JPS63269685A - Image processor - Google Patents

Abstract

PURPOSE:To improve the processing speed of an image processor and to reduce the cost of its processing circuit, by processing plural picture data to be printed on the same transfer paper by means of the same circuit in line sequence. CONSTITUTION:The rotation of a polygon motor is kept at a high speed in conformity to a data processing speed. In other words, writing with a laser beam is switched in the order of Bk (black) C (cyan) M (magenta) Y (yellow) k.... When such writing procedure is applied, the copying speed of an A-4 size paper becomes (60X25)/(210+40)=6(copies/min), if the speed is droped to 1/4 and the line speed is set at 25 mm/sec, and then, a paper interval is set at 40 mm. The copying speed of A-3 size paper becomes about 3(copies/min) which is twice as fast as the copying speed of a drum system. Therefore, such advantages that thick paper can be used, a full-page image can be copied, and can be used practically and, moreover, the line speed of 25 mm/sec produces less noise and consumes less power. In addition, copying operations at the line speed of 25 mm/sec can improve the reliability in scattering of toner, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to an image processing apparatus such as a color copying machine or a color facsimile.

(Prior Art) Conventionally, two methods have been considered for digital color copying machines and color facsimile machines that process color images using digital technology. The following explanation will be given using a color copying machine as an example, but the same applies to a color facsimile. FIG. 3 is a one-drum color copying machine, FIG. 4 is a block diagram of its electrical equipment, and FIG. 5 is a four-drum color copying machine, and FIG. 6 is a block diagram of its electrical equipment.

In the one-drum system, as shown in the block diagram of Fig. 4, eight solid-state image sensors CCD7r, 7g, and 7b are arranged in red (hereinafter referred to as R), green (hereinafter referred to as G), and blue (hereinafter referred to as B). It reads the information of three wavelengths, performs processing such as γ (gamma) correction, color correction (masking), and UCR (undercolor removal), performs gradation processing for output to a laser printer, drives the laser, and copies. Get the print.

In this case, the same document is scanned four times, and the same process is repeated four times (repeat, but the last laser driver part is yellow (hereinafter referred to as Y), magenta (hereinafter referred to as M), cyan (hereinafter referred to as C). ), black (hereinafter referred to as Bk) is selected once, and control is performed so that a four-color print is obtained as a result.Therefore, the transfer drum wrapped with transfer paper rotates four times. There is a need.

However, since only one set of expensive parts such as a laser driver and a laser optical system is required, the cost can be made relatively low.

On the other hand, the 4-drum system shown in Figure 5 is the same as the 1-drum system until gradation processing is performed, but the laser optical system,
Since there are four sets of photoreceptors, a buffer memory for alignment and four sets of laser optical systems are required, making it more expensive than the one-drum system.

However, since the four colors are transferred while the transfer paper passes over the belt, the copying speed increases. In addition, since there is no need to wrap it around the transfer drum, it is possible to produce a full-page image that can be used without a paper clamp, and there are other benefits such as the ability to use thick paper such as postcards.

Here, the speeds of the 1-drum method and the 4-drum method will be compared. It is possible to copy up to A3 size, and the data processing speed is ranked second in IOMH, with a line speed of 10
In the case of 0 mm/sec, calculate the copy speed for A4 size paper.

■In the case of a drum, the transfer drum around which the A3 size is wrapped must have a diameter of at least 160 mm. Therefore, the number of copies per unit time is A4 and A3 size (80secX 100mm/5ee)/(4X y
r
py/m1n) Approximately 10 for A3 size (copy
/m1n).

(Purpose) The purpose of the present invention is to increase the speed (and reduce the cost of processing circuits) in image processing devices such as digital color copying machines and color facsimiles that separate color images into pixels and record them using digital technology. shall be.

(Structure) The present invention realizes cost reduction of a processing circuit using a four-drum system. The basic idea of the present invention is to reduce the line speed to 1/4 and use a common circuit where RGB or BkCMY processing can be performed line-sequentially.

Therefore, the speed of data processing is not reduced. First, only one solid-state image sensor COD is used, and RGB lines are sequentially input by switching filters. Expensive CCD elements and A/
D conle <- can be reduced. LD also in the output section
Commonize the circuits and drivers that control the light emission time and make it multivalued.

The configuration of the present invention will be described below based on a color copying machine as an embodiment.

FIG. L2 shows an embodiment of the present invention. 3. Compared to the conventional devices shown in FIGS. 1, 4, 5, and 6, there is a difference in the image input section and output section.

FIG. 1 is a configuration diagram of a mechanism section of an embodiment of the present invention. FIG. 2 shows a block diagram of the electrical components of the device shown in FIG. First, referring to FIG. 1, a document is placed on a contact glass 1 and illuminated by a document illumination lamp 2, and the reflected light is reflected from a movable first mirror 3, second mirror 4, and third mirror 5. After passing through the imaging lens 6, the light is separated into three wavelength ranges of light, R1G and B, by a filter 50 which can be switched by moving or the like.

A portion of the neutral filter in the filter 50 is used when making black and white copies, and in this case, the filters are not switched, so that the copying speed can be four times faster than when making color copies. Printers also quadrupled their line speeds,
If you laser write only Bk, it will be 20 (copy/
m1n)/A4 black and white copy. In other words, line speed switching, data selector, and filter switching are performed in black-and-white mode and color mode.

This filter may use a filter in which each part of a disc is color-coded, and the filter may be rotated to perform color separation.

The light separated by the filter 50 enters the CCD 7, which is a solid-state image sensor. The lamp 2 and the first mirror 3 are mounted on a first carriage (not shown), the second mirror 4 and the third mirror 5 are mounted on a second carriage (not shown), and the second carriage is 1/1/2 of the first carriage. By moving at a speed of 2, the optical path length from the original to the CCD is kept constant, and the first and second carriages scan from right to left when reading the original image.

The output of the CCD 7 is converted from analog to digital, subjected to necessary processing in an image processing unit, and converted into binary signals of Bk, Y, M, and C, which are recording color information. 2
The value signal is input to the laser driver 112, and the laser driver drives the semiconductor laser 113.
A laser beam modulated with a recording color signal (binarized signal) is emitted.

As shown in FIG. 7, the laser beam emitted from the semiconductor laser 43 is reflected by the rotating polygon mirror 13, and the fθ lens 14
After that, it is reflected by the fourth mirror 15 and the fifth mirror 16,
The image is formed on a photoreceptor drum 18 through a polygonal mirror face tilt correction cylindrical lens 17.

The rotating polygon mirror 13 is eccentrically attached to the rotating shaft of a polygon mirror drive motor 41, and each motor rotates at a constant speed to rotationally drive the polygon mirror at a constant speed. As the polygon mirror rotates, the laser beam is scanned in a direction perpendicular to the rotation direction (clockwise) of the photoreceptor drum, that is, in a direction along the drum axis.

A sensor 51 made of a photoelectric conversion element is disposed at a position that receives laser light at one end of laser scanning (double-dashed line) in the direction along the axis of the photoreceptor drum 18, and this sensor 51 detects the laser light. However, the starting point of one line scan is detected at the time when this changes from detection to non-detection. That is, the laser light detection signal (pulse) from the sensor 51 is processed as a line synchronization pulse for laser scanning.

Also, referring to FIG. 1, the surface of the photoreceptor drum is uniformly charged by a charger 19. As shown in FIG.

When a laser beam modulated by a recording signal is irradiated onto the uniformly charged surface of the photoreceptor, the charge on the photoreceptor flows to the equipment ground of the drum body and disappears due to a photoconductive phenomenon. Here, the laser is not turned on in areas where the original density is high, and the laser is turned on in areas where the original density is low. As a result, an electrostatic latent image is formed on the surface of the photoreceptor drum 18 in accordance with the density of the original. This electrostatic latent image is transferred to a Bk developing unit, a Y developing unit, an M developing unit, and a C developing unit, respectively.
The toner images are developed by a developing unit to form BkXY, M, and C toner images on the surface of the photoreceptor drum, respectively.

The toner in the developing unit is positively charged by stirring, the developing unit is biased by a bias generator (not shown), and the toner adheres to the area where the surface potential of the photoreceptor is higher than the developing bias, forming a toner image corresponding to the original. .

On the other hand, the recording paper 26 stored in the transfer paper cassette 22 is fed by the paper feeding operation of the delivery roller 27, and is sent to the transfer belt 25 by the registration roller 24 at a predetermined timing. As the transfer belt 25 moves, the recording paper placed on the transfer belt 25 sequentially passes under the photoreceptor drums, and while passing through each photoreceptor drum, the transfer charge +29bks 29ys 29m is charged at the bottom of the transfer belt.
129C, the Bk, Y, M, and C toner images are sequentially transferred onto the recording paper.

The transferred recording paper is then sent to a thermal fixing unit 36, where the toner is fixed to the recording paper, and the recording paper is discharged to a paper output tray. On the other hand, residual toner on the photoreceptor surface after transfer is
It is removed by the cleaner unit 21.

Next, the operation timing of the main parts of the copying mechanism will be explained with reference to the time chart shown in FIG. FIG. 8 shows the case when two identical full-color copies are made. The modulation energization of the laser 43bk based on the recording signal is started at almost the same timing as the start of the exposure scan of the first carriage, and the lasers 43Y, 43m, and 43c each move from the photoreceptor drum 44bk to 44 ys 44 rrh 44
Travel time T of the transfer belt 25 for a distance c,! /s
Modulation energization is started with a delay of T m% T c.

Transfer charger 29bk129ys 29m529
c are respectively laser 43 b ks 43 yz 4
It is energized after a delay of a predetermined time (time for the laser irradiation position on the photosensitive drum to reach the transfer charger) from the start of modulation energization at 3m143c.

See Figure 2. The image processing unit converts the three-color image signals read by the CCD 7 into K, Y, M, and C recording signals necessary for recording.

The Bk recording signal remains as it is, and the YlM and C recording signals are
After storing each recording color gradation data that is the source of each in the buffer memory, the delay time T y shown in FIG.
+ T After m and Tc, it is read out and converted into a recording signal, and then sent to the laser driver 1 through the data selector 110.
Give to 12. Note that in the copying machine mode, the image processing unit is given three color signals from the CCD 7 as described above, but in the graphics mode, three color signals are given from outside the copying machine through the external interface 117.

The shading correction circuit 101 of the image processing unit includes:
The color gradation data obtained by A/D converting the output signal of the CCD 7 into 8 bits is corrected for optical illuminance unevenness, variations in sensitivity of the internal unit elements of the C0D 7, etc., to create read color gradation data.

The multiplexer 102 is a multiplexer that selectively outputs either the output gradation data of the line buffer or the output gradation data of the interface circuit 117.

The γ correction circuit 103 that receives the output (color gradation data) of the multiplexer 102 changes the gradation (input gradation data) according to the characteristics of the photoreceptor, and also changes the gradation according to the characteristics of the photoconductor. The gradation is changed and the input 8-bit data is changed to the output 6-bit data. In this case, since the output is 6 bits, data representing one of 64 gradations is output. 6 showing the respective gradations of R, G and B output from the γ correction circuit 103
Bit three-color gradation data is used for complementary color generation and black separation circuit 104.
given to.

The configuration of the complementary color generation and black separation circuit 104 is shown in FIG. Complementary color generation is the renaming of each color read signal to the recorded color signal, and R gradation data is changed to C gradation data, 0
The gradation data is converted (read) into M gradation data, and the 8 gradation data is converted into 7 gradation data. The C, M and 7 gradation data are supplied as they are to the averaging data compression circuit 105.

If all of these gradation data indicate high density, record it as black.) Therefore, with a digital comparator, C2M
and 7 gradation data are each compared with reference value data set by the threshold value setting switch 104sh. The digital comparators 104c, 104m, and 104y each compare 8-bit data, and input data (input data) obtained by adding the upper 2 bits of the L level to the 6 bits of the gradation data, and Comparing with 8-bit data (reference value data) in which the upper 3 bits are set to L level and the 2nd to 4th lower bits are reference value data set by the threshold setting switch 104sh,
If the input data is less than or equal to the reference value data, L is given to the Nant gate 104, and if it exceeds it, H is given to the Nant gate 104.

The Nant gate 104a outputs L (black) when all the comparators are giving an L signal, and outputs H (white) when any one is giving an H signal, and provides the output to the data selector 110. To explain this in more detail, the gradation data input to the comparator is 6-bit data in hexadecimal notation, and ranges from O to 3FH.
When writing black output, the configuration is such that L represents black and H represents white. Therefore, the MSB side 2 bits (Q6.7) of the 8-bit input data are input to L, and the C, M, and Y gradation data are input to the lower 6 bits (QO to 5), respectively.

On the comparison data side, the comparison level can be set to 7 levels.
It uses a rotary set of dip switches. Furthermore, since it is a black level setting, if too many white colors are included in the black color, halftones (gray) can be recorded as black and the resolution can be increased, but on the other hand, heat is generated more often due to color balance.
I don't like it. Therefore, I set the 5.6 bit to be able to set up to the middle level in 7 steps, and since there is no need to set it too precisely, I set the 1 bit on the LSB side to L and set the dip switch to the middle 3 bits (Pi to 3). 1
Setting values from 04sh are input.

Now, if the dip switch 104sh is set to , the reference value is , and when the C, M, and Y data are all below this value, that is, between O and 3 in decimal, the comparator output is and set the Bk output to L (black). Here, the setting dip switch 104sh is commonly used for comparison settings of C9M and Y, but by using three sets, it is possible to set the setting range for each color to the lowest and highest settings. It is also possible to output a specific color in a black pattern with good resolution by setting it using the switch.

The averaging data compression circuit 105 of the image processing unit has 1
An image having 6-bit gradation data is averaged over 8×8 image data and output as 6-bit gradation data. In this example, it is assumed that the size of the input image and the output image are the same, and the input data (COD
A/D converts the read value from ) to 8-bit data, and converts it to 6-bit data by γ correction.
The output data to the laser driver is the laser on/off (
1 bit) data. 6 depending on input 6-bit data
It is possible to separate four gradations of density.

The dither method and density pattern method are well known for output density reproduction. Generally, an 8×8 matrix is used to express 64 gradations using the density pattern method. Therefore, the density of 8 x 8 pixels of input data is averaged, and the output 8 x 8 matrix (density pattern conversion in the gradation processing circuit 109)
It is necessary to correspond to Furthermore, this averaging compresses the data amount and processing speed to 1/64, reducing the data capacity for storage and the cost of the hardware unit. It is conceivable to increase the size of the pixels for input reading by 8 x 8 times the size of the output, but this is not adopted in the device of this embodiment because, as mentioned above, we do not want to reduce the resolution of black parts (normal characters). .

FIG. 10 shows the configuration of the averaging data compression circuit 105,
FIG. 11 shows the operation timing of the circuit 105. The data to be averaged are 8 pixels in the sub-scanning direction (exposure scanning direction of the first carriage 8) x 8 pixels in the main scanning direction (direction perpendicular to the exposure scanning direction: CCD electronic circuit scanning direction), a total of 6 pixels.
It has 4 pixels.

Also, when averaging 64 pieces of 6-bit data, if you add all the data and then reduce it to 1/64, a 12-bit adder is required as an adder, but in this example, processing is performed using an 8-bit adder. I have to.

First, to explain the addition of 8 pixels in the sub-scanning direction, the first data is latched in latch 1, added to the second data in adder 1, and the added value data is latched in latch 2. The third data is latched in latch 1, added to the fourth data by adder 1, and further added to the data in latch 2 by adder 2, resulting in 4 pixel data (gradation data).
The sum is output from adder 2. This data is latch 3
latched to.

Similarly, when the fifth to eighth data are added and output from the adder 2, they are added to the data in the latch 3 by the adder 3, and data for each eight-pixel system in the sub-scanning direction is output.

Note that the output of adder 1 becomes 7 by adding 6-bit data.
The output of adder 2.3 is the addition of 7-bit data, and the processing result of adder 2.3 is 8 bits, but the output takes the upper 7 bits and essentially converts the added data into 17 bits.
The value is set to 2.

Next, addition in the main scanning direction will be explained. The average value of the eight pixels output from the adder 3 is stored in the RAMI for one main scanning line. When the second line is output from the adder 3, the adder 4 adds it to the contents of the RAM1 and stores it in the RAM2. This adder converts the 1st+2nd line data into R
It is stored in AM2. Then, when the third line is output from the adder 3, the adder 4 adds it to the contents of the RAM 2 and stores it in the RAMI. Similarly, RAMI, 2 alternately outputs (reads) and stores added data, and when the 8th line is output from adder 3, it is added to the contents of RAM 1 by adder 4, and 8 lines of added data are output. be done. Here, like adder 2.3, adder 4 also averages (
1/2) data will be output. In this embodiment, two 4-bit binary full adders (74283) are used in parallel as adders.

In addition, recently 64 gradation output has been made from 8 x 8 matrix to 4
A submatrix method is used that cuts out a ×4 matrix. This circuit can be adapted to various matrix sizes by changing the number of latches and adders on the sub-scanning side.

Next, the masking processing circuit 106 and the UCR processing circuit 1
07 will be explained. The arithmetic expression for masking processing is generally expressed as follows.

YOall a12 a13 YiMO=
a21 a22 a23 MiCOa31 a3
2 a33 CiY 1. M 11 Ci
: Data before masking.

Yo2MO9Co: Data after masking.

The general formula for UCR processing is YO'all'a12'a13' YO
MO' = a21'a22'a23' M
OCO'a31'a32'a33' C
It can be expressed as 0Bk0'a41'a42'a43'. From the above two equations, YO'MO'= CO2 BkO'all'a12'a13' all a12
a13 Yia21'a22'a23' a
21 a22 a23 Mia31'a32'
a33' a31 a32 a33 C1a41'
a42'a43' a 11" a 12" a 13" Y i=
a21” a22” a23” Mia 31”
a 32” a 33” C1a41” a42
A new coefficient is determined as "a43". Coefficients of the above calculation formula (such as "all") that perform both masking processing and UCR processing at the same time
is calculated in advance and substituted into the above equation to obtain the scheduled input Yi of the masking processing circuit 106.

The calculated value (Y
o', etc.: outputs of the UCR processing circuit 107) are stored in the ROM in advance. Therefore, in this embodiment, the masking processing circuit 106 and the UCR processing circuit 10
7 consists of a set of ROMs, and data at addresses specified by inputs Y, M, and C to the masking processing circuit 106 is given to the buffer memory 108 and the gradation processing circuit 109 as the output of the UCR processing circuit 107. It will be done.

Generally speaking, the masking processing circuit 106 performs Y,
The UCR processing circuit 107 is for correcting the M and C signals, and the UCR processing circuit 107 is for correcting color balance in overlapping toners of each color.

Next, the buffer memory 108c + of the image processing unit
108 ml 108 y will be explained. These simply generate a time delay corresponding to the distance between the photoreceptor drums. The writing timing of each memory is simultaneous, but the reading timing is as shown in FIG. The memory 108c is operated in accordance with the modulation activation timing of the laser 43c, and is different from each other. The capacity of each memory is when A3 is the maximum size. Memory 108y is at least 24% of the maximum amount required for an A3 document, memory 108m is 48%, and memory 1
It should be about 72% for 08c. For example, the reading pixel density of COD is 400 dpi (dots/inch: 1
5.75 dots/mm), the memory 108y should have a capacity of about 87 bytes, the memory 108m should have a capacity of about 174 bytes, and the memory 108c should have a capacity of about 261 bytes. In this embodiment, since 64 gradations and 6-bit data are handled, the capacities of the memories 108y, 108m and 108c are 87, 1174 and 2, respectively.
I am 61 years old and have a part-time job. When calculating the memory address in units of 6 bits instead of units of bytes (8 bits), the memory address is 108y: 116KX6.
Memory 108m: 232K x 6 bits and Memory 108c: 348K x 6 bits.

FIG. 12 shows the configuration of the memory 108c, which has the largest capacity. Note that the other memories 108y and 108m have similar configurations. However, the memory capacity is small. The outline of the memory configuration will be explained with reference to FIG. 12. The input data memory has a 384K×6 bit configuration using 36 84K×1 bit memories as shown in DRAMI to 6.

The data that has undergone UCR processing is stored in FiF, which is a first-in/first-out (F i F o) memory.
Write to oRAM1,2. This is for correcting the difference between the output timing of the output data of the UCR process and the write timing of the memories DRAMs 1 to 6, and serves as a buffer for approximately one line. The data written to the FiFoRAMs 1 and 2 is written to the DRAMs 1 to 6 at addresses sequentially determined by the counter 1 starting from address O.

Next, the address of counter 1 is incremented by 1 and the next data is written. In this way, data is sequentially transferred to DRAM1.
~6 and is reset when it reaches 884K,
It is also written starting from address 0.

When counter 1 advances the address to 384 from the start of writing, data is transferred from DRAMs 1 to 6 to FiFoRAMl,
Writing (reading from DRAMs 1 to 6) is started at 2. At the start, the counter 2 is reset, and the data at address O is first written to the FiFoRAMs 1 and 2, and the counter 2 becomes address 1 and is sequentially read out in the same manner as writing.

When this counter 2 also reaches 384K, it is reset and written starting from address O. The data written to the FiFoRAMs 1 and 2 is sent to the gradation processing circuit 109 and then to the laser driver 1.
It is output based on the synchronization signal from 12c. Data selector 1 selects the address (count data) of counter 1 or counter 2, and when writing data to DRAM 1 to 6, the address data of counter 1 is used, and when reading data, the address data of counter 2 is used. is output. Data selector 2 is 64 x 1
Since the bit addresses of DRAMs 1 to 6 are determined by a multiplexer of upper 8 bits and lower 8 bits, this is used to select upper/lower bits of the 16-bit address. The decoder is an address decoder for selecting 6 blocks of DRAMs 1 to 6 every 64 for 384 addresses.

Next, the gradation processing circuit 109 of the image processing unit will be explained. This circuit 109 is a circuit that generates a pattern corresponding to the density from each of Y, M, and C gradation data, and is constituted by a ROM.

The 6-bit gradation data can represent density information of 64 gradations. Ideally, if the dot diameter of one dot could be varied in 64 steps, there would be no need to reduce the resolution, but in laser beam electrophotography, the dot diameter modulation is only stable at about 4 steps at most.
Generally, the concentration pattern method and the combination of the concentration pattern method and beam modulation are often used. Here, a processing method of expressing 64 gradations using an 8×8 matrix is used. circuit 109
has 64 types of 8×8 density patterns per group, and uses a method of outputting 8-bit data in the sub-scanning direction based on gradation data and main-scanning address.

Now, if we assume that the density pattern is 64 patterns (referred to as 1 group) created based on the binarized data in which the threshold levels are distributed in a spiral shape as shown in Fig. 13(a), this pattern is When the density is O, the number of toner dots to be applied in the 8 x 8 matrix is O, and the toner is applied to the number of dots represented by the density data.When the density is 32, the number of dots toner is applied is O, as shown in Fig. 13 (a) when the density is 32. Toner is applied to the shaded area. Therefore, a certain column of data is sequentially input to the processing circuit 109, 8-bit data is output in data order starting from main scanning address 1, and by parallel-to-serial conversion and output, data for one line in the sub-scanning direction can be obtained. It will be done. After outputting this data eight times in the main scanning direction (eight line processing), the next data string is input.

For example, the main scanning 3 data of data strings 20, 32, and 40 is as follows. Although 64 gradation expression using an 8×8 matrix is shown here, combinations with dot diameter modulation, submatrix methods, etc. have been proposed as methods for increasing resolution.

Similar gradation expression can also be achieved by changing the pattern or by outputting from the pattern. Regarding color processing, the Y, M, C, and Bk density patterns may not be the same pattern, but the pattern generation angle may be changed for each color in order to prevent moiré. That is, a plurality of pattern groups are created and patterns of different groups are assigned to each color.

The recording signals assigned to Bk include the dot pattern (binary code) from the black separation circuit 104 and the UCR processing circuit 10.
It is necessary to synthesize the density pattern (gradation pattern signal) generated from the Bk gradation information from 7. Simply put, for black in the text area, the resolution is higher when toner is applied based on the binary code from the black separation circuit 104 than when toner is applied based on density pattern information. However, in gradation image areas such as photographic areas, on the contrary, toner application based on density pattern information has higher image reproducibility.

The following method can be considered for synthesizing the dot pattern (binary code) from the black separation circuit 104 and the density pattern (gradation pattern signal) generated from the Bk gradation information from the UCR processing circuit 107. That is, (1) simply take the logical sum of both (if at least one is black, toner is applied: recorded). (n) In an 8×8 matrix division, when the black separation circuit 104 outputs black to be recorded within the matrix, the output of the black separation circuit 104 is assigned to that matrix, and when there is no output, density pattern data is assigned.

and (III) When the black separation circuit 104 outputs the black to be recorded in the 8×8 matrix division, the output of the black separation circuit 104 is assigned to that matrix, and the number of “black” output by the black separation circuit 104 is assigned. is compared with the "black" number of the density pattern to be assigned to the matrix, and the number in which the latter exceeds the former is randomly assigned to the white part of the matrix.

If black (diagonal lines) are distributed in the 8×8 matrix area as shown in FIG. 13(b), the output of the black separation circuit 104 will be distributed as shown in FIG. 13(c), and the UCR processing circuit When the density pattern specified based on the Bk output of 107 has the heat distribution shown in FIG. 13(d), according to the method (I) above, the record shown in FIG. 14(a) is obtained. According to the method (n) above, the recorded signal shown in FIG. 14(b) is obtained, and according to the method (III) above, the recorded signal shown in FIG. 14(C) is obtained. is obtained.

The above method (I) is simple in terms of hardware, but as shown in FIG. 14(a), recorded black often increases.
Further, although one of the purposes of this embodiment is to improve the resolution of black characters, the end portions of the black image become black and blurred, which is a relatively undesirable result.

In the above method (n), data processing is divided into 8×8 matrix sections, and it is determined whether or not there is an output "black" of the black separation circuit 104 in one section. This can be done by assigning output. In other words, it can be realized with relatively simple hardware and logic. Moreover, this method can achieve the purpose of increasing the resolution of characters. However, if the image is a half-tone image, the density of black will be 5 dots lower than when the density pattern is assigned.

The above method (III) solves the problems of (I) and (II). However, in reality, although the difference is easily determined, the hardware and logic for randomly assigning the difference to the white area become complicated.

As a result of the above considerations, this embodiment adopts the method (II) described above from the viewpoint of improving the resolution of black characters.

This method is performed by data selector 110 shown in FIG.

FIG. 15 shows the configuration of the data selector 110.

0 (L: white) for each pixel from the black separation circuit 104.

1 (H: black) data is output in parallel every 8 bits by a serial/parallel converter, and if the OR gate ORI has even one black (1) among the 8 bits, all ``1'' will be output (
0), outputs "0". This output is stored in RAMI for one line, and when the second line is input, it is stored in RAMI.
Take an OR with the first line data stored in I and store it in RAM.
Store in 2. In this way, the data for 8 lines are sequentially ORed.

During this time, the parallel-converted 0 (L: white) and 1 (H: black) data for each pixel from the black separation circuit 104 is written into a line buffer with a capacity for 8 lines. When this write is completed, the timing pulse becomes 1 and the AND gate A
NDI is opened, data is given to the data selector line by line from the line buffer, density pattern data is given to the data selector line by line from the gradation processing circuit 109, and data in RAM2 is repeatedly read out. and is applied to the control data input terminal of the data selector.

When there is output heat from the black separation circuit 104 in the 8×8 matrix section, the output of the RAM 2 is 1, so the data selector supplies the output of the line buffer to the laser driver. When no output from the separation circuit is black, density pattern data is given.

The peak detection circuit 115 of the image processing unit is meaningful in the monochromatic black copying mode, converts each of the R2O and B signals into analog signals, compares the three analog signals, and selects the highest value of the three signals. Binarization circuit 116
Output to.

The binarization circuit 116 converts the input signal into black (1: recording).

It is binarized into a signal indicating white (0: non-recording). The binarized signal is given to the data selector.

The synchronization control circuit 114 determines the activation timing of each of the above elements and matches the timing between each element.

A microprocessor system that controls the copying machine controls copying in various modes set on the console, and controls not only the image reading and recording system shown in Figure 2, but also the photoconductor power system, exposure system, and charger system. , developing system, fixing system, etc.

The copying machine of this embodiment is capable of not only full-color copying but also single-color copying, and is equipped with a switching instruction key switch on the console for switching settings between full-color mode and single-color black mode.

The mode setting according to the operation of this switch has already been explained. Here, the operation when the monochromatic black mode is set will be explained.

The image scanning unit including the first carriage operates in the monochromatic black mode in the same manner as in the full color mode, and color signals of R, G and 83 colors are outputted from the γ correction circuit 103. The peak detection circuit 115 and binarization circuit 116, which did not operate in the full color mode, operate, and the complementary color generation and black separation circuits 104 to gradation processing circuit 109, which operate in the color mode, as well as the laser driver. 112
and laser 43y+m,C does not operate in monochromatic black mode. The operation or non-operation of these circuits is determined by control operations of the synchronous control circuit 114 based on instructions from the processor system. As for the output of the γ correction circuit 103, a peak detection circuit 115 supplies the analog voltage of the highest level among the three voltages to the binarization circuit 116. Binarization circuit 1
16 has a threshold level set to a predetermined value, and the input is compared with this level, converted into a 1-bit digital signal, and provided to the data selector. This output is given to laser driver 112 through a data selector. Laser driver 112 energizes laser 43 based on the applied signal. That is, the laser is modulated and controlled based on the signal.

On the other hand, in the recording system, in monochrome black mode, charger 19,
The developing unit 20, the transfer charger 29, and the polygon mirror drive motor 41 stop operating, and the other operations operate in the same manner as in the full-color copy mode. These operations and non-operations are controlled by their drivers according to instructions from the processor system.

(Effects) In the device of the present invention, the rotation of the polygon motor is maintained at a high speed in accordance with the data processing speed. In other words, laser writing is Bk-+C+M-Y- line by line.
Bk... and so on. In this way, the A4 copy speed will increase to 174.
If the line speed is 25 nun/sec and the paper spacing is 40 mm, then (60X25) / (210+4
0) = 6 (copy/m1n) And for A3 size, it is approximately 3 (copy/m1n), which is twice the speed of the drum method. The advantages of being able to use thick paper and full-page images are still available, and the 25 mm
/see line speed has great advantages such as less noise and power consumption (and improved reliability such as toner scattering).

[Brief explanation of the drawing]

Fig. 1 is a block diagram of a color copying machine according to an embodiment of the present invention, Fig. 2 is a block diagram of the electrical equipment of the apparatus shown in Fig. 1, and Fig. 3 is a conventional one-drum color copying machine; The figure is a block diagram of the electrical component of the device shown in FIG. 3, FIG. 5 is a conventional four-drum color copying machine, FIG. 6 is a block diagram of the electrical component of the device shown in FIG. 5, and FIG. 7 is the invention of the present invention. 8 is a timing chart of the apparatus according to the embodiment of the present invention, FIG. 9 is a block diagram of the averaging data compression circuit, and FIG. 11 is a block diagram of the averaging data compression circuit. Figure 10 is a timing chart of the circuit, Figure 12 is a block diagram of the buffer memory section, Figure 13 is a timing chart of the circuit.
15 and 14 are explanatory diagrams of density patterns, FIG. 15 is a block diagram of the data selector section, and FIG. 16 is a block diagram of the interface between the microprocessor system and the driving section. DESCRIPTION OF SYMBOLS 1... Contact glass, 2... Original illumination lamp, 3... First mirror, 4... Second mirror, 5...
Third mirror, 6... Imaging lens, 7... CCD, 1
3...Rotating polygon mirror, 14...fθ lens, 15...
-Fourth mirror, 16...Fifth mirror, 17...Front tilt correction cylindrical lens, 18...Photosensitive drum, 19...Charger, 20...Developing unit, 2
DESCRIPTION OF SYMBOLS 1... Cleaner unit, 22... Transfer paper cassette, 24... Registration roller, 25... Transfer belt,
26...Recording paper, 27...Feeding roller, 29b
k, 29y129m, 29C...transfer charger,
36... Heat fixing unit, 41... Polygon mirror drive motor, 43+ 43y, 43m+43c, 43bk...
・Semiconductor laser, 44bk, 44y+ 44m+
44c... Photosensitive drum, 50... Filter, 5
DESCRIPTION OF SYMBOLS 1...Sensor, 101...Shading correction circuit, 102...Multiplexer 103...γ correction circuit, 104...Complementary color generation, black separation circuit, 104a...
Nant Gate, 104c, 104m, 104y...Digital comparator, 104sh...Threshold setting switch,
105... Averaging data compression circuit, 106... Masking processing circuit, 107... UCR processing circuit, 108
c, 108m, 108y...buffer memory, 109
... Gradation processing circuit, 110 ... Data selector, 1
12...Laser driver, 113...Semiconductor laser, 114...Synchronization control circuit, 115...Peak detection circuit, 116...Binarization circuit, 117...External interface

Claims (1)

[Scope of Claims] 1) An image processing apparatus having a plurality of image forming parts, in which a plurality of image data printed on the same transfer paper are processed line-sequentially by the same circuit. 2) The image processing apparatus according to claim 1, wherein the plurality of image data are obtained by color-separating the same color image. 3) The image processing apparatus according to claim 1, wherein the image processing apparatus performs high-speed recording using a single image forming portion and single image data by switching modes in the same apparatus.