JPS5853445A - Ink jet color printing system - Google Patents

Abstract

PURPOSE:To enhance weather resistance, by a method wherein component density signals for red and blue are extracted from density signals for cyan, magenta and yellow, and ink jet ejecting heads for each color are controlled by these density signals. CONSTITUTION:A colored original picture 11 is scanned in a two-dimensional manner to produce the density signals for cyan, magenta and yellow, and the component density signals, for black, red, green and blue are extracted from the density signals. Heads 46a-46c for yellow color, heads 47a-47c for magenta color, heads 48a-48c for cyan color, head 49a-49c for blue color, heads 50a- 50c for green color, heads 51a-51c for red color and heads 52a-52c for black color provided in the ink jet ejecting head part 43 for each color are controlled by the density signals, and ink dots are recorded. Accordingly, since a picture is formed by adding at least inks of intermediate hues of red and blue having good weather resistance, color reproducibility and weather resistance of intermediate hues can be enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides five color inks including cyan, magenta, yellow, and red and blue, or six colors including green.
This invention relates to an inkjet color printing method that uses color ink to draw color images.

Generally, cyan is used for inkjet color printers and inkjet color facsimiles.

In one example where magenta and yellow color inks are used to express multiple gradations, nXm (n.

A color image is drawn by injecting ink dots of up to eight colors into a dot matrix (m is an integer). The size and pattern of ink dots to be injected into this dot matrix are determined according to cyan, magenta, and yellow density signals read from the color original image and stored as single information.

The cyan, magenta, and yellow are the eight primary colors of coloring materials, and by appropriately mixing these colors, all intermediate colors can be expressed. However, since the rays actually used do not have ideal curves in terms of spectral characteristics, it is difficult to reproduce all intermediate colors. In particular, since magenta ink has sub-absorption in yellow, the color reproducibility of red obtained by mixing yellow ink with magenta ink and blue obtained by mixing cyan ink is not good. Furthermore, magenta ink has poor weather resistance, so there is a problem in that red changes to yellow and blue changes to cyan. moreover,
In the high-density areas of red and blue, there is a large amount of two-color ink adhesion, which can cause the ink to run or smear in one color, or cause the recording paper to partially stretch due to a large amount of moisture, causing wrinkles. There are also some inconveniences.

An object of the present invention is to provide an inkjet color printing method that has good color reproducibility and weather resistance for intermediate colors.

Another object of the present invention is to provide an inkjet color printing system that can prevent bleeding, wrinkles, etc. of nine colors of ink flow in a high density region of intermediate colors.

Another object of the invention is cyan, magenta.

To provide an inkjet color printing method that allows a color scanner equipped with a conventional 8-color separation photometry system to be used by removing and distributing red and blue components from a yellow density signal. There is a particular thing.

The present invention removes and distributes red component and blue component density signals from cyan, magenta, and yellow density signals.
Forming density signals of magenta, yellow, red and blue, at least cyan and magenta.

One color is drawn using six colors of ink: yellow, red, and blue. When carrying out the present invention, it is desirable to use black ink in combination to improve the appearance of dark areas.

Green is an important intermediate color that generally appears frequently.

Therefore, by removing and distributing the green component of , and drawing using six color inks, the colors "near", ゛2:t
:s't,”r *ia.5, □, 95, will be explained in detail.

In FIG. 1, an inkjet color printing apparatus implementing the present invention includes a digital color scanner 1 (color image input device) 1 an image information processing device 2. and printer 8
It consists of

The digital color scanner 1 scans each part of the color original image 1-'l wrapped around the rotating cylinder 10 to detect blue color,
Measure the concentration value that passes through each green and red filter. This rotating cylinder 10 is driven by a main scanning nozzle smoke 12, and the driving nozzle applied to the main scanning pulse motor 12 is counted by a main scanning counter 18, and the position of the rotating cylinder 10 in the main scanning direction is is detected. The main scanning counter 18 is incremented by one each time a certain reference position on the outer periphery of the rotary cylinder 10 passes a specific position. Therefore, the positions until the rotating cylinder lO makes one revolution are counted.

The illumination light emitted from the illumination light source 14 is focused by the lens 16 and illuminates a spot on the color original image 1'1. The light reflected by this color original image 11 passes through a lens 16 and enters a nof mirror 17, and the optical path is divided into two by transmission and reflection. The light reflected by the half mirror 17 passes through the blue filter 18 and reaches the blue light receiver 1.
9 and is photoelectrically converted here. Further, the light transmitted through the No.-7 mirror 17 enters the half mirror 20, where the optical path is again divided into two. The light reflected by this nof mirror 20 passes through a green filter 21 and enters a green light receiver 22. On the other hand, the light transmitted through the No.-7 mirror 20 passes through the red filter 28 and enters the red light receiver 24. These light receivers 19, 22, and 24 measure eight color light components at each point of the color painting.

The illumination light source 14, lens 15.16,... mirror 17.20, filter 18, 21.28, light receiver 19,
22 and 24 are mounted on the moving table 26. This moving table is 25 it.

It moves in parallel to the axial direction of the rotating inner cylinder 10 by the feed screw shaft 26 and the guide 27. This feed screw shaft 26 is driven by a sub-scanning pulse motor 28, and the drive pulses input to this sub-scanning pulse motor 28 are counted by a sub-scanning counter 29.

The eight color signals measured by the light receivers 19, 22, and 24 are each logarithmically converted by a logarithmic converter 80 provided for each color, and converted into a density signal.

These eight color density signals are each converted into a digital signal by an A-D converter 81 provided for each color.

In this digital color scanner 1, the rotating cylinder 10 is one
Each time it rotates, the moving table 26 moves by one scanning line in the axial direction of the rotating cylinder 10, two-dimensionally scanning each part of the color original image 1'l. By this scanning, color original image 1
Blue for each part of 1.

The reflection densities of green and red are measured and converted into r digital numbers by an AD converter 81. In addition, A-D as necessary.
It is desirable to perform processing such as removing noise components and emphasizing the 1iIII contour lines before conversion. In addition, in this embodiment, the reflected light of the color source Fii 11 is measured;
- For the original image, the transmitted light of the color original image 11 is measured using a scanner having a structure in which the rotating cylinder 10 is transparent and the illumination light source 14 is housed inside.

iI's information processing device 2 includes an interface 88, a central processing unit 84, a storage device 85, a line buffer memory section 86, a table memory section 87, and a head drive section 8.
It consists of 8. A commonly used minicomputer is used as the central processing unit 84,
It controls the digital color scanner 1 and the printer 8, controls the writing and reading of eight color density signals (one piece of information), performs masking processing for color correction, and performs image quality processing (additions and changes) such as character insertion.

When writing one bone information, a drive pulse from the central processing unit 84 is input to the main scanning pulse motor 12, and the rotary cylinder 10 is rotated in the main scanning direction.

Each time the rotating cylinder 10 rotates once, the sub-scanning pulse motor 28 rotates by a certain angle. Therefore, the color original image 11 is two-dimensionally scanned, and each pixel on the scanning line is subjected to eight-color separation photometry, logarithmically converted, and digitally converted.
4, each color density signal group of cyan, magenta, and yellow is captured. This captured Aa color density signal has a main scanning power of 1. An address corresponding to the pixel position is specified by the position signal from the counter 18 and the sub-scanning counter 29, and the 8-color #If signal is stored in the specified memory cell. ``The object of the present invention is achieved by separating the input one-time information taken in in this manner into color density components of the ink used for each pixel to obtain image information for driving the printer. In other words, the common level of the eight colors of cyan, magenta, and yellow for each pixel of the above input iik1m information is taken as the density level of black ink, and each density of cyan, magenta, and yellow after subtracting the common level of the eight colors. Red ink and green ink for the common level of each two colors.

By setting the density level to that of blue ink, a mature density signal, a red component density signal, a green component density signal, and a blue component density signal are extracted.

Since all of these density signals are digitalized binary level signals, the digital color scanner 1
Corresponding to the two-dimensional position on the color original image ll that is obtained, in the color 1 health information of each part, the density level of the binary representation of cyan, macenta, and yellow is determined by CI, respectively.
, Ml, and Yl, and black, red, green, and blue when performing inkjet drawing.

Binary density levels that control the ejection amount and/or ejection turn of each cyan, magenta, and yellow inkjet ejection head are B, RF, GP, and OF.

Assuming MP and YP, their relationship is expressed by the following logical formula.

B = C1n Mt nYt RF = (Mr −B ) n(Y+ −B ) GP
=(CI-B)n(yl-B)BP=(
Ct-B)n(Mt-B)Cp=Ct
-B -(GdeLJBF>MP = Ms -B -(
RP (J By)YP de Y Summer -B-(Rr
tJGr) (where n is a logical product symbol and U is a logical sum symbol) When displaying the concentration level in 64 steps, the specific input i
ii) The relationship between the #f level and the above-mentioned emotional axis information is expressed in decimal notation as shown in Table 1.

・1 The above is the principle logical formula and comparison table of the process of obtaining output car information from input two-axis information according to the present invention, but at the practical stage, the use of black ink at a low density level In order to prevent blurring, it is desirable to set a threshold value for the black level, not to use black ink for achromatic colors below the threshold value, and to use black ink for achromatic colors above the threshold value. Therefore, the logical formula and comparison table are as follows.

B=(01-T>n(Mt-T)n(Yx-T)Rr
= (MI-B) l'l (Yt-B)GP=
(CI-B)n(Yl-B) Br=(Cr-B)n(Ml-B) CP=CI-B-(CrLJBy)Ml=
Ml −B −(RF (J Br )Yy=Yr
-B-(RrjJGy) (where n is a logical product symbol, U is a logical sum symbol, T is a threshold value, and B
is positive only if G)T, Mt)T, Yt)T, and is 0 otherwise. ) For example, T=8
2, it will look like Table 2.

The conversion processing of these image information is carried out by the central processing unit 84.
Although this is performed by online processing or offline processing, it may also be performed by providing a dedicated arithmetic circuit for %. The procedure for obtaining an inkjet image using the image information converted in this way will be explained step by step below.

The line buffer memory section 86 stores seven different scans Im (pixels III) written simultaneously.

For this purpose, the line buffer memory section 86 is composed of seven line/buffer memories. In order to perform writing and reading at the same time, it is desirable to provide two line buffer memories for each scanning line, for a total of 14 line buffer memories.

The table memory section 87 specifies the position pattern and size of dots to be implanted into the dot matrix of the input density signal 8×8. Therefore, this table memory section 87 outputs eight dot signal strings when nine ink density signal strings are input.

The head drive section 88 is provided for each dot signal train, and is composed of eight head drive circuits for one scanning line, a total of 21 head drive circuits, and for example, 80 to 260 cm, depending on the dot signal. D/A conversion is performed by selecting one of six voltage values divided between the two voltage values, and this is modulated with a carrier signal of, for example, 20 KHz to form a head drive signal.

The inkjet printer 8 reproduces a color image by depositing ink droplets ejected from a head section 48 onto a recording medium, such as a blank sheet of paper 42 , which is wound around a rotating cylinder 41 . The rotating cylinder 41 is driven by a main scanning pulse motor 44 that receives drive pulses from a central processing unit 84 . The driving pulses applied to the main scanning pulse motor 44 are counted by a nine main scanning counter 46. The main scanning collar 45 is reset each time the rotary cylinder 41 is rotated to a certain position, and displays the relative position of the head section 48 in the main scanning direction with respect to the blank paper 42, and also displays this main scanning direction position information. The data is sent to the central processing unit 84.

The head portion 48 is close to the outer peripheral surface of the rotating cylinder 41,
Ink of the same color is ejected from 811 inkjet ejection heads arranged in the main scanning direction, and the inkjet ejection heads for color printing are arranged at appropriate intervals in the subscanning direction. That is, as shown in detail in Figure 2,
Yellow inkjet ejection heads 46a to 46c,
magenta inkjet ejection heads 47a to 47c,
Cyan inkjet discharge heads 48a to 48c, true color inkjet discharge heads 49a to 49C#a color inkjet discharge heads 501 to 50c, red inkjet discharge heads 51a to 51c, and black inkjet discharge heads 52a to 62c, respectively, in the main scanning direction. They are arranged side by side and record ink dots using a total of 21 inkjet ejection heads, 8 for each color. Each of these inkjet ejection heads is an on-demand lid type, and there are nine ink nozzles located in the center.
Nine sizes of ink droplets are ejected according to the head drive signal.

In the m×n dot matrix, if m=4, four heads for each color may be arranged in the main scanning direction. Note that since n is determined by the number of ink droplets ejected from the same head, it can be specified in terms of the circuit, regardless of the number of heads.

As shown in FIG. 8, the directions of yellow inkjet ejection heads (hereinafter simply referred to as heads) 463 to 46c are changed so that they eject ink droplets at positions shifted by one dot in the sub-scanning direction. . In this embodiment, the reference head 46m is arranged parallel to the blank paper 42, and the heads 46b and 46c are tilted by one dot.1) The blank paper 42Fi is moved in a direction perpendicular to the plane of the drawing. The dot matrix of each pixel on the scanning line Ll extending vertically Km is shown in the heads 46a to 46c.
Recorded by K.

In other words, when expressing the 1iii element with an 8 x 8 dot matrix, 2 in Yl in the main scanning direction as shown in Figure @4.
The 8 matrix cells above (YIXIXYIX2
, YIX8) are sequentially recorded by the head 46a. The head 46b sequentially records the matrix cells on line Y2, and the head 46c sequentially records the matrix cells on line Y8. Note that the grid of the dot matrix is a virtual line for indicating the positions of dots.

Since the nozzles of the heads 46b to 46c are arranged apart from each other in the main scanning direction, the signal is delayed with respect to the reference head 46m by a dot corresponding to this distance, and the same color ink is aligned.

Similarly, magenta heads 47a to 47c, cyan heads 488 to 48c, blue heads 49a to 49c, green heads 50a to 50c, red heads 61a to 51c,
The black heads 52a to 52c are also tilted so that the recording position is shifted by the base dot between heads of the same color.
Record eight dot lines constituting different scans @L2-L7. Each of these heads is driven simultaneously, recording a total of 21 dot lines simultaneously.

Since the head section 4B moves to the right by 8 dots, which is the width of the scanning line, every rotation of the rotating cylinder 41, the heads of type 7s are located on the same scanning line, and the 7s type heads are located within the 8x8 dot matrix. Up to seven types of ink droplets are ejected.

Here, recording of cyan ink and red ink starts from the cell at the top left of the dot matrix, and as the density level increases, the diameter of the ink dot increases and the pattern expands toward the cell at the bottom right. have. Yellow ink and blue ink expand from the bottom left to the top right, magenta ink and green ink expand from the bottom right to the top left, and black ink expands from the top right to the left. Additive color mixing is performed in the low density region of intermediate tones, and subtractive color mixing is performed in the high density region.

Since the ink droplets of each color are arranged at intervals of several dozen scanning lines, the ink droplets of the next color are deposited after the previously deposited ink droplets have impregnated the white paper 42. This helps prevent problems such as color mixing and surface running.

Furthermore, since each inkjet ejection head only needs to be fixed to a straight head portion, the structure is simpler than one arranged circumferentially, and the distance from the rotating cylinder 41 can be easily adjusted. The spacing between the juxtaposed heads corresponding to each color can be freely set according to the characteristics of the ink and blank paper materials, and the spacing can also be changed for each color instead of the spacing between the two heads. Therefore, for example, the distance between the inkjet ejection heads 46a and 47m may be wider than the distance between the inkjet ejection heads 51a and 52m, thereby making it possible to more completely prevent the above-mentioned trouble.

The head portion 48 is mounted on a pedestal 5 that moves parallel to the axial direction of the rotating cylinder 41 by a feed screw shaft 89 and a guide 40.
It is fixed at 8. This feed screw shaft 51 is rotated by a sub-scan pulse motor 54, and the sub-scan pulse motor 64 is driven by a drive pulse signal output from a central processing unit 84. This drive pulse signal is counted by a sub-scanning counter 65, and the counted value is displayed and sent to the central processing unit 84 as position information in the sub-scanning direction. Here, since the position of the inkjet ejection head in the sub-scanning direction is different for each color, it is necessary to detect the position of each scanning line to be drawn. For this purpose, the sub-scanning counter 56 to
62 is provided, and by counting the driving pulses after resetting each sub-scanning counter 66 to 62 to a preset value at the drawing position on the rotating cylinder 41, each color counted from the drawing position in the sub-scanning direction can be counted. The absolute position of each inkjet ejection head group can be detected.

During reproduction of both color axes, the main scanning pulse motor 44 and the sub-scanning pulse motor 54 are driven by drive pulses from the central processing unit 84, and each time the rotating cylinder 41 rotates once, the head section 48 moves for one scan. Move in the sub-scanning direction.

Since the positions of the inkjet ejection head groups of each color provided in the head unit 48 are detected by the sub-scanning counter 55, each inkjet ejection head group specifies the address of the next scanning line to be recorded, and simultaneously The eight color density signals of the seven scanning lines to be recorded are read from the storage device 86, and the central processing unit 84 converts the eight color density signals of each scanning line into seven color density signals, which correspond to the inkjet ejection head. The density signals of the selected colors are extracted and sequentially written into the nine-line buffer memory section 86 for each inkjet ejection head.

The density signal string of 91 scanning lines written in the line buffer memory section 86 is sent to the nine table memory section 87 for each inkjet ejection head, and the density signal string of each color is Eight dot signal rows are formed respectively. This dot signal train is read out using a position signal from the main scanning counter 46, and the head section 48 is aligned with respect to the blank paper 42.

These dot signal trains are sent to the head drive section 88, where they are converted into analog head drive signals to drive each of the 21 inkjet ejection heads. These inkjet ejection heads eject running ink droplets toward the white paper 42 in response to head drive signals, for example, 8 ink droplets for each color.
Write down the dot line i in the book. So cyan, magenta.

Seven different scan lines are recorded simultaneously with yellow, red, t, green, and black inks, and each scan line consists of eight dot lines.

The results of the image processing in the dual-axis information processing device 2 can be checked using a monitor television or the like, and adjustments can be made to obtain a desired reproduction rate while watching the image appearing on the monitor. Furthermore, the processed il is stored in the storage device 86.
i* Information signal is memorized and the same reproduction ii
You can achieve greatness.

The present invention having the above configuration is applicable to cyan and magenta.

In addition to the yellow ink, since the image is drawn using weather-resistant ink of at least intermediate colors of red and blue, the color reproducibility and weather resistance of intermediate colors are greatly improved. Furthermore, when expressing these intermediate color high-density areas using two color inks, problems such as K smearing in the nine colors of ink flow and wrinkles on the recording paper occur. Because it can be expressed, such inconveniences do not occur.

Furthermore, since the present invention forms density signals for red, real, etc. from density signals for cyan, magenta, and yellow, a conventional color scanner equipped with an eight-color separation optical system can be used as is. .

[Brief explanation of the drawing]

Fig. fs1 is a schematic diagram of an inkjet color printing apparatus implementing the present invention, Fig. 2 is a front view of the head section, Fig. 8 is an explanatory diagram showing the alignment state of the head section, and Fig. 4 is an explanatory diagram showing the dot matrix. It is a diagram. l...Digital color scanner 2...1tiiMy information processing station 8...Printer 1°1...Color original image 12...Main scanning pulse motor 18/work/main scanning counter 28--- , sub-scanning pulse motor 29, φ, sub-scanning counter 84, central processing unit 85, storage device 86φ, line buffer memory section 8, table memory section 88@Y, head drive section 42,・Confession Paper 48...Head section 44--Main scanning counter 64...Sub-scanning pulse motor 55--・Sub-scanning counter procedural amendment document dated 11th IX, 1986, Mr. Commissioner of the Japan Patent Office 1, Indication of the incident 1986 Patent Application No. 150581 3, Relationship with the amended case Patent applicant Address 210 Nakanuma, Minamiashigara City, Kanagawa Prefecture Name (5)
20) Fuji Photo Film Co., Ltd. 4. Voluntary action by the agent 6. ゛ Number of inventions increased by amendment 7, subject of amendment (1) Details of “Detailed explanation of the invention” in the specification (2) Item in the specification] -Brief description of the drawings” is amended as follows. (,1) In the 12th line of page 8, "because yellow has sub-absorption" is corrected to "because it includes sub-absorption". (2) Page 1O, line 16, “GP, Cp, J”
. Correct with BP, CP, and J. (3) Set "44...Main scan color/re" on the 9th line of page 26 to [44...]. (4) Between the 9th line and the 10th line of page 26, “4
5... Add "main scanning counter". that's all

Claims (2)

[Claims] (1) In an inkjet color printing method that draws a color image by controlling the ejection and amount of multiple color inks according to the density signals of cyan, magenta, and yellow, based on the density signals of cyan, magenta, and yellow, , removing and distributing at least the density signals of the main note component and the blue component to form at least cyan, magenta, yellow, red, and blue density signals, and controlling the inkjet ejection heads of each color with these density signals. An inkjet color printing method is characterized by drawing color images using five color inks. (2) In an inkjet color printing method that draws a color image by controlling the ejection amount of a plurality of color inks according to cyan, magenta, and yellow density signals, at least red At least cyan, magenta, yellow, red, and blue by removing and distributing the blue component and green component density signals. An inkjet color printing method characterized in that a color image is drawn using six color inks by forming green density signals and controlling inkjet output heads for each color using these density signals.