JPH07147640A - Image processor - Google Patents

Abstract

PURPOSE:To reduce the deterioration of picture quality at the time of high- definition image recording by selecting a pulse width modulate signal corresponding to an optimum pattern signal by switching the pulse width modulate signal generated by pattern signals in different periods. CONSTITUTION:Concerning a synchronizing clock 2VCLK703 at the double, frequency of a VCLK701, one is a triangular wave WV1 generated by a triangular wave generating circuit 608 according to a reference signal 706 for triangular wave generation with a frequency halved by a J-K flip-flop 606, and the other is a triangular wave WV2 generated by a triangular wave generating circuit 609 according to a signal 707 prepared by dividing the frequency of 2VCLK into six with a six-frequency dividing circuit 605. With this operation, the signals of pulse width can be provided corresponding to the value of input VIDEO DATA 700 at outputs 710 and 711 of CMP1 610 and CMP2 611. When PW1 is selected, resolution is improved about three times is comparison with PW2 and when PW2 is selected, the dynamic range of pulse width is widened about three times in comparison with PW1 so that gradations can be improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image processing device.

[0002]

2. Description of the Related Art Conventionally, in a copying system of a color copying machine, an original is separated into three primary colors of B, G and R and inputted, and a copied image is formed by using complementary color-converted color materials of Y, M and C. . Toner, ink, etc. were used as the color material. The copying process includes electrophotography, thermal transfer, ink jet and the like.

[0003]

However, in any copying process, since the color images are formed by sequentially superposing each color material for each separation color, color misregistration occurs especially in copying fine lines such as black characters. It occurs and black becomes a color cod and becomes very difficult to see. In addition, in digital copying machines that have been developed in recent years, it is attempting to improve the quality of black characters by techniques such as black extraction, UCR, and edge tension, but it is not perfect yet, and as a harmful effect, In copying a document containing a mixture of photographs, noise is generated in the photograph portion due to edge emphasis, which deteriorates the quality of the image. In order to avoid this, it is considered to perform optimal processing for the edge part and the halftone part by separating the image area, but it is not yet complete.

Further, in the processing method such as the conventional dither method in the halftone processing, the processing capable of sufficiently enhancing both the resolution and the gradation is not yet known.

Therefore, an object of the present invention is to provide an image processing apparatus capable of solving the conventional problems.

[0006]

An image processing apparatus according to the present invention is an image processing apparatus having a multi-color copying mode and a single-color copying mode, and a specifying means for specifying the multi-color copying mode and the single-color copying mode. And a resolution switching means for increasing the recording resolution in the copying mode as compared with the multi-color copying mode.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the drawings.

FIG. 1 shows an example of a schematic internal configuration of a digital color image processing system according to the present invention. As shown in the figure, this system has a digital color image reading device (hereinafter, referred to as a color reader) 1 in the upper part and a digital color image printing device (hereinafter, referred to as a color printer) 2 in the lower part. The color reader 1 reads color image information of a document for each color by a color separation means described later and a photoelectric conversion element such as a CCD, and converts the color image information into an electric digital image signal. In addition, the color printer 2
This is an electrophotographic laser beam color printer that reproduces a color image for each color according to the digital image signal, transfers the color image to a recording paper a plurality of times in a digital dot form, and records the image.

First, the outline of the color reader 1 will be described. Reference numeral 3 is a document, and 4 is a document scanning unit for scanning the document 3. The original scanning unit 4 includes a rod array lens 5, a unity color separation line sensor (color image sensor) 6 and an exposure lamp 7. 8 is a wiring code of the document scanning unit 4, 9 is a cooling fan, and 10 is a cooling fan.
Is an image processing unit connected to the document scanning unit 4 through the wiring cord 8.

When the original scanning unit 4 moves and scans in the direction of arrow A in the figure by the scanner driving motor 49 to read the image of the original 3 on the original table, at the same time, the exposure lamp 7 in the original scanning unit 4 is turned on and the original is scanned. Reflected light from 3 is guided by a rod array lens 5 and is condensed on a unit color separation line sensor 6 which is a color information reading sensor.

Reference numeral 21 is an actuator provided below the original scanning unit 4, and 22-1 and 22-2 are position sensors for detecting the scanning position of the original scanning unit 4 via the actuator 21, and are provided by a photo interrupter or the like. Become.

Next, an outline of the color printer 2 will be described. A scanner 11 includes a laser output unit (see FIG. 6) for converting an image signal from the color reader 1 into an optical signal, a polygon mirror 12 having a polyhedron (for example, octahedron),
It has a motor (not shown) for rotating the mirror 12, an f / θ lens (imaging lens) 13 and the like. Reference numeral 14 is a reflecting mirror that changes the optical path of the laser light, and 15 is a photosensitive drum. The laser light emitted from the laser output unit is reflected by the polygon mirror 12, passes through the lens 13 and the mirror 14, and linearly scans the surface of the photosensitive drum 15 (raster scan) to form a latent image corresponding to the original image. .

Further, 17 is a primary charger, 18 is a full-surface exposure lamp, 23 is a cleaner section for collecting the untransferred residual toner, 24 is a pre-transfer charger, and these members are provided around the photosensitive drum 15. It is arranged.

Reference numeral 26 is a developing device unit for developing the electrostatic latent image formed on the surface of the photosensitive drum 15 by laser exposure, and 31Y, 31M, 31C and 31BK are in direct contact with the photosensitive drum 15 for direct development. Development sleeve, 3
Reference numerals 0Y, 30M, 30C, and 30BK denote toner hoppers for holding the preliminary toner, 32 denotes a screw for transferring the developer, and these sleeves 31Y to 31B.
K, the toner hoppers 30Y to 30BK, and the screw 32 constitute a developing device unit 26, and these members are arranged around the rotation axis P of the developing device unit. 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 26 is rotated about the axis P in the figure to expose the toner image. The developing sleeve 31M in the magenta developing device is arranged at a position in contact with the body 15. Cyan and black development work similarly. The rotational movement of the developing device is performed by a motor 530.

Further, 16 is a transfer drum for transferring the toner image formed on the photosensitive drum 15 onto a sheet, 19 is an actuator plate for detecting the moving position of the transfer drum 16, and 20 is this actuator plate 19. A position sensor for detecting that the transfer drum 16 has moved to the home position due to the proximity, 25 is a transfer drum cleaner, 27 is a paper pressing roller, 28 is a static eliminator, and 29 is a transfer charger. , 20, 2
5, 27 and 29 are arranged around the transfer roller 16.

On the other hand, 35 and 36 are paper feed cassettes for storing paper sheets (leaflets), 37 and 38 are paper feed rollers for feeding paper from the cassettes 35 and 36, and 39, 40 and 41 are paper feed and transport. Is a timing roller that takes the timing of, and the paper fed and conveyed through these is a paper guide 4
The tip of the gripper is guided by 9 and will be described later (see 51 in FIG. 7).
While being carried by the sheet, the sheet is wound around the transfer drum 16 and the image forming process is started.

A drum rotation motor 550 synchronously rotates the photosensitive drum 15 and the transfer drum 16. 50 is a peeling claw for removing the paper from the transfer drum 16 after the image forming process is completed, 42 is a conveyor belt for conveying the removed paper, and 43 is an image fixing unit for fixing the paper conveyed by the conveyor belt 42. The image fixing section 43 has a pair of thermal pressure rollers 44 and 45.

First, with reference to the block diagram of FIG. 2, a portion related to the present invention in the overall configuration of the electric circuit of the embodiment will be described.

The reader 1 and the printer 2 have a CPU 69,
A controller 74 including a ROM 71, a RAM 72, an I / O port 73, and a CPU bus 70 connecting them.
Controlled by. CPU 69 is serial communication line 2
It communicates with the operation unit 67 and the digitizer 68 via 40 and receives a command from the operator. From the digitizer 68, coordinate information relating to editing of a document to be copied, such as area designation information and area moving position information, is input. Operation unit 67
In addition to the normal number of copies and the scaling factor, designated areas and reproduction mode information outside the designated areas, such as multicolor, single color, gradation conversion characteristics, resolution, and color conversion mode, are input.

The controller 74 also sends a scaling mode signal to the driver 61 of the scanner drive motor 49 (stepping motor) for controlling the movement of the document scanning unit 4 of the reader 1 via lines 237 and 238, respectively.
Further, a movement control signal is given to control the movement direction, speed and position of the document scanning unit 4. A stepping motor pulse is input from the stepping motor driver 61 to the interrupt terminal INT of the CPU 69 via the line 236, and is counted as position information of the document scanning unit 4.

Further, the detection signal of the home position sensor (SR1) 22 when the original scanning unit 4 is in the copying pause is input through the line 242. The controller 74 also gives an ON / OFF command to the motor driver 62 of the drum drive motor 550 of the printer 2 via the line 239.

The drum drive motor 550 comprises a combination of a DC motor and a rotary encoder (E) and is speed controlled by a PLL control circuit in the motor driver 62. Further, the detection signal of the home position sensor (SP1) 20 of the transfer drum 16 is input to the controller 74 via the line 243. Further, the controller 74 turns on / off the control circuit 63 of the exposure lamp 7 via the line 241.
Give an OFF command. The lamp control circuit 63 also controls the constant voltage of the exposure lamp 7.

The laser beam output from the laser scanner 11 is detected by the BD detection circuit 52 for each scanning of the photosensitive drum 15 to generate a BD signal. The BD signal is input to the synchronizing signal generation circuit 82 via the line 226, and the copy interval signal input from the controller 74 via the line 235 or the counter set signal, the mode select signal and the video signal input via the line 234. H which is a video synchronization signal together with the clock VCLK of
SYNC, V.I. ENABLE, R.A. V. ENABLE,
P. V. Generate ENABLE. The synchronization signal generation circuit 82 also outputs a laser control signal via a line 232 in response to a laser OFF (LOFF) signal input from the controller 74 via a line 233 at the same time.

Here, the operation of the synchronizing signal generating circuit 82 will be described with reference to FIGS. Copy section signal 4
Reference numeral 50 generates a synchronizing signal at "H" during the copying operation, and further controls the entire operation in which the laser is turned off. When the copy interval signal 450 becomes "H", the J / K-FF402 is cleared and the rising edge of BD is VC at DF / F401.
J / K-FF 402, 403, 40 synchronized with LK
Input to 5. J / K-FF402AND417 is B
HSYNC is generated from the VCLK1 cycle immediately after the D is generated, and at the same time, VSYNC is synchronized with the falling edge of HSYNC. Start ENABLE (J / K-FF402Q is "H"). As a result, the load (L) of the counter 407 is released. Here, SET1 to SET5 are counter set signals input from the controller 74 and serve as count data of the counters 407 to 411. When the load (L) of the counter 407 is released, the counter 407 counts the value by SET1, outputs RC at the time of counting up, resets the J / K-FF 402, and resets the V.V. ENABLE ends.

Next, the J / K-FF 403 is a V. ENABL
At the same time when E rises, the load of the counter 408 is released and the counter 408 counts the value by SET2.
RC is output by counting up and J / K-FF403
The J / K-FF 412 is set at the same time when is reset. At the same time, the J / K-FF 404 is set and the load of the counter 409 is released.
The value of 3 is counted, RC is output by the count-up, J / K-FF404 is reset, and J / K-FF4
12 is reset.

As described above, the J / K-FF 412 is a V. EN
The left margin is set by SET2 from the rise of ABLE, and it is reset after the effective section by SET3 is completed. The Q output of the J / K-FF 412 is D. ENA
It is input to the selector 414 together with BLE and is selected by the mode select signal 463. V. It becomes an ENABLE signal.

Similarly, the J / K-FF 413 is a V. ENAB
The left margin is set by SET4 from the rise of LE, and it is reset after the valid section by SET5 is completed. The Q output of the J / K-FF 413 is V.V. ENABL
It is input to the selector 415 together with E and P.P. V. It becomes an ENABLE signal.
The Q output of the J / K-FF413 is V.V. The mode select signal 465 is input to the selector 416 together with ENABLE.
Becomes a laser control signal. The laser control signal is gated to LOFF by the AND 417 and is under the laser off control of the controller 74.

R. V. ENABLE, P.I. V. ENAB
LE is input to the synchronous memory circuit via line 231 and determines the video effective section of the main scanning direction of the reader and printer, respectively. The laser control signal is input to the PWM circuit via line 232 to determine the masking range in the main scanning and sub scanning directions of the printer.

A clock / timing pulse generation circuit 60 generates various timing pulses and clock (φ) synchronized with the crystal oscillator 64. φ is a symbol representing various pulses and includes a video clock VCLK and a clock 2VCLK having a half cycle of the video clock.

Next, the CCD 6 analog color processing & A / D circuit 75 will be described with reference to FIGS. 3 (A), 3 (B), 4 and 5.

As shown in FIG. 3A, the unit color separation line sensor (CCD) 6 is 62.5 μm (1/16 mm).
It is configured by arranging 5 chips in a zigzag pattern having 1024 pixels each having a corner area, and each pixel has a size of about 20.8 μm × 62.5 μm as shown in FIG. It is divided into three parts, and each of the three parts is B (blue),
G (green) and R (red) color separation filters are attached, and at the time of image reading, the document is scanned in the direction of the arrow in FIG. 3A, and the color separated image of the document 3 (see FIG. 1) is read.

FIG. 4 shows 8-bit digital data of each color separation image read by the above-mentioned 5-chip equal-size color separation line sensors (hereinafter referred to as color reading sensors) 101 to 105 arranged in a staggered pattern. An analog color processing & analog-to-digital conversion (A / D) circuit 75 that quantizes the data and outputs it to a color processing circuit (see FIG. 6) described later is shown.

FIG. 4 will be described with reference to the timing chart of FIG.

First, the color reading sensor 101 described above.
To 105, the analog pixel signals color-separated into the R, G, and B color components of the original 3 are amplified by amplifiers 106 to 11 in the first stage.
0, and logarithmic (log) conversion circuits 111 to 1
It is converted into the density value of the pixel by 15. At this time, each pixel signal has a pixel signal transfer clock (CLK) 201, as indicated by As202 in the timing chart of FIG.
In synchronism with the above, the color reading sensor outputs serially in the order of R1 → G1 → B1.

Next, a sample hold circuit (S / H)
116 to 120, the sampling signal S / shown in FIG.
The input image data is sampled and held at the timing of HP203, and then analog / digital (A / D)
A / D conversion is performed by the converters 121 to 125, and quantized into 8-bit (256-bit) 256-gradation image data.

In this way, the color-separated and quantized image data is processed by the DETA204 in the timing chart of FIG.
As shown in, the color separation data for the same pixel is serially transferred in a time-division manner.
In order to perform the color correction processing of 04 by a color correction circuit (see FIG. 6) described later, each of DR ₁ , DG ₁ and D of DETA 204 is
It is necessary to align B ₁ (here, R, G, and B respectively correspond to red, green, and blue. The same applies hereinafter) in advance to the same phase.

Therefore, LPR ₁ 205, LPG ₁ 206, and LPB ₁ 2 which are latch pulses having a phase difference with respect to time are provided.
07 according to DETA204 DR ₁ , DG ₁ , DB ₁ ...
· Sequentially latched in the latch circuits 126 to 130 to latch the output of the latch circuits 126-130 LP _R, L
P _G and LP _B are latched in the latch circuit 131 at the subsequent stage by the latch pulse (LCH) 208. As a result, the color separation data of the same pixel is finally latched in the same phase in the latch circuit 131.

Further, the color reading sensors 101 to 101 are provided.
Since 105 are arranged in a staggered manner as shown in FIG. 3A, in order to connect this sensor output to the output line of one line, buffer memories 132 to 134 buffer data for a plurality of lines. 1 for each color of R, G, B
The image data DR, DG, and DB that are continuous lines are output to the next stage.

For the same pixel obtained as described above, 8-bit color separation image data DR in phase with each other,
DG and DB are subjected to predetermined processing by the color processing circuit 76 shown in FIG. That is, the color correction circuit 135 shown in the figure performs the processing disclosed in the following item (1), which is usually called masking, and the corner (black) plate generation and undercolor removal circuit 136 discloses it in the item (2) below. Is performed. (1) Masking process ... In the color correction circuit 135, for the input pixel data DR, DG, DB 301 to 303,
The matrix operation represented by the following equation (1) is performed to absorb the unnecessary color component of the print toner.

[0040]

[Outer 1] Here, the coefficients ai, bi, and ci (i = 1 to 3) are masking coefficients that should be set to appropriate values. Also, Y ₁ ,
M ₁ and C ₁ are output signals 304 to 306 corresponding to the colors of yellow, magenta and cyan. (2) Corner plane generation and undercolor removal processing: In the corner plane generation and undercolor removal circuit 136, the signals Y, M, and C described above are used.
When the minimum value of MIN (Y, M, C) = k, Y ₂ =
_{Y 1 -αk, M 2 = M} 1 -βk, C 2 '= C 1 toner amount to reproduce indicia by calculation of _{-γk Y 2, M 2, C} 2 (307~3
09) is calculated, and a BK (black) signal BK = δk
(310) is used as a black plate for black printing. Here, the coefficients α, β, γ, and δ are set to appropriate values in advance.

At the same time, the signals of Y ₁ , M ₁ , and C ₁ are sent to the coefficient ROM via lines 311, 312, and 313, respectively.
Are inputted to the addresses of the respective lines, and the respective types are multiplied by the coefficients (a4, b4, c4) by the table conversion of the ROM, and the lines 314, 315, 316 to Y ₃ , M ₃ ,
It is output as C ₃ . Y ₃ , M ₃ , and C ₃ are added by adder 138 and output as ND signal to line 317.

Here, Y ₃ = a4 · Y ₁ , M ₃ = b4 · M ₁ , C ₃ = c4 · C ₁ , a
The relationship is 4 + b4 + c4≈1.

Therefore, the ND signal is an average of the image signals color-separated by the R, G, and B filters of the respective colors, and is considered to be similar to the density of the image signal in the entire visible region.

Next, each of the image data Y ₂ , M ₂ , C ₂ , and BK 307 to 310 obtained by the above circuit 136 becomes the basic data of the toner image finally printed by the printer 2. However, as will be described later, the color printer in this system uses a Y (yellow) toner image, M
The (magenta) toner image, the C (cyan) toner image, and the BK (black) toner image cannot be printed out on the transfer paper at the same time. Therefore, each toner image is sequentially transferred onto the transfer paper and the four colors are sequentially transferred. Since the printing method is such that a final color print image is obtained by superimposing them, each color data Y ', M', C ', BK and ND obtained by the above-mentioned circuit 136 is stored in the color printer 2
It is necessary to select it according to the operation of.

The selector 139 in the next stage is for this selection, and the color select signal S ₀ from the controller 74,
Depending on the combination of S ₁ and S ₂ , one image data is selected from the above-mentioned five types of image data Y ₂ , M ₂ , C ₂ , BK and ND and output to the printer. Therefore, the present system requires a document exposure operation for the number of toner colors used for reading out and printing out one color image document, and a toner image forming process.

Color signals Y, M, C and B selected here
It is possible to reproduce colors of K and ND in arbitrary colors, that is, color conversion. This can be achieved by varying the color select signal S _1, a developing color with respect to S ₂ selection signal S _'1, S' _2. S _'1, S' ₂ is yellow development in (0, 0), a magenta developing at (0,1), a cyan developing at (1,0), in such Figure 2 to select a black developing with (1,1) The developing device drive motor driver 85 is driven. Therefore ND
The signal can be reproduced not only in black but also in any of cyan, magenta and yellow.

The image signal selected as described above is output to the synchronous memory 77 via the line 319.

The synchronous memory 77 is a buffer memory for performing a scaling operation of the video signal in the main scanning direction and a position movement trimming, and the address signal A input from the scaling control circuit 81.
DR-W, ADR-R and R.V. ENABLE, P.I.
V. It is controlled by the ENABLE signal. 19 and 2
A description will be given using 0. The R / V. ENABLE
C from the section, that is, the end of the main scanning read image of the reader
NT1 2b images from (P point) until Q points after b ₁ from the end portion of the main scanning writing printer from CNT2 (P point)
_When moving to the Q'point after ₁ (various CNT1, CNT
2, b ₁ and 2b ₁ respectively represent the count number of VCLK. ), The copy interval signal of the simultaneous signal generation circuit 82 is set as follows.

SET2 = CNT1, SET3 = b ₁ , S
ET4 = CNT2, SET5 = 2b ₁ As a result, the left margin counters 45 of the reader and printer respectively
4, 456 or effective section counters 455, 457 are set, counting is performed after HSYNC, and R.
V. ENABLE, P.I. V. Generate ENABLE.

The main scanning effective section signal R. V. ENABLE and the main scanning effective section signal P. V. When the writing and reading operations to and from the synchronous memory 77 described above in ENABLE are performed, the position movement in the main scanning direction is achieved. That is, in FIG. 19, the main scanning effective section signal R. V. The image data for one line written in the synchronous memory 77 between the point P and the point Q of ENABLE is the main scanning effective section signal P. V. ENAB
It is read from the point P'to the point Q'of LE, and P → P '
And Q → Q ′ are moved in the main scanning direction.

FIG. 20 shows an example of the configuration of a scaling control circuit for scaling in the main scanning direction. Where 480 and 483 are
An address counter which gives an address to the synchronous memory 77, and counts a write address at 480, a read address at 483 as a pixel transfer clock VCLK, or a thinning clock Cka at this clock. Reference numeral 482 is a B / R / M (Binary rate multiplier) that generates this thinned clock Cka.
And the set signal SET8 as shown in FIG.
The input clock VCLK is thinned out at the ratio set by. For example, the set signal SET8 is 8 bits (2 ⁸ = 2
56), if the input frequency fin, the output frequency f
out is represented by the following equation.

Fout = M / 256fin (where M is a set value by SET8) That is, in the example of FIG. 21A, since M = 192 is set, it is thinned out to fout = 3/4 fin. ing.

The scaling is performed by inputting the thinned clock Cka and the input clock VCLK (Ckb) to the clock generation selector 407 of each of the address counters 405 and 406. When each of the clocks Cka and Ckb is selected in the combination shown in FIG. 21B, the desired scaling can be performed. Also, the value M of the set signal SET8
Needless to say, if is changed steplessly, stepless zooming is performed.

The video signal which has undergone the scaling and position movement processing in the synchronous memory circuit is sent to the PWM circuit 7 via the line 223.
8 is input. The PWM circuit 78 D / A converts the digital video signal and compares it with a triangular wave of a predetermined screen to perform pulse width modulation. Further, the screen line number switching signal SCRSEL input from the controller 74 switches the screen according to the image signal, and the tone switching signals K ₀ , K ₁ , K ₂ switch the tone of the image signal. Next, details of the PWM circuit 78 will be described.

FIG. 22 is a block diagram of the PWM circuit, and FIG.
Shows the timing diagram.

The input VIDEO DATA 700 is latched by the latch circuit 600 at the rising edge of VCLK 701 and synchronized with the clock. (See 700 and 701 in FIG. 23) VIDE output from the latch
O DATA 715 to LUT (look-up table)
The gradation is corrected at 601 and the D / A (digital / analog) converter 602 performs D / A conversion to generate one analog video signal, and the generated analog signal is the comparator 610 at the next stage. It is input to 610 and compared with a triangular wave described later. Signal 7 input to the other comparator
Reference numerals 08 and 709 are triangular waves (708 and 709 in FIG. 23) that are individually generated and synchronized with VCLK.

That is, a synchronizing clock 2VCLK 703 having a frequency twice that of VCLK 701 is divided into two by, for example, a JK flip-flop 606, and a triangular wave WV 1 generated by a triangular wave generating circuit 608 in accordance with a triangular wave generating reference signal 706. The other is 2VCLK divided by 6 circuit 60.
The triangular wave WV2 is generated by the triangular wave generation circuit 609 according to the signal 707 (see 707 in FIG. 23) generated by dividing the frequency by 5. Fig. 2 shows each triangle wave and VIDEO DATA
As shown by 3, all are generated in synchronization with VCLK. Furthermore, each signal is an HS that is generated in synchronization with VCLK.
Inverted HSYNC to synchronize with YNC702
Resets the circuits 605 and 606 at the timing of HSYNC.

With the above operation, CMP1 610, CM
Outputs 710 and 711 of P2 611 are input VID
A signal having a pulse width as shown in FIG. 24 is obtained according to the value of EO DATA 700. That is, in this system, as shown in FIG.
When the output of the AND gate 613 is "1", the laser is turned on to print dots on the print paper, and when the output is "0", the laser is turned off and nothing is printed on the print paper. Therefore, turning off can be controlled by the control signal LON (705).
FIG. 24 shows a state where the level of the image signal D changes from left to right from “black” to “white”. Since "white" is input as "FF" and "black" is input as "00" to the PWM circuit, the output of the D / A converter 602 is Di in FIG.
It changes like. On the other hand, the triangular wave is WV in (a)
In 1 and (b), it is the same as WV2, so CMP
The pulse widths of the outputs of 1 and CMP2 become narrower as they shift from "black" to "white" like PW1 and PW2.

Further, as is clear from the figure, when PW1 is selected, dots on the print paper are formed at intervals of P ₁ → P ₂ → P ₃ → P ₄ , and the pulse width change amount is within the dynamic range of W1. To have. On the other hand, if PW2 is selected, the dot becomes P
They are formed at intervals of ₅ → P ₆ , and the dynamic range of the pulse width is W2, which is three times that of PW1. By the way, for example, the print density (resolution) is about 40 at PW1.
0 line / inch, set to about 133 lines when PW2. Further, as is clear from this, when PW1 is selected, the resolution is improved by about 3 times as compared with when PW2 is selected, while PW
When W2 is selected, the dynamic range of the pulse width is about three times wider than that of PW1, so the gradation is remarkably improved.

Therefore, for example, when high resolution is required, P
When W1 requires high gradation, SCRSEL 704 is given from an external circuit so that PW2 is selected. That is, 612 in FIG. 22 is a selector and SCRSEL7
When 04 is "0", A input is selected, that is, when PW1 is "1", PW2 is output from the output terminal O, the laser is turned on by the finally obtained pulse width, and dots are printed.

The LUT 601 is a table conversion ROM for gradation correction, and has addresses 712 and 713 of K ₀ ,
Table switching signals K ₁ , K ₂ , 714 and video signal 715 are input, and VIDEO DA corrected from the output.
TA is obtained. For example SCRSE to select PW1
When L704 is set to "0", the outputs of the ternary counter 603 are all "0", and the correction table for PW1 in 601 is selected. Further, S ₀ and S ₁ are switched according to the color signal to be output. For example, K ₀ , K ₁ and K ₂ = “0, 0,
When it is "0", it is yellow output, when it is "0,1,0", it is magenta output, when it is "1,0,0", it is cyan output, and it is "1,1,0".
At the time of, it outputs black. This is due to the difference in gradation characteristics due to the difference in image reproduction characteristics depending on the color of the laser beam printer. Further, it is possible to perform gradation correction in a wider range by combining K ₂ , K ₀ and K ₁ . For example, the gradation conversion characteristics of each color can be switched according to the type of input image. Next, select SCRSE to select PW2.
When L is set to “1”, the ternary counter counts the line synchronization signal, and “1” → “2” → “3” → “1” →
“2” → “3” → ... Is output to the address 714 of the LUT. With this, the gradation correction table is switched for each line, whereby the gradation is further improved.

This will be described in detail with reference to FIG. A curve A in FIG. 7A is a characteristic curve of input data versus print density when PW1 is selected and the input data is changed from "FF" or "white" to "0" or "black". . As a standard, it is desirable that the characteristic is K. Therefore, B, which is the inverse characteristic of A, is set in the gradation correction table. FIG. 7B shows the gradation correction characteristics A, B, and C for each line when PW2 is selected, and the pulse width in the main scanning direction (laser scanning direction) is changed by the above-mentioned triangular wave and at the same time the sub scanning is performed. As shown in the figure, the direction (image feeding direction) is provided with three gradation levels to further improve the gradation characteristics. That is, the characteristic A becomes dominant in the portion where the density change is sharp, the sharp reproducibility is reproduced, the smooth gradation is reproduced by the characteristic C, and the gradation B is effective for the middle portion. Therefore, as described above, P
Even when W1 is selected, a high resolution is ensured and a certain degree of gradation is guaranteed, and when PW2 is selected, extremely excellent gradation is guaranteed.

Further, regarding the above-mentioned pulse width, for example, PW
In the case of 2, the pulse width W is ideally 0 ≦ W ≦ W2, but due to the electrophotographic characteristics of the laser beam printer and the response characteristics of the laser drive circuit, dots are printed with a pulse width shorter than a certain width. No (no response) area diagram 26
(A) 0 ≦ W ≦ wp, and there is a region in which the density is saturated, FIG. 26 (A) wq ≦ W ≦ W2. Therefore, the pulse width and the density are set so that the pulse width changes within the linear effective region wp ≦ W ≦ wq. That is, FIG. 26 (B)
As described above, when the input data changes from 0 (black) to FF _H (white), the pulse width changes from wp to wq, which further guarantees the linearity between the input data and the density.

The video signal converted into the pulse width as described above is supplied to the laser driver 11L via the line 224.
To modulate the laser light LB.

The laser beam LB modulated in accordance with the image data is horizontally scanned at a high speed by the polygon mirror 12 rotating at a high speed within the width of the arrow AB in FIG. 7, and the f / θ lens 13 and the mirror 14 are scanned. Then, an image is formed on the surface of the photosensitive drum 15, 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 the present embodiment, 1/16 mm in the feeding direction (sub-scanning direction).
It corresponds to the width of.

On the other hand, since the photosensitive drum 15 rotates at a constant speed in the direction of arrow L in the figure, the main scanning direction of the drum is
The laser beam is scanned as described above, and the photosensitive drum 15 is rotated at a constant speed in the sub-scanning direction of the drum, so that a planar image is sequentially exposed to form a latent image.
From the uniform charging by the charger 17 prior to this exposure → the above exposure → and the toner development by the developing sleeve 31, toner development is formed. For example, if the development is performed with the yellow toner of the developing sleeve 31Y corresponding to the first document exposure scanning in the color reader, a toner image corresponding to the yellow component of the document 3 is formed on the photosensitive drum 15.

Then, a yellow toner image is formed on the paper sheet 54 whose tip is carried by the gripper 51 and wound around the transfer drum 16 by the transfer charger 29 provided at the contact point between the photosensitive drum 15 and the transfer drum 16. Is transferred and formed. The same processing steps are repeated for M (magenta), C (cyan), and BK (black) images, and the toner images are superimposed on the paper sheet 54 to form a full-color image with four-color toner. It

Thereafter, the transfer paper 91 is separated from the transfer drum 16 by the movable separation claw 50 shown in FIG. 1, guided to the image fixing section 43 by the conveyor belt 42, and by the heat and pressure rollers 44 and 45 of the fixing section 43. The toner image on the transfer paper 91 is fused and fixed.

Next, a moving method in the sub-scanning direction will be described with reference to FIG.

FIG. 13 schematically shows a cross section in the sub-scanning direction (feeding direction). A is a home position at the time of standby, B and C are home positions at the time of reading by moving the reading area in the sub-scanning direction, respectively, and positions at the time of reciprocation of each scan.

FIGS. 14A, 14B, and 14C show the relationship of the positions recorded on the recording paper of the printer, which can be considered in association with FIG. FIG. 14 (A)
The shaded area on the circumference of the transfer drum 16 is the actuator plate 19 that generates a signal indicating the leading edge of the paper, and is a distance (l + l) from the point where the sensor S detects the leading edge of the recording paper.
When it is rotated by h), the toner image on the photosensitive drum is transferred to the recording paper. That is, during normal copying, when the reading unit of the reader is started from the home position A from the rising edge of the signal S, the signal when the leading edge of the document located at the distance T from that is read is exactly the PH of the photosensitive drum.
Modulates the laser light that hits a point. Therefore, at this time, the recording paper 9
As shown in FIG. 14B, the leading edge of the sheet 1 is on the front side by the distance h from the transfer point Tr, so the image of the leading edge T of the document is the recording paper 91
Will be formed at the tip of. Next, only the portion (a) of (x ₁ , y ₁ ) (x ₂ , y ₂ ) on the document table in FIG. 15 is read, and this is read (x ₃ , y ₃ ) (x ₄ , y The procedure in the sub-scanning direction when moving to position ₄ ) will be described.

Further, the reading home position of the reader section is set to the position B, that is, to l from the reading start position x _{1 in the} sub-scanning direction.
Just move to the front position, and the reading operation is performed based on the point B. That is, the distance between the reading start position and the home position at that time is always controlled to be l. On the other hand, assuming that the writing start position on the recording paper, that is, the position after movement, is a point of distance x ₃ from the front end of the paper, it is sufficient to delay from S from the printer by a distance n ₂ and start from the reading home position B. Recognize. That is, as a result, the image read from x ₁ on the platen is recorded on the recording paper from the position x ₃ (n _{2 in} FIG. 14C) from the leading edge of the paper, and moves in the sub-scanning direction. It has been done. In this embodiment, a stepping motor is used to drive the scanning of the reading unit, and the number of pulses used to drive the stepping motor corresponds to a moving distance of 1: 1. That is, since the distance can be defined by the number of pulses given to the driving regardless of the scanning speed, in other words, the scaling factor, all the distances described above are values converted into the pulses used for driving the stepping motor. Therefore, even if the scaling ratio changes and the scanning speed changes, the value to be set does not depend on it, and the control becomes simple.

In FIG. 8, for example, in the case of outputting a high gradation full color image in the designated area designated by the digitizer and a high resolution image (characters, line drawing, etc.) in the other areas in a single color (eg, black) C
The control flowchart of PU69 is shown.

FIG. 9A shows a region (coordinates (x ₁ , y ₁ ) (x ₂ , y ₂ )) designated by the digitizer. The specified area is output in full color, and the outside of the area is output in single color.

First, when it is detected in step S1 that the copy button is turned on, an area in the main scanning direction is set in steps S2 to S6. In S2, SET1 is set to Y ₀ , all valid image sections in the main scanning direction are designated, and SET1 is set.
Value is set in the counter 407 in FIG. S3,
S4 In the leader in the scanning direction trimming SET2 to define the area or masking (white) area (extraction of the image) and y _2, and the SET3 and y _1, and sets the respective counter 408, 409. This is a signal R. V. This is to form ENABLE.
Next, in S5 and S6, SET4 is set to y _{2 in order} to determine the trimming and masking area in the main scanning direction of the printer,
SET5 is set to y ₁ and set in the counters 410 and 411, respectively.

In the case of this example, since the reading position and the recording position are the same, the values of SET2 and SET4 and SET3 and SET5 are the same. When the actual image is read and formed, the R.S. V. ENABLE signal b,
P. V. The ENABLE signal d and the laser control signal e or e'are output. At the time of color recording of the designated area, the mode signals M ₀ , M ₁ , and M ₂ of FIG. V. The signal b as ENABLE is P.
V. The signal d and the laser control signal e ′ are selected as ENABLE, and the specified area is trimmed. On the other hand, when black recording is performed outside the specified area (M ₀ , M ₁ ,
M ₂ ) = (0, 0, 1) and R.M. V. ENA
BLE, P.I. V. V. with all sections on as ENABLE
ENABLEC is selected, the laser control signal e is selected, and the designated area is masked.

Returning to the flowchart of FIG. 8, step S
In S7 and S8, numerical values are set for controlling the image area in the sub-scanning direction.

Vreg1 and Vreg2 here are CP
It is the internal register counter of U69, and the drive pulse (2 in FIG. 2) of the stepping motor is input to this counter input.
36) has been input, therefore, when pulses are input by the number set in S7 and S8, an interrupt occurs internally and INT1 (S28 to S2) is applied to Vreg1 = 0.
9) and INT2 (S30, S for Vreg2 = 0)
31) is performed. Therefore, the point in the sub-scanning direction x ₂ (distance from home position to l + x ₁ ), the area from (l + n ₁ ) to x ₂ in FIG. 17B, that is, the distance (x ₁ + l + x ₂ ) is the image output section. At a point of Vreg1 = 0, that is, LOFF = 1 at INT1S28, the laser output is enabled. After that, the yellow output signals S ₀ , S ₁ , and S ₂ = 000, which are the first output colors, are output (S 9), and the above-described high gradation image quality selection signal SCRSEL = 1 is PWM.
It is sent to the circuit (S10), and the image effective section control signal (R.V.ENABLE, P.V.ENA) in the main scanning direction is sent.
M ₀ to set BLE, laser control signal)
Set M ₁ M ₂ = 110, and start the printer (S11).

In S13, a lamp lighting signal 241 for original exposure scanning is sent, the lamp 7 is turned on, and the paper leading edge signal S (FIG. 17B) from the printer is waited for. S14 '
Vreg3 is an internal counter that counts HSYNC and is set to 0 in S8 ', so that at the same time as S, the scan motor driven by the leader is advanced through S15. In point of x _1, x ₂ in advance, in order INT
1, INT2 is applied, and the laser lighting in the sub-scanning direction is controlled here. In S17, the motor moves backward, S18,
In S19, the vehicle stops at the home position. Here, since the same number of pulses as the stepping motor drive pulses required for the forward movement are applied to move backward, the home position sensor is not necessary.

After S20, the same steps are repeated with different colors, so that the area within the broken line in FIG.
Halftone images of C and BK (yellow, magenta, cyan, black) are formed (corresponding to the timing of the copy section in the designated area in FIG. 17B).

Next, in S23, S ₀ S ₁ S ₂ = 100, S ′ ₁
S ′ ₂ = 11 is selected and black reproduction of the ND signal is selected, the mode select signal M ₀ M ₁ M ₂ = 0.11 is set, and the laser control signal of FIG. V. ENABL
E, P. V. V. ENABLE. Select to output ENABLE (C), and in S24, select the image quality selection signal SCRS
Select EL = 0 and select a high-resolution image, and select Vreg1
Is set to 1 and Vreg2 is set to (1 + n ₃ ) to enable laser lighting over the entire area in the sub-scanning direction (S2
5, S26) and S14 to S19 are repeated to obtain FIG.
The area outside the broken line is printed out, and the area inside is not printed out.
As a result, a multicolor high-gradation image can be obtained in the designated region and a multicolor high-resolution image can be obtained outside the designated region. This is very effective for copying a document in which a halftone image and a character line drawing are mixed. Although the designated area is designated as a multi-color high gradation, the operation unit 6
7, it is possible to set the designated area to a high resolution of a single color and the outside of the area to a high tone of multiple colors. Further, it is of course possible to provide a plurality of designated areas and arbitrarily designate a multicolor high gradation and a single color high resolution for each designated area.

Next, another embodiment will be described. In this embodiment, two originals are placed on the original table as shown in FIG.
Area a of the first color document placed between points T and S
To move to the area b of the second original of the character or line drawing placed between the points S and U to reproduce multi-color high gradation, and reproduce high-resolution single color outside the area b of the second original. Is. When moving from the area a to the area b, zooming is required.

The control flow chart of this embodiment is shown in FIG.
To FIG. 12 and the timing chart is shown in FIG.

Description will be given along the timing chart. First, when the copy ON is detected in S40, the designated area is output in multi-color and high gradation. Therefore, in the same manner as the sequence described above with reference to FIGS. 8 and 9, the designated area of yellow, magenta, cyan, and black is selected. Output a multicolor high gradation image. Therefore S
It is the same as FIG. 8 and FIG. 9 except that the moved values from SET 42 to S48 are set as SET4 = y ₄ and SET 5 = y ₃ . S49, S49 in 'magnification ratio _{= | x 2 -x 1 / x} 4
Set -x ₃ | = α. Since the scaling ratio in the sub-scanning direction is realized by changing the speed of the stepping motor, in other words, the frequency of the drive pulse, the scaling ratio α is set by the scaling mode signal to the stepping motor driver 61 to drive. The speed of the driven motor changes. As described above, SET8 = α in S49 ′ is a scaling factor in the main scanning direction, and this causes scaling in the main scanning direction. In the case of this example, the magnification is set to be the same as that in the sub-scanning direction, but different values may be set.

Next, the home position is moved to point B (see FIG. 16). Since the output image is output from the position x ₃ from the leading edge of the recording paper, it is realized by delaying the scanning start of the reader by l + x ₃ from SP1 of the printer. This is done when Vreg3 = 0 in S58. This is indicated by the start of the scan. The first color, yellow, is selected in S52, SCRSEL = 1 is set in S53, and then the process is stopped in S63 (see FIG. 11).
Since steps S4, S65, and S66 are the same as those described with reference to FIGS.

After S67, there is shown a sequence in which the area other than the designated area b of the second original of the character line drawing placed between ΔS and ΔU in FIG. 15 is outputted as a monochromatic high resolution image. In S66 ', the home position is moved to the front .DELTA.C by the running distance l with respect to the original reading position .DELTA.S, and in S66 "the scaling factor is set to equal magnification, that is, .alpha. = 1 to set the scanning running distance l. Set to Vreg3 (S6
7), in S68, (M ₀ , M ₁ , M ₂ ) = (0, 0, 0) is set so that the laser beam can be turned on in the entire main scanning direction,
In S69, S ₀ , S ₁ , and S ₂ = to select the achromatic color density signal ND synthesized from the color-separated three color signals.
Output 100, Vreg1 = 1 Vreg2 = 1 + n
₃ is the laser lighting control in the sub-scanning direction as described above, (S7
0, S71), when the printer image signal SP1 is detected (S72), since Vreg3 = 0 immediately, the scan motor starts forward scanning. LOFF at the same time
= 1, the laser can be turned on (S76 (see FIG. 12)), and M ₀ M ₁ M ₂ = 001 at the position in the sub-scanning direction x _1.
As shown in FIG. 9B, the laser control signal is selected to whiten out the designated area (S7).
8). In this way, whitening is performed up to the position of x ₂ (S7
9), the whole area is output again in S80, and the forward scan is ended in S81. Thereafter, the same operation as S61 to S63 (see FIG. 11) is performed, and this sequence is completed.

With the above operation, the designated area of the first page can be scaled and moved to another designated area with multicolor high gradation, and the outside of the designated area can be combined and output with a single color high resolution. I understand.
In the above example, only one of the scaling and moving was performed, but both can be freely moved and scaled independently, and the order of colors and the selection of colors can be freely performed. It is possible to double. Also for gradation correction, by selecting K ₀ , K ₁ , and K ₂ , the designated area to be moved and other areas can be output with different gradation correction characteristics.

Further, by selecting S ₁ ′ and S ₂ ′ so as to change the development color with respect to the read color signal, it is possible to reproduce the designated area to be moved and other areas in different color conversion modes. Become.

Although two different originals have been described in this example, the same thing can be done when the area to be moved and the area to be moved are set for one original.

Further, although the color image forming apparatus using electrophotography has been described in this embodiment, various recording methods such as ink jet recording, thermal recording and thermal transfer recording are applicable not only to electrophotography. Is also possible.
Further, although an example in which the reading unit and the image forming unit are arranged close to each other as a copying apparatus has been described, the present invention can be applied to a form in which image information is transmitted by a communication line while being separated from each other.

[0091]

As described above, since the image processing apparatus of the present invention increases the recording resolution in the single color copying mode as compared with that in the plural color copying mode, it is possible to clearly reproduce characters, line drawings and the like. Become. In addition, since the reproduction gradation is improved in the multi-color copying mode as compared with the single-color copying mode, it is possible to improve the reproduction of the halftones required in the color copying. In these cases, the user makes troublesome designation. Extremely high usability without the need.

[Brief description of drawings]

FIG. 1 is an internal configuration diagram showing an example of a digital color copying apparatus to which the present invention is applied.

FIG. 2 is a block diagram of an electric circuit of the digital color copying machine shown in FIG.

FIG. 3 is a diagram illustrating a unity color separation line sensor in the document scanning unit of FIG.

FIG. 4 is a configuration diagram of a color reading circuit.

5 is a timing chart showing signal waveforms of the circuit of FIG.

FIG. 6 is a block diagram showing a configuration example of a circuit that performs color processing of a color image signal, generation of an ND image signal, and selection of a color image signal.

7 is a perspective view showing in detail a main part of the printer portion of FIG.

FIG. 8 is a flowchart of CPU control in the case of outputting a high gradation full color image in a designated area in the same original document and a high resolution image in a single color in the other areas.

9A is an explanatory diagram of coordinates of a designated area in the mode of FIG. 8, and FIG. 9B is a timing chart diagram of an image control signal in the mode.

FIG. 10 is a diagram showing a part of a flow chart of CPU control in a mode in which two originals are used to perform trimming synthesis at an arbitrary position by mixing a single color and a full color.

FIG. 11 is a diagram showing a part of a flowchart of CPU control in a mode in which two sheets of original are used to perform trimming synthesis at an arbitrary position by mixing single color and full color.

FIG. 12 is a diagram showing a part of a flowchart of CPU control in a mode in which two sheets of original are used to perform trimming composition at an arbitrary position by mixing single color and full color.

13 is an explanatory diagram of a document table in the reader unit of FIG. 1, a home position of the scanner, and a scanning distance of the scanner.

14 is a diagram showing the relative relationship between the transfer drum in the printer unit of FIG. 1 and the scanner position in FIG.

15 is an explanatory diagram of designated coordinates in the modes of FIGS.

16 is a sequence timing chart diagram of scanner driving and drum driving in the modes of FIGS.

17A is a timing chart diagram for generating an image synchronization signal from a video detection signal, and FIG. 17B is a sequence timing chart diagram for scanner drive and drum drive in the mode of FIG.

FIG. 18: Reader (original), printer (copy image)
FIG. 3 is a circuit diagram of a synchronization signal generation circuit that generates an effective section signal of the image signal in the main scanning direction and a laser control signal.

FIG. 19 is a timing chart of signals for position movement and magnification change in the main scanning direction.

FIG. 20 is a block diagram of a scaling control circuit in the main scanning direction.

21A is a signal waveform diagram showing an example of the signal waveform of FIG. 20, and FIG. 21B is an explanatory diagram showing the contents of the selector signal of FIG.

FIG. 22 is a circuit diagram of pulse width modulation of an image signal (laser).

23 is a timing chart of the circuit operation of FIG. 22.

FIG. 24 is a diagram showing pulse width modulation of an image signal (laser) and gradation correction characteristics on a gradation screen.

FIG. 25 is a diagram showing gradation correction characteristics for different gradation screens.

FIG. 26 is a diagram showing the relationship between the effective pulse width of the laser and the gradation.

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[Procedure amendment]

[Submission date] May 27, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be amended] Claims

[Correction method] Change

[Correction content]

[Claims]

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0006

[Correction method] Change

[Correction content]

[0006]

An image processing apparatus according to the present invention comprises an input means for inputting a digital image signal for each pixel, and a first pattern signal for the digital image signal for each pixel input from the input means. First pulse width modulation signal generating means for generating a first pulse width modulation signal in comparison with
Second pulse width modulation signal generation means for comparing the digital image signal for each pixel input from the input means with a second pattern signal to generate a second pulse width modulation signal; and the first pulse width The first pattern signal is a pattern signal having an extremum approximately at the center of one cycle with m pixels as one cycle, and a selection means for selecting the modulation signal and the second pulse width modulation signal. The second pattern signal is a pattern signal having n (n ≠ m) pixels as one cycle and having an extreme value at approximately the center of the one cycle.

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0091

[Correction method] Change

[Correction content]

[0091]

As described above, according to the image processing apparatus of the present invention, since the pulse width modulation signals generated by the pattern signals having different periods are generated in parallel, the switching can be performed at an acute angle, and the In addition, a pulse width modulation signal based on an optimum pattern signal can be selected in real time according to image data, and deterioration of image quality can be reduced in high-definition image recording. In addition, since the pattern signal has a pole at the center of one cycle, the pulse width does not grow from the beginning of one cycle, but the pulse width grows from about the center of one cycle.
Therefore, the spatial frequency of the formed image becomes constant, and beats such as the moire phenomenon can be reduced. Further, when one period of the pattern signal is set to an interval over a plurality of pixels, the end of the pulse width modulation signal of the preceding recording side pixel in a pair of adjacent pixels coincides with the end of the pixel, and the pulse of the succeeding recording side pixel The start end of the width modulation signal coincides with the start end of the pixel, the pulse width modulation signal is continuously generated between the pair of pixels, and the density unstable region caused by the intermittent pulse width modulation signal is reduced to reduce the image quality. It is possible to obtain the effect of reducing the decrease.

Claims (1)

[Claims] 1. An image processing apparatus having a multi-color copying mode and a mono-color copying mode, and a designating means for designating the multi-color copying mode and the mono-color copying mode, and comparing the recording resolution in the mono-color copying mode with that in the multi-color copying mode. An image processing apparatus, comprising: a resolution switching unit for enhancing the image processing apparatus.