JPH07303189A - Digital copying device - Google Patents

Abstract

PURPOSE:To detect a color normally without increasing the number of components and not incurring cost increase by providing a control means inhibiting the operation of a background elimination means when a multi-color copy is designated. CONSTITUTION:When a single color copying is designated by an operation panel 201, a CPU 146 of an image processing section 200 activates a video processing circuit 141 to execute elimination of background. On the other hand, when multi-color copy is designated, the operation of the circuit 141 is inhibited so as not to implement background elimination. Thus, since the operation panel 201 is used to select the multi-color copy mode and the circuit 151 is automatically inactive, defective color separation due to dispersion in the RGB background elimination circuit is avoided and a color is normally detected without provision of a special device.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital copying machine capable of outputting read image data in black and a color other than black.

[0002]

2. Description of the Related Art As one of conventional digital copying machines,
There is provided a digital copying apparatus having a two-color copy mode capable of outputting read image data in two colors, black and a color other than black. In such a digital copying apparatus, generally, the RGB read signals are processed in parallel, and the background removing apparatus that corrects the background density of an original to remove the background also corresponds to each of the three colors RGB. It is prepared.

However, when the background removing device is arranged corresponding to the three colors of RGB and the background removing device removes the background for each color, the operations of the background removing device vary, and therefore these operations are performed. When the two-color mode copy is performed, the gray balance is lost and the color detection does not work properly.

Therefore, in order to perform color detection with high accuracy,
As disclosed in Japanese Unexamined Patent Publication No. Hei 4-21266, "sensitivity adjusting device for digital scanner", by mounting a highly accurate AE mechanism, occurrence of change in copy image density can be prevented and color detection can be accurately performed. An apparatus for doing so is provided.

[0005]

However, according to the above-mentioned conventional technique, it is necessary to mount a high-precision AE mechanism, which causes a problem that the number of parts constituting the apparatus increases and an increase in cost. There was a problem to do.

The present invention has been made in view of the above circumstances, and an object of the present invention is to enable normal color detection without increasing the number of parts constituting the apparatus and increasing the cost.

[0007]

In order to achieve the above object, the present invention inputs an image reading means for optically reading an image of an original and image data read by the image reading means to obtain the background of the original. In a digital copying apparatus having a background removing unit that corrects the background density to remove the background and an image output unit that outputs the read image data in black and a color other than black, the original is copied in a single color When a single-color copy is specified via the specifying means for specifying whether to copy in color, the background removing means is operated to perform background removal, and multi-color copying is performed. When specified, the control means controls the operation of the background removing means so as not to perform the background removal.

[0008]

In the digital copying apparatus of the present invention, the background removing means is operated to remove the background when a single color copy is designated, and the background removing means is operated when a multicolor copy is designated. The operation of is prohibited and the background is not removed to prevent the gray balance from being disturbed when copying in multiple colors.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The following is a description of an embodiment of the digital copying apparatus of the present invention. Schematic configuration and operation of the digital copying apparatus of the present embodiment Overall configuration of image processing unit Configuration and operation of video processing circuit Configuration and operation of image processing circuit The operation in the two-color copy mode will be described in detail with reference to the drawings.

Schematic Configuration and Operation of Digital Copier of this Embodiment FIG. 1 shows a schematic diagram of the digital copier of this embodiment. This digital copying apparatus is roughly classified into a scanner unit 10
1 and a plotter section 111, and an operation panel 2 described later.
The necessary copying conditions are set by 01, and the scanner unit 1
When the copy start key on the operation panel 201 is pressed while the original is set on the contact glass 102 of No. 01, the scanner unit 101 causes the contact glass 102
Start scanning the image of the original document above.

That is, the first mirror 103 and the light source 104
The lower surface (image surface) of the original document placed on the contact glass 102 is optically scanned (scanned) by moving the traveling body 105 integrated with the other parts to the left in the figure. As a result, the reflected light image from the document surface is sequentially transferred to the first mirror 103, the second mirror 106, and the third mirror 10.
It is guided to the lens 108 via 7 and is imaged on the light receiving surface of the CCD color image sensor 109. The CC
The image data read by the D color image sensor 109 is output to the image processing unit 200 described below and subjected to image processing.

On the other hand, the plotter section 111 includes the image processing section 2
The image data processed in 00 is input to form an image on the transfer paper. That is, the photosensitive drum 112 is rotated in the direction of the arrow in the figure, and at the same time, the photosensitive drum 112 is rotated.
The charge removal lamp (QL) 116 and the pre-transfer charge removal lamp (P) are arranged so that the residual toner and the non-uniform potential attached on the top do not reach the charging charger 113 and the developing devices 114 and 115.
TL) 117, transfer charger 118, separation charger 119, eraser 120, and cleaning unit 1
21 is driven so that the surface potential of the photosensitive drum 112 after passing through the charge eliminating lamp 116 becomes substantially zero.

After that, the surface of the photosensitive drum 112 is uniformly charged by the charging charger 113, and laser light is emitted from a semiconductor laser 144a described later according to the black image data. Laser light emitted from the semiconductor laser 144a enters a polygon mirror (laser light generator) 122 that is focused by a cylinder lens (not shown) and rotationally scans, and the reflected light is reflected by the optical system (lens) 1.
The surface of the photosensitive drum 112 is irradiated with the light through the mirror 23 and the mirror 124 to form an electrostatic latent image.

Then, the latent image formed on the photosensitive drum 112 is removed by the eraser 120 from the electric charge of the non-image portion (the unnecessary portion protruding from the image forming area), and then black toner is attached by the black developing device 115. Visualize. At this time, the contrast of the image can be adjusted by changing the developing bias potential.

Next, the electrostatic latent image is formed again on the surface of the photosensitive drum 112 by the light emission from the LED array 140 according to the color image data, and the color toner is attached by the color developing device 114 to form a visible image. To do.

The formation of the electrostatic latent image of the color image with respect to the black image is adjusted by using a predetermined memory (not shown) because the image positions on the transfer paper do not match unless delayed by a predetermined time. is doing. This time is obtained by dividing the distance from the exposure position on the photosensitive drum 112 by the semiconductor laser to the exposure position by the LED array 140 by the rotation speed of the surface of the photosensitive drum.

On the other hand, one of the calling rollers 125, 126a, 162b and 126c is driven by turning on a paper feed clutch which can selectively take out the drive of a main motor (not shown), and a preselected paper feed stage (described later). Registration roller pair 1 that is stopping the transfer paper set in
The paper is fed toward 27.

A registration sensor 128 is arranged in front of the registration roller pair 127. This registration sensor 1
Reference numeral 28 denotes, for example, a reflection type photo sensor, which is turned on when the leading end of the transfer paper arrives at the facing position. After the registration sensor 128 is in the ON state and a certain period of time has elapsed, the paper feed clutch is returned to the OFF state to stop the transfer paper being conveyed.

The OFF timing of the paper feed clutch is set longer than the time during which the transfer paper is conveyed between the registration sensor 128 and the registration roller pair 127. Therefore, the leading edge of the transfer paper is the registration roller pair 127.
Wait until the tip side is bent and the skew is prevented to prevent skew. Then, the photosensitive drum 112
A registration clutch (not shown) is turned on at a timing aligned with the top of the black image, and the registration roller pair 127 is rotationally driven thereby, so that the standby transfer paper is re-conveyed toward the transfer section. .

When the transfer paper arrives at the transfer portion, the toner image on the photosensitive drum 112 is transferred onto the transfer paper by the action of the transfer charger 118, and then the separation charger 119 integrally held with the transfer charger 118. By the action, the charge potential on the paper surface is lowered to reduce the adhesion between the transfer paper and the photoconductor drum 112, and then the separation claw 129
The transfer paper is separated from the photoconductor surface by.

Then, the transfer paper is sent to the fixing unit by a conveyor belt 130 stretched by two rollers,
The toner image is thermally fixed by the fixing roller 131, and thereafter, if the single-sided mode is selected as the copy mode, the sheet is discharged to the external discharge tray 133 through the upper side of the switching claw 132, and if the double-sided mode is selected, the switching is performed. By switching the claw 132, the paper is fed to the lower re-feeding conveyance path.

The residual toner on the photosensitive drum 112 after the image transfer is the cleaning brush 121a constituting the cleaning unit 121, and the cleaning blade 1.
21b, the toner is recovered by the toner recovery tank 121c, and the photosensitive surface of the toner is exposed by the static elimination lamp 116 to erase the remaining charges.

By the way, in this copying apparatus, "red toner" and "blue toner" can be used as color toners, so that the operator can detachably replace the color developing device 114 for the toner of the required color. Has become.

Further, in this copying apparatus, three paper feed cassettes 134 to 136 in which transfer papers of different sizes are set are attachable / detachable as a normal paper feed cassette capable of accommodating only transfer papers of a specific size at a time. Transfer paper that is provided and is not stored in any of the paper cassettes,
That is, it also has a manual feed table (manual feed tray) 137 on which transfer paper of an unspecified size can be set.

When copying using the transfer paper stored in any of the paper feed cassettes 134 to 136, after selecting the cassette size by the size selection key on the operation panel 201, the copy start key By pressing, the transfer paper is fed from the paper feed cassette.

138a to 138c are size detection sensors for detecting the size of each paper stored in each of the paper feed cassettes 134 to 136. For example, five photo interrupters are used.

Overall Configuration of Image Processing Unit FIG. 2 is a block diagram showing a schematic configuration of the image processing unit 200 of this embodiment. The image processing unit 200 inputs a video processing circuit 141 for inputting analog signals of RGB read by the CCD color image sensor 109 and performing A / D conversion,
An image processing circuit 142 that performs image processing, and a plotter unit 11
1, a video writing processing circuit 143 that controls the semiconductor laser 144, an LD control unit 144 that controls the semiconductor laser 144a, and an LED.
An LED control unit 145 that controls the array 140, a CPU 146 that controls the entire apparatus, a ROM 147 that stores a control program, and a RAM 148 that is temporarily used by the control program. In addition,
In the figure, 151 is an address data bus, 152 is a system bus, and 201 is an operation panel for a user to set numerical values for input of various modes.

Further, as shown in the figure, the video processing circuit 141, the image processing circuit 142, and the video writing processing circuit 14 described above.
The CPU 3 shares an address bus / data bus with the CPU 146, and communication is performed via this. CPU1
Reference numeral 46 also controls the motors of the scanner unit 101 and plotter unit 111. In addition, it also controls various clutches and solenoids.

Configuration and Operation of Video Processing Circuit Next, the specific configuration and operation of the video processing circuit 141 will be described. FIG. 3 shows a part of the circuit configuration of the video processing circuit 141. CCD color image sensor 10
Reference numeral 9 divides the read RGB analog signals into odd-numbered pixels and even-numbered pixels and outputs them. This analog signal is pre-amplified by the amplifiers 301 and 302 and then converted into a DC level signal by the zero clamp circuits 303 and 304.

After that, the odd number pixel and the odd number pixel are combined into one channel by the plexer 305, and the light amount is corrected by the AGC (auto gain amplifier) 306 to obtain A /
It is input to the D converter 307.

The A / D converter 307 is configured to compare the Vref input from the Vref determining circuit 308 with the input V _IN and output the digital data Dw. Therefore, if the Vref determining circuit 308 changes Vref, the A / D conversion characteristic changes. In the figure,
Reference numeral 309 denotes a gain determination circuit that determines the gain D _AGC of the _AGC 306, and 310 and 311 denote ROM and RAM.

Next, referring to FIG. 4, the Vref determining circuit 3
The configuration of 08 will be described. Vref determination circuit 308
In the above, Vref is generated using the analog signal V. In the figure, in order to obtain the maximum value of Va = R4 / (R3 + R4) * V, in the peak hold circuit 401, Vb
= Va, max = R4 / (R3 + R4) * Vmax is detected.

After all, Vref is R4 / (R3 + R4)
* (R5 + R6) / R6 * Vmax = A * Vmax and V
The larger one of c and c is output, but the background removal mode O
In N (AE mode), since the AEMODE signal = H,
Since Tr2 is turned on, A * Vmax is generally selected.

The background removal is performed by the V determined in this way.
It operates by using ref as the reference voltage of the A / D converter 307. The analog signal of the read image is A / D converted by the A / D converter 307, and 8-bit digital data RD synchronized with a predetermined reference clock.
It is output as T0-7, GDT0-7, BDT0-7.

Although not shown, the video processing circuit 1
Reference numeral 41 denotes a shading correction circuit, which performs black offset correction, shading correction, and pixel position correction on each image data, and 8-bit digital data RDT0-7, GDT0-7, BDT0 synchronized with a reference clock.
Output as 7. Here, the black offset correction is C
This is a correction for subtracting the black level of the dark current of the CD color image sensor 109 from the image data. Further, the shading correction is performed by reading a white plate having a uniform density before starting the scanning of the original document in order to remove the unevenness of the light amount of the light source in the main scanning direction and the unevenness due to the difference in sensitivity between the pixels of the CCD color image sensor 109. Is stored for each pixel, and the correction is performed by dividing the image data during the reading of the document by the stored white plate data for each pixel. Further, the pixel position correction is to correct the pixel position shift in the sub-scanning direction when the CCD color image sensor 109 having three lines is used.

Configuration and Operation of Image Processing Circuit FIG. 5 is a block diagram showing a schematic configuration of the image processing circuit 142. In the image processing circuit 142, the color separation circuit 501 first performs color separation of black data and red data from RGB signals. Here, when separating red, RG is calculated and red data is generated when it is larger than a predetermined value.

The 8-bit black data BLK0 to 7 and the 1-bit red data output from the color separation circuit 501 are MT
In the F correction circuit 502 or the binarization circuit 503,
After being corrected or binarized, the scaling circuit 504
Then, electrical scaling in the main scanning direction is performed, γ correction is performed by the γ correction circuit 505, and finally image quality processing such as dither and error diffusion is performed by the image quality processing circuit 506. The MTF correction is to correct optical frequency characteristic deterioration and the like with a two-dimensional spatial filter.

The black data BLKDT0-7 and REDDT on which the various corrections have been performed in this way are stored in the video writing processing circuit 1.
Sent to 43.

On the other hand, the video writing processing circuit 143 performs speed conversion to the writing speed of the plotter section 111. Also, L
The D control unit 144 controls the pulse width and the amount of current supplied to the semiconductor laser 144a according to the 8-bit 256-gradation image data to control the semiconductor laser 14a.
The light emission amount of 4a is controlled to control the density of the black output image.

The LED control unit 145 is red (or blue)
The image writing control unit controls the light emission of the LED array 140. The LED array 140 is a combination of 2400 LEDs arranged in the longitudinal direction and a SELFOC lens for condensing, and constitutes a small writing system, although the resolution and gradation are lower than those of the laser writing system. can do. As a result, in this embodiment, red (or blue) writing is performed.

Operation in Two-Color Copy Mode In the digital copying apparatus of this embodiment, the black and white copy mode in which the light and shade of the original is printed in black and white and the red (or blue) portion of the original is set to red ( It has two modes, a two-color copy mode for outputting in blue).

In the character original mode in the normal black-and-white copy mode, it is desirable that only the characters are clearly output without producing the background, so that the background removal mode ON (AEMODE signal = H) is set by the CPU 146 as the default. It is set in the circuit 141. At this time, the image processing circuit 142 is set by the CPU 146 in the monochrome character mode (the color separation circuit 501 does not perform color separation and does not output a color signal, and the filter is for character mode). In this state, the copying operation by the digital copying apparatus is performed.

In the above-described operation, the color separation circuit 501 mixes the RGB read signals at a certain ratio to obtain 8-bit black data. Therefore, the RGB removal signals are slightly different due to variations in the background removal circuits of the RGB channels. It is not a problem that the output data is out of balance.

On the other hand, in the character original mode in the two-color copy mode, the background removal mode OFF (AEMODE signal = L) is set to the CPU by default for the video processing circuit 141.
146. This is the background removal mode ON
If this is set, the balance of the RGB output data is slightly disturbed due to variations in the background removal circuit of each RGB channel, and the read image is colored, and the color separation circuit 5
This is because the number of malfunctions of 01 may increase. Also,
In the image processing circuit 142, the two-color character mode is set by the CPU 146 (color separation is performed by the color separation circuit 501,
The filter is for character mode).

In this embodiment, by selecting the two-color copy mode from the operation panel 201 in this way, the background removal circuit is automatically turned off. Therefore, color separation failure due to variations in the RGB background removal circuit (ie, (Color detection failure) can be avoided.

As described above, in this embodiment, color detection can be normally performed without providing a special mechanism.
In other words, color detection can be normally performed without increasing the number of parts constituting the device and increasing the cost.

[0047]

As described above, in the digital copying apparatus of the present invention, when copying in a single color is designated, the background removing means is operated to remove the background, and copying in multiple colors is designated. In this case, the operation of the background removing means is prohibited so that the background removal is not performed, and the gray balance is prevented from being destroyed when copying in multiple colors. Therefore, the number of parts constituting the apparatus is increased and the cost is increased. The color detection can be performed normally without causing the

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a digital copying apparatus of this embodiment.

FIG. 2 is a block diagram showing a schematic configuration of an image processing unit of the present embodiment.

FIG. 3 is an explanatory diagram showing a part of the circuit configuration of a video processing circuit.

FIG. 4 is an explanatory diagram showing a configuration of a Vref determination circuit.

5 is a block diagram showing a schematic configuration of the image processing circuit of FIG.

[Explanation of symbols]

 200 image processing unit 141 video processing circuit 142 image processing circuit 143 video writing processing circuit 144 LD control unit 144a semiconductor laser 145 LED control unit 140 LED array 201 operation panel 501 color separation circuit

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁶ Identification number Internal reference number FI Technical display location G06T 1/00 H04N 1/46 H04N 1/46 C (72) Inventor Yoshiyuki Hatsuka Nakata, Ota-ku, Tokyo Magome 1-chome 3-6 in Ricoh Co., Ltd. (72) Inventor Anrō Ha, 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd. (72) Goji Tone 1-chome, Nakamagome, Ota-ku, Tokyo No. 3-6 In Ricoh Co., Ltd.

Claims (1)

[Claims] 1. An image reading unit for optically reading a document image, a background removing unit for inputting image data read by the image reading unit, and correcting the background density of the document to remove the background, and the reading unit. In a digital copying apparatus having an image output means for outputting the image data in black and a color other than black, a designation means for designating whether the original is copied in a single color or in a multicolor, and the designation means When the copying in a single color is designated, the background removing means is operated to perform the background removal, and when the copying in a multicolor is designated, the operation of the background removing means is prohibited. A digital copying apparatus comprising: a control unit that controls so as not to remove the background.