JP2013136250A - Printing apparatus and printing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To control decrease of the color development of each color when printing using different kinds of ink in a printing system to print the image by discharging the ink.SOLUTION: The printing apparatus includes a print head, wherein a first nozzle row in which a plurality of first nozzles that can discharge the first ink are arranged and a second nozzle row in which a plurality of second nozzles that can discharge the second ink are arranged opposing along the sub-scanning direction. When forming the dot to the end area along the main scanning direction of the print medium, the printing apparatus performs the end treatment to change the arrangement of the first nozzle group in the first nozzle row, and the configuration of the nozzle, and the arrangement of the second nozzle group in the second nozzle row, and configuration of the nozzle for each main scanning of the print head to supplement the decreased amount of the sub scanning, while decreasing the amount of the sub scanning of the print head more than the amount of the sub scanning in areas other than the end area.

Description

  The present invention relates to a technique for printing an image on a print medium.

  2. Description of the Related Art Conventionally, in the field of electrophotography, a technique has been proposed in which a solid layer is formed with a metallic toner in an area where a metallic color is designated, and then a high-definition or rough process color toner layer is formed thereon. (See Patent Document 1). In this technique, metallic colors of various tones are reproduced by printing process color toner on metallic toner.

  Color printing technology using toner includes a tandem method and a four-cycle method, and any of these methods is a method in which toner of each color is superimposed and printed. Therefore, as described above, it is relatively easy to print the process color toner on the metallic toner.

  However, in the field of ink jet printers, printing is performed by ejecting ink of each color from a head to a printing medium almost simultaneously. Therefore, for example, when special glossy ink such as metallic ink and normal color ink are ejected at the same time, the ink is mixed on the print medium, and the intended glossiness and color development may not be obtained. In order to avoid such problems, it is possible to divide the inkjet printing process into a process for printing special glossy ink and a process for printing color ink, and print them in layers. There is a possibility that new problems such as a decrease in speed, an increase in man-hours, and a positional deviation between the first printing and the second printing may occur.

JP 2006-50347 A

  In consideration of these problems, the problem to be solved by the present invention is that, in a printing method in which an image is printed by ejecting ink, the color developability of each color decreases when printing using different types of ink. It is to suppress.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms or application examples.

Application Example 1 A printing apparatus that performs printing by driving a print head relatively in a main scanning direction that is the width direction of a print medium and a sub-scanning direction that intersects the main scanning direction.
The first nozzle row in which a plurality of first nozzles capable of ejecting first ink are arranged, and the second nozzle row in which a plurality of second nozzles capable of ejecting second ink are arranged, A print head arranged to face along the sub-scanning direction;
The first nozzle group consisting of the first nozzle actually used in the first nozzle row is set to be more than the second nozzle group consisting of the second nozzle actually used in the second nozzle row. The first ink is disposed in advance in the sub-scanning direction, and the first ink is ejected to the same printing position in advance of the second ink while the print head is main-scanned and sub-scanned. A dot forming section for forming dots on the medium,
The dot forming unit reduces the sub-scanning amount of the print head from the sub-scanning amount in a region other than the end region when forming dots for the end region in the main scanning direction of the print medium, In order to compensate for the reduced sub-scanning amount, the arrangement and nozzle configuration of the first nozzle group in the first nozzle array, and the arrangement and nozzle arrangement of the second nozzle group in the second nozzle array, and A printing apparatus that performs edge processing for changing a nozzle configuration for each main scan of the print head.

  In such a printing apparatus, the first nozzle group that ejects the first ink is disposed in the sub-scanning direction earlier than the second nozzle group that ejects the second ink. This ink can be ejected to the same printing position as the second ink. As a result, drying of the first ink ejected first can be promoted, so that it is possible to prevent the color developability of the first ink and the second ink from deteriorating. Further, in the above printing apparatus, during printing on the edge region of the print medium, the sub-scanning amount of the print head is reduced, and the first nozzle group and the second nozzle group are compensated to compensate for the reduced sub-scanning amount. Change the arrangement and nozzle configuration. Therefore, there is no need to greatly move the print head in the sub-scanning direction when printing on the edge of the print medium. Therefore, dots can be formed at accurate positions.

  The first ink is not essential for printing a general color image or monotone image, and special glossy ink that gives some glossiness to the image can be used. Special glossy inks include, for example, metallic inks that produce metallic luster, inks that have glossy feelings such as pearls and pearls, and irregular reflection after fixing on the surface of the medium, giving a so-called lame or plain feeling. Ink or the like can be used. On the other hand, as the second ink, color inks essential for printing color images and monotone images, such as cyan ink, magenta ink, yellow ink, and black ink, can be used. As the color ink, for example, a dye ink that penetrates into the ink absorption layer of the print medium and develops color in the ink absorption layer can be used.

  [Application Example 2] In the printing apparatus according to Application Example 1, the dot forming unit may include the first nozzle group at the time of forming dots for an end region along the main scanning direction of the print medium. A printing apparatus that performs the edge processing while maintaining a prior relationship with the second nozzle group. With such a printing apparatus, the first ink can be ejected prior to the second ink even during printing on the end region. As a result, drying of the first ink ejected first can be promoted, so that it is possible to prevent the color developability of the first ink and the second ink from deteriorating.

  Application Example 3 In the printing apparatus according to Application Example 2, the dot forming unit may define a boundary between the first nozzle group and the second nozzle group in the first nozzle row and the A printing apparatus that compensates for the reduced sub-scanning amount by moving from the extreme end side of the end area toward the opposite side of the extreme end side in the second nozzle row. In such a printing apparatus, the sub-scanning amount reduced in the edge processing can be reduced by moving the boundary between the first nozzle group and the second nozzle group in the first and second nozzle rows. Can be supplemented.

  [Application Example 4] The printing apparatus according to any one of Application Example 1 to Application Example 3, wherein the dot forming unit has a total amount of sub-scanning amount reduced during the edge processing prior to the formation of the dots. A printing apparatus that moves the print head in the sub-scanning direction in advance. With such a printing apparatus, it is possible to start forming dots after the print medium has entered deep into the print head. Therefore, it is possible to prevent the edge of the print medium from floating or sinking at the start or end of printing, and it is possible to form dots at accurate positions.

  [Application Example 5] The printing apparatus according to any one of Application Example 1 to Application Example 4, wherein the first ink has optical characteristics after being printed on the surface of the print medium, the reflection angle dependency of which is obtained. A printing device that has special glossy ink. With such a printing apparatus, it is possible to print images having various appearances according to the angle at which the light reflected from the print medium is observed.

  Application Example 6 The printing apparatus according to any one of Application Examples 1 to 5, wherein the first ink is an ink containing a pigment that develops a metallic feeling. With such a printing apparatus, it is possible to print an image having a metallic gloss.

  The present invention can be configured as a printing method or a computer program in addition to the configuration as the printing apparatus described above. The computer program may be recorded on a computer-readable recording medium. As the recording medium, for example, various media such as a flexible disk, a CD-ROM, a DVD-ROM, a magneto-optical disk, a memory card, and a hard disk can be used.

1 is a diagram illustrating a schematic configuration of a printing system 10 as an embodiment of the present invention. It is a figure which shows the image data IMG containing color single area | region A1 and special glossy area | region A2. It is a figure which shows the general dither mask D1. 1 is a diagram illustrating a schematic configuration of a computer 100. FIG. 2 is a diagram illustrating a configuration of a printer 200. FIG. It is a figure which shows a mode that a nozzle position is changed according to a printing area | region. FIG. 3 is a diagram illustrating how dots are formed by a printer. It is a figure which shows the special dither mask D2 for color inks. It is a figure which shows the halftone result when the dot generation rate is 10% using the special dither mask D2. It is a figure which shows the halftone result when the dot generation rate is 25% using the special dither mask D2. It is a figure which shows special dither mask D2b which shifted special dither mask D2 by 1/2 period to the vertical direction. 3 is a flowchart of print processing executed by a computer 100. It is a flowchart which shows a halftone process routine. It is a figure which shows the dot recording rate table T1. It is a figure which shows the dot recording rate table T2. It is a figure which shows the concept of an edge process. It is a figure which shows the mode of the movement of a nozzle row | line | column when not performing an edge part process in the Example after 2nd Example. The mode of movement of the nozzle row and the mode of change of the nozzle configuration are shown in the end processing of the second embodiment. The mode of movement of the nozzle row and the mode of change of the nozzle configuration are shown in the end processing of the third embodiment. The state of movement of the nozzle row and the state of change of the nozzle configuration are shown in the end processing of the fourth embodiment. The state of movement of the nozzle row and the state of change of the nozzle configuration are shown in the end processing of the fifth embodiment. The state of movement of the nozzle row and the state of change of the nozzle configuration are shown in the end processing of the sixth embodiment. The state of the movement of the nozzle row and the state of the change of the nozzle configuration are shown in the end processing of the seventh embodiment. It is a figure which shows the printing result by a 1st modification. It is a figure which shows the printing result by a 2nd modification. It is a figure which shows the printing result by a 3rd modification. It is a figure which shows the printing result by a 4th modification. It is a figure which shows the printing result by a 5th modification. It is a figure which shows the example in which the preceding nozzle group and the succeeding nozzle group partially overlapped. It is a figure which shows the example which the unused nozzle intervened between the preceding nozzle group and the succeeding nozzle group. It is a figure which shows the example which the position in the sub scanning direction of each nozzle which discharges metallic ink and each nozzle which discharges color ink has shifted | deviated.

Hereinafter, embodiments of the present invention will be described in the following order based on examples.
A. First embodiment:
A-1. General configuration of the printing system:
A-2. Computer and printer configuration:
A-3. Nozzle placement control with dither mask:
A-4. Printing process:
A-5. Halftone processing:
A-6. Edge treatment:
B. Second embodiment:
C. Third embodiment:
D. Fourth embodiment:
E. Example 5:
F. Example 6:
G. Seventh embodiment:
H. Variations:

A. First Example A-1. General configuration of the printing system:
FIG. 1 is a diagram showing a schematic configuration of a printing system 10 as an embodiment of the present invention. As shown in the figure, the printing system 10 of this embodiment includes a computer 100 and a printer 200 that actually prints an image under the control of the computer 100. The printing system 10 functions as a printing device in a broad sense as a whole.

  The printer 200 of this embodiment includes a cyan ink (C), a magenta ink (M), a yellow ink (Y), and a black ink (K), which are dye-based color inks. Thus, in this embodiment, the term “color ink” is meant to include black ink. Of course, the printer 200 may include color inks such as light cyan, light magenta, dark yellow, and red in addition to these colors.

  The printer 200 further includes a metallic ink (S) containing a pigment exhibiting a metallic feeling as a special glossy ink. In this embodiment, an oil-based ink composition containing a metal pigment, an organic solvent, and a resin is used as the metallic ink. In order to effectively produce a metallic luster, the above-mentioned metal pigment is a tabular grain, and when the major axis on the plane of the tabular grain is X, the minor axis is Y, and the thickness is Z A 50% average particle diameter R50 of the equivalent circle diameter determined from the area of the XY plane of the tabular grains is 0.5 to 3 μm and satisfies the condition of R50 / Z> 5. Such a metal pigment can be formed of, for example, aluminum or an aluminum alloy, or can be formed by crushing a metal vapor-deposited film. The concentration of the metal pigment contained in the metallic ink can be 0.1 to 10.0% by weight. Of course, the metallic ink is not limited to such a composition, and any other composition can be appropriately employed as long as the metallic gloss is generated.

  When metallic ink is printed on a print medium, light is reflected from the portion and observed. That is, it can be said that the metallic ink has a reflection angle dependency in optical characteristics after being printed on the surface of the printing medium. The metallic feeling caused by the printing of the metallic ink can be expressed by various indexes according to the reflection angle dependency. For example, a known index value In1 represented by the following formula (1) can be used as an index of metallic feeling. This index value In1 measures the lightness of reflected light at three different places defined in the equation (1) when the print medium is irradiated from an angle of −45 degrees, and the relationship between the lightness values obtained at these three places. Can be obtained from

  In addition, the index value In2 of the following equation (2), the index value In3 represented by the following equation (3), and the like can also be used as an index of metallic feeling.

  A predetermined operating system is installed in the computer 100 shown in FIG. 1, and the application program 20 operates under this operating system. A video driver 22 and a printer driver 24 are incorporated in the operating system. The application program 20 inputs image data IMG from the digital camera 120 through the peripheral device interface 108, for example. Then, the application program 20 displays an image represented by the image data IMG on the display 114 via the video driver 22. Further, the application program 20 outputs the image data IMG to the printer 200 via the printer driver 24. Image data IMG input from the digital camera 120 by the application program 20 is data composed of three color components of red (R), green (G), and blue (B).

  The application program 20 according to the present embodiment includes an area composed of three primary colors of R, G, and B (hereinafter referred to as “color single area A1”), and a metallic color as a background color, and the three primary colors of R, G, and B thereon. It is possible to generate image data including a region (hereinafter referred to as “special gloss region A2”) on which a color image composed of This image data is configured by adding information indicating the range of the special glossy area A2 (hereinafter, range information) to normal RGB format image data. The range information can be expressed in a vector format or a raster format.

  FIG. 2 shows an example of the image data IMG including the color single area A1 and the special gloss area A2. In the example shown in FIG. 2, a figure representing a circle and a triangle is designated as the special glossy area A2, and the background is designated as the color single area A1.

  The printer driver 24 corresponding to the “acquisition unit” and “printing control unit” of the present application includes an image acquisition module 40, a color conversion module 42, a halftone module 44, and a print data output module 46. The image acquisition module 40 acquires image data to be printed from the application program 20.

  The color conversion module 42 refers to the color conversion table LUT prepared in advance, and the printer 200 determines the color components R, G, and B of the color portions in the color single area A1 and the special gloss area A2 in the image data. This is converted into expressible color components (cyan (C), magenta (M), yellow (Y), and black (K)).

  The halftone module 44 performs a halftone process in which the image data after color conversion is represented by a binarized (more precisely, multivalued) dot distribution. In this embodiment, a known systematic dither method is used as the halftone process. As the halftone process, an error diffusion method, a density pattern method, and other halftone techniques can be used in addition to the systematic dither method.

  The halftone module 44 of this embodiment includes an area determination module 45. The area determination module 45 determines the special gloss area A2 and the color single area A1 from the image data IMG acquired from the application program 20. Specifically, the area determination module 45 determines the area included in the range information added to the image data IMG as the special gloss area A2, and determines the other part as the color single area A1.

  When the area determination module 45 determines the special gloss area A2 and the color single area A1 in the image data, the halftone module 44 performs halftone processing using a different dither mask depending on the determined area. The dither mask used in the color single region A1 is a general dither mask having blue noise characteristics (hereinafter referred to as “general dither mask D1”).

  FIG. 3 shows an example of the general dither mask D1. Each element of the general dither mask D1 is provided with a threshold value so that when the image is binarized using the general dither mask D1, the image has blue noise characteristics. On the other hand, the dither mask used in the special glossy area A2 is a special dither mask generated to form metallic dots prior to the color dots (hereinafter referred to as “special dither mask D2”). A specific example of the special dither mask D2 will be described later in detail.

  The print data output module 46 rearranges the data representing the dot arrangement of each color obtained by the halftone process in accordance with the dot formation order by the print head 241 of the printer 200 and outputs the data to the printer 200 as print data.

  In this embodiment, the printer driver 24 discriminates the special glossy area A2 and the color single area A1 from the image data, prints the former area using metallic ink and color ink, and the latter area. Is printed using only color ink. The metallic color is not generated by color conversion from each value of R, G, and B by the color conversion module 42, but for the special glossy area A2 represented by the range information added to the image data by the application program 20. Used. That is, in this embodiment, the metallic ink is used based on specific design requirements such as the background color of the label sheet and the background color of the pattern to be conspicuous, rather than being used for reproducing natural images.

A-2. Computer and printer configuration:
FIG. 4 is a diagram illustrating a schematic configuration of the computer 100. The computer 100 is a well-known computer configured by connecting a ROM 104, a RAM 106, and the like with a bus 116 around a CPU 102.

  The computer 100 includes a disk controller 109 for reading data such as the flexible disk 124 and the compact disk 126, a peripheral device interface 108 for exchanging data with peripheral devices, and a video interface 112 for driving the display 114. It is connected. A printer 200 and a hard disk 118 are connected to the peripheral device interface 108. Further, if the digital camera 120 or the color scanner 122 is connected to the peripheral device interface 108, it is possible to perform image processing on an image captured by the digital camera 120 or the color scanner 122. If the network interface card 110 is installed, the computer 100 can be connected to the communication line 300 to obtain data stored in the storage device 310 connected to the communication line. When the computer 100 obtains image data to be printed, the printer driver 24 controls the printer 200 to print the image data.

  Next, the configuration of the printer 200 will be described with reference to FIG. As shown in FIG. 5, the printer 200 includes a transport mechanism that transports the print medium P by the paper feed motor 235, a main scanning mechanism that reciprocates the carriage 240 in the axial direction of the platen 236 by the carriage motor 230, and the carriage 240. A mechanism for driving the mounted print head 241 to eject ink and forming dots, and a control circuit 260 that controls the exchange of signals with the paper feed motor 235, the carriage motor 230, the print head 241, and the operation panel 256. It is composed of

  The main scanning mechanism for reciprocating the carriage 240 in the axial direction of the platen 236 is an endless unit between the carriage motor 230 and a slide shaft 233 that is installed in parallel with the platen 236 axis and slidably holds the carriage 240. A pulley 232 for extending the drive belt 231 and a position detection sensor 234 for detecting the origin position of the carriage 240 are included.

  On the carriage 240, a color ink cartridge 243 that contains cyan ink (C), magenta ink (M), yellow ink (Y), and black ink (K) as color inks is mounted. The carriage 240 is mounted with a metallic ink cartridge 242 containing metallic ink (S). In the print head 241 provided at the lower part of the carriage 240, nozzle rows 244 to 248 for ejecting ink are formed for each color. When the ink cartridges 242 and 243 are mounted on the carriage 240 from above, ink can be supplied from each cartridge to the nozzle rows 244 to 248. Note that each nozzle formed on the print head 241 can eject large, medium, and small ink droplets as described later, and can form large, medium, and small dots on the print medium. Taking large dots as a reference, medium dots have about half the ink amount of large dots, and small dots have about 1/4 ink amount.

  The control circuit 260 is configured by connecting a CPU, a ROM, a RAM, a PIF (peripheral device interface), and the like with a bus. When the control circuit 260 receives the print data output from the computer 100 via the PIF, the control circuit 260 drives the carriage motor 230 to move the ink ejection heads 244 to 247 for each color in the main scanning direction with respect to the print medium P. The print medium P is moved in the sub-scanning direction by reciprocating and driving the paper feed motor 235. The control circuit 260 performs printing by driving the nozzles at an appropriate timing based on the print data in accordance with the movement of the carriage 240 reciprocally (main scanning) or the movement of paper feeding of the printing medium (sub scanning). Ink dots of appropriate colors are formed at appropriate positions on the medium P. In this way, the printer 200 can print a color image on the print medium P. In this embodiment, the print medium is transported in the sub-scanning direction, but the position of the print medium may be fixed and the carriage 240 may be transported in the sub-scanning direction.

  As shown in FIG. 5, the control circuit 260 includes an end processing module 262. The end processing module 262 is a module realized by the CPU in the control circuit 260 executing a predetermined program stored in the ROM. The edge processing module 262 adjusts the paper feed amount and the main scanning order for the upper end region and the lower end region along the main scanning direction of the print medium, so that margins are generated at the upper end portion and the lower end portion of the print medium. The process which suppresses is performed. Hereinafter, such processing is referred to as “end processing”. In this edge processing, the edge processing module 262 stores in advance the paper feed amount for each main scan (for example, 1, 1, 1, 7, 7, 7, 7,... In the example of FIG. 16). At the same time, it is stored in advance what number of main scans each nozzle is responsible for forming which position of which raster line. Then, according to the stored information, the paper feed amount and the main scanning order are adjusted to perform printing on the edge region.

When printing an image, the printer 200 according to the present embodiment performs printing by changing the positions of the actually used nozzles in the color single region A1 and the special glossy region A2 among the plurality of prepared nozzles.
FIG. 6 shows how the nozzle position is changed according to the print area. FIG. 6A shows the arrangement of the nozzles when printing the color single area A1, and FIG. 6B shows the arrangement of the nozzles when printing the special glossy area A2. In the figure, black circles indicate nozzles that are actually used among nozzles that can eject metallic ink, and hatched circles indicate nozzles that are actually used among nozzles that can discharge color ink. Show. White circles indicate nozzles that are not actually used. As shown in these drawings, the print head 241 includes a nozzle row having nozzles capable of ejecting metallic ink and a nozzle row having nozzles capable of ejecting color ink substantially facing each other in the sub-scanning direction. Has been placed.

  As shown in FIG. 6A, in the color single area A1, the printer 200 does not use the nozzles prepared for discharging the metallic ink, but uses all the nozzles prepared for discharging the color ink. And print. On the other hand, in the special glossy area A2, the printer 200 selects seven nozzles (hereinafter referred to as “preceding nozzle group”) that first pass through the print medium P among the 14 nozzles for discharging the metallic ink. It is used during actual printing, and the remaining seven are not used. For the color ink (C, M, Y, K) nozzle rows 244 to 247, of the 14 nozzles, the seven nozzles that pass through the print medium first are not used, and the remaining seven are used. The remaining seven nozzles are used (hereinafter referred to as “following nozzle group”). In this way, in this embodiment, when the special glossy area A2 is printed, the preceding nozzle group and the succeeding nozzle group are arranged at a predetermined interval in the sub-scanning direction as shown in FIG. On the same area of the print medium P, the metallic ink is ejected first in time, and the color ink is ejected later in time.

  As is apparent from FIGS. 6A and 6B, in this embodiment, the metallic portion and the color portion in the special glossy area A2 are more than the number of nozzles used in the single color area A1, respectively. Printing is performed with a small number of nozzles (specifically, the number of nozzles is ½). Therefore, the number of main scans of the print head 241 for filling a predetermined local area in the color single area A1 with color ink is the same as the printing for filling the local area of the same size in the special glossy area A2 with color ink or metallic ink. This is greater than the number of main scans of the head 241 (specifically, twice as many).

A-3. Nozzle placement control with dither mask:
In the control for changing the arrangement of the nozzles actually used according to the area to be printed, a special dither mask (special dither mask D2) is applied to the special glossy area A2 during the halftone processing by the printer driver 24. It is realized with. This principle will be described in detail below.

  In this embodiment, first, as an aspect of drive control of the print head 241, the overlap number is “2”, the nozzle pitch is “2”, and the paper feed amount is “7”. It was decided to perform bidirectional printing in which ink was ejected at both times. The number of overlaps refers to the number of times of main scanning necessary to fill all the lines formed in the main scanning direction (horizontal direction) with dots. That is, when the overlap number is “2”, one line in the main scanning direction is completed in two main scans. The nozzle pitch means the number of lines (dots) existing between two nozzles. In this embodiment, since the nozzle pitch is “2”, dots are formed every other line in the main scanning of the print head 241 once. The paper feed amount refers to the amount (number of lines) by which the print head 241 is conveyed in the sub-scanning direction for each main scanning. In this embodiment, since the paper feed amount is “7”, that is, an odd number of paper feed amounts, a new dot is formed in the next main scan in the gap between dots formed in advance every other line. It will follow.

  FIG. 7 is a diagram illustrating how dots are formed by the printer 200. Here, first, it is assumed that the metallic ink can be ejected from only the first seven nozzles in the sub-scanning direction and cannot be ejected from the remaining seven nozzles of the nozzle array composed of 14 nozzles. Further, it is assumed that the color ink cannot be ejected from the first seven lines, and can be ejected only from the remaining seven lines. For convenience of illustration, it is assumed that the metallic nozzle group and the color nozzle group are included in the same nozzle row. FIG. 7A shows a state in which such a nozzle row moves in the sub-scanning direction every time main scanning is performed. In the nozzle row shown in FIG. 7 (a), the portion indicating the numerical value from 1 to 7 indicates the nozzle from which the color ink is ejected, and the portion indicating the numerical value from 8 to 14 is the metallic ink. Indicates a nozzle to be discharged. As shown in FIG. 7A, in this embodiment, since the paper feed amount is set to “7”, the print head 241 moves 7 lines (7 nozzles) in the sub-scanning direction for each main scan. ing.

  FIG. 7B shows how many main scans each dot formed on the print medium is formed. Each grid shown in FIG. 7B represents one dot on the print medium, and the numerical value in the grid corresponds to the main scanning number shown in the upper part of FIG. 7A. That is, according to FIG. 7B, it can be seen that in the uppermost line, odd-numbered dots are formed by the first main scanning and even-numbered dots are formed by the third main scanning.

  As shown in FIG. 7B, in this embodiment, when a 2 × 2 local region (hereinafter referred to as a local region) is viewed, each dot in the local region is represented by upper left, lower left, upper right. It is filled in the order of the lower right. This order is called “filling order”. Regarding the size of the local area, the horizontal direction (main scanning direction) matches the number of overlaps (“2” in this embodiment), and the vertical direction (sub-scanning direction) corresponds to the nozzle pitch (“2” in this embodiment). Match. The filling order has a property of changing every time the print head 241 is moved in the sub-scanning direction (that is, every time main scanning is performed). In this embodiment, the filling order changes four times. Then, it returns to the original filling order. The filling order is set by the printer driver 24 giving a predetermined command to the control circuit 260 of the printer 200. When receiving the setting of the filling order from the printer driver 24, the control circuit 260 forms dots according to the order set in the filling order.

  FIG. 7C shows which nozzles form each dot formed on the print medium. The numerical value in each lattice corresponds to the nozzle number shown in FIG. When FIG. 7C and FIG. 7B are taken together, the odd-numbered dots in the uppermost line in the figure are formed by the 11th nozzle in the first main scanning, and are even-numbered. It can be seen that the second dot is formed by the fourth nozzle in the third main scan. For the second line, odd-numbered dots are formed by the eighth nozzle in the second main scan, and even-numbered dots are formed by the first nozzle in the fourth main scan. I understand that.

  FIG. 7C shows dots formed by nozzles having nozzle numbers 8 to 14, that is, nozzles for metallic ink, in a black lattice, and nozzles having nozzle numbers 1 to 7, that is, color. The dots formed by the ink nozzles are indicated by a white grid. In this way, when the dots formed by the metallic ink and the dots formed by the color ink are displayed in different colors, the color ink nozzles and the metallic ink nozzles are arranged in the head while being shifted in the sub-scanning direction. In this case, it can be seen that a specific pattern (pattern) appears on the print medium. The pattern shown in FIG. 7C changes one after another in units of 7 lines (hereinafter referred to as “band units”), which is a unit of the paper feed amount. This pattern has a property of returning to the initial pattern every time the filling order changes.

  As described above, here, the metallic ink can be ejected from only the preceding seven of the 14 nozzle nozzle rows, and the color ink can be ejected from only the following seven. Assumed. However, considering the result of FIG. 7C, conversely, as long as the pattern shown in FIG. 7C is printed, the metallic ink is ejected from only the first seven nozzles out of the 14 nozzles. In other words, the color ink is discharged only from the subsequent seven nozzles. That is, if a dither mask in which a pattern as shown in FIG. 7C appears by halftone processing is prepared in advance as a special dither mask D2, the nozzle arrangement pattern can be changed by simply switching the dither mask to be used. It can be done.

  FIG. 8 shows an example of a special dither mask D2 for color ink used in this embodiment. As shown in FIG. 8, the special dither mask D2 of this embodiment is generated based on the pattern shown in FIG. The size of the special dither mask D2 in the horizontal direction is an integral multiple of the number of overlaps (in this embodiment, “16” which is 8 times), and the vertical size is an integral multiple of the pattern shown in FIG. (In the present embodiment, it is 1 times “28”). If this special dither mask D2 is a normal dither mask, threshold values from 1 to 488 (= 16 * 28) are arranged for each element. Therefore, the data in the range from 0 to 488 can be binarized by turning off the dots when the data to be compared is less than the threshold and turning on the dots when the data to be compared is greater than or equal to the threshold. However, the special dither mask D2 for color ink shown in FIG. 8 has substantially threshold values only at positions corresponding to the white grid shown in FIG. 7C (that is, positions where color dots are formed). Is arranged. At a position corresponding to the black grid shown in FIG. 7C (that is, a position where a metallic dot is formed), a value exceeding the maximum value of the dot recording rate compared with the threshold value of the special dither mask D2 is present. Is set. Thus, if a value exceeding the maximum value of the dot recording rate is set for the position where the metallic dot is formed, no dot is formed for that portion. Therefore, if the special dither mask D2 shown in FIG. 8 is used, only color dots can be formed. Even if a special code is arranged in the hatched portion in FIG. 8 and the processing for comparing the threshold value is skipped for the portion where the code is recorded during the halftone processing, dot formation for the portion is performed. Can be suppressed. In FIG. 8, only threshold values of 112 or less are displayed, and illustration of all threshold values is omitted.

  FIG. 9 shows a halftone result when the dot recording rate is 10% using the special dither mask D2 shown in FIG. FIG. 10 shows a halftone result when the dot recording rate is 25%. As shown in these drawings, if the arrangement of the thresholds on the special dither mask D2 is optimized, even if the special dither mask D2 generates a pattern as shown in FIG. Up to this, it becomes possible to ensure good dot dispersibility.

  FIG. 8 shows a special dither mask D2 for color ink (hereinafter referred to as “special dither mask D2a”). In this embodiment, the special dither mask D2a is ½ cycle in the vertical direction. The shifted dither mask is used as a special dither mask for metallic ink (hereinafter referred to as “special dither mask D2b”). In the pattern shown in FIG. 7 (c), the metallic portion and the color portion are completely interchanged with each other in half in the vertical direction. Therefore, by shifting the special dither mask D2a by 1/2 period in the vertical direction, this threshold value arrangement can be used as it is for metallic ink. FIG. 11 shows an example of the special dither mask D2b obtained by shifting the special dither mask D2a in the vertical direction by ½ period in this way. Comparing FIG. 8 with FIG. 11, the special dither mask D2a for color ink and the special dither mask D2b for metallic ink are in exclusive positions except for the hatched portion that does not substantially function as a threshold value. A threshold is arranged. Therefore, in the special glossy area A2 to which these dither masks are applied, the dots made of metallic ink and the dots made of color ink are formed at exclusive positions.

  The computer 100 individually stores these two types of special dither masks D2a and D2b in advance. That is, the computer 100 performs halftone processing by properly using three types of dither masks: a general dither mask D1, a special dither mask for color ink D2a, and a special dither mask for metallic ink D2b. Hereinafter, a printing process for performing printing using these dither masks will be described in detail.

A-4. Printing process:
FIG. 12 is a flowchart of print processing executed by the computer 100 according to this embodiment. This printing process is performed by the CPU 102 as hardware executing a program prepared as the printer driver 24. When this printing process is started, the computer 100 first inputs RGB format image data including the color single area A1 and the special glossy area A2 from the application program 20 (step S100). As described above, the range of the special glossy area A2 is added to the image data as range information.

  When the image data is input, the computer 100 uses the color conversion module 42 to convert the RGB format image data input in step S100 into CMYK format image data (step S200). By this color conversion processing, the color single area A1 and the color portion of the special glossy area A2 are converted from the RGB format to the CMYK format.

  When the CMYK format image data is obtained, the computer 100 uses the halftone module 44 to perform halftone processing for each color of cyan (C), magenta (M), yellow (Y), black (K), and metallic (S). Tone processing is performed to generate data that can be transferred to the printer 200 (step S300). The data that can be transferred to the printer 200 is data (referred to as dot data) indicating the size of ink droplets that the printer 200 forms on the print medium P, and it indicates whether or not to form small dots, medium dots, or large dots. It is data.

  In the present embodiment, it is assumed that the metallic color printed in the special glossy area A2 is uniformly subjected to halftone processing at a density of 25% in the processing of step S300 described above. This concentration can be appropriately selected by the user. For example, a user interface capable of specifying the density of the metallic color printed in the special glossy area A2 is provided on the setting screen of the printer driver 24, and the user can appropriately set the user interface. Alternatively, the user may set the density according to the function of the application program 20, and the application program 20 may record the value as additional information in the image data. The printer driver 24 can determine the density of the metallic ink to be printed in the special glossy area A2 by referring to this additional information.

  When the halftone process ends, the computer 100 outputs the dot data for C, M, Y, K, and S generated by the halftone process to the printer 200 as print data using the print data output module 46. (Step S400).

  The printer 200 receives print data output from the computer 100, and prints an image by ejecting ink onto a print medium according to the received print data. In this embodiment, the printer 200 basically sets the number of overlaps to “2”, the nozzle pitch to “2”, the paper feed amount to “7”, and performs bi-directional printing. The printing mechanism such as the motor 230 and the paper feed motor 235 is controlled. However, edge processing is executed by the edge processing module 262 for the upper edge and lower edge of the print medium, and the paper feed amount is adjusted by the printer 200.

A-5. Halftone processing:
Of the print processing described above, details of the halftone processing executed in step S300 will be described in detail below.
FIG. 13 is a flowchart showing a halftone processing routine. This halftone process is performed for each color of C, M, Y, K, and S. As shown in the figure, when this process is started, first, the computer 100 performs a process of reading gradation data of the pixel of interest (step S302). The initial position of the pixel of interest is the upper left corner of the image data. As described above, it is assumed that the gradation data of the metallic color is uniformly 25% during the halftone processing of the metallic color.

  When the gradation data of the pixel of interest is read (step S302), the computer 100 refers to the range information attached to the image data to determine whether the position of the pixel of interest is included in the special glossy area A2. Judgment is made (step S304). If it is determined that it is not included in the special glossy area A2 (in other words, if it is determined that it is included in the color single area A1), the computer 100 performs processing for selecting the dot recording rate table T1 (step S306). ), A process of selecting the general dither mask D1 is performed (step S408). The “dot recording rate table” is a table in which the occurrence rates of small, medium, and large dots that are generated in the pixel in accordance with the gradation data of the pixel of interest are defined. A specific example of this table will be described later.

  If it is determined in step S304 that the position of the pixel of interest is included in the special glossy area A2, the computer 100 performs processing for selecting the dot recording rate table T2 (step S310), and further, the color currently being processed. Is determined to be metallic (step S312). If the color being processed is metallic, the computer 100 selects the special dither mask D2b for metallic (step S314), and if it is another color (C, M, Y, K), the special dither for color is selected. The mask D2a is selected (step S316).

  14 and 15 show examples of the dot recording rate tables T1 and T2 selected in the above-described processing in step S306 or S310. As shown in FIG. 14, the dot recording rate table T1 defines the formation ratios of large, medium, and small dots for C, M, Y, and K. In this dot recording rate table T1, the recording rate S of small dots gradually increases until the recording rate reaches the maximum in the range of gradation data from 0 to 15, and then the range of gradation data reaches 40. The recording rate is set to gradually decrease until it reaches zero. Similarly, the recording rate M of medium dots gradually increases until the recording rate reaches a maximum in the range of gradation data from 15 to 40, and then becomes 0 in the range of the gradation data up to 80. It is set to decrease gradually. Further, the recording rate L of large dots is set so as to gradually increase until the recording rate reaches the maximum in the range of image data from 40 to 100. Is lower than a range of less than 80).

  On the other hand, in the dot recording rate table T2, as shown in FIG. 15, the recording rate S for small dots is not set, and only the recording rates for medium dots and large dots are set. Specifically, when the gradation data is in the range of 0 to 20, the medium dot recording rate M is gradually increased to about 30% of the maximum value, and then the gradation data is in the range of up to 40, and the recording rate is Decrease until zero. Similarly, the recording rate L of large dots gradually increases until the recording rate reaches the maximum in the range of gradation data from 20 to 100 (exactly, in the range of gradation data of 40 or more, the rate of increase gradually increases). , Lower than the range of 40 or less).

  Here, when the dot recording rate table T1 and the dot recording rate table T2 are compared, all the recording rates of small dots, medium dots, and large dots are set in the dot recording rate table T1, and the dot recording rate table In T2, a recording rate of only medium dots and large dots is set. Therefore, for the same gradation data, a larger dot is formed by using the dot recording rate table T2 than the dot recording rate table T1.

  When the process of selecting a dither mask is performed in any one of steps S308, S314, and S316, the computer 100 corresponds to the gradation data read in step S302 from the dot recording rate table selected in step S306 or step S310. Processing for reading the dot recording rate is performed (step S318). Subsequently, the computer 100 reads the threshold value corresponding to the position of the pixel of interest from the dither mask selected in any of steps S308, S314, and S316 (step S320), and the dot recording rate read in step S318 and step S320. The binarization is performed by the systematic dither method using the threshold value read in (step S322). Since the systematic dither method is a well-known technique, a detailed description is omitted, but in short, the recording rate corresponding to the gradation data of the target pixel is compared with the threshold value in the dither mask corresponding to the position of the target pixel. If the recording rate is higher, a dot is formed on the pixel, and if the recording rate is lower, it is determined that no dot is formed.

  With reference to the dot recording rate table T1 or the dot recording rate table T2, the recording rates of two or more types of dots may be read. For example, in the dot recording rate table T1 of FIG. 14, two types of recording are performed such that the recording rate S for small dots is “48” and the recording rate M for medium dots is “16” with respect to the gradation data CS1. The rate is read. In such a case, the computer 100 determines the size of the dot formed for the pixel of interest by the following procedure.

(1) First, the large dot recording rate L is compared with a threshold value. If the large dot recording rate L is larger than the threshold value, it is determined that a large dot is to be formed at the target pixel.
(2) If the recording rate L for large dots is smaller than the threshold value, the sum (L + M) of the recording rate L for large dots and the recording rate M for medium dots is compared with the threshold value. As a result, if this sum (L + M) is larger than the threshold value, it is determined that a medium dot is to be formed in the target pixel.
(3) If the sum (L + M) is smaller than the threshold, the sum (L + M + S) of the recording rate of large dots, the recording rate of medium dots, and the recording rate of small dots is compared with the threshold. As a result, if this sum (L + M + S) is larger than the threshold value, it is determined that a small dot is to be formed on the pixel of interest. On the other hand, if this sum (L + M + S) is smaller than the threshold value, it is determined that no dot is formed on the target pixel.

  Here, it is assumed that the recording rate L for large dots is “0”, the recording rate M for medium dots is “16”, the recording rate S for small dots is “48”, and the threshold is “30”. Then, in the step (1), since the recording rate of large dots is smaller than the threshold value, it is not determined that large dots are formed, and the process proceeds to step (2). In step (2), the sum (L + M) of the large dot recording rate L and the medium dot recording rate M is 16 (= 0 + 16), but the value is still smaller than the threshold (= 30). Go to 3). In step (3), the sum (L + M + S) of the large dot recording rate, the medium dot recording rate, and the small dot recording rate is 64 (= 0 + 16 + 48), which is larger than the threshold (= 30). It is determined to form a dot. In this way, if the recording rate of each dot size is added one after another and compared with the threshold value, it is possible to determine which size of dot is formed with only one threshold value.

  When the halftone process for the target pixel is completed by the process described above, the computer 100 designates the next pixel (step S324), and determines whether the process for all the pixels is completed (step S326). ). If the processing for all the pixels has not been completed, the computer 100 returns the processing to step S302 and repeats the above processing. On the other hand, if the processing has been completed for all the pixels, the halftone process is terminated.

  When the above-described halftone process is completed, the print data generated by the halftone process is transmitted to the printer 200. Upon receiving this print data, the printer 200 drives the print head 241 with the overlap number being “2”, the nozzle pitch being “2”, and the paper feed amount being “7”, as described above. Bidirectional printing is performed to eject ink both during forward movement and during backward movement. Then, as shown in FIGS. 7A and 7B, in the color single region A1, all the nozzles for color ink are used for printing. In the special glossy area A2, metallic ink is printed by the preceding nozzle group, and color ink is printed by the succeeding nozzle group.

A-6. Edge treatment:
Next, end processing executed by the end processing module 262 of the printer 200 will be described. In the following, for the sake of simplicity, it is assumed that the end of the print medium is the special gloss area A2.

  FIG. 16 is a diagram illustrating the concept of end processing in the present embodiment. FIG. 16A shows the movement of the nozzle row and the change in the nozzle configuration during printing in the upper end area of the print medium. FIG. 16B shows a printing result by the edge processing of this embodiment. In FIG. 16A, the part indicated by “x” represents a nozzle that is not used. In this embodiment, first, as shown in FIG. 16A, the printer 200 moves the print head 241 in advance in the sub-scanning direction by 18 dots from the position shown in FIG. Keep it. By doing so, most of the nozzle rows (specifically, the nozzles from No. 2 to No. 14) are positioned on the print medium. The paper feed amount (18 dots) to be moved in advance is determined by the total amount of sub-scanning that is reduced from the normal time during the edge processing described below. Specifically, in the present embodiment, the paper feed amount is 7 at normal time, but the paper feed amount is reduced to “1” at the end processing, and this “1” paper feed is performed three times. The total is 18 dots (= (7-1) * 3).

  If the paper is fed in advance, then the printer 200 performs main scanning while ejecting metallic ink using the 2nd to 5th nozzles according to the print data received from the computer 100. In this way, a dot made of metallic ink is formed on the uppermost end of the print medium. The positions of the 2nd to 5th nozzles correspond to the positions of the 11th to 14th nozzles when the print head 241 is not moved by 18 dots in advance. In other words, the printer 200 moves the print head 241 in the sub-scanning direction by 18 dots in advance by the function of the end processing module 262, so that the dot data originally allocated to the 11th to 14th nozzles can be obtained. Ink is ejected by assigning nozzles 2 to 5. In the present embodiment, the first nozzle is located in a region outside the upper end of the print medium during the first main scanning. Therefore, the first nozzle is not used. In each of the embodiments described below, including this embodiment, the nozzle located outside the print medium is not used, but it is also possible to eject ink from such a nozzle. In this case, the ink ejected to the outside of the printing medium is discarded with respect to a predetermined ink absorber.

  When the first main scan is completed, the printer 200 performs the sub-scan with the paper feed amount set to “1”. In the second main scan, metallic ink is ejected using nozzles 2 to 8. The printer 200 changes the position of the nozzle actually used in the nozzle row so as to compensate for the paper feed amount reduced from “7” to “1”. In this embodiment, as shown in FIG. 16A, in the second main scan, paper is fed by “1” from the first main scan, but when attention is paid to the used nozzles in the nozzle row, The lowest nozzle is moved from No. 5 to No. 8. That is, when viewed from the print medium, as in the normal case, the used nozzles are equivalent to the paper feed amount corresponding to “7” (= (8−5) × 2 [nozzle pitch] +1 [paper feed amount]). Is moved in the sub-scanning direction.

  When the second main scanning is completed, the printer 200 further performs sub-scanning with the paper feed amount set to “1”. In the third main scan, metallic ink is ejected using the 5th to 11th nozzles, and color ink is ejected using the 1st to 4th nozzles. As shown in FIGS. 6 and 7, in this embodiment, the number of metallic nozzles is “7”. Therefore, when seven nozzles from No. 5 to No. 11 are used for discharging metallic ink, the following 1 is used. No. 4 to No. 4 nozzles are used for color ink.

  When the third main scan is completed, the printer 200 further performs the sub-scan with the paper feed amount set to “1”. In the fourth main scan, metallic ink is ejected using the 8th to 14th nozzles, and color ink is ejected using the 1st to 7th nozzles. That is, in the fourth main scan, the main scan is performed with the original nozzle arrangement shown in FIG. As described above, when the configuration of the nozzles used in the nozzle row is changed as described above while feeding paper by “1” in the edge processing, as shown in FIG. The boundary of the nozzle group is moved by “7”, which is the original paper feed amount, as viewed from the print medium, while maintaining the prior and subsequent relationship of the nozzle group. Finally, main scanning is performed with the original nozzle arrangement in the fourth main scanning. When the fourth main scan is completed, as shown in FIG. 16B, printing on the end region of 21 dots from the upper end of the paper is completed. The printer 200 performs sub-scanning with the paper feed amount set to “7” as usual from the next fifth main scanning.

  According to the edge processing described above, the printer 200 starts printing by moving the print head 241 in advance in the sub-scanning direction by 18 dots. That is, printing is performed on the end region in a state where the upper end portion of the print medium is advanced deep into the print head 241. For example, when printing is performed with the upper end portion of the print medium being slightly inserted into the print head 241, depending on the structure of the paper feed mechanism of the printer 200, the end portion of the print medium may float or sink. In some cases, it is difficult to form dots at accurate positions. However, in the edge processing described above, printing can be started with the top edge of the print medium approaching deep into the print head 241, so that the dots are positioned accurately relative to the edge of the print medium. It becomes possible to form. As a result, the image quality of the output image can be improved.

  The printer 200 performs the same process as the above-described end process for the lower end area of the print medium. In other words, when the print head moves to the lower end region of the print medium, the printer 200 uses the end processing module 262 to reduce the paper feed amount while compensating for the reduced paper feed amount. Change the actual nozzle arrangement. By doing so, the printer 200 can form dots at accurate positions also in the lower end area of the print medium. Further, FIG. 16 shows the result of performing the edge processing on the special glossy area A2 existing in the upper end area, but the color single area A1 existing in the upper end area is shown in FIG. All nozzles other than the nozzle indicated by “x” are used as nozzles for discharging color ink. In this way, dots can be formed at accurate positions in the color single region A1 in the end region as in the special gloss region A2.

  In the present embodiment, the paper feed amount at the time of edge processing is adjusted by the edge processing module 262 provided in the printer 200. However, the paper feed amount may be adjusted by the printer driver 24 on the computer 100 side. That is, when the printer driver 24 transmits print data to the printer 200, it simultaneously transmits control data for instructing the paper feed amount. The printer 200 can adjust the paper feed amount by analyzing the control data.

  According to the printing system 10 of the present embodiment described above, since the metallic ink can be printed prior to the color ink in the special glossy area A2, the drying of the metallic ink can be promoted. As a result, mixing of the metallic ink and the color ink is suppressed, so that it is possible to improve the color developability of both the metallic ink and the color ink.

  In the present embodiment, the color single area A1 is printed using more nozzles than the special gloss area A2 (in other words, the special gloss area A2 is filled with dots of color ink or metallic ink. The number of scans in which the color single area A1 is filled with dots of color ink is larger than the number of scans). As a result, since the printing speed for the color single area A1 is improved, the printing speed of the entire image is significantly higher than when all the printing areas are printed by dividing the nozzle from the beginning into the preceding and following groups. Become.

  Furthermore, in this embodiment, the arrangement of nozzles that are actually used can be controlled simply by switching the dither mask used during halftone processing according to the printing area. This eliminates the need for a circuit that gives special control signals to each nozzle to instruct whether or not to use it, and allows the arrangement of the nozzles to be varied without significantly changing the configuration of a conventional printer. become.

  In this embodiment, when printing metallic ink in the special glossy area A2, larger dots are formed by using the dot recording rate table T2. Considering the use of metallic ink, the gradation expression or image reproducibility by the metallic ink in the special glossy area A2 is not so important, so it is not necessary to consider much countermeasures against image quality degradation such as dot graininess and banding. It is. As a result, the amount of metallic ink ejected per unit area increases, so that the range in which metallic dots are formed can be increased even with a small number of scans.

  In this embodiment, the halftone process is performed on the color portion of the special glossy area A2 using the dot recording rate table T1 similar to that of the color single area A1. In contrast, the color portion of the special glossy area A2 is subjected to halftone processing using a dot recording rate table (for example, dot recording rate table T2) in which the size of the used dots is larger than the dot recording rate table T1. It may be done. This is because in the special glossy area A2, since the background is a metallic color, the presence of color ink is not conspicuous in the first place, and it is not necessary to take much measures against image quality deterioration such as graininess and banding. From another viewpoint, for example, the metallic ink in the special glossy area A2 can be printed with small dots, and the color ink can be printed with large dots. By doing so, it becomes possible to make the color ink in the special glossy area A2 more conspicuous than the metallic ink. Of course, the halftone process can also be performed on the special glossy area A2 by using a table similar to the dot recording rate table used in the color single area A1.

B. Second embodiment:
Subsequently, some other embodiments of the edge processing will be described.
FIG. 17 is a diagram illustrating a state of movement of the nozzle row when the end portion processing is not performed in the second and subsequent embodiments. As shown in this figure, in the second and subsequent embodiments, ten nozzles are used for each of the metallic ink discharge and the color ink discharge. In each main scan, the sub-scan is performed with the paper feed amount set to “5”.

  FIG. 18 shows the movement of the nozzle row and the change of the nozzle configuration in the end processing of the second embodiment. In this embodiment, printing is performed on the upper end region of the print medium by the main scanning from the first time to the eighth time. In this embodiment, in the main scan from the first time to the eighth time, the paper feed amount is set to “1” and the sub-scan is performed. As shown in FIG. 18, in this embodiment, metallic ink is ejected using nozzles 4 to 6 in the first main scan. Thereafter, the nozzle arrangement is changed in the nozzle row so as to compensate for the paper feed amount reduced from “5” to “1”. Specifically, in the second main scan, metallic ink is ejected using nozzles 4 to 8, and in the third main scan, metallic ink is ejected using nozzles 3 to 12. In the fourth main scan, metallic is ejected using a total of 10 nozzles from No. 5 to No. 14, and color ink is ejected using No. 2 to No. 4 nozzles. Thus, when the arrangement of the nozzles in the nozzle row is changed, the main scanning is performed with the original nozzle arrangement shown in FIG. 17 in the eighth main scanning.

C. Third embodiment:
FIG. 19 shows the movement of the nozzle row and the change of the nozzle configuration in the end processing of the third embodiment. As shown in the drawing, in this embodiment, the paper feed amount of the sub-scan performed after the first, third, and fourth main scans is “0”. That is, the main scanning performed after these times is performed on the same line as the previous main scanning. Then, after performing such sub-scanning, the order of change in the nozzle configuration is appropriately changed from the order of the second embodiment. Specifically, the nozzle is configured so that the dots (see FIG. 18) to be formed in the second main scan of the second embodiment are formed in the first main scan in the present embodiment. Further, in this embodiment, the nozzle is configured so that dots to be formed by the fourth main scan of the second embodiment are formed by the second main scan. Further, the nozzle is configured so that the dots to be formed in the first main scan in the second embodiment are formed in the third main scan in the present embodiment, and the dots are formed in the main scan in the third time in the second embodiment. In this embodiment, the nozzle is configured to form a power dot in the fourth main scan.

  According to the third embodiment described above, it is possible to perform main scanning without performing sub-scanning after the first, third, and fourth main scanning. Therefore, as can be seen by comparing the positions indicated as “out of paper” in FIGS. 18 and 19, the printing medium can be advanced deeper than the print head 241 to start printing. As a result, it becomes possible to form dots at more accurate positions.

D. Fourth embodiment:
FIG. 20 shows the movement of the nozzle row and the change in the nozzle configuration in the end processing of the fourth embodiment. In this embodiment, in order to reduce the paper feed amount during the edge processing, dots to be formed by the seventh main scan (see FIG. 19) of the third embodiment are formed by the third main scan. The nozzle was configured as follows. In this way, printing can be started by causing the print medium to enter deeper into the print head 241.

E. Example 5:
FIG. 21 shows the movement of the nozzle row and the change of the nozzle configuration in the end processing of the fifth embodiment. In the fourth embodiment, as shown in FIG. 20, in the third main scan, nozzles 7 to 16 are assigned for discharging metallic ink, and nozzles 2 to 6 are used for discharging color ink. Assigned. In contrast, in this embodiment, the nozzle configuration is separated so that the dots formed in the third main scan of the fourth embodiment are formed in two main scans. Specifically, in the third main scan, nozzles 1 to 6 are not used, so that only metallic dots are formed, and the eighth main scan and the ninth scan in the fourth embodiment are performed. The main scan is added once during the main scan (that is, the ninth main scan in this embodiment), and the color dots to be formed in the third main scan at the time of the main scan are the first to fifth. The nozzle is formed. As described above, in this embodiment, by increasing the number of times of main scanning performed during the edge processing, it is possible to prevent some color dots from being formed prior to the formation of metallic dots.

F. Example 6:
FIG. 22 shows the movement of the nozzle row and the change of the nozzle configuration in the end processing of the sixth embodiment. FIG. 22 shows the movement of the nozzle row that allows the print medium to be inserted into the print head 241 deepest and the change in the nozzle configuration. According to the present embodiment, by performing the edge processing with the nozzle arrangement and the paper feed amount as shown in FIG. 22, the printing medium can be inserted deeply into the print head 241 and printing can be started.

G. Seventh embodiment:
FIG. 23 shows the movement of the nozzle row and the change of the nozzle configuration in the end processing of the seventh embodiment. In the sixth embodiment, the state of movement of the nozzle row and the change in the nozzle configuration in which the print medium can be inserted deeply into the print head 241 have been shown, but as shown in FIG. In the third main scan and the fourth main scan, color dots are formed prior to the metallic dots in the fifth and sixth main scans. Therefore, in this embodiment, a part of the color dots to be formed in the main scanning is newly added between the eighth main scanning and the ninth main scanning in the sixth embodiment. It is formed by main scanning (that is, the ninth and tenth main scanning in this embodiment). However, the uppermost color dot in the third main scan and the fourth main scan cannot be formed in the ninth and tenth main scans after the second sub-scan. Therefore, it is formed at the time of original main scanning (at the time of the third and fourth main scanning). By performing the edge processing by such a method, it is possible to start printing by inserting the print medium deeply into the print head 241 while suppressing the formation of color dots as much as possible. .

H. Variations:
As mentioned above, although the various Example of this invention was described, it cannot be overemphasized that this invention is not limited to these Examples, and can take a various structure in the range which does not deviate from the meaning. For example, the following modifications are possible.

(H1) Modification 1:
In the first embodiment described above, as shown in FIG. 7, the filling order is set so that the 2 × 2 local region is filled in the order of upper left, lower left, upper right, and lower right. On the other hand, in the second embodiment, the filling order is set so that the 2 × 2 local region is filled in the order of upper left, lower right, upper right, and lower left. The number of metallic nozzles, number of color nozzles, number of overlaps, nozzle pitch, paper feed amount, and bidirectional printing conditions are the same as in the first embodiment.

  FIG. 24 shows the printing result according to this example. If the filling order is set as described above, as can be seen by comparing FIG. 7B and FIG. 24B, in this embodiment, the period in which dots are formed in even rows is the first implementation. Compared to the example, it is shifted by one dot in the horizontal direction. Therefore, finally, as shown in FIG. 24C, a pattern different from the pattern shown in FIG. 7C is formed on the print medium. Also in the present embodiment, by forming the special dither mask D2 based on the pattern shown in FIG. 24C, each nozzle of the print head 241 is moved to the preceding nozzle group and the following as in the first embodiment. It is possible to perform printing separately from nozzle groups.

(H2) Modification 2:
In the first embodiment described above, the preceding nozzle group and the succeeding nozzle group were each equally divided into seven for printing. On the other hand, in this modification, printing is performed with the number of preceding nozzle groups and the number of succeeding nozzle groups being divided unevenly. Specifically, four nozzles are included in the preceding nozzle group, and ten nozzles are included in the subsequent nozzle group. The printing conditions for the number of overlaps, nozzle pitch, paper feed amount, and bidirectional printing are the same as in the first embodiment.

  FIG. 25 shows a printing result according to this modification. FIG. 25A shows a state in which the nozzles in which the preceding nozzle group and the succeeding nozzle group are divided unevenly move in the sub-scanning direction. FIG. 25B and FIG. The dot generation patterns with different filling orders are shown. Also in this embodiment, by forming the special dither mask D2 based on the patterns shown in FIG. 25B and FIG. 25C, the number of leading nozzle groups and the number of succeeding nozzle groups are not equal. This makes it possible to perform printing. As can be seen from FIG. 17, in this embodiment, the number of main scans of the print head 241 for filling a predetermined local area in the special glossy area A1 with metallic ink is because the same local area is filled with color ink. This is less than the number of main scans of the print head 241.

  By the way, in this modification, the number of preceding nozzle groups that eject metallic ink is smaller than the number of succeeding nozzle groups, but it is of course possible to increase the number of preceding nozzle groups.

(H3) Modification 3:
In the above-described embodiment, the filling order is set in a local area having a size of 2 × 2. On the other hand, in this modified example, the filling order is set in a local area of 2 × 4 size.

  FIG. 26 shows a part of the printing result according to this modification. FIG. 26 (a) and FIG. 26 (b) show printing results with different filling orders. In this modification, bi-directional printing is performed with 7 nozzles included in the preceding nozzle group and the succeeding nozzle group, 2 overlap numbers, 4 nozzle pitches, and 7 paper feed amounts. As shown in FIG. 26, even if the filling order is set to a size of 2 × 4, a predetermined pattern is generated on the print medium. Also in this embodiment, the special dither mask D2 is formed based on the patterns shown in FIG. 26A and FIG. 26B, so that each nozzle of the print head 241 is replaced with the preceding nozzle group and the succeeding nozzle group. It is possible to print separately.

(H4) Modification 4:
In the third modified example, the filling order is set in the local region of 2 × 4 size. On the other hand, in this modified example, the filling order is set for a local region having a size of 4 × 2.

  FIG. 27 shows a printing result according to this modification. FIG. 27A, FIG. 27B, and FIG. 27C show printing results in different filling orders. In this modification, 28 nozzles are included in the nozzle row, and 14 nozzles are included in both the preceding nozzle group and the succeeding nozzle group. In addition, the number of overlaps is 4, the nozzle pitch is 2, the paper feed amount is 7, and bidirectional printing is performed. As shown in FIG. 27, even when the filling order is set to a size of 4 × 2, a predetermined pattern is generated on each print medium. Also in this embodiment, the special dither mask D2 is formed based on the patterns shown in FIGS. 27A, 27B, and 27C, so that each nozzle of the print head 241 is replaced with the preceding nozzle. It is possible to perform printing separately in groups and subsequent nozzle groups.

  In order to improve the dispersibility of dots formed on the print medium, the pattern formed on the print medium is as small as possible in the form of the band, and the metallic dots and color dots are evenly distributed. A pattern in which dots are not formed as continuously as possible at adjacent pixel positions is preferable. From this point of view, looking at the three types of patterns shown in FIG. 27, FIG. 27B shows a large pattern change, and FIG. 27C shows vertical stripes caused by two consecutive dots. Therefore, it can be considered that the pattern shown in FIG. 27A is the most advantageous pattern in terms of image quality.

(H5) Modification 5:
In the first embodiment described above, an example is shown in which the nozzle moves in the sub-scanning direction with an equally spaced paper feed amount. On the other hand, in this modification, an example in which the paper feed amount is changed for each main scan is shown.

  FIG. 28 shows a printing result according to this modification. In this modification, 14 nozzles are included in the nozzle row, and the number of nozzles included in the preceding nozzle group and the succeeding nozzle group is seven. In addition, the number of overlaps is 2, the nozzle pitch is 2, and bidirectional printing is performed. FIG. 28A shows how the nozzles move at unequal intervals in the sub-scanning direction. As shown in the figure, in this modification, the paper feed amount changes in order of “7”, “6”, “7”, “8” for each main scan. FIG. 28B and FIG. 28C show the printing results by such nozzle control. In these drawings, printing results in different filling orders are shown. As shown in FIG. 28, even if the paper feed amount changes at unequal intervals, a predetermined pattern is generated on each print medium. Also in this embodiment, the special dither mask D2 is formed based on the patterns shown in FIG. 28B and FIG. 28C, so that each nozzle of the print head 241 is replaced with the preceding nozzle group and the succeeding nozzle group. It is possible to print separately.

(H6) Modification 6:
In the embodiment described above, a special dither mask (special dither mask D2) is used during halftone processing by the systematic dither method, whereby the nozzle rows of the print head 241 are separated into the preceding nozzle group and the subsequent nozzle group. Printing. On the other hand, the nozzle row can be separated into the preceding nozzle group and the succeeding nozzle group also by the halftone process using the error diffusion method.

Specifically, assuming that the gradation data of each pixel takes a value from 0 to 255, in the normal error diffusion method,
(1) The error distributed from the processed pixel is added to the gradation data of the target pixel.
(2) The gradation data after the error addition is compared with a predetermined threshold value (= 127) and binarized.
(3) Error calculation between the binarized value (0 or 255) and the original gradation data.
(4) Distribute errors to surrounding unprocessed pixels at a predetermined ratio.
(5) Move the processing target to the next pixel.
Halftone processing is performed by the procedure. In the present modification, halftone processing is performed for the color single region A1 in such a procedure.

  On the other hand, in the special glossy area A2, prior to the procedure (2), it is determined whether the number of the nozzle that forms dots for the pixel of interest is 7 or less (that is, the subsequent nozzle group). In the case of No. 7 or less, processing for changing the threshold value to an extremely high value (for example, 1000) is added. Then, the probability of forming dots with the 1st to 7th nozzles becomes extremely small. As a result, the metallic ink can be preferentially printed by the preceding nozzle groups Nos. 8-14.

(H7) Modification 7:
In the embodiment described above, printing is performed in the printing system 10 constituted by the computer 100 and the printer 200. On the other hand, the printer 200 itself may perform printing by inputting image data from a digital camera or various memory cards. That is, the CPU in the control circuit 260 of the printer 200 may perform printing by executing processing equivalent to the above-described printing processing and halftone processing.

(H8) Modification 8:
In the embodiment described above, it is assumed that white printing paper is used as the printing medium. Therefore, the color ink is printed after the metallic ink is printed first. On the other hand, assuming that a transparent film is used as a printing medium and the film is viewed from the opposite side of the printing surface, it is preferable to print the color ink prior to printing the metallic ink. In this case, the special dither mask D2a for color ink shown in FIG. 8 may be used for metallic, and the special dither mask D2b for metallic ink shown in FIG. 11 may be used for color. In this case, the preceding nozzle group is configured by nozzles that eject color ink, and the subsequent nozzle group is configured by nozzles that eject metallic ink.

(H9) Modification 9:
In the embodiment described above, printing is performed using metallic ink and color ink. On the other hand, instead of metallic ink, white ink or transparent ink may be used. When the transparent ink is used for the purpose of protecting the printing surface or polishing, the transparent ink needs to be printed after the color ink is printed first. In this case, the threshold is arranged in the special dither mask D2 so that the preceding nozzle group is configured by nozzles that discharge color ink and the subsequent nozzle group is configured by nozzles that discharge transparent ink. Specifically, the special dither mask D2a for color ink shown in FIG. 8 may be diverted for transparent ink, and the special dither mask D2b for metallic ink shown in FIG. 11 may be diverted for color ink.

(H10) Modification 10:
In the embodiment described above, as shown in FIG. 6B, the positions of the preceding nozzle group and the succeeding nozzle group are completely separated from each other in the sub-scanning direction. On the other hand, as shown in FIG. 29, the positions of the preceding nozzle group and the succeeding nozzle group in the sub-scanning direction may partially overlap. Moreover, as shown in FIG. 30, an unused nozzle may be interposed between the preceding nozzle group and the succeeding nozzle group. In the above-described embodiment, the position in the sub-scanning direction of each nozzle that ejects metallic ink and the position in the sub-scanning direction of each nozzle that ejects color ink all coincide. On the other hand, as shown in FIG. 31, the positions in the sub-scanning direction may be shifted between the nozzles that discharge the metallic ink and the nozzles that discharge the color ink. Even when the nozzles are arranged as shown in FIGS. 29 to 31, the special dither mask is generated according to the principle shown in the above-described embodiment, so that the nozzles used when printing the special glossy area A2 can be preceded. Printing can be performed separately for the nozzle group and the succeeding nozzle group.

    DESCRIPTION OF SYMBOLS 10 ... Printing system 20 ... Application program 22 ... Video driver 24 ... Printer driver 40 ... Image acquisition module 42 ... Color conversion module 44 ... Halftone module 45 ... Area discrimination module 46 ... Print data output module 100 ... Computer 102 ... CPU 104 ... ROM 106 ... RAM 108 ... Peripheral device interface 109 ... Disk controller 110 ... Network interface card 112 ... Video interface 114 ... Display 116 ... Bus 118 ... Hard disk 120 ... Digital camera 122 ... Color scanner 200 ... Printer 230 ... Carriage motor 231 ... Drive belt 232 ... Pulley 233 ... Sliding shaft 234 ... Position detection sensor 235 ... Paper feed motor 236 ... Platen 240 ... Carriage 241 ... Print head 242 ... Metallic ink cartridge 243 ... Color ink cartridge 256 ... Operation panel 260 ... Control circuit 262 ... End processing module 300 ... Communication line 310: Storage device.

SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms or application examples.
A first aspect of the present invention is a printing apparatus that performs printing by moving a print head relative to a print medium in a main scanning direction and a sub-scanning direction that intersects the main scanning direction.
The first nozzle row in which a plurality of first nozzles capable of ejecting first ink are arranged, and the second nozzle row in which a plurality of second nozzles capable of ejecting second ink are arranged, Print heads arranged side by side in the main scanning direction;
A first nozzle group comprising first nozzles that are actually used in the first nozzle row is arranged on one side in the sub-scanning direction, and a second nozzle that is actually used in the second nozzle row. A second nozzle group of nozzles is arranged on the other side of the sub-scanning direction opposite to the one direction, and the first ink and the second ink are ejected from the print head to perform the printing. A dot forming section for forming dots on the medium,
The dot forming unit reduces a relative movement amount of the print head in the sub-scanning direction with respect to the print medium in a region other than the upper end region when forming dots on the upper end region of the print medium. And the first nozzle group before the number of the second nozzles constituting the second nozzle group is increased and the number of the second nozzles constituting the second nozzle group is increased. In the printing apparatus, the first nozzle constituting the first nozzle group is changed so as to include at least a part of the first nozzle that does not constitute the first nozzle group.
According to such a printing apparatus, it is possible to promote drying of the first ink and the second ink that are ejected first, so that the color development of the ink is prevented from being deteriorated. can do. Furthermore, in the printing apparatus, when forming dots in the upper end region, the number of second nozzles constituting the second nozzle group is increased, and the number of second nozzles constituting the second nozzle group is increased. Since the first nozzles constituting the first nozzle group are changed so as to include at least a part of the first nozzles that did not constitute the first nozzle group before the printing, when printing on the upper end region of the print medium There is no need to greatly move the print head in the sub-scanning direction. Therefore, dots can be formed at accurate positions.

Claims (9)

A printing apparatus that performs printing by driving a print head relative to a print medium in a main scanning direction that is a width direction of the printing medium and a sub-scanning direction that intersects the main scanning direction,
The first nozzle row in which a plurality of first nozzles capable of ejecting first ink are arranged, and the second nozzle row in which a plurality of second nozzles capable of ejecting second ink are arranged, A print head arranged to face along the sub-scanning direction;
The first nozzle group consisting of the first nozzle actually used in the first nozzle row is set to be more than the second nozzle group consisting of the second nozzle actually used in the second nozzle row. The first ink is disposed in advance in the sub-scanning direction, and the first ink is ejected to the same printing position in advance of the second ink while the print head is main-scanned and sub-scanned. A dot forming section for forming dots on the medium,
The dot forming unit reduces the sub-scanning amount of the print head from the sub-scanning amount in a region other than the end region when forming dots for the end region in the main scanning direction of the print medium, In order to compensate for the reduced sub-scanning amount, the arrangement and nozzle configuration of the first nozzle group in the first nozzle array, and the arrangement and nozzle arrangement of the second nozzle group in the second nozzle array, and A printing apparatus that performs end processing for changing a nozzle configuration for each main scan of the print head. The printing apparatus according to claim 1,
The dot forming unit maintains the front-rear relationship between the first nozzle group and the second nozzle group when forming dots on the end region along the main scanning direction of the print medium. Do printing device. The printing apparatus according to claim 2,
The dot forming unit is configured such that a boundary between the first nozzle group and the second nozzle group is located at an extreme end side of the end region in the first nozzle row and the second nozzle row. The printing apparatus compensates for the reduced sub-scanning amount by moving toward the opposite side of the endmost side. The printing apparatus according to any one of claims 1 to 3,
The dot forming unit is a printing apparatus that moves the print head in the sub-scanning direction in advance of the formation of the dots by the total amount of sub-scanning that is reduced during the edge processing. The printing apparatus according to any one of claims 1 to 4,
The printing apparatus, wherein the first ink is a special glossy ink whose optical characteristics after being printed on the surface of the printing medium have a reflection angle dependency. A printing apparatus according to any one of claims 1 to 5,
The printing apparatus, wherein the first ink is an ink containing a pigment that develops a metallic feeling. A printing method for performing printing by relatively driving a print head in a main scanning direction which is a width direction of a print medium and a sub-scanning direction intersecting the main scanning direction,
The print head includes a first nozzle row in which a plurality of first nozzles capable of ejecting a first ink are arranged, and a second nozzle in which a plurality of second nozzles capable of ejecting a second ink are arranged. A nozzle row is arranged facing the sub-scanning direction,
The first nozzle group consisting of the first nozzle actually used in the first nozzle row is set to be more than the second nozzle group consisting of the second nozzle actually used in the second nozzle row. The first ink is disposed in advance in the sub-scanning direction, and the first ink is ejected to the same printing position in advance of the second ink while the print head is main-scanned and sub-scanned. Forming dots on the medium,
When forming dots on the end region along the main scanning direction of the print medium, the sub-scanning amount of the print head is reduced more than the sub-scanning amount in the region other than the end region, and the reduced sub-scanning amount The arrangement of the first nozzle group and the nozzle configuration in the first nozzle row, and the arrangement and nozzle configuration of the second nozzle group in the second nozzle row so as to compensate for A printing method that changes with each main scan of the head. A computer program for performing printing by driving a print head relative to a main scanning direction which is a width direction of a print medium and a sub-scanning direction intersecting the main scanning direction,
The print head includes a first nozzle row in which a plurality of first nozzles capable of ejecting a first ink are arranged, and a second nozzle in which a plurality of second nozzles capable of ejecting a second ink are arranged. A nozzle row is arranged facing the sub-scanning direction,
The first nozzle group consisting of the first nozzle actually used in the first nozzle row is set to be more than the second nozzle group consisting of the second nozzle actually used in the second nozzle row. The first ink is disposed in advance in the sub-scanning direction, and the first ink is ejected to the same printing position in advance of the second ink while the print head is main-scanned and sub-scanned. A function of forming dots on the medium;
When forming dots on the end region along the main scanning direction of the print medium, the sub-scan amount of the print head is reduced from the sub-scan amount in the region other than the end region, and the sub-scan amount is reduced. The arrangement of the first nozzle group and the nozzle configuration in the first nozzle row, and the arrangement and nozzle configuration of the second nozzle group in the second nozzle row so as to compensate for A computer program that allows a computer to implement the functions that change each time the head scans.   The computer-readable recording medium which recorded the computer program of Claim 8.

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