 10 all have the same potential.

  As shown in FIG. 10, individual electrodes 35 a having a thickness of about 1 μm are formed on the upper surface of the piezoelectric sheet 41 and at positions corresponding to the pressure chambers 10. The individual electrode 35a has a substantially rhombus shape in plan and has a shape similar to that of the pressure chamber 10 (length: 850 μm, width: 250 μm), and a projection region in the stacking direction is included in the pressure chamber 10 region (see FIG. 6). ). An individual electrode 35b having a planar shape similar to that of the individual electrode 35a and having a thickness of about 2 μm is interposed between the piezoelectric sheet 42 and the piezoelectric sheet 43 and corresponding to the individual electrode 35a. It should be noted that no electrode is disposed between the piezoelectric sheet 44 and the piezoelectric sheet 45 adjacent thereto below and below the piezoelectric sheet 45. Each electrode 34a, 34b, 35a, 35b is made of a metal material such as an Ag-Pd system.

  The common electrodes 34a and 34b are grounded in a region not shown. As a result, the common electrodes 34 a and 34 b are kept at the same ground potential in the regions corresponding to all the pressure chambers 10. In addition, the individual electrodes 35a and 35b are drivers via the FPC 136 including separate lead wires for each individual electrode 35a and 35b so that the potential can be controlled for each corresponding to each pressure chamber 10. It is connected to the IC 132 (see FIGS. 2 and 3). At this time, the paired individual electrodes 35a and 35b may be connected to the driver IC 132 via the same lead wire.

  In the inkjet head 1 according to the present embodiment, the piezoelectric sheets 41 to 43 are polarized in the thickness direction. Therefore, when the individual electrodes 35a and 35b are set to a different potential from the common electrodes 34a and 34b and an electric field is applied to the piezoelectric sheets 41 to 43 in the polarization direction, the portions of the piezoelectric sheets 41 to 43 to which the electric fields are applied are active layers. And stretch or contract in the thickness direction, that is, the stacking direction, and try to contract or extend in the direction perpendicular to the stacking direction, that is, the plane direction, due to the piezoelectric lateral effect. On the other hand, the remaining two piezoelectric sheets 44 and 45 are inactive layers that do not have a region sandwiched between the individual electrodes 35a and 35b and the common electrodes 34a and 34b, and therefore cannot be deformed spontaneously. That is, the actuator unit 21 includes three piezoelectric sheets 41 to 43 on the upper side (that is, apart from the pressure chamber 10) as a layer including the active layer and two piezoelectric sheets on the lower side (that is, close to the pressure chamber 10). It has a so-called unimorph type configuration in which the sheets 44 and 45 are inactive layers.

  Therefore, when the driver IC 132 is controlled so that the electric field and the polarization are in the same direction and the individual electrodes 35a and 35b are set to a predetermined positive or negative potential with respect to the common electrodes 34a and 34b, the individual electrodes of the piezoelectric sheets 41 to 43 are provided. The active layer sandwiched between 35a and 35b and the common electrodes 34a and 34b contracts in the plane direction, while the piezoelectric sheets 44 and 45 do not contract spontaneously. At this time, as shown in FIG. 10, the lower surfaces of the piezoelectric sheets 41 to 45 are fixed to the upper surfaces of the partition walls that define the pressure chambers 10 formed in the cavity plate 22. Due to the contraction, the piezoelectric sheets 41 to 45 are deformed (unimorph deformation) so as to be convex toward the pressure chamber 10. Then, the volume of the pressure chamber 10 decreases, the pressure of the ink increases, and ink is ejected from the ink ejection port 8. Thereafter, when the potentials of the individual electrodes 35a and 35b are restored, the piezoelectric sheets 41 to 45 have the original flat plate shape, and the volume of the pressure chamber 10 is restored to the original volume, so that ink is sucked from the manifold 5 side.

  As another driving method, the individual electrodes 35a and 35b are previously set at different potentials from the common electrodes 34a and 34b so that the piezoelectric sheets 41 to 45 are convexly deformed toward the pressure chamber 10, and each time there is a discharge request. Alternatively, the individual electrodes 35a and 35b can be once set to the same potential as the common electrodes 34a and 34b, and then the individual electrodes 35a and 35b can be set to a different potential from the common electrodes 34a and 34b again at a predetermined timing. In this case, at the timing when the individual electrodes 35a and 35b and the common electrodes 34a and 34b become the same potential, the piezoelectric sheets 41 to 45 return to the original shape, and the volume of the pressure chamber 10 is in an initial state (the potentials of both electrodes are The ink is sucked into the pressure chamber 10 from the manifold 5 side. After that, at the timing when the individual electrodes 35a and 35b are set to potentials different from those of the common electrodes 34a and 34b, the piezoelectric sheets 41 to 45 are deformed so as to protrude toward the pressure chamber 10, and the volume of the pressure chamber 10 decreases to reduce the ink. The pressure rises and ink is ejected.

  If the electric field direction applied to the piezoelectric sheets 41 to 43 and the polarization direction thereof are opposite, the active layer in the piezoelectric sheets 41 to 43 sandwiched between the individual electrodes 35a and 35b and the common electrodes 34a and 34b is polarized. Try to stretch in the direction perpendicular to the. Accordingly, the piezoelectric sheets 41 to 45 are deformed so as to be concave toward the pressure chamber 10 based on the piezoelectric lateral effect. For this reason, the volume of the pressure chamber 10 increases and ink is sucked from the manifold 5 side. After that, when the potentials of the individual electrodes 35a and 35b are restored, the piezoelectric sheets 41 to 45 have the original flat plate shape, and the volume of the pressure chamber 10 is restored to the original volume, and thus ink is ejected from the ink ejection port 8.

  As described above, in the inkjet head 1 according to the present embodiment, as shown in FIG. 6, the inkjet head 1 is connected to each pressure chamber 10 when viewed from the direction perpendicular to the surface of the flow path unit 4 (third direction). Nozzles (the ink discharge port 8 at the tip is shown in FIG. 6) are not provided at the center of the pressure chamber 10 but are unevenly distributed at one end, and the nozzles are unevenly distributed on the opposite sides with respect to the arrangement direction A. By arranging the sub-manifold 5a functioning as a common ink passage so as to include the boundary region between the pressure chamber rows 11a and 11b, the width of the sub-manifold 5a can be increased. Accordingly, even when the thickness (depth) of the sub-manifold 5a in the third direction is determined, the flow path resistance of the sub-manifold 5a with respect to the ink is reduced, and the ink is smoothly supplied to the pressure chamber 10. It can be carried out.

  As shown in FIG. 7, the flow path unit 4 includes an aperture 12 extending substantially parallel to the surface thereof, and each pressure chamber 10 and the submanifold 5 a are connected to each other through the aperture 12. The number of 5a can be reduced. For example, when each pressure chamber 10 and the sub-manifold 5a are directly communicated with each other without using the aperture 12, the sub-manifold 5a needs to extend along the column direction with respect to each of the pressure chamber rows 11a and 11b shown in FIG. There is. However, by connecting each pressure chamber 10 and the sub-manifold 5a via the aperture 12 as in the present embodiment, the pressure chamber 10 can be connected to the sub-manifold 5a when viewed from the third direction perpendicular to the surface of the flow path unit 4. Since ink can be supplied even if it is slightly away from the pressure chamber, it is not necessary to provide the pressure chambers 11a and 11b.

  Further, as shown in FIG. 7, the pressure chamber 10 and the aperture 12 are provided at different heights with respect to the direction (third direction) perpendicular to the surface of the flow path unit 4, so that the pressure chamber is viewed from the third direction. 10 and the aperture 12 can be overlapped. Thereby, the pressure chamber 10 can be highly integrated, and high-resolution image formation by the inkjet head 1 having a relatively small occupation area is realized.

  In addition, as shown in FIG. 6, the number of sub-manifolds 5a can be increased by alternately arranging the first pressure chamber rows 11a and the second pressure chamber rows 11b by two rows as compared with the case of a modified example described later. Can be reduced. In addition, by arranging one sub-manifold 5a for each two adjacent pressure chamber rows 11a and 11b, the width of the sub-manifold 5a can be increased, so that the flow path resistance is further reduced and the ink is reduced. Is smoothly supplied.

  In addition, it can be explained by the following consideration that it is advantageous to widen the width of the sub-manifold 5a with respect to the channel resistance. First, considering a sub-manifold having a flow path length l in a rectangular cross section having a width a and a depth b, a flow path resistance R with respect to ink passing through the sub-manifold is expressed by the following equation (1).

μ：インクの粘度

μ: Ink viscosity

  Next, when sub-manifolds having a width a / n (n: an integer of 2 or more) smaller than the sub-manifolds are arranged side by side and the overall width is a, the sub-manifolds pass. The channel resistance R ′ with respect to ink is expressed by the following equation (2).

  From the equations (1) and (2), the following equation (3) is obtained.

  Since R / R ′ <1 from equation (3), when trying to make all the flow path widths the same, it is better to provide a small number of large sub-manifolds than to provide a large number of small sub-manifolds. It can be seen that the road resistance decreases. Conversely, if the width of the sub-manifold is wide, the flow resistance to the ink becomes small and the ink is easily supplied, so that the width is smaller than the predetermined number of pressure chambers and pressure chamber rows. It can be said that, when a small number of submanifolds having a large width are provided rather than a large number of small submanifolds, ink can be supplied without excess or deficiency even when the entire flow path width is reduced.

  The width of the sub-manifold 5a may be determined within a range where ink can be supplied to each pressure chamber 10 without excess or deficiency. In the present embodiment, one sub-manifold 5a is extended to the vicinity of the nozzles for each two adjacent pressure chamber rows 11a and 11b.

  Further, the sub-manifold 5a of the present embodiment is arranged such that the ink discharge ports 8 of the nozzles connected to the pressure chambers 10 face outward when viewed from the direction (third direction) perpendicular to the surface of the flow path unit 4. , Including most of one first pressure chamber row 11a and one second pressure chamber row 11b adjacent to each other. As described above, by widening the width of the sub-manifold 5a in a range that does not overlap the nozzle and the ink discharge port 8 at the tip thereof, the flow resistance of the sub-manifold 5a can be further reduced to facilitate the ink supply. .

  In addition, since the propagation direction of the pressure wave in the pressure chamber 10 is substantially parallel to the surface of the flow path unit 4, the ink is ejected using the AL length as compared with the case where the propagation direction is perpendicular to the surface of the flow path unit 4. Control becomes easy. When the AL length is short, ink is generally ejected by so-called “pushing”. However, when the AL length is long as in the present embodiment, “pushing” is performed using the reversal reflection of pressure waves. “Strike” with a smaller input energy (only the pressure chambers 10 for which ink discharge operation is to be performed by applying a voltage to all the individual electrodes 35a and 35b in advance to reduce the volume of all the pressure chambers 10). The pressure wave propagating in the pressure chamber 10 is reduced by releasing the voltage of the individual electrodes 35a and 35b and expanding the volume, and then applying the voltage to the individual electrodes 35a and 35b again to reduce the volume of the pressure chamber 10. This makes it possible to afford time for performing the method of efficiently applying the ejection pressure to the ink. Therefore, energy efficiency can be improved as compared with the case where the propagation direction of the pressure wave is perpendicular to the surface of the pressure chamber 10.

  Moreover, since the flow path unit 4 is formed by laminating nine sheet members 22 to 30 each having an opening corresponding to each, the flow path unit 4 can be easily manufactured.

  Further, in the head main body 1 a of the inkjet head 1, a plurality of actuator units 21 divided for each ink discharge region are arranged along the longitudinal direction in a state of being bonded to the flow path unit 4. As a result, each actuator unit 21 can be aligned with the flow path unit 4 for each actuator unit 21 that is likely to vary in dimensional accuracy because it is formed by sintering or the like. An increase in the amount of misalignment between the channel unit 4 and the flow path unit 4 is suppressed, and both can be accurately aligned. Therefore, the individual electrodes 35a and 35b that are relatively far from the mark are also less likely to be greatly displaced from the predetermined positions with respect to the pressure chamber 10, and the manufacturing yield of the inkjet head 1 is dramatically improved. On the other hand, when the actuator unit 21 is formed as an elongated body similar to the flow path unit 4, the individual electrodes 35 a for the pressure chambers 10 in plan view when the actuator unit 21 is overlapped with the flow path unit 4, The amount of deviation of the position 35b from the predetermined position increases with distance from the mark, the ink discharge performance in the pressure chamber 10 relatively far from the mark deteriorates, and the uniformity of the ink discharge performance within the inkjet head 1 is reduced. It will be lost.

  In the actuator unit 21, since the piezoelectric sheets 41 to 43 are sandwiched between the common electrodes 34a and 34b and the individual electrodes 35a and 35b, the volume of the pressure chamber 10 can be easily changed by the piezoelectric effect. Moreover, since the piezoelectric sheets 41 to 45 are continuous layered flat plates (continuous flat plate layers), the actuator unit 21 can be easily manufactured.

  Further, the inkjet head 1 has an actuator unit 21 having a unimorph structure in which the piezoelectric sheets 44 and 45 close to the pressure chamber 10 are inactive layers and the piezoelectric sheets 41 to 43 separated from the pressure chamber 10 are layers including the active layers. is doing. Therefore, the volume change amount of the pressure chamber 10 can be increased by the piezoelectric lateral effect, and the individual electrode 35a, compared with the actuator unit in which the active layer is disposed on the pressure chamber 10 side and the inactive layer is disposed on the opposite side. It is possible to reduce the driving voltage of 35b and / or to increase the integration of the pressure chamber 10. By reducing the drive voltage, the driver for driving the individual electrodes 35a and 35b can be reduced in size and the cost can be reduced, and the pressure chamber 10 can be made smaller and higher integration can be achieved. In addition, a sufficient amount of ink can be ejected, and the head 1 can be downsized and high-density arrangement of printing dots can be realized.

  Furthermore, as described above, in the head body 1 a of the inkjet head 1, each actuator unit 21 has a substantially trapezoidal shape, and the parallel opposing sides of each actuator unit 21 are along the longitudinal direction of the flow path unit 4. A plurality of actuator units 21 are arranged in a staggered manner so that the oblique sides of adjacent actuator units 21 overlap in the width direction of the flow path unit 4. In this way, the oblique sides of the adjacent actuator units 21 overlap each other, so that the pressure chambers 10 existing along the width direction of the flow path unit 4 are complemented in the longitudinal direction of the inkjet head 1. Thus, the small inkjet head 1 having a very narrow width can be obtained while realizing high-resolution printing.

  The preferred embodiments of the present invention have been described above, but 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 arrangement direction of the plurality of pressure chambers 10 arranged in a matrix along the surface of the flow path unit 4 is shown in FIG. 6 in the above embodiment as long as it is along the surface of the flow path unit 4. The arrangement directions are not limited to A and B, and various directions may be taken. A modification of the arrangement of the pressure chambers 10 in the flow path unit 4 is shown in FIG. In FIG. 11, the angle θ formed by the arrangement direction A and the arrangement direction B is different from that in FIG. 6, and is a smaller angle. Further, the relationship between the arrangement direction A and the arrangement direction B and the longer diagonal direction of the rhombic region 10x is also different from that shown in FIG. Is also making a big angle.

  Further, as a modification of the arrangement of the pressure chambers 10 in the flow path unit 4, there is one in which the first pressure chamber rows 11a and the second pressure chamber rows 11b are alternately arranged one by one as shown in FIG. . The pressure chambers 10 constituting the second pressure chamber row 11b enter the regions between the pressure chambers 10 adjacent to each other in the arrangement direction A constituting the first pressure chamber row 11a from above in the drawing. Is arranged. In this region, a pressure chamber 10 constituting another second pressure chamber row 11b is disposed from the lower side of the drawing. Similarly, in the region between the pressure chambers 10 adjacent to each other in the arrangement direction A constituting the second pressure chamber row 11b, the first pressure chamber row 11a is constituted from the upper side and the lower side, respectively. It arrange | positions so that the pressure chamber 10 may enter. For this reason, compared with the case of the above-mentioned embodiment shown in FIG. 6, the width | variety of the submanifold 15a becomes narrow. However, in the case where the ink discharge port 8 is configured to be unevenly distributed on one side with respect to the longer diagonal direction of the rhombus region 10x, or the ink discharge port 8 is disposed in the center of the pressure chamber 10. Compared to the case where the distance between the ink discharge ports 8 in the adjacent pressure chamber row does not increase as in the case where the pressure manifold is configured, the width of the sub-manifold 15a becomes wider. Accordingly, the flow path resistance of the sub-manifold 5a with respect to the ink is reduced, and the ink can be smoothly supplied to the pressure chamber 10.

  In addition, the region in which the pressure chamber 10 is accommodated may have various shapes such as a parallelogram instead of a rhombus, and the planar shape of the pressure chamber 10 itself contained therein may be appropriately changed to a parallelogram or the like. Although high integration of the pressure chamber 10 cannot be expected, the pressure chamber 10 does not have to be elongated in the propagation direction of the pressure wave.

  Further, although not preferable from the viewpoint of stabilizing ink ejection, the pressure chamber 10 and the sub-manifold 5a may be directly communicated with each other without the aperture 12. Further, the aperture 12 may be provided at the same height as the pressure chamber 10 in the third direction perpendicular to the surface of the flow path unit 4. However, in this case, since the pressure chamber 10 and the aperture 12 cannot be overlapped when viewed from the direction (third direction) perpendicular to the surface of the flow path unit 4, the pressure chamber 10 cannot be highly integrated.

  From the viewpoint of reducing the flow resistance, it is preferable that the sub-manifold 5a includes most of the pressure chamber rows 11a and 11b adjacent to each other, but at least the boundary region between these rows may be included.

  Further, the propagation direction of the pressure wave in the pressure chamber 10 may not be along the plane of the flow path unit 4.

  Moreover, the flow path unit 4 may not be a laminate of a plurality of sheet members.

  Moreover, the material of the piezoelectric sheet and the electrode in the actuator unit 21 is not limited to the above-described materials, and may be changed to other known materials. Moreover, you may use insulating sheets other than a piezoelectric sheet as an inactive layer. Further, the number of layers including the active layer, the number of inactive layers, and the like may be appropriately changed. For example, in the above-described embodiment, the piezoelectric sheet which is a layer including the active layer included in the actuator unit 21 is stacked in three or five layers, but may be stacked in seven or more layers. The number of individual electrodes and common electrodes may be changed as appropriate according to the number of stacked piezoelectric sheets. In the embodiment described above, the piezoelectric sheet of the inactive layer included in the actuator unit 21 is two layers. However, the piezoelectric sheet may be one layer, or 3 as long as expansion / contraction deformation of the actuator unit 21 is not hindered. It is good also as a layer or more. In the actuator unit 21 of the above-described embodiment, the non-active layer is disposed on the pressure chamber side of the layer including the active layer, but the layer including the active layer is disposed on the pressure chamber 10 side of the non-active layer. The inactive layer may not be provided. However, it can be expected that the displacement efficiency of the actuator unit 21 is further improved by providing the non-active layers 44 and 45 on the pressure chamber 10 side of the layer including the active layer.

  In the above-described embodiment, the common electrode is kept at the ground potential. However, the common electrode is not limited to this as long as the potential is common to the pressure chambers 10.

  In the above-described embodiment, as shown in FIG. 4, the plurality of trapezoidal actuator units 21 are arranged in a staggered pattern in two rows, but the actuator units do not necessarily have to be trapezoidal, The actuator units may be simply arranged in one row along the longitudinal direction of the flow path unit. Alternatively, the actuator units may be arranged in a staggered manner in three or more rows. In addition, one actuator unit 21 may be arranged in each pressure chamber 10 instead of arranging one actuator unit 21 across the plurality of pressure chambers 10.

  The common electrodes 34a and 34b may be formed in large numbers for each pressure chamber 10 so that the projection region in the stacking direction includes the pressure chamber region or the projection region is included in the pressure chamber region. However, it is not always necessary to provide one conductive sheet provided in almost the entire area of one actuator unit 21. However, at this time, it is necessary that the common electrodes are electrically connected so that the portions corresponding to the pressure chambers 10 all have the same potential.

1 is a schematic view of an inkjet printer including an inkjet head according to an embodiment of the present invention. 1 is a perspective view of an inkjet head according to an embodiment of the present invention. It is sectional drawing along the II-II line of FIG. FIG. 3 is a plan view of a head body included in the inkjet head depicted in FIG. 2. It is an enlarged view of the area | region enclosed with the dashed-dotted line drawn by FIG. FIG. 6 is an enlarged view of a region surrounded by an alternate long and short dash line depicted in FIG. 5. FIG. 7 is a partial cross-sectional view of the head body depicted in FIG. 4 taken along line III-III depicted in FIG. 6. FIG. 6 is an enlarged view of a region surrounded by a two-dot chain line drawn in FIG. 5. FIG. 5 is a partially exploded perspective view of the head body depicted in FIG. 4. It is the expanded sectional view which looked at the area | region enclosed with the dashed-dotted line drawn in FIG. 7 from the horizontal direction. It is a schematic diagram which shows one modification of arrangement | positioning of the pressure chamber in a flow-path unit. It is a schematic diagram which shows another modification of arrangement | positioning of the pressure chamber in a flow path unit.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Inkjet head 1a Head main body 3 Ink reservoir 3a, 3b Opening 4 Flow path unit 5 Manifold 5a, 15a Submanifold (common ink passage)
8 Ink ejection port (nozzle)
10 pressure chamber 10x diamond region (parallelogram region)
22, 23, 24, 25, 26, 27, 28, 29, 30 (sheet member)
12 Aperture 21 Actuator unit 22 Cavity plate 30 Nozzle plate 32 Ink flow paths 34a, 34b Common electrodes 35a, 35b Individual electrodes 11a First pressure chamber row 11b Second pressure chamber rows 41-43 Piezoelectric sheets 44, 45 Piezoelectric sheet 50 Flexible printed circuit board (FPC)
101 Inkjet printer R Strip area

Claims (16)

A plurality of nozzles that eject ink;
A plurality of pressure chambers communicating with the nozzle and having a substantially parallelogram-like planar shape are arranged adjacent to each other at equal intervals in the first direction and the second direction intersecting the first direction. A plurality of pressure chamber rows formed by:
A first and second common ink passage that communicates with any of the plurality of pressure chambers and extends in parallel with each other in the first direction so as to straddle the plurality of pressure chamber rows;
A plurality of pressure chambers formed side by side in the second direction,
A first pressure chamber communicating with the first common ink passage at an acute angle portion on one side and a first nozzle at the acute angle portion on the other side; and
A second pressure chamber adjacent to the other side of the first pressure chamber and communicating with the first common ink passage at the acute angle portion on the one side and the second nozzle at the acute angle portion on the other side; ,
A third pressure chamber adjacent to the other side of the second pressure chamber and communicating with the third nozzle at the acute angle portion on the one side and the second common ink passage at the acute angle portion on the other side; ,
A fourth pressure chamber adjacent to the other side of the third pressure chamber and communicating with the fourth nozzle at the acute angle portion on the one side and the second common ink passage at the acute angle portion on the other side; Have
In plan view, the first nozzle, the second nozzle, the third nozzle, and the fourth nozzle are disposed between the first common ink passage and the second common ink passage. An inkjet head characterized by being made. The plurality of pressure chambers and the common ink passage are connected via an aperture;
The inkjet head according to claim 1, wherein the aperture is disposed at a height different from the pressure chamber in a direction orthogonal to the plane and substantially parallel to the plane.   The aperture overlaps with a pressure chamber of a pressure chamber row adjacent to the pressure chamber row arranged in the first direction to which the pressure chamber to which the aperture is connected belongs in a plan view. The inkjet head according to 1 or 2. A first pressure chamber row group and a second pressure chamber row group, each including a plurality of the pressure chamber rows and arranged so as to be overlapped with each other in a direction orthogonal to the first direction. With
In the overlapped portion, the number of pressure chambers included in the pressure chamber row of each of the first pressure chamber row group and the second pressure chamber row group is less than the non-overlapping portion, and The number of pressure chambers included in the pressure chamber row in a portion where the sum of the pressure chambers included in the pressure chamber row in the first pressure chamber row group and the second pressure chamber row group does not overlap. The inkjet head according to any one of claims 1 to 3, wherein The plurality of pressure chamber rows constituting the first pressure chamber row group and the plurality of pressure chamber rows constituting the second pressure chamber row group each fall within a trapezoidal region as viewed from the third direction. And
The first pressure chamber row group and the second pressure chamber row group have a trapezoidal hypotenuse corresponding to the adjacent first pressure chamber row group and the second pressure chamber with respect to a direction orthogonal to the first direction. The trapezoidal hypotenuse corresponding to the row group is alternately arranged in a staggered manner along the first direction,
The ink supplied from the common ink passage is ejected from the nozzle at a position overlapping the trapezoid corresponding to the first pressure chamber row group and the second pressure chamber row group as seen from the third direction. 5. The ink jet head according to claim 1, wherein a trapezoidal actuator unit that generates pressure on the ink in the pressure chamber is disposed. A plurality of nozzles that eject ink;
A plurality of pressure chambers communicating with the nozzle and having a substantially parallelogram-like planar shape are arranged adjacent to each other at equal intervals in the first direction and the second direction intersecting the first direction. A plurality of pressure chamber rows formed by:
A common ink passage that communicates with any one of the plurality of pressure chambers and extends in parallel to each other in the first direction so as to straddle the plurality of pressure chamber rows,
The pressure chamber row formed by a plurality of the pressure chambers arranged in the second direction,
A first pressure chamber communicating with the first nozzle at the acute angle portion on one side and the common ink passage at the acute angle portion on the other side;
A second pressure chamber adjacent to the other side of the first pressure chamber and communicating with the second nozzle on the one side and the common ink passage on the other side;
A third pressure chamber adjacent to the other side of the second pressure chamber and communicating with the common ink passage on the one side and a third nozzle on the other side;
A fourth pressure chamber adjacent to the other side of the third pressure chamber and communicating with the common ink passage on the one side and a fourth nozzle on the other side;
The inkjet head, wherein the common ink passage is disposed between the second nozzle and the third nozzle in a plan view.   The second pressure chamber and the third pressure chamber, which overlap with one common ink passage in a plan view, are overlapped when viewed from the first direction. Inkjet head. The pressure chamber and the common ink passage are connected via an aperture;
The inkjet head according to claim 6, wherein the aperture is disposed at a height different from the pressure chamber in a direction orthogonal to a plane.   The aperture overlaps with a pressure chamber of a pressure chamber row adjacent to the pressure chamber row arranged in the first direction to which the pressure chamber connected to the aperture belongs in a plan view. Item 10. The inkjet head according to any one of Items 6 to 8. A first pressure chamber row group and a second pressure, each including a plurality of the pressure chamber rows, arranged so as to be overlapped with each other in a direction orthogonal to the extending direction of the common ink passage. A group of rooms,
In the overlapped portion, the number of pressure chambers included in the pressure chamber row of each of the first pressure chamber row group and the second pressure chamber row group is less than the non-overlapping portion, and The number of pressure chambers included in the pressure chamber row in a portion where the sum of the pressure chambers included in the pressure chamber row in the first pressure chamber row group and the second pressure chamber row group does not overlap. The inkjet head according to any one of claims 6 to 9, wherein The plurality of pressure chamber rows constituting the first pressure chamber row group and the plurality of pressure chamber rows constituting the second pressure chamber row group each fall within a trapezoidal region as viewed from the third direction. And
The first pressure chamber row group and the second pressure chamber row group have a trapezoidal hypotenuse corresponding to the adjacent first pressure chamber row group and the second pressure chamber with respect to a direction orthogonal to the first direction. The trapezoidal hypotenuse corresponding to the row group is alternately arranged in a staggered manner along the first direction,
The ink supplied from the common ink passage is ejected from the nozzle at a position overlapping the trapezoid corresponding to the first pressure chamber row group and the second pressure chamber row group as seen from the third direction. The ink jet head according to claim 10, wherein a trapezoidal actuator unit that generates pressure on the ink in the pressure chamber is disposed.   The arrangement direction of the pressure chamber rows is the second direction forming an acute angle with the first direction, and adjacent projection lines on a straight line along the first direction of the plurality of nozzles The ink jet head according to claim 1, wherein the ink jet heads are separated by a predetermined distance. A plurality of nozzles that eject ink;
A plurality of common ink passages extending parallel to each other in a first direction;
The one end communicates with the nozzle and the other end communicates with the common ink passage, and has a substantially parallelogram-shaped planar shape with rounded corners, and includes the first direction along the plane. A plurality of pressure chambers arranged adjacent to each other in a dimension;
An actuator unit for generating a pressure on the ink in the pressure chamber in order to discharge the ink supplied from the common ink passage from the nozzle;
A plurality of parallelogram regions having a planar shape substantially similar to the pressure chambers in the plane divided according to the arrangement of the plurality of pressure chambers,
The pressure chambers are included one by one in plan view, and are arranged adjacent to each other in a second direction that forms an acute angle with the first direction so as to share one oblique side with respect to the second direction. A first parallelogram region having a first nozzle at an acute angle portion, and a second parallel region having a second nozzle adjacent to the one side of the first parallelogram region and at an acute angle portion on one side. A quadrilateral region, a third parallelogram region adjacent to the one side of the second parallelogram region and having a third nozzle at an acute angle portion on the other side, and the third parallelogram A parallelogram region group comprising a fourth parallelogram region adjacent to one side of the region and having a fourth nozzle at the acute angle portion on the other side;
When the common ink passage overlaps at least one of the first parallelogram region and the fourth parallelogram region in plan view, and overlaps the first parallelogram region, When the one side wall extending in the first direction is adjacent to the other side of the first nozzle and overlaps the fourth parallelogram region, the side wall extending in the first direction An ink jet head, wherein the other side wall is disposed so as to be close to the one side of the fourth nozzle.   Projection lines on the straight line along the first direction of the first to fourth nozzles do not overlap each other, and the projection line at the first nozzle and the projection line at the third nozzle. The inkjet head according to claim 13, wherein an interval between the projection line and the fourth nozzle is equal to an interval between the projection line of the second nozzle and the projection line of the fourth nozzle. A plurality of the parallelogram regions are arranged in the first direction to form a parallelogram region row;
The plurality of parallelogram region rows are arranged along the second direction,
In the first direction, the width has the same length as the separation distance between the two pressure chambers adjacent to each other in the first direction, and in a direction perpendicular to the first direction so as to cross the actuator unit. In the extended belt-like region, there are one nozzle belonging to each parallelogram region row and adjacent projection lines on the straight line along the first direction of the nozzles. The inkjet heads according to claim 13 or 14, wherein are spaced apart at equal intervals corresponding to the resolution at the time of printing.   An ink jet printer comprising the ink jet head according to claim 1.

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