JP2006015595A - Printer, computer program, printing system, and method of printing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a printer capable of adequately adjusting a forming position of each of dots formed by a plurality of print heads in a carriage movement direction. <P>SOLUTION: A printing pattern is adapted to carry out adjustment of positional deviation for adjusting deviation of dot forming positions in the movement direction between a dot formed by first movement of an ink ejection section group unit having a plurality of ink ejection section groups and a dot formed by second movement of the ink ejection section group unit. The printing pattern is printed such that ink droplets are ejected to a region assigned to an ink ejection section in the first ink ejection section group during the first movement and ink droplets are ejected to a region assigned to an ink ejection section in a second ink ejection section group during the second movement. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a printing apparatus having a plurality of ink ejection units, a computer program, a printing system, and a printing method.

2. Description of the Related Art Conventionally, as a printing apparatus having a plurality of ink ejection unit groups, an inkjet printer that includes a print head that ejects ink and performs printing by forming dots on a medium using the ejected ink is known (for example, Patent Document 1). reference). As such an ink jet printer, one image can be printed at high speed on a large size printing paper (for example, JIS standard A row 0 paper, B row 0 paper or roll paper) using a plurality of print heads. Large inkjet printers are being considered.
Such a large inkjet printer has a carriage on which a plurality of print heads are mounted at appropriate intervals, and each of the print heads discharges ink while being moved by a predetermined moving mechanism. It is possible to print one image. For this reason, it is necessary to adjust the relative positions of dots formed by ink ejected from each print head toward a predetermined target position. For example, when performing so-called `` bidirectional printing '' in which the carriage is reciprocated and ink is ejected in each of the forward movement and the backward movement, printing is performed in both the forward movement and the backward movement. It is necessary to adjust the position of dots formed by the ink droplets ejected in this way. As a method of adjusting the position of the dot formed by the movement in the forward direction and the movement in the backward direction, first, a print pattern for determining the adjustment amount is printed, and the dot pattern is determined based on the printed print pattern. Adjust the position. The print pattern is, for example, a plurality of vertical lines extending in a direction orthogonal to the moving direction at a predetermined interval in the moving direction with ink droplets ejected by the movement in the forward direction. Use to print. Next, a plurality of vertical lines extending in a direction orthogonal to the movement direction at a predetermined interval in the movement direction are separated from the predetermined print head by ink droplets ejected by movement in the backward direction. A printing pattern is printed by printing using. At this time, the vertical line printed by the movement in the backward direction is printed so as to be linearly connected to the vertical line printed by the movement in the forward direction when the vertical line is printed at an ideal position. Is done. The vertical line printed by the movement in the backward direction is slightly different from the ideal position of the vertical line in the carriage movement direction relative to the vertical line printed by the movement in the forward direction. Printed. Also, when printing such a print pattern, in order to shorten the time required for printing, after printing a vertical line by moving in the forward direction, printing a vertical line by moving in the backward direction The printing paper is conveyed all at once to the position where the vertical line is to be printed.
JP-A-9-262992

  As described above, in the print pattern, when a vertical line is printed by movement in the backward direction, the printing paper is conveyed all at once, and the vertical line formed by movement in the forward direction and movement in the backward direction is Both are formed by a single movement of the carriage. That is, the vertical line of the print pattern is configured with dots formed at the same interval as the nozzle pitch in the transport direction. However, a high-quality image that is printed by appropriately adjusting the dot formation position is often printed by, for example, an interlace method, and the image is formed with dots that are finer than the nozzle pitch. It will be. That is, by the first movement of the carriage, dot lines formed by the subsequent movement of the carriage are formed between the plurality of dot lines formed along the movement direction. Therefore, the dot formation method when the print pattern is printed is different from the dot formation method for forming an image when actually printing. Therefore, based on the print pattern printed by the conventional method, for example, the position in the movement direction of the dots formed by the movement in the forward direction and the position in the movement direction of the dots formed by the movement in the backward direction There is a problem that even if the amount of deviation is adjusted, there is a fear that the amount of deviation is not adjusted appropriately.

  The present invention has been made in view of such a problem, and a printing apparatus and a computer program that can more appropriately adjust the formation positions of dots formed by a plurality of print heads in the carriage movement direction. An object of the present invention is to provide a printing system and a printing method.

  The main invention is: (a) an ink discharge unit group unit having at least two ink discharge unit groups each including a plurality of ink discharge units for discharging ink droplets to form dots on a print medium; and (b) the ink A moving unit for moving the ejection unit group unit along a predetermined movement direction; and (c) ejecting ink from each of the ink ejection units to the area allocated to each of the ink ejection units, and A control unit that allows one image to be printed by two ink ejection unit groups, the dots formed by the first movement of the ink ejection unit group, and the ink ejection unit group A print pattern for executing a positional deviation adjustment for adjusting a deviation of a dot formation position in the movement direction with a dot formed by the second movement of the unit is represented by the ink ejection unit group unit. In the first movement of the ink jet, ink droplets are ejected from the ink ejection section to an area allocated to the ink ejection section provided in the first ink ejection section group, and in the second movement, A control unit capable of printing by ejecting ink droplets from the ink ejection unit in an area allocated to the ink ejection unit provided in the second ink ejection unit group different from the first ink ejection unit group; , (D).

  Other features of the present invention will be clarified by the description of the present specification and the accompanying drawings.

  At least the following will be made clear by the description of the present specification and the accompanying drawings.

  (A) an ink discharge unit group unit having at least two ink discharge unit groups each having a plurality of ink discharge units for discharging ink droplets to form dots on a print medium; and (b) the ink discharge unit group unit. A moving part for moving the ink along a predetermined moving direction, and (c) discharging at least two inks by discharging ink from each ink discharging part to the area allocated to each of the ink discharging parts. A control unit that allows one image to be printed by the group of dots, the dots formed by the first movement of the ink ejection unit group unit, and the second of the ink ejection unit group unit. A print pattern for executing a positional deviation adjustment for adjusting a deviation of the dot formation position in the movement direction with respect to the dots formed by the movement of the first ink ejection unit group unit. When moving, ink droplets are ejected from the ink ejection unit to an area allocated to the ink ejection unit provided in the first ink ejection unit group, and the first ink ejection unit is moved during the second movement. A control unit capable of printing by ejecting ink droplets from the ink ejection unit in an area allocated to the ink ejection unit provided in the second ink ejection unit group different from the group; and (d) This is a printing apparatus.

  According to such a printing apparatus, the printing pattern for executing the positional deviation adjustment for adjusting the deviation of the dot formation position in the movement direction is the first ink ejection during the first movement of the ink ejection unit group unit. The ink droplets are ejected from the ink ejection part of the part group, and the ink droplets are ejected from the ink ejection part of the second ink ejection part group during the second movement. For this reason, when the positional deviation adjustment is executed based on the printed printing pattern, the first ink ejection unit group and the second ink ejection unit group are formed when the ink ejection unit group unit moves differently. It is possible to adjust the displacement of the position in the moving direction of the dots. Further, the print pattern is formed by ejecting ink to the area allocated to each ink ejection unit, as in the case of forming one image in the first and second ink ejection unit groups. For this reason, when the misregistration adjustment is executed based on the print pattern, more appropriate adjustment is executed when the image is actually printed, and more accurate adjustment is executed. A good image can be printed even if the ink ejection unit group is used.

In this printing apparatus, the first ink ejection unit group is the ink ejection unit group other than the ink ejection unit group that is most susceptible to vibration caused by the movement of the ink ejection unit group unit during the first movement. Is desirable.
According to such a printing apparatus, since the first ink ejection unit group is an ink ejection unit group other than the ink ejection unit group that is most susceptible to vibration due to movement, the first ink ejection unit group is moved when the ink ejection unit group unit is moved. The behavior of the discharge unit group is stable. For this reason, since the dots formed in the first ink discharge unit group are formed at stable positions, the positional deviation adjustment is executed with reference to the dots formed in the first ink discharge unit group. Thus, it is possible to accurately adjust the positions of the dots formed in the second ink discharge unit group.

In the printing apparatus, it is preferable that the first ink discharge unit group is an ink discharge unit group that is less susceptible to vibration due to movement of the ink discharge unit group unit than the second ink discharge unit group.
According to such a printing apparatus, since the first ink ejection unit group is an ink ejection unit group that is not easily subjected to vibration due to movement, the behavior of the first ink ejection unit group is more improved when the ink ejection unit group unit is moved. stable. That is, the dots formed by the first ink ejection unit group are formed at more stable positions. For this reason, it is possible to adjust the position of the dots formed in the second ink discharge unit group with higher accuracy by performing the positional deviation adjustment with reference to the dots formed in the first ink discharge unit group. Is possible.

In such a printing apparatus, the ink discharge unit group unit is moved by an external force, and the first ink discharge unit group is present at a position farthest from a portion where the external force acts in a direction crossing the moving direction. It is desirable to be an ink ejection unit group other than the ink ejection unit group.
Since the size of the ink ejection unit having at least two ink ejection unit groups is larger than that of each ink ejection unit group, it is separated from the ink ejection unit group located near the portion where the external force acts on the ink ejection unit. Ink ejection unit groups located at the The behavior of the ink ejection unit during the movement of the ink ejection unit group unit is such that the ink ejection unit group existing at the position farthest from the site where the external force acts is the most unstable in the direction intersecting the movement direction and vibrates. It's easy to do. For this reason, by setting the first ink discharge unit group to be an ink discharge unit group other than the ink discharge unit group that is located farthest from the site where the external force acts, at least the first ink discharge unit group is in a stable state. It is possible to form dots. The positions of the dots formed in the first ink discharge unit group in a stable state have little variation, so the dots formed in the first ink discharge unit group and the second ink discharge unit group are formed. It is possible to adjust the dot to be adjusted to an appropriate position in the moving direction.

In such a printing apparatus, it is desirable that the first ink ejection unit group be present at a position closer to a portion where the external force acts than the second ink ejection unit in a direction intersecting the moving direction.
According to such a printing apparatus, the first ink ejection unit group is located closer to the portion where the external force acts in the direction intersecting the movement direction than the second ink ejection unit group. By adjusting the positions of the dots formed in the second ink discharge section with reference to the dots formed in step 1, the dots formed in each ink discharge section group can be formed at more appropriate positions. Is possible.

In such a printing apparatus, there are two parts where the external force acts, and the first ink ejection unit group is located closer to the center of the two parts where the external force acts than the second ink ejection part. It is desirable to do.
At the center of the two parts where the external force acts, the behavior during movement is most stable in the ink ejection unit group unit. For this reason, the first ink ejection unit group is an ink ejection unit group located on the side closer to the center of the two parts to which the external force acts, so that the ink in the state most stable to the dots constituting the print pattern It is possible to include dots formed by the ink ejection unit group that ejects. For this reason, by using the position of the dot formed in the first ink discharge unit group that discharges ink in the most stable state as a reference, the position of the dot formed in the second ink discharge unit group is It is possible to adjust to the most appropriate position. For this reason, since dots formed by any ink discharge unit group are adjusted to a more appropriate position, one good image can be printed using a plurality of ink discharge unit groups. Is possible.

In this printing apparatus, each of the ink ejection unit groups is driven based on a single reference ejection signal for ejecting ink from the ink ejection unit, and the reference ejection signal of the first ink ejection unit group It is preferable that the positional deviation adjustment is performed by adjusting the timing of the reference ejection signal of the second ink ejection unit group with reference to the timing of
According to such a printing apparatus, since the dot formation position is adjusted by adjusting the timing of the reference ejection signal in the plurality of ink ejection unit groups, the dots formed in the first ink ejection unit group Thus, it is possible to easily and accurately execute the positional deviation adjustment of the dots formed in the second ink discharge unit group.

In such a printing apparatus, the ink discharge unit group unit can reciprocate, the first movement is movement in the forward direction of the ink discharge unit group unit, and the second movement is the ink discharge unit. It is desirable to move the group unit in the return direction.
According to such a printing apparatus, while the moving body reciprocates, the ink is respectively discharged from the first ink discharge unit group by the forward movement and from the second ink discharge unit group by the backward movement. When printing one image by ejecting, it is possible to appropriately adjust the positional deviation between dots that are provided in different ink ejection unit groups and formed by ink ejected from each ink ejection unit group. Is possible. For this reason, it is possible to print one good image while reciprocating using the first ink discharge unit group and the second ink discharge unit group.

In such a printing apparatus, the ink discharge unit group unit can reciprocate, and the first movement is a movement of the ink discharge unit group unit in a specific direction in a forward direction or a return direction, and the second movement. May be a movement in the specific direction executed at a timing different from that of the first movement.
According to such a printing apparatus, the movable body ejects ink from the first ink ejection unit group while moving in a predetermined direction, and from the second ink ejection unit group by movement in a predetermined direction at different timings. Thus, when printing one image, it is possible to appropriately adjust the positional deviation between dots that are provided in different ink ejection unit groups and formed with ink ejected from each ink ejection unit group. is there. Therefore, it is possible to print one good image while moving in a specific direction using the first ink discharge unit group and the second ink discharge unit group.

In this printing apparatus, the printing pattern includes a plurality of sub-patterns formed by ink respectively ejected from the first ink ejection unit group and the second ink ejection unit group, and the positional deviation adjustment is performed. Formation of dots formed by the first ink ejection unit group and dots formed by the second ink ejection unit group in the sub-patterns and having a plurality of adjustment amounts It is desirable that the positional shift amount is the adjustment amount that differs for each sub-pattern.
According to such a printing apparatus, each of the plurality of sub-patterns included in the printing pattern is formed of ink ejected from the first ink ejection unit group and the second ink ejection unit group, and The sub-pattern is formed with an adjustment amount in which the shift amount of the dot formation position differs. For this reason, it is possible to easily print a good image by extracting a well-printed sub-pattern, adjusting the adjustment amount when the extracted sub-pattern is formed, and printing the image. It is.

In such a printing apparatus, the first ink discharge unit group and the second discharge unit group each include an achromatic ink discharge unit that discharges achromatic ink and a chromatic ink discharge unit that discharges chromatic ink. It is desirable that the misregistration adjustment can be performed differently when the achromatic color ink is ejected to execute the achromatic color printing and when the chromatic color ink is ejected to execute the chromatic color printing.
When executing achromatic color printing and when executing chromatic color printing, not only the ink to be used but also the ink discharge section to be used is different. For this reason, each ink color dot is formed at a different position. For this reason, when performing achromatic color printing and when executing chromatic color printing, it is possible to perform different misalignment adjustments, so that appropriate adjustments can be made for achromatic color printing and chromatic color printing. In any case, it is possible to print a good image.

In such a printing apparatus, each of the ink ejection unit groups includes a plurality of the chromatic color ink ejection units, and each chromatic color ink ejection unit group ejects different colors of ink for each color, and the chromatic color ink is ejected. When the positional deviation adjustment is executed when forming dots using the printing pattern, it is preferable to print the print pattern with any one of the plurality of chromatic color inks.
According to such a printing apparatus, the print pattern is printed with any one of a plurality of chromatic color inks. Therefore, the print pattern can be formed in a shorter time than printing with all the color inks. It is possible to print and set the adjustment amount. Therefore, when performing chromatic color printing, the print pattern is formed with the ink of the color that should be adjusted most, and the adjustment amount is set, so that the time spent for setting the adjustment amount is shortened and good It is possible to print a chromatic color image.

In such a printing apparatus, it is preferable that the printing pattern is printed with ink of a color mainly used when printing a low gradation portion of an image among the plurality of chromatic color inks.
In printing using chromatic ink, the image quality is particularly affected by a low gradation portion of the image. The low gradation portion is a portion having a low density and is a so-called highlight portion. When a print pattern is printed with ink mainly used in such a low gradation portion and adjustment of misalignment is performed based on the printed print pattern, a plurality of ink ejection unit groups are formed in the low gradation portion. It is possible to more appropriately adjust the position in the moving direction of the dots. Therefore, it is possible to print an image using better chromatic ink.

In such a printing apparatus, it is desirable that the ink ejection unit can form a plurality of types of dots having different sizes, and the printing pattern is formed by dots of any size among the plurality of types of dots. .
According to such a printing apparatus, since the print pattern is printed with one of a plurality of types of dots, the print pattern is printed in a shorter time than when printing with all the size dots. It is possible to set the adjustment amount.

In such a printing apparatus, the ink ejection unit can form a plurality of types of dots having different sizes, and the positional deviation adjustment is acquired based on the print pattern formed by each of the plurality of types of dots. The average value of the adjustment amounts may be set as an adjustment amount for executing the positional deviation adjustment.
According to such a printing apparatus, as compared with the case where only the dots of a predetermined size are subjected to the positional deviation adjustment based on the print pattern formed by the dots of any size among the plurality of types of dots. Since dots of any size are adjusted for positional deviation, it is possible to prevent the formation positions of the dots of each size from greatly deviating from the target position. For this reason, it is possible to print all the images formed by the dots of each size relatively well.

In addition, (a) an ink discharge unit group unit having at least two ink discharge units each including a chromatic color ink discharge unit for discharging chromatic color ink to form a plurality of types of dots having different sizes on a print medium And (b) a moving portion for reciprocating along a predetermined moving direction by an external force acting on two locations of the ink discharge portion group unit, and (c) for discharging ink from the ink discharge portion. Ink is ejected from each of the ink ejection sections to the area allocated to each of the ink ejection sections driven based on a single reference ejection signal, and one of the at least two ink ejection section groups A control unit that allows an image to be printed, the dots formed by the movement of the ink discharge unit group unit in the forward direction, and the return direction of the ink discharge unit group unit The deviation of the dot formation position in the movement direction from the dot formed by movement is different from that of the first ink ejection unit group on the basis of the timing of the reference ejection signal of the first ink ejection unit group. By adjusting the timing of the reference ejection signal of the two ink ejection unit group based on the adjustment amount, when performing chromatic printing by ejecting the chromatic color ink, the positional deviation adjustment for performing the adjustment is performed. When the ink discharge unit group unit moves in the forward direction, a print pattern is provided in the first ink discharge unit group located on the side closer to the center of the two portions where the external force acts. A plurality of sub-patterns are formed by ejecting ink droplets from the ink ejection section to the area allocated to the ink ejection section that ejects ink of the color used mainly when printing low gradation parts And, when moving in the backward direction, a plurality of sub-patterns are formed by ejecting ink droplets from the ink-ejection unit to an area allocated to the ink-ejection unit provided in the second ink-ejection unit group. Control capable of printing each of the plurality of types of dots with the different adjustment amounts for each, and executing the positional deviation adjustment with an average value of the adjustment amounts acquired based on the printed sub-pattern. And a printing apparatus having (d).
According to such a printing apparatus, since all the effects described above are exhibited, the object of the present invention is achieved most effectively.

  (A) an ink discharge unit group unit having at least two ink discharge units each including a plurality of ink discharge units for discharging ink droplets to form dots on the print medium; and (b) the ink discharge unit. A moving unit for moving the group unit along a predetermined moving direction; and (c) ejecting ink from each of the ink ejecting units to an area allocated to each of the ink ejecting units, A control unit capable of printing one image in the ink discharge unit group; and a dot formed by the first movement of the ink discharge unit group unit on the printing apparatus having (d); A print pattern for executing a positional deviation adjustment for adjusting a deviation of a dot formation position in the movement direction with respect to a dot formed by the second movement of the ink ejection unit group unit is provided. During the first movement of the ejection unit group unit, ink droplets are ejected from the ink ejection unit to an area allocated to the ink ejection unit provided in the first ink ejection unit group, and during the second movement. In addition, in order to realize a function of printing by ejecting ink droplets from the ink ejection unit to an area allocated to the ink ejection unit provided in the second ink ejection unit group different from the first ink ejection unit group. The computer program can also be realized.

  Also, (A) a computer main body, (B) a printing apparatus connected to the computer main body having the following (a) to (d), and (a) ejecting ink droplets to form dots on the printing medium An ink discharge unit group unit having at least two ink discharge unit groups each having a plurality of ink discharge units for performing the operation, and (b) a moving unit for moving the ink discharge unit group unit along a predetermined moving direction. (C) It is possible to cause the at least two ink ejection unit groups to print one image by ejecting ink from the respective ink ejection units to areas assigned to the respective ink ejection units. A control unit configured to move the dots formed by the first movement of the ink discharge unit group unit and the dots formed by the second movement of the ink discharge unit group unit in the movement direction. Oh A print pattern for executing a positional deviation adjustment for adjusting a deviation of the dot forming position is applied to the ink ejection unit provided in the first ink ejection unit group during the first movement of the ink ejection unit group unit. Ink droplets are ejected from the ink ejection unit to the allocated area, and allocated to an ink ejection unit provided in a second ink ejection unit group different from the first ink ejection unit group during the second movement. It is also possible to realize a printing system characterized by having a control unit capable of printing by ejecting ink droplets from the ink ejection unit to the area, and (C).

  In addition, a first ink jet unit along a predetermined moving direction of an ink discharge unit group having at least two ink discharge unit groups each including a plurality of ink discharge units for discharging ink droplets to form dots on a print medium. During the movement, ink droplets are ejected from the ink ejection section to the area allocated to the ink ejection section provided in the first ink ejection section group, and during the second movement along the predetermined movement direction. Printing a print pattern by ejecting ink droplets from the ink ejection section in an area allocated to an ink ejection section provided in a second ink ejection section group different from the first ink ejection section group; Based on the printed print pattern, the dots formed by the first movement of the ink ejection unit group unit and the dots formed by the second movement of the ink ejection unit group unit. And adjusting the deviation of the dot formation position in the moving direction to cause the at least two ink ejection unit groups to eject ink from the respective ink ejection units to areas assigned to the respective ink ejection units. In addition, a printing method characterized by including a step of printing one image can be realized.

=== Example of Printing Apparatus ===
FIG. 1 is a perspective view showing an outline of a color ink jet printer (hereinafter referred to as a color printer) 20 as a printing apparatus that discharges and prints ink from a nozzle row as an ink discharge portion as an embodiment of the present invention. The color printer 20 is an inkjet printer capable of outputting a color image. For example, cyan ink (C) and light cyan ink (light cyan ink, LC) as cyan ink, and magenta ink (M) as magenta ink. ) And light magenta ink (light magenta ink, LM), yellow ink (Y), and black ink (K) are ejected onto various media such as printing paper to form dots. This is an ink jet printer that prints the image. The color ink is not limited to the above six colors, and for example, dark yellow (dark yellow, DY) may be used. Further, the color printer 20 is, for example, a roll paper obtained by winding a printing paper as a printing medium in a roll shape, or a relatively large single-sheet printing paper such as a JIS standard A row 0 paper or B row 0 paper. Is also supported. In the example of FIG. 1, the color printer 20 is provided with roll paper (hereinafter referred to as printing paper).

As shown in the figure, the color printer 20 includes a printing unit 3 that discharges ink and prints on the printing paper P, and a printing paper transport unit 5 that transports the printing paper along a predetermined transport direction. .
The printing unit 3 includes a carriage 28 as an ink discharge unit group that holds at least two print heads 36 as an ink discharge unit group having nozzle rows as a plurality of ink discharge units, and the carriage 28 is used as a printing paper. The carriage motor 30 is moved in a direction substantially orthogonal to the conveyance direction of P (hereinafter referred to as the carriage movement direction) and reciprocally moved. The carriage motor 30 and the carriage motor 30 constitute a moving mechanism and are driven by the carriage motor 30 to move the carriage 28. A metal traction belt 32 to be moved, two guide rails 34 for guiding the carriage 28, a linear encoder 17 fixed to the carriage 28, and a reflective optical sensor 13 for detecting paper, And a linear encoder code plate 19 having slits formed at predetermined intervals. That.

  Two guide rails 34 are provided along the carriage movement direction, and are vertically arranged at intervals in the transport direction, and are supported by frames (not shown) serving as bases at both left and right ends. Yes. At this time, in the two guide rails 34, the lower guide rail 341 is disposed in front of the upper guide rail 342. For this reason, the carriage 28 arranged so as to be bridged between the two guide rails 341 and 342 moves in an inclined state so that the upper part is positioned rearward and the lower part is positioned forward.

  A linear encoder code plate 19 is provided along the guide rail 342 on the upper guide rail 342 on which the carriage 28 is guided. The linear encoder code plate 19 is disposed so as to face the detection portion of the linear encoder 17 fixed to the carriage 28 that moves along the guide rail 34. The linear encoder 17 will be described later.

  The traction belt 32 is fixed to the left and right ends of the carriage 28 and formed in an annular shape, and is disposed at an intermediate position between the upper and lower guide rails 341 and 342 with an interval substantially equal to the length of the guide rails 341 and 342. The two pulleys 44 and 45 are stretched over. One of the pulleys 44 and 45 is fixed to the shaft of the carriage motor 30.

  In the carriage 28 arranged so as to be bridged between the two guide rails 341 and 342, the traction belt 32 is fixed at substantially the center in the vertical direction at the left and right end portions. In the color printer 20, the power of the carriage motor 30 is transmitted by the traction belt 32, and the carriage 28 is pulled by the traction belt 32 by the transmitted power and moves in the carriage movement direction along the guide rail 34. When the carriage 28 is moved, ink is ejected from the eight print heads 36 provided on the carriage 28, thereby printing an image on the printing paper P fed by the printing paper transport unit 5.

  In the present embodiment, eight print heads 36 are provided on the carriage 28, and these print heads 36 have a plurality of nozzles n for ejecting ink, and are controlled by a head control unit 63 (see FIG. 6) to be described later. Ink is ejected from the nozzle n. The surface of the print head 36 facing the printing paper P has a plurality of nozzle rows N as an ink discharge section in which a plurality of nozzles n are arranged in a row along the transport direction. It is arranged along the direction. The arrangement of the print head 36 and the nozzles n will be described later.

  The printing paper transport unit 5 is provided on the back side of the two guide rails 34. The printing paper transport unit 5 transports the printing paper P below the lower guide rail 341 and the roll paper holding unit 35 that rotatably holds the printing paper P together with the holder 27, and above the upper guide rail 342. A roll paper transport unit 37 and a platen 26 along which the print paper P transported between the roll paper holding unit 35 and the roll paper transport unit 37 are arranged. The platen 26 has a flat surface extending over the entire width of the printing paper P to be conveyed, and this flat surface is inclined so as to face each print head 36 mounted on the carriage 28 that moves in an inclined state at equal intervals. It is provided in the state.

  The holder 27 has a shaft body 27a serving as a rotating shaft in a state where the printing paper P is held, and a guide disk 27b for preventing meandering of the printing paper P to be supplied on both ends of the shaft body 27a. Are provided.

  The roll paper transport unit 37 includes a paper transport roller 24 for transporting the print paper P, a sandwiching roller 29 that is disposed opposite the paper transport roller 24 and sandwiches the print paper P, and a paper transport roller. And a conveyance motor 31 for rotating 24. A drive gear 40 is provided on the shaft of the transport motor 31, and a relay gear 41 that meshes with the drive gear 40 is provided on the shaft of the paper transport roller 24. The power of the transport motor 31 is provided via the drive gear 40 and the relay gear 41. Is transmitted to the paper transport roller 24. That is, the printing paper P held by the holder 27 is sandwiched between the paper transport roller 24 and the sandwiching roller 29, and the printing paper P is transported along the platen 26 by the transport motor 31. A rotary encoder 16 is provided on the shaft of the transport motor 31. The conveyance amount of the printing paper is controlled based on an output signal from the rotary encoder 16.

=== Encoder ===
Next, the linear encoder 17 provided on the carriage 28 will be described. FIG. 2 is an explanatory diagram schematically showing the configuration of the linear encoder 17 attached to the carriage 28.
The linear encoder 17 shown in FIG. 2 includes a light emitting diode 17a, a collimator lens 17b, and a detection processing unit 17c. The detection processing unit 17c includes a plurality of (for example, four) photodiodes 17d, a signal processing circuit 17e, and, for example, two comparators 17fA and 17fB.
When the voltage VCC is applied to both ends of the light emitting diode 17a via a resistor, light is emitted from the light emitting diode 17a. This light is condensed into parallel light by the collimator lens 17 b and passes through the linear encoder code plate 19. The linear encoder code plate 19 is provided with slits at predetermined intervals (for example, 1/180 inch (1 inch = 2.54 cm)).
The parallel light that has passed through the linear encoder code plate 19 enters each photodiode 17d through a fixed slit (not shown), and is converted into an electrical signal. The electric signals output from the four photodiodes 17d are subjected to signal processing in the signal processing circuit 17e, the signals output from the signal processing circuit 17e are compared in the comparators 17fA and 17fB, and the comparison result is output as a pulse. The pulses ENC-A and ENC-B output from the comparators 17fA and 17fB are the outputs of the linear encoder 17.

FIG. 3A is a timing chart showing waveforms of two output signals of the linear encoder 17 during forward rotation of the carriage motor, and FIG. 3B shows waveforms of two output signals of the linear encoder 17 during reverse rotation of the carriage motor. It is a timing chart.
As shown in FIGS. 3A and 3B, the phase of the pulse ENC-A and the pulse ENC-B differ by 90 degrees in both cases of forward rotation and reverse rotation of the carriage motor. When the carriage motor 30 is rotating forward, that is, when the carriage 28 is moving in the carriage movement direction, the pulse ENC-A is 90 degrees out of phase with the pulse ENC-B, as shown in FIG. 3A. When the carriage motor 30 rotates in reverse, the phase of the pulse ENC-A is delayed by 90 degrees from the pulse ENC-B as shown in FIG. 3B. One period T of the pulse ENC-A and the pulse ENC-B is equal to the time during which the carriage 28 moves through the slit interval of the linear encoder code plate 19.

  In the present embodiment, the slit (white portion) width of the linear encoder code plate 19 corresponds to twice the resolution of the color printer 20, for example, 360 dpi here. That is, when the carriage 28 moves in the carriage movement direction, it is detected that the distance corresponding to 360 dpi has been moved each time a pulse is output from the linear encoder 17. Therefore, for example, in the initial operation when the color printer 20 is activated, the home position set in advance as the standby position of the carriage 28 is recognized, and then the pulses output from the linear encoder 17 are counted, whereby the carriage 28 It is possible to detect the position in the carriage movement direction.

  Further, by dividing the pulse output from the linear encoder 17 into equal parts, the position of the carriage 28 can be detected with a higher resolution than the slit of the linear encoder code plate 19. For example, if the pulse output from the linear encoder 17 is divided into four, the position of the carriage 28 can be detected and controlled with an accuracy of 1440 dpi.

=== Configuration of Print Head ===
The configuration of the print head 36 will be described with reference to FIGS. FIG. 4 is an explanatory diagram for explaining an arrangement of nozzles included in the print head 36, and FIG. 5 is a diagram illustrating an arrangement of a plurality of adjacent print heads 36 and a positional relationship between nozzle rows included in the print heads 36. is there.

  As shown in FIG. 4, the print head 36 includes a plurality of nozzles n arranged in a straight line along the transport direction, and has six nozzle rows N as recording portion rows. In this embodiment, the nozzle row N is for each ink color to be ejected, such as a black nozzle row Nk, a cyan nozzle row Nc, a light cyan nozzle row Nlc, a magenta nozzle row Nm, a light magenta nozzle row Nlm, and a yellow nozzle row Ny. There is a line, but it is not limited to this.

  The black nozzle row Nk has 180 nozzles n1 to n180, and each nozzle n is provided with a piezo element (not shown) as a driving element for driving each nozzle n to eject ink droplets. Yes. The nozzles n1,..., N180 of the black nozzle row Nk are arranged at a constant nozzle pitch k · D along the transport direction. Here, D is a dot pitch in the transport direction, and k is an integer of 1 or more. The dot pitch D in the transport direction is equal to the pitch of a horizontal dot row (hereinafter also referred to as a raster line) in which dots are arranged in the carriage movement direction. Hereinafter, the integer k representing the nozzle pitch k · D is simply referred to as “nozzle pitch k”. In the example of FIG. 4, the nozzle pitch k is 4 dots. However, the nozzle pitch k can be set to an arbitrary integer.

  The same applies to the cyan nozzle row Nc, the light cyan nozzle row Nlc, the magenta nozzle row Nm, the light magenta nozzle row Nlm, and the yellow nozzle row Ny. That is, each nozzle row N has 180 nozzles n1 to n180, and is arranged at a constant nozzle pitch k · D along the transport direction.

  At the time of printing, the printing paper P is intermittently transported by a predetermined transporting amount by the printing paper transporting unit 5, and the carriage 28 moves in the carriage moving direction during the intermittent transporting, and ink droplets are ejected from each nozzle n. Is discharged. However, when printing by an interlace method for printing a natural image or the like depending on the printing method, not all nozzles n are always used, and only some nozzles n are used. There is also.

  Of the eight print heads 36a to 36h provided on the carriage 28, four print heads 36 are arranged along the transport direction and arranged in two rows at intervals. Two print head arrays composed of four print heads 36 are arranged side by side in the carriage movement direction. In the print head row arranged in two rows, one print head row 36b, 36d, 36f, 36h is upstream of the other print head row 36a, 36c, 36e, 36g by a distance of about one print head in the transport direction. Arranged on the side. That is, the eight print heads 36a located first from the downstream side of the one print head row and the second print head 36c located so as not to line up in the carriage movement direction. In between, the print head 36b located in the most downstream side of the other print head row | line | column is arrange | positioned. The 180th nozzle of the print head 36a located on the most downstream side of one print head row and the first nozzle of the print head 36b located on the most downstream side of the other print head row are nozzles in the transport direction. They are arranged so as to be separated by the pitch k · D. The 180th nozzle of the print head 36b located on the most downstream side of the other print head row and the first nozzle of the print head 36c located second from the downstream side of the one print head row are transported. The nozzles are arranged so as to be separated by a nozzle pitch k · D in the direction. As described above, the print heads 36 arranged in two rows are arranged such that the first nozzle and the 180th nozzle of the print heads adjacent to each other in the transport direction are separated by the nozzle pitch k · D, respectively. . That is, from the first nozzle of the print head 36a located on the most downstream side in the two print head rows to the 180th nozzle of the print head 36h located on the most upstream side, both are the nozzle pitch k · D in the transport direction. Just placed away. Therefore, in one movement of the carriage 28, for example, when dots are formed at the same position in the carriage movement direction with respect to the printing paper P in each nozzle row N having eight print heads, the nozzle rows of the eight print heads 36 are formed. The dots formed by N are continuously formed at an equal pitch.

  Of the eight print heads 36 provided on the carriage 28, the four print heads 36 a to 36 d are disposed above the traction belt 32, and the remaining four print heads 36 e to 36 h are disposed below the traction belt 32. Has been. Since the positional relationship between the four print heads 36 is the same, the positional relationship between the upper four print heads 36a to 36d will be described as an example here.

  By the way, the power (traction force) of the carriage motor 30 as an external force for moving the carriage 28 acts on two portions where the traction belt 32 is fixed to the carriage 28, that is, the engaging portions S1 and S2. In the carriage 28, the portion close to the action line SL that connects the engaging portions S1 and S2 that act as external force acts is more directly transmitted, so that the vibration during the movement of the carriage 28 is small and the action is small. As the distance from the line SL increases, the vibration increases. That is, the print heads 36 that are most susceptible to vibration due to the movement of the carriage 28 are the print heads 36a and 36h that are disposed at the positions farthest from the action line SL. The print head closest to the midpoint 46 of the action line SL, that is, the center of the engaging portions S1 and S2, and the nozzle row N closest to the centers of the engaging portions S1 and S2 are moved by the movement of the carriage 28. It will be the least susceptible to vibration. Further, between two different print heads 36, one of the two print heads 36 on the side closer to the action line SL is less susceptible to vibration due to movement of the carriage 28 than the other print head 36. Become.

  In FIG. 4, the ink colors of each nozzle row are black nozzle row Nk, cyan nozzle row Nc, light cyan nozzle row Nlc, magenta nozzle row Nm, light magenta nozzle row Nlm, and yellow nozzle row Ny from the left side of the drawing. However, the present invention is not limited to this, and the ink colors of the nozzle arrays N may be arranged in other arrangement orders.

=== Example of Overall Configuration of Printing System ===
Next, an example of the overall configuration of the printing system will be described with reference to FIGS. FIG. 6 is a block diagram illustrating a configuration of a printing system including the color printer 20 described above. FIG. 7 is a block diagram showing a configuration of the image processing unit 38.

  This printing system includes a computer 90 and a color printer 20 as an example of a printing apparatus. The printing system including the color printer 20 and the computer 90 can also be called a “printing apparatus” in a broad sense. The system includes the computer 90, the color printer 20, the CRT 21, a display device (not shown) such as a liquid crystal display device, an input device such as a keyboard and a mouse, a drive device such as a flexible drive device and a CD-ROM drive device. It is constructed from etc.

  In the computer 90, an application program 95 operates under a predetermined operating system. The operating system incorporates a video driver 91, and an application program 95 that performs image retouching or the like performs desired processing on the image to be processed, and also sends an image to the CRT 21 via the video driver 91. it's shown.

  The color printer 20 includes print data and the like from the application program 95, and includes an image processing unit 38, a system controller 54 as a control unit that controls the operation of the entire color printer 20, a main memory 56, and an EEPROM 58. ing. The system controller 54 further includes a carriage motor drive circuit 61 that drives the carriage motor 30, a carry motor drive circuit 62 that drives the carry motor 31, a head control unit 63 that controls the print head 36, and the carriage 28. Are connected to a linear encoder 17 for detecting this operation and a rotary encoder 16 for controlling the transport amount of the printing paper.

  As shown in FIGS. 1 and 6, the color printer 20 described above has a plurality of print heads 36. In the present embodiment, eight print heads 36 are arranged on the carriage 28 at intervals in the vertical direction and the horizontal direction, and each print head 36 is configured to be detachable from the printer body. Yes.

  Further, each print head 36 includes an ink tank 67 that is provided in the print head 36 and stores ink supplied to the print head 36. The print heads 36 each have the head control unit 63 and the image processing unit 38 described above, and each print head 36 can be controlled based on a reference drive signal.

  When the application program 95 issues a print command, the image processing unit 38 provided in the color printer 20 receives the image data from the application program 95 and converts it into print data PD. As shown in FIG. 7, the image processing unit 38 includes a resolution conversion module 97, a color conversion module 98, a halftone module 99, a rasterizer 100, a UI printer interface module 102, and a raster data storage unit 103. A color conversion lookup table LUT, a buffer memory 50, and an image buffer 52.

  The resolution conversion module 97 plays a role of converting the resolution of the color image data formed by the application program 95 into a corresponding print resolution based on information such as the print mode received together with the image data. The image data thus converted in resolution is still image information composed of three color components of RGB. The color conversion module 98 converts RGB image data for each pixel into multi-tone data of a plurality of ink colors that can be used by the color printer 20 while referring to the color conversion lookup table LUT.

  The color-converted multi-gradation data has, for example, 256 gradation values. The halftone module 99 performs so-called halftone processing to generate halftone image data. Here, for example, halftone is an image that is divided into predetermined regions composed of a plurality of regions where pixels can be formed, and the density in each region is divided into large dots, medium dots at a plurality of regions constituting the region. The density of each area is expressed by whether or not to form either a dot or a small dot.

  The halftone image data is rearranged in the desired data order by the rasterizer 100 and output to the raster data storage unit 103 as final print data PD.

  On the other hand, the user interface display module 101 provided in the computer 90 has a function of displaying various user interface windows related to printing and a function of receiving user input in these windows. For example, the user can instruct the user interface display module 101 about the type, size, print mode, and the like of the print paper.

  The UI printer interface module 102 has a function as an interface between the user interface display module 101 and the color printer 20. Interpret the command instructed by the user through the user interface and send various commands COM to the system controller 54 etc. Conversely, interpret the command COM received from the system controller 54 etc. and perform various displays on the user interface Or For example, the instruction related to the type, size, etc. of the printing paper received by the user interface display module 101 is sent to the UI printer interface module 102. The UI printer interface module 102 interprets the instructed instruction, and the system controller The command COM is transmitted to 54.

  The UI printer interface module 102 also has a function as a print mode setting unit. That is, the UI printer interface module 102 is based on the print information received by the user interface display module 101, that is, the resolution of the image to be printed, the information on the nozzle used for printing, the information on the data indicating the transport direction feed amount, and the like. Then, the print mode as the recording mode is determined, print data PD corresponding to this print mode is generated by the halftone module 99 or the rasterizer 100, and is output to the raster data storage unit 103. In other words, the nozzles for forming the pixels are assigned to the pixels as the area constituting the image to be printed according to the print mode, and the image data after the halftone process is set to each pixel according to the print mode. Are rearranged as print data that can be printed by the nozzles to be formed.

  The print data PD output to the raster data storage unit 103 is temporarily stored in the buffer memory 50, converted into data corresponding to the nozzles, and stored in the image buffer 52. The system controller 54 of the color printer 20 controls the carriage motor drive circuit 61, the carry motor drive circuit 62, the head control unit 63, and the like based on the information of the command COM output from the UI printer interface module 102, and Printing is performed by driving the nozzles of the respective colors provided in the print head 36 based on the data. Here, as the printing mode, for example, a high image quality mode in which dots are recorded using various interlace methods in which the number of nozzles forming one raster line, the conveyance amount of printing paper that is intermittently conveyed, and the like are different, There is a high-speed mode that records dots without using a method. Even in the interlace method, the amount of conveyance carried at one time, the number of carriage movements performed to form one raster line, the number of nozzles used to form one raster line, etc. Even if they are different, the print modes are different.

=== Drive of print head ===
Next, driving of the print head 36 will be described with reference to FIG.
FIG. 8 is a block diagram showing the configuration of the drive signal generator provided in the head control unit 63 (FIG. 6), and FIG. 9 shows the original drive signal ODRV and print signal PRT showing the operation of the drive signal generator. (I) It is a timing chart of drive signal DRV (i). In FIG. 8, the drive signal generation unit 200 includes a plurality of mask circuits 204, an original drive signal generation unit 206, and a drive signal adjustment unit 230. The mask circuit 204 is provided corresponding to a plurality of piezo elements for driving the nozzles n1 to n180 of the print head 36, respectively. In FIG. 8, the number in parentheses at the end of each signal name indicates the number of the nozzle to which the signal is supplied.

  The original drive signal generator 206 generates an original drive signal ODRV that is commonly used for the nozzles n1 to n180. The original drive signal ODRV is a signal that includes two pulses of a first pulse W1 and a second pulse W2 within a carriage movement period for one pixel, and is a reference discharge signal for discharging ink from each nozzle. . That is, all the nozzles of each print head 36 eject ink based on the original drive signal ODRV as the same reference ejection signal. When it is detected by the output of the linear encoder 17 that the carriage 28 has reached a predetermined position, the output of the original drive signal ODRV is started. For this reason, when ink is ejected from each nozzle row of each print head 36 and dot rows are formed at the same target position on the printing paper, the original drive is performed so that the positions of the dot rows in the carriage movement direction match. The output timing of the signal ODRV is adjusted. That is, before this adjustment is made, the initial value is a theoretical value for ejecting ink from the predetermined position to the target position of the printing paper, the relative position between the carriage 28 and the printing paper, and each print head. The interval is set based on the interval in the carriage movement direction, the interval in the carriage movement direction of the nozzle row of each print head, and the set value is stored in the EEPROM. As described above, when ink is ejected to the target position of the printing paper based on the theoretical value set in advance, the position of the dot formed at a position shifted from the position that should be originally formed is: Adjusting so that dots are formed at positions to be formed is referred to as positional deviation adjustment.

  The drive signal adjustment unit 230 can change the position where each dot is formed by shifting the timing of the drive signal waveform shaped by the mask circuit 204 back and forth.

  As shown in FIG. 8, the input serial print signal PRT (i) is input to the mask circuit 204 together with the original drive signal ODRV output from the original drive signal generator 206. The serial print signal PRT (i) is a 2-bit serial signal per pixel, and each bit corresponds to the first pulse W1 and the second pulse W2. The mask circuit 204 is a gate for masking the original drive signal ODRV in accordance with the level of the serial print signal PRT (i). That is, when the serial print signal PRT (i) is 1 level, the mask circuit 204 passes the corresponding pulse of the original drive signal ODRV as it is and supplies it as the drive signal DRV to the piezo element, while the serial print signal PRT (i ) Is 0 level, the corresponding pulse of the original drive signal ODRV is cut off.

As shown in FIG. 9, the original drive signal ODRV generates a first pulse W1 and a second pulse W2 in order in each pixel period T1, T2, and T3. The pixel section has the same meaning as the carriage movement period for one pixel.
As shown in FIG. 9, when the print signal PRT (i) corresponds to 2-bit pixel data “1, 0”, only the first pulse W1 is output in the first half of one pixel interval. Thereby, a small ink droplet is discharged from a nozzle and a small dot (small dot) is formed in a to-be-printed body. When the print signal PRT (i) corresponds to the 2-bit pixel data “0, 1”, only the second pulse W2 is output in the second half of one pixel interval. As a result, medium-sized ink droplets are ejected from the nozzles, and medium-sized dots (medium dots) are formed on the printing medium. When the print signal PRT (i) corresponds to 2-bit pixel data “1, 1”, the first pulse W1 and the second pulse W2 are output in one pixel section. Thereby, a large ink droplet is ejected from the nozzle, and a large dot (large dot) is formed on the printing medium. As described above, the drive signal DRV (i) in one pixel section is shaped to have three different waveforms according to three different values of the print signal PRT (i), and based on these signals. The print head 36 can form dots of three types.

=== Adjustment of positional deviation of dots formed in each print head in the carriage movement direction ===
The color printer 20 described above has eight print heads 36a to 36h, and each print head 36 prints a separate image, and of course, a plurality of print heads 36 are used to print one image. It is also possible to print. When printing one image using a plurality of print heads 36, dots formed by ink ejected from nozzles of different print heads 36 are mixed in the printed image. For this reason, it is necessary to adjust the positions of the dots formed by the ink ejected from the nozzles of the different print heads 36.

  All the nozzles of each print head 36 eject ink based on the original drive signal ODRV output at the same output timing for each print head. For this reason, when ink droplets are ejected to form dots at the same target position on the printing paper P by each print head, the positions of the actually formed dots in the carriage movement direction are matched. The output timing of the original drive signal ODRV for driving each print head 36 is adjusted. At this time, the timing of the original drive signal ODRV to be output to the other print heads is adjusted with one print head 36 among all the print heads 36 that cooperate to form one image. When ink is ejected based on the original drive signal ODRV output at the same output timing for each print head, when printing with achromatic ink and when printing with chromatic ink Since appropriate output timings are different from each other, adjustment of the output timing of the original drive signal ODRV is performed.

  The reference print head 36 (hereinafter referred to as the reference print head) preferably has a relatively stable behavior when the carriage 28 is moved, and the positions of the formed dots do not vary. It is assumed that the print head 36 that is closest to the portion to be operated, that is, the engaging portions S1 and S2 described above in the transport direction. In particular, since the carriage 28 reciprocates in the carriage movement direction, the behavior of the carriage 28 is different due to the difference in how external force acts on the carriage 28 when moving in the forward direction and when moving in the backward direction. Will be different. For this reason, the print head 36 whose behavior is relatively stable in both of the reciprocating movements is the print heads 36d and 36e close to the midpoint 46 of the action line SL that connects the engaging portions S1 and S2, and thus more accurate. In order to make a good adjustment, the reference print heads are designated as print heads 36d and 36e. That is, in the present embodiment, the adjustment is performed based on the output timing of the original drive signal ODRV supplied to the print heads 36 d and 36 e closest to the center of the carriage 28.

  In the dot misalignment adjustment method described below, when one image is printed using two print heads, the dots formed by one print head 36 during the first movement, Ink droplets ejected from the nozzle array of the other print head 36 during the second movement so that the displacement of the dot formation positions formed by the other print head 36 during the second movement is reduced. The discharge timing, that is, the output timing of the original drive signal ODRV is intentionally shifted throughout the second movement. Note that the ejection timing of the ink droplets ejected from the nozzle row of one print head 36 during the first movement may be intentionally shifted throughout the first movement. Here, both the first movement and the second movement may be a movement in the forward direction or a movement in the backward direction in the reciprocating movement of the carriage 28. The first movement and the second movement One of these may be a movement in the forward direction, and the other may be a movement in the backward direction.

  The adjustment of the output timing of the original drive signal ODRV is formed by ejecting ink from the nozzle row N of the one print head 36 with the predetermined position of the print paper P as the target position by moving the carriage 28 in the forward direction. A print pattern 10 composed of dots and dots formed by ejecting ink from the nozzle array N of the other print head 36 is printed, and an optimum output timing is determined based on the printed print pattern 10. . At this time, the relative position of the printing paper P and the carriage 28 in the carriage movement direction is detected based on the output of the linear encoder 17.

  By the way, when an image is actually printed, nozzles for forming dots are allocated to each pixel (region) constituting the image according to a print mode or the like. A print pattern for adjusting the positional deviation of dots in the carriage movement direction is printed in a print mode for actually printing an image. That is, in an actually printed image, ink is ejected from nozzles assigned as nozzles for forming dots in pixels corresponding to regions where dots constituting the print pattern are formed, thereby forming a print pattern.

<Assignment of nozzles that form dots in the area constituting the image to be printed>
As described above, each pixel serving as a region constituting an image to be printed is assigned a nozzle for forming a dot on the pixel. The nozzles assigned to each pixel are set according to the printing mode, that is, the amount of conveyance of the printing paper that is intermittently conveyed, the number of nozzles used to form one raster line, and the like.

  In the present embodiment, for example, in a printing mode (hereinafter, referred to as a two-pass overlap printing mode) in which one raster line is formed by dots formed by ejecting ink from the nozzles of each of the two print heads 36. Next, adjustment of the positional deviation of dots in the carriage movement direction during printing will be described. Here, first, pixels constituting an image to be printed in the two-pass overlap printing mode and nozzles assigned to the pixels will be described. Here, since dots are formed based on image data in an actually printed image, not all pixels in the image area are necessarily filled with dots, but for convenience of explaining the nozzles used here, Assume that an image having dots at all pixels in the image area is printed.

  FIG. 10 is a diagram for explaining the relative positions of the nozzle and the printing paper when printing an image in the two-pass overlap printing mode, and the nozzles assigned to form dots constituting the image to be printed. It is. The left side of FIG. 10 shows the relative positions of the nozzle and the printing paper when printing in the 2-pass overlap printing mode, and the right side shows the nozzles that form the dots of the image printed in the 2-pass overlap printing mode. ing. In FIG. 10, each nozzle row of each print head has seven nozzles, and one nozzle row of the nozzle rows of each print head is arranged linearly along the transport direction. I will explain it. In FIG. 10, the print paper P is stopped and the print head 36 is moved. However, in the actual printing operation, the print paper P is transported and the print paper P and the print paper P are transported. The relative position changes. In the following description, the print head 36 located on the downstream side in the transport direction is called a first print head, and the print head located on the upstream side is called a second print head. The first print head is the third print head 36c from the most downstream side of the color printer 20, and the second print head is the fourth print head 36d from the most downstream side. The nozzles of each print head 36 are referred to as a first nozzle to a seventh nozzle in order from the nozzle located on the downstream side in the transport direction.

  In FIG. 10 and subsequent figures, dots formed by the first print head 36c are indicated by ◯ and ●, and dots formed by the second print head 36d are indicated by Δ and ▲. Further, black symbols (● and ▲) indicate that the carriage 28 is moved in the forward direction, and white symbols (◯ and Δ) indicate that the carriage 28 is moved in the backward direction. The raster line formed on the most downstream side is the first raster line, and FIG. 10 shows up to the 24th raster line. The numbers shown on the right side of each raster line indicate the number of passes in which each dot is formed, the print head number, and the nozzle number. For example, in (3-2-2) of the first raster line, in the pixels of (▲), ink is ejected from the second nozzle of the second print head 36d by the third movement of the carriage 28 (third pass, forward path). It shows that it is formed. In other words, the second nozzle of the second print head 36d in the third pass is assigned to the area indicated by ▲ in the first raster line as a nozzle for forming dots in this area.

  When an image is printed in the two-pass overlap printing mode, the first print head 36d is provided with the first forward movement (first pass) when the carriage 28 reciprocates in the carriage movement direction. Ink is ejected from the nozzle facing the printed paper. In the example of FIG. 10, ink is ejected from the sixth and seventh nozzles of the second print head 36d, and dots are formed in the areas assigned to the respective nozzles. At this time, a plurality of dots (hereinafter referred to as dot rows) constituting the third raster line and the seventh raster line are formed along the carriage movement direction. Each dot included in these dot rows is spaced by one dot.

  Next, the printing paper P is conveyed by 7 dots, the carriage 28 is moved in the backward direction (second pass), and ink is ejected from the fourth to seventh nozzles of the second print head 36d to form dots. A dot is formed in each area allocated to the nozzles. That is, the dot rows constituting the second raster line, the sixth raster line, the tenth raster line, and the fourteenth raster line are formed along the carriage movement direction. In the dot row formed at this time, adjacent dots are separated from each other by one dot. Then, the dot row formed by the movement in the backward direction is formed at a position adjacent to the dot row formed by the movement in the forward direction in the transport direction. In addition, the dots constituting the dot row formed by the movement in the backward direction are located between the dots formed by the movement in the forward direction in the carriage movement direction.

  Next, the printing paper P is again conveyed by 7 dots, the carriage 28 is moved in the forward direction (the third pass), ink is ejected from the second to seventh nozzles, and dots are assigned to the areas allocated to the nozzles. Is formed. That is, the dot rows constituting the first raster line, the fifth raster line, the ninth raster line, the thirteenth raster line, the seventeenth raster line, and the twenty-first raster line are formed along the carriage movement direction. In the dot row formed at this time, adjacent dots in the carriage movement direction are separated from each other by one dot. The dot row formed by the second movement in the forward direction is formed at a position adjacent to the dot row formed by the movement in the backward direction in the transport direction. Further, the dots constituting the dot row formed by the second movement in the forward direction are formed by the movement in the backward direction with each dot formed in the first movement in the carriage direction in the carriage movement direction. It is formed between the dots. As described above, after the printing paper P is conveyed by 7 dots, the carriage 28 is moved and ink is ejected from a predetermined nozzle to form a dot row in which the dot intervals are separated by 1 dot. Repeat the operation. When such a printing operation is executed, as shown in the figure, the dots formed by the movement in the forward direction of the carriage 28 and the dots formed by the movement in the backward direction are detected by the nozzles assigned to the respective areas. As a result, the image is printed.

<Position misalignment adjustment in the carriage movement direction when printing with achromatic ink>
A description will be given of misalignment adjustment of the dot formation position in the carriage movement direction in monochrome printing as achromatic printing in which an image is printed with an achromatic ink, that is, a so-called black ink in the two-pass overlap printing mode. That is, from the second print head 36d as the first ink ejection unit group by the movement in the forward direction as the first movement of the carriage, from the first print head 36c by the movement in the backward direction as the second movement, respectively. One image is formed by the ejected ink droplets.

  FIG. 11 is a diagram for explaining a print pattern used for adjusting the dot formation position in the carriage movement direction when printing an image using black ink in the two-pass overlap printing mode. The left diagram in FIG. 11 shows the image image shown in FIG. 10, the middle diagram shows an example of forming a print pattern in the left image region, and the right diagram shows a 2-dot image. It is the figure which showed the example which forms a printing pattern by a ruled line.

  In FIG. 11, when the carriage 28 moves in the forward direction, the second print head 36d forms dots at five target positions separated by a predetermined interval in the carriage movement direction, and prints vertical ruled lines along the conveyance direction. Similarly, the first print head 36c forms dots at five target positions by moving in the backward direction, and prints vertical ruled lines along the transport direction. At this time, the dots formed by the movement in the forward direction output the original drive signal ODRV at a constant cycle. However, the dots formed by the movement in the backward direction have a predetermined period with respect to the output cycle of the forward path. Output by shifting the timing by the adjustment amount. In other words, the print pattern shown in FIG. 11 has a pair of five vertical ruled lines formed by movement in the forward direction and five vertical ruled lines formed by movement in the backward direction. The five sub-patterns formed in this manner are arranged at intervals in the carriage movement direction. These five sub-patterns are configured so that the output timing of the original drive signal ODRV that is output to form dots by movement in the backward direction is sequentially different by a predetermined adjustment amount with respect to the forward direction. The relative positions of the vertical ruled lines formed by the movement and the vertical ruled lines formed by the movement in the backward direction are different. That is, with respect to the vertical ruled line formed by the second print head 36d by the movement in the forward path direction, the position of the vertical ruled line formed by the first print head 36c by the movement in the backward path is made different in the carriage movement direction. A print pattern is formed. Here, as described above, the vertical ruled line formed by the second print head 36d is used as a reference. As described above, the first print head 36c and the second print head 36d have the second print head 36d more This is because it is located at the center of the engaging portions S1, S2 where the traction force acts, that is, on the side close to the midpoint 46 of the action line SL connecting the engaging portions S1, S2, and vibration during movement of the carriage 28 is small.

  FIG. 12 is a diagram for explaining a method of forming a print pattern for adjusting the dot formation position when printing with achromatic ink.

  The printing method of the print pattern 10 is as follows. First, as shown in FIG. 10, the printing paper P is intermittently set in advance by a preset conveyance amount (predetermined conveyance amount: 7 dots) as in the case of actually printing an image. Then, the printing paper P is conveyed twice and arranged so that the leading edge of the printing paper P is positioned at the same position as when the image is actually printed (S101). At this time, the distance of 14 dots at a time is not conveyed because it is the same as the conveying method in the case of actually printing an image. That is, even if the transport motor 31 is driven in the same manner, if the transport amount at one time is large, an error is likely to occur, and the smaller the transport amount at one time tends to be transported with high accuracy. The transport method is the same as when printing an image. As described above, the dot formation position can be adjusted more accurately by combining the operation for actually printing an image with the operation for printing the print pattern 10. Further, at this time, when the roll paper is disposed over the entire area facing the carriage, this operation is not necessary. Here, the printing paper P on which the printing pattern 10 is printed is preferably a printing paper used when an image is actually printed. In this example, since the two-pass overlap printing mode is a printing mode for printing a relatively high-quality image, for example, photographic paper or the like is used as the printing paper.

  When the printing paper P is conveyed, the first movement (first pass) of the carriage 28 is executed, and ink is ejected from the fifth, sixth, and seventh nozzles of the second print head 36d at a predetermined timing. To form dots (S102). At this time, the relative position between the print paper in the first movement of the carriage 28 and the print head when printing the print pattern is the same as the print paper in the third movement (third pass) when actually printing the image, The relative position to the print head.

  Next, the printing paper P is intermittently transported twice by 7 dots (S103). At the same time as the printing paper P is conveyed, the carriage 28 is moved in the backward direction without ejecting ink from all the nozzles, and the carriage 28 is arranged at the start position in the movement in the forward direction. Thereafter, while moving the carriage 28 in the forward direction, ink is ejected from the second and third nozzles of the second print head 36d at predetermined timings to form dots (S104). At this time, the relative position between the print paper in the second movement of the carriage 28 when printing the print pattern and the print head is the print paper in the fifth movement (fifth pass) when actually printing the image. And the relative position to the print head. As the carriage 28 moves in the forward direction, five vertical ruled lines are formed at intervals in the carriage movement direction by the second print head 36d.

  Next, the printing paper P is moved by a distance of 7 dots by a preset conveyance amount (S105). Thereafter, while moving the carriage 28 in the backward direction, ink is ejected from the fifth and sixth nozzles of the first print head 36c to form dots (S106). At this time, the target position is set so that the relative position between the dot formed by the first print head 36c and the dot formed by the second print head 36d in the forward movement is slightly different for each sub-pattern. Is set and ink is ejected. That is, in each sub-pattern, the dots formed by the first print head 36c and the dots formed by the second print head 36d by movement in the forward direction are formed at the same position in the carriage movement direction. It is formed with a set timing and a timing set so as to be formed at a position different from the timing by a predetermined adjustment amount. For example, when each of the adjustment amounts that can be adjusted in five steps can be set with five adjustment values from “−2” to “+2”, the leftmost sub-pattern is formed by the first print head 36c. The ink is ejected at a timing when the dots formed by the second print head 36d by the movement in the forward direction are shifted by the adjustment amount indicated by the adjustment value “−2”. Is done. In the center sub-pattern, the dot formed by the first print head 36c and the dot formed by the second print head 36d by movement in the forward direction are indicated by an adjustment value “0”. Ink is ejected at an amount, that is, at a timing when it is formed at a position where there is no deviation. At this time, for example, if the adjustment amount is changed by one step, the position of the dot formed by the first print head 36c with respect to the dot formed by the second print head 36d by the movement in the forward direction is the carriage movement. It is set to change by the minimum controllable distance in the direction.

  Next, the printing paper P is conveyed twice intermittently by 7 dots (S107). At the same time as the printing paper P is conveyed, the carriage 28 is moved in the forward direction without ejecting ink from all the nozzles, and the carriage 28 is disposed at the start position in the movement in the backward direction. Thereafter, while moving the carriage 28 in the backward direction, ink is ejected from the first, second, and third nozzles of the first print head 36c at timings sequentially shifted from the predetermined timing to form dots. (S108). At this time, the relative position between the print paper in the fourth movement of the carriage 28 when printing the print pattern and the print head is the print paper in the eighth movement (8th pass) when actually printing the image. And the relative position to the print head. As the carriage 28 moves in the forward direction, five vertical ruled lines are formed at intervals in the carriage movement direction by the second print head.

  In the print pattern shown in the center diagram of FIG. 11, in the sub-pattern located in the center printed with the adjustment value “0”, the vertical ruled line formed by the movement in the forward direction and the movement in the return direction Since the formed vertical ruled lines are printed in one straight line, an adjustment value “0” is set when printing an image using black ink in the two-pass overlap printing mode.

  In the present embodiment, a ruled line having a carriage movement direction of 1 dot has been described as a vertical ruled line. However, as shown in the diagram on the right side of FIG. 11, a ruled line formed by a 2-dot ruled line or a larger number of dots is used. It is good.

<Adjusting the positional deviation of dots in the carriage movement direction when printing with chromatic ink>
In color printing as chromatic printing using chromatic ink, an image such as a natural image is mainly printed. For this reason, it is necessary to adjust the positions of the dots formed by the inks of a plurality of colors ejected from the print head. However, when the output timing of the original drive signal ODRV is the same for each print head, it is difficult to adjust so that the positions of all the dots formed by a plurality of colors of ink are aligned. For this reason, in the case of color printing, a carriage of dots formed by cyan ink and light magenta ink mainly constituting a low gradation portion of an image that is particularly susceptible to image quality such as a natural image, that is, a so-called highlight portion The position in the movement direction is adjusted with respect to the position of the dot formed by the reference print head 36. Also, dots formed in highlight portions that tend to affect image quality in natural images and the like are mainly small dots. As described above, in the color printer of this embodiment, since the timing for forming the small dots and the medium dots is different, the positions where the dots are formed are slightly different depending on the size of the dots to be formed. For this reason, the print pattern used for color printing is formed with small dots, and adjustments more suitable for the image are performed.

  In the case of color printing, it is assumed that printing is performed in the 2-pass overlap printing mode. Here, of the movements of the carriage 28 in the forward direction and the backward direction, the forward direction is set as a specific direction, and the light cyan color formed by the second print head 36d by the movement in the forward direction as the first movement of the carriage 28 is set. The amount of positional deviation in the carriage movement direction between the small dot and the light cyan small dot formed by the first print head 36c by the movement in the forward direction as the second movement at a timing different from the first movement, and the carriage Light magenta small dots formed by the second print head 36d in the forward movement as the first movement 28 and the first print head 36c in the forward movement as the second movement at different timings. The first print head 3 so that the amount of positional deviation in the carriage movement direction with the light magenta small dots formed by Adjusting the output timing of the original drive signal ODRV of c.

  FIG. 13 is a diagram for explaining a print pattern used for dot misalignment adjustment in the carriage movement direction when an image is printed using chromatic ink in the two-pass overlap printing mode. The print pattern shown in FIG. 13 has ten patches arranged in five rows in the left-right direction and in two rows in the up-down direction. The upper five patches are formed with light cyan ink, and the lower five patches are formed with light magenta. The two patches arranged above and below are paired and formed with the same adjustment value. Here, when printing a print pattern, the left-right direction corresponds to the carriage movement direction, and the up-down direction corresponds to the transport direction.

  FIG. 14 is a diagram for explaining a method of forming a print pattern used for adjusting the dot formation position in the carriage movement direction when printing an image using chromatic color ink. FIG. 14 shows the forming method by paying attention to only one sub-pattern composed of a pair of patches arranged one above the other among the print patterns having ten patches described above. In FIG. 14, squares arranged in two rows and five rows indicate patch formation regions, and a pair of upper and lower patches indicate a patch formation method in time series in order from the left. That is, the dots formed in the fifth pass from the dots formed in the first pass from left to right are shown in time series. Here, the patch formation area corresponds to an area of 11 pixels in the upper left corner of the image image shown in FIG. 10, and ink is ejected from nozzles assigned as nozzles for forming dots in this area. A print pattern is to be formed.

  In this print pattern, for example, patches of 11 pixels vertically and horizontally are ejected by light cyan ink by the second print head 36d by movement of the carriage 28 in the forward direction to form small dots in the assigned region, and the forward direction Printing is performed by forming small dots in an area to which light cyan dots are allocated by the first print head 36c by movement in the forward direction at a timing different from that of the movement of. At this time, similarly to the adjustment of the output timing when printing with the achromatic ink described above, a plurality of small dots are printed at a predetermined target position by the second print head 36d, and the first print head 36c A plurality of patches are printed by forming a plurality of small dots by sequentially changing the discharge timing by minute time. A plurality of patches are printed in the same manner with light magenta ink. Also in this embodiment, the adjustment values are set in five stages, and five patches are formed for each of light cyan ink and light magenta ink. Hereinafter, the points common to the adjustment of the output timing at the time of printing with the achromatic ink described above will be described with the detailed description omitted.

In the printing method of the printing pattern 10, as shown in FIG. 10, the printing paper P is first transported to a position where the leading edge of the printing paper P is located sufficiently downstream from the sixth nozzle of the second printing head.
When the printing paper P is conveyed, the first movement (first pass) of the carriage 28 is executed, and light cyan ink is applied at a predetermined timing from the sixth and seventh nozzles of the light cyan nozzle row of the second print head 36d. By discharging, small dots are formed (FIG. 14 (1)). Although only one patch area is shown in FIG. 14, small dots are formed in five areas at intervals in the carriage movement direction in order to form five patches.

  Next, the printing paper P is intermittently conveyed twice by 7 dots twice, and the carriage 28 is moved in the backward direction without discharging ink from all the nozzles, and the carriage 28 is moved to the start position in the movement in the forward direction. Deploy. Thereafter, while moving the carriage 28 in the forward direction (second pass), the light cyan ink is supplied from the second, third, and fourth nozzles of the light cyan nozzle row of the second print head 36d at a predetermined timing, and the second Light magenta ink is ejected from the fifth, sixth, and seventh nozzles of the light magenta nozzle row of the print head 36d at predetermined timings to form small dots (FIG. 14 (2)). At this time, the relative position between the print paper in the second movement of the carriage 28 when printing the print pattern and the print head is the print paper in the third movement (third pass) when actually printing the image. And the relative position to the print head.

  Further, the printing paper P is intermittently conveyed twice by 7 dots twice, and the carriage 28 is moved in the backward direction without ejecting ink from all the nozzles, and the carriage 28 is moved to the start position in the movement in the forward direction. Deploy. Thereafter, while moving the carriage 28 in the forward direction (third pass), the second, third, and fourth of the first nozzle of the light cyan nozzle row of the second print head 36d and the light magenta nozzle row of the second print head 36d. Light magenta ink is ejected from the nozzles at a predetermined timing to form small dots (FIG. 14 (3)). Further, light cyan ink is ejected from the sixth and seventh nozzles of the light cyan nozzle row of the first print head 36c (FIG. 14 (3)). At this time, the light cyan ink is discharged from the first print head 36c at the timing of the light cyan dots formed by the first print head 36c and the light cyan dots formed by the second print head 36d in five patches. In the carriage movement direction, different timings are set based on the adjustment amounts indicated by the five levels of adjustment values. The relative position of the print paper and the print head in the third movement of the carriage 28 when printing this print pattern is the same as the print paper in the fifth movement (fifth pass) when actually printing the image. The relative position to the print head.

  Next, the printing paper P is intermittently conveyed twice by 7 dots twice, and the carriage 28 is moved in the backward direction without discharging ink from all the nozzles, and the carriage 28 is moved to the start position in the movement in the forward direction. Deploy. Thereafter, while moving the carriage 28 in the forward direction (fourth pass), the second, third, and fourth nozzles of the light cyan nozzle row of the first print head 36c and the fifth of the light magenta nozzle row of the first print head 36c. , The sixth and seventh nozzles are ejected to form small dots (FIG. 14 (4)). Also at this time, the timing at which the light cyan ink is ejected from the first print head 36c is the same as the small dots formed by the first print head 36c and the small dots formed by the second print head 36d in five patches. However, the timings are set to be different from each other based on the adjustment values in five steps in the carriage movement direction. The relative position of the print paper and the print head in the fourth movement of the carriage 28 when printing this print pattern is the same as the print paper in the seventh movement (the seventh pass) when actually printing an image, The relative position to the print head.

  Further, the printing paper P is intermittently conveyed twice by 7 dots, and the carriage 28 is moved in the backward direction without ejecting ink from all the nozzles, and the carriage 28 is disposed at the start position in the movement in the forward direction. To do. Thereafter, while moving the carriage 28 in the forward direction (fifth pass), the first nozzle of the light cyan nozzle row of the first print head 36c and the second, third, and fourth of the light magenta nozzle row of the first print head 36c. Ink is ejected from the nozzles to form small dots (FIG. 14 (5)). Also at this time, the timing at which ink is ejected from the first print head 36c is such that the small dots formed by the first print head 36c and the small dots formed by the second print head 36d in five patches. In the carriage movement direction, different timings are set on the basis of the adjustment values in five steps. The relative position between the print paper in the fifth movement of the carriage 28 when printing this print pattern and the print head is the print paper in the ninth movement (9th pass) when actually printing the image, The relative position to the print head.

  In this manner, a print pattern having five light cyan patches and five light magenta patches is formed. For each of the five patches of each color, the leftmost patch is formed based on the adjustment value “−2”, the rightmost patch is formed based on the adjustment value “+2”, and the adjustment values sequentially change. Are arranged to be. When the small dots formed by the first print head 36c and the second print head 36d are arranged at appropriate positions, the dots are arranged almost evenly in the patch area. If it is not appropriate, the small dots formed by one of the print heads 36 are printed close to or overlapping with the dots formed by the other print head 36. That is, when the small dots formed by the first print head 36c and the second print head 36d are not arranged at appropriate positions, the margin in the patch area increases and the patch density is increased. When the dot is low and the dots are arranged at appropriate positions, the density of the patch is high. For this reason, the timing at which ink is ejected from the first print head is set to an adjustment value when the patch having the highest density among the five patches is printed.

  In the case of the present embodiment, since five patches are printed with two colors of light magenta and light cyan, respectively, the average value of adjustment values when a patch having the highest density of each color patch is formed. Is the timing at which ink is ejected from the first print head 36c. In the example of FIG. 13, the density of the patch printed with the second adjustment value “−1” from the left is high in the light cyan patch, and the second adjustment value “+1” from the right in the light magenta patch. The density of the printed patch is high. For this reason, the average value “0” is set as an adjustment value when the color printer 20 prints an image using chromatic color ink in the two-pass overlap printing mode.

  Incidentally, the patch having the highest density may be selected by the user or the like and input to the color printer 20, but for example, it is provided on the carriage 28 of the color printer 20 and used for detecting the presence or absence of paper. The reflection-type optical sensor 13 reads the patch, and the system controller 54 may execute the patch based on the read result.

  In the above embodiment, the printing pattern when printing with black ink is a printing pattern for adjusting the positional deviation of dots when the carriage is reciprocated, and the printing pattern when printing with chromatic ink is used as the printing pattern. Although described as a print pattern for adjusting the positional deviation of dots when moving in one direction, the present invention is not limited to this. Further, a print pattern having ten patches may be used as a misalignment adjustment print pattern between dots formed by movement in the forward direction and dots formed by movement in the backward direction. A print pattern having ruled lines may be used as a print pattern for adjusting the positional deviation between dots formed during the movement of the dots.

  According to the color printer 20 of the present embodiment, the print pattern for executing the misregistration adjustment for adjusting the misregistration of the dot formation position in the carriage movement direction becomes a reference in the first movement of the print head 36. It is formed by ejecting ink droplets from the nozzles of the second print head 36d and ejecting ink droplets from the nozzles of the first print head 36c to be adjusted during the second movement. For this reason, when the misalignment adjustment is executed based on the printed print pattern, the movement of dots formed when the carriage 28 moves differently between the first print head 36c and the second print head 36d. It is possible to adjust the positional deviation in the direction. Also, the print pattern is printed by ejecting ink to the areas assigned to the respective nozzles as in the case of actually printing one image by the first and second print heads. For this reason, when the misregistration adjustment is executed based on the print pattern, more appropriate adjustment is executed when an image is actually printed, and more appropriate adjustment is executed. It is possible to print a good image using the print head 36.

  In addition, the second print head 36d serving as a reference is a print head 36 other than the print head 36 that is most susceptible to vibration due to movement. Little drowning is formed. For this reason, the dots formed by the first print head 36c can be formed at a position close to the target position by performing positional deviation adjustment with reference to the dots formed by the second print head 36d. Is possible.

  In particular, in the present embodiment, the second print is located on the side closer to the midpoint 46 of the action line SL that connects the engagement portions S1 and S2 as the two portions where the external force acts on the reference print head 36. The head 36d is used. The midpoint 46 of the action line SL that connects the two engaging portions S1 and S2 to which an external force acts is less susceptible to vibration in the carriage 28 and has the most stable behavior during movement. It is possible to include dots formed by the second print head 36d that discharges ink in the most stable state. For this reason, the position of the dot formed by the first print head 36c is more appropriately determined by using the position of the dot formed by the second print head 36d that discharges ink in the most stable state as a reference. It is possible to adjust the position. For this reason, even if the dots formed by any print head 36 are formed at a more appropriate position, it is possible to print a good image using a plurality of print heads 36. is there.

  Further, since the dot formation position is adjusted by adjusting the timing of the original drive signal ODRV in the plurality of print heads 36, the dots formed by the first print head 36c and the second print head 36d are formed. It is possible to easily and accurately execute the positional deviation adjustment of the dots.

  In addition, each of the plurality of sub-patterns included in the print pattern is formed based on an adjustment value in which the shift amount of the dot formation position differs for each sub-pattern. For this reason, it is possible to easily print a good image by extracting a well-printed sub-pattern, adjusting the adjustment value when the extracted sub-pattern is formed, and printing the image. It is.

  By the way, when performing monochrome printing and when performing color printing, not only the ink to be used but also the ink discharge section to be used is different. For this reason, each ink color dot is formed at a different position. For this reason, when performing monochrome printing and when performing color printing, different misalignment adjustments are possible, so that appropriate adjustments can be made between monochrome printing and color printing. It is possible to print a good image.

  In particular, since the printing pattern for misregistration adjustment during color printing is printed with light magenta and light cyan inks among a plurality of color inks, it is shorter than printing with inks of all colors. It is possible to print a print pattern at a time and set an adjustment value. That is, when color printing is performed, a printing pattern is formed with the ink of the color that should be most adjusted, and the adjustment value is set, so that the time spent for setting the adjustment value is shortened and good Color images can be printed. Furthermore, in color printing, print patterns are printed with light magenta and light cyan, which are mainly used for highlight areas that tend to affect the image quality, and with small dots mainly used for highlight areas. Since the positional deviation adjustment is executed based on the printed print pattern, it is possible to appropriately adjust the positions in the moving direction of the dots formed in the highlight portion by the plurality of print heads 36. . Therefore, it is possible to print a better color image. In addition, since the print pattern is printed with only small dots, it is possible to print the print pattern in a shorter time than when printing with dots of all sizes and set the adjustment value.

  In this embodiment, an example in which a print pattern is formed with small dots has been described. However, the present invention is not limited to this, and may be medium dots or large dots, and large, medium, or small dots may be used. The print pattern may be printed in a distributed manner in the patch area. Further, the adjustment value may be obtained from five patches having different adjustment values for large dots, medium dots, and small dots. FIG. 15 is a diagram for explaining an adjustment value setting method when a print pattern is formed with each dot size. In this case, first, a print pattern of five rows and two stages as described above is formed at each dot size (S201). Next, the patch with the highest density is extracted from the five patches of light cyan and light magenta formed with dots of each size (S202). An average value of adjustment values when the extracted light cyan and light magenta patches are formed is determined for each dot size (S203). The average value of the obtained average values for each dot size is obtained (S204), and the obtained average value of the previous dot size is stored as an adjustment value for adjusting the positional deviation of the dot formation position in the carriage movement direction when performing color printing (S204). S205).

  In this case, the dot formation position is adjusted for dots of any size. For this reason, compared with the case where the dot formation position is adjusted only for dots of a predetermined size based on a print pattern formed with dots of any one of the three types of dots, each size It is possible to prevent the dot formation position from significantly deviating from the target position. For this reason, it is possible to print all the images formed with dots of each size relatively well.

=== Other Embodiments ===
The present invention is not limited to the above-described embodiment, and can be implemented in various modes without departing from the gist thereof. For example, the following modifications are possible.

(1) In the above embodiment, a part of the configuration realized by hardware may be replaced by software, and conversely, a part of the configuration realized by software may be replaced by hardware. Also good.
(2) The present invention is generally applicable to printing apparatuses that eject ink droplets, and can be applied to various printing apparatuses other than color inkjet printers. For example, the present invention can be applied to an ink jet facsimile machine and a copying machine.
(3) In the above embodiment, the example in which the printing system is configured by the color printer 20, the computer 90, the display device, the input device, the drive device, and the like has been described, but the present invention is not limited to this. For example, the printing system may be configured by the computer 90 and the color printer 20, and the printing system may not include any of the display device, the input device, and the drive device.

  For example, the color printer 20 may have a part of the functions or mechanisms of the computer 90, the display device, the input device, and the drive device. As an example, the color printer 20 includes an image processing unit that performs image processing, a display unit that performs various displays, and a recording medium attachment / detachment unit for attaching / detaching a recording medium that records image data captured by a digital camera or the like. It is good also as a structure which has.

  In addition, the computer program for controlling the printer in the above-described embodiment is stored in the memory of the printer controller, and the printer controller executes the computer program to achieve the printer operation of the above-described embodiment. Good.

  The printing system realized in this way is a system superior to the conventional system as a whole system.

1 is a perspective view illustrating an example of a configuration of a color printer according to the present invention. An explanatory view schematically showing a configuration of the linear encoder 17. FIG. 3A is a timing chart showing waveforms of two output signals of the linear encoder 17 during forward rotation of the carriage motor, and FIG. 3B shows waveforms of two output signals of the linear encoder 17 during reverse rotation of the carriage motor. Timing chart. Explanatory drawing for demonstrating the arrangement | sequence of the nozzle which a print head has. The figure which shows the positional relationship of arrangement | positioning of several adjacent print heads, and the nozzle row which these print heads have. 1 is a block diagram illustrating a configuration of a printing system including a color printer. The block diagram which shows the structure of an image processing unit. The block diagram which shows the structure of the drive signal generation | occurrence | production part provided in the head control unit (FIG. 6). 4 is a timing chart of an original drive signal ODRV, a print signal PRT (i), and a drive signal DRV (i) showing operations of the drive signal generator. The figure for demonstrating the nozzle allocated when forming the dot which comprises the relative position of the nozzle and printing paper at the time of printing an image in 2-pass overlap printing mode, and the image to be printed. FIG. 6 is a diagram for explaining a print pattern used for adjusting a dot formation position in a carriage movement direction when an image is printed using black ink in a two-pass overlap printing mode. The figure for demonstrating the method of forming the printing pattern for adjusting the formation position of the dot at the time of printing with achromatic ink. FIG. 6 is a diagram for explaining a print pattern used for adjusting a dot formation position in a carriage movement direction when an image is printed using chromatic color ink in a two-pass overlap printing mode. The figure for demonstrating the formation method of the printing pattern used for adjustment of the dot formation position in a carriage movement direction, when printing an image using chromatic color ink. The figure for demonstrating the setting method of the adjustment value at the time of forming a printing pattern by each dot size.

Explanation of symbols

3 printing section, 5 printing paper transport section, 10 printing pattern, 13 reflective optical sensor, 16 rotary encoder, 17 linear encoder, 17a diode, 17b collimator lens, 17c detection processing section, 17d photodiode, 17e signal processing Circuit, 17 fA comparator, 17 fB comparator, 19 linear encoder code plate, 20 color printer, 21 CRT, 24 paper transport roller, 26 platen, 27 holder, 27 a shaft body, 27 b disk, 28 carriage, 29 clamping roller, 30 carriage Motor, 31 transport motor, 32 traction belt, 34 guide rail, 341 lower guide rail, 342 upper guide rail, 35 roll paper holder, 36 print head, 36a-36h print head, 37 Roll paper transport unit, 38 Image processing unit, 40 Drive gear, 41 Relay gear, 44 Pulley, 45 Pulley, 46 Midpoint of action line, 50 Buffer memory, 52 Image buffer, 54 System controller, 56 Main memory, 58 EEPROM, 61 Carriage motor drive circuit, 62 Carriage motor drive circuit, 63 Head control unit, 67 Ink tank, 90 Computer, 91 Video driver, 95 Application program, 97 Resolution conversion module, 98 Color conversion module, 99 Halftone module, 100 Rasterizer, 101 User Interface Display Module, 102 UI Printer Interface Module, 103 Raster Data Storage Unit, 200 Drive Signal Generation Unit, 204 Mask Circuit 206 Original drive signal generation unit, 230 Drive signal adjustment unit, Nc cyan nozzle row, Nk black nozzle row, Nlc light cyan nozzle row, Nlm light magenta nozzle row, Nm magenta nozzle row, Ny yellow nozzle row, P printing paper, P1 P11 sub-pattern, T1 pixel interval, W1 pulse, W2 pulse, n nozzle, LUT lookup table, ODRV original drive signal

Claims (19)

(A) an ink ejection unit group unit having at least two ink ejection units each including a plurality of ink ejection units for ejecting ink droplets to form dots on a print medium;
(B) a moving unit for moving the ink discharge unit group unit along a predetermined moving direction;
(C) It is possible to cause one or more ink ejection units to print one image by ejecting ink from each of the ink ejection units in an area allocated to each of the ink ejection units. A control unit,
Adjusting the deviation of the dot formation position in the movement direction between the dot formed by the first movement of the ink discharge unit group unit and the dot formed by the second movement of the ink discharge unit group unit A print pattern for performing the positional deviation adjustment is applied to an area allocated to the ink discharge section provided in the first ink discharge section group during the first movement of the ink discharge section group unit. Ink droplets are ejected from a part, and the ink ejection part is arranged in an area allocated to an ink ejection part provided in a second ink ejection part group different from the first ink ejection part group during the second movement. A control unit capable of printing by ejecting ink droplets from,
A printing apparatus having (d). The printing apparatus according to claim 1,
The first ink ejection unit group is the ink ejection unit group other than the ink ejection unit group that is most susceptible to vibration caused by the movement of the ink ejection unit group unit during the first movement. apparatus. The printing apparatus according to claim 1 or 2,
The printing apparatus according to claim 1, wherein the first ink discharge unit group is an ink discharge unit group that is less susceptible to vibration due to movement of the ink discharge unit group unit than the second ink discharge unit group. The printing apparatus according to any one of claims 1 to 3,
The ink discharge unit group unit is moved by an external force, and the first ink discharge unit group is other than the ink discharge unit group existing at a position farthest from the site where the external force acts in a direction intersecting the moving direction. A printing apparatus characterized by being an ink ejection unit group. The printing apparatus according to claim 4,
The printing apparatus according to claim 1, wherein the first ink discharge unit group is located closer to a portion where the external force acts than the second ink discharge unit in a direction intersecting the moving direction. The printing apparatus according to claim 4 or 5,
There are two places where the external force acts,
The printing apparatus according to claim 1, wherein the first ink discharge unit group is located closer to the center of the two portions where the external force acts than the second ink discharge unit. The printing apparatus according to any one of claims 1 to 6,
Each of the ink ejection unit groups is driven based on a single reference ejection signal for ejecting ink from the ink ejection unit,
The positional deviation adjustment is performed by adjusting the timing of the reference ejection signal of the second ink ejection section group with reference to the timing of the reference ejection signal of the first ink ejection section group. Printing device. The printing apparatus according to any one of claims 1 to 7,
The ink discharge unit group unit can reciprocate, the first movement is a movement in the forward direction of the ink discharge unit group unit, and the second movement is a return direction of the ink discharge unit group unit. A printing apparatus, characterized in that The printing apparatus according to any one of claims 1 to 7,
The ink discharge unit group unit is capable of reciprocating, the first movement is movement of the ink discharge unit group unit in a specific direction in the forward or backward direction, and the second movement is the first movement. The printing apparatus is a movement in the specific direction that is executed at a timing different from the movement of the printing apparatus. The printing apparatus according to any one of claims 1 to 9,
The printing pattern has a plurality of sub-patterns formed by ink ejected from the first ink ejection unit group and the second ink ejection unit group, respectively.
A plurality of adjustment amounts for performing the positional deviation adjustment;
The amount of deviation of the dot formation position between the dots formed by the first ink ejection unit group and the dots formed by the second ink ejection unit group in each sub-pattern differs for each sub-pattern. A printing apparatus characterized by an adjustment amount. The printing apparatus according to any one of claims 1 to 10,
The first ink ejection unit group and the second ejection unit group each have an achromatic ink ejection unit that ejects achromatic ink, and a chromatic ink ejection unit that ejects chromatic ink,
The misregistration can be adjusted differently when the achromatic color is ejected and the achromatic color printing is performed and when the chromatic color ink is ejected and the chromatic color printing is performed. Printing device. The printing apparatus according to claim 11.
Each of the ink ejection unit groups has a plurality of the chromatic color ink ejection units, and each chromatic color ink ejection unit group ejects different colors of ink for each color,
When forming the dots using the chromatic color ink, when the positional deviation adjustment is performed, the print pattern is printed with any one of the plurality of chromatic color inks. A printing apparatus characterized by the above. The printing apparatus according to claim 12, wherein
The printing apparatus is characterized in that the printing pattern is printed with ink of a color mainly used when printing a low gradation portion of an image among the plurality of chromatic color inks. The printing apparatus according to any one of claims 1 to 13,
The ink ejection unit can form a plurality of types of dots having different sizes,
The printing apparatus is characterized in that the printing pattern is formed by dots of any size among the plurality of types of dots. The printing apparatus according to any one of claims 1 to 14,
The ink ejection unit can form a plurality of types of dots having different sizes,
In the misregistration adjustment, an average value of the adjustment amounts acquired based on the print patterns respectively formed by the plurality of types of dots is used as an adjustment amount for executing the misregistration adjustment. Printing device to do.   (A) an ink ejection unit group unit having at least two ink ejection units each having a chromatic color ink ejection unit for ejecting chromatic color ink to form a plurality of types of dots having different sizes on a print medium; (B) a moving part for reciprocating along a predetermined moving direction by an external force acting on two positions of the ink discharging part group unit; and (c) a single part for discharging ink from the ink discharging part. Ink is ejected from each of the ink ejecting sections to an area allocated to each of the ink ejecting sections driven based on the reference ejection signal, and one image is formed by the at least two ink ejecting section groups. A control unit that enables printing, dots formed by movement of the ink discharge unit group unit in the forward direction, and movement of the ink discharge unit group unit in the return direction The second ink, which is different from the first ink ejection unit group, with reference to the timing of the reference ejection signal of the first ink ejection unit group with respect to the deviation of the dot formation position in the movement direction from the dots formed by A printing pattern for performing misalignment adjustment to be performed when performing chromatic printing by ejecting the chromatic color ink by adjusting the timing of the reference ejection signal of the ejection unit group based on the adjustment amount Is provided in the first ink discharge unit group located on the side closer to the center of the two portions to which the external force acts when the ink discharge unit group unit moves in the forward direction. A plurality of sub-patterns are formed by ejecting ink droplets from the ink ejection section in an area allocated to an ink ejection section that ejects ink of a color mainly used when printing a toned portion; When moving in the return path direction, a plurality of sub-patterns are formed for each sub-pattern by causing ink droplets to be ejected from the ink-ejection unit to areas allocated to the ink-ejection units provided in the second ink ejection unit group. A controller capable of performing printing with the plurality of types of dots with different adjustment amounts, and performing the positional deviation adjustment with an average value of the adjustment amounts acquired based on the printed sub-pattern; , (D). (A) an ink ejection unit group unit having at least two ink ejection units each including a plurality of ink ejection units for ejecting ink droplets to form dots on a print medium;
(B) a moving unit for moving the ink discharge unit group unit along a predetermined moving direction;
(C) It is possible to cause one or more ink ejection units to print one image by ejecting ink from each of the ink ejection units in an area allocated to each of the ink ejection units. A control unit;
A printing apparatus having (d),
Adjusting the deviation of the dot formation position in the movement direction between the dot formed by the first movement of the ink discharge unit group unit and the dot formed by the second movement of the ink discharge unit group unit A print pattern for performing the positional deviation adjustment is applied to an area allocated to the ink discharge section provided in the first ink discharge section group during the first movement of the ink discharge section group unit. Ink droplets are ejected from a part, and the ink ejection part is arranged in an area allocated to an ink ejection part provided in a second ink ejection part group different from the first ink ejection part group during the second movement. A computer program for realizing a function of printing by ejecting ink droplets from a printer. (A) a computer body;
(B) a printing apparatus connected to the computer body and having the following (a) to (c):
(A) an ink ejection unit group unit having at least two ink ejection units each including a plurality of ink ejection units for ejecting ink droplets to form dots on a print medium;
(B) a moving unit for moving the ink discharge unit group unit along a predetermined moving direction;
(C) It is possible to cause one or more ink ejection units to print one image by ejecting ink from each of the ink ejection units in an area allocated to each of the ink ejection units. A control unit,
Adjusting the deviation of the dot formation position in the movement direction between the dot formed by the first movement of the ink discharge unit group unit and the dot formed by the second movement of the ink discharge unit group unit A print pattern for performing the positional deviation adjustment is applied to an area allocated to the ink discharge section provided in the first ink discharge section group during the first movement of the ink discharge section group unit. Ink droplets are ejected from a part, and the ink ejection part is arranged in an area allocated to an ink ejection part provided in a second ink ejection part group different from the first ink ejection part group during the second movement. A control unit capable of printing by ejecting ink droplets from,
A printing system comprising (C). A first movement along a predetermined movement direction of an ink ejection unit group unit having at least two ink ejection unit groups each having a plurality of ink ejection units for ejecting ink droplets to form dots on a print medium. When the second movement along the predetermined movement direction, the ink droplets are ejected from the ink ejection unit to the area allocated to the ink ejection unit provided in the first ink ejection unit group. Printing a print pattern by causing ink droplets to be ejected from the ink ejection section in an area allocated to an ink ejection section provided in a second ink ejection section group different from the first ink ejection section group;
Based on the printed print pattern, the dots formed by the first movement of the ink discharge unit group unit and the dots formed by the second movement of the ink discharge unit group unit, The deviation of the dot formation position in the moving direction is adjusted, and in each of the at least two ink ejection unit groups, ink is ejected from each of the ink ejection units to the area allocated to each of the ink ejection units. Printing an image;
A printing method characterized by comprising:

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