JP5445602B2 - Printing apparatus, printing method, and printing program - Google Patents

Description

  The present invention relates to a technique for performing printing by forming dots on a print medium using a print head.

  2. Description of the Related Art In recent years, color printers that eject several colors of ink from a print head have become widespread as computer output devices, and are widely used on a daily basis. In addition, there is a demand for printing with high image quality on the surface of a synthetic resin data recording medium such as a compact disk using such a color printer.

  However, since the surface layer of the data recording medium made of synthetic resin has little ink absorption, there is a problem that when printing, the ink tends to aggregate on the surface of the printing medium, and the print image quality tends to deteriorate.

  SUMMARY An advantage of some aspects of the invention is to provide a technique for printing a high-quality image on a synthetic resin data recording medium.

In order to solve at least a part of the above-described problems, the present invention provides a print control apparatus that generates print data to be supplied to a printing unit that forms ink dots on a print medium,
A user interface unit that displays on the display unit a selection screen that allows the user to select one of a plurality of types of print media registered in advance, and that receives the selection by the user;
Print data for selecting one print mode according to the selected print medium from a plurality of preset print modes and generating print data for executing printing according to the selected print mode A generator,
With
When the selected print medium means a surface layer of a data recording medium made of synthetic resin, the print data generation unit specifies the slowest print speed among the plurality of print modes as at least an initial setting. The printing mode is selected.

  In the present invention, when the selected printing medium means a surface layer of a data recording medium made of synthetic resin, a specific printing mode having the slowest printing speed among the plurality of printing modes is set as at least an initial setting. Since the selection is made, the aggregation of ink droplets on the surface of the synthetic resin is suppressed, and the print image quality is improved.

In the print control apparatus,
The specific print mode is preferably a print mode having the largest number of main scans performed on each main scan line.

  In this case, since the time interval between a pass for forming a dot in a certain pixel and a pass for forming a dot in a pixel adjacent to the pixel tends to be long, aggregation of ink droplets is suppressed.

In the print control apparatus,
The specific print mode is preferably a print mode having the highest print resolution among the plurality of print modes.

  In general, when the printing resolution is high, the ink droplets are small, so that the ink solvent is easily evaporated, and aggregation of the ink droplets can be suppressed.

In the print control apparatus,
The specific printing mode is preferably a unidirectional printing mode.

  Since the unidirectional printing mode has a slower printing speed than the bidirectional printing mode, the aggregation of ink droplets can be further suppressed.

In the print control apparatus,
The specific print mode is a mode in which the limit value of the total ink amount per unit area is the smallest among the plurality of print modes.

  If the limit value of the total amount of ink per unit area is minimized, the maximum value of the total amount of ink ejected per unit area is minimized, so that aggregation of ink droplets can be suppressed.

In the print control apparatus,
The printing unit can execute printing using a plurality of same hue inks having substantially the same hue and different densities for at least one hue,
When the selected print medium means a surface layer of a data recording medium made of synthetic resin, the print data generation unit may use the plurality of the same hues for the hues that can be used with the plurality of the same hue inks. The print data is generated so that only the ink with a relatively high density is used without using the ink with the lowest density among the inks.

  In this way, the amount of ink is reduced as compared with the case of using the ink with the lowest density, so that the aggregation of ink droplets can be further suppressed.

In the above printing apparatus,
The print data generation unit preferably generates the print data so that dots of pixels adjacent in the main scanning direction are not formed by continuous main scanning but are formed by non-continuous main scanning.

  In this way, when dots are formed in a certain pixel, the ink droplets of the dots formed in advance in the pixels adjacent in the main scanning direction are considerably dried, and thus aggregation of the ink droplets is suppressed.

In the above printing apparatus,
The print data generation unit preferably generates the print data so that dots of pixels adjacent in the sub-scanning direction are not formed by continuous main scanning but are formed by non-continuous main scanning.

  In this way, when forming dots on a certain pixel, aggregation of ink droplets in the sub-scanning direction is also suppressed.

In the above printing apparatus,
The print data generation unit generates print data so that dots of pixels adjacent in an oblique direction between the main scanning direction and the sub-scanning direction are not formed by continuous main scanning but by non-continuous main scanning. Preferably it is produced.

  By doing so, aggregation of ink droplets of pixels adjacent to each other in an oblique direction between the main scanning direction and the sub-scanning direction is also suppressed.

  The print control device that generates print data as described above may be realized by a computer configured as a device separate from the printing device including the printing unit, or may be realized by a circuit in the printing device. .

  The present invention can be realized in various modes. For example, a printing method and a printing apparatus, a printing control method and a printing control apparatus, a computer program for realizing the functions of these methods or apparatuses, and the like The present invention can be realized in the form of a recording medium that records a computer program, a data signal that includes the computer program and is embodied in a carrier wave, and the like.

1 is a block diagram showing the configuration of a printing system as an embodiment of the present invention. FIG. 3 is an explanatory diagram showing a printing condition setting window displayed on the display unit 21 of the computer 90. FIG. 4 is an explanatory diagram showing the contents of a plurality of print mode tables 104 registered in a printer driver 96. FIG. 3 is an explanatory diagram illustrating a configuration of a printer. FIG. 2 is a block diagram illustrating a configuration of a control circuit 40 in the color printer 20. FIG. 3 is an explanatory diagram showing a nozzle arrangement on the lower surface of the print head. FIG. 3 is a block diagram showing the main configuration of a head drive circuit 52. 5 is a timing chart showing the operation of the head drive circuit 52. Explanatory drawing for showing basic conditions of a normal interlace recording method. Explanatory drawing for showing the basic conditions of the overlap recording method. Explanatory drawing which shows the generation | occurrence | production of aggregation and the condition of the suppression. Explanatory drawing which shows the dot recording system of the 1st example of the dot recording system of this invention. Explanatory drawing which shows the 2nd example of the dot recording system of this invention. Explanatory drawing which shows the dot recording position of each pass in the 1st example of the dot recording system of this invention, and a 2nd example. Explanatory drawing which shows the dot recording system of the 3rd example of the dot recording system of this invention. Explanatory drawing which shows the dot recording position of each pass in the 2nd example of the dot recording system of this invention, and a 3rd example. Explanatory drawing which shows the 4th example of the dot recording system of this invention. Explanatory drawing which shows the dot recording position of each pass in the 2nd example of the dot recording system of this invention, and a 4th example. The figure which shows the relationship between an ink duty and the recording rate of each ink.

Next, embodiments of the present invention will be described in the following order based on examples.
A. Summary of Examples:
B. Device configuration:
C. Basic conditions of recording method:
D. Preventing aggregation by selecting the print mode:
E. Preventing aggregation by changing the recording method:
F. Variations:

A. Summary of Examples:
FIG. 1 is a block diagram showing the configuration of a printing system as an embodiment of the present invention. This printing system includes a computer 90 as a printing control device and a color printer 20 as a printing unit. The combination of the color printer 20 and the computer 90 can be called a “printing apparatus” in a broad sense.

  In the computer 90, an application program 95 operates under a predetermined operating system. A video driver 91 and a printer driver 96 are incorporated in the operating system, and print data PD to be transferred to the color printer 20 is output from the application program 95 via these drivers. The application program 95 performs desired processing on the image to be processed, and displays an image on the display unit 21 via the video driver 91.

  When the application program 95 issues a print command, the printer driver 96 of the computer 90 receives image data from the application program 95 and converts it into print data PD to be supplied to the color printer 20. In the example shown in FIG. 1, the printer driver 96 includes a resolution conversion module 97, a color conversion module 98, a halftone module 99, a rasterizer 100, and a color conversion table LUT.

  The resolution conversion module 97 plays a role of converting the resolution of the color image data handled by the application program 95 (that is, the number of pixels per unit length) into a resolution that can be handled by the printer driver 96. The image data subjected to resolution conversion in this way is still image information composed of three colors of RGB. The color conversion module 98 converts RGB image data into multi-tone data of a plurality of ink colors that can be used by the color printer 20 for each pixel while referring to the color conversion table LUT.

  The color-converted multi-gradation data has, for example, 256 gradation values. The halftone module 99 executes halftone processing for expressing the gradation value by the color printer 20 by forming the ink dots in a dispersed manner. The halftone processed image data is rearranged in the order of data to be transferred to the color printer 20 by the rasterizer 100 and output as final print data PD. The print data PD includes raster data indicating the dot recording state during each main scan and data indicating the sub-scan feed amount.

  The printer driver 96 corresponds to a program for realizing a function for generating the print data PD. A program for realizing the function of the printer driver 96 is supplied in a form recorded on a computer-readable recording medium. Such recording media include flexible disks, CD-ROMs, magneto-optical disks, IC cards, ROM cartridges, punch cards, printed matter on which codes such as bar codes are printed, computer internal storage devices (such as RAM and ROM). A variety of computer-readable media such as a memory) and an external storage device can be used.

  FIG. 2 is an explanatory diagram showing a print condition setting window displayed on the display unit 21 of the computer 90 by the user interface unit 102 of the printer driver 96. The user can select the type of printing medium (also referred to as “printing paper”), the selection of whether or not to use color ink, and the printing mode setting as basic settings for printing conditions.

  In addition to CD-R (“synthetic resin data recording medium”), a plurality of types of media such as plain paper, photo print paper, and OHP sheet are registered in advance as print media. The user can select a medium to be used for printing from the plurality of types of print media.

  As the mode setting, one of three settings, a recommended setting (initial setting), an auto photo fine setting, and a detailed setting can be selected. In the “recommended setting”, when the user selects one print medium, a print mode suitable for the type of the print medium is automatically set. In “Auto Photo Fine Setting”, various conditions for printing a photographic image with high image quality are automatically set. In the “detailed setting”, the user can arbitrarily select various conditions.

  FIG. 3 is an explanatory diagram showing the contents of a plurality of print mode tables 104 registered in the printer driver 96. This print mode table includes a total of 16 print modes from mode 1a to mode 4d. Four printing resolutions of 360 × 360 dpi, 360 × 720 dpi, 720 × 720 dpi, and 1440 × 720 dpi can be used. Here, each print resolution is represented by (resolution in the main scanning direction) × (resolution in the sub-scanning direction). The “maximum ink weight” shown in the table of FIG. 3 means the weight of the largest ink dot among a plurality of types of ink dots that can be used at each resolution. In general, the higher the printing resolution, the smaller the ink weight. Therefore, the higher the printing resolution, the easier the individual ink dots dry.

  For one print resolution, four print modes are provided according to the print direction (unidirectional or bidirectional) and the number of inks used (six colors or four colors), respectively. When the number of inks used is four, four types of CMYK inks are used. When the number of inks is six, light cyan ink and light magenta ink are used in addition to the four types of CMYK inks.

  By the way, the printing speed is generally faster as the number of scan repetitions (described later) is smaller and the printing resolution is lower, and bidirectional printing is faster than unidirectional printing. Therefore, among the 16 types of print modes in FIG. 3, the 360 × 360 dpi bidirectional printing modes 1a and 1b with the smallest number of scan repetitions have the fastest printing speed and the 1440 × 720 dpi unidirectional printing with the largest number of scan repetitions. Modes 4c and 4d have the slowest printing speed. In general, as the printing speed is slower, the individual ink dots are more likely to be dried, and thus the inks tend not to aggregate.

  The right half of FIG. 3 shows the relationship between the type of print medium and selectable print modes. Modes marked with ◎ are modes selected according to the print medium in the recommended settings (FIG. 2), and modes marked with ◯ are modes that can be selected by the user in the detailed settings. For example, when plain paper is selected as the print medium, the recommended setting is mode 1b (360 × 360 dpi, bidirectional printing, four-color printing). In the case of plain paper, the user cannot select the four modes 2a to 2d of 360 × 720 dpi. On the other hand, when CD-R is selected as the print medium, the recommended setting is mode 4d (1440 × 720 dpi, unidirectional printing, four-color printing). In the case of CD-R, the user cannot select a mode other than the two modes 4c and 4d with the slowest printing speed. Thus, in the recommended setting (initial setting) of the print mode, one print mode is selected in advance according to the type of print medium (more specifically, the material of the print medium).

  The “maximum ink amount” in the column of each print medium means a limit value of the total amount of all ink amounts per unit area. In FIG. 3, various printing modes are classified based on only three parameters: printing resolution, printing direction, and number of inks used. Therefore, even in the same print mode, other parameters such as the maximum ink amount may differ depending on the print medium. Specifically, the maximum ink amount in the printing mode 4d is 11.9 mg / inch @ 2 for plain paper, 16.7 mg / inch @ 2 for photo print paper, and 7.2 mg / inch @ 2 for CD-R. That is, when printing on a CD-R, the limit value of the maximum ink amount is set lower than when printing on other print media. That is, in the CD-R printing, the total amount of ink per unit area is smaller than the printing of other printing media, so that the ink is more easily dried and the inks are less likely to aggregate.

  In this embodiment, the print mode is classified based on only three parameters of the print resolution, the print direction, and the number of used inks. However, using other parameters (for example, the maximum ink amount), The print mode may be subdivided.

  As described above, in this embodiment, when the CD-R is printed, the mode 4d having the slowest printing speed among the printing modes 1a to 4d available in the printer 20 is selected as the recommended setting, so that the ink is dried. It becomes easy and the aggregation of ink can be relieved. Since the printing mode 4d is the mode with the highest printing resolution, there is an advantage that the weight of the ink droplet is small and the ink is easy to dry. Further, in this printing mode 4d, since the limit value of the total ink amount per unit area is the lowest, also in this respect, the ink is easily dried and the inks are less likely to aggregate.

  In the printing mode 4d, only relatively high density ink is used as cyan and magenta, and light ink is not used. Therefore, the amount of ink can be reduced as compared with the case where light ink is used. This facilitates the drying of the ink and enhances the effect that the inks hardly aggregate.

  In the present embodiment, as a recommended setting print mode at the time of CD-R printing, the print resolution is the highest, unidirectional printing is performed, light ink is not used, and the maximum ink amount is the smallest. 4d is selected. However, it is also possible to select a print mode that does not have at least some of these features as a recommended setting for the CD-R.

B. Device configuration:
FIG. 4 is a schematic configuration diagram of the color printer 20. The color printer 20 includes a sub-scan feed mechanism that transports the printing paper P in the sub-scan direction by the paper feed motor 22 and a main scan feed that reciprocates the carriage 30 in the axial direction (main scan direction) of the platen 26 by the carriage motor 24. Mechanism, a head drive mechanism that drives a print head unit 60 (also referred to as a “print head assembly”) mounted on the carriage 30 to control ink ejection and dot formation, and these paper feed motor 22, carriage motor 24, a control circuit 40 that controls the exchange of signals with the print head unit 60 and the operation panel 32. The control circuit 40 is connected to the computer 90 via the connector 56.

  The sub-scan feed mechanism for transporting the printing paper P includes a gear train (not shown) that transmits the rotation of the paper feed motor 22 to the platen 26 and a paper transport roller (not shown). Further, the main scanning feed mechanism for reciprocating the carriage 30 has an endless drive belt 36 between the carriage motor 24 and a slide shaft 34 that is installed in parallel with the axis of the platen 26 and slidably holds the carriage 30. And a position sensor 39 for detecting the origin position of the carriage 30.

  FIG. 5 is a block diagram showing the configuration of the color printer 20 with the control circuit 40 as the center. The control circuit 40 is configured as an arithmetic and logic circuit including a CPU 41, a programmable ROM (PROM) 43, a RAM 44, and a character generator (CG) 45 that stores a dot matrix of characters. The control circuit 40 further includes an I / F dedicated circuit 50 dedicated to interface with an external motor and the like, and a head that is connected to the I / F dedicated circuit 50 and drives the print head unit 60 to eject ink. A drive circuit 52, a motor drive circuit 54 that drives the paper feed motor 22 and the carriage motor 24, and a scanner control circuit 55 that controls the scanner 80 are provided. The I / F dedicated circuit 50 incorporates a parallel interface circuit and can receive print data PD supplied from the computer 90 via the connector 56. The color printer 20 executes printing according to the print data PD. The RAM 44 functions as a buffer memory for temporarily storing raster data.

  The print head unit 60 has a print head 28 and can be mounted with an ink cartridge. The print head unit 60 is attached to and detached from the color printer 20 as one component. That is, when the print head 28 is to be replaced, the print head unit 60 is replaced.

  FIG. 6 is an explanatory diagram showing the nozzle arrangement on the lower surface of the print head 28. On the lower surface of the print head 28, a black ink nozzle group KD for discharging black ink, a dark cyan ink nozzle group CD for discharging dark cyan ink, and a light cyan ink nozzle for discharging light cyan ink. A group CL, a dark magenta ink nozzle group MD for ejecting dark magenta ink, a light magenta ink nozzle group ML for ejecting light magenta ink, and a yellow ink nozzle group YD for ejecting yellow ink. Is formed.

  The capital letter of the first alphabet in the code indicating each nozzle group means the ink color, and the subscript “D” indicates that the ink has a relatively high density, and the subscript “L” This means that the ink has a relatively low density.

  The plurality of nozzles of each nozzle group are aligned at a constant nozzle pitch k · D along the sub-scanning direction SS. Here, k is an integer, and D is a pitch (referred to as “dot pitch”) corresponding to the printing resolution in the sub-scanning direction. In this specification, it is also referred to as “nozzle pitch is k dots”. The unit [dot] at this time means the dot pitch of the printing resolution. Similarly, the unit of [dot] is used for the sub-scan feed amount.

  Each nozzle is provided with a piezo element (not shown) as a drive element for driving each nozzle to eject ink droplets. During printing, ink droplets are ejected from each nozzle while the print head 28 moves in the main scanning direction MS.

  The plurality of nozzles in each nozzle group need not be arranged in a straight line along the sub-scanning direction, and may be arranged in a staggered pattern, for example. Even when the nozzles are arranged in a staggered pattern, the nozzle pitch k · D measured in the sub-scanning direction can be defined as in the case of FIG. In this specification, the phrase “a plurality of nozzles arranged along the sub-scanning direction” has a broad meaning including nozzles arranged in a straight line and nozzles arranged in a staggered pattern. Yes.

  FIG. 7 is a block diagram showing the main configuration of the head drive circuit 52 (FIG. 5). FIG. 8 is a timing chart showing the operation of the head drive circuit 52. The head drive circuit 52 includes an original drive signal generator 220, a plurality of mask circuits 222, and a piezo element PE for each nozzle. The mask circuit 222 is provided corresponding to each nozzle # 1, # 2,. In FIGS. 7 and 8, the number in parentheses at the end of the signal name indicates the number of the nozzle to which the signal is supplied.

  The original drive signal generator 220 generates an original drive signal ODRV (FIG. 8A) used in common for each nozzle and supplies it to the plurality of mask circuits 222. The original drive signal ODRV is a signal including one pulse within the main scanning period Td for one pixel as shown in FIG. 8B, for example. The i-th mask circuit 222 masks the original drive signal ODRV according to the level of the serial print signal PRT (i) of the i-th nozzle. Specifically, when the print signal PRT (i) is 1 level, the mask circuit 222 passes the original drive signal ODRV as it is and supplies it as the drive signal DRV to the piezo element PE, while the print signal PRT (i) When the level is 0, the original drive signal ODRV is cut off. The serial print signal PRT (i) is a signal indicating the recording state of each pixel recorded by the i-th nozzle in one main scan, and print data PD (FIG. 4) given from the computer 90 is used for each nozzle. It has been disassembled. 8 is an example in which dots are recorded every other pixel. When dots are recorded in all pixels, the original drive signal ODRV is supplied as it is to the piezo element PE as the drive signal DRV. Is done.

  In the color printer 20 having the hardware configuration described above, the carriage 30 is reciprocated by the carriage motor 24 while the paper P is transported by the paper feed motor 22, and simultaneously the piezo elements of the print head 28 are driven, so that each color ink Droplets are ejected to form ink dots on the paper P to form a multicolor / multi-tone image.

C. Basic conditions of recording method:
Before describing the details of the recording system used in the embodiment of the present invention, first, the basic conditions of the normal interlace recording system will be described first. The “interlace recording method” refers to a recording method that is employed when the nozzle pitch k [dots] measured in the sub-scanning direction of the print head is 2 or more. In the interlaced recording method, a raster line that cannot be recorded remains between neighboring nozzles in one main scan, and pixels on this raster line are recorded during another main scan. In this specification, “printing method” and “recording method” are synonymous.

  FIG. 9 is an explanatory diagram for showing basic conditions of a normal interlace recording method. FIG. 9A shows an example of sub-scan feed when four nozzles are used, and FIG. 9B shows the parameters of the dot recording method. In FIG. 9A, solid circles including numbers indicate the positions in the sub-scanning direction of the four nozzles in each pass. Here, “pass” means one main scan. Numbers 0 to 3 in the circles indicate nozzle numbers. The positions of the four nozzles are sent in the sub-scanning direction every time one main scanning is completed. However, in practice, the feed in the sub-scanning direction is realized by moving the paper by the paper feed motor 22 (FIG. 4).

  As shown at the left end of FIG. 9A, in this example, the sub-scan feed amount L is a constant value of 4 dots. Accordingly, every time the sub-scan feed is performed, the positions of the four nozzles are shifted in the sub-scanning direction by 4 dots. Each nozzle targets all dot positions (also referred to as “pixel positions”) on each raster line during one main scan. In the present specification, the total number of main scans performed on each raster line (also referred to as “main scan line”) is referred to as “scan repetition number s”.

  At the right end of FIG. 9A, the number of the nozzle that records the dots on each raster line is shown. In a raster line drawn with a broken line extending in the right direction (main scanning direction) from a circle indicating the position of the nozzle in the sub-scanning direction, at least one of the upper and lower raster lines cannot be recorded. Is prohibited. On the other hand, a raster line drawn with a solid line extending in the main scanning direction is a range in which the raster lines before and after the raster line can be recorded as dots. The range in which recording can actually be performed in this way is hereinafter referred to as an effective recording range (or “effective printing range”, “print execution area”, and “record execution area”).

  FIG. 9B shows various parameters relating to this dot recording method. The parameters of the dot recording method include nozzle pitch k [dots], number of used nozzles N [pieces], number of scan repetitions s, number of effective nozzles Neff [pieces], and sub-scan feed amount L [dots]. include.

  In the example of FIG. 9, the nozzle pitch k is 3 dots. The number of used nozzles N is four. The number N of used nozzles is the number of nozzles actually used among the plurality of mounted nozzles. The scan repetition number s means that s main scans are executed on each raster line. For example, when the scan repetition number s is 2, two main scans are executed on each raster line. At this time, normally, dots are intermittently formed every other dot in one main scan. In the case of FIG. 9, the scan repetition number s is 1. The effective nozzle number Neff is a value obtained by dividing the used nozzle number N by the scan repetition number s. This effective nozzle number Neff can be considered to indicate the net number of raster lines in which dot recording is completed in one main scan.

  The table of FIG. 9B shows the sub-scan feed amount L, the cumulative value ΣL, and the nozzle offset F in each pass. Here, the offset F is the position of the nozzle in each subsequent pass, assuming that the periodic position of nozzles in the first pass 1 (positions every 4 dots in FIG. 9) is the reference position where the offset is 0. Is a value indicating how many dots are apart from the reference position in the sub-scanning direction. For example, as shown in FIG. 9A, after pass 1, the position of the nozzle moves in the sub-scanning direction by the sub-scan feed amount L (4 dots). On the other hand, the nozzle pitch k is 3 dots. Therefore, the nozzle offset F in pass 2 is 1 (see FIG. 9A). Similarly, the nozzle position in pass 3 has moved by ΣL = 8 dots from the initial position, and its offset F is 2. The nozzle position in pass 4 has moved by ΣL = 12 dots from the initial position, and its offset F is zero. In pass 4 after three sub-scan feeds, the nozzle offset F returns to 0. Therefore, by repeating this cycle with three sub-scans as one cycle, all the dots on the raster line in the effective recording range can be obtained. Can be recorded.

  As can be seen from the example of FIG. 9, when the position of the nozzle is away from the initial position by an integer multiple of the nozzle pitch k, the offset F is zero. The offset F is given by the remainder (ΣL)% k obtained by dividing the cumulative value ΣL of the sub-scan feed amount L by the nozzle pitch k. Here, “%” is an operator indicating that the remainder of division is taken. If the initial position of the nozzle is considered as a periodic position, the offset F can be considered to indicate a phase shift amount from the initial position of the nozzle.

  When the number of scan repetitions s is 1, the following conditions must be satisfied in order to prevent missing or overlapping raster lines to be recorded in the effective recording range.

  Condition c1: The number of sub-scan feeds in one cycle is equal to the nozzle pitch k.

  Condition c2: Nozzle offset F after each sub-scan feed in one cycle is a different value in the range of 0 to (k−1).

  Condition c3: The sub-scan average feed amount (ΣL / k) is equal to the number N of used nozzles. In other words, the cumulative value ΣL of the sub-scan feed amount L per cycle is equal to a value (N × k) obtained by multiplying the number of used nozzles N and the nozzle pitch k.

  Each of the above conditions can be understood by thinking as follows. Since there are (k−1) raster lines between neighboring nozzles, printing is performed on these (k−1) raster lines in one cycle, and the nozzle reference position (offset F is zero). In order to return to (position), the number of sub-scan feeds in one cycle is k times. If the number of sub-scan feeds in one cycle is less than k times, the recorded raster lines are missing. If the number of sub-scan feeds in one cycle is more than k times, the recorded raster lines are overlapped. Therefore, the first condition c1 is satisfied.

  When the number of sub-scan feeds in one cycle is k times, only when the offset F value after each sub-scan feed is a different value in the range of 0 to (k-1), the recorded raster lines are not missing. There will be no overlap. Therefore, the second condition c2 is satisfied.

  If the first and second conditions are satisfied, each of the N nozzles records k raster lines in one cycle. Therefore, N × k raster lines are recorded in one cycle. On the other hand, if the third condition c3 is satisfied, as shown in FIG. 9A, the nozzle position after one cycle (after k sub-scan feeds) is N × k from the initial nozzle position. Comes away from the raster line. Therefore, by satisfying the first to third conditions c1 to c3, it is possible to eliminate missing or overlapping raster lines to be recorded in the range of these N × k raster lines.

  FIG. 10 is an explanatory diagram for illustrating basic conditions of the dot recording method when the scan repetition number s is 2 or more. When the scan repetition number s is 2 or more, s main scans are executed on the same raster line. Hereinafter, a dot recording method in which the scan repetition number s is 2 or more is referred to as an “overlap method”.

  The dot recording method shown in FIG. 10 is obtained by changing the number of scan repetitions s and the sub-scan feed amount L among the parameters of the dot recording method shown in FIG. As can be seen from FIG. 10A, the sub-scan feed amount L in the dot recording method of FIG. 10 is a constant value of 2 dots. However, in FIG. 10A, the positions of the nozzles in the even-numbered passes are indicated by diamonds. Normally, as shown at the right end of FIG. 10A, the dot position recorded in the even-numbered pass is shifted from the dot position recorded in the odd-numbered pass by one dot in the main scanning direction. . Therefore, a plurality of dots on the same raster line are intermittently recorded by two different nozzles. For example, the uppermost raster line in the effective recording range is intermittently recorded every other dot by the second nozzle in pass 2, and then intermittently recorded every other dot by the zeroth nozzle in pass 5. Is done. In this overlap method, each nozzle is driven at an intermittent timing so that (s-1) dot recording is prohibited after recording one dot during one main scan.

  In this way, an overlap method in which intermittent pixel positions on the raster line are recorded during each main scan is called an “intermittent overlap method”. Instead of setting intermittent pixel positions as recording targets, all pixel positions on the raster line may be set as recording targets at the time of each main scanning. That is, when s main scans are executed on one raster line, dot overstrike may be allowed at the same pixel position. Such an overlap method is called “overlap overlap method” or “complete overlap method”.

  In the intermittent overlap method, it is only necessary that the positions in the main scanning direction of a plurality of nozzles that record the same raster line are shifted from each other. Therefore, the actual shift amount in the main scanning direction during each main scanning is shown in FIG. Various things other than those shown in A) are conceivable. For example, in pass 2, it is possible to record dots at positions indicated by circles without shifting in the main scanning direction, and to record dots at positions indicated by diamonds in pass 5 by shifting in the main scanning direction. It is.

  The value of the offset F of each path in one cycle is shown at the bottom of the table in FIG. One cycle includes six passes, and the offset F in each pass from pass 2 to pass 7 includes a value in the range of 0 to 2 twice. Further, the change in the offset F in the three passes from the pass 2 to the pass 4 is equal to the change in the offset F in the three passes from the pass 5 to the pass 7. As shown at the left end of FIG. 10A, the six passes of one cycle can be divided into two sets of three small cycles. At this time, one cycle is completed by repeating the small cycle s times.

  In general, when the scan repetition number s is an integer of 2 or more, the first to third conditions c1 to c3 described above are rewritten as the following conditions c1 'to c3'.

  Condition c1 ′: The number of sub-scan feeds in one cycle is equal to a value (k × s) obtained by multiplying the nozzle pitch k and the scan repetition number s.

  Condition c2 ': Nozzle offset F after each sub-scan feed in one cycle is a value in the range of 0 to (k-1), and each value is repeated s times.

  Condition c3 ′: The sub-scan average feed amount {ΣL / (k × s)} is equal to the effective nozzle number Neff (= N / s). In other words, the cumulative value ΣL of the sub-scan feed amount L per cycle is equal to a value {Neff × (k × s)} obtained by multiplying the effective nozzle number Neff and the sub-scan feed number (k × s).

  The above conditions c1 'to c3' are satisfied even when the scan repetition number s is 1. Therefore, the conditions c1 'to c3' are considered to be conditions that are generally satisfied for the interlace recording method regardless of the value of the scan repetition number s. That is, if the above three conditions c1 'to c3' are satisfied, it is possible to prevent missing dots and unnecessary overlap in the effective recording range. However, when the intermittent overlap method is adopted, it is also necessary to have a condition that the recording positions of the nozzles that record the same raster line are shifted in the main scanning direction. In addition, when the overlapped overlap method is adopted, it is sufficient that the above conditions c1 'to c3' are satisfied, and all pixel positions are recorded in each pass.

  9 and 10, the case where the sub-scan feed amount L is a constant value has been described. However, the above-described conditions c1 ′ to c3 ′ are not limited to the case where the sub-scan feed amount L is a constant value. The present invention is also applicable when using a combination of a plurality of different values as the sub-scan feed amount. In the present specification, sub-scan feed with a constant feed amount L is called “regular feed”, and sub-scan feed using a combination of a plurality of different values as feed amounts is called “regular feed”.

D. Preventing aggregation by selecting the print mode:
FIG. 11 is an explanatory diagram showing the occurrence of aggregation and the state of its suppression. FIG. 11A is a diagram illustrating a process in which aggregation occurs, and FIG. 11B is a diagram illustrating a case in which aggregation does not occur. (A-1) in FIG. 11A is a state in which the ink droplets ejected from the nozzles adhere to a certain position on the print medium. (A-2) shows a state when another ink droplet adheres to an adjacent pixel before the ink droplet is absorbed into the print medium or evaporated to become small. Here, the adjacent pixel means two or more pixels sharing at least one point or line. When adjacent to each other in the sub scanning direction, adjacent to the main scanning direction, and the main scanning direction and the sub scanning direction. May be adjacent to each other in an oblique direction. In this case, as shown in (a-3), the two ink droplets are combined to form a large ink droplet. Such a state in which the ink droplets are continuously combined is called ink aggregation, which causes deterioration in image quality. In particular, a print medium that does not absorb much ink, such as synthetic resin, is likely to agglomerate, which is a major cause of image quality degradation.

  A dotted line (b-1) in FIG. 11B shows a state in which the ink droplets ejected from the nozzles adhere to a certain position on the print medium. (B-2) shows a state when the ink droplets ejected earlier are absorbed by the print medium or evaporated to become small, and then the ink droplets ejected later adhere to adjacent pixels. As shown in (b-2), it can be seen that the ink droplets on the left side are smaller and are not combined with the ink droplets on the right side.

  In this way, if an ink drop adheres to a certain pixel and a sufficient time has passed, then if the ink drop is attached to an adjacent pixel, the combination of the two ink drops can be prevented, and aggregation can be suppressed. Become. For this purpose, for example, it is preferable to select a printing mode of unidirectional printing instead of bidirectional printing. In addition, when the printing resolution is increased, the ink droplets are reduced and drying is further promoted. For this purpose, it is preferable to select a printing mode with a higher resolution. As a result, it can be seen that it is preferable to automatically select a specific printing mode having a low printing speed in accordance with the printing medium.

  To automatically select according to the print medium, as described above, when a synthetic resin print medium is selected in the print condition setting window (FIG. 2), the print mode is automatically selected. It is only necessary that the selection range be narrowed. For example, in this example, when a synthetic resin print medium is selected as the print medium, it is possible to select only a specific print mode 4c or 4d having the slowest print speed in the print mode table 104 (FIG. 3). . However, for example, even in the next slowest printing mode 4a, 4b, if it is possible to print cleanly on a synthetic resin printing medium, it may be possible to select from specific printing modes 4a to 4d. In this case, when “recommended setting” is selected as the mode setting, it is preferable that the specific printing mode 4c or 4d that is late in the printing mode table 104 is automatically selected.

  As described above, in the present invention, when a synthetic resin data recording medium such as a compact disk is set as a printing medium, the printing mode with the slowest printing speed per unit area is automatically set. As a result, even when printing is performed on a synthetic resin that does not absorb much ink, deterioration in image quality due to aggregation can be suppressed and print image quality can be improved. In this printing mode, a more beautiful printing can be performed by adopting a dot recording method and a color conversion table LUT suitable for printing on a synthetic resin data recording medium.

E. Preventing aggregation by changing the recording method:
FIG. 12 is an explanatory diagram showing the dot recording method of the first example of the dot recording method of the present invention. The parameters of this recording method are N = 12, k = 4, L = 3, and s = 4. These parameters satisfy the above-mentioned conditions c1 ′ to c3 ′. Accordingly, printing can be executed without missing or unnecessary duplication of recorded dots. Further, as described in the basic conditions of the recording method, since the nozzle pitch k is 4 and the scan repetition number s is 4, one pass includes 16 passes. FIG. 12 shows a part of 16 passes included in one cycle.

  The pixel position number shown at the right end of FIG. 12 indicates the order of arrangement of the pixels on each raster line, and the number in the circle indicates the number of the path in charge of dot formation at that pixel position. For example, dots are formed on the first raster line by four passes of # 1, # 5, # 9, and # 13. That is, for the first raster line, a dot with pixel position number (1 + 4 × n) forms a # 1 pass, and a dot with pixel position number (2 + 4 × n) forms a # 5 pass. This indicates that the dot with the pixel position number (3 + 4 × n) forms the # 9 pass, and the dot with the pixel position number (4 + 4 × n) forms the # 13 pass. Similarly, the dots on the second raster line are formed by the passes of # 4, # 8, # 12, and # 16, and the dots on the third raster line are # 3, # 7, # 11, and # 15. The dots on the fourth raster line are formed by passes, and are formed by passes # 2, # 6, # 10, and # 14. In this way, the (1 + 3 × m) th raster line is a path of # 1, # 5, # 9, and # 13, and the (2 + 3 × m) th raster line is # 4, # 8, # 12, and # 13. In the 16th pass, the (3 + 3 × m) th raster line is the # 3, # 7, # 11 and # 15 pass, and the (4 + 3 × m) th raster line is the # 2, # 6 and # 10. It is formed by the # 14 pass. In this specification, m and n are non-negative integers.

  Such a raster line is formed by controlling the timing of the print signal PRT (i) (FIG. 8). Specifically, for example, in order to form dots in the # 1 pass at the pixel position number (1 + 4 × n) of the first raster line, the print signal PRT (i ) May be controlled so as to be output only at the (1 + 4 × n) th pixel position. That is, only when the (1 + 4 × n) th dot is recorded, the print signal PRT (i) is output. For the (2 + 4 × n), (3 + 4 × n), and (4 + 4 × n) th dots, the dot Regardless of whether or not is recorded, the print signal PRT (i) should not be output.

  For example, if the time required for dot formation between two pixels adjacent in the main scanning direction is 5 seconds, the raster number in the first example is 1 and the pixel position number is 1 It takes 20 seconds for a pixel and a pixel with a raster number of 1 and a pixel position number of 2. As described above, when the number of scan repetitions s is 2 or more, one raster line is formed by a plurality of passes. Therefore, dots of pixels adjacent in the main scanning direction are not formed by continuous main scanning. , It can be formed by discontinuous main scanning. As a result, the ink droplets of dots formed in advance on pixels adjacent in the main scanning direction are considerably dried, and aggregation of the ink droplets in the main scanning direction is suppressed.

  However, focusing on the pixel position with the pixel position number 1, the pixel with the raster number 5 has the # 1 pass, the pixel with the raster number 4 has the # 2 pass, and the pixel with the raster number 3 has the # 3 pass. The pass # 4 is assigned to the pixel whose raster number is 2 and the # 4 pass. In this way, consecutive passes such as # 1, # 2, # 3,... Are sequentially adjacent in the sub-scanning direction. The same applies to other pixel positions.

  FIG. 13 is an explanatory diagram showing a second example of the dot recording method of the present invention. This dot recording method has the same parameters as the recording method of the first example, but the pixel positions to be recorded in each pass are different from the dot recording method of the first example. Specifically, the (1 + 4 × m) th and (3 + 4 × m) th raster lines are the same as in the first example, but the (2 + 4 × m) th and (4 + 4 × m) adjacent to this are the same. The pixel position is different for the second raster line. For example, in the second example, a dot with a pixel position number (1 + 4 × n) forms a # 10 pass, and a dot with a pixel position number (2 + 4 × n) forms a # 14 pass. The dot with the pixel position number (3 + 4 × n) forms the # 2 pass, and the dot with the pixel position number (4 + 4 × n) forms the # 6 pass. In the first example, Is different in that the path is formed.

  FIG. 14 is an explanatory diagram showing pixels recorded by dots in each pass in the first example and the second example of the dot recording method of the present invention. As shown in the figure, the (4 + 4 × m) th raster line in the second example and the (4 + 4 × m) th raster line in the first example have paths # 2, # 6, # 10, and # 14. The pixel position numbers of the pixels to be recorded are exchanged. Specifically, the (1 + 4 × n) and (2 + 4 × n) dots and the pixel position numbers (3 + 4 × n) and (4 + 4 × n) dots are interchanged. This replacement can be realized by changing the timing of the print signal PRT (i).

  In this way, by changing the timing of the drive signal in each pass and changing the pass responsible for recording each pixel position, the consecutive passes do not record the dots of pixels adjacent in the sub-scanning direction. be able to.

  However, paying attention to pixels adjacent to each other in an oblique direction between the main scanning direction and the sub-scanning direction, in this second example, there are pixels for which consecutive passes are responsible for recording. Specifically, there are paths # 4 and # 5 and paths # 8 and # 9. However, since the pixels adjacent in the oblique direction have a larger distance interval than the pixels adjacent in the main scanning direction and the sub-scanning direction, aggregation is relatively difficult to occur.

  FIG. 15 is an explanatory diagram showing a dot recording method of a third example of the dot recording method of the present invention. The parameters of this recording method are N = 20, k = 4, L = 3, and s = 5. These parameters satisfy the above-described conditions c1 'to c3'. Accordingly, printing can be executed without missing or unnecessary duplication of recorded dots. The difference from the second example shown in FIG. 13 is that the number of scan repetitions s is increased from 4 to 5, and the degree of freedom of the pixel position where each pass is responsible for recording is increased.

  FIG. 16 is an explanatory diagram showing the dot recording position of each pass in the second example and the third example of the dot recording method of the present invention. In the second example shown in FIG. 13, the position where each pass is recorded can be selected from the four pixel positions. In this third example, the pixel position numbers are (1 + 5 × n), (2 + 5 × n). ), (3 + 5 × n), (4 + 5 × n), and (5 + 5 × n), the pixel positions to be recorded by each pass can be selected. As a result, in the third example, it is possible to perform recording so that there is no continuous recording pass for pixels adjacent in an oblique direction.

  FIG. 17 is an explanatory diagram showing a fourth example of the dot recording method of the present invention. The difference from the second example shown in FIG. 13 is that the sub-scan feed is irregular feed. In this fourth example, the raster lines assigned to some passes are replaced by changing the sub-scan feed from the regular feed to the irregular feed. Specifically, the pixels to be recorded are switched between the # 5 pass and the # 6 pass, and between the # 9 pass and the # 10 pass.

  FIG. 18 is an explanatory diagram showing the dot recording position of each pass in the second example and the fourth example of the dot recording method of the present invention. Comparing the dot recording positions of each pass in the second example and the fourth example, the # 5 pass records the (1 + 4 × m) th raster line in the second example. In the example, the (4 + 4 × m) th raster line is recorded. On the other hand, the # 6 pass records the (4 + 4 × m) th raster line in the second example, but records the (1 + 4 × m) th raster line in the fourth example. Also, the paths # 9 and # 10 are interchanged in the same manner.

  The raster lines for which printing is in charge can be replaced by partially changing the sub-scan feed amount L of each pass. Specifically, as shown in FIG. 17, the replacement of the # 5 path and the # 6 path is performed in the fourth example with respect to the constant feed amount L = 3 in the fourth example. This is possible by sending the 5th pass with the sub-scan feed amount L = 2, the # 6 pass with the sub-scan feed amount L = 5, and the # 7 pass with the sub-scan feed amount L = 2. . The replacement of the # 9 pass and the # 10 pass can be similarly performed by adjusting the sub-scan feed amount.

  As can be understood from the first to fourth examples of the dot recording method described above, the pixels that each pass is responsible for recording are changed by adjusting the timing of the drive signal in each pass and the sub-scan feed amount in each pass. can do. In this way, by appropriately changing the pixels in which each pass is in charge of recording, it is possible to shift the recording timing of adjacent pixels, thereby preventing aggregation and suppressing deterioration of the printed image. it can.

  FIG. 19 is a diagram illustrating the relationship between the ink duty and the recording rate of each ink when reproducing a certain color when an ideal ink is used. As described above, the ink duty is a value representing the total ink amount per unit area, and is a total value of the recording rates of the respective inks. For example, in the combination when the ink duty is 100% in FIG. 19, the cyan (C) recording rate is 20%, the magenta recording rate is 35%, and the yellow (Y) recording rate is 45%. The color recording rate is 0%.

  By the way, with an ideal ink, for example, the color reproduced by cyan with a recording rate of 10%, magenta with a recording rate of 10%, and yellow with a recording rate of 10% is the same as a monochrome black color with a recording rate of 10%. Become. Therefore, if the cyan, magenta, and yellow recording rates are reduced by 5% and the monochrome black recording rate is increased by 5%, the same color can be reproduced. For this reason, there is no difference in the ideal ink between the color when the ink duty in FIG. 19 is 60% and the color when the ink duty is 100%.

  As described above, the combination of the recording rates of a plurality of ink colors for reproducing the same one color varies depending on the ink duty. It can also be seen that the black ink recording rate (ie, the amount of ink per unit area) may be increased in order to reduce the ink duty. In reality, when the black ink recording rate is increased, problems such as graininess of black ink dots and exposure of the background of the printing medium become apparent. Therefore, the black ink recording rate is affected by these problems and the printing medium. It is determined in consideration of a trade-off between the maximum allowable value of the ink duty.

  As described above, the combination of the recording rates of a plurality of ink colors for reproducing the same one color changes depending on the ink duty. Therefore, according to the maximum allowable value of the ink duty, the color conversion table LUT ( It can be seen that it is preferable to change FIG. Therefore, it is preferable to use a color conversion table LUT corresponding to such a print medium in order to print cleanly on a print medium with a small amount of ink absorption. Specifically, when a synthetic resin is selected as a printing medium, a color conversion table LUT for a data recording medium made of a synthetic resin may be selected.

  In addition, in order to increase the number of gradations, a low density ink such as a light cyan ink (FIG. 19) is often used, but the use of a low density ink increases the ink duty. Therefore, for the hues for which a plurality of the same hue inks can be used, print data is generated so that only the relatively high density ink is used without using the lowest density ink among the plurality of the same hue inks. By doing so, it can be seen that aggregation of ink droplets can be suppressed. In order to generate such print data, specifically, a color conversion table LUT for a synthetic resin data recording medium is premised on the use of only dark ink regardless of the maximum allowable ink duty. What you want to do.

  As described above, if a color conversion table LUT suitable for a data recording medium made of synthetic resin is used, it is possible to restrict ink duty and suppress ink aggregation, and to deteriorate the quality of a printed image. Can be suppressed.

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

  In the above embodiment, the CD-R print mode is exemplified by a resolution of 1440 × 720 and a print direction of unidirectional printing. However, for example, even in the case of 720 × 720 or bi-directional printing with a lower resolution, the main scanning speed or the sub-scan feed speed itself is reduced to constitute a printing mode with the slowest printing speed, and for CD-R The print mode may be employed.

  The present invention can be applied not only to color printing but also to monochrome printing. Further, the present invention can be applied to printing that expresses multiple gradations by expressing one pixel with a plurality of dots. It can also be applied to a drum printer. In the drum printer, the drum rotation direction is the main scanning direction, and the carriage traveling direction is the sub-scanning direction. The present invention can be applied not only to an ink jet printer but also to a dot recording apparatus that generally records on the surface of a print medium using a recording head having a plurality of nozzle arrays.

  In the above embodiment, a part of the configuration realized by hardware may be replaced with software, and conversely, a part of the configuration realized by software may be replaced by hardware. For example, part or all of the functions of the printer driver 96 shown in FIG. 1 can be executed by the control circuit 40 in the printer 20. In this case, part or all of the functions of the computer 90 serving as a print control apparatus for creating print data are realized by the control circuit 40 of the printer 20.

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

DESCRIPTION OF SYMBOLS 20 ... Printer 21 ... Display part 22 ... Paper feed motor 24 ... Carriage motor 26 ... Platen 28 ... Print head 30 ... Carriage 32 ... Operation panel 34 ... Sliding shaft 36 ... Drive belt 38 ... Pulley 39 ... Position sensor 40 ... Control circuit 41 ... CPU
44 ... RAM
DESCRIPTION OF SYMBOLS 50 ... Dedicated circuit 52 ... Head drive circuit 54 ... Motor drive circuit 55 ... Scanner control circuit 56 ... Connector 60 ... Print head unit 80 ... Scanner 90 ... Computer 91 ... Video driver 95 ... Application program 96 ... Printer driver 97 ... Resolution conversion module 98 ... Color conversion module 99 ... Halftone module 100 ... Rasterizer 102 ... User interface unit 104 ... Print mode table 220 ... Original drive signal generation unit 222 ... Mask circuit LUT ... Color conversion table PE ... Piezo element

Claims (6)

Printing is performed on a synthetic resin medium whose printing speed is lower than the printing speed in the printing mode for executing printing on the paper medium and the printing mode for executing printing on the paper medium. A printing mode for, and
A printing apparatus characterized in that a printing speed in a printing mode for executing printing on a CD-R is slower than a printing speed in a printing mode for executing printing on the synthetic resin medium. . The printing apparatus according to claim 1,
A printing apparatus, wherein a main scanning speed in a printing mode for executing printing on the CD-R is slower than a main scanning speed in a printing mode for executing printing on the synthetic resin medium. The printing apparatus according to claim 1 or 2,
The printing apparatus, wherein a sub-scanning speed in a printing mode for executing printing on the CD-R is slower than a sub-scanning speed in a printing mode for executing printing on the synthetic resin medium. The printing apparatus according to any one of claims 1 to 3,
The maximum ink weight in a printing mode for executing printing on the CD-R is smaller than the maximum ink weight in a printing mode for executing printing on the synthetic resin medium. Printing is performed on a synthetic resin medium whose printing speed is lower than the printing speed in the printing mode for executing printing on the paper medium and the printing mode for executing printing on the paper medium. A printing mode for, and
Printing speed in the printing mode for performing printing on C D-R is characterized by slower than the printing speed in the printing mode for performing printing on the synthetic resin medium, a printing method . Printing is performed on a synthetic resin medium whose printing speed is lower than the printing speed in the printing mode for executing printing on the paper medium and the printing mode for executing printing on the paper medium. A printing mode for, and
Printing speed in the printing mode for performing printing on C D-R is characterized by slower than the printing speed in the printing mode for performing printing on the synthetic resin medium, the printing A printing program realized by a computer.

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