JPH0681235B2 - Copying device - Google Patents

Description

The present invention relates to a copying apparatus having a reading unit that converts a target image into image signals of a plurality of color components by one scan and reads the image signals.

<Prior Art> An apparatus for processing image data having color components and performing color printing has been known.

Among these apparatuses, a frame-sequential color image forming apparatus, for example, an ordinary color copying machine or a laser beam color printer using a photoconductor, first forms a yellow or blue toner image on the photoconductor and then forms it on a copy paper. It was configured to transfer, then form a magenta or green toner image, transfer to copy paper, and repeat the same operations for cyan or red, and then black.

Also in such a frame-sequential color image forming apparatus, there is known an apparatus which can be set to a monochromatic copy mode in which only one color image is formed by a manual operation of a user.

<Problems to be Solved by the Invention> However, when a user of a color image forming apparatus tries to copy a single-color original document without setting the single-color copy mode, even if the original document has only one color, as described above. In this case, it is necessary to perform image formation of four colors in a frame sequential manner.
By performing the color image forming operation, there is a risk that the color that should not be originally imaged is mistakenly formed even slightly and the image quality is deteriorated.

Further, even if the original has only one color as described above, a problem occurs in terms of the durability of the apparatus by performing frame sequential image formation for four colors.

In view of the above points, the present invention has an object to provide a copying apparatus which has improved operability and does not deteriorate image quality, and has improved durability.

In order to achieve such an object, the copying apparatus of the present invention has a reading means (in the embodiment, FIGS. 1 to 5 for details, see FIG. 1) for converting a target image into an image signal of a plurality of color components and reading it by one scanning. (Corresponding to CCDs 14, 16, and 18), processing means for sequentially outputting a plurality of recording color component signals corresponding to each of a plurality of developers having different color components from the image signals of the plurality of color components from the reading means ( Similarly, UC in Fig. 2
R processing unit 119), forming means for sequentially forming one screen image of each color component of each of the plurality of developers based on the recording color signal from the processing means (also the transfer drum 53 in FIG. Discriminating means for discriminating whether or not the target image has a predetermined color component from the image signals of the plural color components from the reading means (drum 24, developing devices 36 to 39, etc.) (also the single color discriminating circuit in FIG. 2). 127), control means for controlling the forming means so as to omit image formation by the developer of the predetermined color component in accordance with the discrimination by the discriminating means (first illustrated control for executing the flowchart of FIG. 4 as well) Circuit 69), and the reading unit performs a reading scan for the determination by the determining unit before the reading scan for the image formation by the forming unit.

<Example> FIG. 1 shows the present example. The original 1 is placed on the transparent plate 2 of the original table and fixed by the original mat 3. Photosensitive drum
24, the transfer drum 53 rotates in the direction of the arrow to execute the color process. Reference numeral 12 is a spectroscopic dichroic mirror, and reference numerals 14, 16 and 18 are CCDs that sense the spectrum and generate color signals B, G, and R, respectively. The lamp 8 and mirrors 9 and 10 are reciprocally moved to scan the original 1 and simultaneously
The color signals B, G, R are output from the CCD, the reproduction Y signal is generated, and then the reciprocating motion is repeated to output the M signal, and the above scanning is repeated 4 times to form the Y, M, C, BK signals. Then, the laser is controlled to sequentially form each color latent image on the drum 24. Each color is sequentially developed, the transfer drum 53 is rotated four times, and repeatedly transferred to the paper on it to obtain a full-color copy.

The optical system emits light from the illumination lamps 5 and 6, and is combined with the light from the reflecting mirrors 7 and 8 to illuminate the original, and the reflected light is reflected by the moving reflecting mirrors 9 and 10 and the lens 11 Pass through the 12 dichro filters. Here, it is split into light of blue wavelength, light of green wavelength, and light of red wavelength. The decomposed light of the blue wavelength of each decomposed light passes through the blue filter 13 and is received by the solid-state imaging device 14. Similarly, light of a green wavelength passes through the clean filter 15 and is received by the solid-state image sensor 16.
The light of the red wavelength passes through the red filter 17 and is received by the solid-state imaging device 18. That is, the original 3 is moved by the moving reflecting mirror 9 which moves integrally with the illumination lamps 5 and 6 and the moving reflecting mirror 10 which moves at the half speed of the moving reflecting mirror 9 and moves in the same direction. Lens 11 while maintaining
And the solid-state image sensor 14, 18, for each color through the dichro filter 12.
Imaged at 16. The output of each of the solid-state image pickup devices 14, 16 and 18 is applied as a light output from the semiconductor laser 21 to the polygon mirror 22 via an image processing unit 27 described later. Since the polygon mirror 22 is rotated by the scanner motor 23, laser light is scanned perpendicularly to the rotation direction of the photosensitive drum 24. Further, there is a photo sensor 64 at a position 1 mm before the laser beam starts scanning on the drum, and when the laser beam hits the photo sensor 64, B and D signals are generated.

The photosensitive drum 24 is negatively charged by the negative charger 25, which is supplied with a negative high voltage current from the high voltage power supply 25. Then, when it reaches the exposure unit 26, the original 1 on the transparent plate 2 of the original table is illuminated by the illumination lamps 5 and 6, and the moving reflecting mirrors 9 and 10 are moved.
And lens 11, dichro filter 12, blue filter 1
3, the image output from the CCD imaged on the solid-state image sensor 14, 16, 18 by the green filter 15 and the red filter 17,
By the image processing circuit of FIG. 2, each color passes through the shading unit 104, the γ correction unit 105, the masking processing unit 109, the UCR processing unit 119, the dither processing unit 124, the multi-value processing unit 125, The laser light is output from the laser driver unit 126 to the laser 21, and the laser light is focused on the photosensitive drum 24. There, an electrostatic latent image is formed and enters the four-color developing devices 36, 37, 38, 39. Here, the three colors are separated by one exposure scan, and each of the above processes is performed.
The output of R is sequentially selected for each of B, G, R, and black scan. When the one-color separation optical signal in the image processing unit 27 is selected by the main body control signal (E signal for UCR), the developing device corresponding to the selected one is selected. The developing device selected there is carried out by powder development using a magnetic blade method to visualize the electrostatic latent image. After that, the ghost miniature lamp 40 for erasing the electrostatic latent image and the negative post electrode 41 supplied from the negative voltage power supply 25 negatively charge the electrostatic latent image.

Next, the copy paper 48 sent by rotating the paper feed rollers 46, 47 from the cassette selected from the upper and lower cassettes 43, 44 from the operation unit 45 passes through the first registration roller, the lower 49, 50, It is wound around the transfer drum 53 from the transport roller 51 through the second registration roller 52. Therefore, the toner on the photosensitive drum 24 is transferred to the copy paper 48 by the transfer electrode 54. After the transfer, the photosensitive drum 25 removes electricity from the copy paper 48 by the electricity removing 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, if it is detected that the original has only one black color at the time when one optical movement is completed as described later.
The G, R scan, development, and transfer processes are jumped, and the black image copying operation is started. In other words, four color operation times are required for color originals, but 2 for single black originals.
The operating time for one color or one color can be shortened. The copy paper, which has been transferred twice or four times, is peeled off from the gripper 57, adsorbed on the belt 59 by the transport fan 58, guided to the fixing section 60, fixed, and then sent out of the machine.

2 and 3 show image processing circuit diagrams. The light of the original separated into three colors from the dichro filter is CCD14,16,18
When the light is emitted, its output is amplified by the CCD substrates 101, 102 and 103, A / D converted, and sent to the next shading unit 104 in 8 bit parallel. When the incident light quantity of the CCD is the same (white), the output data for each bit of the CCD is the same, and further correction is made so that the variations of the CCDs 14, 16 and 18 for the three colors are eliminated. Since it has a RAM configuration, the data or address is properly output.

Next, an optimum γ curve is selected by switching the values of the switches 106, 107 and 108 in order to linearize the gradation property between the input and output by the γ correction unit 105. Incidentally, from 8 bits to the top 6
The bit processing is used for processing in a significant level area.

Next, the masking unit 109 performs arithmetic processing on each B, G, R signal at the same time to change the mixing ratio of each color component to perform color correction. This calculation is performed by the coefficient multiplication ROM and the addition / subtraction ROM. The mixing ratio of each color is performed by switching the values (coefficients) of the switches 110 to 118. Incidentally, the reason that the calculated value is set to the upper 4 bits is that it is limited to a significant area level.

Next, in the UCR processing unit 119, the minimum value signals of B, G, and R are discriminated by the logic of each comparator COMP and each gate MiN. A value obtained by multiplying the minimum value signal by an arbitrary coefficient according to the value of the switch 120 is used as a black level signal. That value each
Subtract from each color by UCR. The signal is branched into two systems, and one of them is sent to the dither processing unit 124 by a select signal 121, 122, 123 from the main body control unit. In the dither processing unit 124, each color signal is a deep signal, and for example, a 6BiT signal is used as a table-referenced dither ROM.
Is used to make a 1-bit digital signal of 1 or 0 so that the laser can be easily modulated. Then this signal
The laser 21 is driven by the laser driver unit 126, which is multivalued by the multivalued processing unit 125 through the R / W line memory.
The dither processing unit has ROM ₁ in which low threshold levels are arranged, ROM ₃ in high arrangement, and ROM ₂ in the middle.The input signal is compared with these ROM outputs at the same time, and the output from each comparator is compared. Put in memory, latch, and divide 1 pixel into 3 equal parts. In other words, one pixel is divided by pulses having different widths of φ ₁ to φ ₃ , and each pixel is output corresponding to ROM ₁ to ₃ , whereby one pixel can be represented by four values.

On the other hand, a part of the ROM output of each UCR of B, G, and R is input to the monochromatic signal determination circuit 127. What is input here is the upper 4 BiT of the 6 BiT. This is because the color signal with little density is ignored, and 6BiT may be left as it is.

The OR gate 128 outputs L if there is no color signal in the UCR signal input to 127, and outputs H if there is, and the latch circuit 12
It latches at 9 and is input to the hold circuit 130 in synchronization with the clock. This output is software judged by the control unit CPU and contributes to sequence control. An explanation will be given using the flow chart of FIG.

This flow is programmed in the microcomputer of the control unit CPU (FIG. 69 in FIG. 1). First, the RESET signal is output immediately before the optical scan for document scanning, and the output of the hold circuit 130 is output.
The Q ₁ ~Q ₄ to reset (step 200). Next, an optical prescan is performed to expose the document (step 201).

Optical spare skiyan (step 202), 1 by then
If there is a color signal even once, the hold circuit 130 outputs the H signal to the output terminal corresponding to the color signal. For example, in the case of a B-color original, Q ₁ is H and Q _{2 to} Q ₄ are L.

The control circuit (Fig. 1 69) checks this signal immediately before the start of the optical scan for reproduction of each color (step 20).
3) If the signal is H, reproduction processing for that color is performed (step 204). For example, if the original is blue B, green G,
A sequence selection signal is output so that the reproduction processing of the red R and black is omitted and only the B reproduction processing is performed. Therefore, the sequence controller (not shown) makes only the blue developing device movable to form a blue latent image and develops the latent image.
1 for transferring the blue image to the transfer paper of the transfer drum
When the rotation is completed, the gripper 57 is released and the transfer paper is ejected.

In this case, when B, G, R and black are processed in the order of scanning and development, the process rotation for G, R and black can be omitted, and the processing time for one color is sufficient.

In this case, the main scan may be performed in steps 201 and 202, and when the scan is completed, the formation of the blue latent image is completed when the blue monochromatic image is found. I need time.

In the case of only two colors, for example, in the case of only B and G originals, the reproduction processing of the red R and black is similarly omitted.

Step because the Q ₁ ~Q ₄ are all H in the case of Bull color
All of 204 to 207 will be executed.

In the case of the type in which each color is reproduced on four photosensitive drums and the resist is sequentially transferred onto one sheet of paper, the paper feeding speed can be increased and the time can be shortened after finishing the process of the specific color.

Note that the present invention is effective even if the input signals B, G, and R in FIG. 2 are from the host computer, and the host and the CCD reader are connected at the connection points of X, Y, and Z as necessary. Can be switched. In this case, when a monochrome command signal is added to the head of the transmission signal from the host, this can be judged and regarded as a black image. Further, even in the case of a 1-pixel 4-dot type printer, it is effective in shortening the time when there is a difference between the monochrome process and the full-color process. Further, since the full-color signal processing step can be omitted, the black image quality can be reproduced well.

When a monochrome image (one color for each of B, G, R, black, etc.) is determined, it can be recognized as a character image and the dither unit can be output in an output state without impairing the resolution. In this case, 4
Some order to reproduce halftones Sutateitsuku a Ikichi a (3 levels) and excisional the signal a ₁ ~a ₃ for design ROM ₁ ~ ₃ the pulse width modulation by using pulse width modulation of the laser drive signal by a value Alternatively, the brightness can be modulated.

Further, by judging the output from the hold circuit 130 for each line and applying the reset, it is possible to perform the monochromatic judgment for each line and to selectively control signal processing such as successive dither. Further, it is possible to make a determination for every several pixels, so that the synchronization can be accurately performed and the partial selection control described above can be performed.

FIG. 5 is a circuit diagram for inserting characters, numbers and the like into the above color image.

200 is a code generating means for generating characters and numerical values as code data, M ₁ is a buffer memory for storing the code data at the same time as the code is generated, ADC ₁ is an address counter for controlling the address for writing and reading the memory,
CG is a character according to the code data read from the memory M ₁ ,
A well-known character generator that outputs a numerical value as dot pattern image data, M ₂ is a buffer memory that stores the dot data from the CG at the same time as the output, and stores one pixel of the image data to correspond to one dot from the CG. That is, a dot pattern for a plurality of characters and numbers is stored with each character and each numerical value having a predetermined interval similar to that of the reproduced image. The ADC ₂ is an address counter that controls the address for writing and reading the memory M ₂ , and it determines the read start timing in synchronism with the progress of color image data processing. You can determine the character composition position in. 201 is a signal input source for presetting the timing. When the image processing shown in FIG. 2 reaches the preset coordinates X, Y by 201, the reading from the memory M ₂ is started and the color reproduction corresponding to the above position after dither processing is performed. The character output is synthesized from the output.

Reference numeral 205 denotes a gate which outputs the CG output as H (black) when the output of the comparator 206 is L (white, halftone), and 204 outputs L (white) when the output of the comparator is H (black). It is an inverter.
The comparator 206 outputs H when the output A of the black component in FIG. 2 is above a certain level L _{1 and} L when it is below the level L ₁ . Accordingly, when the image is a dark background color, the signal of the above level is output from B in order to clear the character image from the CG from the background color and to make the character image black when the tone is light. The signal from B is input to the OR gate 210 in FIG. 3 and is combined with the image data after dither processing. In this case, since the inserted characters are not dithered, the resolution is not impaired.

The R / signal is a write / read signal, and the read signal of the memory M ₂ is synchronized with the black process (black scan,
Black process), which is output to form black as characters. If the color image is a monochromatic image of blue and if it is desired to insert characters by red, the red processing step is further executed and a read signal for outputting the B signal only during that step is given to the memory M ₂ in synchronization with the red processing. To do. The address counter ADC ₂ uses the image data processing dot (CL) to determine the read start timing of the memory M _2.
K) and the line are counted, and when the count value reaches the preset X, Y by 201, the reading of the memory M ₂ is started in synchronization with the clock CLK. Dot counting starts counting bit by line end signal,
The line count starts from the start of color data processing with a beam detection signal in the laser scanner indicating the end of one line scan or a dot count end signal for one line.

When the code "1984" is stored in the memory M ₁ by the key or transmission line attached to the copying machine of FIG. 1 as shown in FIG. 6,
The CG converts it into a dot pattern and stores it in the memory M ₂ . After that, the above-mentioned color data processing becomes possible (in this example, scanning of the original by the optical system becomes possible.
It is prohibited until then unless there is a command input that there is no inserted data. ) When the color data processing is started and the preset coordinates X and Y of 201 are reached in the black scan process, the reading of the memory M ₂ is started and the B signal of the character is CLed.
It is sequentially output in synchronism with K, and is composited as shown in FIG. 3 to form a latent image of black characters on the drum, and is transferred and composited to the previous color image to obtain a color print with characters. If necessary, other color characters such as red and blue can be inserted as described above.

However, when a character is added to a position where a part of a dark color (black) is used as a background, the background is automatically determined from the signal A and a white character signal is formed as the signal B as described above. Output. This procedure has a circuit configuration with accurate synchronization so that it can be achieved in real time for color image processing.
The preset data 201 can be the key of the copying machine shown in FIG. 1 or the transmitted code data. It may be a memory ROM that stores the format 200.

By the way, when the background color is repeated in a short range like a stripe pattern, it may be unsightly to process the white color accordingly. To eliminate the inconvenience, a delay circuit is provided at point W in FIG. The whitening can be performed only when the base of the predetermined range is dark.

By the way, when all characters are to be added with a white outline, the read timing of the memory M ₂ can be determined so that the processing can be performed in the color image processing step at that time.

As described above, in this embodiment, since the reproduction mode of the insertion data can be selected, the insertion character can be made remarkable, and in the color system such as a color copying machine, a specific color such as black is judged to make the insertion character black. By doing so, the copying time can be shortened from about 1/2 to 1/4 for a black original document. In addition, it is possible to perform signal processing that enhances the resolution of characters and inserted characters in the image. Since unnecessary color signal processing is not performed, the quality of the specific color does not deteriorate.

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

<Effects of the Invention> As described above, according to the present invention, it is possible to determine whether or not a document has a predetermined color component before the reading scanning for image formation by the reading unit. Before the image forming operation, the developer necessary for the image formation can be surely determined, and when the original does not have the predetermined color component, the image formation by the developer is omitted. By
It is possible to further improve the durability of the device without fear of degrading the image quality.

[Brief description of drawings]

FIG. 1 is a sectional view of a color copying machine to which the present invention can be applied, FIGS. 2, 3, and 5 are circuit diagrams of an image processing unit, and FIG. 4 is a flow chart diagram for determining a color signal. FIG. 6 is an explanatory diagram of the reproduced image, and shows 27 ... Image unit 127 ... Black determination circuit.

Claims (1)

[Claims] 1. A reading unit that converts a target image into an image signal of a plurality of color components by one scanning and reads the image signal, and a plurality of developers having different color components from the image signals of the plurality of color components from the reading unit. Processing means for sequentially outputting a plurality of recording color component signals corresponding to each of them, and sequentially forming one screen image of each color component of the plurality of developers based on the recording color component signals from the processing means. Forming means, judging means for judging whether or not the target image has a predetermined color component from image signals of a plurality of color components from the reading means, and visualizing the predetermined color component according to the judgment of the judging means. And a control unit that controls the forming unit so as to omit the image formation by the agent, and the reading unit is provided for the determination by the determination unit before the reading scan for the image formation by the forming unit. Read scan Copying apparatus according to claim and.