JPH065893B2 - Synchronous controller for color digital copier - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a synchronous control device for a color digital copying machine which transfers a color digital signal read by a color image information reading means in synchronization with the color digital copying machine. Is.

[Conventional technology]

Conventionally, when obtaining a hard copy of a color image, for example, in a color printer such as a thermal transfer system or an electrophotographic system, usually Y (yellow), M (magenta), C (cyan), BK
A hard copy of a full-color (all colors) image is obtained by a so-called subtractive color mixing method in which (black) color developers are successively superposed. In this case, the Y image, the M image, and the C image must be accurately superimposed on the recording medium (recording paper). For example, the deviation width between the images is 0.1 m.
Even at about m, there was a problem that the color image was blurred and lacked in sharpness, and the color became turbid and the saturation decreased.

For this reason, conventionally, an image memory for at least one page is provided, image information is read from the image memory in synchronization with a reference signal at the leading edge of the image, and this is repeated in the order of Y, M, and C. The colors are matched by printing. Usually, such a color printer or the like is connected to a host computer that controls the whole, and the above-mentioned image memory is included in a large-capacity memory (for example, MT (magnetic tape) or magnetic disk) of the host computer. Therefore, it has a storage capacity of three color data of Y, M, and C.

On the other hand, in a digital color image copying system equipped with a digital image reading system, at least one image memory is provided for the above-mentioned synchronization, and the image information sequentially color-separated in the order of Y, M, C is read. Then, a method of storing the read information in the image memory, synchronizing with the reference synchronizing signal, and sequentially printing out the image information is also considered.

[Problems to be solved by the invention]

However, in a high pixel density digital color image copying system, for example, when reading image information at 16 pel / mm and storing in A4 size (297 x 210 mm),
The amount of image information is 16 megabits (Mbit) per sheet, and if this is held for three sheets of Y, M, and C, the role is 48 Mbits, which is an enormous storage capacity.

The high pixel density digital color copying system as described above is relatively high speed, and for example, the reading or writing speed of one pixel is several tens of nanoseconds (nsec).
Has become. For this reason, a high-speed semiconductor memory is required, and even if only one image memory is provided, for example, using the currently available 64-kilobit (Kbit) high-speed static RAM (random access memory), approximately 250 This is necessary, and in the case of three image memories, 750 high-speed static RAMs are required, and there is a problem that the scale manufacturing cost becomes enormous.

Further, in order to solve these problems, a plurality of line buffer memories are provided to perform accurate color image superposition, but the line buffer memory may not be used due to variations in the exposure scanning speed and rise time of the optical system. In some cases, the color misregistration of the device cannot be completely absorbed, which has a great influence on the output image, resulting in a problem that a clear color image cannot be obtained.

The present invention has been made to solve the above problems, and is a low-cost color digital copy capable of outputting a clear color image by transferring a color digital image signal from a color reader to a color printer without color deviation. The purpose is to obtain a machine synchronous control device.

[Means for solving problems]

A synchronous control device for a color digital copying machine according to the present invention is a dot data write signal sent from a color image information reading means to a line buffer and a read signal sent from a digital color printer to a line buffer memory. Further, there is provided a detecting means for detecting a deviation of the read timing of the dot data and an adjusting means for adjusting the sending of the write signal according to the deviation of the timing detected by the detecting means.

[Action]

In the present invention, the detection means reads the dot data from the write signal of the dot data sent from the color image information reading means to the line buffer and the read signal sent from the digital color printer to the line buffer memory. The timing deviation is detected, and the adjusting means adjusts the write signal transmission timing according to the deviation.

〔Example〕

FIG. 1 is a block diagram showing a configuration of an embodiment of the present invention. Reference numeral 1 is a digital reader, which is composed of an optical scanning system and color image information reading means, and the like, and stores the read dot data of each color component in a line buffer memory 2. Send to. A digital color printer 3 receives dot data for each color sent from the line buffer memory 2 and forms an image of Y, M, C, BK data on a recording medium. Reference numeral 4 denotes a detection means, which detects a shift in read timing by receiving a write signal sent from the digital reader 1 to the line buffer memory 2 and a read signal sent from the digital color printer 3 to the line buffer memory. To do. An adjusting means 5 receives the shift signal sent from the detecting means 4, judges whether or not the value exceeds a reference value preset according to the capacity of the line buffer memory 2, and sends the write signal. The adjustment signal for adjusting is sent to the digital reader 1. This adjustment signal becomes a drive signal for an optical scanning system (not shown) of the digital reader 1. Next, the operation will be described.

The dot data sent by the digital reader 1 is sequentially sent to the line buffer memory 2, and according to the read signal sent from the digital color printer 3,
Y, M, C, BK stored in the line buffer memory 2
Data (image data) is read for each color component, and a scanner (not shown) is controlled to form a latent image on the photosensitive drum. Thereafter, a color image is formed on the recording medium by a known electrophotographic method.

At this time, since the amount of data that can be written in the line buffer memory 2 is set in advance, the image shift may occur unless the image data is read in synchronization with the image forming operation on the printer side. The deviation between the write signal sent from the reader 1 and the read signal sent from the digital color printer 3 is detected by counting by a counting means such as a counter circuit, and the detected deviation signal is sent to the adjusting means 5. To do. The adjusting means 5 compares the value of the shift signal sent from the detecting means 4 with a reference value set in advance according to the capacity of the line buffer memory 2,
The adjusting means for adjusting the sending of the write signal is sent to the digital reader 1. As a result, the image data is written in the line buffer memory 2 in synchronization with the image forming operation of the digital color printer 3, and the image data stored in the line buffer memory 2 is sent to the digital color printer 3 in synchronization with the read signal. To be done.

FIG. 2 shows an example of a schematic internal configuration of a digital image processing system according to the present invention. As shown, this system has a digital color image reader (hereinafter,
It has a color reader 11) and a digital color image printing device (hereinafter referred to as a color printer) 12 below. The color reader 11 reads color image information of an original for each color by a color separation unit described later and a photoelectric conversion element such as a CCD and electrically converts the color image information into a digital image signal. The color printer 12 is an electrophotographic laser beam color printer that reproduces a color image for each color according to a digital image signal, and multiple-rotatably transfers and records in a digital dot form on a recording paper.

First, the outline of the color reader 11 will be described. Reference numeral 13 is a document, and 14 is a document scanning unit for scanning the document 13. The original scanning unit 14 includes a rod array lens 1
5, a multiplication type color separation line sensor (hereinafter referred to as a color image sensor) 16 and an exposure lamp 17 are incorporated. Reference numeral 18 is a wiring code of the original scanning unit 14, 1
Reference numeral 9 is a cooling fan, and 20 is an image processing unit connected to the document scanning unit 14 through the wiring cord 18.

When one scan is performed in the direction of arrow A in the figure to read the image of the document 13 on the document table of the document scanning unit 14, the exposure lamp 17 in the document scanning unit 14 is turned on at the same time, and the reflected light from the document 13 is rod arrayed. The light is guided by the lens 15 and focused on the color image sensor 16 which is a sensor for reading color information.

Further, 21 is an actuator provided below the document scanning unit 14, and 21a and 21b are actuators 21.
It is a position sensor that detects the scanning position of the document scanning unit 14 via the, and includes a micro switch or the like.

Next, the outline of the color printer 12 will be described.

Reference numeral 31 denotes a scanner, which is a laser output unit for converting the image signal from the color reader 11 into an optical signal (see FIG. 6) 31.
a, Polyhedral mirror 31 of polyhedron (for example, dodecahedron)
b, a motor (not shown) for rotating the polygon mirror 31b, and an f / θ lens (imaging lens) 31c <reflection mirror 31d, beam detector 31e, and the like. Reference numeral 32 is a reflecting mirror that changes the optical path of the laser light, and 33 is a photosensitive drum. The laser light emitted from the laser output unit is reflected by the polygon mirror 31b, passes through the f / θ lens 31c and the reflection mirror 31d, and scans the surface of the photosensitive drum 33 in a plane to form a latent image corresponding to the original image. .

Further, 34 is a primary charger, 35 is a full-face exposure lamp, 36
Is a cleaner unit that collects residual toner that has not been transferred. 37 is a pre-transfer charger, and these members are arranged around the photosensitive drum 33. Reference numeral 38 denotes a developing device unit for developing the electrostatic latent image formed on the surface of the photosensitive drum 33 by laser exposure, and 39y, 39m, 39
Reference characters c and 39bk are toner hoppers for holding the preliminary toner. Reference numerals 40y, 40m, 40c and 40bk denote developing sleeves, which are in contact with the photosensitive drum 33 to directly perform development. Reference numeral 41 is a screw for performing the phase of the developer, and these toner hoppers 39y to 39bk and the developing sleeves 40y to 40y.
The bk and the screw 41 constitute a developing device unit 38, and these members are arranged around the rotation axis P of the developing device unit 38. For example, when a yellow toner image is formed, yellow toner development is performed at the position shown in this figure, and when a magenta toner image is formed, the developing unit 38 is rotated about the axis P in the figure to expose the toner image. The developing sleeve 4 in the magenta developing device is located at a position in contact with the drum 33.
Place 0m. Cyan and black development work similarly.

A transfer drum 42 transfers the toner image formed on the photosensitive drum 33 onto a sheet. An actuator plate 43 detects the moving position of the transfer drum 42. A position sensor 44 detects whether or not the transfer drum 42 has moved to the home position by coming into contact with the actuator plate 43. A transfer drum cleaner 45 removes toner remaining on the transfer drum 42. Reference numeral 46 denotes a paper pressing roller that brings the fed paper into close contact with the transfer drum 42. 47 is a static eliminator, which neutralizes the transfer drum 42. Four
A transfer charger 8 transfers the visualized toner image on the transfer drum 42 onto a sheet. In addition, the above 43, 44, 4
5, 46 and 48 are arranged around the transfer drum 42.

On the other hand, 49a and 49b are sheet feeding cassettes for storing sheets,
50a and 50b are these paper feed cassettes 49a and 49b
Paper feed rollers for feeding paper from the paper, and timing rollers 50a to 50c for timing the paper feed and the paper feed.
1, the leading end is carried on the transfer drum 42 while being supported by the gripper described later, and the process proceeds to the image forming process.

52 is a peeling claw that peels the sheet from the transfer drum 42 after the image forming process is completed. Reference numeral 53 is a conveyor belt for conveying the peeled paper, and 54 is an image fixing unit for fixing the paper conveyed by the conveyor belt 53. The image fixing section 54 has a pair of thermal pressure rollers 54a and 54b.

Next, the embodiment shown in FIG. 2 will be described in more detail with reference to the drawings starting from FIG.

In the color image sensor 16 described above, for example, as shown in FIG. 3 (a), a chip having 1024 pixels is formed in a zigzag pattern with one pixel having an area of 62.5 μm (1/16 mm) square.
5 chips 6-1 to 16-5 are arranged, and each pixel is divided into three parts of a size of 20.8 μm × 62.5 μm as shown in FIG. Color separation filters of B (blue), G (green), and R (red) are attached to each, and the original is scanned in the direction of the arrow in FIG. read.

FIG. 4 (a) shows the color separation image data read by the above-mentioned five-chip color image sensors 16-1 to 16-5 arranged in a staggered pattern, quantized into 8-bit digital data, and the color to be described later. An example of a color image reading circuit until input to a correction circuit and an image data processing circuit is shown.

First, the analog pixel signals color-separated into the R, G, and B color components of the original 13 by the above-described color image sensors 16-1 to 16-5 are amplified by the amplifiers 61a to 65a in the first stage, and the logarithmic conversion circuit 61b. Is converted into the density value of the pixel by the process of .about.65b. At this time, each image signal is output from the serial color image sensors 16-1 to 16-5 in the order of R1 → G1 → B1 in synchronization with the clock CLK shown in the timing chart of FIG. 4 (b).

Then, by the sample hold circuits 61c to 65c,
Sample-and-hold of the input image data is used at a timing synchronized with the clock CLK shown in FIG. 4 (b), and thereafter analog-digital (A / D) converters 61d to 65d are used.
A / D conversion is performed by and is quantized into 8-bit 256-gradation image data.

In the color-separated and quantized image data, the color-separated data DATA for the same pixel is serially transferred in a time division manner as shown in FIG.
In order to perform color correction processing on this color separation data DATA by a color correction circuit described later, each data DR ₁ , DG ₁ , D
B ₁ (where R, G and B are red, green,
Corresponds to blue. The same shall apply hereinafter) in advance in the same phase.

Therefore, a latch pulse LP having a phase difference in time is provided.
The data DR ₁ , DG ₁ , DB ₁ of the color separation data DATA is sequentially latched by the R ₁ , LPG ₁ , LPB ₁ latch circuit 61e.
To 65e, and latch these latch circuits 61e to 65e.
e latch output of _{LP R, LP G,} the latch pulse LCH the LP _B are latched in the latter stage of the latch circuit 66.
As a result, the color separation data of the same pixel is finally latched in the latch circuit 66 in the same phase.

Further, since the color image sensors 16-1 to 16-5 are arranged in a staggered manner as shown in FIG. 3 (a), the buffer memory 67 _R is used to connect the sensor output to one output line. , 67 _G , 67 _B are buffered with data for a plurality of lines and are output to the subsequent stage as color-separated image data DR, DG, DB for one line continuous for each color of R, G, B.

8-bit color-separated image data DR, DG, DB having the same phase for the same pixel obtained as described above.
Is subjected to predetermined processing by the circuit shown in FIG. That is, the color correction circuit 71 in this figure performs the processing disclosed in the following section, which is usually called masking, and the black plate generation and undercolor removal circuit 72 performs the processing disclosed in the following section.

Masking process: The color correction circuit 71 performs a matrix operation represented by the following equation (1) on the input color separated image data DR, DG, DB to absorb the unnecessary color component of the print toner.

Here, the coefficients a _i , b _i , and c _i (i = 1 to 3) are masking coefficients that should be set to appropriate values. Further, Y, M, and C are output signals corresponding to the colors of yellow, magenta, and cyan.

In the black plate generation and undercolor removal circuit 72, when the above-mentioned minimum value MIN (Y, M, C) of the output signals Y, M, C = k (constant), Y ′ = Y−αk, M ′ = M-βk,
Toner amount Y ′ to be printed by the calculation of C ′ = C−γk,
M ′ and C ′ are obtained, and the BK signal of BK (black) = δk is used as a black plate for black printing. Where the coefficient α,
β, γ, and δ are set to appropriate values in advance.

Next, the respective image data Y ', M', C'obtained by the above-mentioned black plate generation and undercolor removal circuit 72 become the basic data of the toner image finally printed by the color printer 12. However, as will be described later, the color printer 12 in this system uses a Y (yellow) toner image,
The toner image of M (magenta), the toner image of C (cyan) and the toner image of BK (black) cannot be printed out on the transfer paper at the same time. Since it is a printing system in which a color print image is finally obtained by sequentially superposing it, the above-mentioned black plate generation and undercolor removal circuit 7
The toner amount Y ′, M ′, C ′, BK of each color obtained in 2 is set by the selector 73 corresponding to the operation of the color printer 12.
Select two images. Therefore, in this system, one color image original is read and printed out.
Four document exposure operations and four toner image forming processes are required.

Now, the color separation image 73a selected by the selector 73 corresponding to the operation of the color printer 12 is separated into the character area 74b and the halftone image area 74a by the image area separation circuit 74, and the halftone image The image area 74a is subjected to multi-valued processing (normally called dither processing) by the multi-valued processing circuit 75, and the character area 74b is
The binarization processing circuit 76 performs binarization processing with a single threshold value, whereby the image data transferred in the above-mentioned 8-bit 256 gradations is image dot data 75a, 75b of "1" and "0". Convert to. The image dot data 75a and 75b pass through the OR gate 77 and the synchronous memory 7
Enter in 8. The synchronous memory 78 is a buffer memory necessary for printing out the color separation images read simultaneously with the original exposure scanning according to the present invention successively without causing color misregistration, and 79 controls the synchronous memory 78. The synchronous memory controller for transmitting the image dot data 75a and 75b to the color printer 12 via the interface 80.

Next, the image forming process of the color printer 12 shown in FIG. 2 will be described with reference to FIG.

The color-separated image signal read by the color reader 11 is expanded into dot image data (dot data) through the circuits shown in FIG. 5, and the dot data corresponding to this color image is finally converted into the sixth data. Laser output unit 3 shown in the figure
The laser light LB is modulated by 1a. The laser beam LB modulated corresponding to the image data is horizontally scanned at a high speed by the polygon mirror 31b rotating at a high speed within the width of the arrow AB in FIG. 6, and the f / θ lens 31c and the polygon mirror 31 are scanned.
An image is formed on the surface of the photosensitive drum 33 through b, and dot exposure corresponding to the image data is performed. One horizontal scanning of the laser beam corresponds to one horizontal scanning of the original image, and in this embodiment, 1 /
The width is 16 mm.

On the other hand, since the photosensitive drum 33 is rotating at a constant speed in the direction of the arrow L in the figure, the above-mentioned laser beam is scanned in the main scanning direction of the drum, and the photosensitive drum 33 is scanned in the sub scanning direction of the drum. Since the rotation is performed at a constant speed, the two-dimensional images are successively exposed to form latent images. A toner image is formed from the uniform charging by the primary charger 34 prior to this exposure → the above-mentioned exposure → and the toner development by the developing sleeves 40y, 40m, 40c and 40bk. For example,
By developing with the yellow toner of the developing sleeve 40y corresponding to the first original exposure scanning in the color reader 11, a toner image corresponding to the yellow component of the original 13 is formed on the photosensitive drum 33.

Then, the tip of the transfer drum 4 is supported by the gripper GP.
A yellow toner image is transferred and formed on the paper sheet PA wound around 2 by a transfer charger 48 provided at a contact point between the photosensitive drum 33 and the transfer drum 42. The same processing steps are performed for M (magenta), C (cyan), and BK.
By repeating each toner image on the paper sheet PA repeatedly for the (black) image, a full-color image with four-color toner is formed. Thereafter, the paper sheet PA is separated from the transfer drum 42 by the movable separation claw 52 shown in FIG. 2, guided to the image fixing section 54 by the conveyor belt 53, and heated by the heat pressure rollers 54 a and 54 b of the image fixing section 54. The toner image on the paper sheet PA is fused and fixed.

Next, Y, M, C, BK by the above-mentioned color reader 11
The color separation image corresponding to the toner image is repeatedly read, and the toner images of Y, M, C, and BK described above are sequentially superimposed on the paper sheet PA carried on the transfer drum 42 in the color printer 12 with high accuracy and without color shift. Control of image reading and image printing timing for simultaneous transfer
Description will be given with reference to the drawings.

In FIGS. 7A and 7B, T is an exposure start reference point. Reflected light from the document surface of the document 13 is guided by the rod array lens 15 of the document scanning unit 14 to form an image on the color image sensor 16, and the color image sensor 16 moves as the document scanning unit 14 moves in the direction of the arrow in the figure.
Thus, image reading is sequentially performed.

On the other hand, an actuator 21 is attached to the lower portion of the document scanning unit 14, and position signals are obtained at the positions of a home position sensor (ITOP sensor) 21a and a home position sensor (DTOP sensor) 21b fixedly installed on the main body. To be Normally, the stop is performed based on the output signal of the home position sensor 21a, and the reading of the document is performed based on the signal of the DTOP sensor 21b.

In the color printer 12, an image is written at the laser exposure position PH on the photosensitive drum 33. Further, a position sensor 44 fixedly installed on the main body and an actuator plate 43 attached to the transfer drum 42 are arranged on the circumference of the transfer drum 42 as shown in FIG. 6, and the toner image is transferred. The front end of the paper sheet PA is the actuator plate 4
The length on the circumference of 3 is a fixed l + Δl, and the home position sensor 21a and the DTOP in the color reader 11 are
It is slightly longer than the distance 1 between the sensors 21b.

First, when the position sensor 44 detects the leading edge a of the actuator plate 43 on the transfer drum 42 rotating in the direction of the arrow (clockwise direction) in the figure at a constant speed, the scanning movement of the document scanning unit 14 is started. (Fig. 7 (a)
Shown in FIG. 2), the document scanning unit 14 is connected to the DTOP sensor 21.
When it reaches b, the original is read, and accordingly the synchronous memory 7
Writing to 8 (shown in FIG. 5) is started. That is,
In the synchronous memory 78, the color separated image read from the leading edge T of the document is stored line by line.

On the other hand, on the color printer 12 side, when the trailing edge b of the actuator plate 43 on the circumference of the transfer drum 42 is detected, the above-mentioned synchronous memory 7 is detected from when the trailing edge b is detected.
8 is read from the beginning, and image writing to the photosensitive drum 33 by laser light modulation is started (shown in FIG. 7B). In FIGS. 7 (a) and 7 (b), a indicates the leading edge and the leading edge of the paper described later.

Since the distance from the laser exposure position PH on the photosensitive drum 33 to the transfer position Tr is equal to the distance from the position of the paper leading edge a to Tr in advance, the leading edge T of the document 13 is set.
From the leading edge T of the document, an image is formed line by line from the leading edge a of the paper. The synchronous memory 78 in the system of the present embodiment is 48 lines (line), that is, 16 pel / m 2.
When an image is read with a scanning density of m, it has a storage capacity of 3 mm width. The role of the synchronous memory 78 and the reason for the storage capacity of 48 lines will be described below.

In order to obtain a color image without color misregistration, as described in detail above, the first time the image reading of the yellow component and the formation of the yellow toner image of the original 13 are performed, and then the image reading of the magenta component is performed. Since the magenta toner image is formed, then the cyan component image is read, the cyan image is formed, and finally the black component image is read and the black toner image is formed, the beginnings of the images must always overlap accurately. Is mandatory.

Therefore, as described above, when the position sensor 44 detects the leading edge a of the actuator plate 43 of the transfer drum 42, the exposure scanning of the document scanning unit 14 is started, and the DTOP sensor 21b detects the leading end T of the document 13. At this point, the reading of the original image and the writing to the synchronous memory 78 are started, while the rear edge b of the actuator plate 43 is detected by the position sensor 44 and at the same time the image data is read from the synchronous memory 78 and the photosensitive drum is read. The image is written to 33.

However, since the transfer drum 42 is rotating at a constant speed, the position sensor 44 detects a leading edge a of the actuator plate 43 until a trailing edge b thereof is detected, that is, the document scanning unit. As shown in FIG. 8, the time t from when 14 starts at the stop position SR ₁ (at the point where the home position sensor 21a is arranged) to when it reaches the position SR ₂ (at the point where the DTOP sensor 21b is arranged) is shown in FIG. As described above, a variation that cannot be ignored occurs (fluctuation). The vertical axis of FIG. 8 represents time, and the horizontal axis represents moving distance.

This variation largely depends on conditions peculiar to the apparatus, such as friction with the main body due to the weight of the original scanning unit 14 with respect to the main body, tension of the drive wire (not shown), fluctuations in the rising characteristics of the drive motor, and the like.

Therefore, the maximum value Δtmax of the variation in FIG. 8 must be controlled so that the scanning distance does not exceed the capacity of the synchronous memory 78. That is, it is necessary to select the capacity of the synchronous memory 78 so that the image data corresponding to the maximum value of the variation amount fits in the synchronous memory 78. In the case of the present apparatus, the capacity calculated from this Δtmax is the data capacity of 48 lines.

FIG. 9 shows an example of the structure of the synchronous memory 78 described above.

As described above, when the document scanning unit 14 reaches the position of the DTOP sensor 21b, the document reading is started, and the first line of the document is written in the synchronous memory 78.
Rear edge b of the actuator plate 43 of the transfer drum 42
Is detected, the image data is read from the synchronous memory 78 and the image is written to the photosensitive drum 33 from the same first line. Therefore, the above-mentioned variation Δtmax is due to the synchronous memory 78.
Absorbed by.

Further, after the leading edge a of the actuator plate 43 of the transfer drum 42 is detected and then the document scanning unit 14 of the color reader 11 is started, the trailing edge b of the actuator plate 43 is detected rather than the original scanning. The unit 14 starts reading the leading edge T of the document, that is, DTOP
If the detection of the sensor 21b is not preceded by at least two lines, the read / write sequence in the synchronous memory 78 is reversed, and proper synchronous control is not performed.

Therefore, in the present system, as described above, the actuator plate 43 of the transfer drum 42 of the color printer 12 is used.
Between the detection of the leading edge a of the sheet and the start of the document scanning unit 14 of the color reader 11 and the delay means for providing a delay time and the trailing edge b of the actuator plate 43 and the synchronization. A delay unit for providing a delay time before starting the reading of the image data from the memory 78 is provided so as to perform an appropriate synchronization process.

FIG. 10A shows an example of the start delay circuit of the document scanning unit 14, and FIG. 10B shows a timing chart of the delay circuit.

As shown in FIG. 10A, after the scan motor ON signal SCAN for activating the scan motor for activating the scan motor of the document scanning unit 14 is input to the flip-flop 82a, the leading edge a of the actuator plate 43 is detected. The signal ITOP and the horizontal synchronization signal HSYNC (= beam detection signal sent by the beam detector 31e) are the AND circuit AN.
When the counter 81 counts the horizontal synchronization signal HSYNC by a predetermined number by inputting it to D, the counter 81
The flip-flops 82a and 82b are set by the count-up signal C / UP, and the drive signal M / ON of the scanning motor is output, whereby the document scanning unit 14 is started (see FIG. 10 (b)). The count value of the counter 81 that determines the delay amount is set by the preset switch 83. Further, the horizontal synchronizing signal HSYNC described above receives the laser beam LB scanned through the reflecting mirror 32 shown in FIG.
It is a synchronization signal output from e once for each horizontal scanning line, and is always sent from the color printer 12 to the color reader 11.

FIG. 11 shows a configuration example of an image reading delay circuit from the synchronous memory 78. When the rear edge b of the actuator plate 43 of the color printer 12 is detected, the detection signal ITO
The flip-flop (FF) 85 is set by P, and the counting operation of the counter 86 is started. Counter 8
6 is a horizontal synchronizing signal H sent from the beam detector 31e
SYNC is counted, the first stage FF 85 is reset by the count-up signal C / UP of the counter 86, the second stage FF 87 is set, and the read operation start signal R / ST of the synchronous memory 78 is output from the second stage FF 87. The preset value of the counter 86 is set to an appropriate value by the preset switch 88.

Depending on the set values of the delay counter 81 and the counter 86 described above, there is a variation in the time from the start of image data writing to the synchronous memory 78 to the start of image data reading, that is, the document scanning unit 14 starts from the position where the home position sensor 21a is arranged. Of the synchronous memory 78 so that the variation Δtmax in the time required to reach the position of the DTOP sensor 21b falls within 48 lines when converted into memory lines so that there is a difference of 24 lines before and after the standard position. It is set in advance. Therefore, the variation Δtmax can be absorbed up to a maximum of 47 lines of +24 lines and −23 lines, so that proper memory synchronization control is always performed.

As described above, it is possible to absorb the variation in the movement rising at the start of scanning of the document scanning unit 14 in the synchronous memory 78 and perform the color matching with high accuracy, but there is an abnormality in the drive motor of the document scanning unit 14 or the transfer mechanism. If it happens,
The variation may exceed the capacity of the synchronous memory 78. When such a situation occurs, a color shift corresponding to the variation appears in the image, and a proper copy image cannot be found.

Next, the detecting means of the present invention will be described with reference to FIGS.

FIG. 12 is a circuit diagram which constitutes the detecting means of the present invention.
00 is a counter, and the count value is set via the bus 102 by a command from the CPU 101. Reference numeral 103 denotes an I / O port to which error signals ERROR1 and ERROR2, which will be described later, are input. F1 to F5 are flip-flops, the flip-flop F1 is enabled by receiving the detection signal ITOP, and the output of this flip-flop F1 enables the subsequent flip-flop F3 to enable the error signal ER.
The ROR1 is output to the I / O input port 103. The flip-flop F2 is enabled in response to the detection signal DTOP, the output of the flip-flop F2 enables the subsequent flip-flop F4, and the AND circuit AND is established by the output of the flip-flop F4, and the horizontal synchronization signal HSYNC. Is input to the counter 100.

FIG. 13 is a timing chart for explaining the operation of FIG. 12, (a) shows the relationship between the detection signals DTOP and ITOP when Δtmax is within the capacity of the synchronous memory 78,
(B) shows detection signals DTOP, ITOP and error signal ER when Δtmax exceeds the capacity of the synchronous memory 78.
The relationship with ROR2 is shown, and (c) shows the relationship with the error signal ERROR1 when the detection signal ITOP is sent before the detection signal DTOP. Hereinafter, the case (a) will be described in order.

As shown in FIG. 7A, when the transfer drum 42 rotates after the copy sequence starts and the home position sensor 44 detects the actuator plate 43, the document scanning unit 14 starts and the document scanning unit 14 starts. 14 is a DTOP sensor 2 placed at the leading edge T of the document.
When 1b arrives, the detection signal DT is sent to the circuit shown in FIG.
OP is sent, and the detection signal DTOP causes the outputs of the flip-flops F2 and F4 to be "H", that is,
The chip is enabled, and the horizontal synchronizing signal HSYNC is input to the clock terminal CLK of the counter 100. Then, when the position sensor 44 detects the rear edge b of the actuator plate 43, the detection signal ITOP clears the flip-flop F4 and prohibits the input of the horizontal synchronizing signal HSYNC to the counter 100. The content of the counter 100 at this time point is the deviation amount, and when the deviation amount, that is, the count number falls within the count value instructed by the CPU 101, that is, in the case shown in FIG. The ERRORs 1 and 2 are not sent out, the normal sequence operation is continued, the motor ON signal M / ON for driving the document scanning unit 14 is sent out, and the document exposure is started.

Further, when the amount of deviation exceeds the capacity of the synchronous memory 78, that is, after the detection signal DTOP is transmitted as shown in FIG.
When 0 starts counting and the count value instructed by the CPU 101 is exceeded before the detection signal ITOP is detected, the ripple carry RC indicating the end of counting is output from the counter 100 by the output of the flip-flop F5 to “H”. , ”And the error signal ERROR2 is input to the I / O port 103. The CPU 101 reads the data input to the I / O port 103 via the bus 102, in this case, the error signal ERROR2, and detects the occurrence of an error.

Further, as shown in FIG. 13 (c), when reading is started before writing the image data in the synchronous memory 78 (shown in FIG. 5), that is, before the detection signal DTOP is transmitted, When the detection signal ITOP is detected,
The detection signal ITOP causes the outputs of the flip-flops F1 and F3 to be "H", and the error signal ERROR1 becomes the detection signal I.
It is sent to the I / O port 103 in synchronization with the fall of TOP. The CPU 101 reads the data input to the I / O port 103 via the bus 102, in this case, the error signal ERROR1 and detects the occurrence of an error.

Next, the adjusting means of the present invention will be described with reference to FIGS. 14 and 15.

FIG. 14 is a circuit diagram for explaining the adjusting means showing an embodiment of the present invention. Reference numeral 111 is a counter, which responds to the count value instructed by the CPU 101, and outputs a horizontal synchronizing signal HSYNC.
To count. An I / O port 112 outputs a motor drive signal SCAN for activating the document scanning unit 14 and a select signal BK / FW for instructing the document scanning unit 14 to move forward and backward. Reference numeral 113 is a flip-flop, which is enabled by the detection signal ITOP, and the counter 1
The load signal is output to 11. Reference numeral 114 denotes a flip-flop, which is enabled by a ripple carry RC output after the counter 111 has finished counting, and is a motor ON signal M / O for turning on the drive motor of the document scanning unit 14.
Output N.

FIG. 15 is a timing chart explaining the operation of the circuit shown in FIG.

Next, the operation will be described.

When the copy sequence is started, the CPU 101 causes the I
The motor drive signal SCAN and the forward / backward select signal BK / FW are set to "H" at the / O port 112. Here, when the detection signal ITOP is generated, the output of the flip-flop 113 becomes “H” in synchronization with its rising,
The counter 111 starts counting down. As described above, the clock terminal CLK of the counter 111 has CP
A value corresponding to the amount of deviation is set by U101.
When the counting operation of the counter 111 is completed, a ripple carry RC occurs, the output of the flip-flop 114, that is, the motor ON signal M / ON becomes “H”, and at this time, the document scanning unit 14 advances. C
When the PU 101 detects that a certain time (set by the document size) has passed by a timer (not shown),
The motor drive signal SCAN is set to "L" to stop the document scanning unit 14. Then, select signal BK / FW
Is set to "L" (reverse), the motor drive signal SCAN is set to "H" again, and the document scanning unit 14 is retracted to return to the home position SR ₁ .

Next, the control operation of the digital image processing system shown in FIG. 2 will be described with reference to FIGS. 16 to 19.

FIG. 16 is a flow chart for explaining the control operation of the digital image processing system shown in FIG. In addition, (1) ~
(9) shows each step.

When the copy sequence (Y; yellow) starts
(1), the transfer drum 42 rotates, and the actuator plate 43
When the position sensor 44 detects the position sensor 44, the document scanning unit 14 starts, the document scanning unit 14 reaches the DTOP sensor 21b arranged at the leading edge T of the document, the detection signal DTOP is sent, and the horizontal synchronizing signal HSYNC is input. To be done. This horizontal synchronization signal HSYNC is sent to the CPU 10
It is determined by 1 whether the count value set in the counter 100 has been exceeded, that is, whether a synchronization error has occurred (2). If NO, the counter 100 is cleared (3).
Next, the reading of the yellow image is started (4), and when the formation of the yellow image is completed, the counter 111 is set (described later) (5), and the magenta, cyan, and black image formation steps (1) to (). Do the same as 5), (6), (7), (8),
Control ends.

On the other hand, if the judgment in step (2) is YES, the error flow shown in FIG. 17 starts (9).

FIG. 17 is a flow chart for processing the synchronization deviation error in the flow of FIG. Note that (11) to (21) indicate each step.

When the step (2) of the flow of FIG. 16 is YES and the error signal ERROR2 is input to the I / O port 103, the color printer 2 is notified of the error occurrence (11) and the exposure lamp 17 is turned off ( 12), while sending a stop signal to the drive motor that drives the document scanning unit 14,
Reverse the drive motor (13), (14) to scan the original scanning unit 1
Wait for 4 to return to the home position (15), and when reaching the home position, increment the number of the error counter (not shown) that counts the number of errors by "1" (16), and then count the error counter. It is judged whether the value has exceeded the preset count value T (set arbitrarily) (17), and if YES, it is considered that self-recovery is not possible, and this color system stops (18) and waits for restoration. . On the other hand, if the judgment in step (17) is NO, that is, if the number of errors is less than T, either of the error signals ERROR1 and 2 is waited (19), and the error signal ERROR1 is detected. If so, the timing of writing the image data in the synchronous memory 78 is late, so the setting value of the counter 111 is decreased by k (arbitrarily set) and the process returns to step (1) (20). On the other hand, when the error signal ERROR2 is detected in step (9), the timing of writing the image in the synchronous memory 78 is early, so the set value of the counter 111 is increased by k and the process returns to step (1) (21).

FIG. 18 shows a color printer 1 when a synchronization error is detected.
It is a flow chart explaining operation of No. 2. Note that (31)
~ (35) indicate each step.

The color printer 12, which has received the synchronization error, immediately feeds the transfer paper 92 to the transfer drum 42 at this point, but immediately before the start of exposure of the photosensitive drum 33, the laser exposure is immediately stopped (31 ), The subsequent yellow development is not executed (32), and one color rotation is inserted (33). Then
It is judged whether or not the value of the error counter reaches the set value T (34), and if YES, the color printer 12 is stopped (3
5) If NO, return to step (1) to retry the latent image formation, development and transfer of the yellow image.

FIG. 19 is a flow chart for explaining the counter setting operation in the flow chart of FIG. Note that (41)
~ (44) indicate each step.

When the document scanning unit 14 returns to the home position, the CPU 101 reads the count amount (synchronous deviation amount) M of the horizontal synchronizing signal HSYNC from the counter 100 (41), and the read synchronous deviation amount M is the capacity N (48) of the synchronous memory 78. It is judged whether it is less than 1/2 of (line) (42), YE
If S, subtract the set value of the counter 111 by a predetermined amount ((N / 2) -M) and proceed to step (6) (43). If NO, set the set value of the counter 111 by a predetermined amount ((N / 2 ) -M) is added and the process proceeds to step (6) (44).

〔The invention's effect〕

As described above, the present invention reads dot data from the dot data write signal sent from the color image information reading means to the line buffer and the read signal sent from the digital color printer to the line buffer memory. Since the detecting means for detecting the timing deviation and the adjusting means for adjusting the sending of the write signal according to the timing deviation detected by the detecting means are provided,
The adjusting means can control the data writing timing to the synchronous memory so as to be within the capacity of the synchronous memory according to the amount of synchronous deviation detected by the detecting means, and a clear multi-color image with no color deviation can always be obtained. Further, when the amount of synchronization deviation is within the capacity of the synchronization memory, the writing of each color data into the synchronization memory is optimized, and there is an excellent effect that a clearer multicolor image is obtained.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a configuration block diagram showing an embodiment of the present invention, FIG. 2 is a schematic configuration diagram of a digital image processing system according to the present invention, and FIG. An arrangement configuration diagram showing an example of a unity-size color separation line sensor in the original scanning unit of FIG.
FIG. 3 (b) is an explanatory view showing an enlarged main part thereof, and FIG.
FIG. 4A is a block diagram showing the configuration of a color image reading circuit, FIG. 4B is a timing chart showing the signal waveforms of the circuit, and FIG. 5 is a configuration example of a circuit for correcting and synchronizing a color image signal FIG. 6 is a perspective view showing in detail the main part of the printer portion of FIG. 1, FIGS. 7 (a) and 7 (b) are operation mode diagrams of the system of FIG. 1, and FIG.
The figure is a characteristic diagram showing the time variation of the output of the sensor,
9 is a layout diagram showing a configuration example of the synchronous memory of FIG. 5, FIG. 10 (a) is a circuit diagram showing a configuration example of a start delay circuit of the document scanning unit of FIG. 1, and FIG. 10 (b). Is the tenth
11A is a timing chart showing the signal waveform of FIG.
5 is a circuit diagram showing a configuration example of a delay circuit for delaying image reading from the synchronous memory shown in FIG. 5, FIG. 12 is a circuit diagram which constitutes the detecting means of the present invention, and FIG. 13 is a diagram showing the operation of FIG. FIG. 14 is a timing chart for explaining the adjusting means showing an embodiment of the present invention, FIG. 15 is a timing chart for explaining the operation of the circuit shown in FIG. 14, and FIGS. 6 is a flowchart illustrating a control operation of the digital image processing system shown in FIG. In the figure, 1 is a digital reader, 2 is a line buffer memory, 4 is a digital color printer, 4 is detection means, and 5
Is adjustment means, is dot data, is Y, M, C, BK
Data is a write signal, is a read signal, is a shift signal, and is an adjustment signal.

Claims (1)

[Claims] 1. A color image information reading means for reading an original as dot data for each color component, and a plurality of line buffers for storing dot data for superimposing color images read by the color image information reading means without color deviation. In the color image copying system, a digital reader having a memory and a digital color printer for reading the dot data stored in each line buffer memory for each color component to form a full color image are connected. Deviation of the read timing of the dot data is detected from a write signal of the dot data sent from the information reading means to the line buffer and a read signal sent from the digital color printer to the line buffer memory. The detection means and this It means a color digital copying machine synchronous control apparatus being characterized in that comprising an adjustment means for adjusting the delivery of the write signal in response to the deviation of the timing detected.