JPH1191088A - Method and device for dot recording having low resolution recording mode as well as recording medium wherein program for executing dot recording is recorded - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a dot for a low resolution, which is provided with a comparatively large size, without duplicating the same ink by a multitude of times. SOLUTION: In low resolution recording mode, a plurality of kinds of inks, different in at least one of concentration or color phase, are discharged respectively between the same main scans so as to be duplicated at the same position of dot whereby a dot, suitable for a dot pitch in the low resolution recording mode, is formed. In a first method for forming the dot of large size, a plurality of the kinds of the same color inks, having the same color substantially but different in concentration, are discharged so as to be duplicated on the same position of dot. In a second method, one kind of ink, selected from cyanogen ink, magenta ink and yellow ink, and black ink are discharged so as to be duplicated. In a third method, two kinds of inks, selected from cyanogen ink, magenta ink and yellow ink, are discharged so as to be duplicated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a dot recording technique using a dot recording apparatus having high-resolution and low-resolution recording modes, and more particularly to a dot forming technique in a low-resolution recording mode.

[0002]

2. Description of the Related Art In recent years, as an output device of a computer,
2. Description of the Related Art A color printer of a type that discharges a plurality of colors of ink from a head has become widespread, and is widely used for printing an image processed by a computer or the like in multiple colors and multiple gradations. When printing with a printer, there are cases where it is desired to create a high-resolution and high-quality printed matter, and cases where it is desired to create a high-speed printed matter even at a low resolution. At high resolution, small dots are formed at a small pitch, and at low resolution, large dots are formed at a large pitch. Conventionally, in order to perform printing at a low resolution, the size of a dot is increased by overlapping the same ink many times.

[0003]

However, in order to overlap the same ink many times, it is usually necessary to increase the number of scans on the same line. For this reason, there is a problem that the recording speed does not become too high despite recording at a low resolution.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems in the prior art, and can form relatively large dots for low resolution without overlapping the same ink many times. It aims to provide technology.

[0005]

In order to solve at least a part of the above-mentioned problems, an apparatus according to the present invention uses a dot recording head to record dots on the surface of a recording medium. An apparatus, a dot recording head including a plurality of sets of nozzle arrays for discharging a plurality of types of inks, and main scanning driving means for performing main scanning by driving at least one of the dot recording head and the recording medium. A head driving means for driving at least a part of a plurality of nozzles included in the dot recording head to form dots during the main scanning; and each time the main scanning ends, the dot recording head and A sub-scanning driving unit that performs sub-scanning by driving at least one of the recording media; and a control unit that controls each of the units. A low-resolution printing mode for printing at a small dot pitch, and a high-resolution printing mode for printing at a relatively small dot pitch. In the low-resolution printing mode, at least one of density and hue is different. By discharging a plurality of types of inks during the same main scan so as to overlap the same dot positions, relatively large-sized dots suitable for the dot pitch in the low-resolution recording mode are formed. I do.

In the above apparatus, a plurality of types of ink are ejected during the same main scan so as to be overlapped at the same dot position.
Relatively large dots for low resolution can be formed.

In the low-resolution recording mode, it is preferable that a plurality of types of inks of the same color, which have substantially the same color and different densities, are ejected so as to overlap the same dot position. In this way, relatively large-sized dots can be formed with substantially the same color ink.

In addition, as the plurality of types of same-color inks having different densities, it is preferable to use inks for at least two types of primary colors, cyan and magenta.
Inks having substantially the same color but different densities are often used for cyan and magenta to improve image quality. Therefore, for at least these primary colors, dots of a relatively large size can be formed by overlapping a plurality of types of the same color inks having different densities.

Alternatively, in the low-resolution recording mode, at each dot position, two kinds of inks, one of cyan ink, magenta ink and yellow ink, and black ink are ejected in a superposed manner. In this way, the relatively large size dots are formed, and the first dot position where cyan ink is ejected, the second dot position where magenta ink is ejected, and the third dot where yellow ink is ejected. By arranging the first to third dot positions so that the positions have a distribution substantially equivalent to each other, it is also possible to record an area that is macroscopically recognized as a gray color.

In this way, a relatively large dot for low resolution can be formed without overlapping the same ink many times, and an area that is macroscopically recognized as a gray color can be recorded.

Alternatively, in the low resolution recording mode, at each dot position, two kinds of inks selected from cyan ink, magenta ink and yellow ink are ejected in a superposed manner, so that the relatively large-sized dots are ejected. And the first dot position at which cyan ink is ejected, the second dot position at which magenta ink is ejected, and the third dot position at which yellow ink is ejected, are substantially equivalent to each other. By arranging the first to third dot positions so as to have an area, a region macroscopically recognized as a gray color may be recorded.

Also in this case, a relatively large-sized dot for low resolution can be formed without overlapping the same ink many times, and an area which is macroscopically recognized as a gray color can be recorded.

The method according to the present invention uses a dot recording apparatus capable of performing recording in a low-resolution recording mode for recording at a relatively large dot pitch and a high-resolution recording mode for recording at a relatively small dot pitch. A method of recording dots, wherein in the low resolution recording mode, a plurality of types of inks having different densities and / or hues are respectively ejected during the same main scan so as to overlap the same dot positions. By doing so, a relatively large dot suitable for the dot pitch in the low resolution recording mode is formed.

The recording medium according to the present invention is used in a dot recording apparatus having a dot recording head and a computer, and stores a computer program for recording dots on the surface of the recording medium using the dot recording head. A computer-readable recording medium having recorded thereon, wherein the computer program is stored in the computer in a low-resolution recording mode in which recording is performed at a relatively large dot pitch and a high-resolution recording mode in which recording is performed at a relatively small dot pitch. Has a function of executing printing, the low-resolution printing mode, by discharging a plurality of types of ink at least one of the density and hue different so as to overlap the same dot position,
The low-resolution recording mode is a mode for forming relatively large-sized dots suitable for the dot pitch.

According to these methods and recording media, similarly to the above-described dot recording apparatus, relatively large-sized dots for low resolution can be formed without overlapping the same ink many times.

As a recording medium, a flexible disk, a CD-ROM, a magneto-optical disk, an IC card,
Various computer-readable media such as a ROM cartridge, a punched card, a printed matter on which a code such as a barcode is printed, an internal storage device (memory such as RAM and ROM) and an external storage device of the computer can be used.

[0017]

Other Embodiments of the Invention The present invention includes the following other embodiments. A first aspect is an aspect as a program supply device that supplies a computer program for realizing the functions of each step or each means of the above-described invention to a computer via a communication path. In such an embodiment, the above-described method and apparatus can be realized by placing the program on a server or the like on a network, downloading the necessary program to a computer via a communication path, and executing the program.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION

A. First Embodiment An embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing a configuration of a printing apparatus as one embodiment of the present invention. As shown, the scanner 12 and the color printer 22 are connected to the computer 90, and a predetermined program is loaded and executed on the computer 90, so that the computer 90 functions as a printing apparatus as a whole. The hardware as the printing device is a normal computer 90. As shown
The computer 90 includes the following units interconnected by a bus 80, centering on a CPU 81 that executes various arithmetic processes for controlling operations related to image processing according to a program. The ROM 82 previously stores programs and data necessary for the CPU 81 to execute various arithmetic processes, and the RAM 83 temporarily reads and writes various programs and data necessary for the CPU 81 to execute various arithmetic processes. Memory. The input interface 84 controls input of signals from the scanner 12 and the keyboard 14, and the output interface 85 controls output of data to the printer 22. The CRTC 86 controls signal output to the CRT 21 capable of color display, and the disk controller (DDC) 87
Or a flexible drive 15 or a CD-not shown
Controls data transfer to and from the ROM drive. The hard disk 16 stores various programs loaded and executed in the RAM 83 and various programs provided in the form of device drivers. other than this,
The bus 80 has a serial input / output interface (SI
O) 88 is connected. The SIO 88 is connected to the modem 18, and is connected to the public telephone line PNT via the modem 48. The computer 90 is connected to an external network via the SIO 88 and the modem 18. By connecting to a specific server SV, it is also possible to download a program required for image processing to the hard disk 76. Necessary programs are stored on a flexible disk FD or C
It is also possible to load the data from the D-ROM and make the computer 90 execute the data.

FIG. 2 is a block diagram showing the configuration of software related to print processing. 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 the final color image data FNL is output from the application program 95 via these drivers. An application program 95 for performing image retouching and the like includes:
The image is read from the scanner, and the image is displayed on the CRT display 93 via the video driver 91 while performing predetermined processing on the image. When the application program 95 issues a print command, the printer driver 96 of the computer 90 receives the image information from the application program 95, and receives the image information from the application program 95 as a signal that can be printed by the printer 22 (here, a binary signal for each ink color). Signal). In the example shown in FIG. 2, a rasterizer 97 that converts color image data handled by the application program 95 into image data in dot units is provided inside the printer driver 96.
A color correction module 98 that performs color correction on the image data in units of dots in accordance with the characteristics of the ink colors and colors used by the printer 22, a color correction table CT referred to by the color correction module 98, And a halftone module 99 that generates so-called halftone image information that expresses the density in a certain area based on the presence or absence of ink in dot units from the image information.

FIG. 3 is a schematic configuration diagram of the printer 22. As shown in the figure, the printer 22 includes a mechanism for transporting a sheet P by a paper feed motor 23, a mechanism for reciprocating a carriage 31 in the axial direction of a platen 26 by a carriage motor 24, and a print head mounted on the carriage 31. And a control circuit 40 for exchanging signals with the paper feed motor 23, the carriage motor 24, the print head assembly 60 and the operation panel 32. Have been.

The carriage 31 of the printer 22 includes
A black ink cartridge 71 and a color ink cartridge 72 can be mounted. At the bottom of the carriage 31, an introduction pipe 65 (see FIG. 4) for guiding ink from the ink tank to each ink head of the print head assembly 60 is provided upright. When the black ink cartridge 71 and the color ink cartridge 72 are mounted on the carriage 31 from above, an introduction tube is inserted into a connection hole provided in each cartridge, and ink is supplied from each ink cartridge to the print head assembly 60. Becomes possible.

A mechanism for discharging ink will be briefly described. Ink cartridges 71 and 72 are carriage 31
The ink in the ink cartridge is sucked out through the introduction tube 65 by utilizing the capillary phenomenon, and guided to the nozzles of each color of the print head assembly 60 provided below the carriage 31. When the ink cartridge is first mounted, the operation of sucking the ink into the print head assembly 60 is performed by a dedicated pump. In this embodiment, a pump for suction and covering the print head assembly 60 at the time of suction are provided. Illustration and description of the configuration of the cap and the like are omitted.

As shown in FIG. 4, the print head assembly 60 is provided with a plurality of nozzles n for each color, and is one of the electrostrictive elements for each nozzle and has excellent responsiveness. A piezo element PE is arranged. FIG. 5 shows the structure of the piezo element PE and the nozzle n in detail. As shown in the drawing, the piezo element PE is provided at a position in contact with an ink passage 66 for guiding ink to the nozzle n. As is well known, the piezo element PE is an element that distorts the crystal structure due to the application of a voltage and converts electro-mechanical energy very quickly. In the present embodiment, by applying a voltage having a predetermined time width between the electrodes provided at both ends of the piezo element PE, the piezo element PE expands by the voltage application time as shown in the lower part of FIG. One side wall 66 is deformed. As a result, the volume of the ink passage 66 contracts in accordance with the expansion of the piezo element PE, and the ink corresponding to this contraction becomes particles Ip and is discharged from the tip of the nozzle n at a high speed. When the ink particles Ip soak into the paper P mounted on the platen 26, printing is performed.

In the printer 22 having the above-described hardware configuration, the carriage 31 is reciprocated by the carriage motor 24 while the sheet P is conveyed by rotating the platen 26 and other rollers by the paper feed motor 23, and at the same time, the print head The piezo element PE of each ink nozzle of the assembly 60 is driven to eject each color ink, and a multicolor image is formed on the paper P. The specific arrangement of each ink nozzle will be further described later.

The mechanism for transporting the paper P is a paper feed motor 2
A gear train (not shown) for transmitting the rotation of No. 3 not only to the platen 26 but also to a paper transport roller (not shown) is provided. The mechanism for reciprocating the carriage 31 includes an endless drive belt 36 extending between the carriage motor 24 and a slide shaft 34 erected in parallel with the axis of the platen 26 and slidably holding the carriage 31. Pulley 38,
Position detection sensor 3 for detecting the origin position of carriage 31
9 and so on.

In the control circuit 40 (FIG. 3), a programmable ROM (PROM) 42 as a rewritable nonvolatile memory is provided in addition to a CPU and a main memory (ROM and RAM) not shown. PRO
In M42, dot recording mode information including a plurality of dot recording mode parameters is stored. here,
"Dot recording mode" refers to the recording resolution, scanning speed,
The number N of nozzles actually used in each nozzle array,
This means a dot recording method defined by the sub-scan feed amount L and the like. In this specification, the “recording method” and the “recording mode” are used with almost the same meaning. The PROM 42 further stores mode designation information for designating a preferred mode from a plurality of dot recording modes. ing. For example, when 16 types of dot recording mode information can be stored in the PROM 42, the mode designation information is composed of 4-bit data.

The dot recording mode information is stored in the computer 9
When the printer driver 96 (FIG. 2) is installed at the start of
It is read from M42. That is, the printer driver 96 stores the dot recording mode information for the preferred dot recording mode designated by the mode designation information in the PROM 42.
Read from. The processing in each module of the printer driver 96 (FIG. 2) and the operation of main scanning and sub-scanning are as follows.
This is executed according to the dot recording mode information.

The PROM 42 may be any rewritable nonvolatile memory, and various nonvolatile memories such as an EEPROM and a flash memory can be used. Although the mode designation information is preferably stored in a rewritable nonvolatile memory, the dot recording mode information may be stored in a non-rewritable ROM. The plurality of dot recording mode information is PR
Instead of the OM 42, it may be stored in another storage unit, or may be registered in the printer driver 96.

FIG. 6 is a diagram showing the structure of a print head assembly according to the first embodiment of the present invention. The print head assembly 60 is separated into two print heads 61 and 62. The two print heads 61 and 62 are fixed to each other by fixing means such as screwing, and are assembled as one print head assembly 60.

[0030] The first print head 61, and the dark black ink nozzle group K _D, and light black ink nozzle group K _L is formed. On the other hand, the second print head 62 includes
A dark cyan ink nozzle group C _D, light cyan ink nozzle group C _L, and dark magenta ink nozzle group M _D, light magenta ink nozzle group M _L, dark yellow ink nozzle group Y
And _D, a light and a yellow ink nozzle group Y _L are formed. Each nozzle group of one ink includes 128 nozzles # 1 to # 128.

In this specification, the four primary colors (black, cyan, magenta, and yellow) of the printing ink are referred to as primary colors. The dark ink and the light ink mean relatively high-density ink and relatively low-density ink having substantially the same color. Strictly speaking, the dark ink and the light ink not only have different densities, but also have slightly different hues and saturations. However, in this specification, strictly speaking, two types of inks having different densities that are recognized as having substantially the same color even though the hue and saturation are slightly different are referred to as “dark inks”.
And "light ink".

The 128 nozzles of each ink group are aligned in a straight line along the sub-scanning direction SS. Eight nozzles assigned the same nozzle number in each nozzle group are arranged so as to be aligned on a straight line along the main scanning direction MS. As described above, the eight nozzles that eject different inks are aligned on a straight line along the main scanning direction MS mainly because the dots of different colors are shifted in the sub-scanning direction. This is for preventing the deterioration of the image quality that occurs. As will be described later, by discharging two nozzles (e.g. nozzle K _D, K _L) of the eight nozzles arranged in a straight line along the main scanning direction MS from to overlap the ink at the same position Thus, large-sized dots for low resolution can be formed.

FIG. 7 is an explanatory diagram showing a general relationship between resolution and dot diameter. The dashed line shown in FIG.
The boundary of an area (referred to as “one dot area”) 200 to be covered by one dot 202 is shown. The width of one dot area 200 is defined by a dot pitch w [μm]. The shape of each dot 202 is substantially circular, and the diameter thereof is determined so as to cover the printing paper without gaps. As shown in FIG. 7A, when each dot 202 is accurately formed at the center of one dot area 200, the diameter of each dot 202 is √2 times the dot pitch w. However, in reality, FIG.
As shown in (B), the position of the dot is one dot area 20.
Some deviation from 0. In consideration of the dot positioning error ε, the diameter D of the actually formed dot 204 is (√2 ×
w + 2 × ε).

FIG. 8 is an explanatory diagram showing an actual example of the relationship between the resolution and the dot diameter. As shown in FIG. 8A, when the resolution is 600 dpi, the dot pitch w1 is about 42 dots.
μm. Assuming that the dot positioning error ε is 10 μm, the diameter D1 of the dot 210 for 600 dpi is about 80 μm (= √2 × 42 + 2 × 10). On the other hand, as shown in FIG. 8B, when the resolution is 360 dpi, the dot pitch w2 is about 70 μm. Assuming that the dot positioning error ε is 10 μm, the diameter D2 of the dot 220 for 360 dpi (shown by a broken line) is about 120 μm.
m (= √2 × 70 + 2 × 10). FIG.
(B) shows dots 21 for 600 dpi for reference.
The size of 0 is also drawn.

The dot 210 for 600 dpi (diameter D1
= 80 μm) and dots 220 for 360 dpi (diameter D
2 = 120 μm) have considerably different sizes (areas), and therefore the amount of ink required to form them is also significantly different. FIG. 9 is a graph showing the relationship between the ink ejection amount and the dot diameter in the first embodiment. Diameter 8
In order to form a dot of 0 μm, the ink ejection amount is 20
ng is required, and an ink ejection amount of 40 ng is required to form a dot having a diameter of 120 μm. The amount of ink ejected from each nozzle can be adjusted to some extent by controlling the waveform of the drive signal for the piezo element. However, dots 210 and 360d for 600 dpi
In the case of the pi dot 220, the difference in the required ejection amount is large, so that it may be difficult for a normal nozzle to form both dots by one ejection. In this embodiment, the adjustment range of the ink ejection amount of each nozzle is 5 ng.
It is assumed to be in the range of ~ 20ng.

By controlling the ink ejection amount within the adjustment range shown in FIG. 9, the area gradation of each dot can be adjusted, and the gradation of the image is reproduced using the dot area gradation. However, details are omitted here. If the dot 210 for 600 dpi and the dot 220 for 360 dpi are simply formed without adjusting the area gradation of the dots, the ejection amount control of each nozzle is not performed.
20 ng of ink may always be ejected.

When a nozzle having the characteristics shown in FIG. 9 is used, the ink ejection amount of 20 ng required for the dot 210 for 600 dpi can be obtained by one ejection of one nozzle. On the other hand, the ink ejection amount of 40 ng required for the dot 220 for 360 dpi is twice the ink ejection amount of 20 ng required for the dot 210 for 600 dpi.
Therefore, the dots 220 for 360 dpi can be formed by ejecting 20 ng of ink from each of the two nozzles. In the first embodiment, as shown in FIG.
A dark ink nozzle group and a light ink nozzle group are provided for each of the primary colors. Therefore, for each primary color, by ejecting 20 ng dots at the same pixel position using dark ink nozzles and light ink nozzles,
It is possible to form the dots 220 for 360 dpi.

As can be understood from FIG. 6, during the main scanning,
Eight nozzles that eject eight different inks sequentially pass on the same raster (main scanning line) on the printing paper. That is, the same pixel position on the same raster, through a nozzle of the first light yellow ink nozzle group Y _L, then the nozzle of the dark yellow ink nozzle group Y _D, light nozzle of the magenta ink nozzle group M _L, conc. going through the nozzle ... order of the magenta ink nozzle group M _D. For example, 3
When forming a yellow dot 60dpi, first light 20ng from the nozzle of the yellow ink nozzle group Y _L
Pale yellow ink ejecting, then the diameter 120μm by ejecting dark yellow ink 20ng from the nozzle of the dark yellow ink nozzle group Y _D at the same pixel position of
Is formed (FIG. 8B).

A dot formed by ejecting light ink and dark ink of the same color at the same position has an intermediate density between light ink and dark ink. Such a difference in dot density affects image processing (specifically, processing in the color correction module 98 and the halftone module 99 in FIG. 2). Therefore, when the dot diameter is increased by discharging light ink and dark ink of the same color to the same position, the contents of these image processings are changed according to the color of the dots to be formed.

It is preferable that the light ink and the dark ink are ejected in the order of the light ink first, as in the first embodiment. The reason for this is that when the light ink is ejected later, the light ink spreads around the dark ink, so that the density change between the periphery and the center of the dot tends to be larger than when the dark ink is ejected first. It is.

In the above-described first embodiment, large-sized dots are formed by sequentially ejecting inks of the same color and different densities at the same position during one main scan. The main scanning speed of the carriage 31 (FIG. 1)
Since it is proportional to the reciprocal of the resolution, for example, printing at 360 dpi can perform main scanning at a speed that is 5/3 times faster than printing at 600 dpi. Further, since the number of raster lines at 360 dpi is の of the number of raster lines at 600 dpi, the printing speed in the sub-scanning direction is also ／ of 600 dpi. Therefore, printing at 360 dpi is equivalent to printing at 600 dpi.
It is possible to perform printing at a speed about 25/9 times faster than the printing at the same time. A mode in which dot recording is performed at a low resolution of 360 dpi is called a high speed mode, and a high resolution 600 dpi is used.
The mode in which dot recording is performed can be called a low speed mode (high image quality mode).

In the first embodiment, the relatively large dot 220 is formed with an ink amount twice as large as the maximum ejection amount (20 ng) of one nozzle. However, the present invention is not limited to this.
It is possible to print a dot of a large size that is formed with an ink amount equal to or more than the maximum ejection amount of one nozzle and twice or less of the maximum ejection amount of one nozzle.

B. Second Embodiment FIG. 10 shows a second embodiment of the present invention.
FIG. 3 is a diagram illustrating a configuration of a print head assembly according to the embodiment. The first print head 61 'are dark black ink nozzle group K _D of forming the second print head 62', the the dark cyan ink nozzle group C _D, and dark magenta ink nozzle group M _D, a dark yellow ink nozzle group Y _D, light cyan ink nozzle group C _L, and the light magenta ink nozzle group M _L is formed. The print head assembly of the second embodiment differs from the print head assembly of FIG. 6 in that the light yellow ink nozzle group YL and the light black nozzle group KL are not provided. The nozzle of the dark yellow ink nozzle group Y _D has a larger diameter than the nozzles of the other ink, thus, it is formed so as to be able to eject more ink.

FIG. 11 is a graph showing the relationship between the ink ejection amount and the dot diameter in the second embodiment. Each of the nozzles that eject cyan ink, magenta ink, and black ink can eject ink in the range of 5 ng to 20 ng at a time. On the other hand, a nozzle that discharges yellow ink can discharge 10 to 40 ng of ink at a time.
Each nozzle can adjust the area gradation of the dot within these adjustment ranges.

Of the four primary colors, cyan and magenta are obtained by ejecting light ink and dark ink so as to overlap at the same position, as in the first embodiment.
The dots 220 for 60 dpi can be formed.
For yellow, the nozzle adjustment range is 600 dp
The required ejection amount (20 ng) of the dot 210 for i and 360
Since it includes the required ejection amount (40 ng) of the dots 220 for dpi, the dots 220 of 360 dpi can be formed by one ejection.

With respect to black, by discharging four kinds of inks of a deep black ink, a deep cyan ink, a deep magenta ink, and a deep yellow ink so as to be overlapped at the same position, the dots 220 dots for 360 dpi are formed.
Can be formed. In this case, the ejection amounts of the four types of ink can be a combination of a plurality of types. For example, dark cyan ink, dark magenta ink, and dark yellow ink are each ejected by 10 ng (the minimum possible ejection amount of dark yellow ink), and one dark black ink is ejected.
By ejecting 0 ng, the dots 220 for 360 dpi can be formed. Alternatively, by ejecting about 13 ng each of dark cyan ink, dark magenta ink and dark yellow ink, it is possible to form 360 dpi dots 220 without ejecting dark black ink. Note that the ejection amounts of the dark cyan ink, the dark magenta ink, and the dark yellow ink do not necessarily need to be equal, and are actually adjusted so that the gray balance can be obtained (that is, when the three color inks are mixed, they become gray. ) Each discharge amount is determined.

By providing nozzles for ejecting dark ink and light ink at least for cyan and magenta as in the second embodiment, large-sized dots and small-sized dots can be formed for each color. Is possible. At this time, it is preferable that the yellow nozzle is configured such that large-sized dots and small-sized dots can be respectively formed by one ejection.

C. Embodiment for Gray Image: If the image is not a color image but a gray image, large-sized dots and small-sized dots can be formed as follows. FIG. 12 shows dots 210 and 360d for 600 dpi for reproducing a gray image in the third embodiment.
FIG. 3 is an explanatory diagram showing a configuration of a dot 220 for pi. FIG.
As shown in FIG. 2A, a small dot 210 for 600 dpi is formed by discharging 20 ng of black ink once.

On the other hand, as shown in FIG.
The large dot 220 for dpi first discharges 20 ng of any one of cyan ink, magenta ink, and yellow ink, and deposits 20 ng of black ink at the same position.
It is formed by discharging ng. In this case, the first dot position where cyan ink is ejected, the second dot position where magenta ink is ejected, and the third dot position where yellow ink is ejected are regular and equivalent to each other. Are arranged so as to have an appropriate distribution. As a result, the region macroscopically recognized as gray is 36
It can be recorded at 0 dpi.

FIG. 13 is an explanatory view showing a mask used in the third embodiment. This mask has a 3 × 3 dot area, and defines which ink should be ejected at each dot position. For example, black ink and cyan ink are ejected at the upper left dot position. In the case of printing a macroscopic gray area, such a mask is repeatedly applied to the gray area.
Each ink can be ejected in the arrangement shown in FIG.

In the example shown in FIG. 12B, ink is ejected at all dot positions. However, when the gray density is low, ink is not ejected at some dot positions. Is also possible. In such a case, the regularity of the dot positions where the cyan, magenta, and yellow inks are ejected is somewhat impaired. However, also in this case, in order to macroscopically recognize the gray color, the ejection positions of the respective inks are determined so as to have substantially equivalent distributions to each other.

FIG. 14 shows dots 210 and 36 for 600 dpi for reproducing a gray image in the fourth embodiment.
FIG. 3 is an explanatory diagram illustrating a configuration of a dot 220 for 0 dpi.
The small-sized dot 210 for 600 dpi shown in FIG. 14A is formed by discharging 20 ng black ink once, as in the third embodiment.

On the other hand, as shown in FIG.
The large dots 220 for dpi are formed by ejecting 20 ng of two types of ink selected from cyan ink, magenta ink and yellow ink at the same position without using black ink. You. In this case, as in the third embodiment, the first dot position where cyan ink is ejected, the second dot position where magenta ink is ejected, and the third dot position where yellow ink is ejected. Are arranged so as to have distributions substantially equivalent to each other. As a result, an area macroscopically recognized as gray can be recorded at 360 dpi.

FIG. 15 is an explanatory view showing a mask used in the fourth embodiment. This mask also has a 3 × 3 dot area, and it is specified which ink should be ejected at each dot position. When such a mask is repeatedly applied to a macroscopic gray area when printing is performed, each ink can be ejected in the arrangement shown in FIG. 14B.

In the above-described third and fourth embodiments, large-sized dots can be formed by ejecting two types of inks of different colors at the same position so that a gray image can be formed in the high-speed mode. It is possible to record.

It should be noted that the present invention is not limited to the above-described examples and embodiments, but can be implemented in various modes without departing from the scope of the invention.
For example, the following modifications are possible.

(1) In the above embodiment, the high resolution is set to 600
Although the resolution is set to 360 dpi and the low resolution is set to 360 dpi, various combinations other than these may be considered as the combination of the high resolution and the low resolution. In general, the present invention is applied to the case where the ejection amount of ink for forming large-sized dots for low resolution is equal to or more than the maximum ejection amount of one nozzle and equal to or less than the total ejection amount of two nozzles. Applicable. Note that the ejection amounts of the two nozzles used when forming large-sized dots need not be the same.

(2) In the above embodiment, part of the configuration realized by hardware may be replaced by software, and conversely, part of the configuration realized by software may be replaced by hardware. You may do so.

[Brief description of the drawings]

FIG. 1 is an exemplary block diagram illustrating an example in which a printing apparatus according to an embodiment is configured around a computer.

FIG. 2 is a block diagram illustrating a configuration of software related to print processing.

FIG. 3 is a schematic configuration diagram illustrating a configuration of a color printer 22 as an example of an image output device 20.

FIG. 4 is an explanatory diagram showing a configuration for ejecting ink in each print head.

FIG. 5 is an explanatory diagram showing a state in which ink particles Ip are ejected by expansion of a piezo element PE.

FIG. 6 is a diagram illustrating a configuration of a print head assembly according to the first embodiment of the present invention.

FIG. 7 is an explanatory diagram showing a general relationship between resolution and dot diameter.

FIG. 8 is an explanatory diagram showing an actual example of the relationship between resolution and dot diameter.

FIG. 9 is a graph showing a relationship between an ink ejection amount and a dot diameter in the first embodiment.

FIG. 10 is a diagram showing a configuration of a print head assembly according to a second embodiment of the present invention.

FIG. 11 is a graph showing a relationship between an ink ejection amount and a dot diameter in a second embodiment.

FIG. 12 is an explanatory diagram showing a configuration of a dot 210 for 600 dpi and a dot 220 for 360 dpi for reproducing a gray image in the third embodiment.

FIG. 13 is an explanatory view showing a mask used in the third embodiment.

FIG. 14 is an explanatory diagram showing a configuration of a dot 210 for 600 dpi and a dot 220 for 360 dpi for reproducing a gray image in the fourth embodiment.

FIG. 15 is an explanatory view showing a mask used in the fourth embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 12 ... Scanner 14 ... Keyboard 15 ... Flexible drive 16 ... Hard disk 18 ... Modem 21 ... CRT 22 ... Printer 23 ... Paper feed motor 24 ... Carriage motor 26 ... Platen 28 ... Print head 31 ... Carriage 32 ... Operation panel 34 ... Sliding axis 36 ... Drive belt 38 ... Pulley 39 ... Position detection sensor 40 ... Control circuit 42 ... PROM 48 ... Modem 60 ... Print head assembly 61,62 ... Print head 65 ... Introduction tube 66 ... Ink passage 71 ... Black ink cartridge 72 ... Color ink cartridge 76 ... Hard disk 80 ... Bus 81 ... CPU 82 ... ROM 83 ... RAM 84 ... Input interface 85 ... Output interface 86 ... CRTC 88 ... SIO 90 ... Computer 91 ... Video driver 93 ... CRT data Display 95 Application program 96 Printer driver 97 Rasterizer 98 Color correction module 99 Halftone module

Claims (11)

[Claims] 1. A dot recording apparatus for recording dots on the surface of a recording medium using a dot recording head, comprising: a dot recording head including a plurality of sets of nozzle arrays for discharging a plurality of types of inks; Main scanning driving means for performing main scanning by driving at least one of a head and the recording medium; and forming dots by driving at least a part of a plurality of nozzles included in the dot recording head during the main scanning. A sub-scanning driving unit that performs sub-scanning by driving at least one of the dot recording head and the recording medium each time the main scanning ends, and a control unit that controls each of the units. The control means comprises: a low-resolution printing mode for printing at a relatively large dot pitch; and a high-resolution printing mode for printing at a relatively small dot pitch. And a plurality of inks having different densities and hues during the same main scan so as to be superimposed on the same dot position in the low-resolution print mode. A relatively large dot suitable for a dot pitch in the low resolution recording mode. 2. The dot recording apparatus according to claim 1, wherein the control means causes the plurality of types of inks of the same color and different densities to be superimposed on the same dot position in the low resolution recording mode. Dot recording device that discharges 3. The dot recording apparatus according to claim 2, wherein as the plurality of kinds of same-color inks having different densities, inks relating to at least two primary colors of cyan and magenta are used. . 4. The dot recording apparatus according to claim 1, wherein in the low-resolution recording mode, the control means selects one of cyan ink, magenta ink, and yellow ink at each dot position. Ink and
The relatively large-sized dots are formed by ejecting two types of inks, one on top of the other, with black ink, and the first dot position where cyan ink is ejected and the second dot where magenta ink is ejected By arranging the first to third dot positions so that the position and the third dot position at which the yellow ink is ejected have a distribution substantially equivalent to each other, it is macroscopically recognized as a gray color. A dot recording device that records an area. 5. The dot recording apparatus according to claim 1, wherein in the low-resolution recording mode, the control means selects at least one of a cyan ink, a magenta ink, and a yellow ink at each dot position. Forming the relatively large-sized dots by overlappingly ejecting different types of inks; a first dot position where cyan ink is ejected; a second dot position where magenta ink is ejected; By arranging the first to third dot positions so that the third dot positions where are ejected have substantially the same distribution as each other, an area that is macroscopically recognized as a gray color is recorded. Dot recording device. 6. A dot recording apparatus that can execute recording in a low-resolution recording mode for recording at a relatively large dot pitch and a high-resolution recording mode for recording at a relatively small dot pitch. In the low-resolution recording mode, by discharging a plurality of types of ink at least one of the density and the hue are different during the same main scan so as to overlap the same dot position, A dot recording method, wherein relatively large dots suitable for a dot pitch in the low resolution recording mode are formed. 7. The dot recording method according to claim 6, wherein in the low resolution recording mode, a plurality of types of same color inks of substantially the same color and different densities are ejected so as to overlap the same dot position. , Dot recording method. 8. The dot recording method according to claim 7, wherein the plurality of types of same-color inks having different densities are inks for at least two primary colors of cyan and magenta. . 9. The dot recording method according to claim 6, wherein in the low resolution recording mode, at each dot position, one ink selected from cyan ink, magenta ink, and yellow ink;
The relatively large-sized dots are formed by ejecting two types of inks, one on top of the other, on the first dot position where cyan ink is ejected and the second dot where magenta ink is ejected. By arranging the first to third dot positions so that the dot position and the third dot position at which the yellow ink is ejected have a distribution substantially equivalent to each other, it is macroscopically recognized as a gray color. Dot recording method in which an area is recorded. 10. The dot recording method according to claim 6, wherein in the low resolution recording mode, at each dot position, two types of ink selected from cyan ink, magenta ink, and yellow ink are overlapped. The relatively large-sized dots are formed by ejecting the ink, and the first dot position where the cyan ink is ejected, the second dot position where the magenta ink is ejected, and the yellow ink are ejected By arranging the first to third dot positions so that the third dot positions have substantially the same distribution as each other, an area that is macroscopically recognized as gray is recorded. . 11. A computer-readable recording device which is used in a dot recording device including a dot recording head and a computer and records a computer program for recording dots on a surface of a recording medium using the dot recording head. A medium, wherein the computer program has a function of causing the computer to execute recording in a low-resolution recording mode for recording at a relatively large dot pitch and a high-resolution recording mode for recording at a relatively small dot pitch. In the low-resolution printing mode, a plurality of types of ink having different densities and hues are ejected so as to overlap the same dot position, so that a comparison suitable for the dot pitch in the low-resolution printing mode is performed. This mode is for forming large dots. A computer-readable recording medium characterized by the above-mentioned.