JP2011115986A - Liquid ejecting apparatus and ejection timing correcting method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To shorten an adjustment time of ejection timing in each nozzle array. <P>SOLUTION: The liquid ejecting apparatus includes a head and a control part. The head is equipped with a plurality of head modules each comprised of a first nozzle array and a second nozzle array that eject liquids to a medium in one nozzle plate. The plurality of head modules are aligned in a relative moving direction to the medium. The control part controls the ejection of the liquids from the first nozzle array and the second nozzle array, and can correct the ejection timing in the first nozzle array and the ejection timing in the second nozzle array using a correction amount obtained on the basis of a pattern formed by ejecting the liquid from the first nozzle array in each of at least two head modules of the plurality of head modules. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a liquid discharge apparatus and a discharge timing correction method.

  2. Description of the Related Art Inkjet printers that form images on a medium by ejecting ink from a head that moves in a forward direction and a backward direction are used. In such a printer, the ejection timing is adjusted so that the ink landing position matches the target position.

JP 2006-306107 A

In order to match the landing position and the target landing position for all nozzle rows, ink is ejected from all nozzle rows and a pattern for each nozzle row is drawn, and the discharge timing of each nozzle row is determined based on this pattern. Adjustments are also possible. However, this method requires time for adjustment when there are many nozzle rows. Therefore, it is desirable to shorten the adjustment time of the discharge timing of the nozzle row.
The present invention has been made in view of such circumstances, and an object thereof is to shorten the adjustment time of the discharge timing of the nozzle row.

The main invention for achieving the above object is:
A head including a plurality of head modules each having a first nozzle row and a second nozzle row configured to form a single nozzle plate for discharging liquid onto a medium, wherein the plurality of head modules are arranged in a relative movement direction with respect to the medium. When,
A control unit that controls the discharge of the liquid from the first nozzle row and the second nozzle row, wherein at least two of the plurality of head modules, the liquid from the first nozzle row respectively. A control unit capable of correcting the discharge timing in the first nozzle row and the discharge timing in the second nozzle row using a correction amount obtained based on a pattern formed by discharging
It is a liquid discharge apparatus provided with.

  Other features of the present invention will become apparent from the description of the present specification and the accompanying drawings.

It is explanatory drawing which showed the external appearance structure of the printing system. 1 is a block diagram of an overall configuration of a printer according to an embodiment. FIG. 3A is a schematic diagram of the overall configuration of the printer of the present embodiment, and FIG. 3B is a cross-sectional view of the overall configuration of the printer of the present embodiment. FIG. 4A schematically shows the configuration of the linear encoder 51, and FIG. 4B schematically shows the configuration of the detection unit 566. 6 is a timing chart showing waveforms of two output signals of the detection unit 566 when the carriage motor 32 is rotating forward and when rotating reversely. 4 is a sectional view of one head module of the head 41. FIG. FIG. 4 is an explanatory diagram showing the arrangement of nozzles on the lower surface of a head 41. FIG. 8A is an explanatory diagram of a drive circuit of the head unit 40, and FIG. 8B is an explanatory diagram of a serial / parallel conversion circuit in the drive signal shaping unit 644. It is a timing chart for explanation of each signal. It is a figure explaining the landing position of the ink in bidirectional printing. FIG. 11A is an explanatory diagram of a pattern for inspecting the deviation of the ink landing position, and FIG. 11B is an explanatory diagram of the pattern after the ink ejection timing is adjusted. FIG. 12A is a diagram for explaining the relationship between the original signal before adjusting the ink ejection timing and the control signal, and FIG. 12B is a diagram for explaining the relationship between the original signal after adjusting the ink ejection timing and the control signal. is there. It is a flowchart explaining the correction procedure of the discharge timing of this embodiment. It is a figure explaining the correlation with the correction amount corresponding to a nozzle row. It is a figure explaining arrangement of a plurality of heads in a line head type printer.

  At least the following matters will become clear from the description of the present specification and the accompanying drawings.

A head including a plurality of head modules each having a first nozzle row and a second nozzle row configured to form a single nozzle plate for discharging liquid onto a medium, wherein the plurality of head modules are arranged in a relative movement direction with respect to the medium. When,
A control unit that controls the discharge of the liquid from the first nozzle row and the second nozzle row, wherein at least two of the plurality of head modules, the liquid from the first nozzle row respectively. A control unit capable of correcting the discharge timing in the first nozzle row and the discharge timing in the second nozzle row using a correction amount obtained based on a pattern formed by discharging
A liquid ejection apparatus comprising:
As described above, since the correction amount of the discharge timing of the first nozzle row can be applied as the correction amount of the discharge timing of the second nozzle row, the adjustment time of the discharge timing of the nozzle row can be shortened.

In this liquid discharge apparatus, it is preferable that the correction of the discharge timing is performed by shifting a reference discharge timing of each nozzle row for each head module.
In this way, the ejection timing can be corrected by shifting the reference ejection timing for each nozzle row.

In the at least two head modules, it is preferable that the color of the liquid ejected from the first nozzle row and the color of the liquid ejected from the second nozzle row are different from each other.
By doing in this way, the discharge timing can be adjusted also for the second nozzle row that discharges a liquid of a color different from that of the first nozzle row.

The plurality of head modules include at least three head modules, and a liquid having the same color as the medium is discharged from a nozzle row of one head module other than the at least two head modules. It is desirable that the discharge timing of the nozzle row that discharges is corrected based on the discharge timing of the first nozzle in the at least two head modules.
By doing this, it is difficult to visually recognize the pattern with the same color liquid as the medium, and even in a situation where the discharge timing cannot be corrected based on this pattern, the discharge timing of the nozzle row that discharges the same color liquid as the medium can be corrected. Can do.

The ejection timing of the nozzle row that ejects the same color liquid as the medium is the correction amount of the ejection timing of the first nozzle row in the head module other than the head module including the nozzle row that ejects the same color liquid as the medium. It is desirable to correct using the average.
By doing in this way, the discharge timing of the nozzle row which discharges the liquid of the same color as the medium can also be corrected appropriately.

The plurality of head modules include at least three head modules, and the transparent liquid is discharged from a nozzle row of one head module other than the at least two head modules, and the transparent liquid is discharged from the nozzle array. The ejection timing of the row may be corrected based on the ejection timing of the first nozzle in the at least two head modules.
By doing so, it is difficult to visually recognize the pattern with the transparent liquid, and it is possible to correct the ejection timing of the nozzle row that ejects the transparent liquid even in a situation where the ejection timing cannot be corrected based on this pattern.

Further, the discharge timing of the nozzle row that discharges the transparent liquid is obtained by using an average of correction amounts of the discharge timing of the first nozzle row in a head module other than the head module including the nozzle row that discharges the transparent liquid. It may be corrected.
By doing in this way, the discharge timing of the nozzle row which discharges a transparent liquid can also be corrected appropriately.

In a head including a plurality of head modules in which a first nozzle row and a second nozzle row for discharging liquid onto a medium are configured in one nozzle plate, the first nozzle row of at least two head modules among the plurality of head modules. Forming a pattern by discharging liquid from
Obtaining an ejection timing correction amount for each of the first nozzle rows in the at least two head modules based on the pattern;
In each of the at least two head modules, using the correction amount of the discharge timing in the first nozzle row, correcting the discharge timing in the first nozzle row and the discharge timing in the second nozzle row;
A discharge timing correction method including:
As described above, since the correction amount of the discharge timing of the first nozzle row can be applied as the correction amount of the discharge timing of the second nozzle row, the adjustment time of the discharge timing of the nozzle row can be shortened.

=== Embodiment ===
<Configuration of printing system>
An embodiment of a printing system (computer system) will be described with reference to the drawings. However, the description of the following embodiments includes embodiments relating to a computer program and a recording medium on which the computer program is recorded.

  FIG. 1 is an explanatory diagram showing an external configuration of a printing system. The printing system 100 includes a printer 1, a computer 110, a display device 120, an input device 130, and a recording / reproducing device 140. The printer 1 is a printing apparatus that prints an image on a medium such as paper, cloth, or film. The computer 110 is electrically connected to the printer 1 and outputs print data corresponding to the image to be printed to the printer 1 in order to cause the printer 1 to print an image. The display device 120 includes a display and displays a user interface such as an application program or a printer driver. The input device 130 is, for example, a keyboard 130A or a mouse 130B, and is used for operation of an application program, setting of a printer driver, and the like along a user interface displayed on the display device 120. As the recording / reproducing device 140, for example, a flexible disk drive device 140A or a CD-ROM drive device 140B is used.

  A printer driver is installed in the computer 110. The printer driver is a program for realizing a function for displaying a user interface on the display device 120 and a function for converting image data output from an application program into print data. This printer driver is recorded on a recording medium (computer-readable recording medium) such as a flexible disk FD or a CD-ROM. Alternatively, the printer driver can be downloaded to the computer 110 via the Internet. In addition, this program is comprised from the code | cord | chord for implement | achieving various functions.

<Inkjet printer configuration>
FIG. 2 is a block diagram of the overall configuration of the printer of this embodiment. FIG. 3A is a schematic diagram of the overall configuration of the printer of this embodiment. FIG. 3B is a cross-sectional view of the overall configuration of the printer of this embodiment. Hereinafter, the basic configuration of the printer of this embodiment will be described.

  The printer of this embodiment includes a transport unit 20, a carriage unit 30, a head unit 40, a detector group 50, and a controller 60. The printer 1 that has received print data from the computer 110 that is an external device controls each unit (the conveyance unit 20, the carriage unit 30, and the head unit 40) by the controller 60. The controller 60 controls each unit based on the print data received from the computer 110 and forms an image on paper. The situation in the printer 1 is monitored by the detector group 50, and the detector group 50 outputs the detection result to the controller 60. The controller 60 receiving the detection result from the detector group 50 controls each unit based on the detection result.

  The transport unit 20 is for feeding a medium (for example, the paper S) to a printable position and transporting the paper by a predetermined transport amount in a predetermined direction (hereinafter referred to as a transport direction) during printing. That is, the transport unit 20 functions as a transport mechanism that transports paper. The transport unit 20 includes a paper feed roller 21, a transport motor 22 (also referred to as a PF motor), a transport roller 23, a platen 24, and a paper discharge roller 25. However, in order for the transport unit 20 to function as a transport mechanism, all of these components are not necessarily required. The paper feed roller 21 is a roller for automatically feeding the paper inserted into the paper insertion slot into the printer. The paper feed roller 21 has a D-shaped cross section, and the length of the circumferential portion is set to be longer than the transport distance to the transport roller 23. 23 can be conveyed. The transport motor 22 is a motor for transporting paper in the transport direction, and is configured by a DC motor. The transport roller 23 is a roller that transports the paper S fed by the paper feed roller 21 to a printable region, and is driven by the transport motor 22. The platen 24 supports the paper S being printed. The paper discharge roller 25 is a roller for discharging the printed paper S to the outside of the printer. The paper discharge roller 25 rotates in synchronization with the transport roller 23.

  The carriage unit 30 is for moving (also referred to as “scanning”) the head in a predetermined direction (hereinafter referred to as a moving direction). The carriage unit 30 includes a carriage 31 and a carriage motor 32 (also referred to as a CR motor). The carriage 31 can reciprocate in the moving direction. (Thus, the head moves along the moving direction.) The carriage 31 detachably holds an ink cartridge that stores ink. The carriage motor 32 is a motor for moving the carriage 31 in the movement direction, and is constituted by a DC motor.

  The head unit 40 is for ejecting ink onto paper. The head unit 40 has a head 41. The head 41 has a plurality of nozzles that are ink discharge portions, and discharges ink intermittently from each nozzle. The head 41 is provided on the carriage 31. Therefore, when the carriage 31 moves in the movement direction, the head 41 also moves in the movement direction. Then, by intermittently ejecting ink while the head 41 is moving in the moving direction, dot lines (raster lines) along the moving direction are formed on the paper. The head unit 40 acquires data for driving the head from the control unit on the printer body side via the cable 49. The cable 49 is a flexible belt-like cable, and electrically connects the printer body and the carriage 31.

  The detector group 50 includes a linear encoder 51, a rotary encoder 52, a paper detection sensor 53, an optical sensor 54, and the like. The linear encoder 51 is for detecting the position of the carriage 31 in the moving direction. The rotary encoder 52 is for detecting the amount of rotation of the transport roller 23. The paper detection sensor 53 is for detecting the position of the leading edge of the paper to be printed. The paper detection sensor 53 is provided at a position where the front end of the paper can be detected while the paper feed roller 21 feeds the paper toward the transport roller 23. The paper detection sensor 53 is a mechanical sensor that detects the leading edge of the paper by a mechanical mechanism. More specifically, the paper detection sensor 53 has a lever that can rotate in the transport direction, and this lever is disposed so as to protrude into the paper transport path. For this reason, since the leading edge of the paper comes into contact with the lever and the lever is rotated, the paper detection sensor 53 detects the position of the leading edge of the paper by detecting the movement of the lever. The optical sensor 54 is attached to the carriage 31. The optical sensor 54 detects the presence or absence of paper by the light receiving unit detecting reflected light of the light emitted from the light emitting unit to the paper. The optical sensor 54 detects the position of the edge of the paper while being moved by the carriage 41. Since the optical sensor 54 optically detects the edge of the paper, the optical sensor 54 has higher detection accuracy than the mechanical paper detection sensor 53.

  The controller 60 is a control unit for controlling the printer. The controller 60 includes an interface unit 61, a CPU 62, a memory 63, and a unit control circuit 64. The interface unit 61 is for transmitting and receiving data between the computer 110 which is an external device and the printer 1. The CPU 62 is an arithmetic processing unit for controlling the entire printer. The memory 63 is for securing an area for storing the program of the CPU 62, a work area, and the like, and has storage means such as a RAM and an EEPROM. The CPU 62 controls each unit via the unit control circuit 64 in accordance with a program stored in the memory 63.

  FIG. 4A schematically shows the configuration of the linear encoder 51. The linear encoder 51 includes a linear encoder code plate 564 and a detection unit 566. The linear encoder code plate 564 is attached to the frame side inside the inkjet printer 1 as shown in FIG. 3A. On the other hand, the detection unit 566 is attached to the carriage 31 side. When the carriage 31 moves along the guide rail 36, the detection unit 566 moves relatively along the linear encoder code plate 564. Accordingly, the detection unit 566 detects the movement amount of the carriage 31.

<Configuration of detection unit>
FIG. 4B schematically shows the configuration of the detection unit 566. The detection unit 566 includes a light emitting diode 552, a collimator lens 554, and a detection processing unit 556. The detection processing unit 556 includes a plurality of (for example, four) photodiodes 558, a signal processing circuit 560, and, for example, two comparators 562A and 562B.

  When a voltage Vcc is applied to both ends of the light emitting diode 552 via a resistor, light is emitted from the light emitting diode 552. This light is condensed into parallel light by the collimator lens 554 and passes through the linear encoder code plate 564. The linear encoder code plate 564 is provided with slits at predetermined intervals (for example, 1/180 inch (1 inch = 2.54 cm)).

  The parallel light that has passed through the linear encoder code plate 564 enters each photodiode 558 through a fixed slit (not shown) and is converted into an electrical signal. The electric signals output from the four photodiodes 558 are subjected to signal processing in the signal processing circuit 560, the signals output from the signal processing circuit 560 are compared in the comparators 562A and 562B, and the comparison result is output as a pulse. Pulses ENC-A and ENC-B output from the comparators 562A and 562B are outputs of the linear encoder 51.

<Output signal>
5A and 5B are timing charts showing waveforms of two output signals of the detection unit 566 when the carriage motor 32 is rotating forward and when the carriage motor 32 is rotating forward. As shown in FIGS. 5A and 5B, the phase of the pulse ENC-A and the pulse ENC-B are different from each other by 90 degrees both when the carriage motor 32 is rotating forward and when it is rotating backward. When the carriage motor 32 is rotating forward, that is, when the carriage 31 is moving along the guide rail 36, the pulse ENC-A is only 90 degrees from the pulse ENC-B, as shown in FIG. 5A. When the phase advances and the carriage motor 32 reverses, the phase of the pulse ENC-A is delayed by 90 degrees from the pulse ENC-B, as shown in FIG. 5B. One cycle T of the pulse ENC-A and the pulse ENC-B is equal to the time during which the carriage 41 moves through the slit interval of the linear encoder code plate 564.

  Then, rising edges of the output pulses ENC-A and ENC-B of the linear encoder 51 are detected, the number of detected edges is counted, and the rotational position of the carriage motor 32 is calculated based on the counted value. The This count is incremented by “+1” when one edge is detected when the carriage motor 32 is rotating forward, and is “−1” when one edge is detected when rotating reversely. Is added. The period of each of the pulses ENC-A and ENC-B is equal to the time from the passage of a slit through the detection unit 566 to the passage of the next slit through the detection unit 566 of the linear encoder code plate 564. In addition, the pulse ENC-A and the pulse ENC-B are different in phase by 90 degrees. For this reason, the count value “1” of the count corresponds to ¼ of the slit interval of the linear encoder code plate 564. Thus, if the count value is multiplied by ¼ of the slit interval, the amount of movement of the carriage motor 32 from the rotational position corresponding to the count value “0” can be obtained based on the multiplication value. At this time, the resolution of the linear encoder 51 is ¼ of the slit interval of the linear encoder code plate 564.

  FIG. 6 is a cross-sectional view of one head module of the head 41. The head 41 is configured by assembling a plurality of head modules as shown in the figure.

  Here, a cross section of two nozzle rows in which a plurality of nozzles are arranged in a direction toward the paper surface of the drawing is shown. The head 41 includes a drive unit 42, a case 43 for housing the drive unit 42, and a flow path unit 44 attached to the case.

  The drive unit 42 includes a piezo element group including a plurality of piezo elements 421, a fixing plate 423 to which the piezo element group is fixed, and a flexible cable 424 for supplying power to each piezo element 421. . Each piezo element 421 is attached to the fixed plate 423 in a so-called cantilever state. The fixed plate 423 is a plate-like member having rigidity capable of receiving a reaction force from the piezo element 421. The flexible cable 424 is a flexible sheet-like wiring board, and is electrically connected to the piezo element 421 on the side surface of the fixed end opposite to the fixed plate 423. On the surface of the flexible cable 424, a head controller HC, which is a control IC for controlling the driving of the piezo element 421 and the like, is mounted. As illustrated, the head controller HC is provided for each nozzle row.

  The case 43 has a rectangular parallelepiped block-like outer shape having a storage empty portion 431 in which the drive unit 42 can be stored. The flow path unit 44 is joined to the front end surface of the case 43. The housing empty portion 431 has a size that allows the drive unit 42 to be fitted exactly. The case 43 is also formed with an ink supply pipe (not shown) for introducing ink from the ink cartridge into the flow path unit 44.

  The flow path unit 44 includes a flow path forming substrate 45, a nozzle plate 46, and an elastic plate 47. The flow path forming substrate 45 is laminated so that the flow path forming substrate 45 is sandwiched between the nozzle plate 46 and the elastic plate 47. It is configured integrally. The nozzle plate 46 is a thin plate made of stainless steel on which nozzles are formed.

  In the flow path forming substrate 45, a plurality of vacant portions serving as pressure chambers 451 and ink supply ports 452 are formed corresponding to the respective nozzles. The reservoir 453 is a liquid storage chamber for supplying the ink stored in the ink cartridge to each pressure chamber 451, and communicates with the other end of the corresponding pressure chamber 451 through the ink supply port 452. The ink from the ink cartridge is introduced into the reservoir 453 through the ink supply pipe.

  The drive unit 42 is inserted into the housing empty portion 431 with the free end portion of the piezo element 421 facing the flow path unit 44 side, and the distal end surface of the free end portion is bonded to the corresponding island portion 473. Further, the back surface of the fixing plate 423 is bonded to the inner wall surface of the case 43 that partitions the housing empty portion 431. When a drive signal is supplied to the piezo element 421 via the flexible cable 424 in this stored state, the piezo element 421 expands and contracts to expand and contract the volume of the pressure chamber 451. Due to such a change in the volume of the pressure chamber 451, pressure fluctuation occurs in the ink in the pressure chamber 451. Then, ink can be ejected from the nozzles by utilizing the fluctuation of the ink pressure.

<About nozzle>
FIG. 7 is an explanatory diagram showing the arrangement of nozzles on the lower surface of the head 41. On the lower surface of the head 41, a cyan ink nozzle row C, a magenta ink nozzle row M, a white ink nozzle row W, a clear ink nozzle row Cl, an orange ink nozzle row Or, a green ink nozzle row Gr, and a black An ink nozzle row K, a yellow ink nozzle row Y, a light magenta ink nozzle row LM, and a light cyan ink nozzle row LC are formed. White ink is ejected from the white ink nozzle row W, and this is mainly used when a white background is formed on a transparent sheet. Further, clear ink, which is transparent ink, is ejected from the clear ink nozzle row Cl, and this is mainly ink ejected to coat an image formed on the medium.

  For convenience of explanation, these nozzle rows may be referred to as A row to J row as shown in the figure. Each nozzle row includes a plurality of nozzles (180 in this embodiment) that are ejection openings for ejecting ink of each color.

  In addition, these nozzle arrays form one head module for every two nozzle arrays. Two nozzle rows in one head module share one nozzle plate. As shown in the figure, the rows A and B belong to the first head module HM1, the rows C and D belong to the second head module HM2, the rows E and F belong to the third head module HM3, The row and the H row belong to the fourth head module HM4, and the I row and the J row belong to the fifth head module HM5.

  The plurality of nozzles in each nozzle row are aligned at a constant interval (nozzle pitch: k · D) along the transport direction. Here, D is the minimum dot pitch in the carrying direction (that is, the interval at the highest resolution of dots formed on the paper S). K is an integer of 1 or more. For example, when the nozzle pitch is 180 dpi (1/180 inch) and the dot pitch in the transport direction is 720 dpi (1/720), k = 4.

  The nozzles in each nozzle row are assigned a lower number for the nozzles on the downstream side. That is, the nozzle # 1 is located downstream of the nozzle # 180 in the transport direction. Each nozzle is provided with a piezo element as a drive element for driving each nozzle to eject ink droplets.

<About driving the head>
FIG. 8A is an explanatory diagram of the drive circuit of the head unit 40. The original drive signal generator 644A is provided in the unit control circuit 64. The original drive signal generator 644 is prepared for each nozzle row. That is, in this embodiment, ten original drive signal generation units 644 are provided. The original drive signal generator 644A generates an original signal ODRV that is used in common by the nozzles # 1 to # 180. The original signal ODRV is a signal including a plurality of pulses within the main scanning period for one pixel (within the time during which the head 41 crosses the interval of one pixel).

  The drive signal shaping unit 644B is provided in the head control unit HC (FIG. 6), and is provided for each nozzle row. The drive signal shaping unit 644B receives the original signal ODRV from the original drive signal generation unit 644A and the print signal PRT as serial data. Further, control signals S1 and S2 are input to the drive signal shaping unit 644B.

  FIG. 8B is an explanatory diagram of a serial / parallel conversion circuit in the drive signal shaping unit 644. The print signal PRT is serial-parallel converted by using a circuit as shown in FIG. 8B using 360 shift registers, and converted to PRT (i) indicating ON / OFF of each nozzle. The drive signal shaping unit 644B shapes the original signal ODRV according to the level of the print signal PRT (i), and outputs it as the drive signal DRV (i) toward the piezoelectric elements of the nozzles # 1 to # 180. The piezoelectric elements of the nozzles # 1 to # 180 are driven based on the drive signal DRV from the drive signal shaping unit 644B.

<About the head drive signal>
FIG. 9 is a timing chart for explaining each signal. In other words, the timing chart of each signal of the original signal ODRV, the print signal PRT (i), and the drive signal DRV (i) is shown in FIG. Here, PRT (i) is formed from PRT.

  The original signal ODRV is a signal supplied in common to the nozzles # 1 to # 180 from the original drive signal generator 644A. In the present embodiment, the original signal ODRV includes two pulses of a first pulse W1 and a second pulse W2 within a main scanning period for one pixel (within a time during which the carriage crosses the interval of one pixel). The original signal ODRV is output from the original drive signal generation unit 644A to the drive signal shaping unit 644B.

  The print signal PRT (i) is a signal corresponding to the pixel data assigned to one pixel. That is, the print signal PRT (i) is a signal corresponding to the pixel data included in the print data. In the present embodiment, the print signal PRT (i) is a signal having 2-bit information per pixel for the nozzle #i. Note that the drive signal shaping unit 644B shapes the original signal ODRV according to the signal level of the print signal PRT (i) and outputs the drive signal DRV.

  The drive signal DRV is a signal obtained by blocking the original signal ODRV according to the level of the print signal PRT. That is, when the print signal PRT (i) is 1 level, the drive signal shaping unit 644B passes the corresponding pulse of the original signal ODRV as it is to obtain the drive signal DRV. On the other hand, when the print signal PRT is 0 level, the drive signal shaping unit 644B blocks the pulse of the original signal ODRV. The drive signal shaping unit 644B outputs the drive signal DRV to the piezo element provided for each nozzle. The piezo element is driven according to the drive signal DRV.

  The control signal S1 is input to the latch circuit and the data selector as shown in FIG. 8B. The control signal S2 is input to the data selector. The control signals S1 and S2 indicate the timing at which the print signal PRT (i) changes as shown in FIG.

  The serially transmitted print signal PRT is converted into 180 pieces of 2-bit data (parallel data) as described below. First, the print signal PRT is input to 360 shift registers. When the pulse of the control signal S1 is input to the latch circuit, 360 data of each shift register is latched. The data selector selects and outputs the data latched by the latch circuit. When the pulse of the control signal S1 is input to the latch circuit, the pulse of the control signal S1 is also input to the data selector. The data selector is in an initial state when the control signal S1 is input. The data selector in the initial state selects the data stored in the shift register W2-i before latching, and outputs it as PRT (i). Next, the data selector selects the data stored in the shift register W1-i before being latched by the pulse of the control signal S2, and outputs it as PRT (i). In this way, the serially transmitted print signal PRT is converted into 180 pieces of 2-bit data. Then, ejection / non-ejection relating to the second pulse W2 is determined by the control signal S1, and ejection / non-ejection relating to the first pulse W1 is determined by the control signal S2.

  When the print signal PRT (i) corresponds to the 2-bit data “01”, only the first pulse W1 is output in the latter half of one pixel interval. As a result, small ink droplets are ejected from the nozzles, and small dots (small dots) are formed on the paper. When the print signal PRT (i) corresponds to the 2-bit data “10”, only the second pulse W2 is output in the first half of one pixel section. As a result, medium-sized ink droplets are ejected from the nozzles, and medium-sized dots (medium dots) are formed on the paper. When the print signal PRT (i) corresponds to the 2-bit data “11”, the first pulse W1 and the second pulse W2 are output in one pixel section. Thereby, a large ink droplet is ejected from the nozzle, and a large dot (large dot) is formed on the paper. When the print signal PRT (i) corresponds to the 2-bit data “00”, neither the first pulse W1 nor the second pulse W2 is output. Thereby, in this section, ink is not ejected and dots are not formed.

  As described above, the drive signal DRV (i) in one pixel section is shaped to have four different waveforms according to four different values of the print signal PRT (i).

  FIG. 10 is a diagram for explaining ink landing positions in bidirectional printing. In the figure, the speed when ink is ejected in the forward path and the backward path is displayed as a vector. Here, the moving speed of the head 41 is Vt in both the forward path and the return path. Further, the ink ejection speed is set to V1. At this time, the ink flies in the direction of the vector indicated by DV1 in the drawing.

  Assume that the ejection timing of the printer 1 used here is still unadjusted, and as shown in the figure, the ink ejection position in the forward path is P1. On the other hand, it is assumed that the target landing position of ink is T. Then, the landing point of the ink on the paper S is separated from the target landing position T by the distance d. Therefore, if the ejection timing can be corrected so that ink is ejected earlier by the distance d, the ink landing position coincides with the target landing position T in the forward path. That is, it is only necessary to correct the ink ejection position to be P1 '. Similarly, in the case of the return path, the ink landing position can be matched with the target landing position T by changing the ink discharge position from P2 to P2 '.

  Here, a correction method has been described for a case where the landing position in the forward path and the landing position in the backward path shift when ejected from the same nozzle array. However, there is a possibility that a landing position shift between different nozzle arrays may also occur. . For example, if the landing position of the black ink in the forward path is T in the figure, the landing position of the cyan ink in the forward path will land at a position that precedes T by a distance d.

  In such a case, the target landing position of all ink colors is set as the landing position of the black ink, and in order to make it coincide with this, it is only necessary to advance the discharge timing of the cyan ink by the distance d. In other words, the landing positions can be matched by correcting whether the ejection timing is advanced or delayed in both the landing positions in the forward path and the backward path, and the landing positions in different nozzle arrays. Become.

  FIG. 11A is an explanatory diagram of a pattern for inspecting the deviation of the ink landing position. The figure shows a pattern PT1 composed of a pattern formed in the forward path and a pattern formed in the backward path. Both the pattern formed in the forward path and the pattern formed in the return path are formed so that dots are aligned in the nozzle row direction in which the nozzles are aligned. Here, for the sake of easy explanation, the pattern PT1 of only black ink will be described as an example.

  Again, ink is ejected at a predetermined ejection timing to form these patterns in the forward and backward paths of the head, but since the ejection timing is not corrected, the positions of the pattern lines in the forward path and the pattern lines in the backward path However, it is shifted by Δx in the moving direction of the head. If it is possible to grasp how much the ink landing position is deviated (in this case, Δx), the moving speed of the head is determined in advance, so by dividing the deviation amount by the moving speed (Δx / Vt) It can be determined whether the correction should be made so as to shift the time and the discharge timing.

  FIG. 11B is an explanatory diagram of the pattern after the ink ejection timing is adjusted. Here, as compared with the case of FIG. 11A, the adjustment is made so that the ink ejection timing in the backward path is advanced so that the ink landing position in the backward path is shifted to the right in the drawing by Δx. The inks ejected at are aligned so as to coincide in the moving direction of the head.

  FIG. 11C is an explanatory diagram of a pattern for inspecting the deviation of the ink landing position between different nozzle arrays. In the figure, a dot row (indicated as K) formed by ejecting ink from the black ink nozzle row in the forward path, and a dot row (indicated as C) formed by ejecting ink from the cyan ink nozzle row in the forward path. A pattern PT3 is formed.

  Here, since the ejection timing has not been adjusted, the dot row originally formed by the black ink nozzle row and the dot row formed by the cyan ink nozzle row are formed by being shifted by Δx in the head moving direction. Has been.

  Even in this case, if the landing position of the black ink is used as a reference and if it is possible to grasp how much the landing position of the cyan ink is deviated from this, the moving speed of the head is determined in advance. It can be determined whether correction should be made so as to shift the time and the discharge timing of the cyan ink.

  FIG. 11D is an explanatory diagram of a pattern after ink ejection timing is adjusted between different nozzle arrays. Here, as compared with the case of FIG. 11C, the ink ejection timing from the cyan ink nozzle row C is adjusted so that the cyan ink landing position is shifted to the right in the drawing by Δx. As a result, the dot row of black ink and the dot row of cyan ink are aligned so as to coincide with each other in the head moving direction.

  Here, the adjustment of the discharge timing of the cyan ink with respect to the black ink has been described, but the discharge timing of the inks of other colors can be performed in the same manner.

  FIG. 12A is a diagram illustrating the relationship between the original signal and the control signal before adjusting the ink ejection timing. In FIG. 12A, the original signal ODRV and the control signals S1 and S2 in the period corresponding to the main scanning period for one pixel are extracted from the timing chart in FIG. 9 described above.

  By the way, the control signals S1 and S2 are both generated based on a PTS (Pulse Timing Signal) signal. The PTS signal is a signal that defines the timing at which a pulse is generated in these control signals S1 and S2. The pulse of the PTS signal is generated based on output pulses ENC-A and ENC-B from the linear encoder 51 (detection unit 566). That is, the pulse of the PTS signal is generated according to the movement amount of the carriage 31.

  Therefore, if the generation timing of the original signal ODRV with respect to the control signals S1 and S2 can be shifted, the ejection timing can be changed with respect to the control signals S1 and S2. The timing can also be changed.

  FIG. 12B is a diagram illustrating the relationship between the original signal after adjusting the ink ejection timing and the control signal. Compared with each signal of FIG. 12A, the shape of the original signal ODRV is the same. However, the generation timing of the original signal ODRV is generated prior to the control signals S1 and S2 by Δt before that of FIG. 12A.

  As described above, when the generation timing of the original signal ODRV is shifted by Δt, the generation timing of the drive signal DRV is also advanced by Δt accordingly. Since the ink is ejected by applying the drive signal DRV to the piezo element PZT of the head 41, if the generation timing of the drive signal DRV precedes by Δt, the ink ejection timing precedes by Δt accordingly. become.

  Therefore, as a method of adjusting the ejection timing, Δt (= Δx / Vt) is stored in advance in the memory 63 of the printer as a correction amount of the ejection timing corresponding to Δx in FIG. 11A described above. The storage of the correction amount may be performed via a user interface in the printer 1 or may be input from the computer 110 via a printer driver. Then, in order to advance the ink ejection timing in the backward path direction of bidirectional printing by Δt, the generation timing of the original signal ODRV is also advanced by Δt, so that the landing positions of the forward path and the backward path can be matched as shown in FIG. 11B. it can.

  The generation timing of the original signal ODRV is changed by changing the generation timing of the original signal ODRV in the original drive signal generation unit 644A.

  Here, the discharge timing in the backward direction is advanced by Δt. However, the landing positions of the forward path and the backward path may be matched as shown in FIG. 11B by advancing the discharge timing in the forward path by Δt. Further, the landing positions of the forward path and the backward path may be matched as shown in FIG. 11B by advancing the discharge timing of the forward path and the backward path by Δt / 2.

  Although the method for advancing the ink ejection timing has been described here, if the generation timing of the original signal ODRV is delayed by Δt with respect to the control signals S1 and S2, the ink ejection timing is set. It goes without saying that it can be delayed.

  In the present embodiment, since the ejection timing of each color is adjusted for a plurality of ink colors, an original signal corresponding to each ink color is generated. Then, the generation timing for the control signals S1 and S2 may be adjusted for each original signal. For example, the drive circuit for controlling the black ink nozzle row K uses a timing control signal as shown in FIG. 12A, while the drive circuit for controlling the cyan ink nozzle row C is shown in FIG. 12B. Such a control signal whose timing is shifted by Δt is used. By doing so, the ejection timing can be corrected for each nozzle row.

  In addition, the ejection timing of the ink is adjusted by changing the generation timing of the original signal with respect to the control signals S1 and S2, but this is an example of changing the ejection timing, and the position of the pixel to be printed is changed to the pixel. It goes without saying that the ink ejection timing can be adjusted by exchanging the data so as to be shifted.

  FIG. 13 is a flowchart for explaining a discharge timing correction procedure according to the present embodiment. Here, the discharge timing correction procedure will be described with reference to this figure and the above-described figures.

  In this embodiment, one head module that discharges transparent ink and white ink (because it is difficult to see both transparent ink and white ink on white paper, these are hereinafter referred to as “head module for invisible ink” for convenience. ), The average of the correction amounts of the nozzle rows in the other head modules is applied to correct the ejection timing.

  For the head modules excluding the invisible ink head module (hereinafter referred to as “colored ink head module” for the sake of convenience), a pattern formed by one nozzle row of the two nozzle rows in each head module is used. Based on this, the ejection timings of the two nozzle rows in the same head module are corrected.

  First, a pattern for correcting the ejection timing is printed (S102). The pattern used here is the same as the pattern PT1 shown in FIG. 11A. Such a pattern PT1 is formed in the forward path and the backward path for each ink color. Specifically, ink is ejected from the A, E, G, and I nozzle rows to form the respective patterns PT1.

  Next, based on the pattern PT1 formed by discharging from the A, E, G, and I nozzle rows, a correction amount to be applied to each nozzle row is obtained (S104). The correction amount obtained here is a correction amount for the discharge timing, and is a correction amount given by how much the discharge timing is advanced or delayed. The method for obtaining this correction amount is as described above.

  Next, the correction amount for the obtained ejection timing is applied to the corresponding nozzle row (S106). The correction amount is applied by being stored in the memory 63 of the printer 1. Further, when stored in the memory 63, the correction amount is associated with the corresponding nozzle row.

  FIG. 14 is a diagram for explaining the association between the nozzle row and the corresponding correction amount. In the present embodiment, except for the second head module, the correction amount obtained based on the pattern PT1 formed by one nozzle row is also applied as the correction amount for the other nozzle row in the same head module. Specifically, the correction amount obtained based on the pattern PT1 formed by the A-row nozzle row is applied as the discharge timing correction amount for the A-row and the B-row. Further, the correction amount obtained based on the pattern PT1 formed by the nozzle row of the E row is applied as the correction amount of the ejection timing of the E row and the F row. Further, the correction amount obtained based on the pattern PT1 formed by the nozzle row of G row is applied as the correction amount of the ejection timing of G row and H row. Further, the correction amount obtained based on the pattern PT1 formed by the nozzle rows of the I row is applied as the correction amount of the ejection timing of the I row and the J row.

  As described above, assuming that the adjustment value of the discharge timing is substantially the same for each head module, the correction amount of the discharge timing of one nozzle row is applied as the correction amount of the discharge timing of the other nozzle row. This is because an error in the assembly position to the head occurs in each head module.

  When printing is performed, the landing position can be matched with the target landing position by shifting the generation timing of the corresponding original signal in each nozzle row by the correction amount stored in this way.

  Further, the reason why the pattern PT1 is not formed for the C and D columns for discharging the white ink and the clear ink is that the visibility is poor on white paper. As will be described later, the average of the correction amounts obtained based on the pattern PT1 formed with colored ink is applied to these correction amounts.

  Next, an average of the correction amounts of the nozzle rows excluding the C row and the D row is obtained (S108). Specifically, an average of correction amounts of the A column, the B column, the E column, the F column, the G column, the H column, the I column, and the J column is obtained. In the present embodiment, the A column, the B column, the E column, the F column, the G column, the H column, the I column, and the J column have the same correction amounts. It is only necessary to obtain the average of the correction amounts for the column and the I column.

  Then, the average of the obtained correction amounts is associated and stored in the memory 63 so as to be applied to the C and D columns (FIG. 14) (S110).

  In step S108, the average of the correction amounts of all the nozzle rows that discharge colored ink is obtained, but the average of the nozzle rows that sandwich the C row and the D row may be obtained. Specifically, an average of the correction amount of the B column (same as the correction amount of the A column) and the correction amount of the E column may be obtained. Then, this average may be applied to the C column and the D column.

  In step S108, the average of the light ink correction amount may be obtained. In the present embodiment, since light magenta LM and light cyan LC belong to the same head module (fifth head module), this is synonymous with applying an average of correction amounts in the I column or J column.

  In this way, the correction amount can be applied to the nozzle rows in the same head module based on the pattern PT1 formed by any one nozzle row in the same head module. Therefore, it is possible to shorten the time for obtaining the correction amount and shorten the adjustment time of the ejection timing of each nozzle row.

  Further, the clear ink belonging to the second head module and the ink of the same color as the medium have a problem that even if the pattern PT1 is formed on the medium, the visibility is insufficient and it is difficult to obtain an accurate correction amount. According to this embodiment, it is possible to appropriately correct the ejection timing of the nozzle row that ejects invisible ink by applying the average of the correction amounts of the colored inks.

  In addition, here, the ejection timing is performed to correct the ink landing positions in the forward path and the backward path of the head, but in step S102, a pattern as shown in FIG. 11C is printed, and based on the pattern by the above-described method, Landing positions between different ink colors can also be corrected appropriately.

  FIG. 15 is a diagram illustrating the arrangement of a plurality of heads in a line head type printer. In the line head 41 ′ of the line head type printer, a plurality of heads as shown in FIG. 7 are arranged. As a result, it is possible to perform printing on the entire surface of the sheet only by conveying the sheet without moving the head. In order to perform printing in this way, the paper is conveyed in a direction that intersects the direction in which the nozzles are arranged.

  Even in such a line head type printer, since the paper S moves relative to the head, for example, the target landing position of the black ink and the target landing position of the cyan ink, which should originally match, may be shifted. Can happen. However, also in this case, a pattern as shown in FIG. 11C is printed, and the ink landing position is set as the target landing position by correcting the ejection timing for each nozzle row of each head based on the pattern by the above-described method. It will be able to land on the position.

=== Other Embodiments ===
In the above-described embodiment, the printer 1 has been described as the liquid ejecting apparatus. However, the present invention is not limited to this, and other fluids other than ink (liquids, liquids in which particles of functional materials are dispersed, gels) Such a fluid can also be embodied in a liquid ejection device that ejects or ejects the fluid. For example, color filter manufacturing apparatus, dyeing apparatus, fine processing apparatus, semiconductor manufacturing apparatus, surface processing apparatus, three-dimensional modeling machine, gas vaporizer, organic EL manufacturing apparatus (especially polymer EL manufacturing apparatus), display manufacturing apparatus, film formation You may apply the technique similar to the above-mentioned embodiment to the various apparatuses which applied inkjet technology, such as an apparatus and a DNA chip manufacturing apparatus. These methods and manufacturing methods are also within the scope of application.

  The above-described embodiments are for facilitating the understanding of the present invention, and are not intended to limit the present invention. The present invention can be changed and improved without departing from the gist thereof, and it is needless to say that the present invention includes equivalents thereof.

<About the head>
In the above-described embodiment, ink is ejected using a piezoelectric element. However, the method for discharging the liquid is not limited to this. For example, other methods such as a method of generating bubbles in the nozzle by heat may be used.

1 printer,
20 transport units, 21 paper feed rollers, 22 transport motors,
23 transport roller, 24 platen, 25 discharge roller,
30 Carriage unit, 31 Carriage, 32 Carriage motor,
36 guide rails, 40 head units, 41 heads,
42 drive unit, 43 case, 44 flow path unit,
45 flow path forming substrate, 46 nozzle plate, 47 elastic plate, 49 cable,
50 detector groups, 51 linear encoders,
52 Rotary encoder, 53 Paper detection sensor, 54 Optical sensor,
60 controllers, 61 interfaces,
62 CPU, 63 memory, 64 unit control circuit,
110 computers, 120 display devices,
130 input device, 140 recording / reproducing device,
421 piezo element, 423 fixing plate, 424 flexible cable,
431 storage empty space, 451 pressure chamber, 452 ink supply port, 453 reservoir,
552 light emitting diode, 554 collimator lens, 556 detection processing unit,
558 photodiode, 560 signal processing circuit,
562A comparator, 562B comparator,
564 linear encoder code plate, 566 detector,
644A original drive signal generation unit, 644B drive signal shaping unit

Claims (8)

A head including a plurality of head modules each having a first nozzle row and a second nozzle row configured to form a single nozzle plate for discharging liquid onto a medium, wherein the plurality of head modules are arranged in a relative movement direction with respect to the medium. When,
A control unit that controls the discharge of the liquid from the first nozzle row and the second nozzle row, wherein at least two of the plurality of head modules, the liquid from the first nozzle row respectively. A control unit capable of correcting the discharge timing in the first nozzle row and the discharge timing in the second nozzle row using a correction amount obtained based on a pattern formed by discharging
A liquid ejection apparatus comprising:   The liquid ejection apparatus according to claim 1, wherein the ejection timing correction is performed by shifting a reference ejection timing of each nozzle row for each head module.   3. The liquid ejection apparatus according to claim 1, wherein, in each of the at least two head modules, a color of the liquid ejected from the first nozzle row and a color of the liquid ejected from the second nozzle row are different from each other. . The plurality of head modules includes at least three head modules;
From the nozzle row of one head module other than the at least two head modules, a liquid having the same color as the medium is discharged,
4. The liquid ejection according to claim 1, wherein ejection timing of a nozzle row that ejects liquid of the same color as the medium is corrected based on ejection timing of the first nozzle in the at least two head modules. apparatus.   The discharge timing of the nozzle row that discharges the same color liquid as the medium is the average of the correction amount of the discharge timing of the first nozzle row in the head module other than the head module including the nozzle row that discharges the same color liquid as the medium. The liquid ejection device according to claim 4, wherein the liquid ejection device is corrected by using the liquid ejection device. The plurality of head modules includes at least three head modules;
The transparent liquid is discharged from the nozzle row of one head module other than the at least two head modules,
4. The liquid ejection apparatus according to claim 1, wherein ejection timing of the nozzle row that ejects the transparent liquid is corrected based on ejection timing of the first nozzle in the at least two head modules. 5.   The ejection timing of the nozzle row that ejects the transparent liquid is corrected using an average of the correction amount of the ejection timing of the first nozzle row in a head module other than the head module that includes the nozzle row that ejects the transparent liquid. The liquid ejection device according to claim 6. In a head including a plurality of head modules in which a first nozzle row and a second nozzle row for discharging liquid onto a medium are configured in one nozzle plate, the first nozzle row of at least two head modules among the plurality of head modules. Forming a pattern by discharging liquid from
Obtaining an ejection timing correction amount for each of the first nozzle rows in the at least two head modules based on the pattern;
In each of the at least two head modules, using the correction amount of the discharge timing in the first nozzle row, correcting the discharge timing in the first nozzle row and the discharge timing in the second nozzle row;
A discharge timing correction method including:

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