JP5347754B2 - Liquid ejection device - Google Patents

Description

  The present invention relates to a liquid ejection device that ejects liquid from ejection ports.

In an inkjet head that ejects ink droplets from an ejection port, there is a technique for performing non-ejection flushing that vibrates a meniscus formed at the ejection port by driving an actuator to such an extent that no ink droplets are ejected from the ejection port (for example, Patent Document 1). By performing non-ejection flushing, the ink in the ejection port is agitated without ejecting ink droplets, and the viscosity of the ink in the ejection port that has increased in viscosity due to drying or the like can be reduced. Thereby, the ink ejection characteristics are recovered.

Japanese Patent No. 4003038 (FIG. 4)

  In the above-described technique, non-ejection flushing is performed on all the ejection ports at the same time, so that all the actuators corresponding to the ejection ports are driven at the same time, which increases power consumption.

  An object of the present invention is to provide a liquid discharge apparatus that can reduce the viscosity of the liquid in the discharge port and save power.

A liquid discharge apparatus according to a first aspect of the present invention includes a flow path unit having a plurality of individual liquid flow paths that reach a discharge port through each of a plurality of pressure chambers arranged in a matrix, and the plurality of pressure chambers. An actuator unit having a continuous piezoelectric layer, a plurality of individual electrodes disposed on the surface of the piezoelectric layer so as to face each pressure chamber, and a common electrode sandwiching the piezoelectric layer together with the plurality of individual electrodes And a pressure chamber block including a reference pressure chamber that is one of the pressure chambers and all the pressure chambers adjacent to the reference pressure chamber so as to be adjacent to each other and not to overlap each other. An allocation determining unit that determines allocation of the plurality of arranged pressure chamber blocks, and a non-ejection drive signal that deforms the piezoelectric layer within a range in which liquid is not ejected from the ejection port. A discharge signal generating means, for each timing when the allocation determining means determines the allocation of the pressure chamber block, only the individual electrode opposed to the reference pressure chamber according to the pressure chambers blocks, by the non-ejection signal generating means Signal supply control means for supplying the generated non-ejection drive signal, wherein the non-ejection drive signal is simultaneously applied to the individual electrodes facing the reference pressure chambers of the pressure chamber blocks determined at the same timing. And signal supply control means for supplying . In the plan view, the allocation determining means passes through the center of the reference pressure chamber and the center of the pressure chamber adjacent to the reference pressure chamber, and on all straight lines intersecting with each other at the center of the reference pressure chamber, The pressure chamber blocks are allocated so that three pressure chambers are arranged and three pressure chambers are arranged in each of the first direction and the second direction intersecting the first direction. And determining the allocation of the plurality of pressure chamber blocks so that all the pressure chambers in the pressure chamber block whose allocation is determined at one timing become the reference pressure chamber with the same probability , In addition, any one of the plurality of pressure chambers adjacent to the reference pressure chamber in the pressure chamber block whose assignment is determined at the one timing is the reference pressure chamber. As described above, the allocation of the plurality of pressure chamber blocks is determined at a timing subsequent to the one timing .

Further , the liquid ejection device according to the second aspect of the present invention includes a flow path unit having a plurality of individual liquid flow paths that reach a discharge port through each of a plurality of pressure chambers arranged in a matrix, and the plurality of pressure chambers. A continuous piezoelectric layer so as to face each other, a plurality of individual electrodes arranged on the surface of the piezoelectric layer so as to face each pressure chamber, and a common electrode sandwiching the piezoelectric layer together with the plurality of individual electrodes An actuator unit, non-ejection signal generating means for generating a non-ejection drive signal for deforming the piezoelectric layer within a range in which liquid is not ejected from the ejection port, a reference pressure chamber that is one of the pressure chambers, and the reference pressure chamber A plurality of pressure chamber blocks arranged adjacent to each other and not to overlap each other. The non-ejection drive signal generated by the non-ejection signal generation means is supplied only to the individual electrode facing the pressure chamber having the same relative position with respect to the reference pressure chamber in each pressure chamber block. Signal supply control means for simultaneously supplying the non-ejection drive signal to the individual electrodes facing the pressure chambers having the same relative position with respect to the reference pressure chambers of the respective pressure chamber blocks. Supply control means . Each pressure chamber block, in plan view, passes through the center of the reference pressure chamber and the center of the pressure chamber adjacent to the reference pressure chamber, and on all straight lines intersecting with each other at the center of the reference pressure chamber, Three pressure chambers are arranged, and three pressure chambers are arranged in each of the first direction and the second direction crossing the first direction. The signal supply control means sequentially supplies the non-ejection drive signal to the individual electrodes facing each pressure chamber included in the pressure chamber block.

  According to the present invention, the non-ejection drive signal is not supplied to the individual electrodes opposed to all the pressure chambers adjacent to the specific pressure chamber while the non-ejection drive signal is supplied to the individual electrode opposed to the specific pressure chamber. As a result, the region facing the specific pressure chamber related to the piezoelectric layer is deformed, and the deformation propagates to deform the region facing all the pressure chambers adjacent to the specific pressure chamber related to the piezoelectric layer. . Thereby, the meniscus formed in the discharge port regarding not only the specific pressure chamber but also other pressure chambers adjacent to the pressure chamber vibrates, and the viscosity of the liquid in the discharge port can be efficiently reduced. Thereby, the number of times of supplying the non-ejection drive signal to the individual electrodes can be reduced and the power consumption can be suppressed.

Moreover, in the liquid ejecting apparatus according to the first aspect of the present invention , the allocation determining means includes a plurality of pressure chambers adjacent to the reference pressure chamber in the pressure chamber block whose allocation is determined at the one timing. The allocation of the plurality of pressure chamber blocks is determined at a timing subsequent to the one timing so that any one becomes the reference pressure chamber, and the signal supply control means is configured so that the allocation determination means The non-ejection drive signal is supplied only to the individual electrodes facing each reference pressure chamber at every timing for determining allocation . According to this, the vibration amount of the meniscus can be made uniform for all the discharge ports.

  At this time, the allocation determining means may determine the allocation of the pressure chamber block at a predetermined cycle. According to this, the allocation determining means can be configured easily.

Moreover, Te liquid ejection apparatus odor according to the first aspect of the present invention, the allocation determining means, in a plan view, while passing through a center of the pressure chamber adjacent to the center and the reference pressure chamber of the reference pressure chamber, The allocation of the pressure chamber blocks is determined so that three of the pressure chambers are arranged on all straight lines intersecting each other at the center of the reference pressure chamber . Further, in the liquid ejection apparatus according to the second aspect of the present invention, each pressure chamber block passes through the center of the reference pressure chamber and the center of the pressure chamber adjacent to the reference pressure chamber in plan view. Three pressure chambers are arranged on all straight lines intersecting each other at the center of the reference pressure chamber. According to this, the pressure chamber block can be easily determined.

Further, in the liquid discharge apparatus according to a first aspect of the present invention, the allocation determining means, so that the pressure chamber for each of the second direction are three sequences which intersects the first direction and the first direction, determining the allocation of the pressure chamber block. Further, in the liquid ejection device according to the second aspect of the present invention, each pressure chamber block has three pressure chambers arranged in each of the first direction and the second direction intersecting the first direction. It is configured. According to this, the pressure chamber block can be determined more easily.

  In the present invention, the image forming apparatus further includes discharge drive signal generation means for generating a discharge drive signal for discharging liquid from the discharge port based on image data, and the signal supply control means includes the discharge drive signal and the non-discharge. When the drive signal is to be supplied to the same individual electrode at the same timing, it is preferable that only the ejection drive signal is supplied to the individual electrode. According to this, non-ejection flushing can be performed on the ejection ports that are not ejecting other liquids while ejecting liquid from the ejection ports.

  According to the present invention, the non-ejection drive signal is not supplied to the individual electrodes opposed to all the pressure chambers adjacent to the specific pressure chamber while the non-ejection drive signal is supplied to the individual electrode opposed to the specific pressure chamber. As a result, the region facing the specific pressure chamber related to the piezoelectric layer is deformed, and the deformation propagates to deform the region facing all the pressure chambers adjacent to the specific pressure chamber related to the piezoelectric layer. . Thereby, the meniscus formed in the discharge port regarding not only the specific pressure chamber but also other pressure chambers adjacent to the pressure chamber vibrates, and the viscosity of the liquid in the discharge port can be efficiently reduced. Thereby, the number of times of supplying the non-ejection drive signal to the individual electrodes can be reduced and the power consumption can be suppressed.

1 is a cross-sectional view of an inkjet printer according to an embodiment of the present invention. It is sectional drawing along the width direction of the inkjet head shown in FIG. It is sectional drawing regarding the III-III line | wire shown in FIG. It is an enlarged view of the area | region enclosed with the dashed-dotted line shown in FIG. (A) It is a fragmentary sectional view of the actuator unit shown in FIG. (B) It is a partial top view of an actuator unit. It is a functional block diagram of the control apparatus shown in FIG. (A) It is a wave form diagram of the discharge drive signal which the discharge signal generation part shown in Drawing 6 generates. (B) It is a wave form diagram of the non-ejection drive signal which the non-ejection signal generation part shown in Drawing 6 generates. It is the figure which showed the pressure chamber block by which allocation was determined by the allocation determination part shown in FIG. It is an enlarged view of the pressure chamber block shown in FIG. It is a figure which shows the reference example which concerns on a pressure chamber.

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

  As shown in FIG. 1, the ink jet printer 101 has a rectangular parallelepiped housing 1a. A paper discharge unit 31 is provided on the top of the housing 1a. Furthermore, the inside of the housing 1a is divided into three spaces A, B, and C in order from the top. In the space A, four inkjet heads 1 and a transport unit 20 that respectively eject magenta, cyan, yellow, and black inks are arranged. Spaces B and C are spaces in which a paper feed unit 1b and an ink tank unit 1c that can be attached to and detached from the housing 1a are arranged. In the present embodiment, the sub-scanning direction is a direction parallel to the transport direction when the paper P is transported by the transport unit 20, and the main scanning direction is a direction orthogonal to the sub-scanning direction and along the horizontal plane. Direction.

  Inside the ink jet printer 101, a paper transport path for transporting the paper P from the paper feed unit 1b toward the paper discharge unit 31 is formed (thick arrow in FIG. 1). The sheet feeding unit 1 b includes a sheet feeding tray 23 that can store a plurality of sheets P, and a sheet feeding roller 25 attached to the sheet feeding tray 23. The paper feed roller 25 sends out the uppermost paper P among the plurality of papers P stacked and stored in the paper feed tray 23. The paper P sent out by the paper feed roller 25 is guided to the guides 27 a and 27 b and sent to the transport unit 20 while being sandwiched by the feed roller pair 26.

  The transport unit 20 includes two belt rollers 6, 7, an endless transport belt 8 wound around the rollers 6, 7, and a tension roller 10. The tension roller 10 applies tension to the conveyor belt 8 by being urged downward in the lower loop of the conveyor belt 8 while being in contact with the inner peripheral surface thereof. The belt roller 7 is a driving roller, and rotates clockwise in FIG. 1 when a driving force is applied from the transport motor M through two gears. The belt roller 6 is a driven roller, and rotates clockwise in FIG. 1 as the conveyor belt 8 travels as the belt roller 7 rotates.

  The outer peripheral surface 8a of the conveyor belt 8 is subjected to silicone treatment and has adhesiveness. A nip roller 4 is disposed at a position facing the belt roller 6 with the conveyance belt 8 interposed therebetween on the paper conveyance path. The nip roller 4 presses the sheet P sent out from the sheet feeding unit 1 b against the outer peripheral surface 8 a of the transport belt 8. The paper P pressed against the outer peripheral surface 8a is conveyed rightward in FIG. 1 while being held on the outer peripheral surface 8a by the adhesive force.

  Further, a peeling plate 5 is provided at a position facing the belt roller 7 with the conveyance belt 8 interposed therebetween on the paper conveyance path. The peeling plate 5 peels the paper P from the outer peripheral surface 8a. The peeled paper P is guided by the guides 29a and 29b and conveyed while being sandwiched between the two pairs of feed rollers 28, and is discharged from the opening 30 at the top of the housing 1a to the paper discharge unit 31.

  The four inkjet heads 1 are supported by the housing 1a via the frame 3. The four inkjet heads 1 each extend along the main scanning direction and are arranged in parallel to each other in the sub-scanning direction. That is, the ink jet printer 101 is a line type color ink jet printer in which an ejection region extending in the main scanning direction is formed. The lower surface of each inkjet head 1 is an ejection surface 2a from which ink droplets are ejected.

A platen 19 is disposed in the loop of the conveyor belt 8 so as to face the four inkjet heads 1. The upper surface of the platen 19 is in contact with the inner peripheral surface of the upper loop of the conveyor belt 8 and supports it from the inner peripheral side of the conveyor belt 8. Thereby, the outer peripheral surface 8a of the upper loop of the conveyor belt 8 and the lower surface of the inkjet head 1, that is, the ejection surface 2a are parallel to each other, and a gap with a predetermined interval suitable for image formation is formed. The gap constitutes a part of the paper transport path. When the paper P transported by the transport belt 8 passes just below the four heads 1, ink of each color is sequentially ejected from each head 1 toward the upper surface of the paper P, and a desired color is applied onto the paper P. An image is formed.

  Each inkjet head 1 is connected to an ink tank 49 mounted on the ink tank unit 1c in the space C. That is, the ink discharged from the corresponding inkjet head 1 is stored in each of the four ink tanks 49. Then, ink is supplied from each ink tank 49 to the inkjet head 1 via a tube (not shown) or the like.

  Next, the inkjet head 1 will be described in detail with reference to FIGS. In FIG. 3, the lower housing 87 is omitted.

  As shown in FIG. 2, the inkjet head 1 includes a reservoir unit 71, a head body 2 including a flow path unit 9 and an actuator unit 21, a COF in which one end is connected to the actuator unit 21 and a driver IC 52 is mounted. (Chip On Film: flat flexible substrate) 50 and a control substrate 54 to which the other end of the COF 50 is connected. Further, the inkjet head 1 includes an upper housing 86 and a lower housing 87 that form a box surrounding the reservoir unit 71 and the flow path unit 9, and a head cover 55 that surrounds the control substrate 54 above the upper housing 86. have.

  The reservoir unit 71 is a flow path forming member that is fixed to the upper surface of the head body 2 and supplies ink to the head body 2. The reservoir unit 71 is a stacked body in which four plates 91 to 94 are aligned and stacked, and an ink inflow channel (not shown), an ink reservoir 72, and 10 The ink outflow channels 73 are formed so as to communicate with each other. In FIG. 2, only one ink outflow channel 73 appears. The ink inflow channel is a channel into which ink from the ink tank 49 flows. The ink reservoir 72 is an ink reservoir that temporarily stores the ink that has flowed from the ink inflow passage. The ink outflow channel 73 is a channel through which the ink from the ink reservoir 72 flows out, and communicates with the ink supply port 105 b formed on the upper surface of the channel unit 9. The ink from the ink tank 49 flows into the ink reservoir 72 through the ink inflow channel, passes through the ink outflow channel 73, and is supplied to the channel unit 9 from the ink supply port 105b.

  Further, a recess 94 a is formed on the lower surface of the plate 94. The recess 94 forms a gap 90 between the upper surface of the flow path unit 9. In the gap 90, the four actuator units 21 on the flow path unit 9 are arranged at equal intervals along the longitudinal direction of the flow path unit 9. Further, four openings 90a of the gap 90 are formed in a staggered manner at equal intervals along the longitudinal direction of the reservoir unit 71 on the side surface of the laminate.

  Further, the lower surface of the plate 94 has a convex portion (a portion other than the concave portion 94 a) bonded to the flow path unit 9. An ink outflow channel 73 is formed in the convex portion.

  The vicinity of one end of the COF 50 is connected to the upper surface of the actuator unit 21. Further, the COF 50 extends from the upper surface of the actuator unit 21 in the horizontal direction and passes through the opening 90 a, and then is pulled out along the side wall of the reservoir unit 71 through a gap with the upper housing 86 or the lower housing 87. It is. A cutout 53 is formed in the inner wall surface of the upper casing 86 and the lower casing 87, and a drawer path through which the COF 50 is pulled out is configured. The COF 50 is drawn above the upper housing 86 from the slit 86 a formed in the upper housing 86 above the reservoir unit 71. The other end of the COF 50 is connected to the control board 54 via the connector 54a above the upper housing 86. The driver IC 52 mounted on the COF 50 is affixed to the upper surface of the reservoir unit 71 and is thermally coupled to the reservoir unit 71. Thereby, the heat generated from the driver IC 52 is transmitted to the reservoir unit 71 to cool the driver IC 52, while the ink viscosity in the reservoir unit 71 is suppressed from being increased by warming the ink in the reservoir unit 71.

  The control board 54 is disposed above the upper housing 86 and controls the driving of the actuator unit 21 via the driver IC 52 of the COF 50. The driver IC 52 generates a drive signal that drives the actuator unit 21.

  Further, the head body 2 will be described with reference to FIGS. 3 and 4. In FIG. 4, for convenience of explanation, the pressure chamber 110, the aperture 112, and the discharge port 108 that are to be drawn by broken lines below the actuator unit 21 are drawn by solid lines.

  As shown in FIG. 3, the head body 2 is a laminated body in which four actuator units 21 are fixed to the upper surface 9 a of the flow path unit 9. As shown in FIGS. 3 and 4, the flow path unit 9 has an ink flow path including a pressure chamber 110 and the like formed therein. The actuator unit 21 includes a plurality of actuators corresponding to the pressure chambers 110, and has a function of selectively giving ejection energy to the ink in the pressure chambers 110.

  A total of ten ink supply ports 105 b are opened on the upper surface 9 a of the flow path unit 9 corresponding to the ink outflow flow path 73 (see FIG. 2) of the reservoir unit 71. As shown in FIG. 3, the flow path unit 9 has a manifold flow path 105 communicating with the ink supply port 105b, a sub-manifold flow path 105a branched from the manifold flow path 105, and further branched from the sub-manifold flow path 105a. A large number of individual ink flow paths 132 are formed. As shown in FIG. 4, a discharge surface 2a is formed on the lower surface of the flow path unit 9, and a large number of discharge ports 108 are arranged in a matrix. A large number of pressure chambers 110 having a rhombic planar shape with rounded corners are also arranged in a matrix in the first direction and the second direction intersecting the same on the upper surface 9a of the flow path unit 9 (fixing surface of the actuator unit 21). (See FIG. 8). The ejection ports 108 are arranged at an interval of 600 dpi, which is the resolution in the main scanning direction with respect to the main scanning direction.

  In the present embodiment, 16 rows of pressure chambers 110 arranged at equal intervals in the longitudinal direction of the flow path unit 9 are arranged in parallel to each other in the width direction. The number of pressure chambers 110 included in each pressure chamber row corresponds to the outer shape (trapezoidal shape) of an actuator unit 21 described later, from the long side (lower base side) to the short side (upper base side). It arrange | positions so that it may decrease gradually toward it. The discharge port 108 is also arranged corresponding to this.

  The flow path unit 9 is a laminated body in which a plurality of metal plates made of stainless steel are aligned with each other. A large number of individual ink flow paths 132 are formed in the flow path unit 9 from the manifold flow path 105 to the sub-manifold flow path 105a and from the outlet of the sub-manifold flow path 105a to the discharge port 108 through the pressure chamber 110.

  The ink flow in the flow path unit 9 will be described. As shown in FIGS. 3 to 4, the ink supplied from the reservoir unit 71 into the flow path unit 9 through the ink supply port 105 b is distributed from the manifold flow path 105 to the sub-manifold flow path 105 a. The ink in the sub-manifold channel 105 a flows into each individual ink channel and reaches the ejection port 108 via the pressure chamber 110.

  Next, the actuator unit 21 will be described. As shown in FIG. 5A, the actuator unit 21 includes three piezoelectric sheets 141 to 143 made of a lead zirconate titanate (PZT) ceramic material having ferroelectricity. An individual electrode 135 is formed at a position facing the pressure chamber 110 on the upper surface of the uppermost piezoelectric sheet 141. A common electrode 134 formed on the entire surface of the sheet is interposed between the uppermost piezoelectric sheet 141 and the lower piezoelectric sheet 142. As shown in FIG. 5B, the individual electrode 135 has a substantially rhombic planar shape similar to the pressure chamber 110. In plan view, most of the individual electrodes 135 are in the region of the pressure chamber 110. One of the acute angle portions of the substantially rhomboid individual electrode 135 extends outside the pressure chamber 110, and an individual bump 136 electrically connected to the individual electrode 135 is provided at the tip thereof.

  The common electrode 134 is equally grounded in the region corresponding to all the pressure chambers 110. On the other hand, the individual electrode 135 is electrically connected to each output terminal of the driver IC 52 via the COF 50, and a drive signal from the driver IC 52 is selectively supplied.

  In the actuator unit 21, a portion sandwiched between the individual electrode 135 and the pressure chamber 110 functions as an individual actuator. The piezoelectric sheet 141 away from the pressure chamber 110 is a layer including an active portion, and the two piezoelectric sheets 142 and 143 near the pressure chamber 110 are inactive layers that are not spontaneously deformed. The actuator unit 21 is a so-called unimoful type actuator. In the actuator unit 21, individual actuators are built in at least as many as the pressure chambers 110.

  Here, a driving method of the actuator unit 21 will be described. The piezoelectric sheet 141 is polarized in the thickness direction. When an electric field is applied to the piezoelectric sheet 141 in a polarization direction by setting the individual electrode 135 to a potential different from that of the common electrode 134, the electric field application portion of the piezoelectric sheet 141 functions as an active portion and is distorted by the piezoelectric effect. For example, if the polarization direction is the same as the electric field application direction, the active portion contracts in a direction (plane direction) perpendicular to the polarization direction. At this time, the piezoelectric sheets 142 and 143 are not spontaneously strained by an electric field. There is a difference in distortion in the plane direction between the electric field application portion of the piezoelectric sheet 141 and the piezoelectric sheets 142 and 143. Furthermore, as shown in FIG. 5A, the piezoelectric sheets 141 to 143 are fixed to the upper surface of the plate 122 that partitions the pressure chamber 110, so that the entire piezoelectric sheets 141 to 143 are convex toward the pressure chamber 110. (Unimorph deformation). As a result, pressure (discharge energy) is applied to the ink in the pressure chamber 110, and ink droplets are discharged from the discharge ports 108.

  In the present embodiment, a predetermined potential V1 is applied to the individual electrode 135 in advance, and the individual electrode 135 is once set to the ground potential V0 every time there is a discharge request, and then again to the individual electrode 135 at a predetermined timing. A drive signal for applying the potential V1 is output from the driver IC 52 (see FIG. 7). In this case, the piezoelectric sheets 141 to 143 return to the original state at the timing when the individual electrode 135 becomes the ground potential V0, and the volume of the pressure chamber 110 increases compared to the initial state (a state in which a voltage is applied in advance), Ink is sucked from the sub-manifold channel 105 a into the individual ink channel 132. After that, at the timing when the predetermined potential V1 is applied to the individual electrode 135 again (the timing at which the sucked ink reaches the pressure chamber 110), the portions facing the active region in the piezoelectric sheets 141 to 143 are convex toward the pressure chamber 110 side. Thus, the pressure of the ink increases due to a decrease in the volume of the pressure chamber 110, and ink is ejected from the ejection port 108.

  Next, the control device 16 will be described with reference to FIG. The control device 16 includes a CPU (Central Processing Unit), a program executed by the CPU, and an EEPROM (Electrically Erasable and Programmable Read Only Memory) that stores data used for these programs in a rewritable manner. It includes RAM (Random Access Memory) for temporary storage. Each functional unit constituting the control device 16 is constructed by cooperation of these hardware and software in the EEPROM. As shown in FIG. 6, the control device 16 controls the entire inkjet printer 101 in cooperation with the control board 54 and the driver IC 52, and includes a conveyance control unit 41, an image data storage unit 42, and an ejection signal generation. A unit 43, an allocation determination unit 44, a non-ejection signal generation unit 45, and a signal supply control unit 46.

  The transport control unit 41 controls the transport motor M of the transport unit 20 so that the paper P is transported along the transport direction. At the time of image formation, the paper P is fed out from the paper feed tray 23 in accordance with the drive start timing of the actuator unit 21.

  The image data storage unit 42 stores image data relating to an image to be printed on the paper P. The image data is obtained by assigning the volume of ink droplets for forming each image dot constituting the image to each ejection port 108 of each inkjet head 1 for each printing cycle. In the present embodiment, the ink droplets ejected from the ejection port 108 are assigned any one selected from four types of volumes (large droplets, medium droplets, small droplets, 0). The print cycle is the time required for the paper P to be transported by a unit distance corresponding to the print resolution in the transport direction.

  The ejection signal generation unit 43 generates an ejection drive signal that is a drive signal for deforming the actuator unit 21 such that an ink droplet is ejected from the ejection port 108. As shown in FIG. 7A, the ejection drive signal is a signal including a pulse that changes from the potential V1 to the ground potential V0 for a predetermined time in one printing cycle. This pulse width is equal to the time t during which the pressure wave propagates a distance AL (Acoustic Length) length from the outlet of the sub-manifold channel 105a to the discharge port 108. The waveform in FIG. 7A is a waveform when ink is ejected as a small droplet, and has one pulse within one printing cycle. The waveform when ejected as a medium droplet has two pulses, and the waveform when ejected as a large droplet has three pulses. In this case, each waveform may include a cancel pulse for suppressing residual vibration of each ejection pulse from the viewpoint of ejection stability.

  The allocation determining unit 44 allocates the plurality of pressure chamber blocks 80 when performing non-ejection flushing that reduces the viscosity of the ink in the ejection port 108 by vibrating the ink meniscus formed in the ejection port 108. decide. The pressure chamber block 80 is a unit area to which a non-ejection drive signal for non-ejection flushing is supplied, and a plurality of pressure chambers 110 are included in the same arrangement form in each area. The non-ejection flushing is performed from the start of printing on one or a plurality of sheets P until the printing is completed.

  In the pressure chamber block 80, a plurality of pressure chambers 110 are arranged in each of the first direction and the second direction crossing the first direction in the drawing. For example, as shown in FIG. 8, the pressure chamber block 80 includes a total of nine reference pressure chambers 110a, which are one pressure chamber 110, and eight adjacent pressure chambers 110b adjacent to both sides across the reference pressure chamber 110a. The pressure chamber 110 is configured. Further, in the pressure chamber block 80, in plan view, on all straight lines (four straight lines: crossing each other at the center of the reference pressure chamber 110a while passing through the center of the reference pressure chamber 110a and the center of the adjacent pressure chamber 110b). Three pressure chambers 110 are arranged on each of the broken lines in the figure. In this case, the pressure chamber block 80 has a substantially rhombus outer shape similar to the pressure chamber 110. The allocation determining unit 44 determines the allocation of the plurality of pressure chamber blocks 80 so as to be adjacent to each other and not overlap each other. In this way, the allocation determining unit 44 extracts the reference pressure chambers 110a that are not adjacent to each other.

  The assignment determination unit 44 assigns each pressure chamber 110 to one pressure chamber block 80 so that nine pressure chambers 110 are included at one timing. The allocation determining unit 44 repeats this allocation operation at a predetermined cycle to set all the pressure chambers 110 in the pressure chamber block 80 as the reference pressure chambers 110a with the same probability.

  Specifically, the assignment determining unit 44 first determines each pressure chamber block 80 at one timing, and for example, the pressure chamber 110 at the position indicated by number 1 in FIG. 9 is replaced with the first reference pressure chamber 110a. Extract as At the next timing subsequent to one timing, the allocation determining unit 44 sets a new reference pressure chamber 110a as an adjacent pressure chamber 110b adjacent to the first reference pressure chamber 110a (at the position indicated by number 2 in FIG. 9). The adjacent pressure chamber 110b) is extracted. The allocation determining unit 44 continues this allocation operation in order for the other adjacent pressure chambers 110b arranged around the first reference pressure chamber 110a. In the present embodiment, in one pressure chamber block 80, following the determination of the first reference pressure chamber 110a, eight allocation operations are continuously performed in the clockwise order (number 2 to number 9 in the figure). Done. In this way, by continuously determining the allocation of the pressure chamber block 80 nine times, all the pressure chambers 110 related to the pressure chamber block 80 determined by the allocation at a certain timing are sequentially connected to the reference pressure chamber 110a. Become.

  The non-ejection signal generation unit 45 generates a non-ejection driving signal that is a driving signal for driving the actuator unit 21 within a range where ink droplets are not ejected from the ejection port 108. As shown in FIG. 7B, the non-ejection drive signal is a signal in which a pulse from the potential V1 to the ground potential V0 for a predetermined time is repeated at a predetermined cycle (8 μm in this embodiment). This pulse width is preferably 1/3 or less of the time t during which the pressure wave propagates through the AL length.

  The signal supply control unit 46 simultaneously supplies the non-ejection drive signal generated by the non-ejection signal generation unit 45 for each period in which the allocation determination unit 44 determines the allocation of the pressure chamber block 80. At this time, a predetermined number of non-ejection drive signals are supplied only to the individual electrodes 135 facing each reference pressure chamber 110a.

  Here, when the actuator corresponding to the reference pressure chamber 110 a is driven, the vibration is transmitted to the adjacent pressure chamber 110. If the adjacent pressure chamber 110b is also driven in the same manner, its own vibration is hindered by the propagating vibration, and the stirring effect of the ink near the ejection port becomes low. However, since only the reference pressure chamber 110a is driven, and the adjacent pressure chamber 110b vibrates in response to the signal, the drive to the adjacent pressure chamber 110b correspondingly (the total number of pulses of the non-ejection drive signal to be applied). Can be limited.

  From another viewpoint, the signal supply control unit 46 sets the pressure chamber 110 in the fixed pressure chamber block 80 to have the same relative position with respect to the reference pressure chamber 110a related to each pressure chamber block 80. A non-ejection drive signal is supplied only to the opposing individual electrode 135, and a non-ejection drive signal is sequentially supplied to the individual electrode 135 facing each pressure chamber 110 in the pressure chamber block 80 in a predetermined cycle.

  Further, the signal supply control unit 46 applies the ejection drive signal generated by the ejection signal generation unit 43 to the individual electrode 135 facing the pressure chamber 110 that performs the ink droplet ejection operation based on the image data at a desired timing. Supply. When supplying the ejection drive signal and the non-ejection drive signal to the same individual electrode 135 at the same timing, the signal supply control unit 46 supplies only the ejection drive signal to the individual electrode 135. Thus, even when printing is performed on the paper P, non-ejection flushing can be performed on the ejection port 108 that does not eject ink droplets.

  As described above, according to the inkjet printer 101 of the present embodiment, in order to perform non-ejection flushing, the non-ejection driving signal is supplied to the individual electrode 135 facing the reference pressure chamber 110a, whereby the piezoelectric sheet 141 and the reference pressure are supplied. As the chamber 110a deforms (vibrates), the deformation propagates, and the portions (including the piezoelectric sheet 141 and the adjacent pressure chamber 110b) related to all the adjacent pressure chambers 110b adjacent to the reference pressure chamber 110a are also deformed. As a result, the meniscus formed at the ejection ports 108 for all the pressure chambers 110 in each pressure chamber block 80 vibrates and non-ejection flushing is performed, thereby effectively reducing the viscosity of the ink in the ejection ports 108. it can. For this reason, the number of times of supplying the non-ejection drive signal to the individual electrode 135 can be reduced and the power consumption can be suppressed.

  Moreover, since the allocation determination part 44 determines allocation of the pressure chamber block 80 with a predetermined period, the allocation determination part 44 can be comprised easily.

  In plan view, the allocation determining unit 44 passes through the center of the reference pressure chamber 110a and the center of the adjacent pressure chamber 110b, and on all straight lines (broken lines in the figure) intersecting each other at the center of the reference pressure chamber 110a. Since the allocation of the pressure chamber block 80 is determined so that three chambers 110 are arranged, the pressure chamber block 80 can be easily determined.

  At this time, the allocation determining unit 44 determines the allocation of the pressure chamber block 80 in which the three pressure chambers are arranged in each of the first direction and the second direction, so that the pressure chamber block 80 is more easily determined. Can do. Further, as shown in FIGS. 8 and 9, the first direction and the second direction are directions in which the substantially rhombic reference pressure chamber 110a and the adjacent pressure chamber 110b are opposed to each other in parallel with each other. It is easy to reliably transmit the vibration of the reference pressure chamber 110a to the adjacent pressure chamber 110b.

  Further, when the signal supply control unit 46 tries to supply the ejection drive signal and the non-ejection drive signal to the same individual electrode 135 at the same timing, only the ejection drive signal is supplied to the individual electrode 135. It is possible to perform non-ejection flushing on the other ejection ports 108 that are not ejecting ink droplets while ejecting ink droplets from the ejection ports 108 that perform the above.

< Reference example>
Reference examples according to the present invention will be described. The pressure chamber 110 according to the embodiment described above is configured to have a planar shape of a rhombus, the pressure chamber 210 according to this reference example, Ru configuration der having other planar shapes. As shown in FIG. 10, the pressure chamber 210 according to the present embodiment will have a planar shape of a hexagon (regular hexagon and modified hexagons). At this time, the allocation determining unit may determine the allocation of the pressure chamber block 280 configured by the reference pressure chamber 210a and the six adjacent pressure chambers 210b adjacent to the reference pressure chamber 210a. In the pressure chamber block 280, on a straight line passing through the center of the reference pressure chamber 210a and the center of the adjacent pressure chamber 210b while crossing each other at the center of the reference pressure chamber 210a (three straight lines in the figure). Three pressure chambers 210 are arranged in a broken line).

  The preferred embodiments of the present invention have been described above. However, the present invention is not limited to the above-described embodiments, and various modifications can be made as long as they are described in the claims. In the above-described embodiment, the allocation determination unit 44 is configured to determine the allocation of the pressure chamber block 80 at a predetermined cycle. However, even if the allocation determination unit determines the allocation of the pressure chamber block 80 at an arbitrary timing. Good. For example, the allocation determining unit may determine the allocation of the pressure chamber block 80 in two or more cycles.

  Further, in the above-described embodiment, when the ink droplets are ejected from the ejection port 108, the non-ejection flushing can be performed on the other ejection ports 108. However, the signal supply control unit When ejecting ink droplets from the ejection port 108, the other ejection port 108 may be configured not to perform non-ejection flushing. In this case, when ink droplets are not ejected onto the paper P, for example, non-ejection flushing may be performed only immediately before printing is performed on the paper P.

  Furthermore, in the above-described embodiment, the allocation determining unit sets the pressure chamber blocks 80 and 280 as regions that include the adjacent pressure chambers 110b and 210b adjacent to the reference pressure chambers 110a and 210a via lines or points. Although it has been allocated, it may be allocated so as to include a plurality of pressure chambers 110 and 210 arranged so as to surround the outside.

  Further, in the above-described embodiment, the pressure chamber block allocation operation by the allocation determination unit is performed at each timing when the non-ejection flushing is necessary. For example, when the power is turned on, the allocation determination unit previously performs the allocation operation. Is completed and stored, and at the timing (cycle) at which non-ejection flushing becomes necessary, non-ejection flushing for the reference pressure chamber may be performed according to the stored allocation pattern.

  Furthermore, the allocation of the pressure chamber blocks by the allocation determining unit is determined such that the pressure chambers to be extracted as the reference pressure chambers at random are random, but the plurality of pressure chamber blocks are adjacent to each other and do not overlap. Also good. As a result, the arrangement form of the first pressure chamber block changes every time a series of assignment operations are performed by the assignment determining unit, and the ink stirring effect in the vicinity of the ejection port is not biased based on the arrangement form.

  The present invention is also applicable to a recording apparatus that ejects liquid other than ink. Further, the present invention is not limited to a printer, and can be applied to a facsimile, a copier, and the like.

DESCRIPTION OF SYMBOLS 1 Inkjet head 2 Head main body 2a Discharge surface 9 Flow path unit 16 Control apparatus 21 Actuator unit 41 Conveyance control part 42 Image data storage part 43 Discharge signal generation part 44 Assignment determination part 45 Non-discharge signal generation part 46 Signal supply control part 80, 280 Pressure chamber block 101 Inkjet printer 108 Discharge port 110, 210 Pressure chamber 110a, 210a Reference pressure chamber 110b, 210b Adjacent pressure chamber 134 Common electrode 135 Individual electrodes 141-143 Piezoelectric sheet

Claims (4)

A flow path unit having a plurality of individual liquid flow paths that reach the discharge port through each of a plurality of pressure chambers arranged in a matrix;
A piezoelectric layer continuous so as to face the plurality of pressure chambers, a plurality of individual electrodes disposed on the surface of the piezoelectric layer so as to face each pressure chamber, and the piezoelectric layer sandwiched together with the plurality of individual electrodes An actuator unit having a common electrode
A pressure chamber block including one reference pressure chamber, which is one of the pressure chambers, and all the pressure chambers adjacent to the reference pressure chamber, arranged adjacent to each other and not overlapping each other. Allocation determining means for determining allocation of the plurality of pressure chamber blocks;
Non-ejection signal generating means for generating a non-ejection driving signal for deforming the piezoelectric layer within a range in which liquid is not ejected from the ejection port;
The non-ejection signal generated by the non-ejection signal generation unit is applied only to the individual electrode facing the reference pressure chamber associated with each pressure chamber block at every timing when the allocation determination unit determines the allocation of the pressure chamber block. Signal supply control means for supplying a drive signal, wherein the signal supply control supplies the non-ejection drive signal simultaneously to the individual electrodes facing the reference pressure chambers related to the pressure chamber blocks determined at the same timing. Means and
The allocation determining means is
In plan view, three pressure chambers pass through the center of the reference pressure chamber and the center of the pressure chamber adjacent to the reference pressure chamber, and on all straight lines that intersect with each other at the center of the reference pressure chamber. Determining the allocation of the pressure chamber blocks so that the three pressure chambers are arranged for each of the first direction and the second direction intersecting the first direction,
The allocation of the plurality of pressure chamber blocks is determined so that all the pressure chambers in the pressure chamber block whose allocation is determined at one timing become the reference pressure chamber with the same probability , and the 1 The plurality of the pressure chambers at a timing subsequent to the one timing so that any one of the plurality of pressure chambers adjacent to the reference pressure chamber in the pressure chamber block whose allocation is determined at one timing becomes the reference pressure chamber. A liquid ejecting apparatus for determining allocation of pressure chamber blocks . The liquid ejection apparatus according to claim 1 , wherein the allocation determining unit determines the allocation of the pressure chamber block at a predetermined cycle. A flow path unit having a plurality of individual liquid flow paths that reach the discharge port through each of a plurality of pressure chambers arranged in a matrix;
A piezoelectric layer continuous so as to face the plurality of pressure chambers, a plurality of individual electrodes disposed on the surface of the piezoelectric layer so as to face each pressure chamber, and the piezoelectric layer sandwiched together with the plurality of individual electrodes An actuator unit having a common electrode
Non-ejection signal generating means for generating a non-ejection driving signal for deforming the piezoelectric layer within a range in which liquid is not ejected from the ejection port;
A pressure chamber block including one reference pressure chamber, which is one of the pressure chambers, and all the pressure chambers adjacent to the reference pressure chamber, arranged adjacent to each other and not overlapping each other. In the plurality of pressure chamber blocks, the non-ejection signal generation unit generates only the individual electrodes facing the pressure chambers that have the same relative position with respect to the reference pressure chamber in each pressure chamber block. The non-ejection drive signal supplying means for supplying the non-ejection drive signal simultaneously with respect to the individual electrodes facing the pressure chambers having the same relative position with respect to the reference pressure chamber in each pressure chamber block. Signal supply control means for supplying the non-ejection drive signal ,
Each pressure chamber block, in plan view, passes through the center of the reference pressure chamber and the center of the pressure chamber adjacent to the reference pressure chamber, and on all straight lines intersecting with each other at the center of the reference pressure chamber, Three pressure chambers are arranged, and three pressure chambers are arranged in each of the first direction and the second direction crossing the first direction, and
The liquid supply apparatus according to claim 1, wherein the signal supply control means supplies the non-ejection drive signal in order to the individual electrodes facing each pressure chamber included in the pressure chamber block. A discharge drive signal generating means for generating a discharge drive signal for discharging liquid from the discharge port based on image data;
The signal supply control means supplies only the ejection drive signal to the individual electrode when trying to supply the ejection drive signal and the non-ejection drive signal to the same individual electrode at the same timing. apparatus according to any one of claim 1 3.

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