JP2010042555A - Liquid ejecting head and liquid ejecting head unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress streak-shape irregularities of an image formed by ejection of a liquid. <P>SOLUTION: A head unit has a head set 1 of two inkjet heads 2a and 2b formed in one set. Ejection opening groups 71-74 each with a quadrangular region 83 and triangular regions 81 and 82 are formed on an ink ejection surface of the inkjet head 2. The two inkjet heads 2a and 2b are arranged parallel to each other so that the triangular region 81 of the ejection opening group 71 and the triangular region 82 of the ejection opening group 74 overlap on each other along a sub-scanning direction. A plurality of ejection openings 8 which constitute the overlapped triangular regions 81 and 82 are arranged in a main scanning direction so that the ejection opening 8 of the middle of three ejection openings which belong to the triangular region 82 and are separated from each other by a distance corresponding to 600 dpi is disposed in the middle of two ejection openings 8 which belong to the triangular region 81 and are separated by twice the distance corresponding to 600 dpi with respect to the main scanning direction. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a liquid discharge head that discharges liquid and a liquid discharge head unit.

  Patent Document 1 describes an ink jet head having four nozzle formation regions in which a plurality of nozzles (nozzles constituting discharge ports) are arranged adjacently in a matrix. In this ink-jet head, the four nozzle formation regions all have a trapezoidal plane shape, and the main scan is performed by partially overlapping so that the oblique sides of two adjacent nozzle formation regions are parallel and at the same position in the main scanning direction. It is arranged along the direction. In the overlapping part of two adjacent nozzle formation regions, they are complementary to each other so that the distance in the main scanning direction between the nozzles adjacent in the main scanning direction is a distance corresponding to 600 dpi. For this reason, an ink jet head capable of ejecting ink from the four nozzle formation regions along the main scanning direction is obtained.

JP 2006-256315 A

  Using two inkjet heads described in Patent Document 1 above, these two inkjet heads are aligned in the main scanning direction, and nozzle formation regions located at the ends of two adjacent inkjet heads are arranged in one inkjet head. A head unit in which the print area is elongated along the main scanning direction is configured by overlapping the two adjacent nozzle formation areas. When such a head unit is configured, nozzles adjacent to each other at a distance corresponding to 600 dpi in the main scanning direction at the outermost portion in the sub-scanning direction in the overlapping portion between the nozzle formation regions of two adjacent inkjet heads. The separation distance in the sub-scanning direction (hereinafter referred to as the first nozzles) is much larger along the sub-scanning direction than the overlapping portion between two adjacent nozzle formation regions in one inkjet head. When such a head unit is assembled to the apparatus main body in a state of being slightly inclined with respect to the main scanning direction, the distance between the first nozzles in the main scanning direction becomes significantly larger than the distance corresponding to 600 dpi. As a result, streaky unevenness, that is, white streaks, is formed in the image formed by the ink ejected from the ink jet head.

  On the other hand, even in the overlap portion of two adjacent nozzle formation regions of one inkjet head, the nozzles that are on the outermost side in the sub-scanning direction and are adjacent to each other at a distance corresponding to 600 dpi in the main scanning direction (hereinafter referred to as the second nozzle). Are spaced apart from each other in the sub-scanning direction in one nozzle formation region and are adjacent to each other at a distance corresponding to 600 dpi in the main scanning direction (hereinafter referred to as third nozzles). Larger than When such an ink-jet head is also assembled to the apparatus main body with a slight inclination with respect to the main scanning direction, the distance between the second nozzles in the main scanning direction is equivalent to 600 dpi and the main scanning between the third nozzles. Greater than the distance in the direction. As a result, stripe-shaped unevenness, that is, white stripes, may be formed in the image formed by the ink ejected from the inkjet head.

  Therefore, an object of the present invention is to provide a liquid discharge head and a liquid discharge head unit that suppress streaky unevenness.

  The liquid discharge head of the present invention has a discharge surface elongated in one direction in which a plurality of discharge ports for discharging liquid are formed, and the plurality of discharge ports are predetermined along the one direction on the discharge surface. A liquid ejection head comprising a plurality of ejection port arrays each arranged at intervals, and a plurality of ejection port groups in which the plurality of ejection port arrays are arranged adjacent to each other in a direction orthogonal to the one direction. The discharge port group includes a first region in which a plurality of discharge ports are arranged at a predetermined distance in the one direction, and a plurality of discharge ports arranged in the one direction and adjacent to the one direction. The discharge port includes a second region having a portion separated by twice the predetermined distance, and the second region of one discharge port group is separated from the other in the orthogonal direction. The plurality of discharges so as to overlap the second region of the discharge port group Group is located. Then, the two discharge ports forming the two overlapping second regions constitute the two discharge ports forming a part separated by twice the predetermined distance belonging to the one discharge port group in the one direction. Two outlets that are separated by the predetermined distance in the one direction belonging to the second region of the another outlet group are arranged between the outlets, and only twice the predetermined distance that belongs to the different outlet group. The one discharge port is disposed so that the two discharge ports separated by the predetermined distance in the one direction belonging to the second region of the one discharge port group are arranged between the two discharge ports constituting the separated part. It is lined up in the direction.

  In another aspect, the liquid discharge head of the present invention has a discharge surface that is long in one direction in which a plurality of discharge ports for discharging a liquid are formed, and the plurality of discharge ports are the one on the discharge surface. A plurality of discharge port arrays each arranged at a predetermined interval along the direction, and a plurality of discharge port groups in which the plurality of discharge port arrays are arranged adjacent to each other in a direction orthogonal to the one direction In the liquid discharge head, the discharge port group includes a first region in which the plurality of discharge ports are arranged at a predetermined distance in the one direction, and a plurality of the discharge ports are arranged in the one direction. The two discharge ports adjacent to each other have a second region having a portion separated by twice the predetermined distance, and the second region of one discharge port group extends along the orthogonal direction. And so as to overlap the second region of the other outlet group, Serial plurality of discharge port groups are arranged. Then, the two discharge ports forming the two overlapping second regions constitute the two discharge ports forming a part separated by twice the predetermined distance belonging to the one discharge port group in the one direction. Between the outlets, at least the middle of the three outlets separated by the predetermined distance in the one direction belonging to the second region of the different outlet group is disposed, and the different outlet group The three outlets separated by the predetermined distance in the one direction belonging to the second region of the one outlet group between the two outlets constituting the part separated by twice the predetermined distance belonging to Are arranged in the one direction so that at least the middle outlet is disposed.

  According to this, even if the liquid ejection head is not aligned with high accuracy, the liquid ejected from the ejection ports belonging to the two second regions in which one ejection port group and another ejection port group overlap each other. It is possible to suppress the occurrence of streaky unevenness in the formed image.

  In the present invention, it is preferable that the discharge port in the middle is disposed in the middle of the two discharge ports constituting a portion separated by twice the predetermined distance in the one direction. Thereby, it is possible to further suppress the occurrence of streak-like unevenness.

  The liquid discharge head unit of the present invention has a discharge surface that is long in one direction in which a plurality of discharge ports for discharging liquid are formed, and the plurality of discharge ports are along the one direction on the discharge surface. A plurality of liquid discharges comprising a plurality of discharge port arrays each arranged at a predetermined interval and a discharge port group in which the plurality of discharge port arrays are arranged adjacent to each other in a direction orthogonal to the one direction. It has a head. The discharge port group includes a first region in which a plurality of discharge ports are arranged at a predetermined distance in the one direction, and a plurality of discharge ports arranged in the one direction and adjacent to the one direction. The discharge port has a second region having a portion separated by twice the predetermined distance, and the second region of one liquid discharge head is separated from the other in the orthogonal direction. The plurality of liquid ejection heads are arranged in parallel with each other so as to overlap the second region of the liquid ejection head, and the plurality of ejection ports constituting the two overlapping second regions are related to the one direction. , The predetermined distance in the one direction belonging to the second region of the other liquid discharge head between the two discharge ports constituting the portion of the one liquid discharge head separated by twice the predetermined distance. The two outlets are arranged And the predetermined distance in the one direction belonging to the second region of the one liquid discharge head between the two discharge ports constituting the part of the another liquid discharge head separated by twice the predetermined distance. The two discharge ports are arranged in the one direction so as to be arranged.

  In another aspect, the liquid discharge head unit of the present invention has a discharge surface that is elongated in one direction in which a plurality of discharge ports for discharging a liquid are formed, and the plurality of discharge ports are the above-described discharge ports. A plurality of discharge port arrays each arranged at a predetermined interval along one direction and a discharge port group in which the plurality of discharge port arrays are arranged adjacent to each other in a direction orthogonal to the one direction are configured. And a plurality of liquid discharge heads. The discharge port group includes a first region in which a plurality of discharge ports are arranged at a predetermined distance in the one direction, and a plurality of discharge ports arranged in the one direction and adjacent to the one direction. The discharge port has a second region having a portion separated by twice the predetermined distance, and the second region of one liquid discharge head is separated from the other in the orthogonal direction. The plurality of liquid ejection heads are arranged in parallel with each other so as to overlap the second region of the liquid ejection head, and the plurality of ejection ports constituting the two overlapping second regions are related to the one direction. , The predetermined distance in the one direction belonging to the second region of the other liquid discharge head between the two discharge ports constituting the portion of the one liquid discharge head separated by twice the predetermined distance. Of the three outlets The second region of the one liquid discharge head is disposed between the two discharge ports, which are disposed at least in the middle and constitute a portion separated by twice the predetermined distance of the other liquid discharge head Are arranged in the one direction such that at least the middle of the three outlets that are separated by the predetermined distance in the one direction belongs to each other.

  According to this, even if a head unit formed by combining a plurality of liquid discharge heads is not accurately aligned, the head unit is formed by liquid discharged from the discharge ports belonging to the two second regions that overlap each other. It is possible to suppress the occurrence of streak-like unevenness in the printed image.

  In the present invention, it is preferable that the discharge port in the middle is disposed in the middle of the two discharge ports constituting a portion separated by twice the predetermined distance in the one direction. Thereby, it is possible to further suppress the occurrence of streak-like unevenness.

  According to the liquid ejection head of the present invention, even if the liquid ejection head is not aligned with high accuracy, the ejection ports belonging to the two second regions in which one ejection port group and another ejection port group overlap each other. It is possible to suppress the occurrence of streak-like unevenness in the image formed by the discharged liquid.

  According to the liquid discharge head unit of the present invention, when a head unit having a long print area is configured by combining a plurality of liquid discharge heads, one liquid discharge head and another liquid discharge head are positioned with high accuracy. Even if they are not aligned, it is possible to suppress the occurrence of streak-like unevenness in the image formed by the liquid ejected from the ejection ports belonging to the two second regions where the heads overlap each other.

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

  FIG. 1 is a schematic cross-sectional view of an ink jet printer having a head unit according to a first embodiment of the present invention. FIG. 2 is a plan view of the head unit shown in FIG.

  As shown in FIG. 1, the inkjet printer 100 is a color inkjet printer that ejects four colors of ink from a plurality of inkjet heads 2. The ink jet printer 1 includes a paper feed mechanism 111 on the left side in FIG. 1 and a paper discharge unit 112 on the right side in FIG. 1. A head unit 5 having an inkjet head 2 is provided.

  Inside the inkjet printer 100, a paper transport path is formed through which a paper as a recording medium is transported from the paper feed mechanism 111 toward the paper discharge unit 112. The paper feed mechanism 111 is provided with a pickup roller 122 that sends out the uppermost sheet among a plurality of sheets stored in the sheet tray 121. The sheet is fed from the left to the right in FIG.

  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. A pressing roller 105 is disposed immediately downstream of the sheet feeding mechanism 111 at a position facing the conveying belt 108, and presses the sheet fed from the sheet feeding mechanism 111 against the conveying surface 108 a of the conveying belt 108. .

  The outer peripheral surface of the conveyance belt 108, that is, the conveyance surface 108a is subjected to silicone treatment and has adhesiveness. As a result, the sheet pressed against the conveyance surface 108a is conveyed toward the downstream side while being held by the adhesive force of the conveyance surface 108a. At this time, the belt roller 106 on the downstream side in the paper transport direction is applied with a driving force from a driving motor (not shown) and is rotated clockwise (in the direction of arrow A) in FIG.

  In the middle part of the paper transport path, the area facing the head unit 5 is an image forming area where an image is formed on the paper. Further, a peeling member 113 is provided immediately downstream of the conveying belt 108 along the sheet conveying path. The peeling member 113 is configured to peel the paper held on the conveyance surface 108 a of the conveyance belt 108 from the conveyance surface 108 a and send it to the right paper discharge unit 112.

  In a region surrounded by the conveyor belt 108, a substantially rectangular parallelepiped platen 109 is disposed at a position facing the inkjet head 2. The platen 109 supports the platen 109 from the inner peripheral side by making contact with the lower surface of the conveying belt 108 on the upper side.

  As shown in FIGS. 1 and 2, the head unit 5 includes eight inkjet heads 2 and a support member 4 that supports the eight inkjet heads 2. The eight inkjet heads 2 are arranged in a staggered pattern along the sub-scanning direction parallel to the paper transport direction B (the direction of arrow B in FIG. 1). The eight inkjet heads 2 constitute one head set 1 for every two adjacent inkjet heads 2a and 2b, and the head unit 5 has a total of four head sets 1. The two inkjet heads 2a and 2b constituting each head set 1 are effective print area lengths obtained by adding the print area lengths in the main scanning direction (direction perpendicular to the paper transport direction B: one direction) to the main scanning direction. Are fixed to the support member 4 in parallel to each other so that the maximum print width of the paper is slightly longer than this. The four head sets 1 eject four different colors of ink (magenta, yellow, cyan, black) for each set.

  As shown in FIGS. 1 and 2, each inkjet head 2 has an elongated rectangular parallelepiped shape whose longitudinal direction extends in the main scanning direction. Further, as shown in FIG. 1, a head main body 3 is provided at the lower end of the inkjet head 2. A reservoir unit 6 for temporarily storing ink supplied from an ink supply source (not shown) and supplying the stored ink to the head body 3 is fixed to the upper surface of the head body 3. The reservoir unit 6 has a head fixing portion 6a formed longer than the head body 3 in the main scanning direction. As shown in FIG. 2, the head fixing portion 6a is formed to extend on both sides in the longitudinal direction of the head body 3 (that is, both sides in the main scanning direction), and is fixed to the support member 4 with screws (not shown). Yes.

  The support member 4 is formed with an opening (not shown) that is open corresponding to the arrangement position of each inkjet head 2. The lower surface of the head body 3 (the ink ejection surface 3a on which the plurality of ejection ports 8 are formed) is exposed from the opening. With such a configuration, when the paper transported by the transport belt 108 passes immediately below the head main body 3, ink droplets of each color are sequentially applied from the ejection port 8 (see FIG. 5) toward the top surface of the paper. By discharging, a desired color image is formed on the paper.

  Next, details of the head body 3 will be described. FIG. 3 is a plan view of the head main body 3 shown in FIG. As shown in FIG. 3, the head body 3 includes a flow path unit 7 in which an ink flow path is formed, and four actuator units 21 bonded to the upper surface of the flow path unit 7. The flow path unit 7 has a rectangular planar shape extending in the main scanning direction. In FIG. 3, a manifold channel 55 that is a common ink chamber provided in the channel unit 7 is drawn with a broken line. Ink from the reservoir unit 6 is supplied to the manifold channel 55 through the plurality of openings 55b. The manifold channel 55 is branched into a plurality of sub-manifold channels 55 a extending in parallel with the longitudinal direction of the channel unit 7. Four sub-manifold channels 55 a extend in parallel with the longitudinal direction of the channel unit 7 in a region overlapping each actuator unit 21. A large number of individual ink flow paths 32 (described later) communicating with each of the ejection ports 8 (see FIGS. 4 and 8) are connected to each sub-manifold flow path 55a.

  Four actuator units 21 having a trapezoidal planar shape are bonded to the upper surface of the flow path unit 7. The four actuator units 21 are arranged in a staggered pattern along the main scanning direction so as to avoid the openings 55b. 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 7. The plurality of openings 55 b are arranged in two rows along the longitudinal direction of the flow path unit 7, and five openings in each row, a total of ten openings 55 b are provided at positions that do not interfere with the actuator unit 21. Further, the oblique sides of the adjacent actuator units 21 partially overlap in the width direction (sub-scanning direction) of the flow path unit 7.

  In the ink ejection surface 3a, which is the lower surface of the flow path unit 7, the area facing the adhesion area of the actuator unit 21 is an ink ejection area in which a large number of ejection ports 8 are arranged in a matrix. A pressure chamber group 9 in which a large number of pressure chambers 10 (see FIG. 4) are arranged in a matrix is formed on the upper surface of the flow path unit 7 to which the actuator unit 21 is bonded. At this time, the actuator unit 21 has a size and shape straddling a number of pressure chambers 10 constituting the pressure chamber group 9.

  FIG. 4 is an enlarged view of a region surrounded by an alternate long and short dash line shown in FIG. As shown in FIG. 4, each of the pressure chambers 10 belonging to the pressure chamber group 9 communicates with the discharge port 8 at one end of the longer diagonal line, and the sub-manifold channel 55a via the aperture 12 at the other end. It is communicated to. In FIG. 4, in order to make the drawing easy to understand, the discharge port 8, the pressure chamber 10, the aperture 12, and the like that are to be drawn with broken lines in the flow path unit 7 are drawn with solid lines.

  The pressure chambers 10 are adjacently arranged in a matrix in a staggered arrangement pattern in two directions, the main scanning direction and the direction C. The shorter diagonal line of the pressure chamber 10 is parallel to the main scanning direction. The direction parallel to one oblique side of the pressure chamber 10 is an obtuse angle θ between the main scanning direction and the direction C. Both acute angle portions of the pressure chamber 10 are located between two adjacent pressure chambers.

  The pressure chambers 10 arranged adjacent to each other form a plurality of pressure chamber rows 11 extending along one direction, and are separated by a distance (677.3 μm) corresponding to 37.5 dpi along each main scanning direction. ing. Further, 16 pressure chambers 10 are arranged in the direction C in a region facing one actuator unit 21. That is, a plurality of pressure chamber rows 11 are arranged in parallel with each other in a direction crossing one direction.

  The pressure chamber row 11 is viewed from the direction perpendicular to the paper surface of FIG. 3 pressure chamber rows 11c and a fourth pressure chamber row 11d. Each of the first to fourth pressure chamber rows 11a to 11d is periodically arranged in the order of 11c → 11d → 11a → 11b → 11c → 11d → ... → 11b from the upper side to the lower side of the actuator unit 21. Is arranged.

  In the pressure chamber 10a constituting the first pressure chamber row 11a and the pressure chamber 10b constituting the second pressure chamber row 11b, the discharge port 8 is connected to the sub-manifold as viewed from the direction perpendicular to the paper surface of FIG. The flow path 55a is unevenly distributed on the lower side of the drawing. And the discharge outlet 8 is connected to the lower end part vicinity of the corresponding pressure chamber 10, respectively.

  On the other hand, in the pressure chamber 10c constituting the third pressure chamber row 11c and the pressure chamber 10d constituting the fourth pressure chamber row 11d, the discharge port 8 is seen from the direction perpendicular to the paper surface of FIG. The sub manifold channel 55a is unevenly distributed on the upper side of the drawing. The discharge port 8 communicates with the vicinity of the upper end portion of the corresponding pressure chamber 10.

  Thus, in the ink ejection region, the ejection ports 8 are arranged so that the positional relationship with respect to the pressure chamber 10 is different between the upper side and the lower side across the sub manifold channel 55a in the sub scanning direction.

  Next, the cross-sectional structure of the head body 3 will be described. FIG. 5 is a cross-sectional view (cross-sectional view showing individual ink flow paths) taken along line V-V in FIG. 4. As can be seen from FIG. 5, each discharge port 8 communicates with the sub-manifold channel 55 a via the pressure chamber 10 and the aperture, that is, the throttle 12. In this manner, the head main body 3 is formed with the individual ink flow path 32 from the outlet of the sub manifold flow path 55 a to the ejection port 8 through the aperture 12 and the pressure chamber 10 for each pressure chamber 10.

  In the present embodiment, the individual ink flow path 32 temporarily extends upward from the sub-manifold flow path 55 a and reaches one end of the pressure chamber 10 formed on the upper surface of the flow path unit 7. Furthermore, the individual ink flow path 32 is obliquely downward from the other end of the pressure chamber 10 extending horizontally, and is connected to the ejection port 8 formed on the lower surface of the flow path unit 7 (that is, the ink ejection surface 3a). ing. As a whole, each individual ink flow path 32 has an arcuate shape with the pressure chamber 10 at the top. Thereby, a smooth flow of ink is realized.

  As can be seen from FIG. 5, the head body 3 is a laminated structure including an upper actuator unit 21 and a lower flow path unit 7. Furthermore, the flow path unit 7 and the actuator unit 21 are each configured as a laminated body of a plurality of thin plates (sheet materials).

  The configuration of the actuator unit 21 will be described. A large number of individual electrodes 35 are arranged in a matrix on the actuator unit 21 in the same pattern as the pressure chamber 10. Each individual electrode 35 is disposed at a position facing the pressure chamber 10 in plan view.

  FIG. 6 is a plan view of the individual electrode 35. As shown in FIG. 6, the individual electrode 35 is composed of two regions, a main electrode region 35a and an auxiliary electrode region 35b. The main electrode region 35a is disposed at a position facing the pressure chamber 10, and is accommodated in the pressure chamber 10 in plan view. The auxiliary electrode region 35b is disposed outside the pressure chamber and is also connected to the main electrode region 35a. Each individual electrode 35 has a thickness of approximately 1 μm.

  7 is a cross-sectional view taken along line VII-VII in FIG. As shown in FIG. 7, the actuator unit 21 includes four piezoelectric sheets 41, 42, 43, and 44 that have substantially the same thickness. These piezoelectric sheets 41 to 44 are disposed across a number of pressure chambers 10 formed in one ink ejection region in the head body 3. The piezoelectric sheets 41 to 44 are made of a lead zirconate titanate (PZT) ceramic material having ferroelectricity.

  As shown in FIG. 6, the main electrode region 35 a of the individual electrode 35 formed on the uppermost piezoelectric sheet 41 has a substantially rhombic planar shape that is substantially similar to the pressure chamber 10. A circular land portion 36 electrically connected to the individual electrode 35 is provided at the tip of the auxiliary electrode region 35b. The land portion 36 is made of, for example, gold containing glass frit, and is electrically joined to a contact provided on a wiring board (not shown).

  As shown in FIG. 7, a common electrode 34 having the same outer shape and a thickness of about 2 μm is interposed between the uppermost piezoelectric sheet 41 and the lower piezoelectric sheet 42. The common electrode 34 is grounded via a wiring board in a region (not shown) on the piezoelectric sheet 41, and is kept at an equal and constant potential in the region corresponding to all the pressure chambers 10, in this embodiment, the ground potential. ing. Both the individual electrode 35 and the common electrode 34 are made of, for example, a metal material such as an Ag—Pd system.

  In the flow path unit 7, as shown in FIG. 5, a total of nine sheets including a cavity plate 22, a base plate 23, an aperture plate 24, a supply plate 25, manifold plates 26, 27, 28, a cover plate 29 and a nozzle plate 30. The materials are stacked.

  The cavity plate 22 is a metal plate in which a large number of approximately diamond-shaped holes (holes with rounded corners) forming the gap of the pressure chamber 10 are provided within the pasting range of the actuator unit 21. The base plate 23 is a metal plate in which a communication hole between the pressure chamber 10 and the aperture 12 and a communication hole from the pressure chamber 10 to the discharge port 8 are provided for one pressure chamber 10 of the cavity plate 22.

  The aperture plate 24 is a metal plate in which a communication hole from the pressure chamber 10 to the discharge port 8 is provided in addition to the hole serving as 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 channel 55a and a communication hole from the pressure chamber 10 to the discharge port 8 for 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 discharge port 8 for one pressure chamber 10 of the cavity plate 22 in addition to the sub-manifold channel 55 a. The cover plate 29 is a metal plate provided with a communication hole from the pressure chamber 10 to the discharge port 8 for each pressure chamber 10 of the cavity plate 22. The nozzle plate 30 is a metal plate provided with a plurality of nozzles for forming the discharge ports 8. One discharge port 8 of the nozzle plate 30 is provided for each pressure chamber 10 of the cavity plate 22. These ten sheets 21 to 30 are stacked in alignment with each other so that the individual ink flow paths 32 as shown in FIG. 5 are formed.

  As is clear from FIG. 5, the pressure chamber 10 and the aperture 12 are provided at different levels in the stacking direction of the plates. The aperture 12 is provided at a position deeper than the pressure chamber 10 through the base plate 23. Thereby, as shown in FIG. 4, the aperture 12 communicating with one pressure chamber 10 can be disposed at a position overlapping with another pressure chamber 10 adjacent to the pressure chamber in plan view. As a result, the pressure chambers 10 are in close contact with each other and are arranged at a higher density, so that high-resolution image printing is realized by the inkjet head 1 having a relatively small occupation area.

  FIG. 8 is a plan view (a plan view of the ink ejection surface 3a) when the head body 3 of one head set 1 is viewed from below. FIG. 9 is an enlarged plan view of a region E surrounded by a two-dot chain line shown in FIG. As shown in FIG. 8, in each ink discharge region, a plurality of discharge ports 8 are arranged adjacent to each other in a matrix, and four discharge port groups 71 to 74 are formed. Here, when the point 60 is virtually assumed at the center of the ink ejection surface 3 a, the four ejection port groups 71 to 74 and all the ejection ports 8 constituting these are arranged symmetrically with respect to the point 60.

  The four discharge port groups 71 to 74 are arranged in a staggered manner in the main scanning direction corresponding to the actuator unit 21. The four discharge port groups 71 to 74 have a trapezoidal planar shape and are arranged so that their parallel opposing sides are along the longitudinal direction (main scanning direction) of the flow path unit 7.

  As shown in FIG. 8, each of the discharge port groups 71 to 74 can be divided into three regions, and one rectangular region (first region) 83 and two triangular regions (second regions) sandwiching it from both sides. ) 81 and 82. The rectangular area 83 shares sides along the sub-scanning direction of the triangular areas 81 and 82. The plurality of ejection ports 8 included in the rectangular region 83 are arranged at a predetermined distance in the main scanning direction, and the center-to-center distance is exactly 42.3 μm (a distance corresponding to 600 dpi). In addition, the plurality of discharge ports 8 included in the triangular regions 81 and 82 are disturbed in such regularity, but are similarly arranged apart in the main scanning direction.

  In each ink ejection surface 3a, adjacent triangular regions 81 and 82 are arranged so as to overlap almost the entire region in the sub-scanning direction.

  The 16 discharge port arrays 75 constituting each of the discharge port groups 71 to 74 are arranged in parallel to each other. The plurality of discharge ports 8 constituting each discharge port array 75 are arranged with their centers separated by 677.3 μm (a distance corresponding to 37.5 dpi) along the main scanning direction, similarly to the arrangement of the pressure chambers 10. It is out.

  Each discharge port array 75 is arranged avoiding each sub-manifold channel 55a (see FIG. 4), and two discharge port columns 75 are associated with one sub-manifold channel 55a on each side. It has been. In these discharge port arrays 75, the number of discharge ports constituting each discharge port array 75 gradually decreases from the long side to the short side of each of the discharge port groups 71 to 74.

  FIGS. 4 and 9 show a band-like region S having a width corresponding to 37.5 dpi in the main scanning direction and extending in the sub-scanning direction in the rectangular region 83. The belt-like region S includes 16 discharge ports 8 regardless of the rectangular region 83 of any of the discharge port groups 71 to 74. These 16 discharge ports 8 all belong to different discharge port arrays 75. When the 16 discharge ports 8 are projected onto a straight line extending in the main scanning direction, the projected points are arranged at equal intervals of 42.3 μm (a distance corresponding to 600 dpi) on the straight line.

  Note that the projection point obtained by projecting the ejection port 8 onto a straight line extending in the main scanning direction is, for example, a straight line (b) parallel to the sub scanning direction and passing through the center of the ejection port 8 as shown in FIG. It is an intersection with a straight line (A) extending in the scanning direction.

  When 16 discharge ports 8 are projected as described above in one belt-like region S, the discharge port 8 projected to the leftmost on the straight line is denoted as (1). In addition, the discharge port 8 projected to a point away from the projection point of (1) in the right direction is described as (2) to (16) in the order from the projection point of (1). At this time, the 16 discharge ports 8 are (1), (9), (13), (15), (5), (7), (11), ( 16), (3), (8), (12), (14), (4), (6), (10), and (2). The 16 discharge port rows 75 belonging to each of the discharge port groups 71 to 74 are arranged in order from the top to the bottom in FIG. 9, the first discharge port row 75a, the second discharge port row 75b. In the case of the discharge port array 75p, the discharge port (1) belongs to the discharge port array 75a, and the discharge port (9) belongs to the adjacent discharge port array 75b.

  As described above, when attention is paid to one ejection port 8 in one band-shaped region S, the two ejection ports 8 arranged on both sides of the ejection port 8 in the main scanning direction are both upward or downward in the sub-scanning direction. Located in one of the. Further, the target discharge port 8 and the two discharge ports 8 are arranged via at least one or more discharge ports 8 (discharge port array 75) in the sub-scanning direction. Further, the 16 discharge ports 8 are arranged in a zigzag shape in the main scanning direction.

  The discharge port groups 71 to 74 occupy a trapezoidal area, and overlap along the sub-scanning direction so that the hypotenuses of two adjacent trapezoids are parallel and at the same position in the main scanning direction. Specifically, the triangular region 82 of the discharge port group 71 and the triangular region 81 of the discharge port group 72, the triangular region 82 of the discharge port group 72 and the triangular region 81 of the discharge port group 73, and the triangular region of the discharge port group 73 82 and the triangular area 81 of the discharge port group 74 overlap substantially over the entire area along the sub-scanning direction.

  In this way, by overlapping the adjacent triangular areas 81 and 82 in the sub-scanning direction, the arrangement of the ejection ports 8 in the overlapping area has a complementary relationship, and printing can be performed without interruption even across the ejection port groups. This is to make it possible. At this time, in the overlapping triangular areas 81 and 82, assuming a band-like area R similar to the quadrangular area 83, the discharge ports 8 in the band-shaped area R are relatively similar to the discharge ports 8 in the quadrangular area 83. There is a positional relationship, and all the ejection ports 8 are arranged at equal intervals corresponding to the printing resolution in the main scanning direction.

  Here, the details of the complementary relationship between the triangular regions 81 and 82 belonging to the different discharge port groups 71 to 74 will be described. FIG. 10 is a diagram showing projected points projected from the respective ejection ports 8 on a straight line extending in the main scanning direction in the overlapping region of the ejection port groups and in the vicinity thereof. In FIG. 10, white circles are projection points from the discharge ports 8 belonging to the triangular area 81, and black circles are projection points from the discharge ports 8 belonging to the triangular area 82.

  9 shows a plurality of strip-like regions R1 to R8 extending in the sub-scanning direction in a region where the triangular region 81 of the ejection port group 73 of the inkjet head 2 and the triangular region 82 of the ejection port group 72 overlap. Has been. Each of the strip regions R1 to R8 has a width (677.3 μm) corresponding to 37.5 dpi in the main scanning direction. Each strip region R1 to R8 includes a total of 16 discharge ports 8 including at least one or more discharge ports 8 belonging to the triangular regions 81 and 82, respectively. These 16 discharge ports 8 all belong to different discharge port arrays 75.

  Further, when only the white circles are seen, as shown in FIG. 10, there are a plurality of portions separated by twice the distance corresponding to 600 dpi along the main scanning direction in the strip regions R1 to R4, and in the strip regions R5 to R8, In addition to twice the distance corresponding to 600 dpi, there are a plurality of portions separated by 3 times and 7 times. The black circles are arranged in a pattern opposite to the white circles described above.

  However, all the projection points of the discharge ports 8 included in the eight belt-like regions R1 to R8 are aligned on the straight line at equal intervals corresponding to the printing resolution. For this reason, it becomes possible to print without interruption over almost the entire length of one inkjet head 2 in the main scanning direction. Specifically, with respect to the main scanning direction, a length obtained by subtracting the widths of the triangular region 81 of the outermost discharge port group 71 and the triangular region 82 of the discharge port group 74 from the entire width of the four discharge port groups 71 to 74. be equivalent to.

  In the present embodiment, as described above, two inkjet heads 2 are arranged in parallel to form one head set 1. In the connection area where the two inkjet heads 2 are connected, one triangle area overlaps the other triangle area and the quadrilateral area that follows.

  Here, the detail of the structure in the above-mentioned connection area | region is demonstrated using FIG.11 and FIG.12. FIG. 11 is an enlarged plan view of a region F surrounded by a two-dot chain line shown in FIG. In FIG. 11, for easy understanding of the drawing, the ejection port group 71 of one inkjet head 2a and the ejection port group 74 of the other inkjet head 2b are drawn close to the sub-scanning direction. FIG. 12 is a diagram illustrating an arrangement state of projection points created by the discharge ports 8 in the connection region.

  In FIG. 12, the white circles are the ejection ports 8 belonging to the triangular area 81 and the quadrangular area 83 of one inkjet head 2a, and the ejection ports 8 belonging to the triangular area 82 of the other inkjet head 2b are in the sub-scanning direction. This is a point projected from the discharge port 8 that does not overlap along. A white triangle is a point projected from the discharge port 8 belonging to the triangular region 81 of the inkjet head 2a and overlapping the discharge port 8 belonging to the triangular region 82 of the inkjet head 2b along the sub-scanning direction. . The black circles are projected from the ejection ports 8 belonging to the triangular region 82 and the rectangular region 83 of the inkjet head 2b and not overlapping the ejection ports 8 belonging to the triangular region 81 of the inkjet head 2a along the sub-scanning direction. Is a point. The black triangle belongs to the ejection port 8 belonging to the triangular region 81 of one inkjet head 2a that overlaps the ejection port 8 belonging to the rectangular region 83 of the inkjet head 2b along the sub-scanning direction, and to the rectangular region 83 of the inkjet head 2a. This is a point projected from the ejection port 8 belonging to the triangular area 82 of the other inkjet head 2b overlapping the ejection port 8 along the sub-scanning direction.

  In the present embodiment, in the connected region, one triangular region 81 is arranged close to the other triangular region 82 along the main scanning direction by 65 times the distance corresponding to 600 dpi.

  FIG. 11 shows four belt-like regions T1 to T4 virtually imagined in regions 85 and 86 in which triangular regions 81 and 82 overlap in the sub-scanning direction in the connected region. Each of the belt-like regions T1 to T4 extends in the sub scanning direction and has a width (677.3 μm) corresponding to 37.5 dpi in the main scanning direction. Each of the strip-like regions T1 to T4 includes a total of 16 or more ejection ports 8 belonging to the regions 85 and 86. However, the centers of the ejection ports 8 that overlap in the sub-scanning direction are not shifted in the main scanning direction. Further, the 16 or more discharge ports 8 in each of the belt-like regions T1 to T4 all belong to different discharge port arrays 75.

  As shown in FIG. 12, the centers of all the ejection ports 8 belonging to the overlapping regions 85 and 86 are arranged at a distance corresponding to 600 dpi in the main scanning direction. For this reason, it becomes possible to print without interruption over almost the entire length of the single head set 1 in the main scanning direction. The net width that can be printed without interruption is the triangular area 81 and the discharge port group 74 of the discharge port group 71 located on the outermost side from the full width of the eight discharge port groups 71 to 74 belonging to the head set 1 in the main scanning direction. Is equal to the triangular area 82 and the length obtained by subtracting 65 times the distance corresponding to 600 dpi.

  As described above, in the present embodiment, the four belt-like regions T1 to T4 are virtually assumed in the overlapping region of the two inkjet heads 2a and 2b as described above. The arrangement form of the projection points in these areas corresponds to the form in which the band-like areas R5 to R8 are superimposed on the band-like areas R1 to R4 shown in FIG. Specifically, it is the same as the form in which the central black circle overlaps among the three leftmost black circles in the strip region R5 at the position of the leftmost black circle in the strip region R1. On both sides of the black circle and the white circle in the main scanning direction of each of the belt-like regions T1 to T4, either a white triangle or a black triangle in which the ejection ports of the two inkjet heads 2a and 2b overlap in the sub-scanning direction exists.

  That is, with respect to the main scanning direction, the discharge ports 8 belonging to the region 86 are located in the middle of the two discharge ports 8 constituting a portion where the distance between the centers of the discharge ports 8 belonging to the region 85 is twice the distance corresponding to 600 dpi. Among the three outlets separated by a distance corresponding to a center distance of 600 dpi, an outlet 8 in the middle is arranged. Further, the two ejection ports 8 on both sides in the main scanning direction overlap the two ejection ports 8 belonging to the region 85 in the sub scanning direction. Note that the discontinuous portion of the discharge port 8 belonging to the region 86 is also complemented by the discharge port of the region 85 in the same manner as described above.

  As described above, the middle discharge port 8 among the three consecutive discharge ports 8 in one overlap region is arranged in the middle of the two discharge ports 8 in the other overlap region. When the head assembly 1 is assembled to the apparatus main body, even if the head assembly 1 is slightly tilted with respect to the main scanning direction, it is possible to suppress a decrease in image quality. This will be described below with reference to FIG. FIG. 13 is a diagram showing the position of the projection point when the head set is slightly tilted with respect to the main scanning direction. Projection point P1 is a projection point from discharge port 8 in the middle of three consecutive discharge ports 8 in one overlapping region, and projection point P3 is from discharge port 8 adjacent to intermediate discharge port 8. Is the projection point. On the other hand, the projection point P2 is a projection point from the two discharge ports 8 in the other region.

  As shown in FIG. 13 (a), even if the projection point P1 is shifted to a position that exactly overlaps one of the two projection points P2 due to the inclination when the head set 1 is assembled to the apparatus main body, the projection point P3 is not changed. It is arranged in the middle of the two projected points P2. For this reason, it is difficult to form a portion where the distance between the projection points in the main scanning direction is larger than the distance corresponding to 600 dpi between the projection points P2. Further, as shown in FIG. 13B, even if the projection point P1 is shifted so as to approach one of the two projection points P2, the projection point P3 is arranged between the two projection points P2. This also makes it difficult to form a portion where the distance between the projection points in the main scanning direction is larger than the distance corresponding to 600 dpi between the projection points P2. As a result, even if the head group 1 is not aligned with high accuracy, white streaks are not formed in the image formed by the ink ejected from the ejection ports 8 belonging to the head group 1, and deterioration in image quality is suppressed. can do. It should be noted that when the head unit 5 is assembled to the apparatus main body, the same effect can be obtained even if the head unit 5 is displaced with respect to the apparatus main body.

  Further, a band-like area U similar to the band-like area S is assumed in the area where the triangular areas 81 and 82 and the quadrangular area 83 of the connection area overlap. The belt-like region U also includes a total of 16 or more ejection ports, but the centers of the ejection ports that overlap each other in the sub-scanning direction are not displaced with respect to the main scanning direction. One strip-shaped region U includes 16 discharge ports 8 belonging to the rectangular region 83. Therefore, when the head group 1 or the head unit 5 is assembled to the apparatus main body, even if the head group 1 or the head unit 5 is slightly inclined with respect to the main scanning direction, ink is ejected from the ejection ports 8 belonging to the rectangular region 83. As a result, no white streaks appear in the image.

  In the head set 1 configured as described above, when the actuator unit 21 is appropriately driven in accordance with the conveyance of the paper, an image having a resolution of 600 dpi with the print width of the two inkjet heads 2 in the main scanning direction can be formed. it can.

  Next, an operation example during printing will be described. The actuator unit 21 has a unimorph type configuration, and the uppermost piezoelectric sheet 41 is an active layer that is displaced by an electric field, and the other three piezoelectric sheets 42 to 44 are inactive layers that are not spontaneously deformed. Yes. The polarization direction of the active layer is the thickness direction. When an electric field is applied in the same direction as the polarization direction (voltage application to the individual electrode 35), the piezoelectric sheet 41 contracts in a direction orthogonal to the polarization direction due to the piezoelectric lateral effect. The piezoelectric sheets 42 to 44 regulate this displacement. As described above, the contraction displacement of the piezoelectric sheet 41 and the displacement regulating effect of the piezoelectric sheets 42 to 44 are combined to be deformed in a convex shape toward the pressure chamber as a whole.

  By this deformation, the volume of the pressure chamber 10 is reduced, the pressure of the ink is increased, and the ink is ejected from the ejection port 8. After that, when the electric field is released from the piezoelectric sheet 41, the piezoelectric sheets 41 to 44 have the original shape and the volume of the pressure chamber 10 returns to the original volume, so that the ink is sucked from the sub manifold channel 55a side.

  As another driving method, the individual electrode 35 is set to a potential different from that of the common electrode 34 in advance, and the individual electrode 35 is once set to the same potential as the common electrode 34 every time there is an ejection request, and then again individually at a predetermined timing. The electrode 35 can be at a different potential from the common electrode 34. In this case, ink is sucked into the pressure chamber 10 from the sub-manifold channel 55a side at the timing when the individual electrode 35 and the common electrode 34 become the same potential. Ink is then ejected at a timing when the individual electrode 35 thereafter has a potential different from that of the common electrode 34.

  Here, a case where a straight line extending in the main scanning direction is printed with a resolution of 600 dpi will be described.

  In the present embodiment, ink discharge starts from the discharge port 8 in the pressure chamber row 11b located at the bottom in FIG. 4, and sequentially communicates with the pressure chambers adjacent to the upper side as the paper is conveyed. The ejection port 8 to be selected is selected and ink is ejected. At this time, every time one pressure chamber line rises from the lower side to the upper side, the ejection port 8 adjacent in the main scanning direction is not selected, so that the ink is sequentially formed along the main scanning direction as the sheet is conveyed. The dots are not formed while being adjacent to each other at equal intervals of 600 dpi.

  In the printing operation in the rectangular area 83, (1), (9), (13), (15), (5), (7), (11), (16), (3) are accompanied with the sheet conveyance. , (8), (12), (14), (4), (6), (10), and (2) are ejected in this order to form an image. At this time, if the number of the discharge port 8 shown in FIG. 4 is N, the main dot position from the first formed dot position is equivalent to (magnification n = N−1) × (interval corresponding to 600 dpi). Ink dots are formed at positions displaced in the scanning direction. When the 16 discharge ports 8 have been finally selected, the interval between the ink dots formed at the interval corresponding to 37.5 dpi by the lowermost discharge port (1) in the drawing is every interval corresponding to 600 dpi. Are connected by 15 dots formed apart from each other. As a result, it is possible to draw a straight line extending in the main scanning direction with a resolution of 600 dpi.

  However, in the overlapping region between the triangular regions 81 and 82, the corresponding ejection port groups are separated in the sub-scanning direction by the respective gaps in one inkjet head 2. Therefore, the printing operation also takes this separation into account. In the regions 85 and 86, the corresponding ejection port groups are also spaced apart in the sub-scanning direction at the respective intervals between the two inkjet heads 2a and 2b. Therefore, as described above, the printing operation also takes this separation into account.

  In one overlapping region R (for example, R2) in the overlapping region in one inkjet head 2, (1), (9), (13), (15), (5) ), (7), (11), (16), (3), (8), (12) and (4) belong to one discharge port group, and (14), (6), (10) and (2) belongs to the other outlet group adjacent to this. Similar to the rectangular region 83, the ejection port 8 is moved to (1), (9), (13), (15), (5), (7), (11), (16), as the paper is conveyed. Ink droplets are ejected in the order of (3), (8), and (12). However, the next (14) discharge port 8 belongs to another discharge port group. Therefore, the discharge from the discharge port 8 of (14) is performed by transporting the sheet by a distance obtained by adding the separation distance of the two discharge port groups to the separation distance of (12) and (14) in the rectangular region 83. After a certain amount of time. Within this time, the paper reaches the (4) discharge port 8 in one of the discharge port groups, and the discharge port 8 discharges ink first. Thereafter, as the sheet is conveyed, the discharge is performed in the order of (14), (6), (10), and (2) belonging to the other discharge port group.

  Further, in the adjacent belt-like region R3, a reverse phenomenon occurs in the printing procedure similar to that of the belt-like region R2, and after discharging from the discharge port 8 of (8), (8) and (12) in the rectangular region 83 The distance obtained by adding the separation distance of the two ejection port groups to the separation distance is waited for the time during which the sheet is conveyed, and then the ejection is performed from the ejection port 8 of (12).

  As described above, in the overlapping region in one inkjet head 2, for each strip region R, the separation of the two ejection port groups is performed when the affiliation of the ejection ports 8 is transferred from one ejection port group to the other ejection port group. There is a waiting time corresponding to. Between the discharge ports 8 that are adjacent in the main scanning direction and belong to different discharge port groups in the transport direction, within the time obtained by adding this waiting time to the discharge timing shift (time difference) in the rectangular region 83 (on the other side) ), The discharge port 8 is discharged first, which is different from the discharge order in the rectangular region 83. In the present embodiment, the belt-shaped region R includes a portion including the rectangular region 83 and the discharge port 8 whose discharge order is before and after, and is alternately formed with a portion having the same discharge order as the rectangular region 83.

  In the connection region between the two inkjet heads 2a and 2b, the discharge port group 71 and the discharge port group 74 do not overlap in the main scanning direction and are separated in the sub-scanning direction. Therefore, ink is ejected in order from the ejection ports 8 of the ejection port group located upstream in the paper conveyance direction. Thereafter, after waiting for a time corresponding to the separation distance between the inkjet heads 2a and 2b, ink is ejected in order from the ejection ports 8 of the ejection port group located downstream.

  As described above, in one inkjet head 2, there is a complementary relationship between the triangular regions 81 and 82 and between the regions 85 and 86 in the connection region of the head set 1 with respect to the arrangement of the ejection ports 8 in the main scanning direction. It has been realized. Thereby, a straight line extending in the main scanning direction and various images can be formed with a resolution of 600 dpi as a whole.

  According to the head unit 5 according to the present embodiment as described above, a head unit (head set) having a long print area formed by combining two inkjet heads 2a and 2b is aligned with the apparatus main body with high accuracy. Even if it is not done, it is possible to suppress the occurrence of streak-like unevenness in the image formed by the ink ejected from the ejection ports 8 belonging to the overlapping regions 85, 86 of the heads 2a, 2b.

  As a modification, the center-to-center distance in the main scanning direction in one region 85 is continuous in the main scanning direction in the other region 86 between the centers of the two ejection ports 8 that are separated by twice the distance corresponding to 600 dpi. The centers of two adjacent discharge ports 8 among the three discharge ports 8 may be arranged. In this case, between the centers of the two discharge ports 8 in the other region 86, the centers of two adjacent discharge ports 8 among the three consecutive discharge ports 8 in the one region 85 are arranged.

  Specifically, the discharge port 8 in the middle of the three consecutive discharge ports 8 in the other region 86 has a distance corresponding to 600 dpi in the main scanning direction from the middle of the two discharge ports 8 in the region 85. It is shifted by 1/2 times. The arrangement of the ejection ports 8 is configured by shifting any one of the inkjet heads 2 by a half of a distance corresponding to 600 dpi in the main scanning direction, as compared with the present embodiment.

  Also in this modified example, as described above, when the head set 1 is assembled to the apparatus main body, it is possible to suppress a decrease in image quality even if the head set 1 is slightly inclined with respect to the main scanning direction. This will be described below with reference to FIG.

  FIG. 14A is an explanatory view showing a projection point when the head set 1 is assembled in parallel to the main scanning direction, and FIG. 14B is an assembly in which the head set 1 is slightly inclined with respect to the main scanning direction. It is explanatory drawing which shows the projection point when it is made. A projection point Q1 shown in FIG. 14 is a projection point from an ejection port 8 in the middle of three consecutive ejection ports 8 in the other region 86, and the projection point Q3 is adjacent to the middle ejection port 8. This is a projection point from the discharge port 8. On the other hand, the projection point Q <b> 2 is a projection point from the two discharge ports 8 in one region 85.

  When the head set 1 is assembled to the apparatus main body, the head set 1 is slightly tilted, and the projection point Q1 just overlaps one of the two projection points Q2 (left side in the figure) from the position shown in FIG. Even if the position is shifted, as shown in FIG. 14B, the projected point Q3 is arranged in the middle between the projected points Q2. For this reason, there is no portion where the distance between the projected points in the main scanning direction is larger than the distance corresponding to 600 dpi between the projected points Q2. As a result, as described above, it is possible to suppress the occurrence of streak-like unevenness in the image formed by the ink ejected from the ejection ports 8 belonging to the regions 85 and 86. Note that, when the head unit 5 is assembled to the apparatus main body, the same effect can be obtained even if the head unit 5 is displaced in the same manner as the head set 1 described above.

  Subsequently, a second embodiment of the present invention will be described. FIG. 15 is an enlarged plan view when the ink jet head according to the second embodiment of the present invention is viewed from below. FIG. 16 is an enlarged view of a region surrounded by an alternate long and short dash line shown in FIG. The inkjet head 202 in the present embodiment has four discharge port groups 271 to 274 similar to the discharge port groups 71 to 74 of the first embodiment. As shown in FIGS. 15 and 16, these discharge port groups 271 to 274 include two discharge port groups in the two inkjet heads 2 a and 2 b of the first embodiment with respect to the main scanning direction. The other arrangements are the same as those of the inkjet head 2 of the first embodiment except that they are arranged so as to have the same positional relationship as 71 and 74. A plurality of holes constituting the individual ink flow path excluding the discharge ports 8 in the flow path unit of the inkjet head 202 are formed at appropriate positions. The same components as those in the first embodiment are denoted by the same reference numerals and the description thereof is omitted.

  The four discharge port groups 271 to 274 are closer to each other in the main scanning direction than in the first embodiment, and are further away from each other in the sub-scanning direction than in the first embodiment. Specifically, as can be understood by comparing FIG. 9 and FIG. 16, the two discharge port groups 272 and 273 in the present embodiment are different from the first embodiment in terms of the sub-scanning direction. The seventh discharge port array 75g and the fifteenth discharge port array 75o are separated by a distance substantially equal to the distance between them.

  Even if the inkjet head 202 is attached with a slight inclination with respect to the main scanning direction by the four ejection port groups 271 to 274 having such a positional relationship, the ejection belonging to the regions 85 and 86 that overlap each other as described above. It is possible to suppress the occurrence of streak-like unevenness in the image formed by the ink ejected from the outlet 8. In addition, the same effect can be acquired in the structure similar to 1st Embodiment. Also in this embodiment, by adopting the same configuration as that of the modification of the first embodiment, the same effect as that of the modification can be obtained.

  The preferred embodiments of the present invention have been described above. However, the present invention is not limited to the above-described embodiments, and various modifications can be made as long as they are described in the claims.

  For example, the head set 1 in the first embodiment described above includes two inkjet heads 2a and 2b, but three or more inkjet heads may be arranged so that the print area extends in the main scanning direction. Moreover, although the head unit 5 has the four head groups 1, it may have one to three and five or more head groups.

  In addition, although the four ejection port groups 71 to 74 and 271 to 274 are formed in the inkjet heads 2 and 202 of the above-described embodiments, 1 to 3 and five or more ejection port groups are formed. Also good. Further, the ejection port group is separated from the region where the ejection ports are arranged at a predetermined distance corresponding to the printing resolution along the main scanning direction, and the ejection port is separated by twice the predetermined distance corresponding to the printing resolution along the main scanning direction. As long as it has a region having a portion, the former planar shape may not be a quadrangle, and the latter planar shape may not have a triangle. Further, the planar shape of the discharge port group may have a shape other than the trapezoidal shape.

  Moreover, although each embodiment mentioned above is an example which applied this invention to the inkjet head (head unit) which discharges an ink from an ejection opening, the applicable object of this invention is not restricted to this. For example, a conductive paste is discharged to form a fine wiring pattern on the substrate, an organic light emitter is discharged to the substrate to form a high-definition display, or an optical resin is discharged to the substrate. The present invention can be applied to a liquid discharge head and a liquid discharge head unit for forming a microelectronic device such as an optical waveguide.

It is a schematic sectional drawing of the inkjet printer which has a head unit by 1st Embodiment of this invention. FIG. 2 is a plan view of the head unit shown in FIG. 1. FIG. 2 is a plan view of the head body shown in FIG. 1. It is an enlarged view of the area | region enclosed with the dashed-dotted line shown in FIG. It is sectional drawing which shows an individual ink flow path. It is a top view of an individual electrode. It is sectional drawing along the VII-VII line of FIG. It is a top view when the head main body of one head group is seen from the lower part. FIG. 9 is an enlarged plan view of a region E surrounded by a two-dot chain line shown in FIG. 8. It is a figure which shows the projection point projected from each discharge port on the straight line extended in the main scanning direction in the overlapping area | region of discharge port groups, and its vicinity. FIG. 9 is an enlarged plan view of a region F surrounded by a two-dot chain line shown in FIG. 8. It is a figure which shows the arrangement | sequence state of the projection point which the discharge outlet in a connection area | region makes. It is explanatory drawing which shows the position of the projection point when a head group inclines a little with respect to the main scanning direction. (A) is explanatory drawing which shows a projection point when a head group is assembled | attached in parallel with the main scanning direction, (b) is a projection point when a head group is assembled | attached a little with respect to the main scanning direction. It is explanatory drawing which shows. It is an enlarged plan view when the inkjet head of 2nd Embodiment of this invention is seen from the downward direction. It is an enlarged view of the area | region enclosed with the dashed-dotted line shown in FIG.

Explanation of symbols

1 Head set 2, 2a, 2b Inkjet head (liquid discharge head)
3a Ink discharge surface 5 Head unit (liquid discharge head unit)
8 Discharge port 71-74, 271-274 Discharge port group 75 Discharge port array 81, 82 Triangle region (second region)
83 square area (first area)
85,86 area | region R1-R8, S, T1-T4, U belt-like area | region

Claims (6)

A plurality of discharge ports each having a long discharge surface in one direction in which a plurality of discharge ports for discharging liquid are formed, and each of the plurality of discharge ports being arranged at predetermined intervals along the one direction on the discharge surface; A plurality of discharge port groups in which the plurality of discharge port arrays are arranged adjacent to each other in a direction orthogonal to the one direction,
The discharge port group includes a first region in which a plurality of discharge ports are arranged at a predetermined distance apart in the one direction, and two discharge ports adjacent to each other in the plurality of discharge ports arranged in the one direction. And an exit having a second region having a portion separated by twice the predetermined distance,
The plurality of discharge port groups are arranged such that the second region of one discharge port group overlaps the second region of another discharge port group along the orthogonal direction,
The plurality of discharge ports constituting the two overlapped second regions of the two discharge ports constituting a portion separated by twice the predetermined distance belonging to the one discharge port group in the one direction. The two discharge ports spaced apart by the predetermined distance in the one direction belonging to the second region of the another discharge port group are arranged between them and separated by twice the predetermined distance belonging to the another discharge port group The two discharge ports spaced apart by the predetermined distance in the one direction belonging to the second region of the one discharge port group are arranged between the two discharge ports constituting the part in the one direction. A liquid discharge head characterized by being arranged. A plurality of discharge ports each having a long discharge surface in one direction in which a plurality of discharge ports for discharging liquid are formed, and each of the plurality of discharge ports being arranged at predetermined intervals along the one direction on the discharge surface; A plurality of discharge port groups in which the plurality of discharge port arrays are arranged adjacent to each other in a direction orthogonal to the one direction,
The discharge port group includes a first region in which a plurality of discharge ports are arranged at a predetermined distance apart in the one direction, and two discharge ports adjacent to each other in the plurality of discharge ports arranged in the one direction. And an exit having a second region having a portion separated by twice the predetermined distance,
The plurality of discharge port groups are arranged such that the second region of one discharge port group overlaps the second region of another discharge port group along the orthogonal direction,
The plurality of discharge ports constituting the two overlapped second regions of the two discharge ports constituting a portion separated by twice the predetermined distance belonging to the one discharge port group in the one direction. Between the three discharge ports that are separated by the predetermined distance in the one direction belonging to the second region of the another discharge port group, the discharge port that is at least in the middle is arranged and belongs to the another discharge port group Of the three outlets separated by the predetermined distance in the one direction belonging to the second region of the one outlet group between the two outlets constituting the part separated by twice the predetermined distance A liquid discharge head, wherein the liquid discharge heads are arranged in the one direction so that at least the discharge ports in the middle are arranged.   The said middle outlet is arrange | positioned in the middle of two said outlets which comprise the part away only 2 times of the said predetermined distance regarding the said one direction. Liquid discharge head. A plurality of discharge ports each having a long discharge surface in one direction in which a plurality of discharge ports for discharging liquid are formed, and each of the plurality of discharge ports being arranged at predetermined intervals along the one direction on the discharge surface; A plurality of liquid discharge heads, each of which includes a plurality of discharge port arrays and a plurality of discharge port groups arranged adjacent to each other in a direction orthogonal to the one direction,
The discharge port group includes a first region in which a plurality of discharge ports are arranged at a predetermined distance in the one direction, and two discharge ports adjacent to each other in the one direction. And an exit having a second region having a portion separated by twice the predetermined distance,
The plurality of liquid ejection heads are arranged in parallel to each other such that the second area of one liquid ejection head overlaps the second area of another liquid ejection head along the orthogonal direction. And
Between the two ejection ports constituting the portion where the plurality of ejection ports constituting the two overlapped second regions are separated by twice the predetermined distance of the one liquid ejection head in the one direction. The two discharge ports that are separated by the predetermined distance in the one direction belonging to the second region of the another liquid discharge head are disposed at a portion separated by twice the predetermined distance of the other liquid discharge head. The two ejection ports that are separated by the predetermined distance in the one direction belonging to the second region of the one liquid ejection head are arranged in the one direction so as to be disposed between the two ejection ports constituting the same. A liquid discharge head unit. A plurality of discharge ports each having a long discharge surface in one direction in which a plurality of discharge ports for discharging liquid are formed, and each of the plurality of discharge ports being arranged at predetermined intervals along the one direction on the discharge surface; A plurality of liquid discharge heads, each of which includes a plurality of discharge port arrays and a plurality of discharge port groups arranged adjacent to each other in a direction orthogonal to the one direction,
The discharge port group includes a first region in which a plurality of discharge ports are arranged at a predetermined distance apart in the one direction, and two discharge ports adjacent to each other in the plurality of discharge ports arranged in the one direction. And an exit having a second region having a portion separated by twice the predetermined distance,
The plurality of liquid ejection heads are arranged in parallel to each other such that the second area of one liquid ejection head overlaps the second area of another liquid ejection head along the orthogonal direction. And
Between the two ejection ports constituting the portion where the plurality of ejection ports constituting the two overlapped second regions are separated by twice the predetermined distance of the one liquid ejection head in the one direction. At least one of the three discharge ports that are separated by the predetermined distance in the one direction belonging to the second region of the another liquid discharge head is disposed, and the predetermined port of the other liquid discharge head is disposed. At least the middle of the three discharge ports separated by the predetermined distance in the one direction belonging to the second region of the one liquid discharge head between the two discharge ports constituting the part separated by twice the distance The liquid discharge head unit is arranged in the one direction so that the discharge ports are disposed in the same direction.   The said middle outlet is arrange | positioned in the middle of two said outlets which comprise the part away only 2 times of the said predetermined distance regarding the said one direction. Liquid discharge head unit.

Images