JPS59163970A - Color system - Google Patents

Abstract

PURPOSE:To reduce the image reproducing time by deciding that an input color signal is an image signal formed substantially by a specific color so as to select a prescribed sequence. CONSTITUTION:Reflected light of a light source irradiating an original is separated into three B, G, R colors through a filter and photodetected respectively by image pickup elements 14, 16 and 18. The three colors are processed for a prescribed processing at an image processing section 27 and inputted to a black signal deciding circuit 127. When no color signal exists in a UCR signal from a UCR processing circuit 11 in the circuit 127, an output of a gate 131 goes to an L level, the circuit 127 decides that the original is colored by black color only, the processing of B, G, R is omitted and a sequence selecting signal is outputted to complete the process by the black copying operation only. Then, since a full color signal processing step is omitted, the processing time is reduced and also black image quality is reproduced in excellent way.

Description

[Detailed description of the invention] The present invention is based on a color system.

A normal color copier or laser beam color printer that uses a photoreceptor creates a yellow or blue toner image on the photoreceptor and transfers it to transfer paper, then creates a magenta or green toner image and transfers it to the copy paper. , similarly for cyan or red, and similarly for black, repeat the same operation four times. Therefore, even if the original has only one color, operations for four colors are performed, resulting in a time loss of υ.

The present invention solves the above-mentioned drawbacks, and selects a predetermined sequence by determining that the input color signal is substantially an image signal composed of multiple specific colors. Once the black toner has been transferred from the photoreceptor to the copy paper, copying operations for other colors are prohibited and the image reproduction time is shortened. In addition, since the image processing is selectively controlled by determining the color, the painting room is not damaged. In addition, the black judgment is based on whether all the outputs after each color UOR process are at the peak level or not, or the maximum value of the input B, G, R signals (signals after γ conversion) or the Y, M, after masking correction, O.

It is determined whether the minimum value of the (B, G, R) signals exceeds a predetermined level. Furthermore, it is also possible to determine that the image is black and to turn off the dithering process so as not to impair the resolution. It is also possible to use the black determination to determine whether the black is a line drawing or one with gradation, and in the latter case, it is possible to perform dither processing using a matrix pattern different from the matrix pattern 2-.

FIG. 1 shows this embodiment. A document 1 is placed on a transparent plate 2 of a document table and fixed by a document mat 3. The photosensitive drum 24 and the transfer drum 53 rotate in the direction of the arrow to carry out the color process.

12 Hiro spectroscopic dichromators 2-114, 16.18 are CODs that sense spectral light and generate color signals B, G, and R. Scanning the original 1 by reciprocating the lamp 8 and mirrors 9 and 10, and outputting color signals B, G, and R from each COD at the same time,
It generates a Y signal for reproduction, then reciprocates again to output an M signal, repeats the above scanning four times to form Y, M, O, and BK times signals, controls the laser, and outputs an M signal on the drum 24. A latent image of each color is sequentially formed.

Each color is developed one after the other, and the transfer drum 53 is rotated four times to transfer it to the paper on top of it, thereby obtaining a full-color copy.

The optical system emits light from illumination lamps 5 and 6, and emits light from a reflecting mirror 7.
. Here, the light is split into blue wavelength light, green wavelength light, and red wavelength light. Of each decomposed light, the decomposed light of the true wavelength is filtered by the Buri filter 13.
The light passes through and is received by the solid-state image sensor 14. Similarly, the green wavelength light passes through the green filter 15 and is received by the solid-state image sensor 16. The red wavelength light passes through the red filter 17 and is received by the solid-state image sensor 18 . That is, the document 3 is further moved through the lens while maintaining the optical path length by a movable reflection mirror 9 that moves together with the illumination lamps 5 and 6, and a movable reflection mirror 10 that moves in the same direction at a moving speed of 9% of the moving reflection mirror 9. 11 and dichroic filter 12
8 solid-state image sensors for each color 14. ! , 16. The output of each solid-state image sensor 14°16.18 passes through an image processing section 27, which will be described later, and is irradiated from the semiconductor laser 21 to the polygon mirror 22 as light output. The polygon mirror 22 is a scanner motor 23
Since the photosensitive drum 24 is rotated more than once, the laser light is scanned perpendicularly to the direction of rotation of the photosensitive drum 24. A photo sensor 64 is located 11 meters before the laser beam starts scanning the drum, and when the laser beam hits this, it generates B and D signals.

The photosensitive drum 24 is negatively charged by a negative charger 25 that is supplied with a negative high voltage current from a high voltage power source 25. Next, when reaching the exposure section 26, the transparent plate 2 of the document table is exposed.
The upper original 1 is illuminated by illumination lamps 5 and 6, and is illuminated by movable reflecting mirrors 9 and 10, a lens 11, a dichroic filter 2,
Solid-state image sensor 14.16.18 by P/l/A filter 3, green filter 5, and red filter 17
The image output from the COD, which is formed into an image, is sent to the image processing circuit shown in FIG.
The laser beam passes through the γ correction unit 105, passes through the masking processing unit 109, and the UcR processing unit 119, and then is output from the group 1 processing unit 124, the multilevel processing unit 125, and the laser liner unit 126 to the laser 21. Photosensitive drum 24
is imaged. There, an electrostatic latent image is formed and enters four color developers 56, 57, 58, and 59. Here, three colors are separated in one exposure scan and each of the above processes is performed, but each TTOR
The outputs are selected sequentially for each scan of B, G, R, and black. When a one-color separation light signal in the image processing unit 27 is selected by a main body control signal (E signal for UOR), the corresponding developing device is selected. The developer selected thereupon performs powder development using a magnetic blade system, and the electrostatic latent image is visualized. Thereafter, it is negatively charged by a ghost lamp 40 for erasing the electrostatic latent image and a negative post electrode 41 supplied from the negative voltage power source 25, thereby erasing the electrostatic latent image.

Next, the paper feed rollers 46 and 47 rotate and the copy paper 48 is fed from the upper and lower cassettes 43 and 44 selected by the operating section 45, and the copy paper 48 is fed to the upper and lower rollers 49 and 5.
0 through the conveyance roller 51, the second registration roller 5
2 and is wound around the transfer drum 56. Thereupon, the toner on the photosensitive drum 24 is transferred onto the copy paper 48 by the transfer electrode 54. After the transfer has been completed, the photosensitive drum 25 removes the electricity from the copy paper 48 using the electricity removal electrode 55 supplied with a high voltage from the high voltage generator 25.

In the case of a normal color original, the above operation is repeated four times for four colors, and the transfer drum is rotated four times to superimpose each color. If black 1
In the case of an original with only colors, as described later, when it is detected that the original has only one color, black, after one optical movement is completed, processes such as G and H scanning, development, and transfer are jumped and the black image is created. Start copying operation. In the case of a color original, the operation time for four colors is required, but in the case of an original of only one color, black, the operation time can be shortened to two or one color. Twice Matahiro 4
The copy paper on which the rotational transfer has been completed is peeled off from the gripper 57, adsorbed onto the belt 59 by the conveyor 77, guided to the fixing section 60, fixed thereon, and sent out of the machine.

2 and 6 show image processing circuit diagrams.

The light from the original that is separated into three colors by the dichroic filter is CO
When irradiating D 14.16.18, its output is (3C
The signals are amplified by the D boards 10.1, 102, and 103, converted into A signals, and sent to the next shimming unit 104 in 8-bit parallel. When the amount of incident light on GOD is the same (when it is white)
In order to make the output data for each bit of COD equal, further correction is made to eliminate variations in 00D14, 16.18 for the three colors. Appropriate output is produced.

Next, in order to linearize the gradation between input and output by the γ correction unit 105, the optimum γ curve is set by the switch 10tS,
Select by switching the values of 107 and 108. In addition, 8
The reason for processing the upper 6 bits from bit is to perform processing in a significant level area.Next, the masking processing unit 109 processes each B, G
, R signals are simultaneously processed and the mixing ratio of each color component is changed to perform color correction. This calculation is performed using a thread number multiplication ROM and an addition/subtraction ROM. Switch 11 for the mixing ratio of each color
This is done by changing the value (number of threads) from 0 to 118.

Note that the reason why the calculated value is set to the upper 4 bits is to narrow it down to a significant area level.

Next, in the UCR processing unit 119, the logic of each comparator OOMF and each gate M1N is used to
The minimum value signal of is determined. Switch 1 to that minimum signal
The value obtained by multiplying the value of 20 by an arbitrary coefficient is set as the black level signal. Subtract that value from each color by each UOR. The signal is branched into two systems, one of which is sent to the dither processing unit 124 in response to select signals 121, 122 and 123 from the main body control section. In the dither processing unit 124, each color signal is a deep signal, for example, a 6-bit signal is compared using a table-referenced dither ROM and converted into a 1-bit digital signal to facilitate laser modulation. do. Next, R/W this signal
A multi-value processing unit 125 performs multi-value processing through the line memory, and a laser driver unit 126 drives the laser 21. In addition, the dither processing unit consists of a ROM with a low threshold level, a ROM with a high threshold level, and a ROM with a high threshold level.
M2, the input signal is simultaneously compared with these ROM outputs, the output from each comparator is stored in a memory and latched, and one pixel is divided into three equal parts. φ1 to φ for 1 pixel
It is divided into pulses with different widths of 3 and output in correspondence with RII of 14°, so that one pixel can be represented by four values.

On the other hand, a portion of the outputs of the B, G, and R UORROMs are input to the black signal determination circuit 127. What is input here are the top 4 BiTs out of 6 BjTs. This is because color signals with low density are ignored 6 BiT memory 1
28 has ``Usa'' stored at address 4 and ``F'' stored at all other addresses. For this reason, if there is no color signal in the UOR signal input to 127, F is outputted, which is latched by latch circuit 129 and input to hold circuit 130 in synchronization with the clock. This output is subjected to soft judgment by the control unit CPU and contributes to sequence control. 7 in Figure 4
This will be explained using a 0-chart.

On the other hand, Figure 1 shows a control circuit CPU that controls the copying operation.

The tallow is programmed into the microcomputer of the control unit CPU (69 in Figure 1), which first outputs the RFiSBT signal just before optical scanning for document scanning, and resets the outputs Q1 to Ct4t of the hold circuit 160. (Step 1).

If there is a color signal even once until the first optical scan is completed, the hold circuit 130 outputs FF, and as a result, the output 140 of the OR gate 131 becomes level ■.The control circuit CPU uses this signal for optical scanning. Immediately after completion (3), check 4), and if the H level signal is present, normal full color copying operation is performed (4).

If the gate 161 remains at the L level, it is determined that the original is all black, and a sequence selection signal is output to omit the B, G, and H processing and complete the process with only the black copying operation (6). Therefore, a sequence controller (not shown) moves only the black developing device to form and develop a latent image, and when the transfer drum rotates once, the gripper 57 is released and the transfer paper is discharged.

In this case, when scanning and developing are performed in the order of B, G, R, and black, the process rotation for G and H is omitted, so the processing time for two colors is sufficient.

Further, since the original is preliminarily scanned and the color can be determined at the end, the development time for one color of black is required.

In addition, if the process is to process 9 blacks, B, G, and H in the order, the formation of the black latent image has already been completed at the time of color judgment (at the end of scanning), so by blocking the subsequent processing, one color can be processed. The processing time is only 1 minute.

In the case of the type in which each color is reproduced on four photosensitive drums and the resist is taken on one sheet of paper and transferred sequentially, once the black process is completed, the paper feeding speed per sheet can be increased and the time can be shortened.

The present invention is effective even if the input signals B, G, and H in Fig. 2 are from a host computer;
, z can switch between the host and the OCD reader as necessary. In this case, if a monochrome command signal is prefixed to the position signal from the host, this can be determined and considered as a black image. Furthermore, even if the printer is of the 1-pixel, 4-dot type, it is effective in reducing time if there is a difference between the seven-color process and the one-color process. Furthermore, since the full-color signal processing step can be omitted, black image quality can be reproduced with good quality.

Further, even if it is determined that the input signal is a monochromatic image of any one of B, G, R, Y, M, and O other than black, sequence processing and signal processing can be omitted in the same way. This determination can be made by independently monitoring the outputs B, G, and R of the UCR and detecting that there is almost no output for any of them.

If a false tie is determined, it is determined that it is a character image, and the λ ther unit can be turned off and output without loss of resolution. In this case, in order to reproduce some intermediate tones by using the pulse width modulation of the laser drive signal using the four values described above, static threshold values (6 levels) are set by the signals a1 to a3 for the buzzers ROMI to 3, and the above pulses are set. Width modulation or brightness modulation is possible. Also, by determining the output from the hold circuit 130 for each line and applying a reset, it is possible to determine black for each line, and to sequentially control the selection of signal processing such as a buzzer. . It is also possible to judge and determine every few pixels, and to perform the above-mentioned partial selection control with accurate synchronization.

As described above, in the present invention, by determining a specific color such as black in a color system such as a full-color copying machine, the copying time can be reduced from about % to K for a monochrome original. Further, signal processing can be performed to improve the resolution of characters and the like. Since unnecessary color signal processing is not performed, the quality of a specific color does not deteriorate.

In addition, unnecessary charging, laser irradiation, development, and
Since processes such as transfer and printing are prohibited, unnecessary fatigue is not caused and the life of the machine can be extended.

[Brief explanation of the drawing]

Figure 4 is a flowchart of color signal determination.

Claims (1)

[Claims] It has a plurality of color signal input means, a means for processing the plurality of color signals and outputting a color reproduction signal, and a means for determining that the input signal is substantially an image signal formed by a plurality of specific colors. , a color system characterized in that a predetermined reproduction sequence operation is selected based on the determination output.