JP5874182B2 - Printing apparatus, printing method, and computer program - Google Patents

Description

  The present invention relates to printing that forms an image on a printing medium by ejecting ink.

  2. Description of the Related Art In recent years, printing apparatuses that print images by ejecting ink from nozzles provided in a print head while performing main scanning that reciprocates the print head to form ink dots on a print medium have become widespread. In such a printing apparatus, an achromatic color nozzle row that discharges achromatic color ink (for example, black ink) and a chromatic color nozzle row that discharges chromatic color ink (for example, cyan ink, magenta ink, and yellow ink) are used. A technique for forming a color region including a chromatic color in a print image and forming a monochrome region not including a chromatic color in the print image using only the achromatic color nozzle array is disclosed (for example, see Patent Document 1).

JP 2006-231930 A

  The conventional technology described above has room for improvement in terms of both improving the printing image quality and suppressing the increase in time required for the printing process. In particular, in the above-described conventional technique, the printing image quality is improved by suppressing the positional deviation along the main scanning direction of a line substantially parallel to the conveyance direction (sub-scanning direction) of the printing medium formed using the achromatic ink. In addition, there is room for improvement in terms of coexistence of the increase in time required for the printing process.

  SUMMARY An advantage of some aspects of the invention is to solve the above-described problem and perform printing while suppressing an increase in time required for printing processing when performing printing processing for forming an image on a printing medium by ejecting ink. The purpose is to improve image quality.

In order to solve at least a part of the above problems, the present invention can be realized as the following forms or application examples. A printing apparatus, a chromatic color nozzle row configured by K (K is an integer of 2 or more) nozzles that discharge chromatic color inks arranged along a first direction, and along the first direction And an achromatic nozzle row composed of (n · K) (n is an integer of 2 or more) nozzles that discharge achromatic ink arranged side by side, and a second direction that intersects the first direction A plurality of nozzle rows arranged side by side, a moving mechanism for reciprocally moving the plurality of nozzle rows relative to the print medium along the second direction, and the print medium as the plurality of print media. A transport mechanism that transports relative to the nozzle row along the first direction, and based on print data, the moving mechanism moves the plurality of nozzle rows in the forward and backward directions while moving Image forming operation for ejecting ink to a plurality of nozzle rows, and A control unit that forms an image on the print medium by repeating a transport operation that transports the print medium to the transport mechanism, and the control unit includes the plurality of the color regions including chromatic colors in the image. In the image forming operation of m times (m is an integer not less than 1 and not more than n) in which the movement direction of the plurality of nozzle rows is alternately switched between the forward direction and the backward direction, the movement direction of the plurality of nozzle rows is the forward direction. Only one image forming operation in which the chromatic color nozzle row and the achromatic color nozzle row are used in a specific direction which is one of the backward direction and only the chromatic color nozzle row is used (m− 1) forming a region having a predetermined width along the first direction of the image by m times of the image forming operations including the image forming operations, and in a monochrome region not including a chromatic color in the image, Above The region of the predetermined width of the image is formed by one image forming operation in which only a chromatic nozzle row is used, and the control unit uses each nozzle in each image forming operation based on image data representing an image. A print data generation unit configured to generate the print data specifying an ink discharge mode; and the printing apparatus further includes a position along the first direction of each nozzle in each of the image forming operations, an ink discharge mode, and A storage unit that stores a scheduling table having a capacity corresponding to the (n · K) nozzles constituting the achromatic nozzle row, and the print data generation unit includes: Using the scheduling table sharing the structure, the print data for the chromatic nozzle row and the achromatic color nozzle A printing apparatus that generates the print data for a string. In addition, the present invention can be realized as the following forms or application examples.

Application Example 1 A printing apparatus,
A chromatic color nozzle array composed of K (K is an integer of 2 or more) nozzles that discharge chromatic color inks aligned along the first direction, and achromatic color ink aligned along the first direction And an achromatic nozzle array composed of (n · K) nozzles (n is an integer of 2 or more), and arranged side by side along a second direction intersecting the first direction A plurality of nozzle rows,
A moving mechanism for reciprocally moving the plurality of nozzle rows relative to the print medium along the second direction;
A transport mechanism that transports the print medium relative to the plurality of nozzle rows along the first direction;
Based on the print data, an image forming operation for causing the moving mechanism to move the plurality of nozzle rows in the forward and backward directions and ejecting ink to the plurality of nozzle rows; and A controller that forms an image on the print medium by repeating the transport operation to transport,
In the color region including the chromatic color in the image, the control unit performs m times (m is an integer of 1 to n) in which the moving direction of the plurality of nozzle rows is alternately switched between the forward direction and the backward direction. One time in which the moving direction of the plurality of nozzle rows is a specific direction that is one of the forward direction and the backward direction, and both the chromatic color nozzle row and the achromatic color nozzle row are used. A predetermined width along the first direction of the image by m times of the image forming operation including the image forming operation of (m−1) times and only the image forming operation of (m−1) times in which only the chromatic color nozzle row is used. In a monochrome region that does not include a chromatic color in the image, the region of the predetermined width of the image is formed by one image forming operation in which only the achromatic nozzle row is used,
The control unit includes a print data generation unit that generates the print data for specifying an ink discharge mode by each nozzle in each image forming operation based on image data representing an image,
The printing apparatus is a scheduling table that records a position along the first direction of each nozzle and an ink discharge mode in each image forming operation, and configures the achromatic nozzle row (n K) comprising a storage unit for storing a scheduling table having a capacity corresponding to the nozzles;
The printing apparatus, wherein the print data generation unit generates the print data for the chromatic color nozzle row and the print data for the achromatic color nozzle row by using the scheduling table in common.

  In this printing apparatus, the image forming operation in which the achromatic nozzle row is used in the color region is all in the same direction. Therefore, the ruled line substantially parallel to the first direction formed using the achromatic ink is used. Occurrence of misalignment along the second direction can be suppressed, and the print image quality can be improved. Further, in this printing apparatus, the number of nozzles constituting the achromatic color nozzle row is n times the number of nozzles constituting the chromatic color nozzle row, and in the color region, the chromatic color nozzle row and the achromatic color nozzle row A region having a predetermined width along the first direction of the image is formed by one image forming operation in which both are used and (m−1) image forming operations in which only the chromatic color nozzle row is used. Therefore, it is possible to suppress an increase in the time required for the printing process while setting the direction of the image forming operation in which the achromatic nozzle row is used to be the same direction. Therefore, in this printing apparatus, it is possible to improve the print image quality while suppressing an increase in time required for the printing process. Further, in this printing apparatus, the scheduling table has a capacity corresponding to (n · K) nozzles constituting the achromatic nozzle row, and the print data generation unit uses the scheduling table in common and uses the chromatic color nozzle. Since the print data for columns and the print data for achromatic nozzle rows are generated, the capacity of the storage unit for storing the scheduling table can be reduced.

[Application Example 2] The printing apparatus according to Application Example 1,
When the print data generation unit generates the print data for the color area, each of the print resolutions along the first direction of the image forming operation of each achromatic color nozzle subgroup has each of the existence. The (n · K) number of nozzles constituting the achromatic nozzle row are set to be equal to the printing resolution along the first direction of the m image forming operations of the chromatic nozzle row. Grouping into chromatic nozzle subgroups, and generating the print data for the chromatic nozzle row and the print data for each achromatic nozzle subgroup in a common way,
The printing apparatus, wherein the scheduling table has a capacity corresponding to a nozzle constituting each of the achromatic nozzle subgroups.

  In this printing apparatus, in this printing apparatus, when the print data generation unit generates the print data for the color area, the printing along the first direction of one image forming operation of each achromatic nozzle subgroup is performed. A plurality of (n · K) nozzles constituting the achromatic nozzle row are arranged so that the resolution is the same as the printing resolution along the first direction of m image forming operations of each chromatic nozzle row. Grouped into chromatic nozzle subgroups, print data for chromatic nozzle rows and print data for each achromatic nozzle subgroup are generated in a common way, speeding up printing processing and reducing required memory capacity Can be realized. Further, in this printing apparatus, the capacity of the scheduling table can be set to a capacity corresponding to the nozzles constituting each achromatic nozzle subgroup, so that the capacity of the storage unit for storing the scheduling table can be further reduced. it can.

[Application Example 3] The printing apparatus according to Application Example 2,
The print data generation unit includes (n · K) nozzles constituting the achromatic nozzle row, and n / m achromatic nozzle subs each including (m · K) nozzles. Printing devices that are grouped into groups.

  In this printing apparatus, the print data generation unit includes (n · K) nozzles constituting the achromatic nozzle row and n / m achromatic nozzle subs each including (m · K) nozzles. In order to divide into groups, the print resolution along the first direction of one image forming operation of each achromatic nozzle subgroup is along the first direction of m image forming operations of each chromatic nozzle row. Can be grouped to the same print resolution, speeding up the printing process, reducing the required memory capacity, and further reducing the storage capacity for storing the scheduling table can do.

[Application Example 4] The printing apparatus according to any one of Application Example 1 to Application Example 3,
The control unit performs the first image forming operation in which the moving direction of the plurality of nozzle rows is the specific direction among the m times of image forming operations, between the chromatic color nozzle row and the achromatic color nozzle row. A printing apparatus that performs the image forming operation once in which both are used.

  In this printing apparatus, an image in which both the chromatic color nozzle row and the achromatic color nozzle row are used for the first image forming operation in which the movement direction of the plurality of nozzle rows is a specific direction among the m times of image forming operations. Since this is a forming operation, the achromatic nozzle array is used when the amount of ink on the print medium is relatively small and the deflection of the print medium is small, and the occurrence of ruled line position displacement can be effectively suppressed. it can.

[Application Example 5] The printing apparatus according to any one of Application Example 1 to Application Example 4,
The printing apparatus, wherein the value of n is an even number.

  In this printing apparatus, it is possible to increase the speed by simplifying the processing.

  Note that the present invention can be realized in various modes. For example, the printing method and the printing apparatus, the control method and the control apparatus for the printing apparatus, the printing system, and the functions of these methods, the apparatus, and the system are realized. For example, a recording medium on which the computer program is recorded, a data signal that includes the computer program and is embodied in a carrier wave, and the like.

1 is a schematic configuration diagram of a printing system according to a first embodiment of the present invention. FIG. 2 is a block diagram illustrating a configuration of the ink jet printer 20 with a control circuit 40 as a center in the first embodiment. It is explanatory drawing which shows arrangement | positioning of the nozzle provided in the print head 28 of the inkjet printer 20 in 1st Example. 4 is a flowchart showing a flow of printing processing by the inkjet printer 20. It is explanatory drawing which shows an example of the recording method in the printing process by the inkjet printer 20 of 1st Example. It is explanatory drawing which shows another example of the recording method in the printing process by the inkjet printer 20 of 1st Example. It is explanatory drawing which shows an example of the recording method in the printing process by the inkjet printer 20 of 1st Example. It is explanatory drawing which shows an example of the recording method in the printing process by the inkjet printer 20 of 1st Example. It is explanatory drawing which shows an example of the recording method which considered grouping of the nozzle row for black. It is explanatory drawing which shows arrangement | positioning of the nozzle provided in the print head 28a of the inkjet printer 20 in 2nd Example. It is explanatory drawing which shows an example of the recording method in the printing process by the inkjet printer 20 of 2nd Example. It is explanatory drawing which shows an example of the recording method in the printing process by the inkjet printer 20 of 3rd Example. It is explanatory drawing which shows an example of the recording method in the printing process by the inkjet printer 20 of 3rd Example. It is explanatory drawing which shows an example of a scheduling table. It is explanatory drawing which shows an example of a scheduling table. It is explanatory drawing which shows an example of the recording method in the printing process by the inkjet printer 20 of 4th Example. It is explanatory drawing which shows an example of a virtual scheduling table. It is explanatory drawing which shows an example of a virtual scheduling table.

Next, embodiments of the present invention will be described in the following order based on examples.
A. First embodiment:
A-1. Configuration of printing device:
A-2. Printing process:
B. Second embodiment:
C. Third embodiment:
D. Fourth embodiment:
E. Variations:

A. First embodiment:
A-1. Configuration of printing device:
FIG. 1 is a schematic configuration diagram of a printing system according to a first embodiment of the present invention. The printing system according to the first embodiment includes an inkjet printer 20 and a computer 88 that supplies an image data ID representing an image to the inkjet printer 20. The ink jet printer 20 is connected to a computer 88 via a connector 56.

  On the computer 88, an application program that handles images operates under a predetermined operating system. When the computer 88 receives an image print instruction via the mouse or keyboard, the application program outputs the image data ID via the operating system. The image data ID is, for example, RGB data indicating the gradation value of each pixel in the RGB color space.

  The ink jet printer 20 includes a moving mechanism that performs main scanning for reciprocating the carriage 30 along a direction parallel to the axis of the platen 26, and a sheet P as a printing medium in a direction (sub scanning direction) that intersects the main scanning direction. A transport mechanism that performs the sub-scan to be transported, a print head unit 60 mounted on the carriage 30, and a control circuit 40 that controls print processing by the inkjet printer 20 are provided.

  The transport mechanism that transports the paper P includes a paper feed motor 22 and a gear train (not shown) that transmits the rotation of the paper feed motor 22 to a paper transport roller (not shown). The rotation of the paper feed motor 22 is transmitted to the paper transport roller, and the paper P is transported by the rotation of the paper transport roller. The moving mechanism for reciprocating the carriage 30 is endless between the carriage motor 24, the carriage motor 24, a sliding shaft 34 that is laid in parallel to the axis of the platen 26, and slidably holds the carriage 30. A pulley 38 that stretches the drive belt 36 and a position detection sensor 39 that detects the origin position of the carriage 30 are included. The rotation of the carriage motor 24 is transmitted to the carriage 30 via the drive belt 36, whereby the carriage 30 reciprocates along the sliding shaft 34. The direction parallel to the main scanning direction corresponds to the second direction in the present invention, and the direction parallel to the sub-scanning direction corresponds to the first direction in the present invention.

  FIG. 2 is a block diagram showing the configuration of the ink jet printer 20 centering on the control circuit 40 in the first embodiment. The control circuit 40 includes a CPU 41 and an internal memory 43. The internal memory 43 stores a printer driver 45 that is a computer program for controlling the inkjet printer 20. The printer driver 45 is a module that generates print data that specifies the ink discharge mode (ink discharge / non-discharge or ink discharge amount) by each nozzle in each image forming operation based on the image data ID. Part 47 is included. The CPU 41 functions as a control unit that controls the inkjet printer 20 by reading and executing the printer driver 45 stored in the internal memory 43.

  The control circuit 40 further includes an I / F dedicated circuit 50 that is an interface with an external motor, a head drive circuit 52 that is connected to the I / F dedicated circuit 50 and drives the print head unit 60, and paper feeding. And a motor drive circuit 54 that drives the motor 22 and the carriage motor 24. The I / F dedicated circuit 50 receives the image data ID supplied from the computer 88 via the connector 56.

  The print head unit 60 includes a print head 28. The print head 28 includes a plurality of nozzle rows (described later) that eject ink, and an actuator circuit that operates a piezo element provided in each nozzle constituting each nozzle row. The actuator circuit is a part of the head drive circuit 52 and controls on / off of a drive signal supplied from a drive signal generation circuit (not shown) in the head drive circuit 52. That is, the actuator circuit latches dot data indicating on (ink is ejected) or off (ink is not ejected) for each nozzle in accordance with the print data supplied from the control circuit 40, and the drive signal is only for the nozzle that is on. Is applied to the piezo element.

  A print head unit 60 having the print head 28 is mounted on the carriage 30. Therefore, the print head 28 is reciprocally moved relative to the print medium along the sliding shaft 34 (along the main scanning direction) by the carriage motor 24 (FIG. 1). Further, the paper P is transported to the print head 28 by the paper feed motor 22 in the paper feed direction (sub-scanning direction).

  FIG. 3 is an explanatory diagram showing the arrangement of nozzles provided in the print head 28 of the inkjet printer 20 in the first embodiment. The inkjet printer 20 of the first embodiment performs printing using four colors of ink of black (K), cyan (C), magenta (M), and yellow (Y). Therefore, a plurality of nozzle rows corresponding to four ink colors are arranged in the print head 28 along the main scanning direction. Specifically, for each of the three chromatic color inks (cyan ink, yellow ink, and magenta ink), the print head 28 includes one nozzle row composed of 152 nozzles arranged in the sub-scanning direction. (Indicated as “C”, “Y”, and “M” in FIG. 3 respectively), the achromatic ink (black ink) is composed of 152 nozzles arranged in the sub-scanning direction. Four nozzle rows are arranged (indicated as “K0” to “K3” in FIG. 3).

  As shown in FIG. 3, the nozzle pitch of each nozzle row is the same. Regarding the positions along the sub-scanning direction, the positions of the cyan nozzle row, the magenta nozzle row, and the black nozzle row K0 are the same, and the positions of the yellow nozzle row and the black nozzle row K1 are the black nozzle row. This is a position shifted from the position of K0 by half the nozzle pitch. Further, the position of the black nozzle row K2 is a position shifted from the position of the black nozzle row K0 by a quarter of the nozzle pitch, and the position of the black nozzle row K3 is different from the position of the black nozzle row K1. This is a position shifted by a quarter of the nozzle pitch. Accordingly, the four black nozzle rows are arranged in the order of K0, K2, K1, and K3 while being shifted along the sub-scanning direction by a quarter of the nozzle pitch.

  Since the four black nozzle rows each have 152 nozzles, it can also be regarded as one nozzle row composed of a total of 608 nozzles. In this way, if the number of nozzles constituting each nozzle row for chromatic colors is K, the number of nozzles constituting the nozzle row for black is (n · K) (where n = 4). That is, the number of nozzles constituting the black nozzle row is four times the number of nozzles constituting each chromatic color nozzle row. The nozzle pitch of the black nozzle row is four times finer than the nozzle pitch of each chromatic color nozzle row.

  In this embodiment, the (n · K) nozzles constituting the black nozzle row are grouped into n / m black nozzle subgroups. Here, as will be described later, m is the number of image forming operations for unit band formation in the color area, and the value of m is 2 in the first embodiment. Therefore, as shown by a broken line in FIG. 3, the nozzles constituting the black nozzle row are grouped into 2 (= 4/2) black nozzle subgroups Kg0 and Kg1.

  One black nozzle subgroup Kg0 is constituted by two black nozzle rows K0 and K1, and the other black nozzle subgroup Kg1 is constituted by two black nozzle rows K2 and K3. As indicated by parenthesized nozzle numbers in FIG. 3, the black nozzle subgroups Kg0 and Kg1 can each be regarded as one nozzle row composed of a total of 304 nozzles in a so-called staggered arrangement. In this way, the number of nozzles constituting the black nozzle subgroup is (m · K) (where m = 2). That is, the number of nozzles constituting the black nozzle subgroup is twice the number of nozzles constituting each chromatic color nozzle row. Further, the nozzle pitches of the black nozzle subgroups are the same, and are twice as fine as the nozzle pitches of the chromatic color nozzle rows.

  Thus, the four nozzle rows for black can be regarded as one nozzle row in a staggered arrangement. Similarly, each black nozzle subgroup can also be regarded as one nozzle row in a staggered arrangement. In the example of FIG. 3, in each chromatic color nozzle row of the print head 28, the positions along the main scanning direction of the nozzles constituting the nozzle row are all the same (that is, the linear arrangement and However, each chromatic color nozzle row may be a so-called staggered nozzle row. That is, in this specification, “nozzle row” means a plurality of nozzles arranged side by side along the sub-scanning direction, and “a plurality of nozzles are arranged side by side along the sub-scanning direction”. Means that the positions of the plurality of nozzles along the sub-scanning direction are arranged so as to be different from each other regardless of the positions of the nozzles along the main scanning direction.

  Parameters that may differ for each color, such as the number of nozzles in each nozzle row and the nozzle pitch, are recorded in the internal memory 43 and are referred to by the printer driver 45.

A-2. Printing process:
FIG. 4 is a flowchart showing a flow of printing processing by the inkjet printer 20. The printing process is a process of forming an image on the paper P by converting the image data ID acquired from the computer 88 into print data and repeating the image forming operation and the conveying operation based on the print data. The printer driver 45 of the inkjet printer 20 controls each part of the inkjet printer 20 and executes a printing process.

  In the print processing, resolution conversion processing (step S110), ink color separation processing (step S120), halftone processing (step S130), rasterization processing (step S140), and recording processing (step S150) are executed. Is done. The resolution conversion process is a process for converting the resolution of the image data ID (for example, RGB data) so as to match the print resolution. The ink color separation process is a process of converting the image data ID after resolution conversion into ink amount data (for example, CMYK data) of each ink color of the inkjet printer 20. In the halftone process, the ink amount data obtained by the ink color separation process is binarized (or multivalued), and dots indicating ON / OFF of each color ink dot (or ink dot size) in each pixel This is processing for generating arrangement data. The rasterizing process is a process of rearranging the dot arrangement data in the order of the image forming operation in accordance with the nozzle arrangement of the inkjet printer 20, the transport amount of the paper P, and the like. The rasterization process generates print data that specifies the ink ejection mode (ink ejection / non-ejection or ejection ink amount) by each nozzle in each image forming operation. The print data includes command data for instructing each unit of the inkjet printer 20 to execute a specific operation.

  In the recording process, an image forming operation for ejecting ink to the print head unit 60 while reciprocating the carriage 30 on which the print head unit 60 is mounted is performed based on the print data, and the paper P is transported to the transport mechanism. This is a process of forming an image on the paper P by repeating the transport operation.

  FIG. 5 is an explanatory diagram illustrating an example of a recording method in the printing process performed by the inkjet printer 20 according to the first embodiment. FIG. 5 shows image regions when a print image is divided into a color region that is an image region that includes a chromatic color and a monochrome region that is an image region that does not include a chromatic color along the sub-scanning direction (paper feed direction). The position along the sub-scanning direction of the nozzle row used in each pass for forming the. In FIG. 5, the nozzle row is expressed as moving in the sub-scanning direction, but in actuality, the nozzle row is relative to the paper P by transporting the paper P in the sub-scanning direction. (The same applies to other figures).

  Here, “pass” means an operation of moving the print head 28 (FIG. 3) including each nozzle row in the forward or backward direction of the main scanning direction by the above-described moving mechanism. In FIG. 5, the path with the number “r” attached to the number of passes is a path for moving the print head 28 in the backward direction, and the other paths are paths for moving the print head 28 in the forward direction. The forward direction is a direction from a home position preset in the vicinity of one end of the movement path of the carriage 30 to the vicinity of the other end, and the backward direction is a direction opposite to the forward direction. Further, in each pass, when the “K” code is attached, the black nozzle row is used at the position along the sub-scanning direction of the rectangle attached with the “K” code, and the “Co” code is attached. In this case, each chromatic color nozzle row is used at a position along the sub-scanning direction of a rectangle with a “Co” symbol. In each pass, the black nozzle row is not used when the “K” code is not attached, and the chromatic color nozzle rows are not used when the “Co” code is not attached. Note that the black nozzle row or chromatic color nozzle row is used in each pass if the dot data corresponding to the pass contains data that should eject black ink or chromatic color ink. This means that the corresponding color ink is ejected from the nozzle row. Even when a black nozzle row or a chromatic color nozzle row is used in a certain pass, if there is no data to eject black ink or chromatic color ink in the dot data corresponding to that pass The corresponding color ink is not ejected from the corresponding nozzle row. Further, the pass involving the use of the black nozzle row or the chromatic color nozzle row corresponds to the above-described image forming operation. As will be described later, the pass may be a pass (empty pass) that does not involve the use of both the black nozzle row and the chromatic color nozzle row.

  In the example of FIG. 5, the print image is configured in the order of a color area, a monochrome area, a color area, a monochrome area,. Therefore, in the printing process, first, an image of a color area is formed. In the first color area, the first pass in the forward direction in which both the black nozzle row and the chromatic color nozzle row are used, and the second pass in the backward direction in which only the chromatic color nozzle row is used, An image having a predetermined width along the scanning direction (hereinafter also referred to as “unit band”) is formed. In the example of FIG. 5, the width of the unit band is a width corresponding to the length of each nozzle row. In the following, a path in which both the black nozzle row and the chromatic nozzle row are used is also referred to as a “black / chromatic color combined pass”, and a pass in which only the chromatic nozzle row is used is referred to as “chromatic color only”. Also referred to as “pass”, a pass in which only the black nozzle row is used is also referred to as “black only pass”. Subsequently, adjacent to the unit band formed by the first pass and the second pass by the third pass, which is a black / chromatic color combination pass in the forward direction, and the fourth pass, which is a pass only in the chromatic color in the backward direction. The next unit band is formed. As described above, in the color area, the forward and backward passes are alternately repeated, and one black / chromatic color combined pass in a specific direction (for example, the forward direction) and the reverse direction of the specific direction (for example, the backward direction). The recording method in which a unit band is formed by a total of two passes (image forming operation), ie, a single chromatic color pass). In other words, in the color area, the directions of the passes in which the black nozzle rows are used are all the same direction (specific direction). As will be described later, a transport operation (paper feed) for one main scanning line is performed between two passes forming a unit band.

  Further, as shown in FIG. 5 as the fifth pass and the sixth pass, in this embodiment, in addition to the case where the entire unit band to be formed is located in the color region, a part of the unit band to be formed is a color. The recording method in the color area described above is also used when the remaining part is located in the monochrome area. In this case, among the nozzles constituting the chromatic color nozzle row, the nozzles located in the monochrome area are masked and not used. When the entire unit band to be formed is located in the monochrome area, the following recording method in the monochrome area is adopted.

  In the first monochrome region in the example of FIG. 5, first, a unit band is formed by the seventh pass, which is a forward only black pass. Next, the next unit band adjacent to the unit band formed by the seventh pass is formed by the eighth pass, which is the black-only pass in the backward direction. In this way, in the monochrome area, a recording method is adopted in which only forward and backward black passes are alternately repeated, and unit bands are formed by a single black pass (image forming operation). In the subsequent ninth pass and tenth pass, a part of the unit band to be formed is located in the color area, and printing is performed according to the recording method in the color area described above.

  FIG. 6 is an explanatory diagram showing another example of the recording method in the printing process by the ink jet printer 20 of the first embodiment. In the example of FIG. 6, the recording method from the first pass to the seventh pass is the same as the example of FIG. In the example of FIG. 6, when the forward seventh pass is completed, a part of the unit band to be formed in the next backward eighth pass is located in the color area. Therefore, according to the recording method in the color area described above, the next eighth pass in the backward direction is a black / chromatic color combined pass. However, in this embodiment, the unit band immediately before the boundary with the color area in the monochrome area is the path in the same direction as the specific direction (the direction of the black / chromatic color combined path) described above when forming the other color areas. In this case, the next pass of the pass for forming the immediately preceding unit band is in a direction opposite to the specific direction without using any of the black nozzle row and the chromatic color nozzle row. It is assumed that the color area is formed by the empty pass and the subsequent passes. In the example of FIG. 6, the unit band immediately before the boundary with the color area in the monochrome area is formed by the seventh path that is the same direction as the specific direction (that is, the forward direction) in the first color area. The eighth pass, which is a path of the second, is an empty path in the reverse direction (reverse direction) to the specific direction (that is, a path that moves to the home position HP), and the subsequent ninth pass is a combination of black and chromatic colors in the same direction as the specific direction. It is a pass. In this way, the direction of the black / chromatic color combination pass is unified in the same direction in all color regions in the printed image.

  7 and 8 are explanatory diagrams illustrating an example of a recording method in the printing process by the ink jet printer 20 according to the first embodiment. 7 and 8 show positions along the sub-scanning direction of the nozzle rows used in each pass for forming each image area (color area and monochrome area) of the print image. 7 and 8, the positions of the nozzles constituting each nozzle row are indicated by numerals. Since the positions of the cyan nozzle row (C) and the magenta nozzle row (M) in the sub-scanning direction are the same, only the positions of either the cyan nozzle row or the magenta nozzle row are shown in FIGS. Is shown. In addition, nozzles marked with an X mark superimposed on the numbers indicating the nozzle positions represent nozzles that are not used in the pass.

  In the example of FIGS. 7 and 8, the chromatic color nozzle row is composed of seven nozzles for the sake of simplicity. As for black, each of the four black nozzle rows K0 to K3 is composed of 7 nozzles, forming one black nozzle row composed of a total of 28 nozzles. That is, if the number of nozzles constituting each nozzle row for chromatic color is K, the number of nozzles constituting the nozzle row for black is (n · K) (where n = 4). In the example of FIGS. 7 and 8, in the printed image, the area from the first main scanning line (first raster) to the 34th main scanning line is a color area, and from the 35th main scanning line to the 86th main scanning line. The area up to the line is a monochrome area, and the area after the 87th main scan line is a color area.

  As shown in FIG. 7, in the first color area, the forward black / chromatic color combined pass is executed as the first pass, and after the minute transport operation Sc for two main scanning lines is performed, Only the chromatic color in the backward direction is executed. The formation of the first unit band is completed by a total of two passes, the first pass and the second pass. Next, the main transport operation Sm for 26 main scan lines is performed, the forward black / chromatic color combined pass is executed as the third pass, and the micro transport operation Sc for 2 main scan lines is performed. Only the chromatic color in the backward direction is executed as the fourth pass. The formation of the next unit band is completed by a total of two passes, the third pass and the fourth pass. Since part of the unit band formed at this time is located in the monochrome area, the chromatic nozzles located in the monochrome area are masked and not used in each pass.

  As described above, in the color area, the forward and backward passes are alternately repeated, and one black / chromatic color combined pass in a specific direction (for example, the forward direction) and the reverse direction of the specific direction (for example, the backward direction). The recording method in which a unit band is formed by a total of two passes (image forming operation) including a single chromatic color pass). That is, in the color region, the chromatic color nozzle row is used in all image forming operations, and the black color nozzle row is used in only one image forming operation. Further, the directions of the passes in which the black nozzle rows are used are all the same direction (specific direction). The resolution along the sub-scanning direction of the main scanning line formed by the black nozzle row is twice as fine as the resolution along the sub-scanning direction of the main scanning line formed by the chromatic color nozzle row.

  In the first monochrome area, only the forward black pass is executed as the fifth pass (FIG. 8). With this one pass, the formation of the first unit band in the monochrome area is completed. In the example of FIG. 8, when the main transport operation Sm for 26 main scanning lines is performed after the fifth pass, a part of the unit band to be formed in the next pass is located in the color area. Therefore, in the example of FIG. 8, the unit band immediately before the boundary with the color area in the monochrome area is in the same direction as the specific direction (the direction of the combined black and chromatic color path) described above when forming the other color areas. It is formed by the pass. Accordingly, the sixth pass, which is the next pass, is a backward empty pass that does not involve the use of any nozzle row. Thereafter, after the main transport operation Sm for 26 main scan lines is performed, the second color area is formed by the seventh pass and thereafter. In the example of FIG. 8, the main transport operation Sm is performed after the sixth pass, which is an empty pass. However, the main transport operation Sm is performed after the fifth pass, and then the sixth pass, which is an empty pass. May be executed.

  As described above, in the recording process by the inkjet printer 20 of the first embodiment, the resolution (printing resolution) along the sub-scanning direction of the main scanning line formed by the black nozzle row in the color region is for chromatic colors. The resolution becomes 2 (= n / m) times finer than the resolution along the sub-scanning direction of the main scanning line formed by the nozzle rows. This is because the ratio n of the number of nozzles constituting the black nozzle row to the number of nozzles constituting each chromatic color nozzle row is 4, and the number m of image forming operations for unit band formation in the color region is m. This is because the value of is 2.

  In this embodiment, the (n · K) nozzles constituting the black nozzle row are grouped into 2 (= n / m) black nozzle subgroups Kg0 and Kg1 (FIG. 3). ). If each of the black nozzle subgroups Kg0 and Kg1 is a nozzle row of virtually different colors (for example, black A and black B), black A (with respect to the number of nozzles constituting each nozzle row for chromatic color Alternatively, the value of the ratio n of the number of nozzles constituting the black B) nozzle subgroup is 2. Therefore, the resolution along the sub-scanning direction of the main scanning line formed by the black A (or black B) nozzle sub-group is the resolution along the sub-scanning direction of the main scanning line formed by the chromatic color nozzle row. 1 (= n / m) times, that is, the same resolution. Thus, in this embodiment, the print resolution along the first direction of one image forming operation of each black nozzle subgroup is the first direction of m image forming operations of each chromatic color nozzle row. The (n · K) nozzles constituting the black nozzle row are grouped into a plurality of black nozzle sub-groups so as to be the same as the print resolution along the black line.

  FIG. 9 is an explanatory diagram showing an example of a recording method in consideration of grouping of the black nozzle rows. FIG. 9 shows a black nozzle subgroup Kg0 (black nozzle rows K0 and K1) and a black nozzle subgroup Kg1 (black nozzle rows K2 and K3) in the recording method shown in FIG. The figure which considered grouping with these is shown. As shown in FIG. 9, the resolution along the sub-scanning direction of the main scanning line formed by each black nozzle sub-group is the resolution along the sub-scanning direction of the main scanning line formed by the chromatic color nozzle row. Is the same as

  The print data generation unit 47 performs rasterization processing (step S140 in FIG. 4) assuming that the black nozzle subgroups Kg0 and Kg1 are nozzle rows of virtually different colors (black A and black B). Assuming that the black nozzle subgroups Kg0 and Kg1 are virtually different nozzle rows, printing is performed along the first direction in the image forming operation for each black nozzle subgroup and each chromatic color nozzle row. Since the resolution is the same, the rasterization process can be executed by a common method. The print data generation unit 47 performs rasterization processing on each black nozzle subgroup and each chromatic color nozzle row by a common method, and generates print data for each nozzle row. Note that the print data generation unit 47 converts the print data for each black nozzle subgroup to a position shift amount along the sub-scanning direction of each black nozzle subgroup (fourths of the nozzle pitch of the chromatic color nozzle row). 1) Print data for the nozzle array for black is generated by rearranging by shifting by 1).

  As described above, in the inkjet printer 20 of the present embodiment, assuming that the number of nozzles constituting each chromatic color nozzle row is K, the number of nozzles constituting the black nozzle row is (n · K) ( However, n = 4). In the printing process by the inkjet printer 20 of the present embodiment, in the color region, the forward direction and the backward direction pass are alternately repeated, and one black / chromatic color combined pass in the specific direction (for example, the forward direction) and the specific direction are performed. A recording method in which a unit band is formed by a total of two passes (image forming operation) including only one chromatic color pass in the reverse direction (for example, the backward direction) is used. That is, in each color region, the pass directions in which the black nozzle rows are used are all the same direction (specific direction). In a certain color area, when the direction of the pass in which the black nozzle row is used includes both the forward direction and the backward direction, the main scanning of the ruled line formed substantially parallel to the sub-scanning direction formed using black ink There is a possibility that a positional deviation along the direction (so-called Bi-d deviation) may occur. In the present embodiment, in all color areas, the directions of the paths in which the black nozzle rows are used are all unified in the same direction, so the occurrence of the ruled line misalignment can be suppressed, and the print image quality can be improved. be able to. In this embodiment, the number of nozzles constituting the black nozzle row is set to four times the number of nozzles constituting each chromatic color nozzle row, and the unit band in the color region is a single black / chromatic color combined pass. Since only one chromatic color is formed with a pass, it is possible to suppress a decrease in printing speed while suppressing the occurrence of the ruled line position deviation described above. Further, in the present embodiment, in the monochrome area, a recording method is adopted in which passes only in the forward and backward blacks are alternately repeated and a unit band is formed by a single black pass. The printing speed can be improved. In addition, since the chromatic ink is not ejected in the monochrome area, the amount of ink per unit area of the print medium is relatively small compared to the color area, and the deflection of the print medium is small. Therefore, in the monochrome area, even if only the forward and backward black paths are used together, there is little risk of occurrence of the ruled line position deviation described above. From the above, in the inkjet printer 20 of the present embodiment, it is possible to improve the print image quality while suppressing an increase in the time required for the printing process.

  In the inkjet printer 20 of the present embodiment, the unit band immediately before the boundary with the color area in the monochrome area is the same as the specific direction (direction of the black / chromatic color combined pass) described above when forming the other color areas. When formed by a direction pass, the pass next to the pass for forming the immediately preceding unit band is an empty pass that does not involve the use of either the black nozzle row or the chromatic color nozzle row. The color area is formed by the next pass and after. For this reason, in this embodiment, the direction of the black / chromatic color combined pass is unified in the same direction in all the color regions in the printed image. Here, in the forward black / chromatic color combination pass and the backward black / chromatic color combination pass, the overlapping order of the black ink dots and the chromatic ink dots on the printing medium is reversed. Therefore, if the image area formed by the forward black / chromatic color combination pass and the image area formed by the backward black / chromatic color combination pass are mixed in the printed image, color unevenness may occur. is there. In this embodiment, the direction of the black and chromatic color combined pass is unified in the same direction in all the color areas in the printed image, so that the occurrence of color unevenness can be suppressed and the print image quality can be further improved. it can.

  Further, in the inkjet printer 20 of the present embodiment, when the print data generation unit 47 generates the print data for the color area, it follows the sub-scanning direction in one image forming operation of each black nozzle sub-group. The (n · K) nozzles constituting the black nozzle row are made up of a plurality of black so that the print resolution is the same as the print resolution along the sub-scanning direction in m image forming operations of each chromatic color nozzle row. The chromatic color nozzle row print data and the black nozzle sub group print data are generated by a common method. Therefore, the print data generating unit 47 can execute rasterization processing for each black nozzle subgroup and each chromatic color nozzle row in a common manner, speeding up the printing processing, and reducing the required memory capacity. Can be realized.

B. Second embodiment:
FIG. 10 is an explanatory diagram showing the arrangement of nozzles provided in the print head 28a of the inkjet printer 20 in the second embodiment. The nozzle arrangement of the print head 28a in the second embodiment is that two nozzle rows each consisting of 152 nozzles are arranged for black ink. The print head 28 in the first embodiment shown in FIG. This is different from the nozzle arrangement. That is, the nozzle arrangement of the print head 28a in the second embodiment is an arrangement in which the black nozzle arrays K2 and K3 are excluded from the nozzle arrangement of the print head 28 in the first embodiment.

  The two black nozzle rows K0 and K1 arranged in the print head 28a can be regarded as one nozzle row composed of 304 nozzles, as indicated by parenthesized nozzle numbers in FIG. . In this way, assuming that the number of nozzles constituting each nozzle row for chromatic colors is K, the number of nozzles constituting the nozzle row for black is (n · K) (where n = 2). That is, the number of nozzles constituting the black nozzle row is twice the number of nozzles constituting each chromatic color nozzle row. The nozzle pitch of the black nozzle row is twice as fine as the nozzle pitch of each chromatic color nozzle row.

  In this embodiment, the (n · K) nozzles constituting the black nozzle row are grouped into n / m black nozzle subgroups. Here, as will be described later, m is the number of image forming operations for unit band formation in the color region, and the value of m is 1 in the second embodiment. Accordingly, the nozzles constituting the black nozzle row are grouped into 2 (= 2/1) black nozzle subgroups. One black nozzle subgroup corresponds to the black nozzle row K0, and the other black nozzle subgroup corresponds to the black nozzle row K1. The number of nozzles constituting each black nozzle subgroup is (m · K) (where m = 1). That is, the number of nozzles constituting the black nozzle subgroup is the same as the number of nozzles constituting each chromatic color nozzle row. The nozzle pitches of the black nozzle subgroups are the same as each other, and are the same as the nozzle pitches of the chromatic color nozzle rows.

  FIG. 11 is an explanatory diagram illustrating an example of a recording method in print processing by the inkjet printer 20 according to the second embodiment. FIG. 11 shows the positions along the sub-scanning direction of the nozzle rows used in each pass for forming each image area (color area and monochrome area) of the print image. In FIG. 11, the position of each nozzle constituting each nozzle row is indicated by a numeral. Since the positions of the cyan nozzle row (C) and the magenta nozzle row (M) along the sub-scanning direction are the same, FIG. 11 shows the position of only one of the cyan nozzle row and the magenta nozzle row. ing. In addition, nozzles marked with an X mark superimposed on the numbers indicating the nozzle positions represent nozzles that are not used in the pass.

  In the example of FIG. 11, for ease of explanation, each chromatic color nozzle row is composed of seven nozzles. As for black, each of the two black nozzle rows K0 and K1 is composed of 7 nozzles to form one black nozzle row composed of a total of 14 nozzles. That is, if the number of nozzles constituting each nozzle row for chromatic color is K, the number of nozzles constituting the nozzle row for black is (n · K) (where n = 2). In the example of FIG. 11, in the printed image, the area from the first main scanning line (first raster) to the 39th main scanning line is a color area, and the area after the 40th main scanning line is a monochrome area. .

  As shown in FIG. 11, in the first color region, the forward black / chromatic color combined pass is executed as the first pass, and the formation of the first unit band is completed by the first pass. That is, in this embodiment, only the chromatic color pass is not executed, and the value of the number m of image forming operations for unit band formation in the color region is 1. In the unit band formed at this time, the resolution along the sub-scanning direction of the main scanning line formed by the black nozzle row (black nozzle row K0 and black nozzle row K1) is the chromatic color nozzle row. The resolution is twice as fine as the resolution along the sub-scanning direction of the main scanning line formed by the above.

  Subsequently, after the main transport operation Sm for 14 main scanning lines is performed, the forward black / chromatic color combined pass is executed as the second pass, and the formation of the next unit band is completed by the second pass. . Further, after the main transport operation Sm for 14 main scanning lines is performed, the forward black / chromatic color combined pass is executed as the third pass, and the formation of the next unit band is completed by the third pass. . Note that since a part of the unit band formed at this time is located in the monochrome area, the chromatic color nozzles located in the monochrome area are masked and not used.

  As described above, in the color area, only the forward pass is repeatedly executed, and a recording method is employed in which a unit band is formed by one black / chromatic color combined pass (image forming operation) in the forward direction. That is, in the color region, all the directions of the passes in which the black nozzle rows are used are the same direction.

  In the first monochrome area, only the forward black pass is executed as the fourth pass. With the fourth pass, the formation of the first unit band in the monochrome area is completed. Subsequently, after the main transport operation Sm for 14 main scanning lines is performed, only the forward black pass is executed as the fifth pass, and the formation of the next unit band is completed by the fifth pass.

  As described above, in the recording process performed by the ink jet printer 20 of the second embodiment, in the color region, the resolution along the sub-scanning direction of the main scanning line formed by the black nozzle row is formed by the chromatic color nozzle row. The resolution is 2 (= n / m) times finer than the resolution along the sub-scanning direction of the main scanning line. This is because the ratio n of the number of nozzles constituting the black nozzle row to the number of nozzles constituting each chromatic color nozzle row is 2, and the number m of image forming operations for unit band formation in the color region is m. This is because the value of is 1.

  Here, in the second embodiment, the (n · K) nozzles constituting the black nozzle row are composed of 2 (= n / m) black nozzle subgroups (black nozzle row K0 and black nozzle). Grouped into a column K1) (FIG. 10). Assuming that the two black nozzle subgroups are nozzle rows of virtually different colors (for example, black A and black B), black A (or black B) with respect to the number of nozzles constituting each chromatic color nozzle row The value of the ratio n of the number of nozzles constituting the nozzle sub-group is 1. Therefore, the resolution along the sub-scanning direction of the main scanning line formed by the black A (or black B) nozzle sub-group is the resolution along the sub-scanning direction of the main scanning line formed by the chromatic color nozzle row. 1 (= n / m) times, that is, the same resolution. Thus, in this embodiment, the print resolution along the first direction in one image forming operation of each black nozzle subgroup is the first direction in m image forming operations of each chromatic color nozzle row. The (n · K) nozzles constituting the black nozzle row are grouped into a plurality of black nozzle sub-groups so as to be the same as the print resolution along the black line.

  Also in the second embodiment, as in the first embodiment, the print data generation unit 47 assigns two black nozzle subgroups (black nozzle row K0 and black nozzle row K1) to virtually different colors ( Rasterizing processing (step S140 in FIG. 4) is performed assuming that the nozzle rows are black A and black B). Assuming that each black nozzle subgroup is a nozzle row of virtually different colors, the print resolution along the first direction in the image forming operation is the same for each black nozzle subgroup and each chromatic color nozzle row. Since they are the same, the rasterization process can be executed in a common way. The print data generation unit 47 performs rasterization processing on each black nozzle subgroup and each chromatic color nozzle row by a common method, and generates print data for each nozzle row. The print data generation unit 47 converts the print data for each black nozzle subgroup to the amount of misalignment along the sub-scanning direction of each black nozzle subgroup (two times the nozzle pitch of the chromatic color nozzle row). 1) Print data for the nozzle array for black is generated by rearranging by shifting by 1).

  As described above, in the inkjet printer 20 of the second embodiment, assuming that the number of nozzles constituting each chromatic color nozzle row is K, the number of nozzles constituting the black nozzle row is (n · K). (Where n = 2). In the printing process by the inkjet printer 20 of the present embodiment, a recording method in which unit bands are formed in the color region by one black / chromatic color combined pass (image forming operation) in the forward direction is employed. That is, in each color region, the pass directions in which the black nozzle rows are used are all the same direction. For this reason, occurrence of ruled line misalignment can be suppressed, and the print image quality can be improved.

  In the inkjet printer 20 of the second embodiment, when the print data generation unit 47 generates the print data for the color area, it follows the sub-scanning direction in one image forming operation of each black nozzle subgroup. The (n · K) nozzles constituting the black nozzle row are arranged so that the print resolution is the same as the print resolution along the sub-scanning direction in the m image forming operations of each chromatic color nozzle row. The black nozzle subgroups are grouped, and the print data for the chromatic color nozzle rows and the print data for each black nozzle subgroup are generated by a common method. Therefore, the print data generating unit 47 can execute rasterization processing for each black nozzle subgroup and each chromatic color nozzle row in a common manner, speeding up the printing processing, and reducing the required memory capacity. Can be realized.

C. Third embodiment:
FIG. 12 is an explanatory diagram illustrating an example of a recording method in print processing by the inkjet printer 20 according to the third embodiment. The configuration of the print head 28 of the ink jet printer 20 of the third embodiment is the same as that of the first embodiment shown in FIG. That is, in the print head 28, each chromatic color nozzle row composed of 152 nozzles and four black nozzle rows each composed of 152 nozzles are arranged. If the number of nozzles constituting each nozzle row for chromatic color is K, the number of nozzles constituting the nozzle row for black is (n · K) (where n = 4). The (n · K) nozzles constituting the black nozzle row are grouped into n / m black nozzle subgroups. As will be described later, m is the number of image forming operations for forming a unit band in the color area, and the value of m is 2 in the third embodiment. Accordingly, the nozzles constituting the black nozzle row are grouped into 2 (= 4/2) black nozzle subgroups Kg0 and Kg1. One black nozzle subgroup Kg0 is constituted by two black nozzle rows K0 and K1, and the other black nozzle subgroup Kg1 is constituted by two black nozzle rows K2 and K3.

  FIG. 12 shows image regions when a print image is divided into a color region that is an image region that includes a chromatic color and a monochrome region that is an image region that does not include a chromatic color along the sub-scanning direction (paper feeding direction). The position along the sub-scanning direction of the nozzle row used in each pass for forming the.

  As shown in FIG. 12, in the third embodiment, in the same manner as in the first embodiment shown in FIG. 5, the forward and backward passes are alternately repeated in the color area, and a specific direction (eg, forward direction). A unit of a total of two passes (m = 2) (image forming operation) of one black / chromatic color combination pass and one chromatic color pass in the reverse direction (for example, backward direction) in a specific direction. A recording method that completes the formation of the band is adopted. In other words, in the color area, the directions of the passes in which the black nozzle rows are used are all the same direction (specific direction).

  However, in the third embodiment, the width of the unit band formed by a total of two passes is smaller than the length of the nozzle row. In the third embodiment, the transport operation is executed with a feed amount such that the positions of the nozzle rows along the sub-scanning direction in the two passes that are executed one after the other in the same pass direction overlap. . For example, as shown in FIG. 12, the positions of the nozzle rows along the sub-scanning direction in the first pass and the third pass, which are forward passes executed in succession, partially overlap, The positions of the nozzle rows along the sub-scanning direction in the second pass and the fourth pass also partially overlap. When printing is performed in such a manner, there are a plurality of passes in which main scanning lines can be formed for at least some of the main scanning lines (raster). In the present embodiment, each main scanning line is formed in one pass, so that a main scanning line that can be formed in a plurality of passes is formed in one selected pass among the plurality of passes. Nozzles that are not involved in the formation of the main scan line in each pass are masked and not used.

  In the monochrome area, a recording method is adopted in which passes only in the forward and backward black are alternately repeated and a unit band is formed by a single black pass (image forming operation).

  FIG. 13 is an explanatory diagram illustrating an example of a recording method in print processing by the ink jet printer 20 according to the third embodiment. FIG. 13 shows positions along the sub-scanning direction of the nozzle rows used in each pass for forming the color area of the print image. In FIG. 13, the position of each nozzle constituting each nozzle row is indicated by a numeral. Since the positions of the cyan nozzle row (C) and the magenta nozzle row (M) in the sub-scanning direction are the same, only one position of the cyan nozzle row and the magenta nozzle row is shown. Further, the positions of the black nozzle rows are grouped into black nozzle subgroups Kg0 (black nozzle rows K0 and K1) and black nozzle subgroups Kg1 (black nozzle rows K2 and K3). . In addition, nozzles marked with an X mark superimposed on the numbers indicating the nozzle positions represent nozzles that are not used in the pass.

  In the example of FIG. 13, for ease of explanation, each chromatic color nozzle row is composed of eight nozzles. The black nozzle row constitutes 16 nozzles constituting the black nozzle subgroup Kg0 (black nozzle rows K0 and K1) and the black nozzle subgroup Kg1 (black nozzle rows K2 and K3). It is composed of a total of 32 nozzles, 16 nozzles. That is, if the number of nozzles constituting each nozzle row for chromatic color is K, the number of nozzles constituting the nozzle row for black is (n · K) (where n = 4).

  As shown in FIG. 13, in the first color area, the forward black / chromatic color combination pass is executed as the first pass, and after the transport operation Sk for six main scanning lines is performed, the second pass is restored. Only the chromatic color of the direction is executed. In the first pass (black / chromatic color combined pass), nozzles (first and second nozzles) located outside the range of the paper P in each nozzle row and nozzles located on the most upstream side in the sub-scanning direction ( The eighth nozzle) is not used. In the second pass (only the chromatic color pass), the nozzles (first nozzles for C and M) located outside the range of the paper P in each nozzle row are located upstream in the sub-scanning direction. Nozzles (seventh and eighth nozzles for C and M and sixth to eighth nozzles for Y) are not used. The formation of the first unit band composed of the first main scanning line to the twentieth main scanning line is completed by two passes in total, that is, the first pass and the second pass. In the unit band formed at this time, the resolution along the sub-scanning direction of the main scanning line formed by the black nozzle row is along the sub-scanning direction of the main scanning line formed by the chromatic color nozzle row. The resolution is twice as fine as the resolution.

  Next, the transport operation Sk for 14 main scan lines is performed, the forward black / chromatic color combined pass is executed as the third pass, and the transport operation Sk for 6 main scan lines is performed. Only a chromatic color in the backward direction is executed as a pass. In the third pass (black / chromatic color combined pass), the nozzles (first and second nozzles) located on the already formed main scanning line and the most upstream side along the sub-scanning direction in each nozzle row No nozzle (eighth nozzle) is used. In the fourth pass (only the chromatic color pass), the nozzles (first nozzles for C and M) located on the already formed main scanning line in each nozzle row and the upstream side in the sub-scanning direction. No nozzles (7th and 8th nozzles for C and M and 6th and 8th nozzles for Y) are not used. The formation of the next unit band constituted by the 21st main scanning line to the 40th main scanning line is completed by the third pass and the fourth pass in total.

  As described above, in the color area, the forward and backward passes are alternately repeated, and one black / chromatic color combined pass in a specific direction (for example, the forward direction) and the reverse direction of the specific direction (for example, the backward direction). The recording method in which a unit band is formed by a total of two passes (image forming operation) including a single chromatic color pass). That is, in the color region, the chromatic color nozzle row is used in all image forming operations, and the black nozzle row is used in only one image forming operation. Further, the directions of the passes in which the black nozzle rows are used are all the same direction (specific direction).

  As described above, in the recording process by the ink jet printer 20 of the third embodiment, in the color region, the resolution along the sub-scanning direction of the main scanning line formed by the black nozzle row is formed by the chromatic color nozzle row. The resolution is 2 (= n / m) times finer than the resolution along the sub-scanning direction of the main scanning line. This is because the ratio n of the number of nozzles constituting the black nozzle row to the number of nozzles constituting each chromatic color nozzle row is 4, and the number m of image forming operations for unit band formation in the color region is m. This is because the value of is 2.

  Here, in this embodiment, assuming that the black nozzle subgroups Kg0 and Kg1 are nozzle rows of virtually different colors (for example, black A and black B), the nozzles constituting each chromatic color nozzle row The ratio n of the number of nozzles constituting the nozzle subgroup for black A (or black B) with respect to the number is 2. Therefore, the resolution along the sub-scanning direction of the main scanning line formed by the black A (or black B) nozzle sub-group is the resolution along the sub-scanning direction of the main scanning line formed by the chromatic color nozzle row. 1 (= n / m) times, that is, the same resolution. Thus, in this embodiment, the print resolution along the first direction in one image forming operation of each black nozzle subgroup is the first direction in m image forming operations of each chromatic color nozzle row. The (n · K) nozzles constituting the black nozzle row are grouped into a plurality of black nozzle sub-groups so as to be the same as the print resolution along the black line.

  The print data generation unit 47 performs the rasterizing process (step S140 in FIG. 4) assuming that the black nozzle subgroups Kg0 and Kg1 are nozzle rows of virtually different colors (black A and black B). Assuming that each black nozzle subgroup is a nozzle row of virtually different colors, the print resolution along the first direction in the image forming operation is the same for each black nozzle subgroup and each chromatic color nozzle row. Since they are the same, the rasterization process can be executed in a common way. The print data generation unit 47 performs rasterization processing on each black nozzle subgroup and each chromatic color nozzle row by a common method, and generates print data for each nozzle row. The print data generation unit 47 converts the print data for each black nozzle subgroup to the amount of misalignment along the sub-scanning direction of each black nozzle subgroup (two times the nozzle pitch of the chromatic color nozzle row). 1) Print data for the nozzle array for black is generated by rearranging by shifting by 1).

  In the rasterization process, the print data generation unit 47 specifies the positions along the sub-scanning direction of each nozzle in each pass based on the nozzle arrangement and the transport operation amount in the print head 28, and determines the nozzle to be used in each pass. . In the third embodiment, as described above, there are a plurality of paths that can form the main scanning line for at least some of the main scanning lines. When the position of a nozzle for a certain color in one pass is the same as the nozzle position for that color in another pass, the print data generation unit 47 sets the nozzle to use any one of the nozzles. Set other nozzles not to use.

  For example, in the example of FIG. 13, the eighth nozzle of the black nozzle row K1 for the first pass and the third nozzle of the black nozzle row K1 for the third pass are both positioned on the 23rd main scan line (R23). Located in. In this case, for example, the black twenty-third main scanning line is formed by the third nozzle of the black nozzle row K1 in the third pass, and the eighth nozzle of the black nozzle row K1 is not used in the first pass. In addition, the eighth nozzle of the yellow nozzle row Y for the first pass and the third nozzle of the yellow nozzle row Y for the third pass are both positioned at the 23rd main scanning line (R23). In this case, the yellow 23rd main scanning line is formed by, for example, the third nozzle of the yellow nozzle row Y in the third pass, and the eighth nozzle of the yellow nozzle row Y is not used in the first pass. The seventh nozzle of the cyan nozzle row C for the second pass and the second nozzle of the cyan nozzle row C for the fourth pass are both positioned at the 23rd main scanning line (R23). In this case, the cyan 23rd main scan line is formed by, for example, the second nozzle of the cyan nozzle row C in the fourth pass, and the seventh nozzle of the cyan nozzle row C is not used in the second pass.

  In addition, the process which determines the nozzle used in each pass can be performed by the well-known method described in Unexamined-Japanese-Patent No. 2005-319616 or Unexamined-Japanese-Patent No. 2006-264056, for example.

  The print data generation unit 47 determines a nozzle to be used in each pass, creates a scheduling table, and generates print data for the chromatic color nozzle row and print data for the black nozzle row using the scheduling table. The scheduling table is stored in the internal memory 43.

  14 and 15 are explanatory diagrams illustrating an example of a scheduling table. FIG. 14 shows an example of the scheduling table Tk for the black nozzle subgroup, and FIG. 15 shows an example of the scheduling table Tc for the cyan nozzle row. As shown in FIGS. 14 and 15, the scheduling tables Tk and Tc are tables for recording the positions along the sub-scanning direction of each nozzle in each pass and the ink ejection mode (use / non-use) of each nozzle. . In the figure, among the nozzles constituting the nozzle row, the nozzles used in each pass are indicated by black circles, and the nozzles not used are indicated by white circles. Further, the position (main scanning number) along the sub-scanning direction of the nozzle in the pass is shown to the right of the nozzle (the nozzle indicated by a black circle) to be used. The black nozzle subgroup scheduling table Tk corresponds to the number of nozzles constituting one black nozzle subgroup (that is, 16 nozzles from the first nozzle to the 16th nozzle). Shared by the black nozzle subgroup.

  For example, as shown in FIG. 14, in the first pass, 10 nozzles from the 5th nozzle to the 14th nozzle among the 16 nozzles constituting each black nozzle subgroup are used, and the other nozzles are used. Is not used. Similarly, in the third pass, ten nozzles from the fifth nozzle to the fourteenth nozzle among the 16 nozzles constituting each black nozzle subgroup are used, and the other nozzles are not used.

  On the other hand, as shown in FIG. 15, in the first pass, five nozzles from the third nozzle to the seventh nozzle among the eight nozzles constituting the cyan nozzle row C are used, and the other nozzles are Not used. In the second pass, among the eight nozzles constituting the cyan nozzle row C, five nozzles from the second nozzle to the sixth nozzle are used, and the other nozzles are not used. A scheduling table is similarly created for chromatic colors other than cyan.

  Here, in this embodiment, the scheduling table is shared for black and chromatic colors. That is, a scheduling table corresponding to the number of nozzles (16) constituting one black nozzle subgroup is prepared, and only a necessary area in the table is used. For example, as shown in FIG. 15, in the scheduling table Tc for cyan, only the area corresponding to 8 nozzles is used in the scheduling table area, and the remaining area Px is not used. Therefore, in the third embodiment, the capacity of the internal memory 43 for storing the scheduling table can be reduced.

  In the third embodiment, in each color area, the pass directions in which the black nozzle rows are used are all the same direction, so that the occurrence of ruled line misalignment can be suppressed and the print image quality can be improved. Can do. In the second embodiment, the print data generation unit 47 groups (n · K) nozzles constituting the black nozzle row into 2 (= n / m) black nozzle subgroups. Therefore, the resolution along the sub-scanning direction of the main scanning line formed by each black nozzle subgroup is the same as the resolution along the sub-scanning direction of the main scanning line formed by the chromatic color nozzle row. Therefore, rasterization processing can be executed for each black nozzle subgroup and each chromatic color nozzle row in a common manner, and printing processing can be speeded up and a required memory capacity can be reduced.

D. Fourth embodiment:
FIG. 16 is an explanatory diagram illustrating an example of a recording method in print processing by the inkjet printer 20 according to the fourth embodiment. FIG. 16 shows the positions along the sub-scanning direction of the nozzle rows used in each pass for forming the color area at the lower end of the paper P in the printed image. In the example of FIG. 16, the 78th main scanning line indicated as the final raster corresponds to the lower end of the paper P.

  The configuration of the print head 28 of the inkjet printer 20 of the fourth embodiment is the same as that of the first embodiment shown in FIG. That is, in the print head 28, each chromatic color nozzle row composed of 152 nozzles and four black nozzle rows each composed of 152 nozzles are arranged. If the number of nozzles constituting each nozzle row for chromatic color is K, the number of nozzles constituting the nozzle row for black is (n · K) (where n = 4). The (n · K) nozzles constituting the black nozzle row are grouped into n / m black nozzle subgroups. As will be described later, m is the number of image forming operations for forming a unit band in the color area, and the value of m is 2 in the third embodiment. Accordingly, the nozzles constituting the black nozzle row are grouped into 2 (= 4/2) black nozzle subgroups Kg0 and Kg1. One black nozzle subgroup Kg0 is constituted by two black nozzle rows K0 and K1, and the other black nozzle subgroup Kg1 is constituted by two black nozzle rows K2 and K3.

  In the example of FIG. 16, for ease of explanation, each of the chromatic nozzle rows is composed of eight nozzles, and the black nozzle row is a black nozzle subgroup Kg0 (black nozzle rows K0 and K1). 16 nozzles and 16 nozzles constituting the black nozzle subgroup Kg1 (black nozzle rows K2 and K3), a total of 32 nozzles. That is, if the number of nozzles constituting each nozzle row for chromatic color is K, the number of nozzles constituting the nozzle row for black is (n · K) (where n = 4).

  In the color area, the forward and backward passes are alternately repeated, and one black / chromatic color combined pass in a specific direction (for example, the forward direction) and once in the reverse direction (for example, the backward direction) of the specific direction. A unit band is formed by a total of two passes (image forming operation) including only the chromatic color pass. That is, in the color region, the chromatic color nozzle row is used in all image forming operations, and the black nozzle row is used in only one image forming operation. Further, the directions of the passes in which the black nozzle rows are used are all the same direction (specific direction). In the unit band formed at this time, the resolution along the sub-scanning direction of the main scanning line formed by the black nozzle row is along the sub-scanning direction of the main scanning line formed by the chromatic color nozzle row. The resolution is twice as fine as the resolution.

  Here, in this embodiment, assuming that the black nozzle subgroups Kg0 and Kg1 are nozzle rows of virtually different colors (for example, black A and black B), the nozzles constituting each chromatic color nozzle row The ratio n of the number of nozzles constituting the nozzle subgroup for black A (or black B) with respect to the number is 2. Therefore, the resolution along the sub-scanning direction of the main scanning line formed by the black A (or black B) nozzle sub-group is the resolution along the sub-scanning direction of the main scanning line formed by the chromatic color nozzle row. 1 (= n / m) times, that is, the same resolution. The print data generation unit 47 performs rasterization processing (step S140 in FIG. 4) assuming that the black nozzle subgroups Kg0 and Kg1 are virtually different nozzle rows. In this way, since all the colors have the same resolution, the rasterizing process can be executed by a common method.

  At the lower end of the paper P, if printing in the form executed in the central portion of the paper P (hereinafter referred to as normal printing) is continuously performed, the main scanning line may not be continuously formed in the sub-scanning direction. . In such a case, in order to continuously form main scanning lines in the sub-scanning direction, printing in a mode different from normal printing (hereinafter referred to as lower end printing) is performed. In the lower end printing of the present embodiment, the carry amount is changed from the normal printing. The print data generation unit 47 performs rasterization processing so that lower end printing can be executed. Rasterization processing for bottom edge printing can be executed by a known method described in, for example, Japanese Patent Application Laid-Open No. 2006-264056. Specifically, the print data generation unit 47 creates a scheduling table (hereinafter referred to as a virtual scheduling table) when it is assumed that normal printing is continuously performed at the lower end instead of lower end printing, and lower end printing is performed. , A scheduling table for bottom-end printing is created so that ink is ejected in the main scanning line that is supposed to eject ink in the virtual scheduling table.

  In the example of FIG. 16, up to the 97th pass is executed as normal printing, and the subsequent passes are executed as bottom-end printing. At this time, the print data generation unit 47 uses the virtual scheduling table on the assumption that the virtual normal printing process after the 98th pass (hereinafter referred to as dummy process) is continuously executed, as in the normal printing. Create by the method of. That is, the positions of the nozzles that should eject ink in each pass are specified so that the main scanning line is continuously formed in the sub-scanning direction up to the final main scanning line. FIG. 16 shows the used nozzles and their positions specified in the 98th-100th pass of the dummy process.

  Next, the print data generation unit 47 specifies the position of each nozzle when the paper P is transported by a transport amount set in advance for bottom-end printing, and ejects ink using the virtual scheduling table. The nozzle used in the lower end printing is specified so that ink is ejected to the scanning line. For example, in the 78th main scanning line (final main scanning line), ink should be ejected by the fourth nozzle of the black nozzle subgroup Kg1 in the 99th pass in the forward direction of the dummy process. Therefore, the print data generation unit 47 sets that the ink should be ejected by the sixth nozzle of the black nozzle subgroup Kg1 located in the 78th main scanning line in the 99th pass in the forward direction of the bottom end printing. Similarly, for example, in the 63rd main scan line, ink should be ejected by the third nozzle of the yellow nozzle row Y in the 98th pass of the dummy process. Accordingly, the print data generation unit 47 sets that ink should be ejected by the second nozzle of the yellow nozzle row Y located in the 63rd main scan line in the 99th pass of the lower end printing.

  The print data generation unit 47 individually creates a virtual scheduling table for each color, creates a scheduling table for lower end printing using the virtual scheduling table, and prints data for chromatic nozzle rows and prints for black nozzle rows. Generate data. The virtual scheduling table is stored in the internal memory 43. 17 and 18 are explanatory diagrams illustrating an example of the virtual scheduling table. FIG. 17 shows an example of the virtual scheduling table DTk for the black nozzle subgroup, and FIG. 18 shows an example of the virtual scheduling table DTc for the cyan nozzle row. As shown in FIGS. 17 and 18, the virtual scheduling tables DTk and DTc are tables that specify nozzles to be used in each virtual pass. In the figure, among the nozzles constituting the nozzle row, nozzles used in each pass are indicated by black circles, and nozzles not used are indicated by white circles. Further, the position (main scanning line number) along the sub-scanning direction of the nozzle in the pass is shown to the right of the used nozzle (nozzle indicated by a black circle).

  The virtual scheduling table DTk for the black nozzle subgroup corresponds to the number of nozzles constituting one black nozzle subgroup (that is, 16 nozzles from the first nozzle to the 16th nozzle). Shared by the nozzle subgroup. For example, as shown in FIG. 17, in the 99th pass, 8 nozzles from the 5th nozzle to the 12th nozzle are used among the 16 nozzles constituting each black nozzle subgroup, and the other nozzles are used. Is not used.

  On the other hand, the cyan nozzle row virtual scheduling table DTc corresponds to the number of nozzles constituting the cyan nozzle row (that is, eight nozzles from the first nozzle to the eighth nozzle). As shown in FIG. 18, in the 98th pass, four nozzles from the second nozzle to the fifth nozzle among the eight nozzles constituting the cyan nozzle row C are used, and the other nozzles are not used. . In the 99th pass, four nozzles from the third nozzle to the sixth nozzle are used among the eight nozzles constituting the cyan nozzle row C, and the other nozzles are not used. Note that the virtual scheduling table DT for the cyan nozzle row is also used for other chromatic colors.

  As described above, in the fourth embodiment, the virtual scheduling table used for the lower end printing is separately prepared for black and chromatic colors. Therefore, lower end printing can be executed by using a virtual scheduling table prepared separately for both printing with a black nozzle row and printing with a chromatic color nozzle row having different resolutions in the sub-scanning direction.

  In the fourth embodiment, the pass directions in which the black nozzle rows are used are the same in each color region, so that the occurrence of ruled line misalignment can be suppressed and the print image quality can be improved. Can do.

E. Variations:
The present invention is not limited to the above-described examples and embodiments, and can be implemented in various modes without departing from the gist thereof. For example, the following modifications are possible.

E1. Modification 1:
In each of the above embodiments, if the number of nozzles constituting each chromatic color nozzle row is K and the number of nozzles constituting the black nozzle row is (n · K), the value of n is 2 or 4. However, the value of n may be any value other than 2 and 4 as long as it is an integer of 2 or more. Regardless of the value of n, in the color region, the forward and backward passes are alternately repeated, and one black / chromatic color combined pass in a specific direction and (m−1) forward and backward passes. A recording method in which a unit band is formed by a total of m passes (image forming operation) with only a chromatic color pass (m is an integer of 2 or more and n or less) is adopted, and only one black pass is passed in the monochrome area. A recording method in which a unit band is formed may be adopted.

  When the value of n is an even number, the combination of the direction of a series of passes for forming each unit band can be unified in each color region. For example, when the recording method in which the value of n is 4 and a unit band is formed by a total of four passes is adopted, the combination of the direction of a series of passes for forming each unit band is, for example, , Forward direction, backward direction, forward direction, and backward direction can be unified. On the other hand, for example, when a recording method in which the value of n is 3 and a unit band is formed by a total of three passes is adopted, the combination of the direction of a series of passes for forming each unit band is For example, the combination of the direction of a series of paths is a combination of the forward direction, the backward direction, and the forward direction for a certain unit band, and the combination of the backward direction, the forward direction, and the backward direction for the next unit band. It is difficult to unify. If the combination of the directions of a series of passes for forming each unit band is not unified, the processing becomes complicated, for example, adjustment of the transport amount in the transport operation is necessary to eliminate missing of the main scanning line (raster). There is a fear. Therefore, it is preferable that the value of n is an even number from the viewpoint of speeding up by simplification of processing.

  In each of the above embodiments, a recording method is adopted in which the pass is repeated alternately only in the forward and backward black directions in the monochrome area. However, in the monochrome area, only the black in the forward and backward directions is used. A recording method in which only the pass is repeated may be employed. In this way, it is possible to effectively suppress the occurrence of misalignment of the ruled lines in the monochrome area, although there is a risk of increasing the printing time.

  Further, the recording method in the color area and the monochrome area is not limited to the method of the above embodiment. For example, the formation of the unit band in the color region may be realized by a plurality of black / chromatic color combined passes, or the formation of the unit band in the monochrome region may be realized by a plurality of passes of black only.

E2. Modification 2:
In each of the above-described embodiments, the first specific direction pass among the multiple passes performed for forming the unit band in the color region is the black / chromatic color combined pass, but it is not always necessary to do so. . For example, in the example of FIG. 8, the second specific direction path, not the first path that is the first specific direction path among the first to fourth paths performed for forming the first unit band. The third pass may be a black / chromatic color combined pass. That is, as long as the direction of the black / chromatic color combination pass is unified in a certain color area, one of the multiple passes performed for forming the unit band is used as the black / chromatic color combined pass. The remaining paths may be chromatic colors only. However, since the amount of ink in the unit band region on the print medium increases each time the passes are overlapped and the deflection of the print medium tends to increase, among the multiple passes performed for forming the unit band, It is preferable from the viewpoint of suppressing the occurrence of ruled line deviation that the path executed earlier is a black / chromatic color combined path.

E3. Modification 3:
In each of the above embodiments, when the unit band immediately before the boundary with the color area in the monochrome area is formed by the path in the same direction as the specific direction described above when forming the other color area, for example, The pass after the pass for forming the unit band is an empty pass opposite to the specific direction that does not involve the use of either the black nozzle row or the chromatic color nozzle row. In this way, the direction of the black and chromatic color combined pass is unified in the same direction for all the color areas in the printed image, and the print quality is further improved by suppressing the occurrence of color unevenness. In such a case, for example, the empty pass is not executed, and the pass next to the pass for forming the unit band immediately before may be used as the pass for forming the color region. . Even in this case, if the individual color regions in the printed image are viewed, the directions of the paths in which the black nozzle rows are used are all the same direction (specific direction), and therefore the occurrence of ruled line deviation can be suppressed. .

E4. Modification 4:
The grouping method into the black nozzle subgroup in each of the above embodiments is merely an example, and the printing resolution along the first direction in one image forming operation of each black nozzle subgroup is the chromatic color nozzle. As long as the printing resolution is the same as the printing resolution along the first direction in the m times of image forming operations in the column, the grouping may be performed by another method. Even in this case, the rasterizing process can be executed in a common manner for each black nozzle subgroup and each chromatic color nozzle row, thereby realizing high-speed printing and a reduction in necessary memory capacity. be able to.

E5. Modification 5:
In the third embodiment, the black nozzle subgroup scheduling table Tk corresponds to the number of nozzles constituting one black nozzle subgroup, and is shared by the black nozzle subgroups. However, the scheduling table Tk may correspond to the number of nozzles constituting all the black nozzle rows. Even in this case, the capacity of the internal memory 43 for storing the scheduling table can be reduced.

  In the fourth embodiment, the virtual scheduling table DTk for the black nozzle subgroup is created. However, the virtual scheduling table corresponding to the number of nozzles constituting all the black nozzle rows is created. Also good.

E6. Modification 6:
The configuration of the inkjet printer 20 in each of the above embodiments is merely an example, and the configuration of the inkjet printer 20 can be variously modified. For example, in each of the embodiments described above, the inkjet printer 20 is a printer that performs printing using a total of four inks, black ink as an achromatic color and cyan, magenta, and yellow ink as chromatic colors. The inkjet printer 20 may be a printer that performs printing using four or less colors, or six or more colors, as long as both the achromatic color ink and the chromatic color ink are included. Regardless of the number of ink colors used, the print head 28 of the inkjet printer 20 is provided with a nozzle row corresponding to each ink color.

  In each of the above embodiments, the inkjet printer 20 receives the image data ID from the computer 88, and the printer driver 45 of the control circuit 40 generates print data from the image data ID. It is good also as what functions as a control part to control. In this case, the computer 88 functions as a printer driver, generates print data from the image data ID, and supplies the generated image data ID to the inkjet printer 20. The ink jet printer 20 performs a printing operation based on the print data received from the computer 88. In this case, the inkjet printer 20 and the computer 88 as a whole correspond to the printing apparatus according to the present invention.

  In each of the above embodiments, a part of the configuration realized by hardware may be replaced by software, and conversely, a part of the configuration realized by software may be replaced by hardware. Also good.

  In addition, when part or all of the functions of the present invention are realized by software, the software (computer program) can be provided in a form stored in a computer-readable recording medium. In the present invention, the “computer-readable recording medium” is not limited to a portable recording medium such as a flexible disk or a CD-ROM, but an internal storage device in a computer such as various RAMs and ROMs, a hard disk, etc. It also includes an external storage device fixed to the computer.

DESCRIPTION OF SYMBOLS 20 ... Inkjet printer 22 ... Motor 24 ... Carriage motor 26 ... Platen 28 ... Print head 30 ... Carriage 34 ... Sliding shaft 36 ... Drive belt 38 ... Pulley 39 ... Position detection sensor 40 ... Control circuit 41 ... CPU
DESCRIPTION OF SYMBOLS 43 ... Internal memory 45 ... Printer driver 47 ... Print data generation part 52 ... Head drive circuit 54 ... Motor drive circuit 56 ... Connector 60 ... Print head unit 88 ... Computer

Claims (7)

A printing device,
A chromatic color nozzle array composed of K (K is an integer of 2 or more) nozzles that discharge chromatic color inks aligned along the first direction, and achromatic color ink aligned along the first direction And an achromatic nozzle array composed of (n · K) nozzles (n is an integer of 2 or more), and arranged side by side along a second direction intersecting the first direction A plurality of nozzle rows,
A moving mechanism for reciprocally moving the plurality of nozzle rows relative to the print medium along the second direction;
A transport mechanism that transports the print medium relative to the plurality of nozzle rows along the first direction;
Based on the print data, an image forming operation for causing the moving mechanism to move the plurality of nozzle rows in the forward and backward directions and ejecting ink to the plurality of nozzle rows; and A controller that forms an image on the print medium by repeating the transport operation to transport,
In the color region including the chromatic color in the image, the control unit performs m times (m is an integer of 1 to n) in which the moving direction of the plurality of nozzle rows is alternately switched between the forward direction and the backward direction. One time in which the moving direction of the plurality of nozzle rows is a specific direction that is one of the forward direction and the backward direction, and both the chromatic color nozzle row and the achromatic color nozzle row are used. A predetermined width along the first direction of the image by m times of the image forming operation including the image forming operation of (m−1) times and only the image forming operation of (m−1) times in which only the chromatic color nozzle row is used. In a monochrome region that does not include a chromatic color in the image, the region of the predetermined width of the image is formed by one image forming operation in which only the achromatic nozzle row is used,
The control unit includes a print data generation unit that generates the print data for specifying an ink discharge mode by each nozzle in each image forming operation based on image data representing an image,
The printing apparatus is a scheduling table that records a position along the first direction of each nozzle and an ink discharge mode in each image forming operation, and configures the achromatic nozzle row (n K) comprising a storage unit for storing a scheduling table having a capacity corresponding to the nozzles;
The printing apparatus, wherein the print data generation unit generates the print data for the chromatic color nozzle array and the print data for the achromatic color nozzle array using the scheduling table sharing a table structure . The printing apparatus according to claim 1,
When the print data generation unit generates the print data for the color area, each of the print resolutions along the first direction of the image forming operation of each achromatic color nozzle subgroup has each of the existence. The (n · K) number of nozzles constituting the achromatic nozzle row are set to be equal to the printing resolution along the first direction of the m image forming operations of the chromatic nozzle row. Grouping into chromatic nozzle subgroups, and generating the print data for the chromatic nozzle row and the print data for each achromatic nozzle subgroup in a common way,
The printing apparatus, wherein the scheduling table has a capacity corresponding to a nozzle constituting each of the achromatic nozzle subgroups. The printing apparatus according to claim 2,
The print data generation unit includes (n · K) nozzles constituting the achromatic nozzle row, and n / m achromatic nozzle subs each including (m · K) nozzles. Printing devices that are grouped into groups. The printing apparatus according to any one of claims 1 to 3,
The control unit performs the first image forming operation in which the moving direction of the plurality of nozzle rows is the specific direction among the m times of image forming operations, between the chromatic color nozzle row and the achromatic color nozzle row. A printing apparatus that performs the image forming operation once in which both are used. The printing apparatus according to any one of claims 1 to 4,
The printing apparatus, wherein the value of n is an even number. A chromatic color nozzle array composed of K (K is an integer of 2 or more) nozzles that discharge chromatic color inks aligned along the first direction, and achromatic color ink aligned along the first direction And an achromatic nozzle array composed of (n · K) nozzles (n is an integer of 2 or more), and arranged side by side along a second direction intersecting the first direction A plurality of nozzle rows, a moving mechanism for reciprocally moving the plurality of nozzle rows relative to the print medium in the second direction, and the print medium with respect to the plurality of nozzle rows. A transport mechanism that relatively transports along a first direction, and a control method for a printing apparatus,
Based on the print data, an image forming operation for causing the moving mechanism to move the plurality of nozzle rows in the forward and backward directions and ejecting ink to the plurality of nozzle rows; and And a process of forming an image on the print medium by repeating a transport operation to transport,
In the step of forming the image, in the color region including the chromatic color in the image, the moving direction of the plurality of nozzle rows is alternately switched between the forward direction and the backward direction (m is an integer of 1 to n) In the image forming operation, the moving direction of the plurality of nozzle rows is a specific direction that is one of the forward direction and the backward direction, and both the chromatic color nozzle row and the achromatic color nozzle row are used. The image forming operation including the one image forming operation and (m-1) times of the image forming operation using only the chromatic color nozzle row is performed along the first direction of the image. Forming a predetermined width region of the image by a single image forming operation in which only the achromatic nozzle row is used in a monochrome region that does not include a chromatic color in the image. And
The control method further includes:
Generating the print data for specifying an ink discharge mode by each nozzle in each image forming operation based on image data representing an image;
A scheduling table for recording a position along each of the nozzles in the first direction and an ink discharge mode in each of the image forming operations, the (n · K) nozzles constituting the achromatic nozzle row Preparing a scheduling table having a capacity corresponding to
The step of generating the print data is a step of generating the print data for the chromatic color nozzle row and the print data for the achromatic color nozzle row using the scheduling table sharing the table structure. There is a control method. A chromatic color nozzle array composed of K (K is an integer of 2 or more) nozzles that discharge chromatic color inks aligned along the first direction, and achromatic color ink aligned along the first direction And an achromatic nozzle array composed of (n · K) nozzles (n is an integer of 2 or more), and arranged side by side along a second direction intersecting the first direction A plurality of nozzle rows, a moving mechanism for reciprocally moving the plurality of nozzle rows relative to the print medium in the second direction, and the print medium with respect to the plurality of nozzle rows. A computer program for controlling a printing apparatus comprising: a transport mechanism that relatively transports along a first direction;
Based on the print data, an image forming operation for causing the moving mechanism to move the plurality of nozzle rows in the forward and backward directions and ejecting ink to the plurality of nozzle rows; and A control function for forming an image on the print medium by repeating the transport operation to transport the print device,
In the color function including the chromatic color in the image, the control function is m times (m is an integer of 1 to n) in which the moving direction of the plurality of nozzle rows is alternately switched between the forward direction and the backward direction. One time in which the moving direction of the plurality of nozzle rows is a specific direction that is one of the forward direction and the backward direction, and both the chromatic color nozzle row and the achromatic color nozzle row are used. A predetermined width along the first direction of the image by m times of the image forming operation including the image forming operation of (m−1) times and only the image forming operation of (m−1) times in which only the chromatic color nozzle row is used. In the monochrome area that does not include a chromatic color in the image, the area of the predetermined width of the image is formed by one image forming operation in which only the achromatic nozzle row is used.
The computer program further includes:
A print data generation function for generating the print data for specifying an ink discharge mode by each nozzle in each image forming operation based on image data representing an image;
A scheduling table for recording a position along each of the nozzles in the first direction and an ink discharge mode in each of the image forming operations, the (n · K) nozzles constituting the achromatic nozzle row And a function of preparing a scheduling table having a capacity corresponding to the printing device,
The print data generation function is a function of generating the print data for the chromatic color nozzle row and the print data for the achromatic color nozzle row using the scheduling table sharing a table structure . Computer program.

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