JP2013184459A - Liquid jetting device and control method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To control formation of a recess at an intersection of a first line and a second line.SOLUTION: In a unit period T1, a first drive pulse P1 that takes a lead, and a second drive pulse P2 with faster discharge speed than the first drive pulse P1 are generated, and also a third drive pulse P3 that makes an ink droplet I2 accompanied with a satellite droplet I13 is generated in another unit period T2. In addition, when an end edge of a first line that is formed on a recording medium by liquid droplets I1 continuously discharged regarding to a relative moving direction of the recording medium forms an intersection with a second line that intersect with the first line and is formed on the recording medium by the ink droplets l1 discharged from a plurality of nozzle openings in relation to a nozzle row direction, the position of the intersection is detected. The ink droplets l1 to be landed on points other than the intersection are controlled to be discharged by the first drive pulse P1 and the second drive pulse P2, and the ink droplet l2 to be landed in the intersection is controlled to be discharged by the third drive pulse P3.

Description

  The present invention relates to a liquid ejecting apparatus and a control method thereof, and is particularly useful when applied to information having an intersection such that the end of a first line is stopped at a second line at high speed. .

  The liquid ejecting apparatus is an apparatus that includes a liquid ejecting head having a nozzle opening for ejecting liquid and ejects various liquids from the liquid ejecting head. As a typical example of this liquid ejecting apparatus, for example, an ink jet recording head (hereinafter also simply referred to as a recording head) as a liquid ejecting head is provided, and ink droplets are ejected from nozzle openings of the recording head (such as recording paper). An ink jet recording apparatus (hereinafter also referred to as a recording apparatus) that records an image or the like by forming dots by ejecting and landing on a target).

  This type of recording apparatus has a nozzle array in which a plurality of nozzle openings are arranged, and a drive pulse is applied to pressure generating means (for example, a piezoelectric element or a heating element) to drive it. There is a configuration in which a pressure change is generated in the ink in the pressure generation chamber, and the ink is ejected from a nozzle opening communicating with the pressure generation chamber by using the pressure change. More specifically, a drive signal including one or a plurality of drive pulses within a unit cycle that is a repetition unit of the drive signal (for example, a cycle divided by a timing signal such as a LAT signal) is generated, and the pressure generation unit Dots are formed by ejecting the same number of inks as the number of applied drive pulses and landing these inks on a recording medium or the like. An image or the like is formed on the recording medium by the collection of the plurality of dots. In such a configuration, the size of a pixel which is a structural unit of an image or the like is adjusted by increasing or decreasing the number of ink droplets ejected within a unit cycle. That is, multi-tone recording is possible by increasing or decreasing the number of ink droplets.

  However, for example, when high-speed printing is performed on a recording medium such as roll paper at a printing speed of about 1000 to 1500 cps (characters / second), the relative speed between the recording head and the recording medium becomes larger, so A plurality of ink droplets ejected from the same nozzle opening within a cycle may land at positions shifted from each other in the relative movement direction, and this landing position shift of the dots causes a decrease in image quality such as an image. It was.

  Therefore, in order to enable high-speed printing as described above, in the configuration in which the ink (ink droplet) is continuously ejected twice from the same nozzle opening within the unit cycle, the flying speed of the ink droplet to be ejected later is set first. There has been proposed a recording apparatus in which the ink droplets are combined with each other during flight (in the air) by making the ejection speed of the ejected ink droplets higher, and land on a recording medium as one ink droplet ( For example, see Patent Document 1).

JP 2003-175599 A

  On the other hand, in the recording apparatus that realizes high-speed printing as described above, the dot landing position is shifted at the intersection of the dot that forms one straight line and the dot that forms the other straight line, so that a concave portion is formed. May cause degradation. More specifically, for example, in the case where the character “MAKE” as shown in FIG. 7A is printed by transporting the recording medium in the direction of the arrow in the figure, the portion A is continuous at a timing that precedes in time. The end of the first line L1 extending in the vertical direction in the figure formed by the ejected ink droplets in the horizontal direction in the figure formed by the ink droplets ejected at the same timing following in time ( There is a case where an intersection with the second line L2 extending in the nozzle row direction) is formed. That is, in this case, the lower end of the first line L1 is stopped in contact with the second line L2. In this way, in the intersection portion where the other line is stopped by one line, the residual vibration in a specific pressure generating chamber forming a continuous dot (vertical first line L1 in the case of FIG. 7A). As a result, a dent of the line appears at the intersection.

  This phenomenon will be described in more detail with reference to FIGS. 7B and 7C. FIG. 7B and FIG. 7C are directions (lateral directions) intersecting the ink flying direction when ink droplets are ejected from the nozzle openings constituting the nozzle row toward the recording medium. 7 (b) is an ideal flight mode, and FIG. 7 (c) is an actual flight mode during high-speed printing.

  As shown in FIG. 7B, the first line L1 (for example, the vertical line in section A in FIG. 7A) retains the positional relationship as shown in the figure and continuously ejected ink droplets are recorded. The second line L2 (for example, the horizontal line in section A in FIG. 7A) formed by landing on the medium is an ink droplet ejected in a single shot while maintaining the positional relationship shown in the figure. When it is formed by landing on a recording medium, no problem occurs.

  On the other hand, the actual flight mode of ink droplets in this case is as shown in FIG. This is because, when ink droplets are ejected continuously, the flying speed of the subsequent ink droplets is affected by the residual vibration of the pressure generating chamber, and is larger than the flying velocity of the adjacent ink droplets in the nozzle row direction. Because it ends up. That is, at the intersection P between the first line L1 and the second line L2, the actual ink droplet flying position is lower than the reference position (the flying position of the adjacent ink droplet for single ejection) by a deviation amount ΔL. It will shift. In addition, the flying position of the single ejection ink droplet is a convex curve in FIG. 7C because of the influence of the crosstalk between the pressure generating chambers adjacent in the nozzle row direction. But it doesn't matter here.

  FIGS. 7B and 7C show the positions of the flying ink droplets. The first line L1 and the second line L2 are shown in FIGS. 7B and 7C. Strictly different from the shape shown in (2), the ink droplets are formed by landing on the recording medium. However, since almost the same shape is transferred to the recording medium, in the present specification, the two are equivalent. It will be described as something.

  Accordingly, when the above-described deviation ΔL of the flying position is transferred to the dots that land on the recording medium, a recess is formed at the intersection P between the first line L1 and the second line L2. That is, in the case shown in FIG. 7C, at the intersection P between the first line L1 (vertical line) and the second line L2 (horizontal line), below the lower end of the first line L1. Becomes a recess. Such a recess is not only in the case where the first line L1 and the second line L2 are orthogonal to each other, but at the intersection P in such a manner that one is stopped by the other, even if it intersects obliquely, there is a difference in degree. It is formed.

  Such a problem exists not only in an ink jet recording apparatus that ejects ink but also in a liquid ejecting apparatus that ejects liquid other than ink.

  In view of the above-described prior art, the present invention suppresses formation of a recess at the intersection of the first line and the second line and can contribute to improvement of product quality such as print quality and control thereof. It aims to provide a method.

An aspect of the present invention that achieves the above object is to generate pressure fluctuations in a nozzle row formed by a plurality of nozzle openings arranged in parallel in one direction, a pressure generation chamber communicating with each nozzle opening, and a liquid in each pressure generation chamber. A liquid ejecting head capable of discharging liquid from the nozzle opening by driving the pressure generating means, and a driving pulse for driving the pressure generating means to discharge liquid from the nozzle opening. Drive signal generating means for generating a drive signal including, and moving a recording medium relative to the liquid ejecting head in a direction intersecting the nozzle row by a moving means, and ejecting droplets from the nozzle openings to A liquid ejecting apparatus having control means for controlling to land on the recording medium, wherein the drive signal generating means includes a first driving unit that precedes within a unit period. A pulse and a second drive pulse that follows the first drive pulse and has a faster flight speed of the ejected droplets than in the case of the first drive pulse. A third drive pulse for ejecting droplets accompanied by satellite droplets within the unit period of time, and the control means causes the droplets to be ejected continuously in the relative movement direction of the recording medium. The end of the first line formed on the recording medium is a first line formed on the recording medium by droplets ejected from a plurality of nozzle openings in the nozzle row direction crossing the first line. While detecting the position of the intersection point when forming an intersection point with the line 2, droplets that land on points other than the intersection point are ejected by the first drive pulse and the second drive pulse, and the intersection point is also detected. Droplets to land, there is provided a liquid-jet apparatus characterized by by the third drive pulse is to control so as to eject droplets.
According to this aspect, the liquid droplets ejected by the second drive pulse follow the liquid droplets ejected by the first drive signal and merge in the air to be integrated into a large liquid droplet. While the liquid droplets ejected by the third drive pulse are landed on the medium, medium dots and small dots are formed on the recording medium by the preceding liquid droplets and the following satellite liquid droplets along the conveyance direction of the recording medium. Two continuous dots are formed on the side and the downstream side. Here, since the supply timing of the third drive pulse is made to correspond to the intersection position of the first line and the second line that are separately detected, the recess formed at the intersection portion is complemented with two dots. Can do.
As a result, it is possible to perform high quality printing or the like while suppressing the occurrence of recesses at the intersections.

  Here, the drive signal includes the first drive pulse followed by the second drive pulse in the unit cycle corresponding to a point other than the intersection, and the third drive cycle in the another unit cycle corresponding to the intersection. Those having a continuous waveform of the drive pulses can be suitably used. In this case, it is possible to appropriately switch and select the first to third drive pulses with one type of drive signal to discharge a desired droplet.

  The drive signal includes a first drive signal having the first drive pulse and the second drive pulse formed in the unit cycle, and the third drive signal formed in the unit cycle. A second drive signal having a drive pulse may be included. In this case, the first to third drive pulses can be appropriately switched and selected with two types of drive signals to discharge a desired droplet.

  Furthermore, it is desirable that the waveform of the second drive pulse and the waveform of the third drive pulse have the same shape. In this case, not only the abnormal ejection due to the third drive pulse can be reduced, but also the liquid droplets ejected from the adjacent nozzle openings in the nozzle row direction are greatly affected by crosstalk. In some cases, the influence of such crosstalk can be eliminated.

  The flying speed of the droplets ejected by the second driving pulse and the third driving pulse is 1.1 to 3.6 times the flying speed of the droplets ejected by the first driving pulse. It is desirable that it is set. In this case, droplets with satellite droplets can be discharged well.

Another aspect of the present invention includes a nozzle row formed by a plurality of nozzle openings arranged in parallel in one direction, and generates pressure fluctuations in the pressure generation chambers communicating with the nozzle openings and the liquid in the pressure generation chambers. Driving the pressure generating means to generate a driving signal including a driving pulse for discharging the liquid from the nozzle opening, and moving the recording medium to the liquid ejecting head in a direction crossing the nozzle row by the moving means. In the control method of a liquid ejecting apparatus that performs control so that droplets are ejected from the nozzle opening and landed on the recording medium while being relatively moved, the drive signal includes a first drive pulse that precedes within a unit cycle. And a second drive pulse that follows the first drive pulse and has a faster flying speed of the ejected droplets than in the case of the first drive pulse. In a unit cycle different from the cycle, a third drive pulse for ejecting droplets with satellite droplets is generated, and the droplets are continuously ejected in the relative movement direction of the recording medium. The end of the first line formed on the recording medium is a second formed on the recording medium by droplets ejected from a plurality of nozzle openings in the nozzle row direction crossing the first line. While detecting the position of the intersection point when forming an intersection point with the line, droplets that land on points other than the intersection point are ejected by the first drive pulse and the second drive pulse, and at the intersection point In the liquid ejecting apparatus control method, the droplets to be landed are controlled to be ejected by the third driving pulse.
According to this aspect, the droplet ejected by the third drive pulse is divided into two dots, a medium dot and a small dot, on the recording medium by the preceding droplet and the following satellite droplet in the conveyance direction of the recording medium. In addition, the liquid droplets can be continuously formed on the upstream side and the downstream side, and the liquid droplets are ejected by the third driving pulse corresponding to the intersection position of the first line and the second line that are separately detected. Therefore, the recess formed at the intersection can be complemented with two dots.

1 is a schematic perspective view showing a recording apparatus according to an embodiment of the present invention. FIG. 3 is a cross-sectional view illustrating an example of a recording head. FIG. 2 is a block diagram illustrating a control system of the recording apparatus illustrated in FIG. 1. It is a wave form diagram which shows an example of the drive signal in this form. It is explanatory drawing which shows the flight aspect of the ink droplet discharged in this form. It is a wave form diagram which shows the other example of the drive signal in this form. It is explanatory drawing for demonstrating a prior art.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a schematic perspective view showing an ink jet recording apparatus according to this embodiment. As shown in the figure, the ink jet recording apparatus I according to the present embodiment is a so-called line type recording in which the head unit 1 is fixed and printing is performed by transporting a recording sheet S such as paper as an ejection medium. Device. Specifically, the ink jet recording apparatus I includes an apparatus main body 8, a head unit 1 that includes a plurality of recording heads 2 and is fixed to the apparatus main body 8, a conveyance unit 5 that conveys a recording sheet S, and a head. A platen 4 that supports the opposite side of the printing surface of the recording sheet S facing each other in the unit 1 is provided.

  A plurality (eight in the figure) of the recording heads 2 are fixed in a staggered manner to the base plate 3 to form the head unit 1, and the nozzle openings 11 (see FIG. 2) of the recording head 2 are arranged in parallel (see FIG. 2). The head unit 1 is fixed to the apparatus main body 8 so that the Y direction in the middle intersects the conveyance direction of the recording sheet S (X direction in the figure).

  The conveying unit 5 includes a first conveying unit 6 and a second conveying unit 7 provided on both sides of the recording unit S in the conveying direction with respect to the head unit 1.

  The first transport unit 6 includes a drive roller 6a, a driven roller 6b, and a transport belt 6c wound around the drive roller 6a and the driven roller 6b. Similarly to the first transport unit 6, the second transport unit 7 includes a driving roller 7a, a driven roller 7b, and a transport belt 7c.

  Driving means such as a driving motor (not shown) are connected to the respective driving rollers 6a and 7a of the first conveying means 6 and the second conveying means 7, and the conveying belt 6c, The recording sheet S is conveyed on the upstream side and the downstream side of the head unit 1 by the rotational drive of 7c.

  In this embodiment, the first conveying means 6 and the second conveying means 7 constituted by the driving rollers 6a and 7a, the driven rollers 6b and 7b, and the conveying belts 6c and 7c are exemplified, but the recording sheet S is conveyed. You may further provide the holding means to hold | maintain on the belts 6c and 7c. As the holding unit, for example, a charging unit that charges the outer peripheral surface of the recording sheet S may be provided, and the recording sheet S charged by the charging unit may be adsorbed onto the conveying belts 6c and 7c by the action of dielectric polarization. . Further, as a holding unit, a pressing roller may be provided on the conveying belts 6c and 7c, and the recording sheet S may be sandwiched between the pressing roller and the conveying belts 6c and 7c.

  The platen 4 is made of a metal or resin having a rectangular cross section provided between the first transport unit 6 and the second transport unit 7 so as to face the head unit 1. The platen 4 supports the recording sheet S conveyed by the first conveying unit 6 and the second conveying unit 7 at a position facing the head unit 1.

  The platen 4 may be provided with a suction unit that sucks the conveyed recording sheet S on the platen 4. Examples of the suction means include a device that sucks and sucks the recording sheet S and a device that electrostatically sucks the recording sheet S by electrostatic force.

  In addition, although not shown, each storage head 2 of the head unit 1 is connected to an ink storage means such as an ink tank or an ink cartridge in which ink is stored so as to be able to supply ink. For example, the ink storage unit may be held on the head unit 1 or may be held at a position different from the head unit 1 in the apparatus main body 8.

  In such an ink jet recording apparatus I, the recording sheet S is transported by the transport unit 6, and printing is performed on the recording sheet S supported on the platen 4 by the head unit 1. The printed recording sheet S is conveyed by the conveying means 5.

  In the present embodiment, the head unit 1 having a plurality of recording heads 2 is mounted on the ink jet recording apparatus I. However, the present invention is not particularly limited to this, and one or a plurality of recording heads 2 are directly connected to the ink jet recording apparatus. It may be mounted on I. A plurality of head units 1 may be mounted on the ink jet recording apparatus I.

  FIG. 2 is a cross-sectional view of a main part for explaining the configuration of the recording head 2. The recording head 2 includes a case 13, a vibrator unit 14 housed in the case 13, a flow path unit 15 joined to the bottom surface (tip surface) of the case 13, and the like. The case 13 is made of, for example, an epoxy resin, and a housing empty portion 16 for housing the vibrator unit 14 is formed therein. The vibrator unit 14 includes a piezoelectric element 17 that functions as a kind of pressure generating means, a fixing plate 18 to which the piezoelectric element 17 is joined, and a flexible cable 19 for supplying a drive signal and the like to the piezoelectric element 17. ing. The piezoelectric element 17 is a laminated type produced by cutting a piezoelectric plate in which piezoelectric layers and electrode layers are alternately laminated into a comb-like shape, and has a longitudinal vibration mode that can expand and contract in a direction perpendicular to the lamination direction. It is a piezoelectric element.

  The flow path unit 15 is configured by joining a nozzle substrate 21 to one surface of the flow path substrate 20 and an elastic plate 22 to the other surface of the flow path substrate 20. The flow path unit 15 is provided with a manifold 23, an ink supply port 24, a pressure generation chamber 25, a nozzle communication port 26, and a nozzle opening 27. A series of ink flow paths from the ink supply port 24 to the nozzle opening 27 through the pressure generation chamber 25 and the nozzle communication port 26 are formed corresponding to each nozzle opening 27. Thus, a nozzle row is formed by a plurality of nozzle openings 27 arranged in parallel in the direction orthogonal to the paper surface of FIG.

  The nozzle substrate 21 is a plate made of a metal plate such as stainless steel, a silicon single crystal substrate, an organic plastic, or the like in which a plurality of nozzle openings 27 are formed in rows at a pitch (for example, 180 dpi) corresponding to the dot formation density. .

  The elastic plate 22 has a double structure in which an elastic film 29 is laminated on the surface of the support plate 28. In this embodiment, the elastic plate 22 is manufactured using a composite plate material in which a stainless plate, which is a kind of metal plate, is used as the support plate 28 and a resin film is laminated on the surface of the support plate 28 as an elastic film 29. The elastic plate 22 is provided with a diaphragm portion 30 that changes the volume of the pressure generating chamber 25. The elastic plate 22 is provided with a compliance portion 31 that seals a part of the manifold 23.

  The diaphragm portion 30 is produced by partially removing the support plate 28 by etching or the like. That is, the diaphragm portion 30 includes an island portion 32 to which the tip end surface of the piezoelectric element 17 is joined, and a thin elastic portion 33 that surrounds the island portion 32. The compliance portion 31 is produced by removing the support plate 28 in the region facing the opening surface of the manifold 23 by etching or the like, similarly to the diaphragm portion 30, and absorbs the pressure fluctuation of the liquid stored in the manifold 23. Functions as a damper.

  Since the tip end face of the piezoelectric element 17 is joined to the island part 32, the volume of the pressure generating chamber 25 can be changed by expanding and contracting the free end part of the piezoelectric element 17. As the volume changes, pressure fluctuations occur in the ink in the pressure generation chamber 25. The recording head 2 ejects ink droplets (a type of droplet) from the nozzle openings 27 using this pressure fluctuation.

  FIG. 3 is a block diagram showing a control system of the recording apparatus I according to this embodiment. As shown in the figure, the recording apparatus I is schematically configured by a printer controller 35 (a kind of control means in the present invention) and a print engine 36. The printer controller 35 includes an external interface (external I / F) 37 for inputting print data from an external device such as a host computer, a RAM 38 for storing various data, a control routine for various data processing, and the like. The stored ROM 39, a control unit 41 for controlling each unit, an oscillation circuit 42 for generating a clock signal, and a drive signal generating circuit 43 for generating a drive signal to be supplied to the recording head 2 (the drive signal generating means of the present invention) And an internal interface (internal I / F) 45 for outputting pixel data, drive signals, and the like obtained by developing print data for each dot to the recording head 2.

  For example, the control unit 41 in this embodiment is configured such that the end of the first line L1 (vertical line in the drawing) ends at the second line L2 (horizontal line in the drawing) as shown in FIG. The position of the intersection point P that makes contact is detected based on the image data. More specifically, the first formed on the recording sheet S by ejecting ink droplets continuously in the moving direction (X-axis direction in FIG. 1) of the recording sheet S (see FIG. 1; the same applies hereinafter). The position of the intersection point P when the end of the line L1 is in contact with the second line L2 formed on the recording sheet S by the ink droplets ejected from the plurality of nozzle openings 27 in the nozzle row direction is detected. In this case, at the intersection P, as shown in FIG. 7B, when the first line L1 extends in the vertical direction and the second line L2 extends in the horizontal direction, the two are orthogonal to each other. It is not limited to the intersection point P to be formed. All intersection points P formed between the first line L1 and the second line L2 so that one end is in contact with the other are included. Even in this case, when the first line L1 and the second line L2 are formed by high-speed printing without taking any measures, a recess is formed at the intersection P due to residual vibration in the pressure generation chamber 25. Because it will end up.

  Therefore, the control unit 41 outputs a head control signal for controlling the operation of the recording head 2 to the recording head 2 and outputs a control signal for generating the driving signal COM to the driving signal generation circuit 43. Thus, each part of the recording head 2 is controlled so that ink droplets that land on points other than the intersection point P and ink droplets that land on the intersection point P are separated. A specific description regarding this point will be described later.

  Here, the head control signal is, for example, a transfer clock CK, pixel data SI, a latch signal LAT, and a change (channel) signal CH. The latch signal LAT and the change signal CH define the supply timing of each pulse signal constituting the drive signal COM.

  The print engine 36 includes the recording head 2 and the conveying unit 5. Here, the recording head 2 includes a plurality of shift registers (SR) 46, latches 47, decoders 48, level shifters (LS) 49, switches 50, and piezoelectric elements 17 corresponding to the respective nozzle openings 27. Pixel data (SI) from the printer controller 35 is serially transmitted to the shift register 46 in synchronization with the clock signal (CK) from the oscillation circuit 42. The conveying unit 5 supplies and conveys the recording sheet S.

  A latch 47 is electrically connected to the shift register 46. When a latch signal (LAT) from the printer controller 35 is input to the latch 47, the pixel data of the shift register 46 is latched. The pixel data latched by the latch 47 is input to the decoder 48. The decoder 48 translates 2-bit pixel data to generate pulse selection data. The pulse selection data in this embodiment is composed of data of a total of 2 bits.

  Then, the decoder 48 outputs pulse selection data to the level shifter 49 when receiving the latch signal (LAT) or the change signal (CH). In this case, the pulse selection data is input to the level shifter 49 in order from the upper bit. The level shifter 49 functions as a voltage amplifier. When the pulse selection data is “1”, the level shifter 49 outputs an electric signal boosted to a voltage capable of driving the switch 50, for example, a voltage of about several tens of volts. The pulse selection data “1” boosted by the level shifter 49 is supplied to the switch 50. The drive signal COM from the drive signal generation circuit 43 is supplied to the input side of the switch 50, and the piezoelectric element 17 is connected to the output side of the switch 50.

  The pulse selection data controls the operation of the switch 50, that is, the supply of the ejection pulse in the drive signal to the piezoelectric element 17. For example, during a period when the pulse selection data input to the switch 50 is “1”, the switch 50 is in a connected state, and the corresponding ejection pulse is supplied to the piezoelectric element 17, and follows the waveform of the ejection pulse. The potential level of the piezoelectric element 17 changes. On the other hand, during the period when the pulse selection data is “0”, the level shifter 49 does not output an electrical signal for operating the switch 50. For this reason, the switch 50 is disconnected and no ejection pulse is supplied to the piezoelectric element 17.

  FIG. 4 is a diagram for explaining an example of the configuration of the drive signal COM generated by the drive signal generation circuit 43. The drive signal COM in the present embodiment is a series of signals having a plurality of ejection drive pulses within unit periods T1 and T2 divided by timing signals (for example, LAT signals), that is, within the repetition period of the drive signal COM. The drive signal COM in the present embodiment includes a first drive pulse P1 generated first in the unit cycle T1 and a subsequent second drive pulse P2 generated following the first drive pulse P1. The third drive pulse P3 is generated in another unit cycle T2 and the flying speed of the ink droplet is set so as to accompany the satellite droplet. Here, the second drive pulse P2 and the third drive pulse P3 in this embodiment are configured to have the same waveform. Therefore, the description regarding the second drive pulse P2 also applies to the third drive pulse P3 as it is. Therefore, the overlapping description regarding the third drive pulse P3 is omitted.

  In this embodiment, the second drive pulse P2 is configured to be faster than the flying speed of the ink droplet ejected by the first drive pulse P1. That is, the first drive pulse P1 includes the first preliminary expansion part p1a, the first expansion hold part p2a, the first contraction part p3a, and the first contraction hold part p4a. The first preliminary expansion portion p1a is a waveform portion in which the potential changes (rises) in a positive direction with a constant gradient from the reference potential VB to the expansion potential VH, and the first expansion hold portion p2a is the first preliminary expansion portion. The waveform portion is constant at the expansion potential VH which is the terminal potential of p1a. The first contraction portion p3a is a waveform portion in which the potential changes (falls) in the negative direction from the expansion potential VH to the contraction potential VL, and the first contraction hold portion p4a is a waveform portion that is constant at the contraction potential VL. The first return expansion portion p5a is a waveform portion that returns the potential from the contraction potential VL to the reference potential VB.

  Here, the time width of the first expansion hold part p2a in the first drive pulse P1 is longer than the time width of the second expansion hold part p2b in the subsequent second drive pulse P2. As a result, the pressure vibration generated during the expansion of the pressure generation chamber 25 by the first preliminary expansion portion p1a is attenuated to some extent, and then the pressure generation chamber 25 is contracted by the next first contraction portion p3a. Compared to the case of the second driving pulse P2, the flying speed of the ink droplets ejected from the nozzle opening 27 becomes slower.

  On the other hand, the second drive pulse P2 includes the second preliminary expansion part p1b, the second expansion hold part p2b, the second contraction part p3b, the second contraction hold part p4b, and the second return expansion. Part p5b. The second pre-expansion part p1b is a waveform part in which the potential rises in a positive direction with a constant gradient from the reference potential VB to the expansion potential VH, and the second expansion hold part p2b is the end of the second pre-expansion part p1b It is a waveform portion that is held constant at an expansion potential VH that is a potential. The second contraction portion p3b is a waveform portion in which the potential drops in the negative direction from the expansion potential VH to the contraction potential VL, and the second contraction hold portion p4b is a waveform portion that is constant at the contraction potential VL. Further, the second return expansion portion p5b is a waveform portion that returns the potential from the contraction potential VL to the reference potential VB.

  Here, the second contraction part p3b holds the first contraction element p3ba whose potential drops in the negative direction from the expansion potential VH and the intermediate hold potential VMH that is the terminal potential of the first contraction element p3ba for a certain period of time. It is characterized by comprising an intermediate hold element p3bb and a second contraction element p3bc whose potential drops in the negative direction from the intermediate hold potential VMH. That is, the second contraction part p3b is configured such that the potential change stops for a short time while the potential changes from the expansion potential VH to the contraction potential VL. Further, the potential gradient (potential change amount per unit time) of the second contraction element p3bc is set to be steeper than the potential gradient of the first contraction element p3ba.

  As described above, the time width of the second expansion hold part p2b in the second drive pulse P2 is shorter than the time width of the first expansion hold part p2a in the preceding first drive pulse P1. Since the pressure generation chamber 25 is contracted by the second contraction portion p3b using the pressure vibration generated when the pressure generation chamber 25 is expanded by the second preliminary expansion portion p1b, the first drive pulse Compared with the case of P1, the flying speed of the ink droplet ejected from the nozzle opening 27 is increased.

  The drive signal COM is divided into unit periods T1 and T2 by a latch signal LAT (see FIG. 4B), and the second and third drive signals P2 and P3 are divided by a change signal CH (see FIG. 4C). Selected. Here, when the position of the intersection point P is detected by the control unit 41, the change signal CH of the change signal CH so that the ink droplet I2 by the third drive pulse P3 is ejected to the position corresponding to the detection position in the unit cycle T2. Supply timing is controlled.

  In this embodiment, as described above, the flying speed of the ink droplets ejected by the first drive pulse P1 is slower than the flying speed of the ink droplets ejected by the second drive pulse P2, so FIG. ), The ink droplet I12 accompanied by the satellite droplet I13 ejected by the second drive signal COM2 is integrated following the ink droplet I11 ejected by the first drive pulse P1. That is, both of them, including the satellite droplet I13, are combined in the air, and become a large ink droplet I1 and land on the recording sheet S. In this case, the flying speed can be, for example, about 4 m / s for the ink droplet I11 and about 7 m / s for the ink droplet I12. By setting the flying speed like this, the ink droplet I12 ejected later is combined with the preceding ink droplet I11 in the air to reach a flying speed of about 6 m / s, and the satellite droplet I13 is caught up and integrated. The desired large dots can be formed by landing.

  On the other hand, the ink droplet I2 ejected by the third drive pulse P3 is landed on the recording sheet S while the preceding ink droplet I12 maintains the flying speed (for example, 7 m / s) at the time of ejection, and the following satellites. The droplet I13 is also landed on the recording sheet at substantially the same flying speed. That is, in this case, the medium dots formed on the recording sheet S by the ink droplets I12 and the small dots formed by the satellite droplets I13 are aligned in the front-rear direction in the conveyance direction of the recording sheet S without being combined in the air. It is formed.

  FIG. 5 shows how ink droplets fly when printing similar to that shown in FIG. 7 is performed using the drive signal COM, that is, when the first line L1 is stopped in contact with the second line L2. Shown in FIG. 5 is a view showing a flight mode corresponding to FIGS. 7B and 7C, and similarly to FIGS. 7B and 7C, the recording sheet is formed from each nozzle opening 27 constituting the nozzle row. FIG. 6 is a view of a state when ink droplets I1 and I2 are ejected toward S, as viewed from a direction (lateral direction) intersecting an ink flying direction.

  As shown in the figure, in this embodiment, dots are formed when ink droplets I2 (I12, I13) ejected by the third drive pulse P3 land on the recording sheet S in accordance with the position of the intersection P. . Since the dots formed at this time have a shape transferred upside down in FIG. 5 to the recording sheet S, the intersection P is complemented by the ink droplet I12 and the satellite droplet I13 following the ink droplet I12. In other words, since the portion that has conventionally been a concave portion is complemented by two medium dots and small dots, the formation of the concave portion can be suppressed.

  Although the embodiment of the present invention has been described above, the basic configuration of the present invention is not limited to the above-described one. For example, the drive signal COM need not be limited to that shown in FIG. The first drive signal COM1 including the first drive pulse P1 and the second drive pulse P2 and the second drive signal P3 including the third drive pulse P3 are appropriately switched and applied to the piezoelectric element 17. Even so, it is possible to obtain the effect of suppressing the recesses at the intersection P as shown in FIG. In this case, the continuous drive uses the first drive signal, and the dot at the intersection P uses the second drive signal.

  The waveforms of the first drive signal COM1 and the second drive signal COM2 in this case are shown in FIG. As shown in the figure, the first and second drive pulses P1, P2 are selected in the unit cycle T1, and the third drive pulse P3 is selected in the unit cycle T2. In this example, the first to third drive pulses P1, P2, and P3 are the same as those shown in FIG.

  In FIG. 6, the same parts as those in FIG. 4 are denoted by the same reference numerals, and redundant description is omitted.

  It is not essential to configure the third drive pulse P3 in the same manner as the second drive pulse P2 as in the above embodiment. The only essential component requirement for the third drive pulse P3 is that the ejected ink droplets are accompanied by satellite droplets. Usually, satellite droplets can be formed if a flight speed of 5 m / s or more can be secured.

  However, when the second drive pulse P2 and the third drive pulse P3 have the same waveform as in the above embodiment, abnormal ejection of the third drive pulse P3 can be reduced. In addition, a third drive pulse signal that is significantly different from the second drive pulse P2 from the nozzle openings 27 adjacent in the nozzle row direction to the nozzle openings 27 that eject ink droplets by the first and second drive pulses P1 and P2. When the ink droplet by P3 is ejected, there is a possibility that the third drive pulse P3 is affected by the crosstalk of the second drive pulse P2.

  On the other hand, if the waveforms of the second and third drive pulses P2 and P3 are the same, such a crosstalk problem does not occur. Incidentally, when a drive pulse having a different waveform is supplied to the piezoelectric element 17 (see FIG. 2) generally corresponding to the adjacent nozzle opening 27, the behavior of the ink droplet during flight changes due to the influence.

  Furthermore, if the flying speed is about 1.1 to 3.6 times that of the first drive pulse P1, the desired satellite droplet I13 can be suitably formed.

  In the above embodiment, the longitudinal vibration type piezoelectric element 17 is used as the pressure generating means. However, the present invention is not limited to this, and for example, a lower electrode, a piezoelectric layer, and an upper electrode are stacked. A flexural deformation type piezoelectric element may be used. Incidentally, when the longitudinal vibration type piezoelectric element 17 is used, the piezoelectric element 17 contracts in the longitudinal direction by charging and expands the pressure generating chamber 25, and the piezoelectric element 17 expands in the longitudinal direction by discharging and contracts the pressure generating chamber 25. Let On the other hand, when a bending deformation type piezoelectric element is used as the pressure generating means, the piezoelectric element is deformed to the pressure generating chamber 25 side by charging to contract the pressure generating chamber 25, and the piezoelectric element 17 is discharged by discharging. The pressure generating chamber 25 is expanded by being deformed to the side opposite to the pressure generating chamber 25. A drive signal for driving such a piezoelectric element has a shape in which the potential polarity of the drive signal described above is inverted.

  Further, as a pressure generating means, a so-called electrostatic actuator that generates static electricity between the diaphragm and the electrode, deforms the diaphragm by electrostatic force, and discharges droplets from the nozzle opening 27 may be used. Good.

  In the recording apparatus I described above, the recording head 2 is fixed, and a recording medium such as the recording sheet S is moved in a direction orthogonal to the nozzle array direction to perform printing, but a so-called line type is used. Of course, the present invention can also be applied to a so-called serial type recording apparatus in which the head is mounted on the carriage and moves in the main scanning direction.

  Furthermore, the present invention is intended for a wide range of liquid jet heads in general, for example, for manufacturing recording heads such as various ink jet recording heads used in image recording apparatuses such as printers, and color filters such as liquid crystal displays. The present invention can also be applied to a coloring material ejecting head, an organic EL display, an electrode material ejecting head used for forming electrodes such as an FED (field emission display), a bioorganic matter ejecting head used for biochip manufacturing, and the like. Needless to say, a liquid ejecting apparatus including such a liquid ejecting head is not particularly limited.

  I recording apparatus, 2 recording head, 17 piezoelectric element, 25 pressure generating chamber, 27 nozzle opening, 35 printer controller, 41 control unit, 43 driving signal generating circuit, COM, COM1, COM2 driving signal, P1 first driving pulse, P2 second driving pulse, P3 third driving pulse, L1 first line, L2 second line, I1, I2 ink droplet, S recording sheet

Claims (6)

A nozzle array formed by a plurality of nozzle openings arranged in parallel in one direction, a pressure generating chamber communicating with each nozzle opening, and a pressure generating means for causing a pressure fluctuation in a liquid in each pressure generating chamber; A liquid jet head capable of discharging liquid from the nozzle opening by driving means;
Drive signal generating means for generating a drive signal including a drive pulse for driving the pressure generating means to eject liquid from the nozzle openings, and moving the recording medium in a direction crossing the nozzle row by the moving means A liquid ejecting apparatus comprising: a control unit that controls the liquid droplets to be ejected from the nozzle openings and landed on the recording medium while moving relative to the ejecting head;
In the unit cycle, the drive signal generation means has a first drive pulse that precedes the first drive pulse, and the flying speed of the ejected droplet is faster than that of the first drive pulse. A second driving pulse is generated, and a third driving pulse for discharging a droplet accompanied by a satellite droplet is generated in a unit period different from the unit period.
Further, the control means crosses the first line at the end of the first line formed on the recording medium by continuously ejecting droplets in the relative movement direction of the recording medium. And detecting the position of the intersection when forming a point of intersection with a second line formed on the recording medium with droplets ejected from a plurality of nozzle openings in the nozzle row direction. The liquid droplets to be landed are ejected by the first drive pulse and the second drive pulse, and the liquid droplets landed at the intersection are controlled to be ejected by the third drive pulse. A liquid ejecting apparatus characterized by the above. The liquid ejecting apparatus according to claim 1,
The drive signal includes the first drive pulse followed by the second drive pulse in the unit period corresponding to a point other than the intersection, and the third drive pulse in the other unit period corresponding to the intersection. A liquid ejecting apparatus having a continuous waveform. The liquid ejecting apparatus according to claim 1,
The drive signal includes a first drive signal having the first drive pulse and the second drive pulse formed within the unit period, and the third drive pulse formed within the unit period. And a second drive signal. In the liquid ejecting apparatus according to any one of claims 1 to 3,
The liquid ejection apparatus, wherein the waveform of the second drive pulse and the waveform of the third drive pulse have the same shape. In the liquid ejecting apparatus according to any one of claims 1 to 4,
The flying speed of the droplets ejected by the second driving pulse and the third driving pulse is set to be 1.1 to 3.6 times the flying speed of the droplets ejected by the first driving pulse. A liquid ejecting apparatus. A nozzle row formed by a plurality of nozzle openings arranged in parallel in one direction, driving pressure generating chambers communicating with the nozzle openings and pressure generating means for causing pressure fluctuations in the liquid in the pressure generating chambers; The nozzle opening generates a driving signal including a driving pulse for discharging liquid from the nozzle opening, and moves the recording medium relative to the liquid ejecting head in a direction intersecting the nozzle row by a moving unit. In the control method of the liquid ejecting apparatus for controlling the liquid ejecting liquid droplets to land on the recording medium,
In the unit cycle, the drive signal follows the preceding first drive pulse and the first drive pulse, and the second flying speed of the ejected droplet is faster than that in the case of the first drive pulse. And a third driving pulse for discharging a droplet with satellite droplets in a unit cycle different from the unit cycle,
Further, the end of the first line formed on the recording medium by continuously ejecting droplets with respect to the relative movement direction of the recording medium intersects the first line in the nozzle row direction. The position of the intersection point in the case where an intersection point is formed with the second line formed on the recording medium by droplets discharged from a plurality of nozzle openings, while the droplet is landed on a point other than the intersection point Is controlled so that the liquid droplets ejected by the first driving pulse and the second driving pulse are ejected by the third driving pulse. Control method.

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