JP2011245714A - Fluid ejecting apparatus, and fluid ejecting method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress image quality deterioration of an image.SOLUTION: The fluid ejecting apparatus has a controller configured to repeatedly carry out image forming operation for ejecting fluid from nozzles while relatively moving a medium and a nozzle train in a direction crossing a predetermined direction, and operation for moving the relative position of the medium to the nozzle train in the predetermined direction, and to form an image on the medium by performing intermediate processing between regular processing for forming the image at a center part in the predetermined direction of the medium, and end processing for forming the image at the end in the predetermined direction of the medium, the end processing in which a relative moving amount in the predetermined direction of the medium to the nozzle train is smaller than a relative moving amount in the regular processing. In the intermediate processing, a relative moving amount is larger than the relative moving amount in the end processing and a half of the relative moving amount in the regular processing.

Description

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

As one of the fluid ejecting apparatuses, a head having a nozzle row in which nozzles for ejecting ink (fluid) are arranged in a predetermined direction ejects ink from the nozzles to the medium while moving in a moving direction intersecting the predetermined direction. 2. Related Art Inkjet printers (hereinafter referred to as printers) that repeat an image forming operation for forming an image and a transport operation for transporting the relative position of a head and a medium in a predetermined direction are known.

Some printers start and end printing at the beginning and end of printing to reduce the amount of protrusion of the head relative to the medium and the amount of margin of the medium. However, there is a printer that reduces the amount of movement of the relative position of the head and the medium (see, for example, Patent Document 1).

Japanese Patent Laid-Open No. 7-242025

A defective nozzle group having different ejection characteristics from other nozzles may occur in a part of the nozzle row. Then, since the relative movement amount of the head and the medium is small at the start and end of printing,
Defective nozzles are continuously assigned to some raster lines (dot rows along the moving direction). That is, the number of defective nozzles assigned to one raster line increases. As a result, raster lines to which many defective nozzles are assigned appear as streaks on the image, and the image quality of the image deteriorates.
Therefore, an object of the present invention is to suppress image quality deterioration of an image.

The main invention for solving the above problems is: (A) a nozzle row in which nozzles for ejecting fluid to the medium are arranged in a predetermined direction; and (B) a direction in which the medium and the nozzle row intersect the predetermined direction. A controller that repeatedly executes an image forming operation of ejecting fluid from the nozzle while relatively moving, and an operation of moving the relative position of the medium with respect to the nozzle row in one direction of the predetermined direction, A normal processing for forming an image at a central portion of the medium in the predetermined direction, and an end processing for forming an image at an end of the medium in the predetermined direction, the medium being directed to the nozzle row in the predetermined direction. The relative movement amount is longer than the relative movement amount of the end portion processing and the end portion processing is shorter than the relative movement amount of the normal processing, and the normal processing amount. By carrying out the intermediate treatment is half of the serial relative movement amount, and a control unit for forming an image on the medium is a fluid jet apparatus characterized by having (C).
Other features of the present invention will become apparent from the description of this specification and the accompanying drawings.

1 is an overall configuration block diagram of a printer. FIG. 2A is a perspective view of the printer, and FIG. 2B is a diagram showing a nozzle arrangement in the head. 3A and 3B are diagrams illustrating a printing method of a comparative example. 4A and 4B are diagrams for explaining the printing method of the present embodiment. It is a graph which shows the difference in the usage rate of the defective nozzle in the printing method of a comparative example, and the printing method of this embodiment. It is a figure which shows the usage-ratio of a defective nozzle in case the number of defective nozzles is four. It is a figure which shows the usage rate of a defective nozzle in case the number of defective nozzles is eight. It is a figure which shows the usage rate of a defective nozzle in case the number of defective nozzles is 16. It is a figure which shows the usage-ratio of a defective nozzle in case the number of passes of an intermediate process is 3. It is a figure which shows the usage-ratio of a defective nozzle when the number of passes of an intermediate process is 2. It is a figure which shows the usage-ratio of a defective nozzle when the number of passes of an intermediate process is 1. It is a figure which shows the usage-ratio of the defective nozzle with respect to the lower end side of a medium. FIG. 9A is a diagram illustrating a printing method when the intermediate processing medium conveyance amount is discarded, and FIG. 9B is a diagram illustrating a printing method when the intermediate processing medium conveyance amount is rounded up. It is a figure which shows the usage rate of a defective nozzle when eight defective nozzles generate | occur | produce. It is a figure which shows the usage rate of a defective nozzle when four defective nozzles generate | occur | produce. FIG. 11A and FIG. 11B are diagrams for explaining the usage ratio of defective nozzles when defective nozzles are generated at the ends. FIG. 12A and FIG. 12B are diagrams for explaining the usage ratio of defective nozzles when defective nozzles are generated between the end portion and the central portion.

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

That is, (A) a nozzle row in which nozzles for ejecting fluid to the medium are arranged in a predetermined direction, and (B)
An image forming operation for ejecting fluid from the nozzle while relatively moving the medium and the nozzle row in a direction intersecting the predetermined direction, and moving the relative position of the medium with respect to the nozzle row in one direction of the predetermined direction A control unit that repeatedly executes an operation of: a normal process for forming an image at a central portion of the medium in the predetermined direction; and an end process for forming an image at an end portion of the medium in the predetermined direction. The relative movement amount of the medium with respect to the nozzle row in the predetermined direction is shorter than the relative movement amount of the normal process.
A control unit that forms an image on the medium by performing intermediate processing in which the relative movement amount is longer than the relative movement amount of the edge processing and is half the relative movement amount of the normal processing. And (C).
According to such a fluid ejecting apparatus, it is possible to reduce the ratio of defective nozzles used when forming dot rows along intersecting directions, and to suppress image quality deterioration.

In this fluid ejecting apparatus, the nozzle row is the nozzle row belonging to one head.
According to such a fluid ejecting apparatus, it is possible to reduce the ratio of defective nozzles used when forming dot rows along intersecting directions, and to suppress image quality deterioration.

In this fluid ejecting apparatus, when the first number that is the number of dot rows along the intersecting direction corresponding to the relative movement amount of the normal process is an odd number, the relative movement amount of the intermediate process The number of dot rows corresponding to is the integer part of the value obtained by dividing the first number by 2 or the number obtained by adding 1 to the integer part.
According to such a fluid ejecting apparatus, the relative movement amount of the intermediate process can be determined.

Further, an image forming operation for ejecting fluid from the nozzle while relatively moving a nozzle row and a medium in which nozzles for ejecting fluid are arranged in a predetermined direction in a direction intersecting the predetermined direction, and the relative of the medium to the nozzle row An operation of moving the position in one direction of the predetermined direction, and a fluid ejection method in which a normal process for forming an image at a central portion of the medium in the predetermined direction, and in the predetermined direction of the medium An edge process for forming an image at an edge, wherein the relative movement amount of the medium relative to the nozzle row in the predetermined direction is shorter than the relative movement amount of the normal process; A fluid ejection method characterized in that an intermediate process is performed in which the relative movement amount is longer than the relative movement amount of the edge processing and is half the relative movement amount of the normal process. It is.
According to such a fluid ejecting method, it is possible to reduce the ratio of defective nozzles used when forming dot rows along intersecting directions, and to suppress image quality deterioration.

=== About the printing system ===
Hereinafter, an embodiment will be described with an example of a printing system in which a fluid ejecting apparatus is an inkjet printer (hereinafter referred to as a printer) and a printer and a computer are connected.

FIG. 1 is a block diagram of the overall configuration of the printer 1. FIG. 2A is a perspective view of the printer 1, and FIG. 2B is a diagram showing a nozzle arrangement in the head 41. Computer 60
Is connected to the printer 1 in a communicable manner, and outputs print data for causing the printer 1 to print an image to the printer 1. The computer 60 is installed with a program (printer driver) for converting image data output from the application program into print data. The printer driver is a CD-ROM
Or can be downloaded to a computer via the Internet.

The controller 10 is a control unit for controlling the printer 1. The interface unit 11 is for transmitting and receiving data between the computer 60 and the printer 1. The CPU 12 is an arithmetic processing unit for controlling the entire printer 1. The memory 13 is for securing an area for storing a program of the CPU 12, a work area, and the like. The CPU 12 controls each unit by the unit control circuit 14. The detector group 50 monitors the situation in the printer 1, and the controller 10 controls each unit based on the detection result.

The transport unit 20 feeds the medium S (printing paper or the like) to a printable position, and transports the medium S by a predetermined transport amount in the transport direction (predetermined direction) during printing.
The carriage unit 30 is for moving the head 41 in a movement direction that intersects the conveyance direction, and includes a carriage 31.

The head unit 40 is for ejecting ink onto the medium S and has a head 41. The head 41 is moved in the movement direction by the carriage 31. As shown in FIG. 2B, a plurality of nozzles that are ink ejecting portions are provided on the lower surface of the head 41, and an ink chamber (not shown) containing ink is provided in each nozzle. FIG. 2B is a diagram in which the nozzle is virtually seen from the upper surface of the head 41. The head 41 is provided with four nozzle rows (yellow nozzle row Y, magenta nozzle row M, cyan nozzle row C, and black nozzle row K) that respectively eject four colors of ink. In each nozzle row, 360 nozzles are arranged at a predetermined interval (360 dpi) in the medium transport direction. Small numbers are assigned in order from the nozzles on the downstream side in the transport direction (# 1 to # 360).

In such a printer 1, an image forming operation (pass) in which ink droplets are intermittently ejected from the head 41 moving in the moving direction to form dots on the medium, and the medium is moved to the head 41.
The transport operation for transporting in the transport direction is repeated. By doing so, dots can be formed by a subsequent image forming operation at a position on the medium different from the position of the dot formed by the previous image forming operation, and a two-dimensional image is printed on the medium. can do.

=== Printing Method of Comparative Example ===
FIG. 3A is a diagram illustrating a printing method of a comparative example for the upper end portion of the medium, and FIG. 3B is a diagram illustrating a printing method of the comparative example for the lower end portion of the medium. An end portion on the downstream side in the transport direction in the medium is referred to as an “upper end portion”, and an end portion on the upstream side in the transport direction in the medium is referred to as a “lower end portion”. The printing method of the comparative example includes an upper end process for printing the upper end part of the medium, a lower end process for printing the lower end part of the medium, and a normal process for printing a part other than the end part (the center part of the medium). As shown in FIG. 3A, passes 1 to 4 are set as upper end processing, passes 5 and after are set as normal processing, and FIG.
As shown in FIG. 4, the process up to pass 11 is the normal process, and the process from pass 12 to pass 15 is the lower end process. In the figure, one square is represented as one nozzle, and the number of nozzles belonging to the nozzle row is reduced to 64. In the actual printer 1, the medium is transported downstream in the transport direction with respect to the head 41 (nozzle array). In the drawing, the nozzle array is shifted upstream in the transport direction for each pass. In addition, the interval between the nozzles arranged in the transport direction in the nozzle row (the length in the transport direction of the squares) is “D”.

Here, a printing method (so-called overlap printing) in which one raster line (dot row along the moving direction) is printed with a plurality of nozzles is taken as an example. Assuming that a unit area where one dot is formed on the medium is a “pixel area”, raster lines are formed in a plurality of pixel areas arranged in the moving direction. It is assumed that the pixel areas arranged in the moving direction are classified into four, and any one of the four horizontal positions (1 to 4) is associated with each pixel area. In normal processing, dots are formed by two nozzles for the pixel region at each horizontal position. That is, in the normal process, one raster line is printed with eight nozzles. A nozzle that forms dots together with other nozzles in a pixel region at the same horizontal position in this way is referred to as an “overlap nozzle (hereinafter referred to as an OL nozzle)”. In the figure, OL nozzles are indicated by hatched cells. Also, numbers are assigned in order from the raster line on the downstream side in the transport direction, and for example, the raster line located on the most downstream side in the transport direction is referred to as “first raster (L1)”. In the position corresponding to the 52nd raster (L52) shown in FIG. 3A, 8 OL nozzles are arranged in the moving direction.
It shows that it is formed by the L nozzle.

In FIG. 3, the interval between the raster lines arranged in the transport direction is “D”. Therefore, in the normal processing, the medium transport amount per time is “8D”, and the number of raster lines corresponding to the medium transport amount is “8”. That is, in the normal process, the medium is transferred to the head 41 by one medium transport operation.
On the other hand, it is conveyed downstream by 8 raster lines in the conveying direction. In summary,
In the normal processing, an image forming operation in which ink droplets are ejected from 64 nozzles belonging to the nozzle row while moving the nozzle row in the moving direction, and medium conveyance for conveying the medium by a conveyance amount “8D” downstream in the conveyance direction. The operation is repeated.

Here, if the normal process is performed from the start of printing, the print start position with respect to the head 41 becomes upstream in the transport direction. Conversely, if normal processing is performed until the end of printing, the print end position with respect to the head 41 becomes downstream in the transport direction. Then
The margin of the medium becomes large, and the amount of protrusion of the head 41 with respect to the medium becomes large. Therefore, in the printing method of the comparative example, at the start of printing, that is, at the time of printing at the upper end portion of the medium, the upper end process in which the medium conveyance amount is “D” shorter than the medium conveyance amount 8D of the normal process is performed, That is, at the time of printing the lower end portion of the medium, the lower end process in which the medium transport amount is “D” shorter than the medium transport amount 8D of the normal process is performed. That is, the medium conveyance amount in the upper end process and the lower end process corresponds to the length of one raster line.

In addition, the number of nozzles assigned to the raster line is small at the upper end portion and the lower end portion of the medium (the number of cells arranged in the moving direction is small). Therefore, as in normal processing, one raster line may not be formed with eight nozzles. Therefore, in the upper end process and the lower end process, a part of the nozzles is caused to play a role of two nozzles during normal processing. That is, dots are formed on one nozzle for all pixel regions at a certain horizontal position.
In this manner, a nozzle that forms dots with only its own nozzle in a pixel region at the same horizontal position is referred to as a “normal nozzle”. In the figure, normal nozzles are indicated by white squares.

On the other hand, since a normal process nozzle is also assigned to a raster line to which a nozzle (a nozzle with a large number) on the upstream side in the transport direction is assigned in the upper end process nozzle row, the number of nozzles assigned to the raster line is eight or more. It becomes. Similarly, since the normal processing nozzles are also assigned to the raster lines to which the nozzles in the transport direction downstream side (nozzles with a smaller number) are assigned in the lower end processing nozzle row, the number of nozzles assigned to the raster line is eight. That's it. In the printing method of the comparative example, when the number of nozzles assigned to one raster line is 8 or more, the normal processing nozzle is used in preference to the upper end processing nozzle, and the lower end processing nozzle is usually used. The processing nozzle is preferentially used for printing. Also, in the same upper end process, the nozzles in the subsequent pass are used for printing preferentially in the previous pass process, and in the same lower end process, the nozzles in the previous pass than the nozzles in the subsequent pass are used. Priority should be given to printing.

Therefore, nozzles that are not used for printing (hereinafter referred to as non-use nozzles) are generated in the nozzle row for the upper end process and the nozzle row for the lower end process. In the figure, non-use nozzles are indicated by crosses. As shown in the drawing, the nozzle on the upstream side in the transport direction in the nozzle row for the upper end process is an unused nozzle, and the nozzle on the downstream side in the transport direction in the nozzle row for the lower end process is an unused nozzle. Note that the nozzles on the downstream side of the print start position and the nozzles on the upstream side of the print end position are also non-use nozzles.

By the way, a defective nozzle may occur locally in one head 41 (nozzle row) due to a change with time. A defective nozzle is a nozzle whose ink ejection amount has fluctuated from the designed ejection amount, or a nozzle whose ink droplet landing position has deviated from the designed landing position. Here, for example, it is assumed that a defective nozzle group in which the ink ejection amount is smaller than the designed ejection amount is generated at the center of the nozzle row. As shown in the drawing, a region (eight nozzles # 29 to # 36) surrounded by a thick frame at the center of the nozzle row is defined as a defective nozzle group.

In normal processing (after pass 5), the medium transport amount is relatively large. Therefore, the raster line group to which the defective nozzle group is assigned in a certain pass does not overlap with the raster line group to which the defective nozzle group is assigned in the previous and subsequent passes. Therefore, only one defective nozzle is assigned to the raster line to which the defective nozzle is assigned in the normal processing pass. For example,
No. 45 raster (L) to which the defective nozzle # 29 is assigned in the normal process pass 6 shown in FIG. 3A
45), no defective nozzle is assigned in another pass. Therefore, the use ratio of the defective nozzle when forming the 45th raster is 12.5%.

The use ratio of defective nozzles is the ratio of the number of pixel areas allocated to defective nozzles to the number of pixel areas in which one raster line is formed (the number of pixel areas arranged in the movement direction). For example, the defective nozzle # 29 associated with the 45th raster is an OL nozzle. Therefore, a pixel area that is half of the pixel area that is one of the four horizontal positions is assigned to the defective nozzle # 29. Therefore, the use ratio of the defective nozzle when forming the 45th raster is calculated by the expression “0.5 / 4 × 100 = 12.5%”.

On the other hand, in the upper end process, the medium conveyance amount is relatively small. For this reason, the raster line group to which the defective nozzle group is assigned in a certain pass overlaps the raster line group to which the defective nozzle group is assigned in the previous and subsequent passes. That is, defective nozzles are continuously assigned to the same raster line. Therefore, a plurality of defective nozzles are assigned to the raster line to which the defective nozzles are assigned in the upper end processing pass. For example, as shown in FIG. 3A, two defective nozzles are assigned to the 27th raster (L27), three defective nozzles are assigned to the 28th raster (L28), and 4 are assigned to the 29th raster (L29).
One defective nozzle is assigned.

Therefore, the use ratio of the defective nozzle when forming the 27th raster is 25% (= (0.5 ×
2) / 4 × 100), and the use ratio of the defective nozzle when forming the 28th raster is 37.
. 5% (= (0.5 × 3) / 4 × 100), and the use ratio of defective nozzles when forming the 29th raster is 62.5% (= (0.5 × 3 + 1) / 4 × 100) It becomes.

In the upper end process, not only the defective nozzle group is continuously assigned to the same raster line, but a normal nozzle (open square) may be a defective nozzle as in the 29th raster (L29). is there. A normal nozzle has a larger number of associated pixel regions than an OL nozzle (hatched grid). Therefore, when the normal nozzle that is a defective nozzle is assigned to the raster line, the usage ratio of the defective nozzle is higher than when the OL nozzle that is a defective nozzle is assigned.

In this way, a raster line (for example, L
Compared to 45), the raster line (for example, L27 to 29) to which a defective nozzle is assigned in the upper end processing pass has a higher ratio of defective nozzle use. For example, assuming that the amount of ink ejected from the defective nozzle is smaller than the designed ink ejection amount, the raster line having a high usage ratio of the defective nozzle is a lighter density line than the other raster lines. Therefore, a raster line having a high use ratio of defective nozzles appears as white stripes on the image, and the image quality of the printed image is deteriorated. Further, as the use ratio of defective nozzles increases, the density of the raster line becomes lighter, the raster line becomes more conspicuous on the image, and the image quality of the printed image is further deteriorated.

Similarly, in the lower end process, the medium conveyance amount is relatively small. For this reason, a raster line group to which a defective nozzle group is assigned in a certain pass overlaps a raster line group to which a defective nozzle group is assigned in previous and subsequent passes, and a plurality of defective nozzles are assigned to one raster line. As a result, for example, as shown in FIG. 3B, the usage ratio of defective nozzles when forming the 92nd raster (L92) is 62.5% (= (0.5 × 5) / 4 × 100), and 9
The use ratio of defective nozzles when forming the third raster (L93) is 50% (= (0.5 × 4
) / 4 × 100), and the defective nozzle usage rate when forming the 94th raster (L94) is 37.5% (= (0.5 × 3) / 4 × 100). In the lower end process shown in FIG. 3B, the normal nozzle (outline cell) is not a defective nozzle. However, in the lower end process, the normal nozzle becomes a defective nozzle as in the upper end process. It can be expensive.

Thus, in the upper end process and the lower end process, the medium conveyance amount is shorter than in the normal process, and the usage ratio of defective nozzles in the raster line to which the defective nozzles are assigned in the upper end process and lower end process passes becomes high. A raster line having a high use ratio of defective nozzles has a density different from that of other raster lines, and therefore appears as a streak on the image, resulting in a deterioration in the image quality of the printed image. In addition, as the use ratio of defective nozzles increases, the density difference from other raster lines increases and the image quality deteriorates further. Furthermore, since the medium conveyance amount of the upper end process and the lower end process corresponds to one raster line, a defective nozzle group is continuously assigned to the raster lines arranged in the conveyance direction. That is, raster lines with a relatively high use ratio of defective nozzles are continuously arranged in the transport direction, and the raster line group is conspicuous on the image, and the image quality of the printed image is further deteriorated.

Therefore, the present embodiment aims to suppress the deterioration of the image quality of the printed image even if a defective nozzle group is generated in the nozzle row due to the temporal change of the head 41 (nozzle row).

=== Printing Method of the Present Embodiment ===
FIG. 4A is a diagram for explaining the printing method of the present embodiment for the upper end of the medium, and FIG.
It is a figure explaining the printing method of this embodiment with respect to a medium lower end part. In the printing method of the present embodiment, a medium transport amount (4) that is half of the medium transport amount (8D) of the normal process between the upper end process and the normal process.
D) is provided as an intermediate process (also referred to as an upper end side intermediate process), and an intermediate process (4D) that is a half of the medium transport amount (8D) of the normal process between the lower end process and the normal process (4D) Also called a lower end side intermediate process). As shown in FIG. 4A, passes 1 to 4 are set as upper end processing, passes 5 to 8 are set as upper end side intermediate processing, and passes 9 and after are set as normal processing.
Also, as shown in FIG. 4B, the process up to pass 11 is the normal process, the process from pass 12 to pass 15 is the lower end side intermediate process, and the process from pass 16 to pass 19 is the lower end process. The printing method of the present embodiment and the printing method of the comparative example are the same except that an intermediate process is provided, and the upper end process and the lower end process (edge process) are performed at the edge in the medium transport direction. The normal process is a process of printing an image in the central part (area other than the end part) in the medium transport direction. Further, the medium conveyance amount of the upper end process and the lower end process is short and corresponds to the length of one raster line. Similar to the comparative example, the center portion of the nozzle row (# 29 to # 36) varies with time.
) Is a defective nozzle group.

By providing an intermediate process between the upper end process and the normal process in which the medium conveyance amount is longer than that at the upper end process and shorter than that at the normal process, the nozzles of the intermediate process passes 5 to 8 are mainly allocated. In the raster line, the number of nozzles assigned to each raster line (the number of nozzles arranged in the moving direction) can be increased. For example, in the printing method of the comparative example (FIG. 3A), the number of nozzles assigned to the 27th raster (L27) is 7, whereas in the printing method of the present embodiment (FIG. 3B), the 27th raster (L27). The number of nozzles associated with is nine. Similarly, by providing an intermediate process between the lower end process and the normal process, the medium conveyance amount is longer than that at the lower end process and shorter than that at the normal process, so that the nozzles of the intermediate process passes 12 to 15 are mainly used. In the raster line to which is assigned, the number of nozzles assigned to each raster line can be increased.

In the printing method of the present embodiment, when the number of nozzles assigned to one raster line is eight or more, the nozzles in the subsequent pass are preferentially used for printing on the upper end side than the nozzles in the previous pass. The intermediate processing nozzle has priority over the upper end processing nozzle, and the normal processing nozzle has priority over the intermediate processing nozzle. On the other hand, on the lower end side, the nozzle in the previous pass is used for printing with priority over the nozzle in the subsequent pass, the intermediate processing nozzle is given priority over the lower end processing nozzle, and the normal processing nozzle is used over the intermediate processing nozzle. Takes precedence.

Therefore, in the printing method of the present embodiment (FIG. 4), the number of non-use nozzles can be increased in the upper end processing nozzle row and the lower end processing nozzle row as compared to the comparative printing method (FIG. 3). The number of OL nozzles can be increased (in other words, the number of normal nozzles can be reduced). For example, nozzles # 44 to # 64 are non-use nozzles in pass 1 of the upper end process of the comparative example, whereas nozzles # 28 to # 64 are passed in pass 1 of the upper end process of the present embodiment.
Becomes a non-use nozzle. In the last pass 15 of the lower end process of the comparative example, nozzles # 1 to # 2 are used.
Whereas 8 is a non-use nozzle, nozzles # 1 to # 44 are non-use nozzles in the final pass 19 of the lower end processing of the present embodiment. In the upper end process pass 4 of the comparative example, nozzles # 1 to # 1 are used.
While up to # 32 are normal nozzles (open squares), in the upper end process pass 4 of this embodiment, nozzles # 1 to # 16 are normal nozzles.

As a result, for example, in the comparative example, the defective nozzle group (# 29 to # 36) in the upper end process pass 1 is a nozzle (OL nozzle) used for printing, whereas in this embodiment, the upper end process pass is performed. One defective nozzle group becomes a non-use nozzle. Not only pass 1 but also a part (# 35, # 36) of defective nozzle groups in pass 2 are non-use nozzles. In the comparative example, some of the defective nozzle groups in pass 4 (# 29 to # 32) are normal nozzles, whereas in this embodiment, all defective nozzle groups in pass 4 are OL nozzles. The defective nozzle is OL than the defective nozzle is a normal nozzle.
In the case of a nozzle, the pixel area allocated to the defective nozzle can be reduced, and the usage ratio of the defective nozzle can be reduced.

As described above, in the printing method of the present embodiment, by providing an intermediate process between the upper end process and the normal process, a defective nozzle group that locally occurs in the nozzle row can be changed to a non-use nozzle or an OL.
Or a nozzle. In other words, by providing an intermediate process between the upper end process and the normal process, the usage ratio of the nozzles of the nozzle row belonging to the same head 41 assigned to a certain raster line is changed. As a result, in the printing method of the present embodiment, it is possible to reduce the usage ratio of defective nozzles compared to the printing method of the comparative example.

Specifically, the usage ratio of the defective nozzle of the 27th raster (L27) of the comparative example is 25%, whereas the usage ratio of the defective nozzle of the 27th raster of the present embodiment is 12.5% (= 0
. 5/4 × 100). The usage ratio of the defective nozzle of the 28th raster (L28) of the comparative example is 37.5%, whereas the usage ratio of the defective nozzle of the 28th raster of the present embodiment is 25% (= (0. 5 × 2) / 4 × 100) and the 29th raster (L2) of the comparative example
The usage ratio of the defective nozzle of 9) is 62.5%, whereas the usage ratio of the defective nozzle of the 29th raster in this embodiment is 37.5% (= (0.5 × 3) / 4 ×). 100).

Similarly, by providing an intermediate process between the lower end process and the normal process, for example, in the comparative example, the defective nozzle group in the last pass 15 of the lower end process is a nozzle (OL nozzle) used for printing. In this embodiment, the defective nozzle group in the last pass 19 of the lower end process becomes the unused nozzle. Therefore, in this embodiment, it is possible to reduce the usage ratio of the defective nozzles of the raster line to which the defective nozzle group for the lower end process is assigned. Specifically, the usage ratio of defective nozzles of the 92nd raster (L92) of the comparative example is 62.5%, whereas that of the present embodiment is 92.
The usage ratio of the defective nozzle of the No. raster is 37.5% (= (0.5 × 3) / 4 × 100), and the usage ratio of the defective nozzle of the No. 93 raster (L93) of the comparative example is 50%. On the other hand, the usage ratio of the defective nozzle of the 93th raster of this embodiment is 37.5%, whereas the usage ratio of the defective nozzle of the 94th raster (L94) of the comparative example is 37.5%. The use ratio of defective nozzles of the 94th raster of this embodiment is 25% (= (0.5 × 2) / 4 × 10).
0).

FIG. 5 is a graph showing a difference in the use ratio of defective nozzles in the printing method of the comparative example and the printing method of the present embodiment. The horizontal axis indicates the number of the raster line, and the vertical axis indicates the usage ratio of defective nozzles in each raster line. FIG. 5 shows the usage ratio of defective nozzles in the raster line printed by the upper end process. In the graph, the usage ratio of defective nozzles in the raster line by the printing method of the comparative example is indicated by solid lines and circles (●), and the usage ratio of defective nozzles in the raster lines by the printing method of the present embodiment is indicated by dotted lines and triangles (▲). Show. From this graph, the maximum use ratio (37.5%) of defective nozzles in the printing method of this embodiment is lower than the maximum use ratio (62.5%) of defective nozzles in the printing method of the comparative example. I understand.

Thus, in the printing method of the present embodiment, the maximum use ratio of defective nozzles when forming a raster line can be reduced as compared with the printing method of the comparative example. As a result, it is possible to suppress a raster line having a high use ratio of defective nozzles from appearing as a streak on the image and degrading the image quality of the printed image. Further, in the printing method of the comparative example, a raster line having a relatively high use ratio of defective nozzles (for example, a raster line having a use ratio of defective nozzles of 50% or more) is continuously arranged in the transport direction. In the printing method of the present embodiment, the use ratio of defective nozzles in each raster line can be reduced, so that image quality deterioration can be suppressed.

As described above, in the printing method of the present embodiment, an intermediate process having a medium transport amount shorter than the medium transport amount of the normal process is provided between the upper end process and the normal process and between the lower end process and the normal process. Thus, the number of nozzles assigned to each raster line can be increased, and the number of unused nozzles can be increased in the nozzle rows for the upper end process and the lower end process. As a result, in the printing method of the present embodiment, the maximum use ratio of defective nozzles when forming a raster line can be reduced as compared with the printing method of the comparative example.

However, if the medium transport amount in the intermediate process is made too short, the raster line group to which the defective nozzle group is assigned in the pass with the intermediate process and the defective nozzle group in the passes before and after the upper end process and the lower end process. The raster line group to which is assigned overlaps greatly. As a result, the number of defective nozzles assigned to each raster line increases. In other words, the overlap rate of the raster line group to which the defective nozzle group is assigned in the pass before and after the intermediate process is reduced by making the medium transfer amount of the intermediate process longer than the medium transfer amount of the upper end / lower end process. And the number of defective nozzles assigned to each raster line can be reduced.

Therefore, the medium transport amount of the intermediate process is set to half (1/2) of the medium transport amount of the normal process so as not to be too short and not too long. That is, the controller 10 (control unit) of the printer 1 of the present embodiment uses a nozzle row belonging to one head 41 and is longer than the medium conveyance amount of the end process between the upper end / lower end process and the normal process. An image is printed on the medium by performing a printing method provided with an intermediate process that is a medium transport amount that is half the medium transport amount of the normal process. By doing so, as shown in FIG. 4, overlapping of raster line groups to which defective nozzle groups are assigned in the pass before and after the intermediate process while the defective nozzles generated in the nozzle rows of the upper end process and the lower end process are made non-use nozzles The rate can be reduced. As a result, even when defective nozzles are locally generated in the nozzle row belonging to one head 41 due to a change over time, the printing method according to the present embodiment is more effective in forming a raster line than the printing method of the comparative example. It is possible to reduce the maximum use ratio of defective nozzles and to suppress image quality deterioration of a printed image.

In particular, as in the printing method of the present embodiment (FIG. 4), when the medium transport amount of the upper end process and the lower end process is short and corresponds to the length of one raster line, it is continuous with the raster line aligned in the transport direction. A defective nozzle is assigned. Therefore, the number of defective nozzles assigned to one raster line increases. Therefore, by providing the intermediate process, an effect of reducing the use ratio of defective nozzles in each raster line can be further obtained.

In FIG. 4, a printing method in which an intermediate process is provided between the upper end process and the normal process and between the normal process and the lower end process is taken as an example, but the present invention is not limited thereto. For example, a printing method in which an intermediate process is provided only in any one of the upper end process and the normal process and between the normal process and the lower end process may be used. Even in such a printing method, it is possible to suppress deterioration in image quality at one end of the printed image.

=== Verification result of medium transport amount in intermediate processing ===
In the printing method shown in FIG. 4, the number of defective nozzles generated in the nozzle row due to changes over time is set to 8, and the number of passes for intermediate processing is set to 4. Hereinafter, not only the printing conditions but also other printing conditions will be shown verification results as to whether it is effective that the medium transport amount of the intermediate process is half of the medium transport amount of the normal process. For this purpose, the medium conveyance amount of the intermediate process is varied variously under other printing conditions, and the use ratio of defective nozzles when forming each raster line is calculated. Note that, as shown in FIG. 4, the operation by providing the intermediate process between the upper end process and the normal process is the same as the operation by providing the intermediate process between the lower end process and the normal process. Therefore, in the following, for the sake of simplicity of explanation, a case where an intermediate process is provided between the upper end process and the normal process will be described as an example.

FIG. 6A is a graph showing the usage ratio of defective nozzles when the number of defective nozzles generated due to changes over time is four, and FIG. 6B shows the usage ratio of defective nozzles when the number of defective nozzles is eight. FIG. 6C is a graph showing the usage ratio of defective nozzles when the number of defective nozzles is 16. The horizontal axis indicates the raster line number, and the vertical axis indicates the usage ratio of defective nozzles. Note that the number of passes for intermediate processing is four, and the total number of passes for top processing and the number of passes for intermediate processing is the number of passes for one cycle. The number of passes for one cycle is the number of passes in which dots are formed to complete one raster line in normal processing. In the normal process, one raster line is completed by eight OL nozzles. That is, 4
It is assumed that dots are formed by two nozzles for a pixel region classified into each of the two horizontal positions. The medium transport amount for normal processing corresponds to the length of eight raster lines, and the medium transport amount for upper end / lower end processing corresponds to the length of one raster line. Assume that the number of nozzles belonging to the nozzle row is 64, and a defective nozzle is generated at the center. In FIG.
In FIG. 6B, eight nozzles # 29 to # 36 are defined as defective nozzles, and in FIG. 6C, sixteen nozzles # 25 to # 40 are defined as defective nozzles.

In each graph, the calculation result (circle (◯) / dotted line) of the defective nozzle use ratio in the printing method of the comparative example in which no intermediate processing is provided, and the medium transport amount (7) of the intermediate processing are the media of the normal processing Calculation results (square (■), solid line) of the defective nozzle usage rate when the length of one raster line is shorter than the transport amount (8, normal feed amount), and the intermediate processing medium transport amount (4 ) Is a half of the medium transport amount (8) of the normal processing, the calculation result of the defective nozzle usage rate (triangle (▲
) And solid line), and the media transport amount for intermediate processing (2) is the media transport amount for top processing (1 and top feed amount)
The calculation result of the defective nozzle usage ratio when the length of one raster line is longer than (
X (solid line) is shown. However, in the graph of FIG. 6C, in order to make the result easy to see, the result of the printing method of the comparative example is excluded.

When the number of defective nozzles is four, as shown in the graph of FIG. 6A, when the medium conveyance amount of the intermediate process is longer by one raster line than the medium conveyance amount of the upper end process (×), The maximum use ratio of defective nozzles when forming a raster line is the lowest, and image quality deterioration can be suppressed most.
When the number of defective nozzles is 8, as shown in the graph of FIG. 6B, when the raster line is formed when the medium transport amount of the intermediate process is half of the medium transport amount of the normal process (▲). The maximum use ratio of defective nozzles is the lowest, and image quality deterioration can be suppressed most.
When the number of defective nozzles is 16, as shown in the graph of FIG. 6C, the maximum use ratio of defective nozzles in all medium transport amounts is the same. However, when the medium transport amount of the intermediate process is half of the medium transport amount of the normal process (▲), the number of raster lines that maximizes the use ratio of defective nozzles is the smallest. The smaller the number of raster lines at which the defective nozzle usage ratio is maximum, the smaller the number of raster lines appearing as streaks on the image.
Therefore, when the medium transport amount of the intermediate process is half of the medium transport amount of the normal process, the image quality deterioration can be suppressed most.

As a result, when the number of defective nozzles is four, the medium conveyance amount of the intermediate process is further shorter than half (4) of the medium conveyance amount of the normal process, and one raster line is larger than the medium conveyance amount of the upper end process. When it is longer by (2), image quality degradation can be suppressed most. On the other hand, when the number of defective nozzles is 8 or 16, the image quality degradation can be suppressed most when the medium transport amount of the intermediate process is half (4) of the medium transport amount of the normal process. This is because when the number of defective nozzles is small, the raster line groups to which the defective nozzle groups are assigned in the passes before and after the intermediate process are difficult to overlap even if the medium conveyance amount of the intermediate process is short.

FIG. 7A is a graph showing the usage ratio of defective nozzles when the number of passes of intermediate processing is three passes, and FIG. 7B shows the usage ratio of defective nozzles when the number of passes of intermediate processing is two passes. FIG. 7C is a graph showing a defective nozzle usage ratio when the number of passes of the intermediate process is one pass. Note that it is assumed that four defective nozzles (# 31 to # 34) are generated at the center of the nozzle row, and the medium conveyance amount in the upper end / lower end processing corresponds to the length of one raster line.

If the total number of passes of the upper end process and the number of passes of the intermediate process is set to the number of passes for one cycle, the medium transport amount of the normal process differs depending on the number of passes of the intermediate process. When the number of passes of the intermediate processing is 3 passes, the medium transport amount of the normal processing is equivalent to the length of 9 raster lines, and one raster line has 6 OL nozzles and 1 normal during normal processing. It is formed with a nozzle. When the number of passes of the intermediate processing is two passes, the medium transport amount of the normal processing corresponds to the length of 10 raster lines, and one raster line has four OL nozzles and two normal processing during normal processing. It is formed with a nozzle. When the number of passes of the intermediate processing is one pass, the medium transport amount of the normal processing is equivalent to the length of 12 raster lines, and one raster line has two OL nozzles and three normal processing during normal processing. It is formed with a nozzle.

When the number of passes for intermediate processing is 3, as shown in the graph of FIG. 7A, a raster line is formed when the medium transport amount for intermediate processing is half the medium transport amount for normal processing (▲). In this case, the maximum use ratio of defective nozzles is the lowest, and image quality deterioration can be suppressed. Similarly, when the number of passes for intermediate processing is two passes (FIG. 7B) and when the number of passes for intermediate processing is one pass (FIG. 7C), the medium transport amount for intermediate processing is the medium transport amount for normal processing. If it is half of (▲),
The maximum use ratio of defective nozzles is the lowest, and image quality deterioration can be suppressed.

As shown in FIG. 6A described above, when the number of passes of the intermediate process is 4 and the number of defective nozzles is as small as 4, the medium transport amount of the intermediate process is even shorter than half of the medium transport amount of the normal process, and the upper end process is performed. When it is longer than the medium transport amount by one raster line, the maximum use ratio of defective nozzles can be made the lowest. On the other hand, as shown in FIG. 7A to FIG. 7C, even when the number of defective nozzles is as small as four, if the number of passes of the intermediate process is changed (if the number of passes of the intermediate process is reduced), When the medium transport amount of the intermediate process is half of the medium transport amount of the normal process, the maximum use ratio of the defective nozzle can be minimized. This is because if the number of passes in the intermediate process decreases, the number of nozzles that can be made non-use nozzles in the upper end process pass decreases, and the effect of shortening the medium transport amount in the intermediate process, that is, a raster to which a defective nozzle group is assigned. This is because the line group is greatly affected by an increase in the number of defective nozzles assigned to each raster line. If the number of passes for intermediate processing is increased too much, nozzles for intermediate processing are assigned to the raster line upstream of the raster line group to which the defective nozzle group is assigned in the upper end processing, thereby reducing the use ratio of defective nozzles. Cannot be obtained.

In summary, when the number of passes of the intermediate process is 4 (FIGS. 6A to 6C), if the number of defective nozzles is relatively large (for example, a raster line corresponding to the medium transport amount of the normal process is formed). When the number of nozzles (eight or more) is half of the medium transport amount of the intermediate process, image quality deterioration can be suppressed, and when the number of defective nozzles is relatively small (four nozzles) ),
Image degradation can be suppressed when the medium transport amount of the intermediate process is further shorter than half of the medium transport amount of the normal process. However, if the number of passes for intermediate processing is different (if the number of passes for intermediate processing is reduced), even if the number of defective nozzles is relatively small (four), the amount of medium transport for intermediate processing is the amount of medium transport for normal processing. Image quality degradation can be suppressed.

As a result of the above, if the media transport amount for intermediate processing is half of the media transport amount for normal processing, the maximum usage ratio of defective nozzles is the lowest or the usage ratio of defective nozzles is the maximum usage ratio under more printing conditions. The number of raster lines is the smallest and image quality deterioration can be suppressed. Further, when the number of passes of the intermediate process is 4 and the number of defective nozzles is as small as 4 (FIG. 6A).
), The maximum use ratio of the defective nozzle is the second lowest when the medium transport amount of the intermediate process is half of the medium transport amount of the normal process. Therefore, the printer 1 of the present embodiment implements a printing method in which an intermediate process that is a medium transport amount that is half the medium transport amount of the normal process is provided between the upper end process and the normal process. By doing so, image quality degradation can be suppressed under more printing conditions.

FIG. 8 is a graph showing the usage ratio of the defective nozzle to the lower end side of the medium. Note that the number of passes of the intermediate process between the normal process and the lower end process is 4 passes, and among the 64 nozzles belonging to the nozzle row, the central 8 nozzles (# 29 to # 36) are defective nozzles. That is, it is a graph under the same printing conditions as in FIG. 6B. Also in FIG. 8, when the medium transport amount of the intermediate process is half of the medium transport amount of the normal process (A), the maximum use ratio of the defective nozzle is the lowest.
Moreover, the result of the usage ratio of each conveyance amount shown in FIG. 8 and the result of the usage ratio of each conveyance amount shown in FIG. 6B are symmetrical with respect to the vertical axis. Also from this, it can be said that the operation by providing the intermediate process between the upper end process and the normal process is the same as the operation by providing the intermediate process between the lower end process and the normal process. Therefore, in the intermediate process between the lower end process and the normal process, as in the intermediate process between the upper end process and the normal process, more media can be printed by reducing the medium transport amount to half the normal process medium transport amount. It can be said that image quality deterioration can be suppressed under the conditions. Therefore, the printer 1 of the present embodiment implements a printing method in which an intermediate process that is a medium transport amount that is half the medium transport amount of the normal process is provided between the lower end process and the normal process. By doing so, image quality degradation can be suppressed under more printing conditions.

FIG. 9A is a diagram for explaining a printing method when the medium conveyance amount in the intermediate processing is discarded.
FIG. 7B is a diagram illustrating a printing method when the medium conveyance amount of intermediate processing is rounded up. Figure 4 above
In the printing method shown in FIG. 4, since the number of raster lines corresponding to the medium transport amount for normal processing is an even number (8), the intermediate processing medium transport amount that is half of the medium transport amount for normal processing is used. The corresponding number of raster lines (4) is an integer. However, the present invention is not limited to this, and as shown in FIG. 9, the number of raster lines corresponding to the medium conveyance amount of the normal processing may be an odd number (9, corresponding to the first number).

In this case, since the number of raster lines corresponding to half of the medium transport amount of the normal process is “4.5”, the decimal part is rounded down as shown in FIG. 9A to correspond to the medium transport amount (4D) of the intermediate process. The number of raster lines to be set may be “4”, or may be rounded up as shown in FIG. 9B to set the number of raster lines corresponding to the medium transport amount (5D) of the intermediate process to “5”. That is, an integer part “4” of a value 4.5 obtained by dividing the number of raster lines corresponding to the medium conveyance amount of the intermediate processing by the number of raster lines “9” corresponding to the medium conveyance amount of the normal processing by 2, or 4 A value “5” obtained by adding 1 to may be used. In either case, as shown in FIG. 9, it is possible to reduce the overlap rate of the raster line group to which the defective nozzle group is assigned in the intermediate process while making some of the defective nozzles in the upper end process non-use nozzles. ing. The number of raster lines corresponding to the medium transport amount of the intermediate process is the number of raster lines aligned in the transport direction in the area on the medium whose length in the transport direction corresponds to the length of the medium transport amount of the intermediate process. That is.

FIG. 10A is a graph showing a use ratio of defective nozzles when eight defective nozzles are generated at the center of the nozzle row as shown in FIG. The graph shows the result of calculation of defective nozzle usage ratio (circle (●) / dotted line) in the printing method of the comparative example without intermediate processing, and the usage of defective nozzles when half of the media transport amount of normal processing is cut off. Ratio calculation result (square (■), solid line)
Calculation result of defective nozzle usage rate when half of the media transport amount of normal processing is rounded up (triangle (
▲) and solid line) are shown. From this graph, compared to the printing method of the comparative example, the printing method provided with an intermediate process in which the medium conveyance amount is half of the medium conveyance amount of the normal process (rounded down or rounded up) has a maximum use ratio of defective nozzles. It turns out that it is low. Also, when half the normal processing medium transport amount is rounded down to the intermediate processing medium transport amount (■), half the normal processing medium transport amount is rounded up to the intermediate processing medium transport amount. In this case (▲), it can be seen that the maximum use ratio of the defective nozzles is the same, and image quality deterioration can be suppressed to the same extent.

FIG. 10B is a graph showing a use ratio of defective nozzles when four defective nozzles are generated at the center of the nozzle row in the printing method shown in FIG. 9. In this case, when half the normal processing medium transport amount is rounded down to the intermediate processing medium transport amount (■), half the normal processing medium transport amount is rounded up to the intermediate processing medium transport amount. The maximum use ratio of defective nozzles can be made lower than when the amount is set (▲). Therefore, in this case, image quality deterioration can be further suppressed by setting a value obtained by discarding half of the medium transport amount of the normal process to the medium transport amount of the intermediate process.

FIG. 11A and FIG. 11B are diagrams illustrating the usage ratio of defective nozzles when defective nozzles are generated at the ends. Up to this point, the case where a defective nozzle is generated at the center of the nozzle row is taken as an example, but the present invention is not limited to this. In FIG. 11, eight nozzles (# 1 to # 8) at the downstream end of the nozzle row in the transport direction are defined as defective nozzles. FIG. 11A shows a printing method of a comparative example in which no intermediate process is provided between the upper end process and the normal process, and FIG. 11B shows a half of the medium transport amount (8D) of the normal process between the upper end process and the normal process. The printing method of this embodiment which provided the intermediate process which is medium conveyance amount (4D) is shown.

By providing the intermediate process, as shown in FIG. 11B, the nozzle on the upstream side in the transport direction with respect to the nozzle # 29 in the pass 1 of the upper end process can be changed to a non-use nozzle. However, here, since it is assumed that a defective nozzle is generated at the end of the nozzle row, the defective nozzle in the upper end processing pass cannot be changed to a non-use nozzle. Therefore, the maximum use ratio (100% of L1 to L5) of defective nozzles in the printing method of this embodiment (FIG. 11B) and the printing method of the comparative example (FIG. 11A).
The maximum use ratio of defective nozzles at L is equal to 100% of L1 to L5.

FIG. 12A and FIG. 12B are diagrams illustrating the usage ratio of defective nozzles when defective nozzles are generated between the end portion and the central portion. FIG. 12 shows an example in which eight defective nozzles (# 13 to # 20) are generated between the end (nozzle # 1) and the center (nozzle # 32) of the nozzle row. FIG. 12A shows a printing method of a comparative example in which no intermediate process is provided, and FIG. 12B shows an embodiment in which an intermediate process having a medium transport amount (4D) that is half the medium transport amount (8D) of the normal process is provided. The printing method is shown.

Similarly to FIG. 11 described above, by providing the intermediate process, as shown in FIG. 12B, the nozzle on the upstream side in the transport direction from the nozzle # 29 in pass 1 of the upper end process can be changed to a non-use nozzle. However, here, since it is assumed that defective nozzles (# 13 to # 20) are generated between the end portion and the central portion of the nozzle row, the defective nozzles in the upper end processing pass cannot be used.

However, by providing the intermediate process, as shown in FIG. 12B, in the raster line group (L10 to L20) to which the defective nozzle group for the upper end process is allocated, the number of nozzles allocated to each raster line can be increased. Therefore, the raster line group (L10 to L20
OL nozzles (hatched cells) assigned to () can be increased. As a result, in the printing method of the comparative example (FIG. 12A), the defective nozzle is a normal nozzle (white squares), whereas in the printing method of this embodiment (FIG. 12B), the defective nozzle is an OL nozzle. (Hatched cells). For example, in FIG. 12A, six of the eight defective nozzles in pass 2 are normal nozzles, whereas in FIG. 12B, all eight defective nozzles in pass 2 are OL.
Nozzle. The number of pixel areas associated with the OL nozzle is smaller than that of the normal nozzle. Therefore, the maximum use ratio of defective nozzles in the printing method of the comparative example (87 of L13 to L16).
. 5%), the maximum use ratio (L13 to L) of defective nozzles in the printing method of this embodiment.
17 (62.5%) can be reduced, and image quality deterioration can be suppressed.

In other words, if a defective nozzle occurs outside the end of the nozzle row, an intermediate process, which is a medium transport amount that is half the medium transport amount of the normal process, is provided between the end process and the normal process. A non-use nozzle can be used, or a defective nozzle can be an OL nozzle. As a result, the maximum usage ratio of defective nozzles when forming a raster line can be reduced, and image quality deterioration can be suppressed.

=== Other Embodiments ===
Each of the above embodiments is described mainly for a printing system having an ink jet printer, but includes disclosure of a printing method and the like. The above-described embodiments are for facilitating understanding of the present invention, and are not intended to limit the present invention. The present invention can be changed and improved without departing from the gist thereof, and it is needless to say that the present invention includes equivalents thereof. In particular, the embodiments described below are also included in the present invention.

<About the printer>
In the above-described embodiment, a printer that repeats the operation of forming an image on a cut sheet while moving the head 41 in the movement direction and the operation of conveying the cut sheet in the conveyance direction with respect to the head 41 is taken as an example. However, it is not limited to this. For example, for continuous paper transported to the printing area,
A printer that forms an image by repeating the operation of forming an image while moving the head in the medium conveyance direction and the operation of moving the head in the paper width direction, and then conveys an unprinted medium portion to the printing area. But you can.

1 Printer, 10 Controller, 11 Interface section,
12 CPU, 13 memory, 14 unit control circuit,
20 transport unit, 30 carriage unit, 31 carriage,
40 head units, 41 heads,
50 detector groups, 60 computers

Claims (4)

(A) a nozzle row in which nozzles for ejecting fluid to the medium are arranged in a predetermined direction;
(B) an image forming operation in which fluid is ejected from the nozzles while relatively moving the medium and the nozzle row in a direction intersecting the predetermined direction, and the relative position of the medium with respect to the nozzle row is one in the predetermined direction. A control unit that repeatedly executes the movement in the direction,
A normal process for forming an image at a central portion in the predetermined direction of the medium, and an end process for forming an image at an end portion in the predetermined direction of the medium, in the predetermined direction of the medium with respect to the nozzle row The relative movement amount is longer than the relative movement amount of the end processing and the end processing is shorter than the relative processing amount of the normal processing. A control unit that forms an image on the medium by performing an intermediate process that is half of the relative movement amount;
A fluid ejecting apparatus comprising (C). The fluid ejection device according to claim 1,
The nozzle row is the nozzle row belonging to one head.
Fluid ejection device. The fluid ejecting apparatus according to claim 1 or 2,
When the first number that is the number of dot rows along the intersecting direction corresponding to the relative movement amount of the normal processing is an odd number,
The number of dot rows corresponding to the relative movement amount of the intermediate process is
The integer part of the value obtained by dividing the first number by 2 or the number obtained by adding 1 to the integer part,
Fluid ejection device. An image forming operation for ejecting fluid from the nozzle while relatively moving a nozzle row and a medium in which nozzles for ejecting fluid are arranged in a predetermined direction in a direction intersecting the predetermined direction, and a relative position of the medium with respect to the nozzle row An operation of moving the predetermined direction in one direction is a fluid ejection method in which the operation is repeated,
A normal process for forming an image at a central portion in the predetermined direction of the medium, and an end process for forming an image at an end portion in the predetermined direction of the medium, in the predetermined direction of the medium with respect to the nozzle row The relative movement amount is longer than the relative movement amount of the end processing and the end processing is shorter than the relative processing amount of the normal processing. A fluid ejection method, wherein an intermediate process that is half of the relative movement amount is performed.

Images