JP2005186324A - Inkjet printer and inkjet head - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce a structural cross talk due to the distortion of a piezoelectric sheet which spreads as far as the positions of adjacent individual electrodes when a drive signal is inputted to the individual electrodes to deform the piezoelectric sheet. <P>SOLUTION: In this inkjet printer, an actuator unit 21 comprises a plurality of individual electrodes 35 to which the drive signal is supplied; a common electrode 34 fitted across a plurality of pressure chambers 10; a piezoelectric sheet which is sandwiched between the individual electrode 35 and the common electrode 34 and becomes deformed when the drive signal is supplied to the individual electrode 35; and a plurality of independent electrodes 60 installed correspondingly to each of the individual electrodes 35 in a non-opposite region, which is not opposed to at least the pressure chamber 10, of a region occupied by the piezoelectric sheet. When the drive signal is supplied to the specified individual electrode 35 resulting in the deformation of the piezoelectric sheet, a negative signal for negating the distortion of the piezoelectric sheet spreading as far as the position of the other adjacent individual electrode 35, is supplied to the independent electrode 60. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

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

  An ink jet head of an ink jet printer distributes ink supplied from an ink tank to a plurality of pressure chambers, and selectively applies a pulsed pressure to each pressure chamber, thereby supplying ink from nozzles communicating with each pressure chamber. Discharge. Here, as means for selectively applying pressure to the pressure chamber, there is an actuator unit including a plurality of laminated piezoelectric sheets made of piezoelectric ceramic.

  As such an actuator unit, for example, a plurality of individual electrodes that are arranged to face each of a plurality of pressure chambers and to which a drive signal for changing the volume of the pressure chamber is input, and a plurality of pressure chambers are provided. And a common electrode held at the ground potential and a piezoelectric sheet sandwiched between the individual electrode and the common electrode (see Patent Document 1). The portion of the piezoelectric sheet sandwiched between the individual electrode and the common electrode and polarized in the stacking direction is a so-called piezoelectric when the individual electrode is set to a potential different from that of the common electrode and an external electric field is applied in the polarization direction of the piezoelectric sheet. Deforms in the stacking direction due to the longitudinal effect. If the direction of the external electric field is the same as the direction of polarization, the piezoelectric sheet extends in the stacking direction. The volume of the pressure chamber fluctuates due to the deformation of the piezoelectric sheet, and ink can be ejected from the nozzle communicating with the pressure chamber toward the recording medium.

Japanese Patent Laid-Open No. 4-341852 (FIG. 1)

  However, in recent years, as pressure chambers are arranged with high density in order to meet the demand for higher resolution and high-speed printing of images, adjacent pressure chambers are caused by deforming a piezoelectric sheet facing a certain pressure chamber. The so-called structural crosstalk in which even the piezoelectric sheet facing the surface is deformed, ink is ejected from nozzles that should not eject ink, or the amount of ink ejected from the nozzles is increased or decreased from the original amount. Will occur.

  Due to this structural crosstalk, for example, when ink is ejected from a certain pressure chamber, the deformation amount of the piezoelectric sheet facing the certain pressure chamber differs depending on whether ink is ejected simultaneously from the adjacent pressure chamber. As a result, there is a problem that the amount of ink ejected from a certain pressure chamber is not stable.

  An object of the present invention is to reduce structural crosstalk due to distortion of a piezoelectric sheet extending to the position of an adjacent individual electrode when a piezoelectric sheet is deformed when a drive signal is input to an individual electrode.

Means for Solving the Problems and Effects of the Invention

  According to a first aspect of the invention, there is provided an ink jet printer in which a plurality of pressure chambers communicating with nozzles are arranged adjacent to each other in a matrix along a plane, and fixed to one surface of the flow channel unit, the pressure chambers An actuator unit that changes the volume of each of the plurality of individual electrodes, the actuator unit being disposed to face each of the plurality of pressure chambers, and supplied with a drive signal for changing the volume of the pressure chambers; A common electrode provided over a plurality of pressure chambers; a piezoelectric sheet sandwiched between the individual electrode and the common electrode; and deformed when a drive signal is supplied to the individual electrode; and the piezoelectric sheet A plurality of independent electrodes provided corresponding to each of the plurality of individual electrodes in a non-opposing region that does not face the pressure chamber in at least the region occupied by When the drive signal is supplied to the individual electrode and the piezoelectric sheet is deformed, a cancellation signal for canceling the distortion of the piezoelectric sheet reaching the position of the other adjacent individual electrode, corresponding to the predetermined individual electrode And a cancellation signal generating means for generating a cancellation signal supplied to the independent electrode.

  The portion of the piezoelectric sheet sandwiched between the individual electrode and the common electrode is such that when the drive signal is selectively input to the individual electrode and the individual electrode is set to a potential different from that of the common electrode, the polarization direction of the piezoelectric sheet It expands and contracts based on the difference from the applied direction of the electric field. Due to the deformation of the piezoelectric sheet, a pulsed pressure is applied to the pressure chamber, and ink is ejected from the nozzle communicating with the pressure chamber. However, along with the deformation of the piezoelectric sheet during ink ejection, the piezoelectric sheet is distorted (vibration of the piezoelectric sheet) to a position facing the adjacent pressure chamber, and structural crosstalk occurs. Therefore, in the present invention, when a drive signal is input to a certain individual electrode and the piezoelectric sheet is deformed, structural crosstalk is prevented by positively canceling the distortion of the piezoelectric sheet extending to the position of the adjacent individual electrode. Reduce.

  That is, a plurality of independent electrodes are provided corresponding to each of the plurality of individual electrodes in at least a non-facing region that does not face the pressure chamber in a region occupied by the piezoelectric sheet. When a drive signal is supplied to a predetermined individual electrode, a cancellation signal is generated by the cancellation signal generation means, and a cancellation signal is supplied to the independent electrode corresponding to the predetermined individual electrode. Then, the distortion of the piezoelectric sheet at the position of the predetermined individual electrode to which the drive signal is supplied extends to the position of the other individual electrode adjacent to the individual electrode and is applied to the predetermined individual electrode to which the cancellation signal is supplied. The distortion of the piezoelectric sheet at the position of the corresponding independent electrode also reaches the position of the other individual electrode adjacent to this individual electrode, and the two cancel each other. As a result, structural crosstalk can be reduced.

  An ink jet printer according to a second aspect is the ink jet printer according to the first aspect, wherein the individual electrode is drawn out to the non-opposing region from the main electrode portion opposed to the pressure chamber, and driven to the individual electrode. A contact portion to which a signal line for supplying a signal is connected, and the independent electrode is disposed in the vicinity of the contact portion in the non-facing region. When the contact portion is drawn from the main electrode portion to the non-opposing region, the distance from the contact portion to another adjacent individual electrode is shortened. The distortion of the piezoelectric sheet that reaches the individual electrodes increases. Therefore, by supplying a canceling signal to the independent electrode arranged in the vicinity of the contact portion, the distortion of the piezoelectric sheet extending from the contact portion to another adjacent individual electrode can be surely canceled.

  An ink jet printer according to a third aspect is the ink jet printer according to the second aspect, wherein the main electrode portion has a substantially rhombic planar shape, and the plurality of individual electrodes are substantially parallel to one side of the rhombus of the main electrode portion. Are arranged in a direction and a second direction substantially parallel to the other side adjacent to the one side, and the contact portion is drawn in parallel to the longitudinal direction from one end in the longitudinal direction of the main electrode portion, The independent electrode is provided near the other end in the longitudinal direction of the main electrode portion of another individual electrode adjacent to the corresponding individual electrode in the longitudinal direction. Therefore, it is possible to reliably cancel the distortion of the piezoelectric sheet that extends from the contact portion to which the drive signal is supplied to the positions of the other individual electrodes adjacent in two directions parallel to the two sides of the rhombus.

  The ink jet printer according to a fourth aspect is the ink jet printer according to the third aspect, wherein the contact portion of the individual electrode is adjacent to the individual electrode from the center thereof in the first direction and the second direction, respectively. The individual linear electrodes are arranged so that the first linear distances, which are the linear distances to the center of the main electrode portion, are equal to each other, and the independent electrodes corresponding to the individual electrodes are arranged from the center to the individual electrodes. And the second linear distance, which is a linear distance to the center of the main electrode portion of each of the two other individual electrodes adjacent to each other in the direction and the second direction, is arranged to be equal to each other. Is.

  Accordingly, with respect to the other two individual electrodes adjacent to the predetermined individual electrode, the distortion of the piezoelectric sheet from the contact portion of the predetermined individual electrode to which the drive signal is input is extended to an independent electrode corresponding to the predetermined individual electrode. The effect of canceling the distortion of the piezoelectric sheet when the canceling signal is supplied can be made equal, and the ink discharge characteristics (ink discharge speed, discharge amount, etc.) from the plurality of nozzles respectively communicating with the plurality of pressure chambers It can be made uniform.

  An ink jet printer according to a fifth aspect of the present invention is the ink jet printer according to the fourth aspect, wherein the second linear distance is shorter than the first linear distance. Since the second linear distance that is the distance from the independent electrode to the main electrode part of the adjacent individual electrode is shorter than the first linear distance that is the distance from the contact part to the main electrode part of the adjacent individual electrode, When the drive signal is input to the unit, the strength of the cancellation signal supplied to the independent electrode can be reduced, so that the power consumption when supplying the cancellation signal to the independent electrode can be kept low.

  An ink jet printer according to a sixth aspect of the present invention is the ink jet printer according to the first aspect, wherein the individual electrode has a main electrode portion opposed to the pressure chamber, and is electrically connected to the main electrode portion and opposed to the pressure chamber. The independent electrode is disposed around the main electrode portion in the non-facing region. As described above, when a contact portion electrically connected to the main electrode portion is provided at a position facing the pressure chamber, an independent electrode is disposed around the main electrode portion, thereby allowing adjacent It is possible to cancel the distortion of the piezoelectric sheet over the position of the individual electrodes.

  An ink jet printer according to a seventh invention is characterized in that, in the sixth invention, the main electrode portion is surrounded by the independent electrodes. By surrounding the individual electrode with the independent electrode, the distortion of the piezoelectric sheet extending to the position of the other adjacent individual electrode can be surely canceled.

  An ink jet printer according to an eighth aspect of the present invention is the ink jet printer according to any one of the first to seventh aspects, wherein the cancellation signal generation means includes cancellation signal supply means for supplying the cancellation signal to the plurality of independent electrodes. The signal supply means supplies the cancellation signal to the independent electrode corresponding to the predetermined individual electrode in synchronization with a drive signal supplied to the predetermined individual electrode. Thus, by supplying a cancellation signal to the independent electrode in synchronization with the drive signal, the distortion of the piezoelectric sheet extending to the position of the adjacent individual electrode is effectively canceled when the drive signal is supplied to the individual electrode. Can do.

  An ink jet printer according to a ninth aspect is the ink jet printer according to the eighth aspect, wherein the cancellation signal generating means is supplied to the predetermined individual electrode as a cancellation signal supplied to the independent electrode corresponding to the predetermined individual electrode. A signal having a phase opposite to that of the driving signal is generated. In this way, by supplying a signal having a phase opposite to that of the drive signal to the independent electrode as a cancellation signal, the distortion of the piezoelectric sheet extending to the position of the adjacent individual electrode when supplying the drive signal to the individual electrode is more effective. Can be counteracted.

  An ink jet printer according to a tenth aspect of the present invention is the ink jet printer according to the eighth or ninth aspect, wherein the cancellation signal supply means is configured to provide another signal adjacent to the predetermined individual electrode when a drive signal is supplied to the predetermined individual electrode. When the drive signal is simultaneously supplied to at least one of the individual electrodes, the cancellation signal is supplied to the independent electrode corresponding to the predetermined individual electrode, and the drive signal is supplied to the predetermined individual electrode In this case, when the drive signal is not supplied to all the other adjacent individual electrodes, the cancellation signal is not supplied to the independent electrode corresponding to the predetermined individual electrode.

  When a drive signal is supplied to a predetermined individual electrode, if the drive signal is supplied to another adjacent individual electrode and ink is ejected from the corresponding nozzle, it is adjacent from the position of the predetermined individual electrode. Since the ink ejection characteristics change when the piezoelectric sheet is strained to the position of the individual electrode, it is necessary to supply a cancellation signal to the independent electrode corresponding to the predetermined individual electrode in order to cancel the distortion of the piezoelectric sheet. There is. However, when the drive signal is not supplied to all other adjacent individual electrodes and ink is not ejected from the corresponding nozzle, even if the piezoelectric sheet is distorted, the influence is small. Therefore, in this case, by not supplying the cancellation signal to the independent electrode corresponding to the predetermined individual electrode, it is possible to suppress power consumption when supplying the cancellation signal to the independent electrode.

  An ink jet head according to an eleventh aspect of the invention includes a flow path unit in which a plurality of pressure chambers communicating with nozzles are arranged adjacent to each other in a matrix along a plane, and fixed to one surface of the flow path unit. An actuator unit that changes the volume of each of the plurality of individual electrodes, the actuator unit being disposed to face each of the plurality of pressure chambers, and supplied with a drive signal for changing the volume of the pressure chambers; A common electrode provided over a plurality of pressure chambers; a piezoelectric sheet sandwiched between the individual electrode and the common electrode; and deformed when a drive signal is supplied to the individual electrode; and the piezoelectric sheet A plurality of independent electrodes provided corresponding to each of the plurality of individual electrodes in a non-opposing region that does not face the pressure chamber in at least the region occupied by When the drive signal is supplied to the individual electrode and the piezoelectric sheet is deformed, a cancellation signal for canceling the distortion of the piezoelectric sheet reaching the position of the other adjacent individual electrode, corresponding to the predetermined individual electrode And a cancellation signal generating means for generating a cancellation signal supplied to the independent electrode.

  In the eleventh aspect of the invention, the canceling signal generating means for generating the canceling signal supplied to the independent electrode is provided in the ink jet head. However, the operation and effect thereof are the same as in the first aspect of the invention. The description is omitted.

  FIG. 1 is a schematic diagram of an ink jet printer according to a first embodiment of the present invention. An ink jet printer 101 shown in FIG. 1 is a color ink jet printer having four ink jet heads 1. The inkjet printer 101 includes a paper feeding unit 111 on the left side in the drawing and a paper discharge unit 112 on the right side in the drawing. Although not shown in FIG. 1, the inkjet printer 101 includes a control unit 113 (see FIG. 11) that controls various operations such as ejection of ink from the inkjet head 1.

  Inside the ink jet printer 101, a paper transport path is formed through which paper is transported from the paper feed unit 111 toward the paper discharge unit 112. A pair of feed rollers 105 a and 105 b that sandwich and convey a sheet as an image recording medium are disposed immediately downstream of the sheet feeding unit 111. The paper is fed from the left to the right in the figure by the pair of feed rollers 105a and 105b. Two belt rollers 106 and 107 and an endless conveyance belt 108 wound around the rollers 106 and 107 are disposed in the middle of the sheet conveyance path. The outer peripheral surface of the conveyor belt 108, i.e., the conveyor surface, is subjected to silicone treatment. While the sheet conveyed by the pair of feed rollers 105 a and 105 b is held on the conveyor surface of the conveyor belt 108 by its adhesive force, The belt roller 106 can be conveyed toward the downstream side (right side) by being driven to rotate clockwise (in the direction of arrow 104) in the drawing.

  The four inkjet heads 1 have a head body 70 at the lower end. The head main bodies 70 each have a rectangular cross section, and are arranged close to each other so that the longitudinal direction thereof is a direction perpendicular to the paper transport direction (the vertical direction in FIG. 1). That is, the printer 101 is a line printer. The bottom surfaces of the four head bodies 70 are opposed to the sheet conveyance path, and nozzles on which a large number of nozzles 8 having a minute diameter are formed are provided on these bottom surfaces. From the four head bodies 70, magenta, yellow, cyan and black inks are respectively ejected (see FIG. 5).

  The head main body 70 is disposed so that a small amount of gap is formed between the lower surface of the head main body 70 and the conveyance surface of the conveyance belt 108, and a sheet conveyance path is formed in the gap portion. With this configuration, when the paper transported on the transport belt 108 sequentially passes immediately below the four head bodies 70, each color ink is ejected from the nozzle toward the upper surface of the paper, that is, the printing surface. A desired color image can be formed on the paper.

  Next, the inkjet head 1 will be described in detail. As shown in FIGS. 2 and 3, the inkjet head 1 is disposed above a head body 70 having a rectangular planar shape extending in the main scanning direction for ejecting ink onto a sheet. And a base block 71 on which two ink reservoirs 3 are formed that are flow paths for the ink supplied to the head main body 70.

  The head body 70 includes a flow path unit 4 in which an ink flow path is formed, and a plurality of actuator units 21 bonded to the upper surface of the flow path unit 4. Both the flow path unit 4 and the actuator unit 21 are configured by laminating a plurality of thin plates and bonding them together. Further, a flexible printed circuit (FPC) 50, which is a power supply member, is bonded to the upper surface of the actuator unit 21 and pulled out to the left and right. The base block 71 is made of a metal material such as stainless steel. The ink reservoir 3 in the base block 71 is a substantially rectangular parallelepiped hollow region formed along the longitudinal direction of the base block 71.

  The lower surface 73 of the base block 71 protrudes downward from the periphery in the vicinity of the opening 3b. The base block 71 is in contact with the flow path unit 4 only in the portion 73a near the opening 3b of the lower surface 73. Therefore, a region other than the portion 73a near the opening 3b on the lower surface 73 of the base block 71 is separated from the head main body 70, and the actuator unit 21 is disposed in this separated portion.

  The base block 71 is bonded and fixed in a recess formed on the lower surface of the grip portion 72 a of the holder 72. The holder 72 includes a gripping portion 72a and a pair of flat projections 72b extending from the upper surface of the gripping portion 72a at a predetermined interval in a direction orthogonal thereto. The FPC 50 bonded to the actuator unit 21 is disposed along the surface of the protruding portion 72b of the holder 72 via an elastic member 83 such as a sponge. And driver IC80 is installed on FPC50 arrange | positioned on the protrusion part 72b surface of the holder 72. FIG. The FPC 50 is electrically joined to both by soldering so as to transmit the drive signal output from the driver IC 80 to the actuator unit 21 (described later in detail) of the head body 70.

  Since the heat sink 82 having a substantially rectangular parallelepiped shape is closely disposed on the outer surface of the driver IC 80, the heat generated in the driver IC 80 can be efficiently dissipated. A substrate 81 is disposed above the driver IC 80 and the heat sink 82 and outside the FPC 50. The upper surface of the heat sink 82 and the substrate 81 and the lower surface of the heat sink 82 and the FPC 50 are bonded by a seal member 84, respectively.

  An IC 80 connected thereto via the substrate 81 and the FPC 50 generates a pulse for driving the actuator unit 21 and supplies the generated pulse to the actuator unit 21, which will be described later (see FIG. 11). Is configured. The pulse generation device 200 is connected to a control unit 113 (see FIG. 11) of the inkjet printer 101, and based on a command from the control unit 113, each of the inkjet heads 1 corresponding to magenta, yellow, cyan, and black. Take control.

  4 is a plan view of the head main body 70 shown in FIG. In FIG. 4, the ink reservoir 3 formed in the base block 71 is virtually drawn with a broken line. The two ink reservoirs 3 extend in parallel with each other at a predetermined interval along the longitudinal direction of the head body 70. The two ink reservoirs 3 each have an opening 3a at one end, and are always filled with ink by communicating with an ink tank (not shown) through the opening 3a. A large number of openings 3b are provided in each ink reservoir 3 along the longitudinal direction of the head main body 70, and connect each ink reservoir 3 and the flow path unit 4 as described above. A large number of the openings 3 b are arranged close to each other along the longitudinal direction of the head body 70. A pair of openings 3b communicating with one ink reservoir 3 and a pair of openings 3b communicating with the other ink reservoir 3 are arranged in a staggered manner.

  In the area where the openings 3b are not arranged, a plurality of actuator units 21 having a trapezoidal planar shape are arranged in a staggered pattern in a pattern opposite to the pair of the openings 3b. The parallel opposing sides (upper side and lower side) of each actuator unit 21 are parallel to the longitudinal direction of the head body 70. Further, a part of the oblique sides of the adjacent actuator units 21 overlap in the width direction of the head main body 70.

  FIG. 5 is an enlarged view of a region surrounded by a one-dot chain line drawn in FIG. As shown in FIG. 5, the opening 3b provided in each ink reservoir 3 communicates with a manifold 5 which is a common ink chamber, and the tip of each manifold 5 branches into two to form a sub-manifold 5a. Yes. Further, in plan view, two sub-manifolds 5a branched from the adjacent openings 3b extend from the two oblique sides of the actuator unit 21, respectively. That is, below the actuator unit 21, a total of four sub-manifolds 5 a that are separated from each other extend along the parallel opposing sides of the actuator unit 21.

  The lower surface of the flow path unit 4 corresponding to the adhesion area of the actuator unit 21 is an ink ejection area. A large number of nozzles 8 are arranged in a matrix on the surface of the ink discharge area, as will be described later. In order to simplify the drawing, only a few of the nozzles 8 are depicted in FIG. 5, but in reality, they are arranged over the entire ink discharge region.

  FIG. 6 is an enlarged view of a region surrounded by a dashed line drawn in FIG. FIG. 6 shows a state in which a plane in which a large number of pressure chambers 10 in the flow path unit 4 are arranged in a matrix is viewed from a direction perpendicular to the ink ejection surface. Each pressure chamber 10 has a substantially rhombic planar shape with rounded corners, and the longer diagonal line is parallel to the width direction of the flow path unit 4. One end of each pressure chamber 10 communicates with the nozzle 8, and the other end communicates with the sub-manifold 5a serving as a common ink flow path via the aperture 12 (see FIG. 7). An individual electrode 35 similar to the pressure chamber 10 and having a slightly smaller planar shape than the pressure chamber 10 is formed on the actuator unit 21 at a position overlapping each pressure chamber 10 in plan view. In FIG. 6, only some of the large number of individual electrodes 35 are depicted for the sake of simplicity. 5 and 6, the pressure chambers 10 and the apertures 12 and the like that are to be drawn with broken lines in the actuator unit 21 or the flow path unit 4 are drawn with solid lines for easy understanding of the drawings.

  In FIG. 6, a plurality of virtual rhombus regions 10x each accommodating pressure chambers 10 are adjacently arranged in a matrix in two directions of arrangement direction A and arrangement direction B so as to share each side without overlapping each other. Has been. The arrangement direction A is the longitudinal direction of the inkjet head 1, that is, the extending direction of the sub-manifold 5a, and is parallel to the shorter diagonal line of the rhombic region 10x. The arrangement direction B is an oblique side direction of the rhombus region 10x that forms an obtuse angle θ with the arrangement direction A. The pressure chambers 10 are also arranged in the extending direction of other oblique sides adjacent to one oblique side of the rhombus region 10x. In FIG. 6, this arrangement direction is shown as an arrangement direction B '. The pressure chamber 10 has a common center position with the corresponding rhombus region 10x, and the contour lines of both are separated from each other in plan view.

  The pressure chambers 10 adjacently arranged in a matrix in two directions of the arrangement direction A and the arrangement direction B are separated along the arrangement direction A by a distance corresponding to 37.5 dpi. Further, 18 pressure chambers 10 are arranged in the arrangement direction B in one ink ejection region. However, the pressure chambers at both ends in the arrangement direction B are dummy and do not contribute to ink ejection.

  The plurality of pressure chambers 10 arranged in a matrix form a plurality of pressure chamber rows along the arrangement direction A shown in FIG. The pressure chamber rows, as viewed from the direction perpendicular to the paper surface of FIG. 6, correspond to the first pressure chamber row 11a, the second pressure chamber row 11b, and the third pressure depending on the relative position with respect to the sub-manifold 5a. It is divided into a chamber row 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. Has been placed.

  The pressure chambers 10a constituting the first pressure chamber row 11a and the pressure chambers 10b constituting the second pressure chamber row 11b are orthogonal to the arrangement direction A when viewed from the direction perpendicular to the paper surface of FIG. With respect to the direction, the nozzles 8 are unevenly distributed on the lower side in the drawing of FIG. And the nozzle 8 is located in the lower end part of the corresponding rhombus area | region 10x. On the other hand, in the pressure chambers 10c constituting the third pressure chamber row 11c and the pressure chambers 10d constituting the fourth pressure chamber row 11d, the nozzles 8 are unevenly distributed on the upper side in FIG. And the nozzle 8 is located in the upper end part of the corresponding rhombus area | region 10x, respectively. In the first and fourth pressure chamber rows 11a and 11d, when viewed from the direction perpendicular to the sheet of FIG. 6, more than half of the pressure chambers 10a and 10d overlap the sub-manifold 5a. In the second and third pressure chamber rows 11b and 11c, the entire region of the pressure chambers 10b and 10c does not overlap with the sub manifold 5a. Therefore, for the pressure chambers 10 belonging to any pressure chamber row, the width of the sub-manifold 5a is made as wide as possible while the nozzle 8 communicating therewith does not overlap the sub-manifold 5a, and ink is supplied to each pressure chamber 10. It can be supplied smoothly.

  Next, the cross-sectional structure of the head main body 70 will be further described with reference to FIGS. 7 is a cross-sectional view taken along line VII-VII in FIG. 6, and FIG. 8 is a partially exploded perspective view of the head body. As shown in FIG. 7, the nozzle 8 communicates with the sub-manifold 5 a through the pressure chamber 10 (10 a) and the aperture 12. In this manner, the individual ink flow paths 32 extending from the outlet of the sub-manifold 5 a to the nozzle 8 through the aperture 12 and the pressure chamber 10 are formed in the head main body 70 for each pressure chamber 10.

  As shown in FIG. 8, the head main body 70 includes the actuator unit 21, the cavity plate 22, the base plate 23, the aperture plate 24, the supply plate 25, the manifold plates 26, 27, 28, the cover plate 29, and the nozzle plate 30 from above. It has a laminated structure in which a total of 10 sheet materials are laminated. Among these, the flow path unit 4 is composed of nine metal plates excluding the actuator unit 21. Each metal plate is collectively joined by diffusion joining.

  As will be described in detail later, the actuator unit 21 is formed by stacking four piezoelectric sheets 41 to 44 (see FIG. 10) and arranging electrodes so that only the uppermost layer becomes an active layer when an electric field is applied. A layer having a portion (hereinafter simply referred to as “a layer having an active layer”), and the remaining three layers are inactive layers. The cavity plate 22 is a metal plate provided with a number of substantially diamond-shaped openings corresponding to the pressure chambers 10. The base plate 23 is a metal plate provided with a communication hole between the pressure chamber 10 and the aperture 12 and a communication hole from the pressure chamber 10 to the nozzle 8 for one pressure chamber 10 of the cavity plate 22. The aperture plate 24 is provided with a communication hole from the pressure chamber 10 to the nozzle 8 in addition to the aperture 12 formed by two etching holes and a half-etching region connecting the two holes with respect to one pressure chamber 10 of the cavity plate 22. It is a metal plate. The supply plate 25 is a metal plate provided with a communication hole between the aperture 12 and the sub-manifold 5 a and a communication hole from the pressure chamber 10 to the nozzle 8 for one pressure chamber 10 of the cavity plate 22. The manifold plates 26, 27, and 28 are connected to each other at the time of stacking, and in addition to the holes constituting the sub-manifold 5 a, each pressure chamber 10 of the cavity plate 22 has a communication hole from the pressure chamber 10 to the nozzle 8. Metal plate. The cover plate 29 is a metal plate provided with a communication hole from the pressure chamber 10 to the nozzle 8 for one pressure chamber 10 of the cavity plate 22. The nozzle plate 30 is a metal plate in which the nozzles 8 are provided for one pressure chamber 10 of the cavity plate 22. The nozzle 8 has a tapered shape in which the cross-sectional area decreases from the upper side to the lower side in the stacking direction.

  These nine metal plates are stacked in alignment with each other so that the individual ink flow paths 32 as shown in FIG. 7 are formed. The individual ink flow path 32 first extends upward from the sub-manifold 5a, extends horizontally at the aperture 12, then further upwards, extends horizontally again at the pressure chamber 10, and then moves away from the aperture 12 for a while. Head diagonally downward and then vertically downward toward nozzle 8

Next, the structure of the actuator unit 21 stacked on the uppermost cavity plate 22 in the flow path unit 4 will be described. As shown in FIGS. 9 and 10, the actuator unit 21 has the same thickness of about 15 μm. It includes four piezoelectric sheets 41, 42, 43, 44 formed as described above. These piezoelectric sheets 41 to 44 are continuous layered flat plates (continuous flat plate layers) so as to be disposed across a number of pressure chambers 10 formed in one ink discharge region in the head main body 70. . Since the piezoelectric sheets 41 to 44 are arranged as a continuous flat plate layer across a large number of pressure chambers 10, the individual electrodes 35 can be arranged on the piezoelectric sheet 41 with high density by using, for example, a screen printing technique. It has become. For this reason, the pressure chambers 10 formed at positions corresponding to the individual electrodes 35 can be arranged with high density, and high-resolution images can be printed. The piezoelectric sheets 41 to 44 are made of a lead zirconate titanate (PZT) ceramic material having ferroelectricity.

  On the uppermost piezoelectric sheet 41, individual electrodes 35 are formed. Between the uppermost piezoelectric sheet 41 and the lower piezoelectric sheet 42, a common electrode 34 having a thickness of about 2 μm formed on the entire surface of the sheet is interposed. Both the individual electrode 35 and the common electrode 34 are made of, for example, a metal material such as Ag—Pd.

  As shown in FIGS. 9 and 10, the individual electrode 35 has a thickness of approximately 1 μm and a substantially rhombic (parallelogram) main electrode portion 35 a that is substantially similar to the pressure chamber 10, and is drawn from the main electrode portion 35 a. And a land portion 35b (contact portion) to which a signal line for supplying a drive signal is connected, and the plurality of individual electrodes 35 are arranged in an arrangement direction C substantially parallel to one side of the rhombus of the main electrode portion, The arrangement direction C and the acute angle φ are arranged in an arrangement direction D substantially parallel to the other side adjacent to the one side, and arranged in a matrix along a plane. The arrangement directions C and D are parallel to the arrangement directions B and B ′ of FIG. The main electrode portion 35a faces the pressure chamber 10, and one of the acute angle portions of the substantially rhomboid main electrode portion 35a extends in the longitudinal direction of the main electrode portion 35a (the lower diagonal direction of the rhombus in FIG. 9). The land portion 35b is drawn from the acute angle portion to a non-opposing region (girder portion) that does not face the pressure chamber. The land portion 35b has a circular shape having a diameter of about 160 μm and is electrically connected to the main electrode portion 35a. The land portion 35b is made of, for example, gold containing glass frit, and is adhered on the surface of the extended portion of the individual electrode 35. Further, the land portion 35b is electrically joined to a contact provided on the FPC 50, and driving for driving the pressure chamber 10 from the driver IC (see FIGS. 2 and 3) to the main electrode portion 35a via the land portion 35b. A signal (driving pulse) is input.

  Furthermore, in a non-opposing region that does not oppose the pressure chamber 10 in the region occupied by the piezoelectric sheet 41, a plurality of independent electrodes 60 that are electrically insulated from the individual electrodes 35 correspond to each of the plurality of individual electrodes 35. Is provided. The independent electrode 60 has a circular shape having a diameter of approximately 160 μm, like the land portion 35b. The independent electrode 60 is provided in the vicinity of the upper end of the main electrode portion 35a of another individual electrode 35 adjacent to the longitudinal direction (vertical direction in FIG. 9) of the main electrode portion 35a of the corresponding individual electrode 35. And the land part 35b of the individual electrode 35 is a linear distance to the center of the main electrode part 35a of two other individual electrodes adjacent to the arrangement direction C and the arrangement direction D or the effective center at which the displacement becomes the largest. The first linear distances L1 are arranged so as to be equal to each other. On the other hand, the independent electrode 60 corresponding to the individual electrode 35 also has the center or displacement of the main electrode portion 35a of the two other individual electrodes 35 adjacent to each other. The second linear distance L2, which is the linear distance to the effective center that increases, is arranged to be equal to each other. Furthermore, the first linear distance L1 and the second linear distance L2 are equal.

  The common electrode 34 is grounded in a region not shown. As a result, the common electrode 34 is kept at the same ground potential in the regions corresponding to all the pressure chambers 10. In addition, the individual electrode 35 and the independent electrode 60 are drivers via the FPC 50 including a plurality of independent lead wires for each individual electrode 35 and each independent electrode 60 so that the potential can be controlled independently. It is connected to the IC 80 (see FIGS. 2 and 3). Then, when a drive pulse is supplied to the corresponding individual electrode 35, a cancel pulse (a cancel signal) for canceling the distortion of the piezoelectric sheet 41 extending to the position of the other adjacent individual electrode 35 is applied to the independent electrode 60. Supplied. The supply of the cancellation pulse to the independent electrode 60 will be described in detail later.

  Next, a method for driving the actuator unit 21 will be described. The polarization direction of the piezoelectric sheet 41 in the actuator unit 21 is the thickness direction. That is, the actuator unit 21 uses one piezoelectric sheet 41 on the upper side (the side opposite to the pressure chamber 10) as the active layer and three piezoelectric sheets 42 to 44 on the lower side (the pressure chamber 10 side). It has a so-called unimorph type configuration as an inactive layer. Therefore, when the individual electrode 35 has a predetermined positive or negative potential, for example, if the electric field and polarization are in the same direction (hereinafter, this predetermined potential is referred to as the same potential), an electric field applied between the electrodes in the piezoelectric sheet 41 is applied. The portion works as an active layer and shrinks in a direction perpendicular to the polarization direction due to the piezoelectric transverse effect. On the other hand, since the piezoelectric sheets 42 to 44 are not affected by the electric field and do not spontaneously shrink, the piezoelectric sheets 42 to 44 are not contracted in a direction perpendicular to the polarization direction between the upper piezoelectric sheet 41 and the lower piezoelectric sheets 42 to 44. A difference is caused in the distortion, and the entire piezoelectric sheets 41 to 44 try to be deformed so as to protrude toward the non-active side (unimorph deformation). At this time, as shown in FIG. 10, the lower surfaces of the piezoelectric sheets 41 to 44 are fixed to the upper surface of the cavity plate 22 that partitions the pressure chamber 10. Deforms to become convex. For this reason, the volume of the pressure chamber 10 decreases, and the ink pressure increases. When the electric potential of the individual electrode 35 is changed so that the electric field and the polarization are in opposite directions (hereinafter, the changed electric potential is referred to as the reverse electric potential), the piezoelectric sheets 41 to 44 are convex on the active side. As a result, the ink pressure drops.

  The actuator unit 21 sets the individual electrode 35 to the same potential V1 in advance, and once sets the individual electrode 35 to the reverse potential V2 every time there is a discharge request, and then returns to the same potential V1 at a predetermined timing. In this case, since the pressure of the ink in the pressure chamber 10 decreases at the timing when the individual electrode 35 becomes the reverse potential V2, the ink is sucked into the pressure chamber 10 from the manifold 5 side. Thereafter, the ink pressure in the pressure chamber 10 rises at the timing when the individual electrode 35 is set to the same potential V <b> 1 again, and ink is ejected from the nozzle 8 communicating with the pressure chamber 10. That is, when ink is ejected from the nozzles 8, a rectangular-wave drive pulse (see FIGS. 12A, 13 A, and 14 A) is supplied to the corresponding individual electrode 35. . This pulse width is AL (Acoustic Length) which is the time length for the pressure wave to propagate from the manifold 5 to the nozzle 8 in the pressure chamber 10. When the inside of the pressure chamber 10 is reversed from the negative pressure state to the positive pressure state, the potential of the individual electrode 35 is set to the same potential again. Can be discharged.

  By the way, when a driving pulse is input to the individual electrode 35 corresponding to a certain pressure chamber 10, the piezoelectric sheet 41 facing the adjacent pressure chamber 10 is deformed due to the deformation of the piezoelectric sheet 41 facing the pressure chamber 10. Even so, so-called structural crosstalk occurs in which ink is ejected from the nozzles 8 that should not eject ink or the amount of ink ejection increases or decreases from the original amount. In the inkjet head 1 of the present embodiment, a plurality of pressure chambers 10 are arranged adjacent to each other in a matrix along a plane, and the separation distance between the adjacent pressure chambers 10 is short. It is easy to receive. In particular, as shown in FIG. 9, the land portion 35b of the individual electrode 35 is drawn out from the acute angle portion of the main electrode portion 35a to the non-facing region that does not face the pressure chamber 10, so that the land portion 35b The distance between two adjacent pressure chambers 10 is shortened so as to sandwich the land portion 35b. Therefore, the adverse effect due to the structural crosstalk is particularly great on the two pressure chambers 10 having such a positional relationship with the land portion 35b.

  Therefore, in the inkjet printer 101 of the present embodiment, a driving pulse (driving signal) is supplied from a pulse generating device 200 described below to a predetermined individual electrode 35 (35A: see FIG. 9), and the piezoelectric sheet 41 is deformed. Sometimes, the pulse generation device 200 supplies a cancellation pulse (cancellation signal) to the independent electrode 60 corresponding to the predetermined individual electrode 35 (35A), so that the individual electrodes adjacent to the arrangement direction B and the arrangement direction C are provided. The distortion of the piezoelectric sheet 41 extending to the position 35 (35B, 35C) (vibration of the piezoelectric sheet 41) is positively canceled to reduce structural crosstalk.

  Hereinafter, functions of the pulse generation device 200 including the substrate 81 and the driver IC 80 will be described in detail. Each functional unit of the pulse generation device 200 illustrated in FIG. 11 stores a CPU (Central Processing Unit) that is an arithmetic processing device mounted on the substrate 81, a program executed by the CPU, and data used for the program. This is realized by the function of a ROM (Read Only Memory), a RAM (Random Access Memory) for temporarily storing data during program execution, and each circuit configured in the driver IC 80.

  The pulse generation device 200 includes a communication unit 201, a storage unit 202, a drive pulse determination unit 203, a cancellation pulse determination unit 204, a drive pulse supply unit 205, and a cancellation pulse supply unit 206. The communication unit 201 communicates with the control unit 113 that controls the entire inkjet printer 101. The control unit 113 obtains image data expressed in gradations to be printed, separated into magenta, yellow, cyan, and black, and timing data for printing an image at a predetermined position on the sheet based on the image data. It transmits with respect to the pulse generation apparatus 200 of the inkjet head 1 corresponding to each color. The communication unit 201 receives the image data and the timing data, and stores them in the storage unit 202 so that they can be referred to from other functions.

  The storage unit 202 includes a ROM and a RAM, and includes a drive pulse pattern storage unit 202a, a cancellation pulse pattern storage unit 202b, and an image data storage unit 202c. The two pulse pattern storage units 202a and 202b are each composed of a ROM. Among them, the drive pulse pattern storage unit 202a stores the pulse pattern data of the drive pulse corresponding to each gradation data supplied to the individual electrode 35, while the cancellation pulse pattern storage unit 202b is an independent electrode 60. The pulse pattern data of the canceling pulse supplied to is stored. The image data storage unit 202c is configured by a RAM, and temporarily stores the image data and timing data received from the control unit 113.

  The pulse pattern is a group of concave rectangular wave pulses, and is determined by the number of ink droplets calculated from the three levels of ink ejection determined based on the gradation data, and the phase and cycle of the pulse pattern. Specifically, in the pulse pattern, a rectangular wave having a width of AL determined by the falling timing and the rising timing is continuous at intervals of AL in accordance with the number of ejected ink droplets (1 to 3). Finally, a rectangular wave having a half width of AL is added. The last rectangular wave is for generating a pressure for canceling the pressure remaining in the pressure chamber 10 (cancellation wave), and this cancel wave is added to the drive pulse pattern storage unit 202a. Pulse pattern data is stored. FIG. 12A shows a drive pulse pattern when the number of ejected ink droplets is 3, and FIG. 13A shows a drive pulse pattern when the number of ejected ink droplets is 2. FIG. ) Shows a drive pulse pattern when the number of ejected ink droplets is one.

  On the other hand, the cancellation pulse pattern storage unit 202b corresponds to three types of drive pulse patterns (see FIGS. 12A, 13A, and 14A) corresponding to the number of ink droplets, respectively. Three types of cancellation pulse patterns having an opposite phase relationship to each drive pulse pattern are stored in a state associated with the drive pulse pattern. 12B shows a cancellation pulse pattern when the number of ejected ink droplets is 3, FIG. 13B shows a cancellation pulse pattern when the number of ejected ink droplets is 2, and FIG. ) Shows a cancellation pulse pattern when the number of ejected ink droplets is one.

  The drive pulse determination unit 203 determines the pulse pattern of the drive pulse supplied to the individual electrode 35. Here, the drive pulse is determined by the pulse pattern for each number of ink droplets stored in the drive pulse pattern storage unit 202a, and the image data and timing data stored in the image data storage unit 202c. Specifically, for each pixel of the image data, it is determined from the timing data which nozzle 8 the pixel corresponds to, and the gradation data of the pixel is read and the pulse pattern data corresponding to this is read as the driving pulse. The pulse pattern is selected from the pulse patterns stored in the pattern storage unit 202a.

  The cancellation pulse determination unit 204 selects a pulse pattern corresponding to the drive pulse pattern of the drive pulse determined by the drive pulse determination unit 203 from the pulse patterns stored in the cancellation pulse pattern storage unit 202b. A cancellation pulse having a phase opposite to that of the driving pulse is determined.

  The drive pulse supply unit 205 generates the drive pulse determined by the drive pulse determination unit 203 and supplies the generated drive pulse to the individual electrode 35. On the other hand, the cancellation pulse supply unit 206 generates a cancellation pulse having a phase opposite to that of the drive pulse determined by the cancellation pulse determination unit 204, and supplies the generated cancellation pulse to the independent electrode 60 in synchronization with the drive pulse. . In this way, the cancellation pulse having the opposite phase to the drive pulse is supplied from the cancellation pulse supply unit 206 to the independent electrode in synchronization with the drive pulse, so that the drive pulse is applied to the land portion 35b of the predetermined individual electrode 35 (35A). When supplied, since the distortion of the piezoelectric sheet 41 induced by the independent electrode 60 overlaps with the distortion of the piezoelectric sheet 41 extending to the position of the adjacent individual electrode 35 (35B, 35C), it is predetermined. Crosstalk to the adjacent pressure chamber due to the input of the drive pulse to the individual electrode 35 can be effectively suppressed.

  In the above description, the communication unit 201, the storage unit 202, the cancellation pulse determination unit 204, and the cancellation pulse supply unit 206 correspond to cancellation signal generation means. The cancellation pulse supply unit 206 corresponds to a cancellation signal supply unit.

Next, the operation of the pulse generator 200 will be described with reference to the flowchart of FIG. The following description relates to processing for determining whether to supply drive pulses or cancellation pulses to all the individual electrodes 35 and independent electrodes 60 of the inkjet head 1 at a certain ink ejection timing. Si (i = 10, 11,...) Indicates a step.
The pulse generation device 200 is in a state of waiting for reception of image data and timing data transmitted from the control unit 113 when the ink jet printer 101 is turned on.

  When the image data and the timing data are transmitted from the control unit 113, the communication unit 201 receives the transmitted image data and timing data (S10). Then, the communication unit 201 stores the received image data and timing data in the image data storage unit 202c so that they can be referred to from other unit functions.

  Next, in S11, based on the image data and timing data stored in the image data storage unit 202c, it is sequentially determined whether each nozzle 8 is a nozzle that ejects ink. When the focused nozzle 8 is not a discharge nozzle (S11: No), the process proceeds to S14. When the focused nozzle 8 is an ejection nozzle (S11: Yes), the process proceeds to S12, and the drive pulse determination unit 203 corresponds to the nozzle 8 based on the gradation data of the image data corresponding to the nozzle 8. A drive pulse to be supplied to the individual electrode 35 is selected from the pulse patterns stored in the drive pulse pattern storage unit 202a and determined, and data of the determined drive pulse pattern is included in the drive pulse supply unit 205. The register is stored in association with the address of the nozzle 8 to complete preparation for generating the drive pulse.

  Further, the process proceeds to S13, and the cancellation pulse determination unit 204 determines the cancellation pulse supplied to the independent electrode 60 corresponding to the individual electrode 35 from the pulse patterns stored in the cancellation pulse storage unit 202b in S12. The pulse pattern corresponding to the drive pulse pattern of the selected drive pulse is selected and determined, and the data of the determined cancellation pulse pattern is stored in the register unit (not shown) included in the cancellation pulse supply unit 206 in association with the address of the nozzle 8. Then, preparation for generating the cancellation pulse is completed.

  If there is a next nozzle for which the pulse pattern has not been determined (S14: Yes), the process returns to S11 and the same process is repeated. If there is no next nozzle (S14: No), the process proceeds to S15.

  In S15, the drive pulse determined by the drive pulse determination unit 203 is generated by the drive pulse supply unit 205, the cancellation pulse determined by the cancellation pulse determination unit 204 is generated by the cancellation pulse supply unit 206, and further The pulse and the cancellation pulse are synchronized and supplied to the individual electrode 35 and the independent electrode 60 corresponding to the individual electrode 35, respectively.

  According to the inkjet printer 101 described above, when a drive pulse is supplied to a predetermined individual electrode 35, the cancellation pulse determined by the cancellation pulse determination unit 204 in synchronization with this is not opposed to the pressure chamber 10. It is supplied to an independent electrode 60 provided corresponding to the individual electrode 35 in the opposing region. Therefore, since the distortion of the piezoelectric sheet 41 extending to the position of the other individual electrode 35 (35B, 35C) adjacent to the predetermined individual electrode 35 (35A) is canceled by the cancellation pulse supplied to the independent electrode 60, the structural cross Talk can be reduced. For example, when ink is ejected from the pressure chamber 10 facing the individual electrode 35 (35B, 35C), ink is simultaneously ejected from the pressure chamber 10 facing the individual electrode 35 (35A) adjacent thereto. When ink is not ejected, the difference in deformation amount of the piezoelectric sheet 41 corresponding to the individual electrode 35 (35B, 35C) can be reduced, and the ink ejection amount can be stabilized.

  Furthermore, the distance (first linear distance L1) from the land portion 35b of the individual electrode 35 (35A) to which the drive pulse is supplied to the adjacent individual electrode 35 (35B, 35C), and the individual electrode adjacent from the independent electrode 60 35 (35B, 35C) is equal to the distance (second linear distance L2). Therefore, the effect of canceling the distortion of the piezoelectric sheet 41 when the cancellation pulse is supplied to the independent electrode 60 corresponding to the predetermined individual electrode 35 (35A) can be made equal, and a plurality of pressure chambers 10 communicate with each other. Ink ejection characteristics (ink ejection speed, ejection amount, etc.) from the nozzles 8 can be made uniform. Further, the cancellation pulse supplied to the independent electrode 60 has an opposite phase to the drive pulse supplied to the land portion 35b. Furthermore, the drive pulse and the cancellation pulse are supplied to the individual electrode 35 and the independent electrode 60 in synchronization with each other. Therefore, when the drive pulse is supplied to the land portion 35b, the distortion of the piezoelectric sheet 41 reaching the position of the adjacent individual electrode 35 (35B, 35C) can be effectively suppressed, and structural crosstalk can be prevented. It can be reliably reduced.

  As shown in FIG. 16, the distance (first linear distance L1) from the land portion 35b of the individual electrode 35 (35A) to the individual electrodes 35 (35B, 35C) adjacent in the arrangement direction C and the arrangement direction D is as follows. The independent electrode 60 may be arranged to be larger than the distance (second linear distance L2) from the independent electrode 60 to the adjacent individual electrode 35 (35B, 35C). In this case, when a drive pulse is supplied to the land portion 35b, a cancel pulse supplied to the independent electrode 60 in order to cancel the distortion of the piezoelectric sheet 41 reaching the position of the adjacent individual electrode 35 (35B, 35C). Can be made weaker than the driving pulse supplied to the land portion, so that the power consumption when the cancellation pulse is supplied to the independent electrode 60 can be kept low. In this case, it is preferable that the cancellation pulse is not a pulse having a completely opposite phase to the driving pulse, but a pulse whose amplitude and period are appropriately changed according to the difference between the distances L1 and L2. Further, the independent electrode 60 is located at an intermediate position between straight lines connecting the centers of the two individual electrodes 35 (35B, 35C) adjacent to each other so that the independent electrode 60 sandwiches the corresponding land portion 35b. This is preferable from the viewpoint of reducing the power consumption when supplying the cancellation pulse.

In addition, the independent electrode 60 does not need to be disposed only in the non-opposing region that does not face the pressure chamber 10. 10 may be arranged so as to extend to a facing region facing 10, and the shape, size, thickness, or the like can be freely set. In order to reduce the types of cancellation pulses prepared in advance, it is preferable that the shapes and sizes of all the independent electrodes 60 be the same.
Further, the pulse generation device 200 illustrated in FIG. 11 may be provided on the control unit 113 side of the inkjet printer 101.

  Next, a second embodiment of the present invention will be described. In the first embodiment described above, when a drive pulse is supplied to the individual electrode 35 (35A), a cancellation pulse is always supplied to the independent electrode 60 corresponding to the individual electrode 35 (35A). However, when the drive pulse is not supplied to the other individual electrode 35 (35B, 35C) adjacent to the individual electrode 35 (35A) and ink is not ejected from the corresponding nozzle 8, the other individual electrode 35 adjacent to the individual electrode 35 (35A) is not supplied. Even if the distortion of the piezoelectric sheet 41 reaches the position (35B, 35C), there is no problem as long as the distortion does not eject ink, and the adverse effect of structural crosstalk is small.

  Accordingly, when a drive pulse is supplied to a predetermined individual electrode 35 (35A), when a drive pulse is not supplied to the other individual electrode 35 (35B, 35C) adjacent thereto, the individual electrode 35 (35A) is handled. The cancellation pulse may not be supplied to the independent electrode 60. That is, as shown in FIG. 17, the image data is received (S20), and in the next S21, the data stored in the image data storage unit 202c is stored in the same manner as in S11 of the first embodiment (see FIG. 15). Based on this, it is determined in turn whether each nozzle 8 ejects ink.

  When there is no image data in the nozzle 8 of interest and the nozzle 8 is not a discharge nozzle (S21: No), the individual electrode 35 of the nozzle 8 of interest and the independent electrode 60 corresponding to the individual electrode 35 are used. The process proceeds to S25 without determining the drive pulse and the cancel pulse. On the other hand, when it is determined that the nozzle 8 is a discharge nozzle (S21: Yes), the process proceeds to S22, and the drive pulse determination unit 203 drives the same as in S12 of the first embodiment (see FIG. 15). The pulse is determined and stored in a register unit (not shown) of the drive pulse supply unit 205 to complete preparation for generating the drive pulse.

  Further, the process proceeds to S23, and it is determined whether or not at least one of the nozzles 8 adjacent to the target nozzle 8 determined as the discharge nozzle in S21 is a discharge nozzle. This determination is made by referring to the image data received in S20 and stored in the image data storage unit 202c. Here, when at least one of the adjacent nozzles 8 is a discharge nozzle (S23: Yes), the process proceeds to the next S24. In S24, similarly to S13 in the first embodiment (see FIG. 15), the cancellation pulse determination unit 204 selects and determines a cancellation pulse pattern corresponding to the drive pulse pattern determined in S22, and this determination is performed. The cancellation pulse pattern data is stored in the register unit of the cancellation pulse supply unit 206 to complete preparation for generation of the cancellation pulse. On the other hand, when all of the adjacent nozzles 8 are non-ejection nozzles (S23: No), the process proceeds to S25 without determining a cancellation pulse for the independent electrode 60 corresponding to the nozzle 8 of interest.

  In S25, if there is the next nozzle 8 for which the pulse pattern has not been determined (S25: Yes), the process returns to S21 again to determine the drive pulse pattern and the canceling pulse pattern corresponding thereto, and preparing for each pulse generation. Do. On the other hand, if preparation for pulse generation is completed for all the target nozzles 8 (S25: No), the process proceeds to S26. In S26, similarly to the embodiment S15 (see FIG. 15), the drive pulse and the cancellation pulse are generated by the pulse supply units 205 and 206, and are supplied to the individual electrode 35 and the independent electrode 60 in synchronization (S26). ). When the adjacent nozzle 8 is not a discharge nozzle (S23: No), the cancellation pulse determination unit 204 does not determine a cancellation pulse, and therefore the cancellation pulse is not supplied from the cancellation pulse supply unit 206 to the independent electrode 60 (S26).

  In this way, when no drive pulse is supplied to the other adjacent individual electrodes 35 (35B, 35C) and ink is not ejected from the nozzle 8, the cancellation pulse supply unit 206 corresponds to the predetermined individual electrode 35 (35A). By not supplying a cancellation signal to the independent electrode 60, the power consumption when supplying the cancellation pulse to the independent electrode 60 can be suppressed.

  Next, a third embodiment of the present invention will be described. As shown in FIG. 18, in the individual electrode 85 of the third embodiment, the land portion 85 b is disposed on the main electrode portion 85 a facing the pressure chamber 10. In such a case, the independent electrode 90 corresponding to the individual electrode 85 is arranged around the main electrode portion 85a in the non-opposing region not facing the pressure chamber 10 (particularly, the main electrode portion adjacent to the arrangement direction C and the arrangement direction D). (Around the portion having the shortest distance to 85a), the distortion of the piezoelectric sheet 41 extending to the position of another adjacent individual electrode 85 can be canceled. The land portion 85b may not necessarily be provided on the main electrode portion 85a as long as the land portion 85b is provided at a position facing the pressure chamber 10. Furthermore, as shown in FIG. 19, if the periphery of the main electrode portion 85a is completely surrounded by the independent electrode 91, the distortion of the piezoelectric sheet 41 extending to the position of the other adjacent individual electrode 85 can be canceled more reliably. Can do. The independent electrodes 90 and 91 may extend from a non-opposing region that does not face the pressure chamber 10 to a facing region that faces the pressure chamber 10.

  In the embodiment described above, the cancellation pulse determination unit 204 selects a pattern corresponding to the pulse pattern determined by the drive pulse determination unit 203 from the cancellation pulse pattern storage unit 202b. Similar to the unit 203, the cancellation pulse may be determined based on the image data and timing data stored in the image data storage unit 202c.

1 is a schematic configuration diagram of an inkjet printer according to a first embodiment of the present invention. It is a perspective view of an inkjet head. It is the III-III sectional view taken on the line of FIG. It is a top view of a head body. It is an enlarged view of the area | region enclosed with the dashed-dotted line of FIG. It is an enlarged view of the area | region enclosed with the dashed-dotted line of FIG. It is the VII-VII sectional view taken on the line of FIG. It is a partial exploded perspective view of a head body. It is an enlarged plan view of an actuator unit. FIG. 10 is a sectional view taken along line XX in FIG. 9. It is a functional block diagram of a pulse generation device. (A) is a waveform diagram of a drive pulse (the number of ink droplets is 1), and (b) is a waveform diagram of a cancellation pulse corresponding to the drive pulse. (A) is a waveform diagram of a drive pulse (the number of ink droplets is 2), and (b) is a waveform diagram of a cancellation pulse corresponding to the drive pulse. (A) is a waveform diagram of a drive pulse (the number of ink droplets is 2), and (b) is a waveform diagram of a cancellation pulse corresponding to the drive pulse. It is a flowchart which shows operation | movement of a pulse generation apparatus. It is an enlarged plan view of an actuator unit in a modified form of the first embodiment. It is a flowchart which shows operation | movement of the pulse generation apparatus in 2nd Embodiment. It is an enlarged plan view of an actuator unit in the third embodiment. It is an enlarged plan view of an actuator unit in a modified form of the third embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Inkjet head 8 Nozzle 10 Pressure chamber 21 Actuator unit 34 Common electrode 35 Individual electrode 35a Main electrode part 35b Land part 41 Piezoelectric sheet 60 Independent electrode 80 Driver IC
81 Substrate 85 Individual electrode 85a Main electrode part 85b Land part 90, 91 Independent electrode 101 Inkjet printer 200 Pulse generation device 201 Communication part 202 Storage part 204 Cancel pulse determination part 206 Cancel pulse supply part

Claims (11)

A flow path unit in which a plurality of pressure chambers communicating with the nozzle are arranged adjacent to each other in a matrix along a plane; and an actuator unit fixed to one surface of the flow path unit to change the volume of the pressure chamber. Prepared,
The actuator unit is
A plurality of individual electrodes that are arranged to face each of the plurality of pressure chambers and are supplied with a drive signal for changing the volume of the pressure chamber;
A common electrode provided over a plurality of pressure chambers;
A piezoelectric sheet sandwiched between the individual electrodes and the common electrode and deformed when a drive signal is supplied to the individual electrodes;
A plurality of independent electrodes provided corresponding to each of the plurality of individual electrodes in a non-opposing region that does not oppose at least the pressure chamber in a region occupied by the piezoelectric sheet;
When the drive signal is supplied to a predetermined individual electrode and the piezoelectric sheet is deformed, a cancellation signal for canceling the distortion of the piezoelectric sheet extending to the position of the other adjacent individual electrode, which is applied to the predetermined individual electrode. Cancellation signal generating means for generating a cancellation signal supplied to the corresponding independent electrode;
An ink jet printer comprising: The individual electrode includes a main electrode portion that faces the pressure chamber, and a contact portion that is drawn from the main electrode portion to the non-facing region and is connected to a signal line that supplies the drive signal to the individual electrode. ,
The inkjet printer according to claim 1, wherein the independent electrode is disposed in the vicinity of the contact portion in the non-facing region. The main electrode portion has a substantially rhombic planar shape, and a plurality of individual electrodes are in a first direction substantially parallel to one side of the rhombus of the main electrode portion, and a second substantially parallel to the other side adjacent to the one side. Are arranged in the direction of
The contact portion is drawn out in parallel to the longitudinal direction from one end in the longitudinal direction of the main electrode portion,
The inkjet according to claim 2, wherein the independent electrode is provided in the vicinity of the other end in the longitudinal direction of the main electrode portion of another individual electrode adjacent to the corresponding individual electrode in the longitudinal direction. Printer. The contact portion of the individual electrode is a linear distance from the center to the center of the main electrode portion of two other individual electrodes adjacent to the individual electrode in the first direction and the second direction, respectively. Arranged so that the linear distances of 1 are equal to each other,
The independent electrode corresponding to the individual electrode is a linear distance from the center to the center of the main electrode portion of two other individual electrodes adjacent to the individual electrode in the first direction and the second direction, respectively. The inkjet printer according to claim 3, wherein the second linear distances are arranged to be equal to each other.   The inkjet printer according to claim 4, wherein the second linear distance is shorter than the first linear distance. The individual electrode has a main electrode portion facing the pressure chamber, and a contact portion electrically connected to the main electrode portion and disposed facing the pressure chamber,
The inkjet printer according to claim 1, wherein the independent electrode is disposed around the main electrode portion in the non-facing region.   The inkjet printer according to claim 6, wherein the main electrode portion is surrounded by the independent electrode. The cancellation signal generation means includes cancellation signal supply means for supplying the cancellation signal to the plurality of independent electrodes,
The cancellation signal supply means supplies the cancellation signal to the independent electrode corresponding to the predetermined individual electrode in synchronization with a drive signal supplied to the predetermined individual electrode. 8. The inkjet printer according to any one of items 7.   The cancellation signal generating means generates a signal having a phase opposite to that of the drive signal supplied to the predetermined individual electrode as a cancellation signal supplied to the independent electrode corresponding to the predetermined individual electrode. An ink jet printer according to claim 8. When the driving signal is supplied to at least one of the other individual electrodes adjacent to the predetermined individual electrode when the driving signal is supplied to the predetermined individual electrode, Supplying the cancellation signal to the independent electrode corresponding to the predetermined individual electrode;
When a drive signal is supplied to the predetermined individual electrode, if the drive signal is not supplied to all of the other adjacent individual electrodes, the cancellation signal is applied to the independent electrode corresponding to the predetermined individual electrode. The ink jet printer according to claim 8 or 9, wherein the ink jet printer is not supplied. A flow path unit in which a plurality of pressure chambers communicating with the nozzle are arranged adjacent to each other in a matrix along a plane, and an actuator unit fixed to one surface of the flow path unit to change the volume of the pressure chamber. Prepared,
The actuator unit is
A plurality of individual electrodes arranged facing each of the plurality of pressure chambers and supplied with a drive signal for changing the volume of the pressure chamber;
A common electrode provided over a plurality of pressure chambers;
A piezoelectric sheet sandwiched between the individual electrodes and the common electrode, and deformed when a drive signal is supplied to the individual electrodes;
A plurality of independent electrodes provided corresponding to each of the plurality of individual electrodes in a non-opposing region that does not oppose at least the pressure chamber in a region occupied by the piezoelectric sheet;
When the drive signal is supplied to a predetermined individual electrode and the piezoelectric sheet is deformed, a cancellation signal for canceling the distortion of the piezoelectric sheet extending to the position of the other adjacent individual electrode, which is applied to the predetermined individual electrode. Cancellation signal generating means for generating a cancellation signal supplied to the corresponding independent electrode;
An ink jet head comprising:

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