JP2011161718A - Recorder and control method - Google Patents

Abstract

A recording apparatus capable of accurately detecting a positional deviation of printing is provided.
The recording apparatus forms a first dot group during a forward movement and forms a second dot group and a third dot group during a backward movement. The first dot group, the second dot group, A detection pattern 100 constituted by the third dot group 103 is formed. Next, the detection pattern 100 is detected by the two-dimensional sensor 30, and image information of the detection pattern 100 is acquired. Next, the image information of the detection pattern 100 is analyzed, and the two-dimensional frequency characteristic of the detection pattern 100 is acquired. Next, based on the two-dimensional frequency characteristics, a positional deviation of dots printed when the carriage 5 reciprocates is detected.
[Selection] Figure 4

Description

  The present invention relates to a recording apparatus such as an ink jet printer.

  An ink jet recording apparatus ejects ink from a recording head during reciprocation in the main scanning direction, attaches ink onto the recording medium, and prints an image (dot) on the recording medium. Then, the recording medium is conveyed in the sub-scanning direction using a conveyance roller or the like, and recording in the main scanning direction is repeated to form an image on the recording medium.

  However, if an image (dot) is printed on the recording medium during the reciprocating movement in the main scanning direction, the image (dot) recorded during the forward movement is deviated from the image (dot) recorded during the backward movement ( Print misalignment is likely to occur.

  For this reason, conventionally, the ink ejection timing during the forward movement and the backward movement is adjusted to eliminate the above-described misregistration of printing. The adjustment of the ink ejection timing is performed using a predetermined adjustment pattern.

  For example, as a technical document filed prior to the present invention, in Patent Document 1 (Japanese Patent Laid-Open No. 2004-358759), the return path pattern is superimposed on the forward path pattern with reference to the forward path pattern. The forward path pattern is a reference adjustment pattern formed during the forward movement, and the backward path pattern is an adjustment pattern for adjustment formed during the backward movement. Next, the superimposed adjustment pattern is detected, and the user determines the optimum adjustment pattern by visual observation from the change in density and color of the detected adjustment pattern, and uses the determined adjustment pattern. It is decided to adjust the misalignment of printing.

  However, the determination by visual inspection cannot accurately detect the positional deviation of printing because the determination method of the adjustment pattern for adjustment differs for each user.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a recording apparatus and a control method capable of accurately detecting a positional deviation of printing.

  In order to achieve this object, the present invention has the following features.

<Recording device>
The recording apparatus according to the present invention includes:
A recording head provided with a nozzle array in which a plurality of nozzles for ejecting ink are arranged in the conveyance direction of the recording medium;
A carriage on which the recording head is mounted;
Moving means for reciprocating the carriage in a direction orthogonal to the conveyance direction of the recording medium;
Conveying means for conveying the recording medium;
Discharge control means for discharging ink from the nozzles at an arbitrary timing during reciprocation of the carriage, printing dots on the recording medium with the ink, and forming a detection pattern;
A two-dimensional sensor that detects the detection pattern formed on the recording medium and acquires image information of the detection pattern;
Analyzing the image information of the detection pattern acquired by the two-dimensional sensor, and acquiring the two-dimensional frequency characteristics of the detection pattern;
Detecting means for detecting a positional deviation of printing of dots printed when the carriage is reciprocated based on the two-dimensional frequency characteristic acquired by the analyzing means;
The discharge control means includes
During the forward movement of the carriage, ink is ejected a plurality of times at regular intervals in a direction orthogonal to the transport direction using nozzles upstream of the transport direction among the nozzles of the nozzle row, and the plurality of times First dot group forming means for forming a first dot group on the recording medium with the ink of
After the recording medium is transported by a predetermined amount by the transporting means, when the carriage moves backward, the first nozzle group is used to move the first dot group downstream from the nozzles forming the first dot group by using a predetermined amount of the first dot group. A second ink is formed by ejecting ink a plurality of times at a timing when dots are printed at the center positions of two adjacent points among the dots constituting the dot group, and forming a second dot group on the recording medium by the plurality of times of ink. Dot group forming means;
When the carriage moves backward, the first dot group is configured in a direction perpendicular to the transport direction by using a nozzle located at a predetermined distance from the nozzle forming the second dot group in the transport direction. A third dot that ejects ink a plurality of times at the timing when the dot and the dots constituting the second dot group are printed, and forms a third dot group on the recording medium by the plurality of times of ink. Group forming means,
The detection pattern including the first dot group, the second dot group, and the third dot group is formed.

<Control method>
The control method according to the present invention includes:
A recording head provided with a nozzle array in which a plurality of nozzles for ejecting ink are arranged in the conveyance direction of the recording medium;
A carriage on which the recording head is mounted;
Moving means for reciprocating the carriage in a direction orthogonal to the conveyance direction of the recording medium;
Conveying means for conveying the recording medium;
Discharge control means for discharging ink from the nozzles at an arbitrary timing during reciprocation of the carriage, printing dots on the recording medium with the ink, and forming a detection pattern;
A two-dimensional sensor that detects the detection pattern formed on the recording medium and acquires image information of the detection pattern;
Analyzing the image information of the detection pattern, and obtaining the two-dimensional frequency characteristics of the detection pattern;
Detecting means for detecting a positional deviation of printing of dots printed when the carriage is reciprocated based on the two-dimensional frequency characteristics, and a control method performed by a recording apparatus comprising:
The discharge control means includes
During the forward movement of the carriage, ink is ejected a plurality of times at regular intervals in a direction orthogonal to the transport direction using nozzles upstream of the transport direction among the nozzles of the nozzle row, and the plurality of times A first dot group forming step for forming a first dot group on the recording medium with the ink of
After the recording medium is transported by a predetermined amount by the transporting means, when the carriage moves backward, the first nozzle group is used to move the first dot group downstream from the nozzles forming the first dot group by using a predetermined amount of the first dot group. A second ink is formed by ejecting ink a plurality of times at a timing when dots are printed at the center positions of two adjacent points among the dots constituting the dot group, and forming a second dot group on the recording medium by the plurality of times of ink. A dot group forming step;
When the carriage moves backward, the first dot group is configured in a direction perpendicular to the transport direction by using a nozzle located at a predetermined distance from the nozzle forming the second dot group in the transport direction. A third dot that ejects ink a plurality of times at the timing when the dot and the dots constituting the second dot group are printed, and forms a third dot group on the recording medium by the plurality of times of ink. And a group formation process,
The detection pattern including the first dot group, the second dot group, and the third dot group is formed.

  According to the present invention, it is possible to accurately detect a positional deviation of printing.

FIG. 2 is a diagram illustrating a schematic configuration example of a mechanism unit of a recording apparatus according to an embodiment. It is a figure which shows the example of schematic structure of the printing mechanism and detection mechanism of the recording device of this embodiment. It is a figure which shows the structural example of the control mechanism of the recording device of this embodiment. 3 is a diagram illustrating a configuration example of a detection pattern 100. FIG. 5 is a first diagram for explaining an example of a method for forming a detection pattern 100. FIG. 5 is a second diagram for explaining an example of a method for forming a detection pattern 100. FIG. FIG. 5 is a diagram for explaining a detection pattern 100 having a printing position shift in a main scanning direction and a sub-scanning direction. FIG. 5 is a diagram for explaining a detection pattern 100 in which there is no positional deviation of printing in the main scanning direction and the sub-scanning direction. It is a figure for demonstrating the reference frequency (H1) of the main scanning direction. FIG. 5 is a diagram for explaining a detection pattern 100 having a printing position shift in the main scanning direction. It is a figure for demonstrating the frequency component (A1, B1) of the main scanning direction at the time of position shift generation | occurrence | production. It is a figure for demonstrating the frequency component of the main scanning direction at the time of position shift generation | occurrence | production. FIG. 5 is a diagram for explaining a detection pattern 100 having a printing position shift in the sub-scanning direction. It is a figure for demonstrating the reference frequency (H2) of a subscanning direction. It is a figure for demonstrating the frequency component (B2) of the subscanning direction at the time of position shift generation | occurrence | production. FIG. 5 is a diagram for explaining a detection pattern 100 having a printing position shift in a main scanning direction and a sub-scanning direction. It is a figure for demonstrating the frequency component (A1, B1, B2) of the main scanning direction at the time of position shift generation | occurrence | production, and a subscanning direction. 5 is a diagram for explaining an example of forming a detection pattern 100. FIG. It is a figure which shows the processing operation example of the recording device of this embodiment. It is a 1st figure for demonstrating 3rd Embodiment, and is a figure for demonstrating the detection pattern 100 of a state without an assembly | attachment error in the main scanning direction. FIG. 10 is a second diagram for explaining the third embodiment, and is a diagram for explaining a detection pattern 100 in a state where there is an assembly error in the main scanning direction. It is a 1st figure for demonstrating 4th Embodiment, and is a figure for demonstrating the detection pattern 100 of a state without an assembly | attachment error in a subscanning direction. It is a 2nd figure for demonstrating 4th Embodiment, and is a figure for demonstrating the detection pattern 100 of a state with an assembly | attachment error in a subscanning direction.

(Outline of the recording apparatus of the present embodiment)
First, the outline of the recording apparatus of the present embodiment will be described with reference to FIGS. 2, 3, and 4.

  The recording apparatus in the present embodiment includes a recording head 6 provided with a nozzle row 61 in which a plurality of nozzles that eject ink are arranged in the conveyance direction of the recording medium 16, a carriage 5 on which the recording head 6 is mounted, and a carriage 5 Moving means (corresponding to the control unit 107 and main scanning driver 109) and reciprocating movement in the direction orthogonal to the conveying direction of the recording medium 16 (main scanning direction) and conveying means for conveying the recording medium 16 (control unit 107, sub-scanning) (Equivalent to the scanning driver 113 and the paper transport unit 112), and the ink is ejected from the nozzles at any timing during the reciprocating movement of the carriage 5, and the ink is printed on the recording medium 16 to form the detection pattern 100. Control means (corresponding to the control unit 107 and the recording head driver 111), a two-dimensional sensor 30 that detects the detection pattern 100 formed on the recording medium 16, and acquires image information of the detection pattern 100, and the detection pattern 100 Image information Analysis means (corresponding to the control unit 107) for analyzing the information and acquiring the two-dimensional frequency characteristics of the detection pattern 100, and based on the two-dimensional frequency characteristics, the positional deviation of the printing of the dots printed when the carriage 5 is reciprocated. Detecting means (corresponding to the control unit 107) for detecting.

  The ejection control means (107, 111) uses a nozzle upstream of the transport direction among the nozzles of the nozzle row 61 during the forward movement of the carriage 5, and is constant in a direction (main scanning direction) perpendicular to the transport direction. A first dot group forming unit that ejects ink a plurality of times at intervals and forms the first dot group 101 on the recording medium 16 by a plurality of times of ink, and a predetermined amount of the recording medium 16 is conveyed by a conveying unit (107, 113, 112). Then, when the carriage 5 moves backward, two adjacent dots among the dots constituting the first dot group 101 are used by using a nozzle that is a predetermined amount downstream from the nozzle that formed the first dot group 101 in the transport direction. Second dot group forming means for ejecting ink a plurality of times at the timing when dots are printed at the center position of the dots, and forming the second dot group 102 on the recording medium 16 by the plurality of times of ink, and return movement of the carriage 5 Sometimes the second dock The dots and the second dots constituting the first dot group 101 in the direction (main scanning direction) perpendicular to the transport direction using the nozzles located at a predetermined distance from the nozzles forming the second group 102 in the transport direction A third dot group forming means for discharging ink a plurality of times at the timing when dots are printed at the same positions as the dots constituting the group 102, and forming the third dot group 103 on the recording medium 16 by the plurality of times of ink; And a detection pattern 100 composed of a first dot group 101, a second dot group 102, and a third dot group 103 is formed.

  As a result, the recording apparatus of the present embodiment can accurately detect a printing misalignment. Hereinafter, the recording apparatus of the present embodiment will be described in detail with reference to the accompanying drawings.

(First embodiment)
<Example of schematic configuration of mechanism of recording apparatus>
First, a schematic configuration example of a mechanism unit of the recording apparatus according to the present embodiment will be described with reference to FIG.

  In the recording apparatus of the present embodiment, the main support guide rod 3 and the sub support guide rod 4 are horizontally mounted between the side plates 1 and 2 on both sides in a substantially horizontal positional relationship, and the main support guide rod 3 and the sub support guide rod 4 The carriage 5 is configured to be slidably supported in the main scanning direction.

  The carriage 5 has four recording heads 6 that discharge yellow (Y) ink, magenta (M) ink, cyan (C) ink, and black (Bk) ink, with their discharge surfaces (nozzle surfaces) facing downward. It is installed. The carriage 5 has four ink cartridges 7 (symbol “7” is one of the ink cartridges) above the recording head 6 (symbol “6” means any of the recording heads or a generic name). (Or generic name) is interchangeably mounted. The ink cartridge 7 is an ink supply body for each color for supplying ink to the four recording heads 6. The carriage 5 is connected to a timing belt 11 stretched between a driving pulley (drive timing pulley) 9 and a driven pulley (idler pulley) 10 that are rotated by the main scanning motor 8, and drives and controls the main scanning motor 8. By doing so, it is configured to move in the main scanning direction. The movement in the main scanning direction is controlled based on an encoder value obtained by providing an encoder sensor 41 on the carriage 5 and detecting the mark on the encoder sheet 40 by the encoder sensor 41.

  Further, the recording apparatus of the present embodiment is configured such that the subframes 13 and 14 are erected on the bottom plate 12 that connects the side plates 1 and 2, and the transport roller 15 is rotatably held between the subframes 13 and 14. ing. A sub-scanning motor 17 is disposed on the sub-frame 14 side, and in order to transmit the rotation of the sub-scanning motor 17 to the conveying roller 15, a gear 18 fixed to the rotation shaft of the sub-scanning motor 17 and the conveying roller 15 And a gear 19 fixed to the shaft.

  Further, between the side plate 1 and the subframe 12, a reliability maintaining and recovering mechanism (hereinafter referred to as “subsystem”) 21 of the recording head 6 is disposed. The sub-system 21 is configured by holding four cap means 22 for capping the ejection surface of the recording head 6 by a holder 23 and holding the holder 23 by a link member 24 so as to be swingable. Then, when the carriage 5 moves in the main scanning direction and the carriage 5 comes into contact with the engaging portion 25 provided in the holder 23, the holder 23 lifts up, and the cap means 22 caps the ejection surface of the recording head 6. Like to do. Further, when the carriage 5 moves to the print area side, the holder 23 is lifted down so that the cap means 22 is separated from the ejection surface of the recording head 6.

  The cap means 22 is connected to the suction pump 27 via the suction tube 26, forms an atmosphere opening port, and communicates with the atmosphere via the atmosphere opening tube and the atmosphere opening valve. The suction pump 27 discharges the sucked waste liquid (waste ink) to a waste liquid storage tank.

  A wiper blade 30 for wiping the discharge surface of the recording head 6 is attached to the blade arm 31 at the side of the holder 23. The blade arm 31 is pivotally supported and rotated by a driving means (not shown). The cam is swung by the rotation of the cam.

<Configuration example of printing mechanism and detection mechanism of recording apparatus>
Next, a configuration example of the printing mechanism and the detection mechanism of the recording apparatus of the present embodiment will be described with reference to FIG.

  As shown in FIG. 2, the printing mechanism of the recording apparatus of this embodiment includes a carriage 5 and a main support guide rod 3. The carriage 5 includes a recording head 6.

  The printing mechanism of the present embodiment conveys the recording medium 16 in the sub-scanning direction while moving and scanning the carriage 5 on which the recording head 6 shown in FIG. 2 is mounted in the main scanning direction, and the recording head 6 according to a predetermined printing timing signal. Ink is ejected from the nozzle row 61 mounted on the recording medium 16 to the recording medium 16, and an image (dot) is printed on the recording medium 16 to form an image.

  In the printing mechanism of the present embodiment, the recording medium 16 conveyed just below the recording head 6 by the rotation of the conveying roller 15 is conveyed, and image formation is performed by ink ejection. Note that the conveyance amount of the recording medium 16 is controlled by position information of the A, B, and Z phases of an encoder (not shown) attached on the rotation shaft of the conveyance roller 15 (not shown). In the present embodiment, the reference position of the transport roller 15 is aligned by the Z phase, and a positional deviation detection operation described later is started.

  As shown in FIG. 2, the detection mechanism of this embodiment includes a two-dimensional sensor guide rod 200 and a two-dimensional sensor 30. The detection mechanism of the present embodiment is located on the downstream side of the recording head 6 (the conveyance direction side of the recording medium 16). The two-dimensional sensor guide lot 200 supports the two-dimensional sensor 30.

  The two-dimensional sensor 30 detects a detection pattern 100 formed on the recording medium 16 by a printing mechanism, and acquires image information of the detection pattern 100. The detection mechanism of the present embodiment detects the detection pattern 100 formed on the recording medium 16 with the two-dimensional sensor 30, and a control unit (not shown) acquires image information of the detection pattern 100.

  The configuration of the two-dimensional sensor 30 and the detection method thereof are not particularly limited as long as the detection pattern 100 formed on the recording medium 16 can be detected, and any known configuration or known detection method may be used. Applicable. Similarly, the arrangement position of the two-dimensional sensor 30 is not particularly limited as long as it can detect the detection pattern 100 formed on the recording medium 16, and can be arranged at an arbitrary position. is there. For example, the two-dimensional sensor 30 can be configured to be integrated with the recording head 6 and disposed on the carriage 5.

<Configuration example of control mechanism of recording apparatus>
Next, a configuration example of the control mechanism of the recording apparatus of the present embodiment will be described with reference to FIG.

  The control mechanism of the recording apparatus according to the present embodiment includes a control unit 107, a main storage unit 118, a sub storage unit 119, a carriage 5, a main scanning driver 109, a recording head 6, a recording head driver 111, a two-dimensional sensor 30, and a paper transport unit. 112, a sub-scan driver 113, an image processing unit 120, and an adjustment pattern generation unit 121.

  The control unit 107 supplies recording data and a drive control signal (pulse signal) to the main storage unit 118 and each driver, and controls the entire recording apparatus. The control unit 107 controls driving of the carriage 5 in the main scanning direction via the main scanning driver 109. Further, the ink ejection timing by the recording head 6 is controlled via the recording head driver 111. Further, the driving of the paper conveyance unit 112 (conveyance belt or the like) in the sub scanning direction is controlled via the sub scanning driver 113.

  The two-dimensional sensor 30 detects the detection pattern 100 formed on the recording medium 16, and outputs image information of the detection pattern 100 to the control unit 107.

  The main storage unit 118 stores necessary information. For example, a program such as a processing procedure executed by the control unit 107 is stored. The main storage unit 118 can be rewritten from the outside. The secondary storage unit 119 is used as a working memory or the like.

  The control unit 107 according to the present embodiment reads image information from the image processing unit 120 according to the print mode, and converts the read image information into an image format for the recording head in the sub storage unit 119. Then, the image information converted in the secondary storage unit 119 is transferred to the recording head driver 111. The recording head driver 111 generates various timing signals for driving the head in accordance with the printing mode, and transfers the various timing signals for driving the head and image information to the recording head 6 to perform printing processing.

  Further, the control unit 107 controls driving of the carriage 5 in the main scanning direction via the main scanning driver 109 according to the print mode, and controls the paper conveying unit 112 (conveying belt or the like) via the sub scanning driver 113. Controls driving in the sub-scanning direction to perform printing operation.

  In addition, when performing the positional deviation detection operation, the control unit 107 transmits a parameter for generating the detection pattern 100 to the adjustment pattern generation unit 121, and the adjustment pattern generation unit 121 uses the detection pattern 100 based on the parameter. Is generated. The control unit 107 converts the detection pattern 100 generated by the adjustment pattern generation unit 121 into an image format for the recording head in the sub storage unit 119 in the same manner as during normal printing. Then, the main scanning driver 109, the carriage 5, the recording head driver 111, the recording head 6, the sub-scanning driver 113, the paper transport unit 112, and the like are controlled in the same manner as in normal printing, and the detection pattern 100 is formed on the recording medium 16. After forming the detection pattern 100, the control unit 107 detects the detection pattern 100 with the two-dimensional sensor 30, and detects the detection pattern 100 and obtains image information of the detection pattern 100 as the sub storage unit 119. Are stored in sequence. The control unit 107 performs two-dimensional frequency analysis such as two-dimensional Fourier transform on the image information of the detection pattern 100 stored in the sub storage unit 119, and acquires frequency characteristics in the main scanning direction and the sub scanning direction. The control unit 107 performs printing in the main scanning direction and the sub-scanning direction from the difference between the acquired frequency characteristics in the main scanning direction and the sub-scanning direction and a predetermined reference frequency characteristic in the main scanning direction and the sub-scanning direction. Detect misalignment.

<Configuration example of detection pattern 100>
Next, a configuration example of the detection pattern 100 will be described with reference to FIG.

  As shown in FIG. 4, the detection pattern 100 includes a first dot group 101, a second dot group 102, and a third dot group 103. In the present embodiment, the dot group means a group composed of a plurality of dots.

  The first dot group 101 is composed of a plurality of dots that are printed on the recording medium 16 when the carriage 5 moves in the forward direction, and is used to detect a positional deviation in printing in the main scanning direction and the sub-scanning direction.

  The second dot group 102 is composed of a plurality of dots that are printed on the recording medium 16 when the carriage 5 moves backward after the recording medium 16 on which the first dot group 101 is formed is conveyed by a distance corresponding to one recording medium conveyance. Used to detect misalignment of printing in the main scanning direction.

  The third dot group 103 is composed of a plurality of dots that are printed at the same time when the dots constituting the second dot group 102 are printed on the recording medium 16 (at the time of the backward movement). Used to detect.

  Before forming the detection pattern 100 on the recording medium 16, the control unit 107 inputs parameters necessary for forming the detection pattern 100 to the adjustment pattern generation unit 121 in advance. The control unit 107 changes the parameters input to the adjustment pattern generation unit 121 to change the print position of each dot constituting the detection pattern 100, the dot interval in the main scanning direction, the dot interval in the sub-scanning direction, the number of dot printings, etc. Can be changed.

  For example, the dot interval in the main scanning direction between the dots constituting the first dot group 101 and the dots constituting the second dot group 102, the dots constituting the second dot group 102, and the third dot group 103 The dot interval in the sub-scanning direction with respect to the dots constituting the is arbitrarily determined according to the resolution of the two-dimensional sensor 30, the type of the recording medium 16 on which the detection pattern 100 is formed, and the like.

  The recording apparatus of the present embodiment detects the detection pattern 100 configured by the first dot group 101, the second dot group 102, and the third dot group 103 shown in FIG. To get. Then, the obtained image information of the detection pattern 100 is subjected to a two-dimensional frequency analysis, and based on the analysis result, a printing misalignment in the main scanning direction and the sub scanning direction is detected.

<Example of forming detection pattern 100>
Next, an example of a method for forming the detection pattern 100 will be described.

  First, using the Z phase of an encoder (not shown) attached to the transport roller 15, the reference position of the transport roller 15 is adjusted to determine the roller reference position (initial position). The roller reference position (initial position) is a start position for forming the detection pattern 100 on the recording medium 16.

  When the roller reference position (initial position) is determined, while moving and scanning the carriage 5 in the forward direction, among the nozzles of the nozzle row 61, the nozzles on the upstream side with respect to the transport direction (nozzles on the nozzle upstream side) The dots constituting the first dot group 101 are printed on the recording medium 16 at predetermined intervals, and the first dot group 101 shown in FIG.

  Next, the recording medium 16 is conveyed by a distance corresponding to one conveyance of the recording medium from the roller reference position (initial position). The distance for the recording medium 1 conveyance unit is ideally equal to or less than the length of the nozzle row 61 in the sub-scanning direction. As a result, even when the recording medium 16 is transported by one ideal transport unit, the sub-scanning position of the recording medium 16 on which the first dot group 101 is formed is the transport direction in the nozzles of the nozzle row 61. On the other hand, the dots constituting the second dot group 102 can be printed using the nozzles on the downstream side (nozzles on the nozzle downstream side).

  After the recording medium 16 is transported by a distance corresponding to one transport unit, the dots constituting the second dot group 102 are recorded at a predetermined timing using the nozzles on the downstream side of the nozzle while moving and scanning the carriage 5 in the backward direction. Printing is performed on the medium 16, and the second dot group 102 shown in FIG. 6 is formed on the recording medium 16. The nozzle used when forming the second dot group 102 is ideally a nozzle located at the position of the first dot group 101 formed on the recording medium 16 after conveyance, as shown in FIG.

  The predetermined timing for printing the dots constituting the second dot group 102 on the recording medium 16 is ideally the dot constituting the second dot group 102 is printed between the dots constituting the first dot group 101. It will be the timing. That is, when there is no print position deviation in the main scanning direction, an ideal second dot group 102 as shown in FIG. 6 can be formed on the recording medium 16.

  Further, using the nozzle separated from the nozzle forming the second dot group 102 by a prescribed pixel (sub-scanning printing prescribed width) in the sub-scanning direction, dots constituting the third dot group 103 are recorded at a predetermined timing on the recording medium 16. The third dot group 103 shown in FIG. 6 is formed on the recording medium 16.

  The predetermined timing for printing the dots constituting the third dot group 103 is ideally set so that the main scanning position is the same as the dots constituting the first dot group 101 and the dots constituting the second dot group 102. This is the timing at which the dots constituting the 3-dot group 103 are printed. That is, when there is no print position deviation in the main scanning direction and the sub-scanning direction, an ideal third dot group 103 as shown in FIG. 6 can be formed on the recording medium 16.

  Note that the first dot group 101 ′ shown on the upstream side of the nozzle shown in FIG. 6 is used when the second dot group 102 and the third dot group 103 are formed on the recording medium 16 using the nozzle on the downstream side of the nozzle. The dots constituting the first dot group 101 ′ are printed on the recording medium 16 at predetermined intervals using the upstream nozzle. Further, the second dot group 102 ′ and the third dot group 103 ′ (not shown) that constitute the detection pattern 100 together with the first dot group 101 ′ shown in FIG. 6 are the first dots shown in FIG. After the recording medium 16 in which the group 101 ′ is formed is conveyed by a distance corresponding to one conveyance unit, the recording medium 16 is formed using a nozzle on the downstream side of the nozzle.

  As described above, the recording apparatus of the present embodiment forms the first dot group 101 shown in FIG. 5 during the forward movement, and forms the second dot group 102 and the third dot group 103 shown in FIG. 6 during the backward movement. Thus, the detection pattern 100 composed of the first dot group 101, the second dot group 102, and the third dot group 103 is formed on the recording medium 16.

<Analysis method of detection pattern 100>
Next, a method for analyzing the detection pattern 100 will be described.

  The recording apparatus of the present embodiment detects the detection pattern 100 formed on the recording medium 16 with the two-dimensional sensor 30, and acquires image information of the detection pattern 100. Then, two-dimensional frequency analysis such as two-dimensional Fourier transform is performed on the image information of the detection pattern 100, and the frequency characteristic in the main scanning direction (frequency characteristic in the direction orthogonal to the transport direction) and the frequency characteristic in the sub-scanning direction ( Frequency characteristic in the transport direction) is acquired. The main scanning direction and sub-scanning are calculated from the difference between the acquired frequency characteristics in the main scanning direction and frequency characteristics in the sub-scanning direction, and the predetermined reference frequency characteristics in the main scanning direction and reference frequency characteristics in the sub-scanning direction. The positional deviation of the direction printing is detected.

  When there is no misalignment in printing in the main scanning direction, as shown in FIG. 6, the dots constituting the first dot group 101 and the dots constituting the second dot group 102 are equally spaced in the main scanning direction. It is printed on the recording medium 16.

  If there is no positional deviation in printing in the sub-scanning direction, the dots constituting the first dot group 101 and the dots constituting the third dot group 103 are defined in the sub-scanning direction as shown in FIG. The pixels (sub-scanning printing specified width) are separated and printed on the recording medium 16.

  However, when there is a misalignment in printing in the main scanning direction, as shown in FIG. 7, the dots constituting the first dot group 101 printed during the forward movement and the second dot group 102 printed during the backward movement are constituted. The information obtained from the first dot group 101, the second dot group 102, and the third dot group 103 constituting the detection pattern 100 is not the same interval as the dots to be printed. Deviation components (main scanning printing deviation components B1, A1) are included.

  Further, when there is a positional deviation in printing in the sub-scanning direction, as shown in FIG. 7, the dots constituting the first dot group 101 printed before the medium conveyance and the third dot group printed after the medium conveyance are performed. The first dot group 101, the second dot group 102, and the third dot group that constitute the detection pattern 100, instead of an ideal distance in which the interval between the dots constituting the 103 is separated by a prescribed pixel (sub-scanning printing prescribed width). The information obtained from 103 includes a positional deviation component of printing in the sub-scanning direction (eccentric error component; transport shift amount due to eccentricity).

  In this embodiment, for the sake of simplification of description, a case will be described in which a positional deviation of printing occurs in units of one pixel in both the main scanning direction and the sub-scanning direction. However, by adjusting the accuracy of the two-dimensional sensor 30 and the dots constituting the detection pattern 100, it is possible to detect a print position shift of one pixel or less or a print position shift due to an eccentric error of the transport roller 15.

  FIG. 8B is obtained by detecting the detection pattern 100 in the ideal state with no printing positional deviation in the main scanning direction and the sub-scanning direction shown in FIG. An example in which the image information of the detection pattern 100 is subjected to two-dimensional frequency analysis and position information of each dot constituting the detection pattern 100 is acquired is shown. In the present embodiment, the position information shown in FIG. 8B is referred to as a frequency component.

  In the present embodiment, the prescribed interval between dots in the main scanning direction constituting the detection pattern 100 (dot interval in the main scanning direction shown in FIG. 4) is known in advance, and thus can be obtained from between the dots that are not less than the prescribed interval. Frequency components can be filtered out.

  In addition, since the prescribed interval between the dots in the sub-scanning direction constituting the detection pattern 100 (dot interval in the sub-scanning direction shown in FIG. 4) is also known in advance, the frequency component obtained from the dots exceeding the prescribed interval is filtered. Can be removed.

  Furthermore, the frequency component to be analyzed is only the first quadrant. As a result, as shown in FIG. 8B, the pixel interval of the detection pattern 100 in the main scanning direction appears on the X axis, and the pixel interval of the detection pattern 100 in the sub scanning direction appears on the Y axis. It will be.

  In the recording apparatus of this embodiment, if the printing process is performed according to the optimum print timing signal during the reciprocating movement in the main scanning direction, the first dot group 101 and the second dot group 102 printed during the reciprocating movement are shown in FIG. As shown in (a), printing is performed at regular intervals (h1) in the main scanning direction. When the first dot group 101 and the second dot group 102 shown in FIG. 8A are detected by the two-dimensional sensor 30 and the image information obtained by the detection is two-dimensional frequency analyzed, as shown in FIG. A reference frequency characteristic in the main scanning direction is obtained.

  As in the first dot group 101 and the second dot group 102 shown in FIG. 8A, when the dots constituting the second dot group 102 exist at the center position between the dots constituting the first dot group 101, The dots constituting the first dot group 101 and the dots constituting the second dot group 102 do not overlap and are arranged at a constant interval with a width of h1. As shown in FIG. 8A, the reference frequency (H1) in the main scanning direction is such that the dots constituting the second dot group 102 exist at the center position between the dots constituting the first dot 101 group. This is a frequency component obtained when the dot interval between the dots constituting the first dot group 101 and the dots constituting the second dot group 102 is h1. Since the third dot group 103 is configured by printing with a dot interval h1, the third dot group 103 is detected by the two-dimensional sensor 30, and the image information obtained by the detection is analyzed by two-dimensional frequency analysis. As shown in FIG. 9, the reference frequency characteristic in the main scanning direction is obtained.

  FIG. 10B shows a detection pattern 100 when the two-dimensional sensor 30 detects the detection pattern 100 when the printing position deviation occurs in the main scanning direction shown in FIG. An example when the image information is subjected to two-dimensional frequency analysis and the position information of each dot constituting the detection pattern 100 is acquired is shown. FIG. 10A shows a configuration example of the detection pattern 100 when a print position shift occurs in the main scanning direction, and FIG. 10B shows position information obtained from the detection pattern 100 of FIG. (Frequency component).

  The frequency component on the X axis shown in FIG. 10B is a frequency component (ideal frequency component) obtained from a specified interval (ideal interval) between dots in the main scanning direction constituting the detection pattern 100. It can be seen that different frequency components exist. That is, it can be seen that there is a frequency component different from the frequency component from which the reference frequency in the main scanning direction is obtained. For this reason, it can be seen that there is a positional deviation of printing in the main scanning direction.

  Further, the frequency component on the Y axis shown in FIG. 10B is a frequency component (frequency component in an ideal state) obtained from a specified interval (ideal interval) between dots in the sub-scanning direction constituting the detection pattern 100. It can be seen that there exists only. That is, it can be seen that there are only frequency components from which the reference frequency in the sub-scanning direction can be obtained. For this reason, it can be seen that there is no positional deviation of printing in the sub-scanning direction.

  As shown in FIG. 10 (a), a printing position shift occurs in the main scanning direction due to the printing position shift in the main scanning direction of the dots constituting the second dot group 102 printed during the backward movement. In this case, the dots constituting the first dot group 101 and the dots constituting the second dot group 102 printed during the reciprocating movement are not printed at regular intervals in the main scanning direction, as shown in FIG. The dots constituting the first dot group 101 printed during the forward movement and the dots constituting the second dot group 102 printed during the backward movement are printed in a biased manner toward and away from each other. For this reason, the dot interval between the dots constituting the first dot group 101 and the dots constituting the second dot group 102 is not a constant interval, but two dot intervals (b1, a1) appear. When the first dot group 101 and the second dot group 102 shown in FIG. 10A are detected by the two-dimensional sensor 30 and the image information obtained by the detection is two-dimensional frequency analyzed, as shown in FIG. Thus, two frequency components (A1, B1) different from the reference frequency (H1) in the main scanning direction are obtained. Therefore, the frequency components (A1, B1) in the main scanning direction and the reference frequency (H1) in the main scanning direction are compared, and the difference is calculated. Based on the difference, printing in the main scanning direction is performed. A positional shift can be detected.

  For example, when there is no print position misalignment in the main scanning direction, the reference frequency (H1) in the main scan direction is acquired and the difference becomes 0. Therefore, there is a print position misalignment in the main scanning direction. It can be detected that there is not. Also, if there is a print misalignment in the main scan direction, the frequency components (A1, B1) in the main scan direction are acquired and the difference is obtained, so a print misalignment in the main scan direction occurs. Can be detected.

  As shown in FIG. 6, the recording apparatus of the present embodiment prints the dots constituting the second dot group 102 at the center position of the printing interval of the dots constituting the first dot group 101 in the main scanning direction. The dots constituting the first dot group 101 and the dots constituting the second dot group 102 are prevented from overlapping in the main scanning direction. For this reason, frequency analysis in the main scanning direction can be facilitated.

  For example, as shown in FIG. 12A, when the dots constituting the first dot group 101 and the dots constituting the second dot group 102 overlap in the main scanning direction, the first dot group 101, the first dot group 101, The image information obtained from the 2-dot group 102 has a waveform with a constant period (frequency H) as shown in FIG. 12A, and the output value of the two-dimensional frequency analysis result is a reference as shown in FIG. The output value of frequency H increases.

  In addition, as shown in FIG. 12B, when the dots constituting the first dot group 101 and the dots constituting the second dot group 102 are shifted by half a dot in the main scanning direction, a line ( The phenomenon that the pattern) becomes fat occurs. For this reason, the image information obtained from the first dot group 101 and the second dot group 102 has a wide waveform width as shown in FIG. When image information having a wide waveform width is subjected to frequency analysis, for example, the reference frequency is calculated based on the median value of the image information or the edge (start position, etc.) of the image information. As a result, the period of the waveform becomes the same (frequency H) as that of the first dot group 101 and the second dot group 102 shown in FIG. As a result, the output value of the reference frequency H becomes higher as shown in FIG.

  When the detection pattern 100 is formed by superimposing the dots constituting the first dot group 101 and the dots constituting the second dot group 102, when a positional deviation of printing of less than one dot occurs, FIG. As shown in b), the lines of the first dot group 101 and the second dot group 102 are thickened. However, even if the lines of the first dot group 101 and the second dot group 102 are thick, the periods themselves of the first dot group 101 and the second dot group 102 do not change. This is the same (frequency H) as in the first dot group 101 and the second dot group 102 shown in a). For this reason, when the detection pattern 100 is formed by superimposing the dots constituting the first dot group 101 and the dots constituting the second dot group 102, it may not be possible to accurately detect the positional deviation of printing. is there.

  For this reason, in the present embodiment, as shown in FIG. 6, the dots constituting the second dot group 102 are printed at the center position of the printing interval of the dots constituting the first dot group 101 in the main scanning direction. The dots constituting the dot group 101 and the dots constituting the second dot group 102 are prevented from overlapping in the main scanning direction. For this reason, the phenomenon that the lines of the first dot group 101 and the second dot group 102 become thick does not occur. As a result, the above-described problem does not occur, and the printing position shift can be detected easily and accurately.

  FIG. 13B shows the detection pattern 100 obtained by detecting the detection pattern 100 when the printing position deviation occurs in the sub-scanning direction shown in FIG. An example when the image information is subjected to two-dimensional frequency analysis and the position information of each dot constituting the detection pattern 100 is acquired is shown. FIG. 13A shows a configuration example of the detection pattern 100 when a print position shift occurs in the sub-scanning direction, and FIG. 13B shows position information obtained from the detection pattern 100 of FIG. (Frequency component).

  In the frequency component on the X axis shown in FIG. 13B, only the frequency component (ideal frequency component) obtained from the specified interval (ideal interval) between the dots in the main scanning direction constituting the detection pattern 100 is included. You can see that it exists. That is, it can be seen that there are only frequency components from which the reference frequency in the main scanning direction can be obtained. For this reason, it can be seen that there is no positional deviation of printing in the main scanning direction.

  However, the frequency component on the Y-axis shown in FIG. 13B includes a frequency component (ideal frequency component) obtained from a specified interval (ideal interval) between dots in the sub-scanning direction constituting the detection pattern 100. It can be seen that there are different frequency components. That is, it can be seen that there is a frequency component different from the frequency component from which the reference frequency in the sub-scanning direction is obtained. For this reason, it can be seen that there is a positional deviation of printing in the sub-scanning direction.

  In the sub-scanning direction, when there is no eccentric error of the conveying roller 15 and there is no positional deviation in printing in the sub-scanning direction, dots are printed at regular intervals in the sub-scanning direction as shown in FIG. Is printed. When the first dot group 101 and the third dot group 103 shown in FIG. 8A are detected by the two-dimensional sensor 30, and the image information obtained by the detection is two-dimensional frequency analyzed, as shown in FIG. A reference frequency characteristic in the sub-scanning direction can be obtained.

  When dots are printed at regular intervals in the sub-scanning direction as in the first dot group 101, the second dot group 102, and the third dot group 103 shown in FIG. 8A, the printed dots overlap. Without being arranged at a constant interval with a width of h2. The reference frequency (H2) in the sub-scanning direction is a frequency obtained when the interval between dots printed in the sub-scanning direction is h2, as shown in FIG. 8 (a). Further, since the second dot group 102 and the third dot group 103 are printed with the sub-scanning printing prescribed width h2, the second dot group 102 and the third dot group 103 are detected by the two-dimensional sensor 30, When two-dimensional frequency analysis is performed on the image information obtained by the detection, a reference frequency characteristic in the sub-scanning direction is obtained as shown in FIG.

  If there is an eccentricity error of the transport roller 15 and there is a positional deviation in printing in the sub-scanning direction, the dots constituting the first dot group 101, the second dot group 102, and the third dot group 103 are As shown in FIG. 13A, the distance b2 between the dots constituting the first dot group 101 and the third dot group 103 and the second dot group 102 and the third dot are not printed at regular intervals in the sub-scanning direction. The distance h2 of dots constituting the group 103 is printed differently. For this reason, the interval between dots printed in the sub-scanning direction is not a constant interval, but two intervals (b2, h2) appear. When the first dot group 101, the second dot group 102, and the third dot group 103 shown in FIG. 13 (a) are detected by the two-dimensional sensor 30, and the image information obtained by the detection is subjected to two-dimensional frequency analysis, As shown in FIG. 15, a frequency component (B2) different from the reference frequency characteristic (H2) in the sub-scanning direction is obtained. Therefore, by comparing the frequency component (B2) in the sub-scanning direction with the reference frequency (H2) in the sub-scanning direction and calculating the difference, it is possible to detect a printing misalignment in the sub-scanning direction. . For example, when there is no printing position misalignment in the sub-scanning direction, the reference frequency (H2) in the sub-scanning direction is acquired and the difference becomes 0. Therefore, there is a printing misalignment in the sub-scanning direction. It can be detected that there is not. In addition, when the print position deviation occurs in the sub-scanning direction, the frequency component (B2) in the sub-scanning direction is acquired, and the difference is obtained. Therefore, the print position deviation occurs in the sub-scanning direction. It can be detected.

  FIG. 16B is obtained by detecting the detection pattern 100 when the print position deviation occurs in the main scanning direction and the sub-scanning direction shown in FIG. An example in which the image information of the detection pattern 100 is subjected to two-dimensional frequency analysis and position information of each dot constituting the detection pattern 100 is acquired is shown. FIG. 16A shows a configuration example of the detection pattern 100 when a printing position shift occurs in the main scanning direction and the sub-scanning direction, and FIG. 16B shows the detection pattern 100 in FIG. The position information (frequency component) obtained is shown.

  The frequency component on the X axis shown in FIG. 16B is the frequency component (ideal frequency component) obtained from the specified interval (ideal interval) between the dots in the main scanning direction constituting the detection pattern 100. It can be seen that different frequency components exist. That is, it can be seen that there is a frequency component different from the frequency component from which the reference frequency in the main scanning direction is obtained. For this reason, it can be seen that there is a positional deviation of printing in the main scanning direction.

  In addition, the frequency component on the Y axis shown in FIG. 16B includes a frequency component (frequency component in an ideal state) obtained from a specified interval (ideal interval) between dots in the sub-scanning direction constituting the detection pattern 100. It can be seen that there are different frequency components. That is, it can be seen that there is a frequency component different from the frequency component from which the reference frequency in the sub-scanning direction is obtained. For this reason, it can be seen that there is a positional deviation of printing in the sub-scanning direction.

  When the printing position shift occurs simultaneously in the main scanning direction and the sub scanning direction, as shown in FIG. 16A, dots are not printed at regular intervals in the main scanning direction and the sub scanning direction, and the detection pattern 100 is changed. The first dot group 101, the second dot group 102, and the third dot group 103 that are configured are printed with a bias toward and away from the sub-scanning direction and the main scanning direction, respectively. When the detection pattern 100 shown in FIG. 16 (a) is detected by the two-dimensional sensor 30, and the image information obtained by the detection is two-dimensional frequency analyzed, as shown in FIG. 17, in the main scanning direction and the sub-scanning direction. On the other hand, frequency components different from the reference frequency characteristics appear, and a total of three frequency components (A1, B1, B2) are obtained. Therefore, by comparing the frequency components (A1, B1, B2) in the main scanning direction and the sub-scanning direction with the reference frequencies (H1, H2) in the main scanning direction and the sub-scanning direction, and calculating the difference, It is possible to detect a positional deviation of printing in the main scanning direction and the sub scanning direction.

  In addition, the positional deviation adjustment of the printing in the main scanning direction is made up of two frequency components (A1, B1) in the main scanning direction acquired at the time of the positional deviation and a reference frequency (H1) in the main scanning direction set in advance. If the difference is obtained and the print timing signal at the time of return pass printing is adjusted based on the difference, the positional deviation of printing in the main scanning direction can be adjusted.

  That is, the difference between the main scanning direction frequency components (A1, B1) obtained from the first dot group 101 and the second dot group 102 and a predetermined reference frequency component (H1) in the main scanning direction is obtained. If the print timing signal at the time of backward printing is adjusted based on the difference, it is possible to adjust the positional deviation of printing in the main scanning direction.

  Further, since the same frequency component as the reference frequency component (H1) is obtained from the third dot group 103, it can be compared with the frequency component (H1) obtained from the third dot group 103. Since the frequency component obtained from the third dot group 103 is the largest component when a deviation occurs, the frequency component can be specified.

  Therefore, the main scanning direction frequency component (A1, B1) obtained from the first dot group 101 and the second dot group 102 and the main scanning direction frequency component (H1) obtained from the third dot group 103 are If the difference is obtained and the print timing signal at the time of return pass printing is adjusted based on the difference, the positional deviation of printing in the main scanning direction can be adjusted.

  Also, the positional deviation adjustment of the printing in the sub-scanning direction is to obtain the difference between the frequency component (B2) in the sub-scanning direction acquired when the positional deviation occurs and the predetermined reference frequency (H2) in the sub-scanning direction, If the transport distance by the transport roller 15 is adjusted based on the difference, it is possible to adjust the positional deviation of printing in the sub-scanning direction.

  That is, the difference between the frequency component (B2) in the sub-scanning direction obtained from the first dot group 101 and the third dot group 103 and the predetermined reference frequency component (H2) in the sub-scanning direction is obtained, and the difference is obtained. Based on the above, if the transport amount by the transport roller 15 is adjusted, the positional deviation of printing in the sub-scanning direction can be adjusted.

  Further, since the same frequency component as the reference frequency component (H2) is obtained from the second dot group 102 and the third dot group 103, the frequency component (H2) obtained from the second dot group 102 and the third dot group 103 is obtained. ). Since the frequency component obtained from the second dot group 102 and the third dot group 103 is the largest component when a deviation occurs, the frequency component can be specified.

  For this reason, the frequency component (B2) in the sub-scanning direction obtained from the first dot group 101 and the third dot group 103 and the frequency component (H2) in the sub-scanning direction obtained from the second dot group 102 and the third dot group 103 are obtained. ) And the amount of conveyance by the conveyance roller 15 is adjusted based on the difference, and the positional deviation of printing in the sub-scanning direction can be adjusted.

  As described above, the recording apparatus according to the present embodiment forms the detection pattern 100 including the first dot group 101, the second dot group 102, and the third dot group 103 on the recording medium 16. Then, the detection pattern 100 formed on the recording medium 16 is detected by the two-dimensional sensor 30, and the image information of the detection pattern 100 is acquired. The image information of the acquired detection pattern 100 is subjected to two-dimensional frequency analysis. The position information of each dot that constitutes is acquired. As a result, the positional deviation of the printing in the main scanning direction and the positional deviation of the printing in the sub scanning direction are simultaneously detected, and the positional deviation of the printing in the main scanning direction and the positional deviation of the printing in the sub scanning direction are adjusted. can do.

  In order to obtain correction data for each conveyance unit for one rotation of the conveyance roller 15, as shown in FIG. 18, the number of conveyance times required for one rotation of the conveyance roller 15 (n = 1 to N). ), The detection pattern 100 is formed on the recording medium 16, and the detection pattern 100 for each conveyance is detected by the two-dimensional sensor 30, and the positional deviation of the printing in the main scanning direction and the positional deviation of the printing in the sub scanning direction , Need to be detected. Note that n represents the number of times of conveyance of the conveyance roller 15, and N represents the number of conveyance of the conveyance roller 15 when the conveyance roller 15 is rotated once (n = N).

  As a result, the ideal transport amount in the sub-scanning direction and the actual transport amount in each transport unit are acquired as print position shift components in the sub-scanning direction, and the eccentricity data for one rotation of the transport roller 15 is obtained. Can be acquired.

  In addition, since the misregistration component for printing in the main scanning direction can be acquired multiple times, the accuracy of the misregistration component for printing in the main scanning direction can be obtained by averaging the misregistration components for printing in the main scanning direction that have been acquired multiple times. Can be improved.

  The recording apparatus of the present embodiment stores the acquired positional deviation component of printing in the main scanning direction and the positional deviation component of printing in the sub-scanning direction in the secondary storage unit 119, and stores them in the secondary storage unit 119. Based on the positional deviation component, the positional deviation of printing in the main scanning direction and the sub-scanning direction is adjusted.

  Specifically, for the main scanning direction, frequency components (A1, B1) in the main scanning direction obtained from the first dot group 101 and the second dot group 102, and a predetermined reference frequency in the main scanning direction. A difference between the component (H1) and the component is calculated, and a correction value for adjusting the print timing signal at the time of backward printing is calculated. Then, based on the correction value, the print timing signal at the time of return pass printing is corrected, and the corrected print timing signal at the time of return pass printing is stored in the sub storage unit 119. Then, using the print timing signal at the time of return pass printing after correction stored in the sub storage unit 119, the positional deviation of printing in the main scanning direction is adjusted. The difference between the main scanning direction frequency component (A1, B1) obtained from the first dot group 101 and the second dot group 102 and the main scanning direction frequency component (H1) obtained from the third dot group 103. It is also possible to calculate a correction value for adjusting the print timing signal at the time of return pass printing.

  For the sub-scanning direction, a frequency component (B2) in the sub-scanning direction obtained from the first dot group 101 and the third dot group 103, and a predetermined reference frequency component (H2) in the sub-scanning direction , And the positional deviation amount of printing in each conveyance unit in the sub-scanning direction is calculated. Then, based on the amount of positional deviation of printing in each transport unit, a correction value for each transport unit is calculated, and the transport amount of the transport unit of the transport roller 15 set in the previous printing operation is calculated as described above. Reflecting the calculated correction value of each transport unit, the transport amount after the eccentricity correction is calculated, and the transport amount after the eccentricity correction is stored in the sub storage unit 119 as the corrected transport amount used in each transport unit. . Then, using the corrected carry amount stored in the sub storage unit 119, the positional deviation of printing in the sub scanning direction is adjusted. The frequency component (B2) in the sub-scanning direction obtained from the first dot group 101 and the third dot group 103 and the frequency component (H2) in the sub-scanning direction obtained from the second dot group 102 and the third dot group 103. It is also possible to calculate the positional deviation amount of printing in each conveyance unit in the sub-scanning direction.

<Processing operation example of recording apparatus>
Next, an example of processing operation of the recording apparatus of the present embodiment will be described with reference to FIG. FIG. 19 is a diagram illustrating a processing operation example for detecting a positional deviation of printing.

  First, the reference position of the transport roller 15 is adjusted (step S1).

  Next, the detection pattern 100 is formed on the recording medium 16 (step S2).

  Next, the detection pattern 100 formed on the recording medium 16 is detected using the two-dimensional sensor 30, and image information of the detection pattern 100 is acquired (step S3).

  Next, two-dimensional frequency analysis is performed on the acquired image information of the detection pattern 100, and position information (frequency component) of each dot constituting the detection pattern 100 is acquired (step S4).

  Next, filter processing in the main scanning direction and sub-scanning direction is performed, and the print position shift component in the main scan direction (X-axis direction) and the print position shift component in the sub-scan direction (Y-axis direction) are separated. (Step S5).

  Next, based on the positional deviation component of the printing in the main scanning direction, the positional deviation detection of the printing in the main scanning direction is performed (step S6), and a correction value for adjusting the printing timing signal during the backward printing is calculated ( Step S7).

  The correction value is the difference between the frequency component (A1, B1) in the main scanning direction obtained from the first dot group 101 and the second dot group 102 and the predetermined reference frequency component (H1) in the main scanning direction. Then, a correction value for adjusting the print timing signal at the time of return pass printing is calculated.

  Next, an average value of a plurality of correction values calculated so far in step S7 is calculated (step S8). The average value can be calculated by dividing the α correction value calculated so far in step S7 by the number α. Α indicates the number of correction values calculated each time the transport roller 15 is transported after the reference position of the transport roller in step S1, and α = n. However, n becomes n = 1 when the detection pattern 100 is formed for the first time after the reference position of the transport roller is aligned. In step S12 described later, “A detection pattern of the number of times of transport for one rotation has been detected? ”Is a number that is incremented by +1 each time it becomes“ No ”(n = n + 1) (that is, a number that is incremented by +1 for each conveyance roller conveyance). When n = N (N indicates the number of times the conveyance roller 15 is conveyed when the conveyance roller 15 is rotated once), the detection pattern of the number of conveyance times for one rotation is detected in step S12 described later. did? Becomes “Yes”.

  Further, based on the positional deviation component of the printing in the sub scanning direction, the positional deviation detection of the printing in the sub scanning direction is performed (step S9), and the positional deviation amount of the nth printing in the sub scanning direction is calculated (step S10). .

  The positional deviation amount is obtained by calculating the difference between the frequency component (B2) in the sub-scanning direction obtained from the first dot group 101 and the third dot group 103 and the reference frequency component (H2) in the sub-scanning direction determined in advance. Then, the positional deviation amount of printing in each transport unit in the sub-scanning direction is calculated.

  Next, based on the positional deviation amount calculated in step S10, the conveyance amount after the eccentric correction of the nth conveyance is calculated (step S11).

  Next, it is determined whether or not the detection pattern 100 for the number of conveyances for one rotation is detected (step S12), and the above-described processing is repeated until the detection pattern 100 for the number of conveyances for one rotation is detected.

  Then, when the detection pattern 100 for the number of times of conveyance for one rotation is detected (step S12 / Yes), the processing is ended (End).

  Regarding the formation of the first dot group 101, the second dot group 102, and the third dot group 103, in the main scanning direction, dots are continuously printed within a range that falls within the detection area of the two-dimensional sensor 30. Is possible. In addition, if it is less than the carry amount in the sub-scanning direction, it is possible to print dots within a range that falls within the detection area of the two-dimensional sensor 30. Thereby, since many dots can be printed and handled as image information, it is possible to improve the detection accuracy of the printing misalignment.

<Operation / Effect of Recording Apparatus of this Embodiment>
As described above, the printing apparatus according to the present embodiment forms the first dot group 101 when the carriage 5 moves in the forward path. Next, after the recording medium 16 on which the first dot group 101 is formed is conveyed by a predetermined amount, the second dot is formed at the timing when the dots are formed at the center positions of two adjacent dots among the dots constituting the first dot group 101. Group 102 is formed. Further, the third dot group 103 is formed at the same timing as the dots forming the first dot group 101 and the dots forming the second dot group 102 in the main scanning direction, and the first dot group is formed. A detection pattern 100 composed of 101, the second dot group 102, and the third dot group 103 is formed.

  Next, the detection pattern 100 is detected by the two-dimensional sensor 30, the image information of the detection pattern 100 is acquired, the image information of the detection pattern 100 is analyzed, and the two-dimensional frequency characteristic of the detection pattern 100 is acquired. Then, based on the two-dimensional frequency characteristics, a printing positional deviation (printing positional deviation in the main scanning direction) between the dots constituting the first dot group 101 and the dots constituting the second dot group 102; A conveyance shift (a printing position shift in the sub-scanning direction) between the dots constituting the first dot group 101 and the dots constituting the third dot group 103 is detected.

  As a result, the recording apparatus of the present embodiment can detect a positional deviation of printing in the main scanning direction and the sub-scanning direction.

(Second Embodiment)
Next, a second embodiment will be described.

  Multiple recording heads 6 that print dots of the same color constitute a recording head group, and a recording device that speeds up image formation and multiple recording heads 6 that print dots of different colors constitute a recording head group. In a recording apparatus that performs image formation, it is necessary to adjust the positional deviation of printing in the main scanning direction for each recording head 6.

  For this reason, in the present embodiment, the detection pattern 100 is formed on the recording medium 16 for each recording head 6, and the positional deviation of printing in the main scanning direction is detected for each recording head 6. As a result, the printing position deviation in the main scanning direction can be adjusted for each recording head 6 based on the printing position deviation in the main scanning direction detected for each recording head 6. Hereinafter, the second embodiment will be described in detail.

  The recording apparatus of the present embodiment forms a detection pattern 100 composed of the first dot group 101, the second dot group 102, and the third dot group 103 on the recording medium 16 for each recording head 6.

  Then, the detection pattern 100 formed for each recording head 6 is detected using the two-dimensional sensor 30, and the image information of the detection pattern 100 is acquired for each recording head 6. Then, two-dimensional frequency analysis is performed on the acquired image information of the detection pattern 100 for each recording head 6, and position information (frequency component) of each dot constituting the detection pattern 100 is acquired for each recording head 6.

  Next, based on the positional information (frequency component) of each dot constituting the detection pattern 100, the positional deviation of printing between the dots constituting the first dot group 101 and the dots constituting the second dot group 102 is determined. Detect for each recording head 6.

  Next, a correction value for adjusting the printing timing signal at the time of the backward printing is calculated for each recording head 6 based on the detected positional deviation of the printing. Then, the correction value calculated for each recording head 6 is stored in the sub-storage unit 119, and printing is performed in the main scanning direction using the correction value stored in the sub-storage unit 119 at the time of image formation. As a result, the printing position deviation in the main scanning direction can be adjusted for each recording head 6 based on the printing position deviation in the main scanning direction detected for each recording head 6.

(Third embodiment)
Next, a third embodiment will be described.

  As in the second embodiment, in a recording apparatus in which a plurality of recording heads 6 are arranged to form a recording head group and perform image formation, an assembly error of each recording head 6 affects printing. For this reason, it is necessary to correct the assembly error between the recording heads 6.

  The recording apparatus of the present embodiment corrects the assembly error of the recording head 6 in the main scanning direction. Thereby, it is possible to reduce the positional deviation of printing due to the assembly error in the main scanning direction. Hereinafter, a method for correcting the assembly error in the main scanning direction will be described. In addition, before correcting the assembly error, it is necessary to correct the positional deviation of printing during the forward pass and the return pass for each recording head 6.

  First, using a reference recording head (reference head), dots constituting the first dot group 101 are printed at predetermined intervals in the main scanning direction and the sub-scanning direction, and the first dot group 101 is printed. It is formed on the recording medium 16. The dot interval can be freely set.

  Next, using the recording head (adjustment head) that is subject to positional deviation adjustment, the dots constituting the second dot group 102 are printed in the middle of the dots constituting the first dot group 101, and the second dot group 102 is recorded. Form on medium 16.

  In the ideal assembled state, the dots constituting the first dot group 101 and the dots constituting the second dot group 102 are formed at equal intervals in the main scanning direction as shown in FIG. Become.

  However, when the adjustment head has an assembly error in the main scanning direction with respect to the reference head, as shown in FIG. 21A, the dots constituting the second dot group 102 at the main scanning position different from the ideal position. Will be printed, and a printing position shift in the main scanning direction will occur.

  The recording apparatus of the present embodiment detects the detection pattern 100 configured by the first dot group 101 and the second dot group 102 shown in FIG. 21A by the two-dimensional sensor 30, and acquires image information of the detection pattern 100. . Then, two-dimensional frequency analysis is performed on the image information of the detection pattern 100, and position information of each dot constituting the detection pattern 100 is acquired. As a result, as shown in FIG. 21B, in the frequency component on the X-axis, the positional deviation component of the second dot group 102 formed by the adjustment head is a frequency component different from the frequency component in the ideal state. Will appear. That is, a frequency component different from the frequency component from which the reference frequency is obtained appears. For this reason, the assembly error amount in the main scanning direction can be grasped.

  The recording apparatus of the present embodiment compares the frequency component in the main scanning direction shown in FIG. 21B with the reference frequency in the main scanning direction (frequency component in the ideal state), and calculates the difference, thereby calculating the main difference. It is possible to detect a positional deviation of printing in the scanning direction. For example, if there is no print misalignment in the main scanning direction, the reference frequency (ideal frequency component) in the main scan direction is acquired and the difference becomes zero. It can be detected that no occurrence has occurred (that no assembly error has occurred). Also, if there is a print misalignment in the main scanning direction, a frequency component different from the reference frequency (ideal frequency component) is obtained and a difference is obtained. It is possible to detect the occurrence of (that is, an assembly error has occurred).

  Note that the positional deviation adjustment of the printing in the main scanning direction is performed by adjusting the frequency component in the main scanning direction (frequency component different from the reference frequency (frequency component in the ideal state)) acquired when the positional deviation occurs and a predetermined main scanning direction. If the difference from the reference frequency (frequency component in the ideal state) is obtained, and the print timing signal at the time of return pass printing is adjusted based on the difference, the print position deviation in the main scanning direction can be adjusted.

(Fourth embodiment)
Next, a fourth embodiment will be described.

  In the third embodiment, the assembly error in the main scanning direction has been described. In the fourth embodiment, an assembly error in the sub-scanning direction will be described.

  First, using a reference recording head (reference head), dots constituting the first dot group 101 are printed at predetermined intervals in the main scanning direction, and the first dot group 101 is formed on the recording medium 16. To do. The dot interval can be freely set.

  Next, by using a recording head (adjustment head) that is subject to positional deviation adjustment, the second dot group is located at a position separated from the dots constituting the first dot group 101 by a prescribed pixel (sub-scanning printing prescribed width) in the sub-scanning direction. The dots constituting 102 are printed to form the second dot group 102.

  In an ideal assembled state, the dots constituting the first dot group 101 and the dots constituting the second dot group 102 are formed at equal intervals in the sub-scanning direction as shown in FIG. Become.

  However, when the adjustment head has an assembly error in the sub-scanning direction with respect to the reference head, as shown in FIG. 23A, the dots constituting the second dot group 102 at a sub-scanning position different from the ideal position. Will be printed, and printing misalignment in the sub-scanning direction will occur.

  The recording apparatus of this embodiment detects the detection pattern 100 configured by the first dot group 101 and the second dot group 102 shown in FIG. 23A by the two-dimensional sensor 30, and acquires image information of the detection pattern 100. . Then, two-dimensional frequency analysis is performed on the image information of the detection pattern 100, and position information of each dot constituting the detection pattern 100 is acquired. As a result, as shown in FIG. 23B, in the frequency component on the Y-axis, the positional deviation component of the second dot group 102 formed by the adjustment head is a frequency component different from the frequency component in the ideal state. Will appear. That is, a frequency component different from the frequency component from which the reference frequency is obtained appears. For this reason, the assembly error amount in the sub-scanning direction can be grasped.

  The printing apparatus according to the present embodiment compares the frequency component in the sub-scanning direction shown in FIG. 23B with the reference frequency in the sub-scanning direction (the frequency component in the ideal state), and calculates the difference. It is possible to detect a positional deviation of printing in the scanning direction. For example, when there is no misregistration in the sub-scanning direction, the reference frequency (ideal frequency component) in the sub-scanning direction is acquired and the difference becomes zero. It can be detected that no occurrence has occurred (that no assembly error has occurred). Also, if there is a print misalignment in the sub-scanning direction, a frequency component different from the reference frequency (ideal frequency component) is acquired and a difference is obtained. It is possible to detect the occurrence of (that is, an assembly error has occurred).

  Note that the positional deviation adjustment of the printing in the sub-scanning direction is performed by adjusting the frequency component in the sub-scanning direction (frequency component different from the reference frequency (frequency component in the ideal state)) acquired when the positional deviation occurs, and a predetermined sub-scanning direction. If the difference from the reference frequency (frequency component in the ideal state) is obtained and the nozzle for printing is adjusted based on the difference, the printing position deviation in the sub-scanning direction can be adjusted.

  The above-described embodiment is a preferred embodiment of the present invention, and the scope of the present invention is not limited to the above-described embodiment alone, and various modifications are made without departing from the gist of the present invention. Implementation is possible.

  For example, in the above embodiment, the first dot group 101 ′ shown on the upstream side of the nozzle shown in FIG. 6 uses the nozzles on the downstream side of the nozzle to form the second dot group 102 and the third dot group 103 on the recording medium 16. In this case, the dots constituting the first dot group 101 ′ are printed on the recording medium 16 at predetermined intervals using the nozzle upstream of the nozzle. Further, the second dot group 102 ′ and the third dot group 103 ′ (not shown) that constitute the detection pattern 100 together with the first dot group 101 ′ shown in FIG. 6 are the first dots shown in FIG. The recording medium 16 in which the group 101 ′ is formed is transported by a distance corresponding to one transport unit, and then formed using a nozzle on the downstream side of the nozzle. However, if the detection pattern 100 can be formed, it can be formed by the following method.

  For example, the first dot group 101 ′ shown on the upstream side of the nozzle shown in FIG. 6 uses the nozzle on the downstream side of the nozzle to form the second dot group 102 and the third dot group 103 on the recording medium 16, and then the carriage 5 The dots constituting the first dot group 101 ′ are printed on the recording medium 16 at predetermined intervals using the nozzles on the upstream side of the nozzle while moving and scanning in the forward direction. Further, the second dot group 102 ′ and the third dot group 103 ′ (not shown) that constitute the detection pattern 100 together with the first dot group 101 ′ shown in FIG. 6 are the first dots shown in FIG. After the recording medium 16 in which the group 101 ′ is formed is transported by a distance corresponding to one transport unit, the recording medium 16 is formed using a nozzle on the downstream side of the nozzle. The nozzle used when forming the third dot group 103 is not limited to the nozzle on the downstream side of the nozzle, and can be read at once by the two-dimensional sensor 30 from the nozzle used when forming the second dot group 102. Within this range, it is possible to use a nozzle located at a position separated by a predetermined amount with respect to the transport direction.

  In the recording apparatus of the present embodiment, when forming a color image, the two-dimensional sensor 30 is configured so that color information can be processed, and in the two-dimensional frequency analysis, the pixel information is also expressed by the color information. By constructing to process, it is possible to perform the same processing as in the above-described embodiment.

  Further, the control operation of each unit constituting the recording apparatus of the present embodiment described above can be executed using hardware, software, or a combined configuration of both.

  In the case of executing processing using software, it is possible to install and execute a program in which a processing sequence is recorded in a memory in a computer incorporated in dedicated hardware. Alternatively, the program can be installed and executed on a general-purpose computer capable of executing various processes.

  For example, the program can be recorded in advance on a hard disk or ROM (Read Only Memory) as a recording medium. Alternatively, the program can be stored (recorded) temporarily or permanently in a removable recording medium. Such a removable recording medium can be provided as so-called package software. The removable recording medium includes a floppy (registered trademark) disk, a CD-ROM (Compact Disc Read Only Memory), an MO (Magneto optical) disk, a DVD (Digital Versatile Disc), a magnetic disk, a semiconductor memory, and the like.

  The program is installed in the computer from the removable recording medium as described above. In addition, it is wirelessly transferred from the download site to the computer. In addition, it is transferred to the computer via a network by wire.

  The recording apparatus according to the present embodiment is not only executed in time series according to the processing operation described in the above embodiment, but also the processing capability of the apparatus that executes the process, or in parallel or individually as required. It is also possible to build to run on

  The present invention is suitable for an ink jet recording apparatus.

DESCRIPTION OF SYMBOLS 5 Carriage 6 Recording head 15 Conveyance roller 61 Nozzle row 16 Recording medium 30 Two-dimensional sensor 41 Encoder sensor 40 Encoder sheet 100 Detection pattern 101 1st dot group 102 2nd dot group 103 3rd dot group 107 Control part 109 Main scanning driver 111 Recording head driver 112 Paper transport unit 113 Sub-scan driver 118 Main storage unit 119 Sub storage unit 120 Image processing unit 121 Adjustment pattern generation unit

JP 2004-358759 A

Claims (8)

A recording head provided with a nozzle array in which a plurality of nozzles for ejecting ink are arranged in the conveyance direction of the recording medium;
A carriage on which the recording head is mounted;
Moving means for reciprocating the carriage in a direction orthogonal to the conveyance direction of the recording medium;
Conveying means for conveying the recording medium;
Discharge control means for discharging ink from the nozzles at an arbitrary timing during reciprocation of the carriage, printing dots on the recording medium with the ink, and forming a detection pattern;
A two-dimensional sensor that detects the detection pattern formed on the recording medium and acquires image information of the detection pattern;
Analyzing the image information of the detection pattern acquired by the two-dimensional sensor, and acquiring the two-dimensional frequency characteristics of the detection pattern;
Detecting means for detecting a positional deviation of printing of dots printed when the carriage is reciprocated based on the two-dimensional frequency characteristic acquired by the analyzing means;
The discharge control means includes
During the forward movement of the carriage, ink is ejected a plurality of times at regular intervals in a direction orthogonal to the transport direction using nozzles upstream of the transport direction among the nozzles of the nozzle row, and the plurality of times First dot group forming means for forming a first dot group on the recording medium with the ink of
After the recording medium is transported by a predetermined amount by the transporting means, when the carriage moves backward, the first nozzle group is used to move the first dot group downstream from the nozzles forming the first dot group by using a predetermined amount of the first dot group. A second ink is formed by ejecting ink a plurality of times at a timing when dots are printed at the center positions of two adjacent points among the dots constituting the dot group, and forming a second dot group on the recording medium by the plurality of times of ink. Dot group forming means;
When the carriage moves backward, the first dot group is configured in a direction perpendicular to the transport direction by using a nozzle located at a predetermined distance from the nozzle forming the second dot group in the transport direction. A third dot that ejects ink a plurality of times at the timing when the dot and the dots constituting the second dot group are printed, and forms a third dot group on the recording medium by the plurality of times of ink. Group forming means,
The recording apparatus, wherein the detection pattern configured by the first dot group, the second dot group, and the third dot group is formed. The detection means includes
Based on the two-dimensional frequency characteristics acquired by the analyzing means, the positional deviation of printing between the dots constituting the first dot group and the dots constituting the second dot group, and the first dot group are constituted. The recording apparatus according to claim 1, wherein a printing positional deviation between a dot to be printed and a dot constituting the third dot group is detected. The detection means includes
Of the two-dimensional frequency characteristics acquired by the analyzing means, the frequency characteristics in the direction orthogonal to the transport direction and the reference frequency in the direction orthogonal to the predetermined transport direction are compared, and the first dot group A positional deviation of printing between the dots constituting the second dot group and the dots constituting the second dot group,
Of the two-dimensional frequency characteristics acquired by the analyzing means, the frequency characteristics in the transport direction are compared with a predetermined reference frequency in the transport direction, and the dots constituting the first dot group and the third The recording apparatus according to claim 2, wherein a positional deviation of printing between the dots constituting the dot group is detected. The detection means includes
Frequency characteristics in a direction orthogonal to the transport direction obtained from the dots constituting the first dot group and the dots constituting the second dot group, and the transport direction obtained from the dots constituting the third dot group And a frequency characteristic in a direction orthogonal to the first, and detecting a positional deviation of printing between the dots constituting the first dot group and the dots constituting the second dot group,
Frequency characteristics in the carrying direction obtained from dots constituting the first dot group and dots constituting the third dot group, dots constituting the first dot group, and dots constituting the third dot group And a frequency characteristic in the carrying direction obtained from the above, and detecting a positional deviation of printing between the dots constituting the first dot group and the dots constituting the third dot group. The recording apparatus according to claim 2. The discharge control means includes
When there are a plurality of the recording heads, the detection pattern constituted by the first dot group, the second dot group, and the third dot group is formed for each recording head,
The two-dimensional sensor is
Detecting the detection pattern for each recording head formed on the recording medium, obtaining image information of the detection pattern for each recording head;
The analysis means includes
Analyzing the image information of the detection pattern for each recording head acquired by the two-dimensional sensor, acquiring the two-dimensional frequency characteristics of the detection pattern for each recording head,
The detection means includes
Based on the two-dimensional frequency characteristics of the detection pattern for each recording head acquired by the analysis means, the positional deviation of printing between the dots constituting the first dot group and the dots constituting the second dot group is determined. 3. The recording apparatus according to claim 2, wherein detection is performed for each recording head. The discharge control means includes
During forward movement, ink is ejected a plurality of times at regular intervals from the nozzle of the recording head, which is a reference for positional deviation adjustment, in a direction orthogonal to the transport direction, and the first dot group is formed on the recording medium by the plurality of times of ink. Forming,
During the backward movement, ink is ejected a plurality of times at the timing at which dots are formed at the center positions of two adjacent dots among the dots constituting the first dot group from the nozzles of the recording head that is subject to positional deviation adjustment. Forming a second dot group on the recording medium with the ink, and forming a detection pattern composed of the first dot group and the second dot group on the recording medium,
The detection means includes
The dots constituting the first dot group and the dots constituting the second dot group formed in a direction orthogonal to the transport direction based on the two-dimensional frequency characteristics of the detection pattern formed by the first forming means. 6. The recording apparatus according to claim 2, wherein a positional deviation of printing between the first and second printing positions is detected. The discharge control means includes
During forward movement, ink is ejected a plurality of times at regular intervals from the nozzle of the recording head, which is a reference for positional deviation adjustment, in a direction orthogonal to the transport direction, and the first dot group is formed on the recording medium by the plurality of times of ink. Forming,
During the backward movement, the ink is ejected a plurality of times at a timing when a dot is formed at a position away from a dot constituting the first dot group by a specified amount in the transport direction from the nozzle of the recording head to be adjusted for positional deviation, A second forming unit configured to form a second dot group on the recording medium by a plurality of times of ink and to form a detection pattern including the first dot group and the second dot group on the recording medium; And
The detection means includes
Based on the two-dimensional frequency characteristics of the detection pattern formed by the second forming means, between the dots constituting the first dot group and the dots constituting the second dot group formed in the transport direction. The recording apparatus according to any one of claims 2 to 6, wherein a positional deviation of printing is detected. A recording head provided with a nozzle array in which a plurality of nozzles for ejecting ink are arranged in the conveyance direction of the recording medium;
A carriage on which the recording head is mounted;
Moving means for reciprocating the carriage in a direction orthogonal to the conveyance direction of the recording medium;
Conveying means for conveying the recording medium;
Discharge control means for discharging ink from the nozzles at an arbitrary timing during reciprocation of the carriage, printing dots on the recording medium with the ink, and forming a detection pattern;
A two-dimensional sensor that detects the detection pattern formed on the recording medium and acquires image information of the detection pattern;
Analyzing the image information of the detection pattern, and obtaining the two-dimensional frequency characteristics of the detection pattern;
Detecting means for detecting a positional deviation of printing of dots printed when the carriage is reciprocated based on the two-dimensional frequency characteristics, and a control method performed by a recording apparatus comprising:
The discharge control means includes
During the forward movement of the carriage, ink is ejected a plurality of times at regular intervals in a direction orthogonal to the transport direction using nozzles upstream of the transport direction among the nozzles of the nozzle row, and the plurality of times A first dot group forming step for forming a first dot group on the recording medium with the ink of
After the recording medium is transported by a predetermined amount by the transporting means, when the carriage moves backward, the first nozzle group is used to move the first dot group downstream from the nozzles forming the first dot group by using a predetermined amount of the first dot group. A second ink is formed by ejecting ink a plurality of times at a timing when dots are printed at the center positions of two adjacent points among the dots constituting the dot group, and forming a second dot group on the recording medium by the plurality of times of ink. A dot group forming step;
When the carriage moves backward, the first dot group is configured in a direction perpendicular to the transport direction by using a nozzle located at a predetermined distance from the nozzle forming the second dot group in the transport direction. A third dot that ejects ink a plurality of times at the timing when the dot and the dots constituting the second dot group are printed, and forms a third dot group on the recording medium by the plurality of times of ink. And a group formation process,
A control method comprising: forming the detection pattern including the first dot group, the second dot group, and the third dot group.

Images