JP2018047625A - Liquid injection device and driving signal determination method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid injection device which suppresses elongated printing time while being capable of suppressing deterioration in discharge characteristics of droplets, and can reduce a scale of a circuit and costs, and a driving signal correction method.SOLUTION: A liquid injection device comprises: a liquid injection head comprising a nozzle array having a plurality of nozzles, a flow passage communicating with the nozzles, and a driving element generating a pressure change with respect to liquid in the flow passage; a driving signal generation section 216 generating a driving signal; and a printer controller 210 dividing printing data supplied corresponding to the same nozzle array, the printing data determining presence/absence of a shot of a droplet from each nozzle constituting the nozzle array in association with relative movement of the liquid injection head with respect to a medium, into a plurality of regions including the shot number of continuous two shots or more and being capable of executing a drive waveform correction mode capable of correcting a drive waveform supplied to the driving element according to the simultaneous shot number in the nozzle array for each region divided.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a liquid ejecting apparatus including a liquid ejecting head that ejects liquid from a nozzle and a drive signal correction method, and more particularly to an ink jet recording apparatus and a drive signal correcting method that eject ink as liquid.

  As the liquid ejecting apparatus, for example, an ink jet recording apparatus that performs printing on a medium such as paper or a recording sheet by ejecting ink droplets as a liquid is known.

  An ink jet recording head mounted on an ink jet recording apparatus includes a flow path communicating with a nozzle and a drive element such as a piezoelectric actuator that causes a pressure change in ink in the flow path, and drives the drive element. Thus, a pressure change is generated in the ink in the flow path, and ink droplets are ejected from the nozzles.

  However, there is a problem that when the number of ink droplets ejected simultaneously, that is, the number of simultaneous shots is large and the number of drive elements driven simultaneously increases, the drive waveform deteriorates. In other words, when the number of drive elements that are driven simultaneously increases, the current flowing through the drive circuit and wiring increases and the load increases, so that the slope of the voltage is lower than the drive waveform to be supplied to the drive elements, The drive waveform is deteriorated such that the assumed voltage is not reached.

  For this reason, two drive signal generators for generating drive signals including drive waveforms are provided, and the number of drive waveforms driven simultaneously is reduced by shifting the timing of the drive waveforms generated by the two drive signal generators. Thus, a method for suppressing the deterioration of the drive waveform has been proposed (see, for example, Patent Document 1).

  Further, a method has been proposed in which the drive waveform supplied to the drive element is monitored, and the drive waveform is corrected so that the drive waveform approaches the original drive waveform to be supplied, thereby suppressing the deterioration of the drive waveform (for example, Patent Document 2). reference).

JP 2002-120366 A JP 2010-5966 A

  However, when a plurality of drive signal generation units are provided as in Patent Document 1, there is a problem that the scale of the circuit increases and the cost increases.

  In addition, when the drive waveform is monitored and corrected as in Patent Document 2, the drive waveform is corrected for each shot of the ink droplet, and the number of times the drive waveform is corrected increases, and the correction takes time. There is a problem that printing takes time.

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

  In view of such circumstances, the present invention can suppress the deterioration of droplet discharge characteristics, suppress an increase in printing time, reduce the circuit scale, and reduce the cost. An object of the present invention is to provide a liquid ejecting apparatus and a driving signal correction method.

  An aspect of the present invention that solves the above problem is that a nozzle row having a plurality of nozzles that eject droplets, a flow path that communicates with the nozzles, and a drive signal that includes a drive waveform are supplied. Print data supplied corresponding to the same nozzle row, a liquid jet head including a drive element that causes a pressure change to the liquid, a drive signal generation unit that generates the drive signal, The print data for determining the presence or absence of droplet shots from the nozzles constituting the nozzle row accompanying the relative movement of the liquid ejecting head with respect to the medium is divided into a plurality of regions including the number of consecutive shots of two or more. A control unit capable of executing a drive waveform correction mode capable of correcting the drive waveform supplied to the drive element according to the number of simultaneous shots in the nozzle row for each of the divided regions; Lying in the liquid-jet apparatus characterized that Bei.

  In this aspect, by correcting the drive waveform according to the number of simultaneous shots, it is possible to suppress variations in the liquid ejection characteristics due to increase / decrease in the number of simultaneous shots, and to reduce print quality due to variations in the liquid ejection characteristics. Can be suppressed. Further, since the drive waveform is corrected for each region including the number of continuous shots of two or more print data, the time required for correcting the drive waveform can be shortened and the printing time can be shortened. Furthermore, since it is possible to correct a drive signal generated from one drive signal generation unit and suppress variations in liquid ejection characteristics due to increase / decrease in the number of simultaneous shots, a plurality of drive signals for generating different timing signals can be generated. A drive signal generator is not required. Therefore, cost can be reduced and downsizing can be achieved.

  Here, it is preferable that the print data includes data for determining a size of a droplet ejected from the nozzle. According to this, the driving waveform for ejecting small droplets, which are likely to deteriorate due to the increase in the number of simultaneous shots, is corrected based on the number of simultaneous shots, thereby effectively suppressing variations in ejection characteristics of small droplets. it can.

  Further, the liquid ejecting head is provided so as to be movable in a direction orthogonal to the conveyance direction of the medium, and the divided area is a unit of reciprocating movement in the movable direction of the liquid ejecting head. Are preferably divided as follows. According to this, the drive waveform can be corrected while the medium is transported in the transport direction, and it is not necessary to interrupt printing by correcting the drive waveform, and the printing time can be shortened.

  Further, it is preferable that the control unit executes the drive waveform correction mode in accordance with a print mode that defines a dot size. According to this, it is possible to improve the print quality by executing the drive waveform correction mode in the print mode for printing small dots, and not to execute the drive waveform correction mode in the print mode for printing large dots. Thus, the printing time can be shortened by the amount that the drive waveform is not corrected.

  Further, the liquid ejecting head is provided so as to be movable in a direction orthogonal to the conveyance direction of the medium, and the liquid ejecting head is attached to the medium only in one of the forward path and the return path in the movable direction. The unidirectional printing for printing and the bidirectional printing for printing on the medium by reciprocating in the movable direction are provided so as to be capable of printing, and the control unit is configured to perform the driving waveform correction mode in the unidirectional printing. Is preferably performed. According to this, in the bi-directional printing, the drive waveform is not corrected, and the drive waveform is corrected only in the case of the unidirectional printing, thereby effectively improving the print quality of the unidirectional printing in which the print quality is easily deteriorated. be able to.

  Furthermore, according to another aspect of the present invention, liquid in the flow path is provided by supplying a nozzle row having a plurality of nozzles for ejecting liquid droplets, a flow path communicating with the nozzles, and a drive signal including a drive waveform. Print data supplied corresponding to the same nozzle row to a liquid ejecting head having a drive element that causes a pressure change with respect to the medium, and at least relative to the medium of the liquid ejecting head The printing data for determining the presence or absence of the shot of the droplet from the nozzle is divided into a plurality of areas including the number of shots of two or more shots, and according to the number of simultaneous shots of the driving element for each of the divided areas The drive signal correction method includes correcting the drive waveform supplied to the drive element.

  In this aspect, by correcting the drive waveform according to the number of simultaneous shots, it is possible to suppress variations in the liquid ejection characteristics due to increase / decrease in the number of simultaneous shots, and to reduce print quality due to variations in the liquid ejection characteristics. Can be suppressed. Further, since the drive waveform is corrected for each region including the number of continuous shots of two or more print data, the time required for correcting the drive waveform can be shortened and the printing time can be shortened. Furthermore, since it is possible to correct a drive signal generated from one drive signal generation unit and suppress variations in liquid ejection characteristics due to increase / decrease in the number of simultaneous shots, a plurality of drive signals for generating different timing signals can be generated. A drive signal generator is not required. Therefore, cost can be reduced and downsizing can be achieved.

It is the schematic of a recording device. FIG. 3 is an exploded perspective view of a recording head. FIG. 3 is a plan view of a main part of the recording head. FIG. 3 is a cross-sectional view of a recording head. FIG. 3 is a block diagram illustrating a control configuration of a recording apparatus. FIG. 3 is a diagram illustrating an electrical configuration of a recording head. It is a drive waveform which shows a drive signal. It is explanatory drawing of the procedure which applies a drive pulse to a drive element. It is a figure explaining deterioration of a drive waveform. It is a graph which shows the relationship between the number of simultaneous shots, and flight speed. It is a figure explaining printing data. It is a figure which shows a printing result. It is a flowchart explaining the drive signal correction method. It is a drive waveform explaining the correction method of the 2nd ejection drive pulse. It is a drive waveform explaining deterioration of the corrected 2nd ejection drive pulse. It is a drive waveform explaining the correction method of the 2nd ejection drive pulse. It is a drive waveform explaining deterioration of the corrected 2nd ejection drive pulse. It is a drive waveform explaining the correction method of the 2nd ejection drive pulse. It is a drive waveform explaining deterioration of the corrected 2nd ejection drive pulse. It is a drive waveform explaining the correction method of the 2nd ejection drive pulse. It is a drive waveform explaining deterioration of the corrected 2nd ejection drive pulse.

Hereinafter, the present invention will be described in detail based on embodiments.
(Embodiment 1)
FIG. 1 is a diagram illustrating a schematic configuration of an ink jet recording apparatus which is an example of a liquid ejecting apparatus according to Embodiment 1 of the invention.

  As shown in the drawing, an ink jet recording apparatus 500 includes an ink jet recording head 1 (hereinafter also referred to as a recording head 1) that ejects ink as a liquid. The recording head 1 is mounted on a carriage 3, and the carriage 3 is provided on a carriage shaft 5 attached to the apparatus main body 4 so as to be movable in the axial direction of the carriage shaft 5. The carriage 3 is detachably provided with an ink cartridge 2 constituting a liquid supply means.

  Then, the driving force of the driving motor 6 is transmitted to the carriage 3 via a plurality of gears and a timing belt 7 (not shown), so that the carriage 3 on which the recording head 1 is mounted is moved along the carriage shaft 5. On the other hand, the apparatus main body 4 is provided with a conveyance roller 8 as a conveyance means, and a recording sheet S that is a medium such as paper on which ink is landed is conveyed by the conveyance roller 8. Note that the conveyance means for conveying the recording sheet S is not limited to the conveyance roller, and may be a belt, a drum, or the like. In the present embodiment, the conveyance direction of the recording sheet S is referred to as a first direction X. The moving direction of the carriage 3 along the carriage shaft 5 is referred to as a second direction Y. Incidentally, the carriage 3 has a home position at one end of the carriage shaft 5, and a cleaning means (not shown) for cleaning the liquid ejecting surface of the recording head 1 is provided at the home position. Examples of the cleaning unit include a suction unit that sucks ink from the nozzles of the recording head 1 and a wiping unit that wipes a liquid ejection surface on which the nozzles are opened with a wiper blade.

  In such an ink jet recording apparatus 500, the recording sheet S is conveyed in the first direction X with respect to the recording head 1, and the carriage 3 is moved in the second direction Y with respect to the recording sheet S, while the recording head is moved. By ejecting ink droplets from one nozzle, so-called printing is performed in which ink is landed over substantially the entire surface of the recording sheet S.

  Here, an example of the recording head 1 mounted on the ink jet recording apparatus 500 will be described with reference to FIGS. 2 is an exploded perspective view of an ink jet recording head that is an example of a liquid jet head according to Embodiment 1 of the present invention. FIG. 3 is a plan view of a flow path member of the ink jet recording head. 4 is a cross-sectional view taken along line AA ′ of FIG. In the present embodiment, for each direction of the recording head 1, the direction when the recording head 1 is mounted on the ink jet recording apparatus 500, that is, the first direction X, the second direction Y, and the third direction Z is used. explain. Of course, the arrangement of the recording head 1 in the ink jet recording apparatus 500 is not limited to the following.

  As shown in the figure, the flow path forming substrate 10 constituting the recording head 1 of the present embodiment has a flow path partitioned by a plurality of partition walls by anisotropic etching from one side in the third direction Z. The pressure generating chambers 12 constituting a part of the nozzles are arranged in parallel along the first direction X in which a plurality of nozzles 21 for discharging ink are arranged in parallel. Further, the flow path forming substrate 10 includes a plurality of rows in which the pressure generation chambers 12 are arranged in parallel in the first direction X, and in this embodiment, two rows are arranged in parallel in the second direction Y.

  On one side of the flow path forming substrate 10 in the third direction Z, the communication plate 15 and the nozzle plate 20 are sequentially stacked.

  The communication plate 15 is provided with a nozzle communication path 16 that communicates the pressure generating chamber 12 and the nozzle 21. The communication plate 15 has a larger area than the flow path forming substrate 10, and the nozzle plate 20 has a smaller area than the flow path forming substrate 10. By providing the communication plate 15 in this manner, the nozzle 21 of the nozzle plate 20 and the pressure generating chamber 12 can be separated from each other, so that the ink in the pressure generating chamber 12 is the amount of moisture in the ink generated by the ink near the nozzle 21. Less susceptible to thickening due to evaporation. In addition, since the nozzle plate 20 only needs to cover the opening of the nozzle communication passage 16 that communicates the pressure generating chamber 12 and the nozzle 21, the area of the nozzle plate 20 can be made relatively small, and the cost can be reduced. Can do. In the present embodiment, the surface on which the nozzles 21 of the nozzle plate 20 are opened and ink droplets are ejected is referred to as a liquid ejecting surface 20a.

  The communication plate 15 is provided with a first manifold portion 17 and a second manifold portion 18 that constitute a part of the manifold 100.

  The first manifold portion 17 is provided through the communication plate 15 in the third direction Z.

  Further, the second manifold portion 18 is provided to open to the nozzle plate 20 side of the communication plate 15 without penetrating the communication plate 15 in the third direction Z.

  Further, the communication plate 15 is provided with a supply communication passage 19 that communicates with one end portion in the second direction Y of the pressure generation chamber 12 independently of each of the pressure generation chambers 12. The supply communication path 19 communicates the second manifold portion 18 and the pressure generation chamber 12. That is, the supply communication path 19 is arranged in parallel with the manifold 100 in the first direction X.

  In the nozzle plate 20, nozzles 21 communicating with the pressure generation chambers 12 through the nozzle communication passages 16 are formed. The nozzles 21, which eject the same kind of ink (liquid), are arranged in parallel in the first direction X to form a nozzle row. Two nozzle rows composed of the nozzles 21 arranged in parallel in the first direction X are formed in the second direction Y.

  On the other hand, a diaphragm 50 is formed on the surface of the flow path forming substrate 10 opposite to the communication plate 15. In the present embodiment, an elastic film 51 made of silicon oxide provided on the flow path forming substrate 10 side and an insulator film 52 made of zirconium oxide provided on the elastic film 51 are provided as the diaphragm 50. I made it. The liquid flow path such as the pressure generation chamber 12 is formed by anisotropically etching the flow path forming substrate 10 from the surface side where the nozzle plate 20 is joined, and the other surface of the pressure generation chamber 12 is It is defined by the elastic film 51.

  A piezoelectric actuator 300 having a first electrode 60, a piezoelectric layer 70, and a second electrode 80 is provided on the vibration plate 50 of the flow path forming substrate 10. In the present embodiment, the piezoelectric actuator 300 is a drive element that causes a pressure change in the ink in the pressure generation chamber 12. Here, in the present embodiment, the first electrode 60 is separated for each pressure generation chamber 12 and constitutes an individual electrode that is independent for each active part described later in detail. The first electrode 60 is formed with a width narrower than the width of the pressure generation chamber 12 in the second direction Y of the pressure generation chamber 12. That is, in the first direction X of the pressure generation chamber 12, the end portion of the first electrode 60 is located inside the region facing the pressure generation chamber 12. In the second direction Y, both end portions of the first electrode 60 are extended to the outside of the pressure generation chamber 12.

  The piezoelectric layer 70 is continuously provided in the first direction X so that the second direction Y has a predetermined width. The width of the piezoelectric layer 70 in the second direction Y is wider than the length of the pressure generation chamber 12 in the second direction Y. Therefore, in the second direction Y of the pressure generation chamber 12, the piezoelectric layer 70 is provided to the outside of the pressure generation chamber 12.

  In the second direction Y of the pressure generating chamber 12, the end of the piezoelectric layer 70 on the ink supply path side is located outside the end of the first electrode 60. That is, the end portion of the first electrode 60 is covered with the piezoelectric layer 70. The end of the piezoelectric layer 70 on the nozzle 21 side is located on the inner side (the pressure generation chamber 12 side) than the end of the first electrode 60, and the end of the first electrode 60 on the nozzle 21 side is The piezoelectric layer 70 is not covered.

The piezoelectric layer 70 is made of a piezoelectric material of the oxide having a polarization structure formed on the first electrode 60, for example, it may consist of a perovskite oxide represented by the general formula ABO _3, lead containing lead For example, a lead-based piezoelectric material or a lead-free piezoelectric material containing no lead can be used.

  In such a piezoelectric layer 70, recesses 71 corresponding to the respective partition walls are formed. The width of the recess 71 in the first direction X is substantially the same as or wider than the width of each partition wall in the first direction. As a result, the rigidity of the portion of the vibration plate 50 that opposes the end portion of the pressure generation chamber 12 in the second direction Y, that is, the arm portion of the vibration plate 50 is suppressed, so that the piezoelectric actuator 300 can be displaced favorably. .

  The second electrode 80 is provided on the opposite side of the piezoelectric layer 70 from the first electrode 60 and constitutes a common electrode common to a plurality of active portions. Further, the second electrode 80 may or may not be provided on the inner surface of the recess 71, that is, on the side surface of the recess 71 of the piezoelectric layer 70.

  Such a piezoelectric actuator 300 composed of the first electrode 60, the piezoelectric layer 70, and the second electrode 80 is displaced by applying a voltage between the first electrode 60 and the second electrode 80. That is, by applying a voltage between both electrodes, a piezoelectric strain is generated in the piezoelectric layer 70 sandwiched between the first electrode 60 and the second electrode 80. A portion where piezoelectric distortion occurs in the piezoelectric layer 70 when a voltage is applied to both electrodes is referred to as an active portion. On the other hand, a portion where no piezoelectric distortion occurs in the piezoelectric layer 70 is referred to as an inactive portion. Further, in the active portion where piezoelectric distortion occurs in the piezoelectric layer 70, a portion facing the pressure generation chamber 12 is referred to as a flexible portion, and a portion outside the pressure generation chamber 12 is referred to as a non-flexible portion.

  In the present embodiment, all of the first electrode 60, the piezoelectric layer 70, and the second electrode 80 are continuously provided to the outside of the pressure generation chamber 12 in the second direction Y. That is, the active part is continuously provided to the outside of the pressure generation chamber 12. For this reason, a portion of the active portion facing the pressure generation chamber 12 of the piezoelectric actuator 300 is a flexible portion, and a portion outside the pressure generation chamber 12 is a non-flexible portion.

  Further, an individual wiring 91 that is a lead-out wiring is led out from the first electrode 60 of the piezoelectric actuator 300. Further, from the second electrode 80, a common wiring 92 that is a lead-out wiring is drawn out. A flexible cable 120 is connected to the individual wiring 91 and the common wiring 92. The flexible cable 120 is a flexible wiring board, and in this embodiment, a drive circuit 121 that is a semiconductor element is mounted.

  A protective substrate 30 having substantially the same size as the flow path forming substrate 10 is bonded to the surface of the flow path forming substrate 10 on the piezoelectric actuator 300 side. The protective substrate 30 has a holding portion 31 that is a space for protecting the piezoelectric actuator 300. Two holding portions 31 are formed side by side in the second direction Y between the rows of piezoelectric actuators 300 arranged in parallel in the first direction X. Further, the protective substrate 30 is provided with a through hole 32 penetrating in the third direction Z between two holding portions 31 arranged in parallel in the second direction Y. The ends of the individual wiring 91 drawn from the first electrode 60 of the piezoelectric actuator 300 and the common wiring 92 drawn from the second electrode 80 are extended so as to be exposed in the through hole 32. The flexible cable 120 is electrically connected in the through hole 32.

  On the protective substrate 30, a case member 40 that fixes the manifold 100 communicating with the plurality of pressure generating chambers 12 together with the flow path forming substrate 10 is fixed. The case member 40 has substantially the same shape as the communication plate 15 described above in a plan view, and is bonded to the protective substrate 30 and is also bonded to the communication plate 15 described above. Specifically, the case member 40 has a recess 41 having a depth in which the flow path forming substrate 10 and the protective substrate 30 are accommodated on the protective substrate 30 side. The concave portion 41 has an opening area larger than the surface of the protective substrate 30 bonded to the flow path forming substrate 10. The opening surface on the nozzle plate 20 side of the recess 41 is sealed by the communication plate 15 in a state where the flow path forming substrate 10 and the like are accommodated in the recess 41. As a result, the third manifold portion 42 is defined by the case member 40 and the flow path forming substrate 10 on the outer periphery of the flow path forming substrate 10. Then, the first manifold portion 17 and the second manifold portion 18 provided on the communication plate 15, and the third manifold portion 42 defined by the case member 40 and the flow path forming substrate 10, the manifold of this embodiment. 100 is configured. The manifold 100 is continuously provided in the first direction X, which is the direction in which the pressure generation chambers 12 are arranged, and the supply communication path 19 that communicates each pressure generation chamber 12 and the manifold 100 is the first. Are arranged side by side in the direction X.

  A compliance substrate 45 is provided on the surface of the communication plate 15 where the first manifold portion 17 and the second manifold portion 18 open. The compliance substrate 45 seals the openings of the first manifold portion 17 and the second manifold portion 18 on the liquid ejection surface 20a side. In this embodiment, the compliance substrate 45 includes a sealing film 46 made of a flexible thin film and a fixed substrate 47 made of a hard material such as metal. Since the region facing the manifold 100 of the fixed substrate 47 is an opening 48 that is completely removed in the thickness direction, one surface of the manifold 100 is sealed only with a flexible sealing film 46. The compliance portion 49 is a flexible portion.

  The case member 40 is provided with an introduction path 44 that communicates with the manifold 100 and supplies ink to each manifold 100. The case member 40 is provided with a connection port 43 through which the flexible cable 120 is inserted in communication with the through hole 32 of the protective substrate 30.

  In such a recording head 1, when ink is ejected, the ink is taken in from the introduction path 44 and the inside of the flow path is filled with ink from the manifold 100 to the nozzle 21. Thereafter, in accordance with a signal from the drive circuit 121, a voltage is applied to each piezoelectric actuator 300 corresponding to the pressure generating chamber 12, so that the diaphragm 50 is bent and deformed together with the piezoelectric actuator 300. As a result, the pressure in the pressure generating chamber 12 increases and ink droplets are ejected from the predetermined nozzle 21.

  As shown in FIG. 1, the ink jet recording apparatus 500 includes a control device 200. Here, an electrical configuration of the ink jet recording apparatus 500 of the present embodiment will be described with reference to FIG. FIG. 5 is a block diagram showing a control configuration of the ink jet recording apparatus according to the first embodiment of the present invention.

  As shown in FIG. 5, the ink jet recording apparatus 500 includes a printer controller 210 that is a control unit of the present embodiment, and a print engine 220.

  The printer controller 210 is an element that controls the entire inkjet recording apparatus 500. In the present embodiment, the printer controller 210 is provided in the control apparatus 200 provided in the inkjet recording apparatus 500.

  The printer controller 210 includes an external interface 211 (hereinafter referred to as an external I / F 211), a RAM 212 that temporarily stores various data, a ROM 213 that stores a control program, a CPU, and the like. An oscillation circuit 215 that generates a clock signal, a drive signal generation unit 216 that generates a drive signal to be supplied to the recording head 1, and dot pattern data (bitmap data) developed based on the drive signal and print data ) Etc. to the print engine 220. The internal interface 217 (hereinafter, referred to as internal I / F 217) is provided.

  The external I / F 211 receives print data including, for example, a character code, a graphic function, image data, and the like from an external device 230 such as a host computer. Further, a busy signal (BUSY) and an acknowledge signal (ACK) are output to the external device 230 through the external I / F 211.

  The RAM 212 functions as a reception buffer 212A, an intermediate buffer 212B, an output buffer 212C, and a work memory (not shown). The reception buffer 212A temporarily stores print data received by the external I / F 211, the intermediate buffer 212B stores intermediate code data converted by the control processing unit 214, and the output buffer 212C stores dot pattern data. To do. This dot pattern data is constituted by print data obtained by decoding (translating) gradation data.

  The ROM 213 stores font data, graphic functions, and the like in addition to a control program (control routine) for performing various data processing.

  The control processing unit 214 reads the print data in the reception buffer 212A and stores the intermediate code data obtained by converting the print data in the intermediate buffer 212B. Further, the intermediate code data read from the intermediate buffer 212B is analyzed, and the intermediate code data is developed into dot pattern data by referring to the font data and graphic functions stored in the ROM 213. Then, the control processing unit 214 performs the necessary decoration processing, and then stores the developed dot pattern data in the output buffer 212C.

  If dot pattern data for one line is obtained in the recording head 1, the dot pattern data for one line is output to the recording head 1 through the internal I / F 217. When dot pattern data for one line is output from the output buffer 212C, the developed intermediate code data is erased from the intermediate buffer 212B, and the development process for the next intermediate code data is performed.

  The print engine 220 includes a recording head 1, a paper feed mechanism 221, and a carriage mechanism 222. The paper feeding mechanism 221 includes a conveyance roller 8 and a motor (not shown) that drives the conveyance roller 8, and sequentially feeds the recording sheets S in conjunction with the recording operation of the recording head 1. That is, the paper feeding mechanism 221 relatively moves the recording sheet S in the first direction X. The carriage mechanism 222 includes a carriage 3 and a drive motor 6 and a timing belt 7 that move the carriage 3 in the second direction Y along the carriage shaft 5.

  The recording head 1 includes a shift register 122, a latch circuit 123, a level shifter 124, a drive circuit 121 having a switch 125, and a piezoelectric actuator 300. Further, as shown in FIG. 6, these shift register 122, latch circuit 123, level shifter 124, switch 125, and piezoelectric actuator 300 include shift register elements 122 </ b> A to 122 </ b> N provided for each nozzle 21 of the recording head 1, and latches, respectively. It consists of elements 123A to 123N, level shifter elements 124A to 124N, switch elements 125A to 125N, and piezoelectric actuators 300A to 300N. The shift register 122, latch circuit 123, level shifter 124, switch 125, and piezoelectric actuator 300 are electrically connected in this order. Is connected to.

  Note that the shift register 122, the latch circuit 123, the level shifter 124, and the switch 125 generate an applied pulse from the drive signal generated by the drive signal generation unit 216. Here, the applied pulse is actually applied to the piezoelectric actuator 300.

  Here, the drive signal including the drive waveform generated by the drive signal generation unit 216 will be described. FIG. 7 shows a drive waveform indicating a drive signal.

  As shown in FIG. 7, the drive signal COM of the present embodiment is repeatedly generated from the drive signal generation unit 216 every unit period T (ejection period T) defined by the clock signal transmitted from the oscillation circuit 215. The unit period T corresponds to one pixel such as an image to be printed on the recording sheet S. In the present embodiment, the unit period T is divided into three periods T1 to T3. The first ejection drive pulse DP1 is generated in the first period T1, the second ejection drive pulse DP2 is generated in the second period T2, and the third ejection drive pulse DP3 is generated in the third period T3. . When a dot pattern for one line (one raster) is formed in the recording area of the recording sheet S during printing, the piezoelectric actuator 300 corresponding to each nozzle 21 has the first ejection drive pulse DP1, the second Any one or more of the ejection drive pulse DP2 and the third ejection drive pulse DP3 are selectively applied. In the present embodiment, the drive signal is supplied to the first electrode 60 that is an individual electrode using the second electrode 80 that is a common electrode of the piezoelectric actuator 300 as a reference potential (Vbs). That is, the voltage applied to the first electrode 60 by the drive waveform is expressed as a potential with reference to the reference potential (Vbs).

More specifically, the first ejection pulse DP1 includes an expansion element is applied from a state where the intermediate potential Vm is applied to a first electric potential V ₁ to inflate the volume of the pressure generating chamber 12 from the reference volume P1, the expansion element an expansion maintaining element P2 maintaining the volume constant time of the pressure generating chamber 12 inflated by P1, a contraction element P3 to contract the volume of the pressure generating chamber 12 is applied from the electric potential V ₁ to the second potential V _2, contraction maintaining element P4 to maintain the volume of the pressure generating chamber 12 contracted by the contraction element P3 predetermined time, the expansion return element for returning the pressure generating chamber 12 from the second contracted state of the potential V ₂ to the reference volume of the intermediate potential Vm P5 And. When such a first ejection drive pulse DP <b> 1 is supplied to the piezoelectric actuator 300, an ink droplet corresponding to a medium dot is ejected from the nozzle 21 in the ink jet recording apparatus 500.

  The second ejection drive pulse DP <b> 2 is a drive pulse for ejecting an ink droplet corresponding to the relatively smallest dot (small dot) among the dots that can be formed in the ink jet recording apparatus 500 from the nozzle 21.

Specifically, the second ejection pulse DP2 includes an expansion element is applied from a state where the intermediate potential Vm is applied to a first electric potential V ₁ to inflate the volume of the pressure generating chamber 12 from the reference volume P11, the expansion element an expansion maintaining element P12 for maintaining the volume constant time of the pressure generating chamber 12 inflated by P11, the first contraction element P13 to contract the volume of the pressure generating chamber 12 is applied from the electric potential V ₁ to the third potential V ₃ When the volume of the first contraction and maintenance element P14, the pressure generating chamber 12 by applying a third potential V ₃ to a fourth potential V ₄ to maintain the volume of the pressure generating chamber 12 contracted by the first contraction element P13 predetermined time the the most expansion element P15 to the highest expansion, contraction and top expansion Wei element P16 maintaining the fifth potential V ₅ constant time, the volume of the fourth electric potential V ₄ from the application to the second potential V ₂ pressure generating chamber 12 First A contraction element P17, a second contraction maintaining element P18 maintaining the sixth potential V ₆ fixed time, expansion return element for returning the pressure generating chamber 12 to the reference volume of the intermediate potential Vm from the second contracted state of the potential V ₂ P19 And. The first contraction element P14 and the second contraction element P17 function as contraction elements that contract the volume of the pressure generation chamber 12 and eject ink droplets from the nozzles 21. Further, in the middle of the contraction element, that is, the most expansion element P15 is provided between the first contraction element P14 and the second contraction element P17. The most expanded element P15 is inserted while the ink droplet is ejected from the nozzle 21 by the contraction element. By providing the most expanded element P15, the ink pushed out from the nozzle 21 by the first contraction element P14. By acting so that the rear end portion of the droplet is pulled toward the pressure generation chamber 12, the ink droplet ejected from the nozzle 21 can be further reduced.

  The third ejection drive pulse DP3 has the same drive waveform as the first ejection drive pulse DP1.

  Then, by selecting one or more from the first ejection driving pulse DP1, the second ejection driving pulse DP2, and the third ejection driving pulse DP3, large, medium, and small dots are distinguished. In the present embodiment, the ink droplets corresponding to the large dots are not ejected from the nozzles 21, but the ink droplets corresponding to the two medium dots are ejected from the nozzles 21, thereby causing the large dots on the recording sheet S. Is forming. Hereinafter, ink droplets that form medium dots are referred to as medium ink droplets, and ink droplets that form small dots are referred to as small ink droplets.

  Next, control of the recording head 1 having such an electrical configuration will be described. First, a procedure for applying a drive pulse to the piezoelectric actuator 300 will be described.

  As shown in FIG. 8, first, in synchronization with the clock signal (CK) from the oscillation circuit 215, the print data (SI) constituting the dot pattern data is serially transmitted from the output buffer 212C to the shift register 122 and sequentially set. Is done. In this case, first, the most significant bit data in the print data of all the nozzles 21 is serially transmitted. When the most significant bit data serial transmission is completed, the second most significant bit data is serially transmitted. Similarly, the lower bit data is serially transmitted sequentially.

  When the print data of the bit is set in the shift register elements 122A to 122N for all the nozzles, the control processing unit 214 causes the latch circuit 123 to output a latch signal (LAT) at a predetermined timing. In response to this latch signal, the latch circuit 123 latches the print data set in the shift register 122. The latch output (LATout) which is the print data latched by the latch circuit 123 is applied to the level shifter 124 which is a voltage amplifier. When the print data is “1”, for example, the level shifter 124 boosts the print data up to a voltage value at which the switch 125 can be driven, for example, several tens of volts. The boosted print data is applied to the switch elements 125A to 125N, and the switch elements 125A to 125N are connected by the print data.

  A drive signal (COM) generated by the drive signal generation unit 216 is also applied to each of the switch elements 125A to 125N. When the switch elements 125A to 125N are connected, the switch elements 125A to 125N are connected to the switch elements 125A to 125N. A drive signal is applied to the piezoelectric actuators 300A to 300N.

  Here, as described above, the drive signal has the first ejection drive pulse DP1, the second ejection drive pulse DP2, and the third ejection drive pulse DP3 within the unit period T, and these first ejection drive pulses DP1, By selecting one or more of the second ejection driving pulse DP2 and the third ejection driving pulse DP3, large, medium and small dots are distinguished.

  In the ink jet recording apparatus 500 of this embodiment, whether or not to apply a drive signal to each piezoelectric actuator 300 can be controlled by the print data (SI), and at the same time, the size of the ejected ink droplet is selected. Can do. That is, whether or not ink is ejected from the nozzles 21 and the size of the dots can be controlled by the print data (SI). For example, in the printing cycle I, print data in which the period corresponding to the first ejection driving pulse DP1 and the third ejection driving pulse DP2 is “1” so as to apply the ejection driving signal for forming large dots. Since the switch 125 is connected by the latch signal (LAT) during the period in which the print data is “1”, the drive signal (COMout) including the first ejection drive pulse DP1 and the third ejection drive pulse DP3 is generated. The piezoelectric actuator 300 can be supplied. Then, the piezoelectric actuator 300 is displaced (deformed) by the supplied drive signal (COMout), and two medium ink droplets are ejected to form a large dot. In the printing cycle II, the print data is “0”, and the switch 125 is disconnected during the period of “0”, so that the supply of the drive signal to the piezoelectric actuator 300 is cut off. Note that, during the period in which the print data is “0”, each piezoelectric actuator 300 maintains the immediately preceding potential, so that the immediately preceding displacement state is maintained. In the printing cycle III, print data is formed such that a period corresponding to only the first ejection drive pulse DP1 is “1” so that a drive signal for forming a medium dot is applied, and from the first ejection drive pulse DP1. When the drive signal (COMout) is supplied to the piezoelectric actuator 300, medium ink droplets are ejected to form medium dots. Also, in the printing cycle IV, print data is formed so that the period corresponding to only the second ejection drive pulse DP2 is “1” so that a drive signal for forming small dots is applied, and the second ejection drive. By supplying a drive signal (COMout) composed of the pulse DP2 to the piezoelectric actuator 300, a small ink droplet is ejected to form a small dot.

  The print data (SI) for controlling whether or not ink is ejected from the nozzles 21 and the size of dots formed on the recording sheet S, that is, the size of ink droplets ejected from the nozzles 21, is recorded. The data is continuous in a unit cycle T as the head 1 moves relative to the second direction Y.

  Here, if the number of ink droplets ejected simultaneously in the nozzle row, that is, the number of so-called simultaneous shots increases, the number of piezoelectric actuators 300 that are driven simultaneously increases, and the current flowing through the drive circuit 121 and the flexible cable 120 increases. As a result, the piezoelectric actuator 300 is supplied with a drive waveform that is deteriorated compared to the drive waveform to be supplied. In particular, deterioration is likely to occur in the case of a driving waveform in which the potential difference increases and decreases rapidly in a short time, such as the second ejection driving pulse DP2.

  Here, FIG. 9 shows the second ejection drive pulse DP2 and the degraded second ejection drive pulse DP2 ′ when the number of simultaneous shots increases.

As shown in FIG. 9, when the number of simultaneous shots increases, the third potential V ₃ ′ of the first contraction element P13 and the fourth potential V ₄ ′ of the most expanded element P15 of the second ejection drive pulse DP2 ′ not reach the fourth potential _{V 4} of the third potential _{V 3} and the bottom expansion element P15 of the first contraction element P13 of the second ejection pulse DP2. When the number of simultaneous shots increases, the slope of the first contraction element P13 of the second ejection drive pulse DP2 ′, that is, the potential change rate per unit time, is the first contraction element P13 of the original second ejection drive pulse DP2. It is lower than the slope of. In addition, the gradient of the most expanded element of the second ejection drive pulse DP2 ′ is lower than the gradient of the most expanded element of the original second ejection drive pulse DP2. For this reason, when the piezoelectric actuator 300 is driven by the deteriorated second ejection drive pulse DP2 ′, the ejection characteristics of the ink droplet, the weight of the ink droplet, and the flying speed of the ink droplet are reduced.

  Here, the relationship between the number of simultaneous shots and the ink droplet flight speed Vm (m / s) is shown in FIG. As shown in FIG. 10, the ink droplet flying speed Vm decreases as the number of simultaneous shots increases. Since the recording head 1 performs printing by ejecting ink droplets while moving in the second direction Y, if the flying speed Vm of the ink droplets varies due to increase / decrease in the number of simultaneous shots, the ink droplet landing position is reached. Variations occur and print quality decreases. The same applies to the weight of each ink droplet.

  Therefore, the printer controller 210 according to the present embodiment can execute the drive waveform correction mode for correcting the drive waveform supplied to the piezoelectric actuator 300 according to the number of simultaneous shots.

  In such a drive waveform correction mode executed by the printer controller 210 of the present embodiment, the print data is divided into a plurality of regions including the number of continuous shots of two or more shots, and according to the number of simultaneous shots for each divided region. The drive waveform can be corrected. That is, instead of correcting the drive waveform for each shot, the drive waveform can be corrected for each region including the number of consecutive two or more shots. In the present embodiment, the number of simultaneous shots serving as an index for correcting the drive waveform is the second ejection drive pulse DP2, which is a drive waveform that easily deteriorates as the number of simultaneous shots increases. That is, the drive waveform is corrected according to the number of simultaneous shots of small ink droplets ejected by the second ejection drive pulse DP2.

  The print data is supplied corresponding to the same nozzle row, and as described above, a shot of ink droplets from the nozzles 21 constituting the nozzle row accompanying the relative movement of the recording head 1 with respect to the recording sheet S. And the size of ink droplets to be ejected.

  An example of such print data is shown in FIG. FIG. 11 shows print data when the recording head 1 reciprocates once in the second direction Y, that is, print data for one pass.

  As shown in FIG. 11, as described above, the print data is 3-bit data corresponding to the periods T1, T2, and T3 in the unit period T corresponding to one pixel on the recording sheet S for each nozzle. Have When the data corresponding to the print data periods T1, T2, and T3 is “0”, the drive signal is not supplied. In the periods T1, T2, and T3 when the print data is “1”, the first ejection drive pulse DP1 and the second ejection drive pulse of the drive signal COM corresponding to the periods T1, T2, and T3 that are “1”. DP2 and the third ejection drive pulse DP3 are selectively supplied. That is, the print data when forming large dots is (101), the print data when forming medium dots is (100), and the print data when forming small dots is (010). In this embodiment, the drive waveform may be corrected according to the number of simultaneous shots of small ink droplets ejected by the second ejection drive pulse.

  Here, the correction of the drive waveform according to the number of simultaneous shots is, for example, ranked into two or more according to the number of simultaneous shots, and whether or not the drive waveform is corrected and corrected for each number of simultaneous shots divided by ranking The amount can be determined. For example, in this embodiment, as shown in FIG. 10, three ranks of simultaneous shots 0 to 250 are the first rank, simultaneous shots 251 to 500 are the second rank, and simultaneous shots 501 to 800 are the third rank. It is divided into. When the number of simultaneous shots is the first rank (0 to 250), the drive waveform is not corrected. When the number of simultaneous shots is the second rank (251 to 500), the drive waveform is corrected so that the flying speed Vm becomes +1 m / s. Further, when the number of simultaneous shots is 501 to 800, the drive waveform is corrected so that the flying speed is +2 m / s. Hereinafter, the correction of the driving waveform in the second rank is referred to as correction (small), and the correction in the third rank is referred to as correction (large).

  Thereby, the flying speed Vm of the ink droplet based on the driving waveform before correction is distributed from 4.5 to 8.0 m / s, whereas the flying speed Vm of the ink droplet after correcting the driving waveform is It can be set to 7.5 ± 0.5 m / s. That is, by correcting the drive waveform, it is possible to suppress variations in the flight speed Vm.

  Such correction of the drive waveform is performed for each of the regions R1 to R3 by dividing the print data for one pass shown in FIG. 11 into three regions R1 to R3, for example. Each of the regions R1 to R3 only needs to include two or more consecutive shots. In this embodiment, the number of shots of two or more consecutive shots means the number of shots in which small ink droplets are continuously ejected by two or more shots in the same nozzle row. However, since there is also a unit cycle T in which small ink droplets are not ejected, the number of consecutive shots of two or more shots may be a number of cycles of two or more cycles in which the unit cycle T is continuous. In any case, the drive waveform is not corrected every shot or every unit period.

  Then, the printer controller 210 executes a drive waveform correction mode in which the drive waveform is corrected according to the number of simultaneous shots of the second ejection drive pulse DP2 in the nozzle row for each of the divided print data regions R1 to R3.

  In each region R1 to R3, the number of simultaneous shots may be the same or different. For example, as shown in FIG. 12, when the print data is divided into areas R1 to R3 when the recording sheet S prints an image 400 in one pass, the number of simultaneous shots with different ranks is displayed in the areas R1 and R3. It will be mixed. For this reason, when the regions R1 to R3 are ranked according to the number of simultaneous shots, the rank included in each of the regions R1 to R3 may be set to the highest rank. That is, the region R1 includes the number of simultaneous shots of the first rank and the second rank, and if the ratio of the first rank is high as a whole of the region R1, the region R1 may be defined as the first rank. .

  If each of the regions R1 to R3 is ranked by the number of simultaneous shots, when printing each region R1 to R3, the drive waveform is corrected based on the rank, and the corrected drive signal is applied to the piezoelectric actuator 300. Supply.

  That is, for example, when the number of simultaneous shots in the first area R1 is the first rank, the drive waveform is corrected based on the first rank, that is, corrected when the print data of the first area R1 is printed. Instead, the original drive waveform is supplied to the piezoelectric actuator 300.

  For example, when the number of simultaneous shots in the first region R1 is the second rank, when printing the print data in the first region R1, the drive waveform is corrected based on the second rank. Correction (small) is performed so that the flying speed Vm becomes +1 m / s, and the corrected drive waveform is supplied to the piezoelectric actuator 300.

  Further, for example, when the number of simultaneous shots in the first region R1 is the third rank, when printing the print data of the first region R1, the drive waveform is corrected based on the third rank. Correction (large) is performed so that the flying speed Vm becomes +2 m / s, and the corrected drive waveform is supplied to the piezoelectric actuator 300.

  In the print data shown in FIG. 11, the region R1 has the first rank, the region R2 has the second rank, and the region R3 has the third rank. Accordingly, in the region R1 and the region R3, the drive waveform is not corrected, and the drive waveform may be corrected (small) based on the second rank in the region R2. A specific driving waveform correction method will be described later in detail.

  Here, the drive signal correction mode will be further described with reference to FIG. FIG. 13 is a flowchart for explaining the drive signal correction method.

  First, when print data is supplied, in step S1, the printer controller 210 divides the print data into a plurality of regions, in this embodiment, three regions R1 to R3. In step S2, the printer controller 210 determines whether the number of simultaneous shots in the region R1 is the first rank. When it is determined that the number of simultaneous shots in the region R1 is the first rank (step S2: Yes), the region R1 is printed in step S3 with the default drive waveform without correcting the drive waveform.

  If it is determined in step S2 that the number of simultaneous shots in the region R1 is not the first rank (step S2: No), in step S4, the printer controller 210 determines whether the number of simultaneous shots in the region R1 is the second rank. Determine. When it is determined that the number of simultaneous shots in the region R1 is the second rank (step S4: Yes), the drive waveform is corrected (small) in step S5, and then the region R1 is printed in step S3.

  If it is determined in step S4 that the number of simultaneous shots in the region R1 is not the second rank (step S4: No), the number of simultaneous shots in the region R1 is the third rank. After correction (large), the region R1 is printed in step S3.

  Next, the same steps S7 to S11 as steps S2 to S6 of the region R1 are performed on the region R2. That is, in step S7, the printer controller 210 determines whether the number of simultaneous shots in the region R2 is the first rank. When it is determined that the number of simultaneous shots in the region R2 is the first rank (step S7: Yes), the region R2 is printed in step S8 with the default drive waveform without correcting the drive waveform.

  If it is determined in step S7 that the number of simultaneous shots in the region R2 is not the first rank (step S7: No), in step S9, the printer controller 210 determines whether the number of simultaneous shots in the region R3 is the second rank. Determine. When it is determined that the number of simultaneous shots in the region R2 is the second rank (step S9: Yes), the drive waveform is corrected (small) in step S10, and then the region R2 is printed in step S8.

  If it is determined in step S9 that the number of simultaneous shots in the region R2 is not the second rank (step S9: No), the number of simultaneous shots in the region R2 is the third rank. After correction (large), the region R2 is printed in step S8.

  Next, also about area | region R3, the same step S12-step S16 as step S2-S6 of area | region R1 are performed. That is, in step S12, the printer controller 210 determines whether the number of simultaneous shots in the region R3 is the first rank. If it is determined that the number of simultaneous shots in the region R3 is the first rank (step S12: Yes), the region R3 is printed in step S13 with the default drive waveform without correcting the drive waveform.

  If it is determined in step S12 that the number of simultaneous shots in the region R3 is not the first rank (step S12: No), in step S14, the printer controller 210 determines whether the number of simultaneous shots in the region R3 is the second rank. Determine. When it is determined that the number of simultaneous shots in the region R3 is the second rank (step S14: Yes), the drive waveform is corrected (small) in step S15, and then the region R3 is printed in step S13.

  If it is determined in step S14 that the number of simultaneous shots in the region R3 is not the second rank (step S14: No), the number of simultaneous shots in the region R3 is the third rank. After correction (large), the region R3 is printed in step S13.

  Here, a specific method of correcting the drive waveform in accordance with the number of simultaneous shots will be described with reference to FIGS. 14, 16, 18, and 20 are drive waveforms showing the correction method of the second ejection drive pulse, and FIGS. 15, 17, 19, and 21 are the corrected second ejection drive pulse. It is a drive waveform which shows deterioration of.

  The drive waveform deteriorates due to the increase in the number of simultaneous shots, and the ink ejection characteristics such as the ink droplet flying speed and the ink drop weight decrease, so the correction of increasing the voltage of the drive waveform to suppress the deterioration of the ink ejection characteristics I do.

Specifically, as shown in FIG. 14, the intermediate potential Vm, the third potential V ₃ , the fourth potential V _4, and the second potential V ₂ of the second ejection drive pulse DP2 are each an intermediate potential that is a larger potential. The second ejection drive pulse DP2A is corrected to VmA, the third potential V _3A , the fourth potential V _4A, and the second potential V _2A .

As a result, as shown in FIG. 15, even if the number of simultaneous shots is large and the second ejection drive pulse DP2A is degraded, the third of the original second ejection drive pulse DP2 to which the degraded second ejection drive pulse DP2A ′ is desired to be supplied. it can be brought closer to the potential _{V 3.} As a result, even if the piezoelectric actuator 300 is driven by the deteriorated second ejection drive pulse DP2A ′, it is possible to suppress the degradation of the ejection characteristics of the ejected small ink droplets.

  Further, assuming that the voltage change cannot be followed due to the deterioration of the drive waveform, the correction for increasing the voltage gradient may be performed.

  Specifically, as shown in FIG. 16, the inclinations of the expansion element P11, the first contraction element P13, the most expansion element P15, the second contraction element P17, and the expansion return element P19 of the second ejection drive pulse DP2, that is, The second ejection drive pulse DP2B corrected to the expansion element P11B, the first contraction element P13B, the most expansion element P15B, the second contraction element P17B, and the expansion return element P19B having a gradient larger than the potential change rate per unit time. .

  As a result, as shown in FIG. 17, even if the number of simultaneous shots is large and the second ejection drive pulse DP2B is degraded, the slope of the voltage of the degraded second ejection drive pulse DP2B ′ is the original second ejection drive to be supplied. The slope of the voltage of the pulse DP2 can be approached. As a result, even if the piezoelectric actuator 300 is driven by the deteriorated second ejection drive pulse DP2B ′, it is possible to suppress the degradation of the ejection characteristics of the ejected small ink droplets.

  Further, since the drive waveform applied to the piezoelectric actuator cannot follow the voltage change of the original drive waveform due to the deterioration of the drive waveform, the time of the contraction maintaining element is lengthened so that the voltage change can be followed.

  Specifically, as shown in FIG. 18, the second ejection drive pulse DP2C in which the time of the first contraction maintenance element P14 of the second ejection drive pulse DP2 is corrected to the first contraction maintenance element P14C, which is a longer time, To do.

As a result, as shown in FIG. 19, even if the number of simultaneous shots is large and the second ejection drive pulse DP2C deteriorates, the third of the original second ejection drive pulse DP2 to which the degraded second ejection drive pulse DP2C ′ is desired to be supplied. it can be brought closer to the potential _{V 3.} As a result, even if the piezoelectric actuator 300 is driven by the deteriorated second ejection drive pulse DP2C ′, it is possible to suppress the degradation of the ejection characteristics of the ejected small ink droplets.

  In addition, since the drive waveform applied to the piezoelectric actuator cannot follow the voltage change of the original drive waveform, correction is performed to increase the potential of the contraction element so that the voltage change can be followed.

Specifically, as shown in FIG. 20, the second ejection pulse DP2D obtained by correcting the third electric potential _{V 3} of the first contraction element P13 of the second ejection pulse DP2 to the third potential _{V 3D} is a greater potential And

As a result, as shown in FIG. 21, even if the number of simultaneous shots is large and the second ejection drive pulse DP2D deteriorates, the third of the original second ejection drive pulse DP2 to which the degraded second ejection drive pulse DP2D ′ is desired to be supplied. it can be brought closer to the potential _{V 3.} As a result, even if the piezoelectric actuator 300 is driven with the deteriorated second ejection drive pulse DP2D ′, it is possible to suppress the degradation of the ejection characteristics of the ejected small ink droplets.

  Note that these four drive waveform correction methods shown in FIGS. 14, 16, 18 and 20 may be combined in two or more.

  As described above, in this embodiment, the printer controller 210 serving as the control unit is print data supplied corresponding to the same nozzle row, and the nozzle row associated with the relative movement of the recording head 1 with respect to the recording sheet S. The print data for determining the presence or absence of shots of ink droplets from the nozzles 21 constituting each of the nozzles is divided into a plurality of regions R1 to R3 including the number of consecutive two or more shots, and the nozzles for each of the divided regions R1 to R3 The drive waveform was corrected according to the number of simultaneous shots in the row.

  Therefore, by correcting the drive waveform according to the number of simultaneous shots, it is possible to suppress variations in ink ejection characteristics due to increase / decrease in the number of simultaneous shots, and to suppress deterioration in print quality due to variations in ink ejection characteristics. Can do. Further, since the drive waveform is corrected for each of the regions R1 to R3 including the number of continuous shots of two or more print data, the time required for correcting the drive waveform is shortened and the printing time is shortened. Can do. That is, if the drive waveform is corrected for each shot, it takes time to correct the drive waveform for each shot, and the printing time becomes longer.

  In the present embodiment, the drive signal generated from one drive signal generation unit 216 can be corrected to suppress variations in ink ejection characteristics due to increase / decrease in the number of simultaneous shots. A plurality of drive signal generation units for generation are not necessary. Therefore, cost can be reduced and downsizing can be achieved.

  In the present embodiment, the print data includes data for determining the size of the ink droplet ejected from the nozzle 21. For this reason, the printer controller 210 can correct the drive waveform for ejecting small ink droplets, which are likely to deteriorate due to the increase in the number of simultaneous shots, based on the number of simultaneous shots. Therefore, it is possible to effectively suppress variation in ink ejection characteristics when ejecting small ink droplets.

  In this embodiment, the areas R1 to R3 for dividing the print data are set in advance. However, the present invention is not particularly limited to this, and the areas may be set based on the number of simultaneous shots of the print data. That is, as shown in FIG. 12, when the recording sheet S prints the image 400 in one pass, the print data is divided into regions R11, R12, and R13 for each rank of the number of simultaneous shots. And you may correct | amend the drive waveform of area | region R11-R13 according to each rank. As described above, the print quality can be further improved by dividing the region R11 to R13 for each rank of the number of simultaneous shots and correcting the drive waveform according to the rank for each region R11 to R13. That is, differences in ink discharge characteristics are unlikely to occur at the boundaries of the regions R11 to R13, the boundaries between the regions R11 and R12, and the boundaries between the regions R12 and R13. Can be made difficult to occur.

  However, when dividing into regions R11 to R13 for each rank of the number of simultaneous shots, depending on the image to be printed, the number of divisions of the region may increase compared to the case of dividing into regions R1 to R3 in advance. For this reason, dividing the areas R1 to R3 in advance can reduce the number of corrections of the drive waveform and shorten the printing time.

(Other embodiments)
As mentioned above, although one Embodiment of this invention was described, the basic composition of this invention is not limited to what was mentioned above.

  For example, in the first embodiment described above, the second ejection drive pulse DP2 is corrected according to the number of simultaneous shots of the second ejection drive pulse DP2 that easily deteriorates due to the increase in the number of simultaneous shots. Instead, the first ejection drive pulse DP1 may be corrected according to the number of simultaneous shots of the first ejection drive pulse DP1. The same applies to the third ejection drive pulse DP3. In addition, the first ejection drive pulse DP1, the second ejection drive pulse DP2, and the third ejection drive pulse according to the number of all simultaneous shots of the first ejection drive pulse DP1, the second ejection drive pulse DP2, and the third ejection drive pulse DP3. DP3 may be corrected.

  Further, for example, in the first embodiment described above, the print data for one pass is divided into the regions R1 to R3 or the regions R11 to R13, but the present invention is not particularly limited thereto. For example, the unit for dividing the print data may be one pass. That is, the print data for determining the presence or absence of a shot of ink droplets from each nozzle 21 constituting the nozzle row associated with the relative movement of the recording head 1 with respect to the recording sheet S is the paper feed of the recording sheet S in the first direction X. This includes the case where the recording head 1 is moved relative to the recording sheet S. That is, dividing the print data into a plurality of areas including the number of consecutive shots of two or more shots includes dividing the print data printed in a plurality of passes into each pass.

  In this way, the print data is divided for each pass, and the drive waveform is corrected for each pass, so that the drive waveform is corrected while the recording sheet S is fed in the first direction X. Can do. Therefore, it is not necessary to interrupt printing by correcting the drive waveform, and the printing time can be shortened.

  In the first embodiment described above, the drive signal COM includes the first discharge drive pulse DP1, the second discharge drive pulse DP2, and the third discharge drive pulse DP3 in the unit period T. However, the present invention is particularly limited to this. Instead, only the first ejection drive pulse DP1 may be repeated in the unit cycle T as the drive waveform COM according to the printing mode that defines the size of the dots, and only the second ejection drive pulse DP2 may be repeated in the unit cycle T. May be repeated. Of course, other ejection drive pulses may be included.

  Note that the printer controller 210 may execute the drive waveform correction mode in accordance with a print mode that defines the size of dots. That is, examples of the print mode that defines the dot size include a clean mode and a normal mode. For example, the clean mode is a mode in which dots formed on the recording sheet S are small and the number of simultaneous shots is large. Therefore, in the clean mode, the drive waveform correction mode is executed, the drive waveform is corrected according to the number of simultaneous shots, and the print quality is improved. In contrast, in the normal mode, the dots formed on the recording sheet S are large and the number of simultaneous shots is small. Therefore, in the normal mode, the drive waveform correction mode is not executed and the drive waveform is not corrected. Thus, in the normal mode, the printing time can be shortened by the amount that the drive waveform is not corrected compared to the clean mode.

  In addition, the ink jet recording apparatus 500 performs unidirectional printing (unidirectional printing) in which printing is performed only in one of the forward path and the backward path, and bidirectional printing (bidirectional printing) in which printing is performed in both the forward path and the backward path. Both of them may be executable. In bi-directional printing, printing is performed in both the forward path and the backward path, so that the number of ink droplet shots can be dispersed in the forward path and the backward path. On the other hand, in unidirectional printing, printing is performed only in one of the forward path and the backward path. Therefore, it is necessary to perform shots performed in both the forward path and the backward path in both directions in only one of the forward path and the backward path. There is. Therefore, the number of simultaneous shots is larger in unidirectional printing than in bidirectional printing. For this reason, the printer controller 210 may execute a drive waveform determination mode that corrects the drive waveform only in the case of unidirectional printing. That is, in bi-directional printing, the drive waveform is not corrected, and the drive waveform is corrected only in the case of unidirectional printing, thereby effectively improving the print quality of unidirectional printing in which the print quality is likely to deteriorate. .

  In the above-described first embodiment, the driving element that causes a pressure change in the pressure generation chamber 12 has been described using the thin film type piezoelectric actuator 300. However, the present invention is not particularly limited thereto, and, for example, a green sheet is pasted. For example, a thick film type piezoelectric actuator formed by a method such as the above, a longitudinal vibration type piezoelectric actuator in which piezoelectric materials and electrode forming materials are alternately stacked and expanded and contracted in the axial direction can be used. In addition, as a driving element, a heating element is arranged in the pressure generating chamber, and a droplet is discharged from the nozzle by a bubble generated by the heat generation of the heating element, or static electricity is generated between the diaphragm and the electrode, A so-called electrostatic actuator that deforms the diaphragm by electrostatic force and ejects droplets from the nozzle can be used.

  Further, in the ink jet recording apparatus 500 described above, the recording head 1 is mounted on the carriage 3 and moves in the second direction Y. However, the present invention is not particularly limited thereto. For example, the recording head 1 is fixed. Thus, the present invention can also be applied to a so-called line type recording apparatus that performs printing only by moving a recording sheet S such as paper in the first direction X. That is, the relative movement of the recording head 1 with respect to the recording sheet S is not limited to the movement of the carriage 3 in the second direction Y, but includes the conveyance of the recording sheet S in the first direction X.

  In the above-described example, the ink jet recording apparatus 500 has a configuration in which the ink cartridge 2 that is a liquid storage unit is mounted on the carriage 3, but is not particularly limited thereto, for example, a liquid storage unit such as an ink tank. May be fixed to the apparatus main body 4 and the liquid storage means and the recording head 1 may be connected via a supply pipe such as a tube. Further, the liquid storage means may not be mounted on the ink jet recording apparatus.

  Furthermore, the present invention is intended for a wide range of liquid ejecting apparatuses having a wide liquid ejecting head. For example, recording heads such as various ink jet recording heads used in image recording apparatuses such as printers, liquid crystal displays, and the like Liquid using a color material ejecting head, an organic EL display, an electrode material ejecting head used for forming an electrode such as an FED (field emission display), a bio-organic matter ejecting head used for biochip production, etc. It can also be used for an injection device.

  DESCRIPTION OF SYMBOLS 1 ... Inkjet type recording head (liquid ejecting head), 2 ... Ink cartridge, 3 ... Carriage, 4 ... Device main body, 5 ... Carriage shaft, 6 ... Drive motor, 7 ... Timing belt, 8 ... Conveyance roller, 10 ... Flow path Forming substrate, 12 ... Pressure generating chamber, 15 ... Communication plate, 16 ... Nozzle communication passage, 17 ... First manifold portion, 18 ... Second manifold portion, 19 ... Supply communication passage, 20 ... Nozzle plate, 20a ... Liquid ejection surface , 21 ... Nozzles, 21 ... All nozzles, 30 ... Protective substrate, 31 ... Holding part, 32 ... Through hole, 40 ... Case member, 41 ... Recess, 41 ... Piezoelectric actuator, 42 ... Third manifold part, 43 ... Connection port 44 ... Introduction path 45 ... Compliance substrate 46 ... Sealing film 47 ... Fixed substrate 48 ... Opening part 49 ... Compliance part 50 ... Vibration plate 51 Elastic film, 52 ... insulator film, 60 ... first electrode, 70 ... piezoelectric layer, 71 ... concave portion, 80 ... second electrode, 91 ... individual wiring, 92 ... common wiring, 100 ... manifold, 120 ... flexible cable, DESCRIPTION OF SYMBOLS 121 ... Drive circuit, 122 ... Shift register, 122A-122N ... Shift register element, 123 ... Latch circuit, 123A ... Latch element, 124 ... Level shifter, 124A-124N ... Level shifter element, 125 ... Switch, 125A-125N ... Switch element, DESCRIPTION OF SYMBOLS 200 ... Control apparatus, 210 ... Printer controller, 211 ... External interface, 212 ... RAM, 212A ... Reception buffer, 212B ... Intermediate buffer, 212C ... Output buffer, 213 ... ROM, 214 ... Control processing part, 215 ... Oscillation circuit, 216 ... Drive signal generator, 217 ... Inside 220, print engine, 221 paper feed mechanism, 222 carriage mechanism, 230 external device, 300 piezoelectric actuator, 400 image, 500 ink jet recording apparatus (liquid ejecting apparatus), COM drive signal, DP1 ... first ejection drive pulse, DP2 ... second ejection drive pulse, DP3 ... third ejection drive pulse, R1-R3 ... region

Claims (6)

A drive element that causes a pressure change with respect to the liquid in the flow path by being supplied with a nozzle row having a plurality of nozzles for ejecting liquid droplets, a flow path communicating with the nozzles, and a drive signal including a drive waveform A liquid ejecting head comprising:
A drive signal generator for generating the drive signal;
Print data supplied corresponding to the same nozzle row, wherein the print data determines whether or not there is a shot of droplets from each nozzle constituting the nozzle row as the liquid ejecting head moves relative to the medium. A drive waveform capable of correcting the drive waveform supplied to the drive element according to the number of simultaneous shots in the nozzle row for each of the divided regions. A control unit capable of executing the correction mode;
A liquid ejecting apparatus comprising:   The liquid ejecting apparatus according to claim 1, wherein the print data includes data that determines a size of a droplet discharged from the nozzle. The liquid ejecting head is provided so as to be movable in a direction orthogonal to the conveyance direction of the medium,
3. The liquid ejecting apparatus according to claim 1, wherein the divided area is divided with a reciprocal movement in the movable direction of the liquid ejecting head as one unit.   The liquid ejecting apparatus according to claim 1, wherein the control unit executes the drive waveform correction mode in accordance with a print mode that defines a size of a dot. The liquid ejecting head is provided so as to be movable in a direction orthogonal to the conveyance direction of the medium,
The liquid ejecting head includes a unidirectional printing that prints on the medium only in one of the forward path and the backward path in the movable direction, and bidirectional printing that prints on the medium in a reciprocating movable direction. Is available for printing,
The liquid ejecting apparatus according to claim 1, wherein the control unit executes the drive waveform correction mode in the unidirectional printing.   A drive element that causes a pressure change with respect to the liquid in the flow path by being supplied with a nozzle row having a plurality of nozzles for ejecting liquid droplets, a flow path communicating with the nozzles, and a drive signal including a drive waveform Print data supplied to the liquid ejecting head corresponding to the same nozzle row, and at least a shot of droplets from the nozzle accompanying relative movement of the liquid ejecting head with respect to the medium. The drive waveform to be supplied to the drive element according to the number of simultaneous shots of the drive element for each of the divided areas is divided into a plurality of areas including the number of shots of two or more shots. A drive signal correction method comprising correcting the drive signal.