JP2010105289A - Fluid jet apparatus and fluid jet method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress an attachment error when a plurality of nozzle arrays are attached to an apparatus, and to restrict uneven application of a fluid possibly caused at a joint between the nozzle arrays because the fluid jetted from the nozzles sometimes hits curving on a medium. <P>SOLUTION: A dot train in which a plurality of dots are arranged in a direction which intersects a predetermined direction is formed by overlapping nozzles of a first nozzle array and a second nozzle array determined on the basis of first data. A dot train in which a plurality of dots are arranged in the direction which intersects the predetermined direction is formed by overlapping nozzles of a third nozzle array and a fourth nozzle array determined on the basis of second data different from the first data. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a fluid ejecting apparatus and a fluid ejecting method.

  As an example of a fluid ejecting apparatus, an ink jet printer that ejects ink is known. In an inkjet printer, a plurality of nozzle rows are arranged side by side in order to increase the area that can be printed at once. When printing by arranging a plurality of nozzle rows, if the ink ejection characteristics are different for each nozzle row, the image quality of the images formed by each nozzle row will be different, and the image quality at the joint between the nozzle rows will be different. The difference is noticeable.

Therefore, it is known that the difference in image quality is made inconspicuous by arranging the nozzle rows and the nozzle rows in an overlapping manner.
JP 2003-285434 A

  An attachment error may occur when attaching a plurality of nozzle rows to the apparatus. Further, the fluid ejected from the nozzle may bend and land on the medium. If this happens, the image quality may deteriorate at the joint between the nozzle rows.

  Moreover, such a subject is not limited to an ink jet printer. Also in other liquid ejecting apparatuses, there is a possibility that uneven application of fluid may occur at the joint between the nozzle row and the nozzle row.

  An object of the present invention is to suppress such uneven application of fluid.

The main invention for achieving the above object is as follows: (A) a first nozzle row in which a plurality of nozzles for ejecting the first fluid are arranged in a predetermined direction; and (B) a plurality of nozzles for ejecting the first fluid. A second nozzle array arranged in the predetermined direction and arranged to partially overlap the first nozzle array in the predetermined direction; and (C) a second fluid different from the first fluid. A third nozzle row in which a plurality of nozzles to be ejected are arranged in the predetermined direction, and (D) a plurality of nozzles to inject the second fluid are arranged in the predetermined direction, and are in the predetermined direction with respect to the third nozzle row. A fourth nozzle array arranged so as to partially overlap, and (E) a first nozzle array for determining a nozzle overlapping in the predetermined direction from a plurality of nozzles of the first nozzle array and the second nozzle array. 1 data and a plurality of the third nozzle row and the fourth nozzle row A memory for storing second data for determining nozzles overlapping in the predetermined direction from among the nozzles; and (F) the first nozzle row and the second nozzle determined based on the first data. A nozzle row in which a plurality of dots are arranged in a direction intersecting the predetermined direction is formed by the nozzles that overlap each other, and the third nozzle row and the fourth nozzle row determined based on the second data overlap. A fluid ejecting apparatus including (G) a controller that forms a dot row in which a plurality of dots are arranged in a direction intersecting the predetermined direction by a nozzle.
Other features of the present invention will become apparent from the description of the present specification and the accompanying drawings.

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

(A) a first nozzle row in which a plurality of nozzles for ejecting a first fluid are arranged in a predetermined direction, and (B) a plurality of nozzles for injecting the first fluid are arranged in the predetermined direction, and the first nozzle row And (C) a plurality of nozzles for ejecting a second fluid different from the first fluid are arranged in the predetermined direction. A third nozzle row, and (D) a plurality of nozzles that eject the second fluid are arranged in the predetermined direction, and are arranged so as to partially overlap the third nozzle row in the predetermined direction. 4 nozzle rows, (E) first data for determining nozzles that overlap in the predetermined direction from a plurality of nozzles of the first nozzle row and the second nozzle row, the third nozzle row, Overlapping in the predetermined direction from among the plurality of nozzles of the fourth nozzle row (F) a memory for storing second data for determining a slip, and (F) the predetermined direction by the nozzles of the first nozzle row and the second nozzle row determined based on the first data. A direction intersecting the predetermined direction by forming a dot row in which a plurality of dots are arranged in a direction intersecting with the nozzle, and overlapping nozzles of the third nozzle row and the fourth nozzle row determined based on the second data A controller for forming a dot row in which a plurality of dots are arranged in a line and a fluid ejecting apparatus including (G) are clarified. According to such a liquid ejecting apparatus, fluid application unevenness can be suppressed.

  When the first data and the second data are different, the controller includes the number of overlapping nozzles in the first nozzle row and the second nozzle row, and the third nozzle row and the fourth nozzle row overlap. It is desirable to vary the number of nozzles. Thereby, since the setting of an overlap nozzle can be changed for every kind of fluid, application | coating nonuniformity can be suppressed also in any fluid. However, in the case where a plurality of the dot rows are formed in the predetermined direction at intervals wider than the nozzle pitch by not ejecting the fluid from the predetermined nozzles, the controller, according to the first data, A nozzle that does not eject the fluid in the second nozzle row may be set, and a nozzle that does not eject the fluid in the third nozzle row and the fourth nozzle row may be set according to the second data.

  The first fluid and the second fluid are preferably different color inks. Thereby, uneven application of ink can be suppressed for each color.

Further, (A) a first nozzle row in which a plurality of nozzles that eject the first fluid are arranged in a predetermined direction, and a plurality of nozzles that inject the first fluid are arranged in the predetermined direction, and the first nozzle row On the other hand, a second nozzle row arranged so as to partially overlap in the predetermined direction, and a third nozzle row in which a plurality of nozzles for ejecting a second fluid different from the first fluid are arranged in the predetermined direction. And a fourth nozzle row in which a plurality of nozzles for ejecting the second fluid are arranged in the predetermined direction and are arranged so as to partially overlap in the predetermined direction with respect to the third nozzle row. In the fluid ejection method, (B) a nozzle that overlaps in the predetermined direction is determined from a plurality of nozzles of the first nozzle row and the second nozzle row based on the first data, and the first data and Is based on another second data, the third nozzle row and the previous Determining overlapping nozzles in the predetermined direction from among the plurality of nozzles of the fourth nozzle row, and (C) of the first nozzle row and the second nozzle row determined based on the first data By overlapping nozzles, a dot row in which a plurality of dots are arranged in a direction intersecting the predetermined direction is formed, and the third nozzle row and the fourth nozzle row determined based on the second data are used by the overlapping nozzles. Also, a fluid ejection method having (D) forming a dot row in which a plurality of dots are arranged in a direction crossing the predetermined direction is also clarified.
According to such a fluid ejection method, fluid application unevenness can be suppressed.

=== Explanation of terms ===
First, the meanings of terms used in describing this embodiment will be described.
FIG. 1 is an explanatory diagram of terms.

“Image data” is data indicating a two-dimensional image. In an embodiment described later, there are 256 gradation image data, 4 gradation image data, and the like. When the printer controls dot formation with four gradations (large dot, medium dot, small dot, and no dot), the four gradation image data indicates the formation state of the dots constituting the print image.
A “printed image” is an image printed on a medium (for example, paper). A print image of an ink jet printer is composed of countless dots formed on paper.

A “pixel” is a minimum unit that constitutes an image. An image is formed by arranging these pixels two-dimensionally. Mainly means a pixel on the image data.
A “pixel column” is a column of pixels arranged in a predetermined direction on image data. As shown in the figure, the nth pixel column is referred to as an “nth pixel column”.

  A “raster line” is a row of dots arranged in the direction in which the head and paper move relative to each other (movement direction). In the case of a line printer as in the embodiments described later, “raster line” means a row of dots arranged in the paper transport direction. On the other hand, in the case of a serial printer that prints with a head mounted on a carriage, “raster line” means a row of dots arranged in the carriage movement direction. A print image is formed by arranging a large number of raster lines in a direction perpendicular to the moving direction. As shown in the figure, the raster line at the nth position is referred to as an “nth raster line”.

  “Pixel data” is data indicating the gradation value of a pixel. The image data is composed of a large number of pixel data. “Pixel data” is sometimes referred to as “pixel gradation value”. In the case of image data of four gradations, each pixel data is 2-bit data and indicates the dot formation state (large dot, medium dot, small dot, no dot) of a certain pixel.

  A “pixel area” is an area on paper corresponding to a pixel on image data. For example, when the resolution of the image data is 180 × 180 dpi, the “pixel area” is a square area having a side of 1/180 inch.

  A “row area” is an area on paper corresponding to a pixel row. For example, when the resolution of the image data is 180 × 180 dpi, the row area is an elongated area having a width of 1/180 inch. A row region is shown in the lower right in the figure. The “row region” is also a raster line formation target position. As shown in the figure, the row region at the nth position is referred to as an “nth row region”. The nth row region is the target position for forming the nth raster line.

  Incidentally, in the lower right of FIG. 1, the positional relationship between the pixel region and the dots is shown. In this figure, each dot is formed in a corresponding pixel region. However, the dots may not be formed in the corresponding pixel region due to the influence of the head mounting error or the flying curve of the ink. Since it is necessary to explain such a situation, in this specification, the meaning and relationship of “raster line”, “pixel region”, and the like are described in accordance with the above contents. However, the meanings of general terms such as “image data” and “pixel” may be appropriately interpreted in accordance with not only the above description but also common technical common sense.

=== First Embodiment ===
<Overall configuration>
FIG. 2 is a block diagram of the overall configuration. FIG. 3 is a perspective view for explaining the conveyance process and the dot formation process of the printer 1.

  The computer 110 is connected to the printer 1 and the scanner 120. A printer driver is installed in the computer 110. The printer driver can cause the computer 110 to generate print data and transmit the print data to the printer 1. A scanner driver is installed in the computer 110. The scanner driver can cause the scanner 120 to read a document set on the scanner 120 and acquire image data from the scanner 120.

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

  The transport unit 20 is for transporting a medium (for example, paper S) in a predetermined direction (hereinafter referred to as a transport direction). The transport unit 20 includes an upstream roller 22A and a downstream roller 22B, and a belt 24. When a conveyance motor (not shown) rotates, the upstream roller 22A and the downstream roller 22B rotate, and the belt 24 rotates. The fed paper S is conveyed by the belt 24 to a printable area (area facing the head). When the belt 24 transports the paper S, the paper S moves in the transport direction with respect to the head unit 40. The paper S that has passed through the printable area is discharged to the outside by the belt 24. The paper S being conveyed is electrostatically attracted or vacuum attracted to the belt 24.

The head unit 40 is for ejecting (also called ejecting) ink on the paper S. The head unit 40 ejects ink onto the paper S being conveyed, thereby forming dots on the paper S and printing an image on the paper S. The printer 1 of this embodiment is a line printer, and the head unit 40 can form dots for the paper width at a time.
The arrangement of the heads constituting the head unit 40 will be described later.

  The detector group 50 includes a rotary encoder (not shown) that detects the amount of rotation of the upstream roller 22A. Based on the detection result of the rotary encoder, the transport amount of the paper S can be detected.

  The controller 60 is a control unit (control unit) for controlling the printer 1. The controller 60 includes an interface unit 61, a CPU 62, a memory 63, and a unit control circuit 64. The CPU 62 is an arithmetic processing unit for controlling the entire printer. The memory 63 is for securing an area for storing a program of the CPU 62, a work area, and the like, and includes storage elements such as a RAM and an EEPROM. The CPU 62 controls each unit via the unit control circuit 64 in accordance with a program stored in the memory 63.

<Configuration of head unit 40>
FIG. 4 is an explanatory diagram of an arrangement of a plurality of heads on the lower surface of the head unit 40. As shown in the drawing, the head unit 40 includes an upstream head group 41A and a downstream head group 41B provided on the downstream side in the transport direction from the upstream head group 41A. Each of the upstream head group 41A and the downstream head group 41B has a plurality of heads 42 arranged at predetermined intervals in the paper width direction. With respect to the paper width direction, the heads 42 of each head group are provided so that the head 42 of the downstream head group 41B is positioned between the head 42 and the head 42 of the upstream head group 41A. Similarly, in the paper width direction, the heads 42 of each head group are provided so that the head 42 of the upstream head group 41A is positioned between the heads 42 of the downstream head group 41B. For this reason, the head unit 40 as a whole is configured by arranging a plurality of heads 42 in a staggered pattern along the paper width direction.
Hereinafter, for simplification of explanation, it is assumed that the head unit 40 is configured by only the upper three heads (first head 42A, second head 42B, and third head 42C) in the drawing.

  FIG. 5 is an explanatory diagram of the nozzle arrangement of each head. In each head 42, four nozzle rows are arranged in the transport direction. The four nozzle rows are a black nozzle row, a cyan nozzle row, a magenta nozzle row, and a yellow nozzle row in order from the upstream side in the transport direction. Each nozzle row includes 180 nozzles that eject ink. The 180 nozzles in each nozzle row are arranged at a constant nozzle pitch (1/180 inch in this case) along the paper width direction. In the following description, the 180 nozzles in each nozzle row are referred to as nozzle # 1, nozzle # 2,.

  The nozzles # 179 and # 180 of the first head 42A are arranged so as to be aligned with the nozzles # 1 and # 2 of the second head 42B in the paper width direction. Similarly, the nozzles # 179 and # 180 of the second head 42B are arranged so as to be aligned with the nozzles # 1 and # 2 of the third head 42C in the paper width direction. In other words, the two nozzles of the two heads 42 adjacent in the paper width direction are arranged so as to overlap each other. By overlapping the nozzles in this way, the joints of the heads can be made inconspicuous on the printed image.

<Dot formation in an ideal state>
Next, dot formation will be described. Here, description will be made assuming that each head is mounted as designed and dots are formed in an ideal state. Although the formation of dots by the black nozzle row will be described, the same applies to the formation of dots by the nozzle rows of other colors.

  FIG. 6 is an explanatory diagram of how dots are formed. In the center of the figure, the nozzles of the first head 42A are indicated by circles, and the nozzles of the second head 42B are indicated by squares. The nozzles overlapping in the paper width direction (nozzles # 179 and # 180 of the first head 42A and nozzles # 1 and # 2 of the second head 42B) are hatched. On the right side of the drawing, dots formed by the nozzles of the first head 42A are indicated by black circles, and dots formed by the nozzles of the second head 42B are indicated by black squares.

First, formation of dots in the 176th row region will be described. When receiving the print data from the computer 110, the controller 60 associates the 176th pixel column of the image data (four gradations) in the print data with the nozzle # 176 of the first head 42A. Then, the controller 60 drives a piezo element (not shown) corresponding to the nozzle # 176 according to the pixel data (four gradations) of the 176th pixel column, and ejects ink from the nozzle # 176. The ink ejected from the nozzle # 176 is landed on each pixel area of the 176th row area on the paper (because dots are formed in an ideal state here), and the 176th raster line is formed in the 176th row area. It is formed. Therefore, the 176th raster line (black raster line) is formed by one nozzle.
Note that, in the formation of dots in the 177th row region, the 178th row region, and the 181st row region to the 183rd row region as well, as in the 176th row region, the controller 60 uses each corresponding nozzle to perform rasterization. Form a line.

  Next, formation of dots in the 179th row region will be described. The controller 60 associates the 179th pixel column of the image data (four gradations) in the print data with the nozzle # 179 of the first head 42A and the nozzle # 1 of the second head 42B. That is, two nozzles are associated with one pixel row. Here, the controller 60 associates the odd-numbered pixel data of the 179th pixel column with the nozzle # 179 of the first head 42A, and associates the even-numbered pixel data with the nozzle # 2 of the second head 42B.

Then, the controller 60 drives a piezo element (not shown) corresponding to the nozzle # 176 of the first head 42A according to the odd-numbered pixel data (four gradations) of the 179th pixel column, and the ink from the nozzle # 179. To discharge. Further, the controller 60 drives a piezo element (not shown) corresponding to the nozzle # 1 of the second head 42B in accordance with the even-numbered pixel data of the 179th pixel column, and ejects ink from the nozzle # 1. The ink ejected from the nozzle # 179 of the first head 42A lands on each odd-numbered pixel area of the 179th pixel column on the paper (since dots are formed in an ideal state here). Further, the ink ejected from the nozzle # 1 of the second head 42B is landed on each even-numbered pixel region in the 179th row region on the paper (since dots are formed in an ideal state here). That is, every other dot is formed by the nozzle # 179 of the first head 42A, and every other dot is formed by the nozzle # 1 of the second head 42B so as to complement the space between these dots. Accordingly, the 179th raster line (black raster line) is formed by the two nozzles in the 179th row region.
In forming dots in the 180th row region, the controller 60 forms the 180th raster line using the corresponding two nozzles, as in the 179th row region.

  As described above, the unhatched nozzle (for example, nozzle # 176 of the first head 42A) forms a dot at each pixel in each row region. On the other hand, the hatched nozzles (for example, the nozzle # 179 of the first head 42A) form only half of the dots as compared with the non-hatched nozzles. In this way, the nozzle that is arranged side by side with the other nozzles in the transport direction and forms a smaller number of dots than a normal nozzle will be referred to as an “overlapping nozzle” in the following description. In FIG. 6, “overlapping nozzles” are hatched nozzles.

<Dot formation with head mounting error (no correction)>
FIG. 7 is an explanatory diagram of head mounting errors. Although the case where dots are formed in an ideal state has been described above, in practice, as shown in the figure, an installation error occurs in the rotation direction and the translation direction (direction parallel to the paper width direction). In some cases, dots may not be formed. Also, dots may not be formed in an ideal state when paper is conveyed while being skewed or meandered, or when ink is bent and ejected from a nozzle. Here, as shown in the figure, a case will be described in which there is an attachment error in the rotational direction at the attachment position of the second head 42B.

FIG. 8A is an explanatory diagram of how dots are formed in the black nozzle row when there is an attachment error in the rotational direction at the attachment position of the second head. The black nozzle row is a nozzle row on the upstream side in the transport direction of the second head 42B.
On the left side of the figure, the positional relationship of the black nozzle rows of the first head 42A and the second head 42B is shown. Compared with the positional relationship of the two nozzle rows in FIG. 6 (when there is no mounting error), the black nozzle row of the second head 42B is positioned on the upper side in the figure with respect to the black nozzle row of the first head 42A. is doing. As a result, the overlapping range in the paper width direction of the two nozzle rows becomes wide.
If the attachment error in the rotation direction is large, as shown in the figure, each nozzle of the second head 42B will form dots in a row region above the row region where dots are originally formed. For example, the nozzle # 1 of the second head 42B forms dots in the 178th row area, not in the 179th row area.

  On the right side of the figure, the appearance of dots formed on the paper is shown. When the nozzle having the positional relationship shown on the left side in the figure ejects ink in the same manner as in FIG. 6, more dots are formed in the 178th and 180th row areas, and this dot in the printed image A dark stripe pattern (dark streaks, ink application unevenness) is formed in a portion corresponding to the row region.

FIG. 8B is an explanatory diagram of how dots are formed in the yellow nozzle row. The yellow nozzle row is a nozzle row on the downstream side in the transport direction of the second head 42B (on the opposite side to the black nozzle row).
On the left side of the figure, the positional relationship of the yellow nozzle rows of the first head 42A and the second head 42B is shown. Compared to the case where there is no mounting error, the yellow nozzle row of the second head 42B is located on the lower side in the figure with respect to the yellow nozzle row of the first head 42A. That is, in FIG. 8B, the overlapping range in the paper width direction of the two nozzle rows is narrowed, contrary to FIG. 8A.
If the attachment error in the rotation direction is large, as shown in the drawing, each nozzle of the second head 42B forms dots in a row region below the row region where dots are originally formed. For example, the nozzle # 1 of the second head 42B forms dots in the 180th row area, not in the 179th row area.

  On the right side of the figure, the appearance of dots formed on the paper is shown. When the nozzle having the positional relationship shown on the left side in the figure ejects ink in the same manner as in FIG. 6, the number of dots formed in the 179th and 181st row areas is reduced. A light stripe pattern (light streaks, ink application unevenness) is formed in a portion corresponding to the row region.

  As described above, when there is an attachment error in the rotation direction at the attachment position of the second head 42B, a striped pattern is generated at a portion corresponding to the joint between the first head 42A and the second head 42B. Moreover, the striped pattern is different for each color.

<Processing result of this embodiment>
In order to facilitate understanding of the present embodiment, the processing result of the present embodiment will be described before the detailed description of the processing of the present embodiment.
9A and 9B are explanatory diagrams illustrating how dots are formed after the processing of this embodiment. FIG. 9A is an explanatory diagram showing how dots are formed in a black nozzle row, and FIG. 9B is an explanatory diagram showing how dots are formed in a yellow nozzle row.

  In this embodiment, if the relative positional relationship between the nozzle row of the first head 42A and the nozzle row of the second head 42B is shifted by more than half of the nozzle pitch, the setting of the overlapping nozzle is changed. For example, if the nozzle rows are shifted so that the overlapping range of the two nozzle rows in the paper width direction is wide, the overlapping nozzles are set to increase. On the other hand, if the nozzle rows are shifted so that the overlapping range in the paper width direction of the two nozzle rows is narrowed, the overlapping nozzles are set to be reduced. In addition, since the overlapping range in the paper width direction of the two nozzle rows differs for each color, in this embodiment, the setting of the overlapping nozzle is changed for each color.

As a result, when the relative positional relationship between the two black nozzle rows is as shown in FIG. 8A, the nozzle # 178 of the first head 42A and the nozzle # 3 of the second head 42B become overlapping nozzles as shown in FIG. 9A. The setting is changed so that As a result, as shown in FIG. 9A, it is not necessary to increase the number of dots in the 178th row region and the 180th row region (row region in which many dots are formed in FIG. 8A). Generation of a pattern can be suppressed.
Similarly, when the relative positional relationship between the two yellow nozzle rows is as shown in FIG. 8B, the nozzle # 179 of the first head 42A and the nozzle # 2 of the second head 42B are moved from overlapping nozzles as shown in FIG. 9B. The setting is changed to remove it. As a result, as shown in FIG. 9B, the number of dots in the 179th row area and the 181st row area (row area where few dots are formed in FIG. 8B) can be reduced, and light stripes appear in the printed image. Generation of a pattern can be suppressed.

<Process of this embodiment>
FIG. 10 is a flowchart of the process flow of this embodiment. Here, the printer driver causes the computer 110 to execute each process in the figure, or causes the printer 1 to execute control data such as print data by transmitting it to the printer 1. However, if the printer 1 has the function of a printer driver and the function of the scanner 120 (if the printer 1 is a multifunction peripheral), each process in the drawing can be executed only by the printer 1.
This process is performed after the printer 1 is manufactured and in an inspection stage before shipment.

-Print test pattern (S101)
First, the controller 60 prints a test pattern on paper (S101). The controller 60 prints a test pattern on the paper by causing the head unit 40 to eject ink from the nozzles while causing the transport unit 20 to transport the paper in the transport direction.

  FIG. 11 is an explanatory diagram of a test pattern. The test pattern includes a reference pattern P0, a first pattern P1, a second pattern P2, and a third pattern P3.

  The reference pattern P0 is composed of a large number of dots arranged at an interval of 1/180 inch along the transport direction. This reference pattern P0 is formed by the nozzle # 1 of the black nozzle row. The controller 60 causes the transport unit 20 to transport the paper in the transport direction, and prints the reference pattern P0 by ejecting ink droplets from the nozzle # 1 of the black nozzle row each time the paper is transported 1/180 inch. As will be described later, the reference pattern P0 is used for transport error detection.

  The first pattern P1 is composed of patterns of four colors (black, cyan, magenta, yellow). Here, the black pattern P1_K will be described, but the other color patterns are the same as the black pattern. The pattern P1_K is formed by at least the nozzle # 179 and the nozzle # 180 (default overlapping nozzle). Each nozzle forms five dots arranged at an interval of 1/180 inch along the transport direction. The nozzles other than the overlapping nozzles do not have to form dots. In the figure, omissible dots are indicated by white circles. As will be described later, this pattern P1_K is used to detect the position of the overlapping nozzles in the black nozzle row of the first head 42A in the paper width direction. The pattern P1_K is used to detect the relative positional relationship between the black nozzle row of the first head 42A and the black nozzle row of the second head 42B, as will be described later.

  The second pattern P2 is also composed of patterns of four colors (black, cyan, magenta, yellow). Here, the black pattern P2_K will be described, but the other color patterns are the same as the black pattern. The pattern P2_K is formed by at least nozzle # 1, nozzle # 2, nozzle # 179, and nozzle # 180 (default overlapping nozzle). Each nozzle forms five dots arranged at an interval of 1/180 inch along the transport direction. As will be described later, this pattern P2_K is used to detect the position in the paper width direction of the overlapping nozzles of the black nozzle row of the second head 42B. The pattern P2_K is used to detect the relative positional relationship between the black nozzle row of the second head 42B and the black nozzle rows of the first head 42A and the third head 42C, as will be described later.

  The third pattern P3 is also composed of patterns of four colors (black, cyan, magenta, yellow). Although the black pattern P3_K will be described here, the other color patterns are the same as the black pattern. The pattern P3_K is formed by at least nozzle # 1 and nozzle # 2 (default overlapping nozzle). (Here, for simplicity, the head unit 40 is composed of only three heads. However, when the head unit 40 has four or more heads, the third pattern P3 includes: This also includes dots formed by the nozzles # 179 and # 180 as in the second pattern P2.) Each nozzle has 5 dots arranged at an interval of 1/180 inch along the transport direction. Form. As will be described later, this pattern P3_K is used to detect the position in the paper width direction of the overlapping nozzles of the black nozzle row of the third head 42C. The pattern P3_K is used to detect the relative positional relationship between the black nozzle row of the third head 42C and the black nozzle row of the second head 42B, as will be described later.

  As shown in the figure, the controller 60 changes the pattern printing area for each head so that the first pattern P1 to the third pattern P3 do not overlap (the timing for ejecting ink is changed for each head. ).

  Further, the controller 60 intermittently ejects ink droplets from the nozzle # 1 of the black nozzle row from the start of printing of the first pattern P1 to the third pattern P3 to the end of printing, thereby forming the reference pattern P0. Thereby, the dot which comprises the reference | standard pattern P0 exists in the same position regarding a conveyance direction with respect to any pattern of the 1st pattern P1-the 3rd pattern P3.

・ Read test pattern (S102)
Next, the computer 110 causes the scanner 120 to read an image of the test pattern. The scanner 120 reads an image of a test pattern in accordance with an instruction from a scanner driver of the computer 110 and transmits image data as a reading result to the computer 110. The reading resolution of the scanner 120 is set to 4 times or more of the nozzle pitch, and here it is set to 2880 dpi (16 times the nozzle pitch).
The computer 110 performs binarization processing on the image data acquired from the scanner. However, if the image data transmitted from the scanner 120 has already been binarized, the binarization process is not necessary.

-Measurement of dot position (S103)
Next, the computer 110 analyzes the image data and measures the position of the dot formed by each nozzle. At this time, the computer 110 obtains the position of the center of gravity of the image of each dot in the image data. Since each nozzle forms five dots, the computer 110 sets the average value of the five barycentric positions as the position of the dot formed by the nozzle.

FIG. 12 is a table of dot position measurement results.
For example, the computer 110 calculates the average value of the barycentric positions of the images corresponding to the bottom five dots of the pattern P1_K of the first pattern P1 in FIG. The dot formation position of nozzle # 180 in the black nozzle row of one head 42A is set. Here, the dot formation position of the nozzle # 180 in the black nozzle row of the first head 42A is recorded as “2879”. (In other words, the dot image formed by the nozzle # 180 of the black nozzle row of the first head 42A is around the 2879th pixel row of the image data (image data having a resolution of 2880 dpi).)
For the reference pattern P0, a large number of five or more dots are formed by the same nozzle, but the computer 110 uses other patterns (pattern P1_K to pattern P1_Y of the first pattern P1, pattern P2_K to second pattern P2). P2_Y) and five dot images at the same position in the transport direction are extracted, and the average value of the barycentric positions of the five dot images is calculated.
For example, “3” is recorded here as the average value of the barycentric positions of the images corresponding to the five dots of the reference pattern P0 at the same position in the transport direction as the yellow pattern P1_Y of the first pattern P1.

-Removal of conveyance error component (S104)
When a test pattern is printed on paper, the paper may be conveyed while being skewed or meandered. In such a case, the positions of the dots constituting the test pattern are affected by transport errors such as skewing and meandering of the paper. That is, in this case, it is considered that the dot position does not accurately reflect the position of the nozzle that formed the dot. For this reason, in order to estimate the position of the nozzle from the measurement result of the dot position, it is necessary to remove the transport error component from the measurement result of the dot position.

  By the way, since the dots constituting the reference pattern P0 are formed from the same nozzle, if the dots are formed ideally, the positions of the dots should be the same. However, when the measurement result of the dot position of the reference pattern P0 in FIG. 12 is seen, the dot position has a different value. This is considered to be due to the influence of the transport error. In other words, it is considered that the dot position of the reference pattern P0 represents the component of the transport error.

  Therefore, the computer 110 calculates the difference between the measurement result of the dot position formed by each nozzle in FIG. 12 and the measurement result of the dot position of the reference pattern P0 at the same position in the transport direction as that dot. In other words, the computer 110 calculates the difference between the measurement result of the dot position formed by each nozzle in FIG. 12 and the measurement result of the dot position of the reference pattern P0 formed when the dot is formed. This difference reflects the position of the nozzle that formed each dot.

  FIG. 13 is a table of measurement results of dot positions after removal of the influence of transport errors. In other words, this table shows the position of the nozzle that formed each dot.

Calculate the relative displacement amount of the nozzle row (S105)
If a dot is ideally formed, the position of the dot formed by the nozzle # 179 of the black nozzle row of the first head 42A and the position of the dot formed by the nozzle # 1 of the black nozzle row of the second head 42B. Should be the same. However, according to the table of FIG. 13, the positions of these dots are shifted in the paper width direction by 7 pixels (7 pixels in 2880 dpi image data). In other words, the nozzle # 179 of the black nozzle row of the first head 42A and the nozzle # 1 of the black nozzle row of the second head 42B are not accurately arranged in the transport direction, and the paper width is equivalent to 7 pixels. It is thought that it is shifted in the direction.

  Therefore, the computer 110 calculates a deviation amount between default overlapping nozzles (for example, the nozzle # 179 of the black nozzle row of the first head 42A and the nozzle # 1 of the black nozzle row of the second head 42B). Since there are two sets of default overlapping nozzles between the two nozzle rows, the computer 110 calculates the average value of the two calculated deviation amounts, and uses this value as the relative deviation amount of the two nozzle rows. And

  FIG. 14 is a table showing a default deviation amount between overlapping nozzles and a relative deviation amount between two nozzle arrays. As shown in the figure, in this embodiment, the relative shift amount between the two nozzle rows is determined for each color.

・ Setting of overlapping nozzles for each color (S106)
FIG. 15 is an explanatory diagram of the relative position of the nozzle row of the second head with respect to the nozzle row of the first head. Since the nozzle pitch is 180 dpi, the nozzle pitch corresponds to 16 pixels on the 2880 dpi image data. In addition, since the width of the row area is 180 dpi, which is the same as the nozzle pit, the width of the row area corresponds to 16 pixels on the image data of 2880 dpi.

  Here, a case where the nozzle row of the second head 42B is displaced relative to the nozzle row of the first head 42A will be considered.

  When the nozzle row of the second head 42B is shifted upward in the figure with a shift amount of less than 8 pixels, the nozzle # 1 of the second head 42B can form dots in the 179th row region, and the nozzle # 2 Dots can be formed in the 180-row region. As described above, when the relative shift amount between the two nozzle rows is less than 8 pixels, the setting of the overlapping nozzle does not need to be changed as the default.

  However, when the nozzle row of the second head 42B is shifted upward in the drawing by a shift amount of 8 pixels or more, the nozzle # 1 of the second head 42B forms dots in the 178th row region, and the nozzle # 2 Forms dots in the 179th row region. In this case, it is preferable to change the setting of the overlapping nozzle. Specifically, the nozzle # 178 of the first head 42A and the nozzle # 1 of the second head 42B are paired, and the nozzle # 179 of the first head 42A and the nozzle # 2 of the second head 42B are paired. It is preferable to set overlapping nozzles by combining the nozzle # 180 of the first head 42A and the nozzle # 3 of the second head 42B.

Therefore, when the relative shift amount between the two nozzle arrays is 8 pixels (half the nozzle pitch) or more and less than 24 pixels (1.5 times the nozzle pitch), the computer 110 sets the overlapping nozzle to the default state. Change one by one. (If the amount of deviation is 24 pixels or more, it is necessary to change the setting of the overlapping nozzles by two from the default state. However, such a large amount of deviation does not occur because of the accuracy allowed when manufacturing the printer. It is like that.)
When the direction of deviation is positive (in FIG. 15, when the nozzle row of the second head 42B is shifted upward), the computer 110 changes the setting to increase the number of overlapping nozzles. When the direction of deviation is negative (in FIG. 15, the nozzle row of the second head 42B is shifted downward), the computer 110 changes the setting so as to reduce overlapping nozzles.

  FIG. 16 shows setting data for overlapping nozzles. The computer 110 creates this setting data based on the shift amount shown in FIG. As will be described later, if the setting data is zero, the setting of the overlapping nozzle is not changed as the default, and if the setting data is “1”, the setting is changed so that the number of overlapping nozzles is increased, and the setting data is “−1”. ", The setting is changed so that the number of overlapping nozzles is reduced. Thereby, when the relative deviation | shift amount of two nozzle rows exceeds half of a nozzle pitch, the setting of an overlapping nozzle is changed.

  As shown in the figure, in this embodiment, setting data for overlapping nozzles is determined for each color.

  After determining the setting data, the computer 110 stores the setting data in the memory 63 of the printer 1. That is, a printer that stores such setting data is manufactured. With the setting data stored in the memory 63 as described above, the printer 1 is packed and shipped.

<Processing during printing>
A user who has purchased a printer connects the printer 1 to the computer 110, sets a CD-ROM (storage medium) storing a printer driver (program) in the CD-ROM drive of the computer 110, and places the printer driver in the computer 110. install. Under the user, the scanner 120 may not be connected to the computer 110 as shown in FIG.

  The printer driver receives image data from the application program, converts it into print data in a format that the printer 1 can interpret, and outputs the print data to the printer. When converting image data from an application program into print data, the printer driver performs resolution conversion processing, color conversion processing, halftone processing, rasterization processing, command addition processing, and the like. Various processes performed by the printer driver will be described below.

  The resolution conversion process is a process of converting data (text data, image data, etc.) output from an application program into a resolution (print resolution) for printing on paper. For example, when the print resolution is specified as 720 × 720 dpi, vector format data received from the application program is converted into bitmap format image data with a resolution of 720 × 720 dpi. Note that each pixel data of the image data after the resolution conversion process is multi-gradation (for example, 256 gradations) RGB data represented by an RGB color space.

  The color conversion process is a process for converting RGB data into CMYK data represented by a CMYK color space. The CMYK data is data corresponding to the ink color of the printer. This color conversion process is performed based on a table (color conversion lookup table LUT) in which gradation values of RGB data and CMYK data are associated with each other. Note that the pixel data after the color conversion processing is CMYK data of 256 gradations represented by a CMYK color space.

  The halftone process is a process for converting high gradation number data into gradation number data that can be formed by a printer. For example, data representing 256 gradations is converted into 1-bit data representing 2 gradations or 2-bit data representing 4 gradations by halftone processing. In the halftone process, a dither method, a γ correction, an error diffusion method, or the like is used. The data subjected to the halftone process has a resolution equivalent to the print resolution (for example, 720 × 720 dpi). The image data after halftone processing corresponds to 1-bit or 2-bit pixel data for each pixel, and this pixel data is data indicating the dot formation status (presence / absence of dot, dot size) in each pixel. become.

  The command addition process is a process for adding command data corresponding to the printing method to the image data subjected to the halftone process. The command data includes control data for controlling the printer 1.

  The print data generated through these processes is transmitted to the printer by the printer driver.

  FIG. 17 is a flowchart of processing of the printer 1 that has received print data. Here, the controller 60 of the printer 1 executes each process in accordance with a program stored in the memory 63 or in accordance with print data control data.

・ Read setting data of overlapping nozzles (S201)
The memory 63 of the printer 1 stores overlapping nozzle setting data (see FIG. 16). The controller 60 reads the overlapping nozzle setting data from the memory 63.

-Determination of overlapping nozzles (S202)
Next, the controller 60 determines an overlapping nozzle for each color.
If the overlapping nozzle setting data is zero, the controller 60 sets the overlapping nozzle as a default. That is, when the setting data of the overlapping nozzles between the first head 42A and the second head 42B is zero for a certain color, the overlapping nozzles in the nozzle row of the first head 42A are assigned to the nozzle # 179 and the nozzle # 180, and the overlapping nozzles in the nozzle row of the second head 42B are determined as nozzle # 1 and nozzle # 2. The same applies when the setting data for the overlapping nozzles between the second head 42B and the third head 42C is zero.
For example, for cyan (C), since the setting data of the overlapping nozzles between the second head 42B and the third head 42C is zero, the controller 60 sets the overlapping nozzles in the cyan nozzle row of the second head 42B to nozzles # 179 and The nozzle # 180 is determined, and the overlapping nozzles of the cyan nozzle row of the third head 42C are determined as the nozzle # 1 and the nozzle # 2. For example, for yellow (Y), since the setting data for the overlapping nozzles between the first head 42A and the second head 42B is zero, the controller 60 sets the overlapping nozzles in the yellow nozzle row of the first head 42A to nozzle # 179. And nozzle # 180, and overlapping nozzles in the yellow nozzle row of the second head 42B are determined as nozzle # 1 and nozzle # 2.

If the overlapping nozzle setting data is “1”, the controller 60 sets the overlapping nozzle so that the number of overlapping nozzles is one more than the default setting. That is, when the setting data of the overlapping nozzles between the first head 42A and the second head 42B is “1” for a certain color, the overlapping nozzles in the nozzle row of the first head 42A are set to nozzles # 178˜ The nozzle # 180 is determined, and the overlapping nozzles of the nozzle row of the second head 42B are determined as the nozzle # 1 to the nozzle # 3. The same applies to the case where the overlapping nozzle setting data between the second head 42B and the third head 42C is “1”.
For example, for magenta (M), since the setting data of the overlapping nozzles between the second head 42B and the third head 42C is “1”, the controller 60 sets the overlapping nozzle of the magenta nozzle row of the second head 42B to the nozzle # The nozzles # 1 to # 3 are determined as the overlapping nozzles of the magenta nozzle row of the third head 42C.

If the overlapping nozzle setting data is “−1”, the controller 60 sets the overlapping nozzle so that one overlapping nozzle is reduced from the default setting. That is, when the setting data of the overlapping nozzle between the first head 42A and the second head 42B is “−1” for a certain color, the overlapping nozzle of the nozzle row of the first head 42A is set to nozzle # 180 for that color. And the overlapping nozzle in the nozzle row of the second head 42B is determined as the nozzle # 1. The same applies when the setting data of the overlapping nozzles between the second head 42B and the third head 42C is “−1”.
For example, since the setting data of the overlapping nozzle between the first head 42A and the second head 42B of magenta (M) is “−1”, the controller 60 sets the overlapping nozzle of the magenta nozzle row of the first head 42A to the nozzle nozzle. In step # 180, the overlapping nozzle in the magenta nozzle row of the second head 42B is determined as nozzle # 1.

  In the present embodiment, since the setting data is different for each color, the overlapping nozzles are different for each color.

Correlation between pixel rows and nozzles (S203)
Next, the controller 60 associates each pixel row of the image data with the nozzle for each color based on the setting of the overlapping nozzle for each color.

FIG. 18 is a correspondence table between pixel columns and nozzles when the overlapping nozzle setting is default.
When the overlapping nozzle setting is default, the controller 60 associates the nozzles # 1 to # 178 of the first head 42A with the first to 178th pixel columns. In this case, since the nozzle # 179 of the first head 42A is set as an overlapping nozzle together with the nozzle # 1 of the second head 42B, the controller 60 associates these two nozzles with the 179th pixel column. . Similarly, since the nozzle # 180 of the first head 42A is set as an overlapping nozzle together with the nozzle # 2 of the second head 42B, the controller 60 associates these two nozzles with the 180th pixel column. Then, the controller 60 associates the nozzle # 3 to the nozzle # 178 of the second head 42B with the 181st pixel row to the 356th pixel row, and the nozzle # 179 and the third head 42C of the second head 42B to the 357th pixel row. No. 1 nozzle is associated, nozzle # 180 of the second head 42B and nozzle # 2 of the third head 42C are associated with the 358th pixel row, and the nozzles of the third head 42C are associated with the pixel rows after the 359th pixel row. Associate nozzles # 3 and later.

FIG. 19 is a correspondence table between pixel columns and nozzles when the overlapping nozzle setting is that shown in FIG. Here, a correspondence between a magenta pixel row (a pixel row of magenta image data in YMCK image data) and a nozzle will be described.
When the overlapping nozzles are set as shown in FIG. 16, the controller 60 associates the nozzles # 1 to # 179 of the first head 42A with the first to 179th pixel columns. In the case of the default, up to the 178th pixel column, but in the case of FIG. 16, the number of overlapping nozzles is reduced by one, so that the pixel columns and nozzles corresponding to the 179th pixel column, which is one more than the default, are associated Is called.

Next, since the nozzle # 180 of the first head 42A is set as an overlapping nozzle together with the nozzle # 1 of the second head 42B, the controller 60 associates these two nozzles with the 180th pixel column. Compared to the default case, the number of overlapping nozzles between the first head 42A and the second head 42B is one less, so the number of pixel columns associated with the two nozzles is one less.
Then, the controller 60 associates the nozzle # 2 to the nozzle # 177 of the second head 42B with the 181st pixel row to the 356th pixel row. In the case of FIG. 16, the number of overlapping nozzles increases by one. Therefore, instead of nozzle # 178 of the second head 42B, nozzles are provided for each pixel row up to the 356th pixel row associated with the nozzle # 177 of the second head 42B. Associate.

  Thereafter, the controller 60 associates the nozzle # 178 of the second head 42B and the nozzle # 1 of the third head 42C with the 357th pixel row, and the nozzle # 179 and the third head 42C of the second head 42B with the 358th pixel row. No. # 2 is associated, nozzle # 180 of the second head 42B and nozzle # 3 of the third head 42C are associated with the 359th pixel column, and the nozzles of the third head 42C are associated with the pixel columns after the 360th pixel column. Associate nozzles # 4 and later.

In this way, the controller 60 associates each pixel row with the nozzle.
In this embodiment, since the setting of overlapping nozzles is different for each color, the nozzles associated with each pixel row are also different for each color.

-Copy of pixel rows corresponding to overlapping nozzles (S204)
Next, the controller 60 performs a copy of the pixel row corresponding to the overlapping nozzle. For example, if the 179th pixel column is associated with the overlapping nozzle, the controller 60 creates a copy of the 179th pixel column. As a result, two 179th pixel columns can be formed.
In the present embodiment, the pixel columns to be copied differ for each color.

-Mask processing on the copied pixel row (S205)
Next, the controller 60 performs a mask process on the copied pixel row (two pixel rows).
In the present embodiment, the controller 60 makes the even-numbered pixel data invalid for one of the two pixel columns (pixel data indicating that the even-numbered pixel data indicates “no dot”). Mask processing). Further, the controller 60 performs mask processing on the other pixel row so that the odd-numbered pixel data becomes invalid (so that the odd-numbered pixel data is converted into pixel data indicating “no dot”). Apply.

Ink is ejected from each nozzle according to the pixel data of each pixel column (S206)
FIG. 20 is an explanatory diagram of pixel columns used when ink is ejected from each nozzle. Here, it is assumed that the overlap nozzle setting is the default. Therefore, at this stage, as already described, the 179th pixel column and the 180th pixel column associated with the overlapping nozzle are copied (S204), and the copied pixel column is subjected to mask processing. (S205).

First, the controller 60 feeds paper to the transport unit 20, and the fed paper is transported to a printable area. Then, the controller 60 ejects ink from each nozzle according to the pixel data of each pixel row while transporting the paper to the transport unit 20.
At this time, as shown in the figure, the controller 60 controls the piezo elements of the nozzles # 1 to 178 of the first head 42A based on the pixel data of the first pixel column to the 178th pixel column, so that each nozzle Ink is ejected from the ink. Thereby, the first raster line to the 178th raster line are formed.

  In addition, the controller 60 controls the piezo element of the nozzle # 179 of the first head 42A based on one pixel column copied from the 179th pixel column, and causes ink to be ejected from the nozzle # 179. Since this pixel row is masked so that even-numbered pixel data becomes invalid, nozzle # 179 ejects ink to odd-numbered pixels. On the other hand, the controller 60 controls the piezo element of the nozzle # 1 of the second head 42B based on the other pixel column copied from the 179th pixel column, and ejects ink from the nozzle # 1. Since this pixel row is masked so that odd-numbered pixel data is invalidated, nozzle # 1 ejects ink to even-numbered pixels. As a result, a 179th raster line is formed by a set of overlapping nozzles (nozzle # 179 of the first head 42A and nozzle # 1 of the second head 42B).

  Similarly, the controller 60 controls the piezo element of the nozzle # 180 of the first head 42A based on one pixel column copied from the 180th pixel column, and causes ink to be ejected from the nozzle # 180. Since this pixel row is masked so that even-numbered pixel data becomes invalid, nozzle # 180 ejects ink to odd-numbered pixels. On the other hand, the controller 60 controls the piezo element of the nozzle # 2 of the second head 42B based on the other pixel column copied from the 180th pixel column, and causes ink to be ejected from the nozzle # 2. Since this pixel row is masked so that odd-numbered pixel data becomes invalid, nozzle # 2 ejects ink to even-numbered pixels. As a result, the 180th raster line is formed by a set of overlapping nozzles (nozzle # 180 of the first head 42A and nozzle # 2 of the second head 42B).

  Further, the controller 60 controls the piezo element of the nozzle # 3 of the second head 42B based on the pixel data of the 181st pixel column, and ejects ink from the nozzle # 3. Since the ink ejection based on the other pixel columns is the same, the description is omitted here.

  According to the present embodiment described above, the deviation amount between the black nozzle row (corresponding to the first nozzle row) of the first head 42A and the black nozzle row (corresponding to the second nozzle row) of the second head 42B in S105. Is required. When this deviation amount is smaller than half of the nozzle pitch, the number of overlapping nozzle sets is set to two sets as a default setting. However, when the deviation amount is larger than half of the nozzle pitch, the default setting is changed. For example, if the two nozzle arrays are shifted in the overlapping direction, the setting is changed so that the number of overlapping nozzle sets is increased from the default setting (see FIG. 9A). Also, if the two nozzle rows are displaced in a direction that does not overlap, the setting is changed so that the number of overlapping nozzle sets is reduced from the default setting (see FIG. 9B). Thereby, the shift | offset | difference of a dot can be settled in half or less of a nozzle pitch, and it can suppress that a striped pattern arises in a printed image.

  In addition, according to the present embodiment, a test pattern (see FIG. 11) is printed in S101, and the positions of the dots of the first pattern P1 and the second pattern P2 of the test pattern are measured in S102 and S103. Based on this, in S105, the amount of deviation between the black nozzle row (corresponding to the first nozzle row) of the first head 42A and the black nozzle row (corresponding to the second nozzle row) of the second head 42B is obtained. Thereby, the amount of deviation can be obtained by a simple method. Further, it is possible to obtain the amount of deviation in consideration of the flying curve of the ink. If the amount of deviation is obtained by directly measuring the mounting position of the nozzles, the measurement is difficult, and it becomes impossible to set overlapping nozzles in consideration of the influence of the ink flight curve.

  Further, according to the present embodiment, by discharging ink from the nozzle # 1 (corresponding to a specific nozzle) of the black nozzle row from the start of printing of the first pattern P1 and the second pattern P2 to the end of printing, A reference pattern P0 is formed. The positions of the dots constituting this reference pattern are considered to reflect the influence of the transport error. Therefore, in S104, the measurement position of the dot of the first pattern is corrected by the measurement position of the dot of the reference pattern formed when the dot is formed. In S104, similarly, the measurement position of the dot of the first pattern is corrected by the measurement position of the dot of the reference pattern formed when the dot is formed. Thereby, the relative deviation amount can be obtained without being influenced by the conveyance error.

  Further, in the present embodiment, since overlapping nozzles are set independently for each color, it is possible to suppress the occurrence of a striped pattern in the printed image as shown in FIGS. 9A and 9B.

=== Modification Example of Mask Processing ===
In the above-described embodiment, no matter which pixel column is copied in S204, mask processing is performed so that even-numbered pixels are invalidated for one of the two pixel columns. On the other hand, mask processing is performed so that odd-numbered pixels are invalidated. However, it is not limited to this.

  FIG. 21A is an explanatory diagram of a modified example of the mask process. Here, for convenience of explanation, it is assumed that there are three sets of overlapping nozzles.

  For the pixel rows corresponding to the overlapping nozzles (nozzles # 178 to 180) of the first head 42A, the controller 60 performs mask processing so that the pixel rows corresponding to the nozzles at the end increase the invalid pixel data. . For example, the controller performs mask processing so that half the pixel data is invalidated for the pixel row corresponding to the nozzle # 179, but the pixel row corresponding to the nozzle # 180 outside the nozzle # 179. Is masked so that the pixel data becomes invalid at a rate of 3/4. Further, mask processing is performed on the pixel column corresponding to the nozzle # 178 located inside the nozzle # 179 so that the pixel column becomes invalid at a ratio of 1/4.

  Similarly, for the pixel columns corresponding to the overlapping nozzles (nozzles # 1 to # 3) of the second head 42B, the controller 60 increases the amount of pixel data to be invalidated in the pixel column corresponding to the end nozzle. Then, mask processing is performed. For example, the controller performs mask processing so that half of the pixel data is invalidated for the pixel row corresponding to nozzle # 2, but the pixel row corresponding to nozzle # 1 outside nozzle # 2. Is masked so that the pixel data becomes invalid at a rate of 3/4. Further, mask processing is performed on the pixel row corresponding to the nozzle # 3 located inside the nozzle # 2 so that the pixel row becomes invalid at a ratio of 1/4.

  The two masks for the two pixel columns copied from the common pixel column have an inverted relationship between the locations of the pixel data to be invalidated. For example, one mask for the two pixel columns copied from the 178th pixel column invalidates the pixel data of the fourth multiple (for example, fourth and eighth) from the left and leaves the other pixel data as they are. However, the other mask leaves the pixel data that is a multiple of 4 from the left as it is, and invalidates the other pixel data. One mask for the two pixel columns copied from the 179th pixel column invalidates the even-numbered pixel data and leaves the odd-numbered pixel data as it is, but the other mask has the even-numbered pixel data. The data is left as it is, and the odd-numbered pixel data is invalidated. In the two masks for the two pixel columns copied from the 180th pixel column, the locations of the pixel data to be invalidated are in an inverted relationship as shown in FIG. 21A.

FIG. 21B is an explanatory diagram of how dots are formed when the mask processing according to the modification is performed.
When attention is paid to the 178th raster line formed in the 178th row region, the number of dots formed by the nozzles of the first head 42A is increased and the number of dots formed by the nozzles of the second head 42B is larger than in the above-described embodiment. decreasing. On the contrary, when attention is paid to the 180th raster line formed in the 180th row region, the number of dots formed by the nozzles of the first head 42A is smaller than that of the previous embodiment, and the dots are formed by the nozzles of the second head 42B. The number of dots has increased. As a result, from the top to the bottom of the row area in the figure, the contribution ratio of the first head changes so as to gradually decrease, and the contribution ratio of the second head changes so as to gradually increase.

  By the way, when there is a difference in ink ejection characteristics between the first head and the second head due to a manufacturing error, there is a difference between the print image formed by the first head 42A and the print image formed by the second head 42B. May cause a difference in image quality. However, according to this modification, the image quality gradually changes from the 178th column region to the 180th column region, so that the boundary of the print image is less noticeable and the image quality of the entire print image is improved. If the mask processing of this modification is performed for each color, the image quality of the printed image of each color can be improved.

=== Second Embodiment ===
In the above-described embodiment, the nozzle pitch and the printing resolution are the same, but the present invention is not limited to this. In the second embodiment, the nozzle pitch and the printing resolution are different.

FIG. 22 is an explanatory diagram of how dots are formed in the ideal state according to the second embodiment.
In the second embodiment, each nozzle row includes 360 nozzles (180 in the first embodiment), and the nozzle pitch is 1/360 inch (1/180 inch in the first embodiment).
Similar to the first embodiment, the pixel rows of the image data and the raster lines of the print image have a one-to-one correspondence. However, the relationship between the pixel row and the nozzle and the relationship between the nozzle and the raster line are different from the first embodiment in that they do not correspond one-on-one.
In an ideal state, an even-numbered nozzle is associated with each pixel row. Then, by ejecting ink from even-numbered nozzles, raster lines are formed at an interval twice the nozzle pitch. For example, the nozzle # 352 of the first head 42A is associated with the 176th pixel column, and ink is ejected from the nozzle # 352 to form the 176th raster line.

  In an ideal state, the nozzle # 358 of the first head 42A and the nozzle # 2 of the second head 42B form a set of overlapping nozzles. Then, the controller 60 drives a piezo element (not shown) corresponding to the nozzle # 358 of the first head 42A in accordance with the odd-numbered pixel data (four gradations) of the 179th pixel row, thereby causing the ink from the nozzle # 358 to ink. Then, a piezo element (not shown) corresponding to the nozzle # 2 of the second head 42B is driven according to the even-numbered pixel data in the 179th pixel column, and ink is ejected from the nozzle # 2. As a result, a 179th raster line is formed by two nozzles in the 179th row region. The nozzle # 360 of the first head 42A and the nozzle # 4 of the second head 42B also form a set of overlapping nozzles, and the 180th raster line is formed in the 180th row region by these two nozzles.

  FIG. 23 is an explanatory diagram when there is an attachment error in the second head 42B. In the first embodiment, when the relative shift amount between the two nozzle rows is 1/360 inch (8 pixels on 2880 dpi image data, half the nozzle pitch) or more, the setting of the overlapping nozzle is changed. is doing. On the other hand, in the second embodiment, since the nozzles for ejecting ink can be changed, the relative displacement between the two nozzle rows is 1/720 inch (4 pixels on 2880 dpi image data, the nozzle pitch is In the case of half or more, the setting of the overlapping nozzle is changed.

  In the second embodiment described above, by not ejecting ink from a predetermined nozzle, the interval between nozzles that eject ink is set to 1/180 inch as in the first embodiment. For this reason, even in the case of such a nozzle configuration, it is possible to perform the same processing as in the first embodiment, and it is also possible to obtain the same effect.

In the case of the nozzle configuration as in the second embodiment, the nozzle pitch is narrower than in the first embodiment. According to the first embodiment and the second embodiment, since the dot shift can be suppressed to half or less of the nozzle pitch, the dot shift of the second embodiment with a narrow nozzle pitch is smaller than that of the first embodiment. It is possible to suppress.
In the case of the second embodiment, when the deviation amount is half or more of the nozzle pitch, ink is ejected from nozzles that do not eject ink in the default setting. As a result, it is possible to suppress the dot shift more than in the first embodiment.

=== Other Embodiments ===
Although a printer or the like as one embodiment has been described, the above embodiment is intended to facilitate understanding of the present invention, and is not intended to limit the present invention. The present invention can be changed and improved without departing from the gist thereof, and it is needless to say that the present invention includes equivalents thereof. In particular, the embodiments described below are also included in the present invention.

<About the printer>
In the above-described embodiment, an ink jet printer is described as an example of the liquid ejecting apparatus. However, the liquid ejecting apparatus is not limited to the ink jet printer, and liquids other than ink (including liquids in which functional material particles are dispersed and liquids such as gels) and liquids other than inks are also included. The present invention is also applicable to a fluid ejecting apparatus that ejects a fluid (a solid that can be ejected as a fluid, such as powder). For example, an injection device for injecting a liquid colorant or an electrode material used for manufacturing a liquid crystal display, an EL display and a surface emitting display, or an injection device for injecting a liquid bioorganic material used for biochip manufacturing The embodiment may be applied.

<About ink>
Since the above-described embodiment is an embodiment of a printer, ink is ejected from the nozzles, but this ink may be water-based or oil-based. The fluid ejected from the nozzle is not limited to ink. For example, liquids (including water) including metal materials, organic materials (especially polymer materials), magnetic materials, conductive materials, wiring materials, film-forming materials, electronic inks, processing liquids, gene solutions, etc. are ejected from nozzles. May be.

<About media>
In the above-described embodiment, the medium from which the fluid is ejected from the nozzle is paper. However, the medium is not limited to paper. For example, a cloth, an OHP sheet, a liquid crystal substrate, a semiconductor wafer, or the like may be used.

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

<About line printers>
In the above-described embodiment, the head unit 40 is fixed, and the nozzle row and the paper (corresponding to the medium) are relatively moved by transporting the paper by the transport unit 20, but this is not limited thereto. It is not a thing.
For example, a carriage that moves in the main scanning direction may be provided, a head unit may be provided on the carriage, and the nozzle row and the paper may be moved relative to each other by moving the carriage. In this case, the print image is formed on the paper by alternately repeating the operation of moving the carriage and ejecting ink from the nozzles and the operation of transporting the paper by the transport unit.

<Regarding the reference pattern P0>
According to the test pattern described above, the reference pattern P0 is formed (see FIG. 11). However, the reference pattern P0 may be omitted if the influence of the transport error is not considered.

<About setting data>
According to the above-described embodiment, the setting data for overlapping nozzles is prepared for each color. However, the present invention is not limited to this.
For example, if only the installation error in the translation direction and the rotation direction in FIG. 7 is considered without considering the influence of the flying curve of ink, only black and yellow setting data are prepared, and cyan and magenta setting data are prepared. It can be omitted. In this case, it is preferable to use an average value of black and yellow setting data for setting the cyan and magenta overlapping nozzles.

<About the printer driver>
In the above-described embodiment, the printer-side controller performs each process of S201 to S206 in FIG. However, these processes are not necessarily performed on the printer side.

  For example, the printer driver may read the overlapping nozzle setting data stored in the printer memory, and perform the processing of S202 to S206 on the image data after the halftone processing.

It is explanatory drawing of a term. It is a block diagram of the whole structure. FIG. 6 is a perspective view for explaining a conveyance process and a dot formation process of a printer. It is explanatory drawing of the arrangement | sequence of the some head in the lower surface of a head unit. It is explanatory drawing of arrangement | positioning of the nozzle of each head. It is explanatory drawing of the mode of formation of a dot. It is explanatory drawing of the attachment error of a head. FIG. 8A is an explanatory diagram of how dots are formed in the black nozzle row when there is an attachment error in the rotational direction at the attachment position of the second head. FIG. 8B is an explanatory diagram of how dots are formed in the yellow nozzle row. 9A and 9B are explanatory diagrams illustrating how dots are formed after the processing of this embodiment. FIG. 9A is an explanatory diagram showing how dots are formed in a black nozzle row, and FIG. 9B is an explanatory diagram showing how dots are formed in a yellow nozzle row. It is a flowchart of the flow of the process of this embodiment. It is explanatory drawing of a test pattern. It is a table | surface of the measurement result of the position of a dot. It is a table | surface of the measurement result of the position of the dot after the influence removal of a conveyance error is removed. It is a table | surface which shows the deviation | shift amount of default overlapping nozzles, and the relative deviation | shift amount of two nozzle rows. It is explanatory drawing of the relative position of the nozzle row of a 2nd head with respect to the nozzle row of a 1st head. This is setting data for overlapping nozzles. It is a flowchart of the process of the printer 1 which received print data. 10 is a correspondence table between pixel rows and nozzles when the setting of overlapping nozzles is default. FIG. 17 is a correspondence table between pixel rows and nozzles when the setting of overlapping nozzles is shown in FIG. 16. It is explanatory drawing of the pixel row | line used when discharging ink from each nozzle. FIG. 21A is an explanatory diagram of a modified example of the mask process. FIG. 22B is an explanatory diagram of how dots are formed when the mask processing according to the modification is performed. It is explanatory drawing of the mode of the formation of the dot in the ideal state of 2nd Embodiment. It is explanatory drawing when there is an attachment error in the 2nd head 42B.

Explanation of symbols

1 printer,
20 conveying unit, 22A upstream roller, 22B downstream roller, 24 belt,
40 head units, 41A upstream head group, 41B downstream head group,
42 heads, 42A first head, 42B second head, 42C third head,
50 detector groups,
60 controller, 61 interface unit, 62 CPU, 63 memory,
64 unit control circuit,
110 computers, 120 scanners

Claims (5)

(A) a first nozzle row in which a plurality of nozzles that eject the first fluid are arranged in a predetermined direction;
(B) a plurality of nozzles that eject the first fluid are arranged in the predetermined direction, and a second nozzle row that is arranged so as to partially overlap the first nozzle row in the predetermined direction;
(C) a third nozzle row in which a plurality of nozzles that eject a second fluid different from the first fluid are arranged in the predetermined direction;
(D) a fourth nozzle row in which a plurality of nozzles that eject the second fluid are arranged in the predetermined direction, and are arranged so as to partially overlap the third nozzle row in the predetermined direction;
(E) first data for determining nozzles that overlap in the predetermined direction from among the plurality of nozzles of the first nozzle row and the second nozzle row, and the third data of the third nozzle row and the fourth nozzle row A memory for storing second data for determining nozzles overlapping in the predetermined direction from among a plurality of nozzles;
(F) forming a dot row in which a plurality of dots are arranged in a direction intersecting the predetermined direction by the overlapping nozzles of the first nozzle row and the second nozzle row determined based on the first data;
A controller that forms a dot row in which a plurality of dots are arranged in a direction intersecting the predetermined direction by the overlapping nozzles of the third nozzle row and the fourth nozzle row determined based on the second data;
A fluid ejection device comprising (G). The fluid ejection device according to claim 1,
When the first data and the second data are different, the controller overlaps the number of nozzles that overlap the first nozzle row and the second nozzle row, and overlaps the third nozzle row and the fourth nozzle row. A fluid ejecting apparatus, wherein the number of nozzles is different. The fluid ejection device according to claim 1,
When the plurality of dot rows are formed in the predetermined direction at intervals wider than the nozzle pitch by not ejecting the fluid from the predetermined nozzles, the controller may select the first nozzle rows and the first nozzles according to the first data. A nozzle that does not eject the fluid in two nozzle rows is set, and a nozzle that does not eject the fluid is set in the third nozzle row and the fourth nozzle row according to the second data. . The fluid ejecting apparatus according to claim 1,
The fluid ejecting apparatus, wherein the first fluid and the second fluid are inks of different colors. (A) a first nozzle row in which a plurality of nozzles that eject the first fluid are arranged in a predetermined direction;
A plurality of nozzles for injecting the first fluid are arranged in the predetermined direction, and a second nozzle row arranged so as to partially overlap the first nozzle row in the predetermined direction;
A third nozzle row in which a plurality of nozzles for ejecting a second fluid different from the first fluid are arranged in the predetermined direction;
Fluid ejection using a fourth nozzle array in which a plurality of nozzles that eject the second fluid are arranged in the predetermined direction and are arranged so as to partially overlap the third nozzle array in the predetermined direction A method,
(B) Based on the first data, determine a nozzle that overlaps in the predetermined direction from a plurality of nozzles of the first nozzle row and the second nozzle row,
Determining a nozzle overlapping in the predetermined direction from a plurality of nozzles of the third nozzle row and the fourth nozzle row based on second data different from the first data; and
(C) forming a dot row in which a plurality of dots are arranged in a direction crossing the predetermined direction by the overlapping nozzles of the first nozzle row and the second nozzle row determined based on the first data;
(D) forming a dot row in which a plurality of dots are arranged in a direction intersecting the predetermined direction by the overlapping nozzles of the third nozzle row and the fourth nozzle row determined based on the second data (D) A fluid ejection method.

Images