JPH0364773A - Color copying device - Google Patents

Abstract

PURPOSE:To shorten the time required for prescanning by stopping prescanning the instant an original is decided as being colored when scanning is performed to decide whether the original is black/white or colored. CONSTITUTION:It is assumed that the original A is placed on an original platen glass and has a color area B at the top in that state. For instance, when color information is judged to be in a sub-operating position DP of the original A, decision scanning is stopped to take a full-color copy. Whereas no color information is detected even by scanning the trailing edge YE of the original, the original is judged to be black/white to take a monochromic black copy. In such a way, prescanning is stopped the instant that the original A is colored, and instantaneously a color copy is taken, thereby shortening the time required for prescanning.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a color copying apparatus, and particularly to a color copying apparatus having a function of automatically determining whether a document is a monochrome document or a color document.

[Conventional technology]

Conventionally, color copying machines automatically determine whether a scanned original is a black-and-white or color original, perform black monochrome copying for a black-and-white original, and use four colors of yellow, magenta, cyan, and black for a color original. Techniques for performing copying are known. This makes it possible to shorten copy time and reduce costs.

[Problem that the invention is trying to solve]

However, in the past, when performing black monochrome copying or color copying based on the determination result obtained by bliscanning the original image, the entire document area was bliscanned. When processing many manuscripts, the time required for bliscanning was large and inefficient.

[Means to solve problems]

The present invention has been made in view of the above-mentioned drawbacks, and the present invention reduces the time required for prescanning by stopping prescanning when it is determined that the original is a color original when scanning the original to determine whether it is black and white or color. It is intended to be shortened.

〔Example〕

Hereinafter, the present invention will be explained based on examples.

FIG. 2 shows an overall configuration diagram of a digital color copying machine.

An image scanner unit 201 reads a document and performs digital signal processing. A printer section 202 prints out an image corresponding to the original image read by the image scanner section 201 on paper in full color.

In the image scanner unit 201, 200 is a mirror pressure plate, and an original 204 on an original platen glass (hereinafter referred to as platen) 203 is irradiated with a lamp 205, and mirrors 206, 2
07.208, an image is formed on a 3-line sensor (hereinafter referred to as CCD) 210 by a lens 209, and full color information red (R), green (G), blue (B) lf
It is sent to the signal processing unit 211 as the f1 minute. In addition, 205
．． 206 is the velocity V, 207.208 is 1/2 v
The entire surface of the document is scanned by mechanically moving in a direction perpendicular to the electrical scanning direction of the line sensor.

The signal processing unit 211 electrically processes the read signals to produce magenta (M), cyan (C), and yellow (Y) signals.

The printer unit 202 decomposes black (Bk) into each component.
send to Furthermore, for each document scan by the image scanner section 201, one of M, C, Y, and Bk components is sent to the printer section 202, and one printout is completed by scanning the document four times in total.

M sent from the image scanner unit 201.

The C, Y or Bk image signal is sent to the laser driver 212. The laser driver 212 modulates and drives the semiconductor laser 213 according to the image signal. The laser beam is transmitted through a polygon mirror 214. f-theta lens 215. A photosensitive drum 217 is scanned through a mirror 216.

Reference numeral 218 denotes a rotary developing device, which includes a magenta developing section 219, a cyan developing section 220. Yellow developing section 221. It is composed of a black developing section 222, and four developing devices alternately contact the photosensitive drum 217 to develop an electrostatic latent image formed on the photosensitive drum 217 with toner.

223 is a transfer drum, and paper cassette 224 or 225
The paper fed from the transfer drum 223 is wound around the transfer drum 223, and the image developed on the photosensitive drum 217 is transferred onto the paper.

After the four colors M, C, Y, and Bk are sequentially transferred in this manner, the paper passes through the fixing unit 226 and is discharged.

In the RDF (circulating document feeder) 230, 23
Reference numeral 1 denotes a stacking tray on which documents are set. Document size detection sensors 232 and 233 are provided at a predetermined interval in a direction perpendicular to the paper surface of the document. The size of the document in the width direction depends on whether both sensors 232 and 233 are detecting the document, or only one sensor 233 (assuming that sensor 233 is located on the back side of the paper) is detecting the document. This can be determined by checking whether there are any. In addition,
By increasing the number of sensors of this type, more accurate size determinations can be made. Also, the size in the length direction is the sensor 23
3 (or 232) can be determined based on the time during which the document is being detected.

In addition, in this RDF 230, the document sent from the stacking tray 231 to the exposure surface through the sheet path 234 is sent through the sheet bus 235, and then returned to the stacking tray 230.
It can be loaded onto. Further, 237 is a sensor that detects one cycle of the document.

FIG. 1 shows a block diagram of a color copying apparatus to which the present invention is applied, and will be described below.

The CCD reading section 101 has R (red) and G (green).
, B (blue) analog color signals, an amplifier for amplifying each color, and an A/D converter for converting into an 8-bit digital signal. The signal subjected to shading correction for each color in the shading correction unit 102 is corrected for deviations between 9 pixels between colors in the shift memory unit 103, and then processed by the color judgment unit 112 (described later) and LOG conversion that performs logarithmic correction for light/density conversion. Part 1
Sent to 04.

Density signals Y (yellow), 1M (magenta), and C (cyan), which are output from the LOG converter 104, are input to a black generator 105, and a black signal (Bk) is generated. Bk is generated from, for example, Min (Y, M, C). Furthermore, in the masking/UCR section 106, the output Y of the black production section 105 is
, M, C, and Bk signals, the filter characteristics and toner density characteristics of the color sensor are corrected, and after the undercolor is removed, one color to be developed is selected from among the four color signals.

Next, in a density converting section 107, the density is converted according to the development characteristics of the printer and the operator's preference, and then in a trimming processing section 108, a desired section is edited and sent to a printer section, where an image is formed.

A synchronization signal generation unit 109 generates horizontal synchronization used inside the image scanner based on a horizontal synchronization signal BD (Beam Detect) signal and a vertical synchronization signal ITOP (Image Top) signal synchronized with the printing of each line sent from the printer. The signal H3YNC, pixel synchronization signal CLK, etc. are generated and sent to each processing unit and CPU.

The document position detection unit 110 detects the position and size of the document based on the binary SC signal of the green (G) signal that has undergone shading correction. Further, the scaling/movement processing unit 111 realizes scaling and movement of the image by controlling the cycle and timing of reading and writing data to the shift memory.

The CPU section 113 includes, in addition to a microprocessor, an I10 circuit, a timer circuit 1 interrupt control circuit, a serial communication circuit, a ROM, a RAM, etc., and controls each of the aforementioned processing sections.

The CPU section 113 also includes a pulse motor 114 for driving the optical system, a document illumination lamp 115, and a pulse motor 114 for driving the optical system. A sensor 116 for detecting the position of the optical system. Control the operations department. Also RDF
It performs serial communication with 230 to control the operation of RDF.

The contents of the color determination section (112 in FIG. 1) are shown in FIG. 3A and will be described below.

The R, G, and B signal components for a certain pixel read out from the shift memory section 103 are input to the maximum value detection circuit 301 and the minimum value detection circuit 302, and from each circuit MAX=
max (R, G, B), MIN=min (R, G,
B) is output. In this example, each color of R, G, and B is 8b.
An output of 6 bits each for MAX and MIN is obtained for the input of it. Next, MAX and MIN are both input as addresses of the lookup table LUT303, and the result is 1
Obtain the bit color determination signal IRQ.

FIG. 3(B) shows the contents of the LUT 303. Input MAX
.

In a two-dimensional plane composed of
The determination signal IRQ thus obtained is input as a clock to the counter 304.

The counter 304 is reset by the horizontal synchronizing signal H8YNC, and counts the number of chromatic color determination pixels of the determination signal IRQ within the interval permitted by the GATEA signal, which is the output of the flip-flop 306 in one main scanning line. This count value is read out by the CPU 113 via the latch 305.

Flip-flop 306 is set by the count-up signal of ST counter (start bit counter) 309 and reset by the count-up signal of EN counter (end bit counter) 310, and generates count permission signal GATE for counter 304. ST counter 309 and E
The N counters 310 count down the count values written in the latches 307 and 308 by the CPU 113, respectively.

As described above, the number of chromatic color determination pixels in an arbitrary section of each main scanning line can be counted.

FIG. 4 shows a conceptual diagram of the first embodiment and will be described below.

(4-1) shows a state in which the original A is placed on the original platen glass 203. It is assumed that the document A has a colored area B toward the leading edge when it is placed. Conventionally, even if the position coordinates of document A were known, a determination scan was performed over the entire document area as shown in (4-4), but as shown in (4-3), Position DP
When it is determined that there is color information in the document A, the determination scan is stopped and full-color copying is performed, and the scanning time corresponding to the dotted line C is shortened.

On the other hand, as shown in (4-2), if color information cannot be detected even after scanning to the end of the document YE, it is determined that the document is black and white, and black monochrome copying is performed.

FIG. 5 shows the control procedure of the first embodiment and will be described below.

First, the ST counter 309 in FIG. EN counter 31
Set the main scanning coordinates XS and XE of the original as the load value of 0 (501), initialize the counter K on the RAM as an integration counter for the number of chromatic pixels detected in Fig. 3 with O (502), and turn on the lamp. lights up and starts the optical system (
503). Then, when the optical system reaches the sub-scanning leading edge position YS of the document (504), the CPU sends a horizontal synchronizing signal HSY.
When an NC interrupt occurs (505), the count value of the number of chromatic pixels by the counter 304 in FIG. 3 is read via the latch 305 and added to the integration counter K (506).

When the additional value K becomes larger than the predetermined value α (507), it is determined that the document is a color document, and at that point the lamp is turned off, the optical system is returned to the starting point (511), and a color copy is executed (512). ). On the other hand, if the additional value K is smaller than α in (507), it is determined whether the document end YE has been reached (508), and if it has not been reached (505), the following processing is repeated.

Even if YE is reached (508), if K is smaller than α, the lamp is turned off, the optical system is restored (509), and then black monochrome copying is executed.

As described above, it is possible to automatically determine that the document is a color original, and to shorten the prescan time required for determination when performing color copying.

For example, when scanning an A3 document forward at 160 mm/sec and backward at twice that speed, the maximum
This will save you nearly a second.

While the first embodiment is effective when applied to cases where the document position is known in advance, the second embodiment is effective when applied to cases where the document position is known in advance. By simultaneously detecting the document position, the prescan time is further reduced.

FIG. 6 shows and explains the concept of the second embodiment.

As shown in (6-4), first a scan is performed to detect the position of the document across the entire platen, then a scan is performed to determine whether the detected document area is in color or black and white, and then color copying is performed. , or monochromatic black copying, the pre-scanning before color copying takes a very long time. Therefore, in the second embodiment, as shown in (6-3), a judgment scan is performed while detecting the document position and judging the document color at the same time, and the prescan is stopped when it is judged that there is color information. Make a color copy.

Furthermore, in the case of a black and white original, as shown in (6-2), prescanning is stopped when it is detected that the original A is interrupted before color information is detected, and then black monochrome copying is executed.

The configuration for realizing the operation shown in FIG. 6 will be explained below.

First, the concept of document coordinate detection, which is essential for realizing the second embodiment, will be described.

As described above, the pressure plate 200 is mirror-finished, and the reflected light obtained by illuminating the pressure plate is specularly reflected and is not focused on the image reading sensor, resulting in a black level in terms of brightness.

Further, the background of a normal original is white, and its image signal has a white level in terms of brightness.

Therefore, as shown in FIG. 7, the position of the document placed on the platen can be detected by detecting the position of the white signal among the black signals shown in the shaded area.

In this embodiment, the optical system points the reference point SP on the platen.
The main scanning positions XS and XE of the document at an arbitrary sub-scanning position Yi are detected while scanning in the A direction from to the rear end EP.

FIG. 8 shows the logic for detecting the coordinates and will be described below.

The main scanning counter 401 is an up counter and is a main scanning 1
Represents the scanning position within the line. This counter is reset by the horizontal synchronizing signal HSYNC, and counts up every time the image data clock CLK is input. Image data VIDEO, which is a binarized G (green) signal after shading correction, is input to the shift register 402 in units of 8 bits. When the 8-bit input is completed, the gate circuit 403 checks whether all 8 bits are a white image, and if YES, outputs "1" to the signal line 411.

Flip-flop 410 is set when the first 8-bit white appears in each main scan line. This flip-flop 410 is reset in advance by the H3YNC signal.

From now on, the H3YNC of the law will remain set until it comes. If the EN signal output by the CPU is "1" when the flip-flop 410 is set, the gate 404 outputs "L", so the latch 409 stores the main scanning counter 40 at that time.
A value of 1 is loaded, and this becomes the X coordinate value.

Further, each time the gate 403 outputs 1, the value of the main scanning counter 401 is loaded into the latch 405.

When the value from the main scanning counter when the first 8-bit white appears is loaded into the latch 405, it is compared in magnitude with the data in the latch 408 by the comparator 406.
The data is larger and the signal EN output by the CPU is 1.
The data in latch 405 is loaded into latch 408 when . This operation is processed until the next 8-bit VIDEO enters the shift register 402.

If this comparison operation between the latches 405 and 408 is continued during one main scanning line, the main scanning coordinate where the last 8-bit white appears in the main scanning direction remains in the latch 408, and this becomes the xE coordinate value.

FIG. 9 shows an example of a timing diagram related to coordinate detection. The horizontal synchronizing signal H3YNC(1) also corresponds to the effective section of the image, that is, in this case, the main scanning section of the platen. The configuration is such that an interrupt signal lNTl (2) is generated to the CPU 113 at each falling edge of H3YNC (1). The CPU 113 moves the optical system in the sub-scanning direction, and when it detects that it has reached the reference point SP (5), the EN
Turn on signal (3). The detection circuit shown in FIG. 4 performs the detection operation in units of HSYNC intervals during the ON interval of the EN signal.

On the other hand, when the CPU 113 turns on the EN signal (3),
5YNC interrupt lNTl is counted twice and the EN signal is turned off. This is because the ON timing of the EN signal is H3.
This is because there is no guarantee of synchronization with YNC, and correct detection over the entire main scanning period cannot be performed in P(4), which is the detection period from the EN signal ON to the first interrupt lNTl. E
The coordinate values X, . . . After taking in the detected coordinates, turn on the EN signal, wait for the next lNTl, and repeat from then on.

With the above configuration and control, any sub-scanning position Yi
The main scanning section of the document in X S r x! : can be detected.

FIG. 10 shows the control procedure of the second embodiment and will be described below.

First, a counter K on the RAM as an accumulation counter for the number of chromatic pixels is initialized to 0, and a counter L on the RAM as a continuous line counter for an undetected area of the original is also initialized to 0 (701). Next, the judgment interval signal GA described in FIG.
Set the load values of the two counters ST counter and EN counter for TE generation to a value larger than l main scanning period so that the GATE signal is not output, and set the flag F on the RAM to 0 as a flag indicating the state. Te(
(702). Turn on the illumination lamp and start moving the optical system (703), and when it reaches the platen reference point SP (
704), turns on the aforementioned EN signal (705),
After that, the interrupt signal lN due to the falling edge of H3YNC
After waiting for the second Tl (706), the EN signal is turned off (707).

When the flag F indicating the control state of the GATE signal in the previous interrupt processing is 1 (708), that is, if a sample valid period is set, the count value of the counter 304 in FIG. The number of read chromatic pixels is added to the addition counter K (709). When K is larger than a predetermined value α (710), the briscan is stopped, the lamp is turned off, and the optical system is returned to the starting point (710).
20), execute color copying (721).

If F is O in (708), it means that the counting operation is not being performed and the count value is not read.

Next, the document positions xs and xE are immediately determined by the two latches 409 and 408 in the document position detection circuit shown in FIG.
11), when X, -Xs is larger than the predetermined value β (712
), XS and EN are set as the ST counter load value as the next chromatic pixel counting period assuming that the document has been detected.
x): is set as the load value of the counter, and the aforementioned flag F is set to 1 (713).

Further, a counter L is set to 1 to indicate that the document has been detected at least once. If XE -
Set a value thicker than the main scanning section and set flag F to O ((715).

When the document cannot be detected, the counter L is checked (716), and when L is O, no document has been detected yet, so the value of the counter L is left as is.

If L is not 0, increment L by 1 assuming that the document is missing after being detected at least once (717), and when the value of L becomes larger than the predetermined value γ (718), It is determined that the manuscript is no longer available.

Comparison with a predetermined value γ is one of the simplest noise removal methods.

At (718), when there are no more originals, Blisscan is stopped, the lamp is turned off, and the optical system is restored (718).
20), execute black monochrome copy (722).

If the process from (705) to (718) is repeated until reaching the platen end EP, the loop is not removed (719)
), if L remains O, it is assumed that there is no original, the lamp turns off, the optical system returns, and the process ends without copying.72
0), and if L is other than O, a single black copy is performed (722).

Shading correction unit 1 which is an image signal for document position detection
The output image signal G2 of 02 and the output image signals R3, G3°R3 of the shift memory section 103, which are image signals for color determination, are controlled in the shift memory section 103 so that G2 is faster by two lines. Two lines after setting the document section detected from R3°G3. By reading the chromatic pixel count based on R3, the document position and the chromatic determination section match.

Even if the document position is not known in advance as described above, the document color is determined based on the information in the document area, and prescanning is stopped when it is determined that the document is a color document or when there is no document left. Pre-scan time can be shortened.

〔Effect of the invention〕

As explained above, copying time can be shortened by canceling Briscan and immediately performing a color copy when it is determined that the original is in color.

Furthermore, even if the position of the original is not known in advance, it is possible to prevent unnecessary work such as scanning an area where the original does not exist to determine the original color, further reducing the copying time.

[Brief explanation of drawings]

Fig. 1 is a block diagram of a color copying apparatus according to the present invention, Fig. 2 is a sectional view of the color copying apparatus, Fig. 3(A) is a logic diagram of the color judgment section, and Fig. 3(B) is a color judgment table diagram. Figure 4 is an explanatory diagram of the first embodiment, Figure 5 is a control flowchart diagram of the first embodiment, Figures 6 and 7 are explanatory diagrams of the second embodiment, and Figure 8 is an explanatory diagram of the second embodiment. 9 is a timing chart related to document position detection, and FIG. 10 is a control flowchart of the second embodiment, 101 is a COD reading section, 112 is a color determination section, and 113 is a logic diagram of the document position detection section. C
The PU section 108 is a trimming processing section. 4th darkness (4-3') (4-4) 6th group (1,-3) (6-4) Figure 4 (,!;-7) ((,,-z)

Claims (2)

[Claims] (1) Prior to the copying operation, there is a means for preliminarily scanning the document surface to determine whether the document area is in color or black and white, and the preliminary scanning is terminated when the determining means determines that the document is a color document. A color copying device characterized by shifting to a color copying operation. (2) In claim 1, there is provided a means for detecting main scanning coordinates of a document at an arbitrary sub-scanning position, and a determining means based on detected coordinates sequentially detected by the detecting means during the preliminary scanning. 1. A color copying apparatus, comprising a control means for performing sequential control, and when a determination result by the determination means and a detection result by the detection means satisfy a predetermined condition, preliminary scanning is stopped and the copying operation is started.