EP1336488A2 - Tête d'impression jet d'encre et imprimante l'utilisant - Google Patents

Tête d'impression jet d'encre et imprimante l'utilisant Download PDF

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Publication number
EP1336488A2
EP1336488A2 EP03003697A EP03003697A EP1336488A2 EP 1336488 A2 EP1336488 A2 EP 1336488A2 EP 03003697 A EP03003697 A EP 03003697A EP 03003697 A EP03003697 A EP 03003697A EP 1336488 A2 EP1336488 A2 EP 1336488A2
Authority
EP
European Patent Office
Prior art keywords
pressure chamber
ink
common ink
nozzle
pressure
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
EP03003697A
Other languages
German (de)
English (en)
Other versions
EP1336488A3 (fr
EP1336488B1 (fr
Inventor
Atsuo Sakaida
Hidetoshi Watanabe
Atsushi Hirota
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Brother Industries Ltd
Original Assignee
Brother Industries Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Brother Industries Ltd filed Critical Brother Industries Ltd
Priority to EP09167614.8A priority Critical patent/EP2213456B1/fr
Publication of EP1336488A2 publication Critical patent/EP1336488A2/fr
Publication of EP1336488A3 publication Critical patent/EP1336488A3/fr
Application granted granted Critical
Publication of EP1336488B1 publication Critical patent/EP1336488B1/fr
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41J—TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
    • B41J2/00—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed
    • B41J2/005—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by bringing liquid or particles selectively into contact with a printing material
    • B41J2/01—Ink jet
    • B41J2/135—Nozzles
    • B41J2/14—Structure thereof only for on-demand ink jet heads
    • B41J2/14201—Structure of print heads with piezoelectric elements
    • B41J2/14209—Structure of print heads with piezoelectric elements of finger type, chamber walls consisting integrally of piezoelectric material
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41J—TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
    • B41J2/00—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed
    • B41J2/005—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by bringing liquid or particles selectively into contact with a printing material
    • B41J2/01—Ink jet
    • B41J2/135—Nozzles
    • B41J2/145—Arrangement thereof
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41J—TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
    • B41J2/00—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed
    • B41J2/005—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by bringing liquid or particles selectively into contact with a printing material
    • B41J2/01—Ink jet
    • B41J2/135—Nozzles
    • B41J2/14—Structure thereof only for on-demand ink jet heads
    • B41J2/14201—Structure of print heads with piezoelectric elements
    • B41J2/14209—Structure of print heads with piezoelectric elements of finger type, chamber walls consisting integrally of piezoelectric material
    • B41J2002/14217—Multi layer finger type piezoelectric element
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41J—TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
    • B41J2/00—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed
    • B41J2/005—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by bringing liquid or particles selectively into contact with a printing material
    • B41J2/01—Ink jet
    • B41J2/135—Nozzles
    • B41J2/14—Structure thereof only for on-demand ink jet heads
    • B41J2/14201—Structure of print heads with piezoelectric elements
    • B41J2/14209—Structure of print heads with piezoelectric elements of finger type, chamber walls consisting integrally of piezoelectric material
    • B41J2002/14225—Finger type piezoelectric element on only one side of the chamber
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41J—TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
    • B41J2/00—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed
    • B41J2/005—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by bringing liquid or particles selectively into contact with a printing material
    • B41J2/01—Ink jet
    • B41J2/135—Nozzles
    • B41J2/14—Structure thereof only for on-demand ink jet heads
    • B41J2/14201—Structure of print heads with piezoelectric elements
    • B41J2002/14306—Flow passage between manifold and chamber
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41J—TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
    • B41J2/00—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed
    • B41J2/005—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by bringing liquid or particles selectively into contact with a printing material
    • B41J2/01—Ink jet
    • B41J2/135—Nozzles
    • B41J2/14—Structure thereof only for on-demand ink jet heads
    • B41J2002/14459—Matrix arrangement of the pressure chambers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41J—TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
    • B41J2/00—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed
    • B41J2/005—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by bringing liquid or particles selectively into contact with a printing material
    • B41J2/01—Ink jet
    • B41J2/135—Nozzles
    • B41J2/14—Structure thereof only for on-demand ink jet heads
    • B41J2002/14491—Electrical connection
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41J—TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
    • B41J2202/00—Embodiments of or processes related to ink-jet or thermal heads
    • B41J2202/01—Embodiments of or processes related to ink-jet heads
    • B41J2202/20—Modules

Definitions

  • the present invention relates to an ink-jet head for printing by ejecting ink onto a record medium, and to an ink-jet printer having the ink-jet head.
  • an ink-jet head distributes ink, which is supplied from an ink tank, to pulse pressure chambers.
  • the ink-jet head selectively applies pressure to each pressure chamber to eject ink through a nozzle connected with each pressure chamber.
  • an actuator unit or the like may be used in which ceramic piezoelectric sheets are laminated. The printing operations are carried out while reciprocating such a head at high speed in widthwise direction of the paper.
  • ink-jet head As for arrangement of pressure chambers in such an ink-jet head, there are one-dimensional arrangement in which pressure chambers are arranged in, e.g., one or two rows along the length of the head, and two-dimensional arrangement in which pressure chambers are arranged in a matrix along a surface of the head. To achieve high-resolution and high-speed printing demanded in recent years, two-dimensional arrangement of pressure chambers is more effective.
  • ink-jet head in which pressure chambers are arranged in a matrix along a surface of the head
  • an ink-jet head is known in which a nozzle is disposed at the center of each pressure chamber in a view perpendicular to the head surface (see US Patent 5,757,400).
  • the width of a common ink passage for supplying ink may be restricted by each interval of nozzles corresponding to neighboring pressure chambers. This is because the common ink passage must be disposed so as not to overlap the nozzle at the center of each pressure chamber in a view perpendicular to the head surface. Besides, in this case, if nozzles are arranged at a high density to meet the demands of high-resolution and high-speed printing, it may restrict the width of the common ink passage. If the width of the common ink passage is thus restricted, the passage resistance of the common ink passage to ink is high and so smoothness of ink supply corresponding to the maximum ink ejection cycle can not be achieved.
  • An object of the present invention is to provide an ink-jet head in which smoothness of ink supply can be achieved, and to provide an ink-jet printer having the ink-jet head.
  • an ink-jet head including a passage unit comprising a plurality of pressure chambers each connected with a nozzle and arranged in a matrix in a plane to form a plurality of pressure chamber rows in a first direction in the plane, and a plurality of common ink passages each extending along the first direction and communicating with the pressure chambers.
  • the pressure chamber rows include first pressure chamber rows each constituted by pressure chambers each connected with a nozzle deviated on one side thereof with respect to a second direction crossing the first direction, and second pressure chamber rows each constituted by pressure chambers each connected with a nozzle deviated on the other side thereof with respect to the second direction, when viewing from a third direction perpendicular to the plane.
  • Each of the common ink passages includes at least a boundary region between one of the first pressure chamber rows and one of the second pressure chamber rows neighboring each other so that nozzles connected with the pressure chambers in the each pressure chamber rows face outward each other when viewing from the third direction.
  • Each of the common ink passages does not overlap any of the nozzles.
  • an ink-jet printer including an ink-jet head.
  • the ink-jet head comprises a passage unit including a plurality of pressure chambers each connected with a nozzle and arranged in a matrix in a plane to form a plurality of pressure chamber rows in a first direction in the plane, and a plurality of common ink passages each extending along the first direction and communicating with the pressure chambers.
  • the pressure chamber rows include first pressure chamber rows each constituted by pressure chambers each connected with a nozzle deviated on one side thereof with respect to a second direction crossing the first direction, and second pressure chamber rows each constituted by pressure chambers each connected with a nozzle deviated on the other side thereof with respect to the second direction, when viewing from a third direction perpendicular to the plane.
  • Each of the common ink passages includes at least a boundary region between one of the first pressure chamber rows and one of the second pressure chamber rows neighboring each other so that nozzles connected with the pressure chambers in the each pressure chamber rows face outward each other when viewing from the third direction.
  • Each of the common ink passages does not overlap any of the nozzles.
  • each nozzle is not disposed at the center of the corresponding pressure chamber but deviated to one side of the pressure chamber when viewing from the third direction perpendicular to the surface, and each common ink passage is disposed so as to include the boundary region between the first and second pressure chamber rows in which nozzles are deviated to opposite sides to each other with respect to the first direction, the width of each common ink passage can be made large. Therefore, even when the thickness (depth) of each common ink passage in the above third direction is fixed, the passage resistance of the common ink passage to ink is low and smooth ink supply to each pressure chamber can be performed.
  • FIG. 1 is a general view of an ink-jet printer including ink-jet heads according to an embodiment of the present invention.
  • the ink-jet printer 101 as illustrated in FIG. 1 is a color ink-jet printer having four ink-jet heads 1.
  • a paper feed unit 111 and a paper discharge unit 112 are disposed in left and right portions of FIG. 1, respectively.
  • a paper transfer path is provided extending from the paper feed unit 111 to the paper discharge unit 112.
  • a pair of feed rollers 105a and 105b is disposed immediately downstream of the paper feed unit 111 for pinching and putting forward a paper as an image record medium.
  • the paper is transferred from the left to the right in FIG. 1.
  • two belt rollers 106 and 107 and an endless transfer belt 108 are disposed.
  • the transfer belt 108 is wound on the belt rollers 106 and 107 to extend between them.
  • the outer face, i.e., the transfer face, of the transfer belt 108 has been treated with silicone.
  • a paper fed through the pair of feed rollers 105a and 105b can be held on the transfer face of the transfer belt 108 by the adhesion of the face.
  • the paper is transferred downstream (rightward) by driving one belt roller 106 to rotate clockwise in FIG. 1 (the direction indicated by an arrow 104).
  • Pressing members 109a and 109b are disposed at positions for feeding a paper onto the belt roller 106 and taking out the paper from the belt roller 106, respectively. Either of the pressing members 109a and 109b is for pressing the paper onto the transfer face of the transfer belt 108 so as to prevent the paper from separating from the transfer face of the transfer belt 108. Thus, the paper surely adheres to the transfer face.
  • a peeling device 110 is provided immediately downstream of the transfer belt 108 along the paper transfer path.
  • the peeling device 110 peels off the paper, which has adhered to the transfer face of the transfer belt 108, from the transfer face to transfer the paper toward the rightward paper discharge unit 112.
  • Each of the four ink-jet heads 1 has, at its lower end, a head main body 1a.
  • Each head main body 1a has a rectangular section.
  • the head main bodies 1a are arranged close to each other with the longitudinal axis of each head main body 1a being perpendicular to the paper transfer direction (perpendicular to FIG. 1). That is, this printer 101 is a line type.
  • the bottom of each of the four head main bodies 1a faces the paper transfer path.
  • a number of nozzles are provided each having a small-diameter ink ejection port.
  • the four head main bodies 1a eject ink of magenta, yellow, cyan, and black, respectively.
  • the head main bodies 1a are disposed such that a narrow clearance is formed between the lower face of each head main body 1a and the transfer face of the transfer belt 108.
  • the paper transfer path is formed within the clearance.
  • the ink-jet printer 101 is provided with a maintenance unit 117 for automatically carrying out maintenance of the ink-jet heads 1.
  • the maintenance unit 117 includes four caps 116 for covering the lower faces of the four head main bodies 1a, and a not-illustrated purge system.
  • the maintenance unit 117 is at a position immediately below the paper feed unit 111 (withdrawal position) while the ink-jet printer 101 operates to print.
  • a predetermined condition for example, when a state in which no printing operation is performed continues for a predetermined time period or when the printer 101 is powered off
  • the maintenance unit 117 moves to a position immediately below the four head main bodies 1a (cap position), where the maintenance unit 117 covers the lower faces of the head main bodies 1a with the respective caps 116 to prevent ink in the nozzles of the head main bodies 1a from being dried.
  • the belt rollers 106 and 107 and the transfer belt 108 are supported by a chassis 113.
  • the chassis 113 is put on a cylindrical member 115 disposed under the chassis 113.
  • the cylindrical member 115 is rotatable around a shaft 114 provided at a position deviating from the center of the cylindrical member 115.
  • the shaft 114 By rotating the shaft 114, the level of the uppermost portion of the cylindrical member 115 can be changed to move up or down the chassis 113 accordingly.
  • the cylindrical member 115 When the maintenance unit 117 is moved from the withdrawal position to the cap position, the cylindrical member 115 must have been rotated at a predetermined angle in advance so as to move down the transfer belt 108 and the belt rollers 106 and 107 by a pertinent distance from the position illustrated in FIG. 1. A space for the movement of the maintenance unit 117 is thereby ensured.
  • a nearly rectangular parallelepiped guide 121 (having its width substantially equal to that of the transfer belt 108) is disposed at an opposite position to the ink-jet heads 1.
  • the guide 121 is in contact with the lower face of the upper part of the transfer belt 108 to support the upper part of the transfer belt 108 from the inside.
  • FIG. 2 is a perspective view of the ink-jet head 1.
  • FIG. 3 is a sectional view taken along line II-II in FIG. 2.
  • the ink-jet head 1 according to this embodiment includes a head main body 1a having a rectangular shape in a plan view and extending in one direction (main scanning direction), and a base portion 131 for supporting the head main body 1a.
  • the base portion 131 supporting the head main body 1a further supports thereon driver ICs 132 for supplying driving signals to individual electrodes 35a and 35b (see FIG. 6 and FIG. 10), and substrates 133.
  • the base portion 131 is made up of a base block 138 partially bonded to the upper face of the head main body 1a to support the head main body 1a, and a holder 139 bonded to the upper face of the base block 138 to support the base block 138.
  • the base block 138 is a nearly rectangular parallelepiped member having substantially the same length of the head main body 1a.
  • the base block 138 made of metal material such as stainless steel has a function as a light structure for reinforcing the holder 139.
  • the holder 139 is made up of a holder main body 141 disposed near the head main body 1a, and a pair of holder support portions 142 each extending on the opposite side of the holder main body 141 to the head main body 1a.
  • Each holder support portion 142 is a flat member. These holder support portions 142 extend along the longitudinal direction of the holder main body 141 and are disposed in parallel with each other at a predetermined interval.
  • Skirt portions 141a in a pair, protruding downward, are provided in both end portions of the holder main body 141a in a sub scanning direction (perpendicular to the main scanning direction). Either skirt portion 141a is formed through the length of the holder main body 141. As a result, in the lower portion of the holder main body 141, a nearly rectangular parallelepiped groove 141b is defined by the pair of skirt portions 141a.
  • the base block 138 is received in the groove 141b.
  • the upper surface of the base block 138 is bonded to the bottom of the groove 141b of the holder main body 141 with an adhesive.
  • the thickness of the base block 138 is somewhat larger than the depth of the groove 141b of the holder main body 141. As a result, the lower end of the base block 138 protrudes downward beyond the skirt portions 141a.
  • an ink reservoir 3 is formed as a nearly rectangular parallelepiped space (hollow region) extending along the longitudinal direction of the base block 138.
  • openings 3b are formed each communicating with the ink reservoir 3.
  • the ink reservoir 3 is connected through a not-illustrated supply tube with a not-illustrated main ink tank (ink supply source) within the printer main body.
  • the ink reservoir 3 is suitably supplied with ink from the main ink tank.
  • each opening 3b protrudes downward from the surrounding portion.
  • the base block 138 is in contact with a passage unit 4 (see FIG. 3) of the head main body 1a at the only vicinity portion 145a of each opening 3b of the lower face 145.
  • the region of the lower face 145 of the base block 138 other than the vicinity portion 145a of each opening 3b is distant from the head main body 1a.
  • Actuator units 21 are disposed within the distance.
  • a driver IC 132 is fixed with an elastic member 137 such as a sponge being interposed between them.
  • a heat sink 134 is disposed in close contact with the outer side face of the driver IC 132.
  • the heat sink 134 is made of a nearly rectangular parallelepiped member for efficiently radiating heat generated in the driver IC 132.
  • a flexible printed circuit (FPC) 136 as a power supply member is connected with the driver IC 132.
  • the FPC 136 connected with the driver IC 132 is bonded to and electrically connected with the corresponding substrate 133 and the head main body 1a by soldering.
  • the substrate 133 is disposed outside the FPC 136 above the driver IC 132 and the heat sink 134.
  • the upper face of the heat sink 134 is bonded to the substrate 133 with a seal member 149.
  • the lower face of the heat sink 134 is bonded to the FPC 136 with a seal member 149.
  • a seal member 150 is disposed to sandwich the FPC 136.
  • the FPC 136 is fixed by the seal member 150 to the passage unit 4 and the holder main body 141. Therefore, even if the head main body 1a is elongated, the head main body 1a can be prevented from being bent, the interconnecting portion between each actuator unit and the FPC 136 can be prevented from receiving stress, and the FPC 136 can surely be held.
  • protruding portions 30a are disposed at regular intervals along the corresponding side wall of the ink-jet head 1. These protruding portions 30a are provided at both ends in the sub scanning direction of a nozzle plate 30 in the lowermost layer of the head main body 1a (see FIG. 7).
  • the nozzle plate 30 is bent by about 90 degrees along the boundary line between each protruding portion 30a and the other portion.
  • the protruding portions 30a are provided at positions corresponding to the vicinities of both ends of various papers to be used for printing.
  • Each bent portion of the nozzle plate 30 has a shape not right-angled but rounded. This makes it hard to bring about clogging of a paper, i.e., jamming, which may occur because the leading edge of the paper, which has been transferred to approach the head 1, is stopped by the side face of the head 1.
  • FIG. 4 is a schematic plan view of the head main body 1a.
  • an ink reservoir 3 formed in the base block 138 is imaginarily illustrated with a broken line.
  • the head main body 1a has a rectangular shape in the plan view extending in one direction (main scanning direction).
  • the head main body 1a includes a passage unit 4 in which a large number of pressure chambers 10 and a large number of ink ejection ports 8 at the front ends of nozzles (as for both, see FIGS. 5, 6, and 7), as described later.
  • Trapezoidal actuator units 21 arranged in two lines in a staggered shape are bonded onto the upper face of the passage unit 4.
  • Each actuator unit 21 is disposed such that its parallel opposed sides (upper and lower sides) extend along the longitudinal direction of the passage unit 4.
  • the oblique sides of each neighboring actuator units 21 overlap each other in the lateral direction of the passage unit 4.
  • the lower face of the passage unit 4 corresponding to the bonded region of each actuator unit 4 is made into an ink ejection region.
  • a large number of ink ejection ports 8 are arranged in a matrix, as described later.
  • an ink reservoir 3 is formed along the longitudinal direction of the base block 138.
  • the ink reservoir 3 communicates with an ink tank (not illustrated) through an opening 3a provided at one end of the ink reservoir 3, so that the ink reservoir 3 is always filled up with ink.
  • pairs of openings 3b are provided in regions where no actuator unit 21 is present, so as to be arranged in a staggered shape along the longitudinal direction of the ink reservoir 3.
  • FIG. 5 is an enlarged view of the region enclosed with an alternate long and short dash line in FIG. 4.
  • the ink reservoir 3 communicates through each opening 3b with a manifold channel 5 disposed under the opening 3b.
  • Each opening 3b is provided with a filter (not illustrated) for catching dust and dirt contained in ink.
  • the front end portion of each manifold channel 5 branches into two sub-manifold channels 5a.
  • two sub-manifold channels 5a extend from each of the two openings 3b on both sides of the actuator unit 21 in the longitudinal direction of the ink-jet head 1. That is, below the single actuator unit 21, four sub-manifold channels 5a in total extend along the longitudinal direction of the ink-jet head 1.
  • Each sub-manifold channel 5a functions as a common ink passage and it is filled up with ink supplied from the ink reservoir 3.
  • FIG. 6 is an enlarged view of the region enclosed with an alternate long and short dash line in FIG. 5.
  • Either of FIGS. 5 and 6 is a vertical view of a plane in which many pressure chambers 10 are arranged in a matrix in the passage unit 4. Pressure chambers 10, apertures 12, nozzles 8, sub-manifold channels, etc., as components of the passage unit 4, are disposed at different levels from one another perpendicularly to FIGS. 5 and 6 (see FIG. 7).
  • the pressure chambers 10 are connected with nozzles (FIGS. 5 and 6 illustrates ink ejection ports 8 formed at the tip ends of the respective nozzles), respectively.
  • the pressure chambers 10 are arranged along the surface of each trapezoidal ink ejection region illustrated in FIG. 5, in a matrix in two directions, i.e., an arrangement direction A (arrangement direction A) and an arrangement direction B (along a vertical oblique side of a parallelogrammic region 10x illustrated in FIG. 6).
  • Each pressure chamber 10 has a nearly parallelogrammic shape (length: 900 ⁇ m, width: 350 ⁇ m) in a plan view whose corners are rounded.
  • Each pressure chamber 10 is included within the corresponding one of parallelogrammic regions 10x arranged in a matrix.
  • the parallelogrammic regions 10x are arranged in a matrix with neighboring each other without overlapping each other so that each parallelogrammic region 10x may have its sides in common with those of other parallelogrammic regions 10x.
  • the pressure chamber 10 in each parallelogrammic region 10x is so disposed as to have its center coinciding with the center of the parallelogrammic region 10x. As a result, the pressure chambers 10 are separated from one another. As illustrated in FIG. 7, one end of each pressure chamber 10 is connected with a nozzle and the other end is connected with a sub-manifold channel 5a as a common ink passage.
  • FIG. 6 illustrates pairs of individual electrodes 35a and 35b each overlapping the corresponding pressure chamber 10 in a plan view and having a shape in a plan view similar to that of the pressure chamber 10 and somewhat smaller than the pressure chamber 10.
  • the pressure chambers 10 arranged in a matrix constitute pressure chamber rows along the arrangement direction A (first direction) in FIG. 6.
  • the pressure chamber rows are classified into first and second pressure chamber rows 11a and 11b in accordance with the disposition of the nozzle connected with each pressure chamber 10.
  • the pressure chambers 10 constituting each first pressure chamber row 11a when viewing perpendicularly to FIG. 6 (third direction), the nozzles connected with the pressure chambers 10 and the ink ejection ports 8 formed at the tip ends of the respective nozzles are deviated upward in FIG. 6, with respect to the longer diagonal of each parallelogrammic region 10x (second direction) crossing the arrangement direction A. That is, as illustrated in FIG.
  • each pressure chamber 10 constituting each first pressure chamber row 11a in this embodiment in each pressure chamber 10 constituting each first pressure chamber row 11a in this embodiment, the ink ejection port 8 is disposed at the upper end of the corresponding parallelogrammic region 10x.
  • the nozzles connected with the pressure chambers 10 and the ink ejection ports 8 formed at the tip ends of the respective nozzles are deviated downward in FIG. 6, with respect to the second direction. That is, as illustrated in FIG. 6, in each pressure chamber 10 constituting each second pressure chamber row 11b in this embodiment, the ink ejection port 8 is disposed at the lower end of the corresponding parallelogrammic region 10x.
  • Two first pressure chamber rows 11a and two second pressure chamber rows 11b are alternately arranged.
  • the arrangement direction A (first direction) in FIG. 6 is along the length of the ink-jet head 1 and the arrangement direction B is along an oblique side of each parallelogrammic region 10x somewhat oblique to the width of the ink-jet head 1.
  • Each sub-manifold channel 5a which functions as a common ink passage, extends in the arrangement direction A and communicates with pressure chambers 10 disposed on both sides of the sub-manifold channel 5a.
  • each sub-manifold channel 5a extends to include first and second pressure chamber rows 11a and 11b neighboring each other so that the nozzles and the ink ejection ports 8 at the tip ends of the respective nozzles may face outward of the sub-manifold channel 5a.
  • the sub-manifold channel 5a extends not to overlap the nozzles and the ink ejection ports 8 at the tip ends of the respective nozzles.
  • each sub-manifold channel 5a preferably includes the most parts of the neighboring first and second pressure chamber rows 11a and 11b as long as the sub-manifold channel 5a does not overlap the nozzles and the ink ejection ports 8. That is, to smoothly supply ink to each pressure chamber 10 communicating with the sub-manifold channel 5a, the limit of the width of the sub-manifold channel 5a is preferably set near the one end of each pressure chamber 10 connected with the ink ejection port 8. By this, even when the thickness of each sub-manifold channel 5a in the above third direction (depth) is fixed, the passage resistance of the sub-manifold channel 5a to ink can be reduced.
  • FIG. 7 is a partial sectional view of the head main body 1a of FIG. 4.
  • each ink ejection port 8 is formed at the tip end of a tapered nozzle.
  • an aperture 12 extends substantially in parallel with the surface of the passage unit 4, like the pressure chamber 10. This aperture 12 is for restricting the ink flow to give the passage a suitable resistance, thereby achieving the stabilization of ink ejection.
  • Each ink ejection port 8 communicates with a sub-manifold channel 5a through a pressure chamber 10 (length: 900 ⁇ m, width: 350 ⁇ m) and an aperture 12.
  • ink passages 32 each extending from an ink tank to an ink ejection port 8 through an ink reservoir 3, a manifold channel 5, a sub-manifold channel 5a, an aperture 12, and a pressure chamber 10.
  • a nozzle connected with a pressure chamber 10 constituting a second pressure chamber row 11b is disposed on the right side of the sub-manifold channel 5a in FIG. 7.
  • each of the pressure chamber 10, the aperture 12, and the sub-manifold channel 5a is formed within layered sheet members. When viewing from the above third direction, they are disposed so as to overlap one another.
  • the pressure wave to contribute ink ejection propagates in the pressure chamber 10 along the longer diagonal of the corresponding parallelogrammic region 10x (second direction).
  • the pressure chamber 10 is generally made into a shape in a plan view symmetrical with respect to the origin, such as a circle or a regular polygon.
  • the pressure chamber 10 when the pressure wave propagating in the pressure chamber 10 in a specific direction along the surface of the passage unit 4 is utilized for ink ejection, the pressure chamber 10 is preferably made into a shape in a plan view slender in the pressure wave propagation direction because the ink ejection amount and ejection period are made easy to control by increasing the propagation time length of the pressure wave (Al: Acoustic Length).
  • pressure chambers 10 are arranged within an ink ejection region in two directions, i.e., a direction along the length of the ink-jet head 1 (arrangement direction A) and a direction somewhat inclining from the width of the ink-jet head 1 (arrangement direction B).
  • the arrangement directions A and B form an angle 'theta' somewhat smaller than the right angle.
  • the ink ejection ports 8 are arranged at 50 dpi (dots per inch) in the arrangement direction A.
  • the pressure chambers 10 are arranged in the arrangement direction B such that the ink ejection region corresponding to one actuator unit 21 may include twelve pressure chambers 10.
  • ink-jet head 1 by ejecting ink droplets in order through a large number of ink ejection ports 8 arranged in the arrangement directions A and B with relative movement of a paper along the width of the ink-jet head 1, printing at 600 dpi in the main scanning direction can be performed.
  • pressure chambers 10 are arranged in lines in the arrangement direction A at predetermined intervals at 500 dpi. Twelve lines of pressure chambers 10 are arranged in the arrangement direction B. As the whole, the pressure chambers 10 are two-dimensionally arranged in the ink ejection region corresponding to one actuator unit 21.
  • the pressure chambers 10 are classified into two kinds, i.e., pressure chambers 10a in each of which a nozzle is connected with the upper acute portion in FIG. 8, and pressure chambers 10b in each of which a nozzle is connected with the lower acute portion.
  • Pressure chambers 10a and 10b are arranged in the arrangement direction A to form pressure chamber rows 11a and 11b, respectively.
  • FIG. 8 in the ink ejection region corresponding to one actuator unit 21, from the lower side of FIG. 8, there are disposed two pressure chamber rows 11a and two pressure chamber rows 11b neighboring the upper side of the pressure chamber rows 11a.
  • the four pressure chamber rows of the two pressure chamber rows 11a and the two pressure chamber rows 11b constitute a set of pressure chamber rows.
  • Such a set of pressure chamber rows is repeatedly disposed three times from the lower side in the ink ejection region corresponding to one actuator unit 21.
  • each four pressure chamber rows constitute a set of pressure chamber rows and such a set of pressure chamber rows is repeatedly disposed three times from the lower side as described above, there is formed a region where no nozzle exists, in the vicinity of the boundary between each neighboring sets of pressure chamber rows, i.e., on both sides of each set of pressure chamber rows constituted by four pressure chamber rows.
  • Wide sub-manifold channels 5a extend there for supplying ink to the corresponding pressure chambers 10.
  • four wide sub-manifold channels 5a in total are arranged in the arrangement direction A, i.e., one on the lower side of FIG. 8, one between the lowermost set of pressure chamber rows and the second lowermost set of pressure chamber rows, and two on both sides of the uppermost set of pressure chamber rows.
  • nozzles communicating with ink ejection ports 8 for ejecting ink are arranged in the arrangement direction A at regular intervals at 50 dpi to correspond to the respective pressure chambers 10 regularly arranged in the arrangement direction A.
  • twelve pressure chambers 10 are regularly arranged also in the arrangement direction B forming an angle 'theta' with the arrangement direction A
  • twelve nozzles corresponding to the twelve pressure chambers 10 include ones each communicating with the upper acute portion of the corresponding pressure chamber 10 and ones each communicating with the lower acute portion of the corresponding pressure chamber 10, as a result, they are not regularly arranged in the arrangement direction B at regular intervals.
  • the nozzles are regularly arranged also in the arrangement direction B at regular intervals.
  • nozzles are arranged so as to shift in the arrangement direction A by a distance corresponding to 600 dpi as resolution upon printing per pressure chamber row from the lower side to the upper side of FIG. 8.
  • the shift of nozzle position in the arrangement direction A per pressure chamber row from the lower side to the upper side of FIG. 8 is not always the same.
  • a band region R will be discussed that has a width (about 508.0 ⁇ m) corresponding to 50 dpi in the arrangement direction A and extends perpendicularly to the arrangement direction A.
  • any of twelve pressure chamber rows includes only one nozzle. That is, when such a band region R is defined at an optional position in the ink ejection region corresponding to one actuator unit 21, twelve nozzles are always distributed in the band region R.
  • the positions of points respectively obtained by projecting the twelve nozzles onto a straight line extending in the arrangement direction A are distant from each other by a distance corresponding to 600 dpi as resolution upon printing.
  • the twelve nozzles included in one band region R are denoted by (1) to (12) in order from one whose projected image onto a straight line extending in the arrangement direction A is the leftmost, the twelve nozzles are arranged in the order of (1), (7), (2), (8), (5), (11), (6), (12), (9), (3), (10), and (4) from the lower side.
  • a character, an figure, or the like having a resolution of 600 dpi can be formed. That is, by selectively driving active layers corresponding to the twelve pressure chamber rows in order in accordance with the transfer of a print medium, a specific character or figure can be printed on the print medium.
  • a case will be described wherein a straight line extending in the arrangement direction A is printed at a resolution of 600 dpi.
  • nozzles communicate with the same-side acute portions of pressure chambers 10.
  • ink ejection starts from a nozzle in the lowermost pressure chamber row in FIG. 8.
  • Ink ejection is then shifted upward with selecting a nozzle belonging to the upper neighboring pressure chamber row in order.
  • Ink dots are thereby formed in order in the arrangement direction A with neighboring each other at 600 dpi.
  • all the ink dots form a straight line extending in the arrangement direction A at a resolution of 600 dpi.
  • ink ejection starts from a nozzle in the lowermost pressure chamber row 11a in FIG. 8, and ink ejection is then shifted upward with selecting a nozzle communicating with the upper neighboring pressure chamber row in order in accordance with transfer of a print medium.
  • ink dots formed in order in the arrangement direction A in accordance with the transfer of the print medium are not arranged at regular intervals at 600 dpi.
  • ink is first ejected through a nozzle (1) communicating with the lowermost pressure chamber row 11a in FIG. 8 to form a dot row on the print medium at intervals corresponding to 50 dpi (about 508.0 ⁇ m).
  • a nozzle (7) communicating with the second lowermost pressure chamber row 11a ink is ejected through the nozzle (7).
  • ink is ejected through the nozzle (5).
  • ink dots are formed with selecting nozzles communicating with pressure chambers 10 in order from the lower side to the upper side in FIG. 8.
  • N the number of a nozzle in FIG. 8
  • FIG. 9 is a partial exploded view of the head main body 1a of FIG. 4.
  • a principal portion on the bottom side of the ink-jet head 1 has a layered structure laminated with ten sheet materials in total, i.e., from the top, an actuator unit 21, a cavity plate 22, a base plate 23, an aperture plate 24, a supply plate 25, manifold plates 26, 27, and 28, a cover plate 29, and a nozzle plate 30.
  • nine plates other than the actuator unit 21 constitute the passage unit 4.
  • the actuator unit 21 is laminated with five piezoelectric sheets and provided with electrodes so that three of them may include layers to be active when an electric field is applied (hereinafter, simply referred to as "layer including active layers") and the remaining two layers may be inactive.
  • the cavity plate 22 is made of metal, in which a large number of substantially rhombic openings are formed corresponding to the respective pressure chambers 10.
  • the base plate 23 is made of metal, in which a communication hole between each pressure chamber 10 of the cavity plate 22 and the corresponding aperture 12, and a communication hole between the pressure chamber 10 and the corresponding ink ejection port 8 are formed.
  • the aperture plate 24 is made of metal, in which, in addition to apertures 12, communication holes are formed for connecting each pressure chamber 10 of the cavity plate 22 with the corresponding ink ejection port 8.
  • the supply plate 25 is made of metal, in which communication holes between each aperture 12 and the corresponding sub-manifold channel 5a and communication holes for connecting each pressure chamber 10 of the cavity plate 22 with the corresponding ink ejection port 8 are formed.
  • Each of the manifold plates 26, 27, and 28 is made of metal, which defines an upper portion of each sub-manifold channel 5a and in which communication holes are formed for connecting each pressure chamber 10 of the cavity plate 22 with the corresponding ink ejection port 8.
  • the cover plate 29 is made of metal, in which communication holes are formed for connecting each pressure chamber 10 of the cavity plate 22 with the corresponding ink ejection port 8.
  • the nozzle plate 30 is made of metal, in which tapered ink ejection ports 8 each functioning as a nozzle are formed for the respective pressure chambers 10 of the cavity plate 22.
  • the ink passage 32 first extends upward from the sub-manifold channel 5a, then extends horizontally in the aperture 12, then further extends upward, then again extends horizontally in the pressure chamber 10, then extends obliquely downward in a certain length to get apart from the aperture 12, and then extends vertically downward toward the ink ejection port 8.
  • FIG. 10 is a lateral enlarged sectional view of the region enclosed with an alternate long and short dash line in FIG. 7.
  • the actuator unit 21 includes five piezoelectric sheets 41, 42, 43, 44, and 45 having the same thickness of about 15 ⁇ m. These piezoelectric sheets 41 to 45 are made into a continuous layered flat plate (continuous flat layers) that is so disposed as to extend over many pressure chambers 10 formed within one ink ejection region in the ink-jet head 1.
  • each of the piezoelectric sheets 41 to 45 is made of a lead zirconate titanate (PZT)-base ceramic material having ferroelectricity.
  • an about 2 ⁇ m-thick common electrode 34a is interposed between the uppermost piezoelectric sheet 41 of the actuator unit 21 and the piezoelectric sheet 42 neighboring downward the piezoelectric sheet 41.
  • the common electrode 34a is made of a single conductive sheet extending substantially in the whole region of the actuator unit 21. Also, between the piezoelectric sheet 43 neighboring downward the piezoelectric sheet 42 and the piezoelectric sheet 44 neighboring downward the piezoelectric sheet 43, an about 2 ⁇ m-thick common electrode 34b is interposed having the same shape as the common electrode 34a.
  • many pairs of common electrodes 34a and 34b each having a shape larger than that of a pressure chamber 10 so that the projection image of each common electrode projected along the thickness of the common electrode may include the pressure chamber may be provided for each pressure chamber 10.
  • many pairs of common electrodes 34a and 34b each having a shape somewhat smaller than that of a pressure chamber 10 so that the projection image of each common electrode projected along the thickness of the common electrode may be included in the pressure chamber may be provided for each pressure chamber 10.
  • the common electrode 34a or 34b may not always be a single conductive sheet formed on the whole of the face of a piezoelectric sheet. In the above modifications, however, all the common electrodes must be electrically connected with one another so that the portion corresponding to any pressure chamber 10 may be at the same potential.
  • an about 1 ⁇ m-thick individual electrode 35a is formed on the upper face of the piezoelectric sheet.41 at a position corresponding to the pressure chamber 10.
  • the individual electrode 35a has a nearly rhombic shape (length: 850 ⁇ m, width: 250 ⁇ m) in a plan view similar to that of the pressure chamber 10, so that a projection image of the individual electrode 35a projected along the thickness of the individual electrode 35a is included in the corresponding pressure chamber 10 (see FIG. 6).
  • an about 2 ⁇ m-thick individual electrode 35b having the same shape as the individual electrode 35a in a plan view is interposed at a position corresponding to the individual electrode 35a.
  • Electrode is provided between the piezoelectric sheet 44 and the piezoelectric sheet 45 neighboring downward the piezoelectric sheet 44, and on the lower face of the piezoelectric sheet 45.
  • Each of the electrodes 34a, 34b, 35a, and 35b is made of, e.g., an Ag-Pd-base metallic material.
  • the common electrodes 34a and 34b are grounded in a not-illustrated region. Thus, the common electrodes 34a and 34b are kept at the ground potential at a region corresponding to any pressure chamber 10.
  • the individual electrodes 35a and 35b in each pair corresponding to a pressure chamber 10 are connected to a driver IC 132 through an FPC 136 including leads independent of another pair of individual electrodes so that the potential of each pair of individual electrodes can be controlled independently of that of another pair(see FIGS. 2 and 3).
  • the individual electrodes 35a and 35b in each pair vertically arranged may be connected to the driver IC 132 through the same lead.
  • the piezoelectric sheets 41 to 43 are polarized in their thickness. Therefore, the individual electrodes 35a and 35b are set at a potential different from that of the common electrodes 34a and 34b to apply an electric field in the polarization, the portions of the piezoelectric sheets 41 to 43 to which the electric field has been applied works as active layers and the portions are ready to expand or contract in thickness, i.e., in layers, and to contract or expand perpendicularly to the thickness, i.e., in a plane, by the transversal piezoelectric effect.
  • the actuator unit 21 has a so-called unimorph structure in which the upper (i.e., distant from the pressure chamber 10) three piezoelectric sheets 41 to 43 are layers including active layers and the lower (i.e., near the pressure chamber 10) two piezoelectric sheets 44 and 45 are inactive layers.
  • the lowermost face of the piezoelectric sheets 41 to 45 is fixed to the upper face of partitions partitioning pressure chambers 10 formed in the cavity plate 22, as a result, the piezoelectric sheets 41 to 45 deform into a convex shape toward the pressure chamber side by contracting in a plane by the transversal piezoelectric effect (unimorph deformation). Therefore, the volume of the pressure chamber 10 is decreased to raise the pressure of ink. The ink is thereby ejected through the ink ejection port 8. After this, when the individual electrodes 35a and 35b are returned to the original potential, the piezoelectric sheets 41 to 45 return to the original flat shape and the pressure chamber 10 also returns to its original volume. Thus, the pressure chamber 10 sucks ink therein through the manifold channel 5.
  • all the individual electrodes 35a and 35b are set in advance at a different potential from that of the common electrodes 34a and 34b so that the piezoelectric sheets 41 to 45 deform into a convex shape toward the pressure chamber 10 side.
  • the corresponding pair of individual electrodes 35a and 35b is once set at the same potential as that of the common electrodes 34a and 34b.
  • the pair of individual electrodes 35a and 35b is again set at the different potential from that of the common electrodes 34a and 34b.
  • the piezoelectric sheets 41 to 45 return to their original shapes.
  • the corresponding pressure chamber 10 is thereby increased in volume from its initial state (the state that the potentials of both electrodes differ from each other), to suck ink from the manifold channel 5 into the pressure chamber 10.
  • the piezoelectric sheets 41 to 45 deform into a convex shape toward the pressure chamber 10.
  • the volume of the pressure chamber 10 is thereby decreased and the pressure of ink in the pressure chamber 10 increases to eject ink.
  • the piezoelectric sheets 41 to 45 deform into a concave shape toward the pressure chamber 10 by the transversal piezoelectric effect. Therefore, the volume of the pressure chamber 10 is increased to suck ink from the manifold channel 5. After this, when the individual electrodes 35a and 35b return to their original potential, the piezoelectric sheets 41 to 45 also return to their original flat shape. The pressure chamber 10 thereby returns to its original volume to eject ink through the ink ejection port 8.
  • the nozzle (the ink ejection port 8 at the tip end is illustrated in FIG. 6) connected with each pressure chamber 10 is not provided at the center of the pressure chamber 10 but deviated to one end.
  • a sub-manifold channel 5a that functions as a common ink passage is disposed so as to include the boundary region between first and second pressure chamber rows 11a and 11b in which nozzles are deviated on the opposite sides with respect to the arrangement direction A.
  • the width of the sub-manifold channel 5a can be made large. Therefore, even when the thickness (depth) of the sub-manifold channel 5a in the above third direction is fixed, the passage resistance of the sub-manifold channel 5a to ink is low, and so ink supply to the pressure chamber 10 can smoothly be performed.
  • the passage unit 4 includes apertures 12 extending substantially in parallel with the surface of the passage unit 4.
  • Each pressure chamber 10 is connected with the corresponding sub-manifold channel 5a through an aperture 12.
  • the number of sub-manifold channels 5a can be reduced.
  • the sub-manifold channel 5a must extend along each pressure chamber row 11a or 11b as illustrated in FIG. 6.
  • each pressure chamber 10 by connecting each pressure chamber 10 with the corresponding sub-manifold channel 5a through an aperture 12, since ink supply is possible even if the pressure chamber 10 is somewhat distant from the sub-manifold channel 5a when viewing in the third direction perpendicular to the surface of the passage unit 4, the sub-manifold channel 5a need not be provided for each pressure chamber row 11a or 11b.
  • the pressure chamber 10 can overlap the aperture 12 when viewing in the third direction.
  • high integration of pressure chambers 10 is possible and high-resolution image formation can be realized with an ink-jet head 1 having a relatively small occupation area.
  • first pressure chamber rows 11a and second pressure chamber rows 11b two by two by alternately arranging first pressure chamber rows 11a and second pressure chamber rows 11b two by two, the number of sub-manifold channels 5a can be reduced in comparison with the case of the below-described modification. Besides, by disposing one sub-manifold channel 5a for each two pressure chamber rows 11a and 11b neighboring each other, since the width of the sub-manifold channel 5a can be made large, the passage resistance is lower and ink supply can smoothly be performed.
  • each sub-manifold channel 5a can be determined within a range that neither too much nor too less ink can be supplied to each pressure chamber 10.
  • one sub-manifold channel 5a is disposed so as to extend near nozzles for each two pressure chamber rows 11a and 11b neighboring each other.
  • each sub-manifold channel 5a of this embodiment includes most parts of one first pressure chamber row 11a and one second pressure chamber row 11b neighboring each other so that the ink ejection ports 8 of the nozzles connected with the respective pressure chambers 10 face outward. Since the width of the sub-manifold channel 5a is thus increased within a range that the sub-manifold channel 5a does not overlap any nozzle and the ink ejection port 8 at the tip end of the nozzle, the passage resistance of the sub-manifold channel 5a can be lower to intend smooth ink supply.
  • the passage unit 4 is formed with nine sheet members 22 to 30 laminated each other and each having corresponding openings, the manufacture of the passage unit 4 is easy.
  • the increase in shift of each actuator unit 21 from the accurate position on the passage unit 4 is restricted, and both can accurately be positioned to each other. Therefore, as to even an individual electrodes 35a and 35b relatively apart from a mark, the individual electrodes 35a and 35b can not considerably be shifted from the predetermined position to the corresponding pressure chamber 10.
  • the actuator unit 21 since the piezoelectric sheets 41 to 43 are sandwiched by the common electrodes 34a and 34b and the individual electrodes 35a and 35b, the volume of each pressure chamber 10 can easily be changed by the piezoelectric effect. Besides, since the piezoelectric sheets 41 to 45 are made into a continuous layered flat plate (continuous flat layers), the actuator unit 21 can easily be manufactured.
  • the ink-jet head 1 has the actuator units 21 each having a unimorph structure in which the piezoelectric sheets 44 and 45 near each pressure chamber 10 are inactive and the piezoelectric sheets 41 to 43 distant from each pressure chamber 10 include active layers. Therefore, the change in volume of each pressure chamber 10 can be increased by the transversal piezoelectric effect. As a result, in comparison with an ink-jet head in which a layer including active portions is provided on the pressure chamber 10 side and a non-active layer is provided on the opposite side, lowering the voltage to be applied to the individual electrodes 35a and 35b and/or high integration of the pressure chambers 10 can be achieved.
  • each pressure chamber 10 can be made small in size. Besides, even in case of a high integration of the pressure chambers 10, a sufficient amount of ink can be ejected. Thus, a decrease in size of the head 1 and a highly dense arrangement of printing dots can be realized.
  • each actuator unit 21 has a substantially trapezoidal shape.
  • the actuator units 21 are arranged in two lines in a staggered shape so that the parallel opposed sides of each actuator unit 21 extend along the length of the passage unit 4, and the oblique sides of each neighboring actuator units 21 overlap each other in the width of the passage unit 4. Since the oblique sides of each neighboring actuator units 21 thus overlap each other, in the length of the ink-jet head 1, the pressure chambers 10 existing along the width of the passage unit 4 can compensate each other. As a result, with realizing high-resolution printing, a small-size ink-jet head 1 having a very narrow width can be realized.
  • the arrangement directions of pressure chambers 10 disposed in a matrix along the surface of the passage unit 4 are not limited to the arrangement directions A and B described in the above embodiment as far as they are along the surface of the passage unit 4.
  • the arrangement directions may be various.
  • FIG. 11 illustrates a modification of arrangement of pressure chambers 10 in the passage unit 4.
  • the modification of FIG. 11 differs from the embodiment of FIG. 6 in the angle 'theta' between the arrangement directions A and B.
  • the angle 'theta' of FIG. 11 is smaller than that of FIG. 6.
  • the modification of FIG. 11 differs from the embodiment of FIG. 6 also in the relation between the arrangement directions A and B and a direction along the longer diagonal of each rhombic region 10x.
  • the diagonal direction and the arrangement direction A form a larger angle than the arrangement directions A and B, differently from the embodiment of FIG. 6.
  • FIG. 12 illustrates another modification of arrangement of pressure chambers 10 in the passage unit 4, wherein one first pressure chamber row 11a and one second pressure chamber row 11b are alternately repeated.
  • a pressure chamber 10 constituting a second pressure chamber row 11b protrudes from the upper side of FIG. 12.
  • a pressure chamber 10 constituting another second pressure chamber row 11b protrudes from the lower side of FIG. 12.
  • pressure chambers 10 constituting first pressure chamber rows 11a protrude from the upper and lower sides of FIG. 12, respectively.
  • each sub-manifold channel 15a is small.
  • the width of each sub-manifold channel 15a is large in comparison with a case wherein no increase occurs in interval of ink ejection ports 8 for neighboring pressure chamber rows, such as a case wherein each pressure chamber row is constituted by pressure chambers 10 for each of which an ink ejection port 8 is deviated on one side along the longer diagonal of each rhombic region 10x, or a case wherein each pressure chamber row is constituted by pressure chambers 10 for each of which an ink ejection port 8 is disposed at the center of the pressure chamber 10. Therefore, the passage resistance of each sub-manifold channel 5a to ink is lowered and smooth ink supply to each pressure chamber 10 can be performed.
  • each pressure chamber 10 may not be rhombic but have another shape such as a parallelogram. Besides, the shape in a plan view of each pressure chamber 10 included in the region also may be changed into a proper shape such as a parallelogram. Further, each pressure chamber 10 may be slender along the pressure wave propagation direction though high integration of pressure chambers 10 can not be expected.
  • each pressure chamber 10 may communicate directly with the corresponding sub-manifold channel 5a not through an aperture 12 though this is not preferable from the viewpoint of ink ejection stabilization.
  • apertures 12 may be provided at the same level as pressure chambers 10 in the third direction perpendicular to the surface of the passage unit 4. In this case, however, since each pressure chamber 10 can not overlap any aperture 12 when viewing perpendicularly to the surface of the passage unit 4 (third direction), high integration of pressure chambers 10 can not be achieved.
  • each sub-manifold channel 5a preferably includes the most parts of pressure chamber rows 11a and 11b neighboring each other. But, it suffices if each sub-manifold channel 5a includes a boundary region between those lines.
  • each pressure chamber 10 may not be along a plane of the passage unit 4.
  • passage unit 4 may not be formed with laminated sheet members.
  • each of the piezoelectric sheets and electrodes is not limited to those described above, and it may be changed to another known material.
  • Each of the inactive layers may be made of an insulating sheet other than a piezoelectric sheet.
  • the number of layers including active layers, the number of inactive layers, etc., may be changed properly.
  • piezoelectric sheets as layers including active layers included in an actuator unit 21 are put in three or five layers in the above-described embodiment, piezoelectric sheets may be put in seven or more layers. In this case, the numbers of individual and common electrodes may properly be changed in accordance with the number of layered piezoelectric sheets.
  • each actuator unit 21 includes two layers of piezoelectric sheets as inactive layers in the above-described embodiment, each actuator unit 21 may include only one inactive layer. Alternatively, each actuator unit 21 may include three or more inactive layers as far as they do not hinder the expansion or contraction deformation of the actuator unit 21.
  • each actuator unit 21 of the above-described embodiment includes inactive layers on the pressure chamber side of layers including active layers, a layer or layers including active layers may be disposed on the pressure chamber 10 side of the inactive layers. Alternatively, no inactive layer may be provided. However, by providing the inactive layers 44 and 45 on the pressure chamber 10 side of the layers including active layers, it is expected to further improve the deformation efficiency of the actuator unit 21.
  • common electrodes are kept at the ground potential in the above-described embodiment, this feature is not limitative.
  • the common electrodes may be kept at any potential as far as the potential is in common to all pressure chambers 10.
  • trapezoidal actuator units 21 are arranged in two lines in a staggered shape. But, each actuator unit may not always be trapezoidal. Besides, actuator units may be arranged in a single line along the length of the passage unit. Alternatively, actuator units may be arranged in three or more lines in a staggered shape. Further, not one actuator unit 21 is disposed to extend over pressure chambers 10 but one actuator unit 21 may be provided for each pressure chamber 10.
  • each of the common electrodes 34a and 34b may not always be made of a single conductive sheet provided in the substantially whole region of each actuator unit 21. In such a case, however, the parts of each common electrode must be electrically connected with one another so that all the parts corresponding to the respective pressure chambers 10 are at the same potential.

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  • Particle Formation And Scattering Control In Inkjet Printers (AREA)
EP03003697A 2002-02-18 2003-02-18 Tête d'impression jet d'encre et imprimante l'utilisant Expired - Lifetime EP1336488B1 (fr)

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US7163280B2 (en) 2003-08-11 2007-01-16 Brother Kogyo Kabushiki Kaisha Ink-jet head, and ink-jet recording apparatus including the ink-jet head
EP1512533A1 (fr) * 2003-08-12 2005-03-09 Brother Kogyo Kabushiki Kaisha Tête jet d'encre
US9144967B2 (en) 2011-07-28 2015-09-29 Kyocera Corporation Piezoelectric actuator, liquid discharge head, and recording device

Also Published As

Publication number Publication date
EP2213456B1 (fr) 2013-10-23
CN1273298C (zh) 2006-09-06
DE60329430D1 (de) 2009-11-12
EP2213456A3 (fr) 2010-09-01
CN2677153Y (zh) 2005-02-09
EP2213456A2 (fr) 2010-08-04
CN1442299A (zh) 2003-09-17
EP1336488A3 (fr) 2003-11-05
EP1336488B1 (fr) 2009-09-30

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