JPH05316317A - Image forming device - Google Patents

Abstract

PURPOSE:To obtain a negative picture and a positive picture with picture quality close to an original by setting a thickening or a thinning amount applied to a picture signal based on a picture output mode through adjustment and exposing a photosensing body based on a processed picture recording signal. CONSTITUTION:R and C signals are inputted to a shading circuit 120, in which dispersion is corrected and the result is inputted to a lookup table(LUT) 140 and inverting circuits 130R, 130C. The LUT 140 receives digital information 300R, 300C and outputs color discrimination signals 310A-310C. FIFO memories 510R, 510C output 8-bit digital information signals 300R, 300C to the LUT 140, and the inverting circuits 130R, 130C and a timing control circuit 520 outputs its output to an R/C separator circuit 500, the FIFO memories 510R, 510C. Moreover, a thickening/thinning circuit 270 sets the thickening/thinning amount to a picture signal and a static latent image is formed on a photosensing body by the signal subjected to the thickening/thinning processing.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus for scanning and exposing a light beam on the basis of digitally processed image information to develop an electrostatic latent image formed on a photoconductor to obtain a visible image. Is.

[0002]

2. Description of the Related Art Conventionally, an image forming apparatus of this type has a structure in which a light beam is scanned and exposed based on digitally processed image information to develop an electrostatic latent image formed on a photoconductor to obtain a visible image. In that case, different exposure methods are adopted.

That is, a background scan method for exposing a non-image portion and an image scan method for exposing an image portion are adopted.

In such an image forming apparatus, when converting a negative image into a positive image, or conversely, when outputting a positive image into a negative image in reverse, both of them perform negative / positive conversion of each image signal. This is performed by signal processing that inverts the output bit.

[0005]

However, in the background scan type image forming apparatus, as shown in FIG.
As shown in FIG. 9, the laser spot diameter of the laser beam printer is set to be larger than the pixel size in order to stabilize a wide white area, and the laser spot overlaps the black area. As described above, there is a problem in that the image portion is reproduced thinner than the actual image and the non-image portion is reproduced thicker.

Similarly, in an image scanning type image forming apparatus, the laser spot diameter of a laser beam printer is set to be larger than the pixel size in order to stabilize a wide black area, and the laser spot overlaps a white area. Because of this, there is a problem that the image portion is reproduced thicker and the non-image portion is reproduced thinner than the actual image.

The present invention has been made to solve the above-mentioned problems, and by adjusting the amount of fatness or the amount of thinning of an image-processed image recording signal, a negative image can be obtained regardless of the exposure method. Another object is to obtain an image forming apparatus capable of outputting a positive image with an image quality close to that of an original document or an ideal image.

[0008]

An image forming apparatus according to the present invention is directed to an image processing means for performing a predetermined image signal processing on an input image signal and an image recording signal output from the image processing means. A mode selecting means for selecting an image output mode; a setting means for automatically setting a thickening amount or a thinning amount for the image signal by the image processing means based on the image output mode selected by the mode selecting means; And an exposing unit that forms an electrostatic latent image by exposing the photoconductor to a light beam based on an image recording signal that is thickened or thinned and output from the processing unit.

Further, the setting means is configured to selectively set either the negative image output mode or the positive image output mode as the image output mode.

Further, the image processing means is constituted so as to automatically select the thickening processing or the thinning processing according to the negative image information or the positive image information based on the image exposure method for the photoconductor by the exposing means. It is a thing.

[0011]

In the present invention, when the image output mode is selected by the mode selection means, the setting means determines the amount of thickening or thinning performed on the image signal by the image processing means based on the selected image output mode. A negative image and a positive image are formed by exposing the photosensitive member with a light beam to form an electrostatic latent image on the basis of an image recording signal that has been adjusted, adjusted, and thickened or thinned. It is possible to obtain the image quality close to that of the original.

Further, the setting means selects and sets either the negative image output mode or the positive image output mode as the image output mode so that the image processing means outputs an image signal in the negative image output mode or the positive image output mode. On the other hand, the exposure means exposes the light beam to the photoconductor to form an electrostatic latent image based on the image recording signal which has been subjected to the optimal thickening process or thinning process corresponding to each mode.
It is possible to generate an image recording signal that optimally reproduces a negative image and a positive image.

Further, the image processing means automatically selects the thickening processing or the thinning processing according to the negative image information or the positive image information based on the image exposure method for the photoconductor by the exposing means, and The exposure means exposes the photoconductor to a light beam on the basis of the image recording signal obtained by performing the optimum thickening or thinning processing on the image signal by the image processing means without depending on the exposure method. By forming a latent image, it is possible to generate an image recording signal that is independent of the exposure method.

[0014]

FIG. 1 is a sectional view showing an example of an image forming apparatus showing an embodiment of the present invention, in which a main body 1 includes a document scanning section 2, a sheet feeding section 3, an image recording section 4, and an intermediate tray section 5. Etc.

First, the structure of the document scanning section 2 will be described.

The controller section 2a is composed of means for controlling the copy sequence as a whole and image processing means for processing the image signal read by the CCD line sensor 20c. Reference numeral 2b is a power switch, and 2c is an original exposure lamp, which constitutes an optical scanning system together with a scanning mirror, and scans and moves at a predetermined speed. The light passing through the half mirror 20a is
After passing through the CCD imaging lens (lens) 20b, it is photoelectrically converted by the CCD line sensor 20c and sent to the image processing means of the controller section 2a as an image electric signal.

The reflected light from the half mirror 20a is sent to the imaging lens 2d after passing through a red elimination filter (red filter) 20d or a blue elimination filter (blue filter) 20e or a route using neither a filter nor a shutter. .. The imaging lens 2d forms an image of the reflected light of the half mirror 20a on the photosensitive drum 11 of the image recording unit 4. That is, in this embodiment, analog image recording is performed.

The buzzer 2e warns of a copy mode error or the like set by the operation section described later. The optical system drive motor 2f drives the optical scanning system and the like with high accuracy. Next, the paper feeding unit 3 feeds the cut sheet SH into the image recording unit 4 by driving the paper feeding rollers 3a and 3b.

Next, the structure of the image recording section 4 will be described.

The registration rollers 12 are the paper feed rollers 3a,
The cut sheet SH fed by the driving of 3b is once stopped, and after synchronizing the leading edge of the image, the cut sheet SH is fed again.

The developing units 13a and 13b contain color-specific developers (red and black), and the solenoid 14
By selectively driving a and 14b, the developing unit 13a,
Either one of 13b is arranged close to the photosensitive drum 11, and the other is retracted from the photosensitive drum 11.

When performing multiple development, the controller section 2a controls the driving of the solenoids 14a and 14b. The transfer charger 15 transfers the toner image developed by the developing units 13a and 13b onto the cut sheet SH, and the post-transfer separation charger 16 separates the cut sheet SH from the photosensitive drum 11. The pre-exposure lamp 17 neutralizes the surface potential of the photosensitive drum 11 and prepares for primary charging. The cleaner device 18 includes a cleaning blade and a cleaning roller, and collects the toner remaining on the photosensitive drum 11. The fixing device 19 is a cut sheet SH.
The toner image transferred to is fixed by heat and pressure. The transport roller 20 transports the cut sheet SH for which the fixing process has been completed to the paper discharge tray 24.

Next, in the case of multiple copy, the flapper 21 is switched to the position shown by the dotted line by the operation of a solenoid (not shown), and the cut sheet SH that has been fed, transferred, separated, and fixed has a conveyance path. After passing through 22, the sheet is sequentially conveyed in the conveying direction 22a, the paper is detected by the sensor S5, then detected by the sensors S6 and S8, and the lateral registration is performed by the solenoid for lateral registration. Then, the registration roller 12 is driven by a multiple copy command from the operation unit 41 (see FIG. 2), and the cut sheet SH is sent to the position of the registration roller 12. After that, the sheet is discharged to the sheet discharge tray 24 in the same manner as the above-described operation.

Further, during double-sided copying, the transfer sheet is ejected by the sheet ejection roller 23 as in the case of the above-described normal image forming operation, but after the trailing edge of the cut sheet SH has passed the flapper 21. The discharge roller 23 is driven in the reverse direction, and the cut sheet SH is guided by the flapper 21 and introduced into the transport path 22. This reverse drive is
It is performed by a solenoid that controls forward and reverse rotation. Subsequent operations are the same as in the case of the multiple copy described above. As described above, in the case of double-sided image formation, the cut sheet SH is once ejected from the discharge roller 23 to the outside of the machine, and the cut sheet SH is turned upside down by the reverse rotation drive of the discharge roller 23 and fed in the transport direction 22a. It MM is a main drive motor.

Next, the registration roller 12 is driven by a multiple copy command from the operation unit 41, and the cut sheet SH is fed to the position of the registration roller 12. After that, the sheet is discharged to the sheet discharge tray 24 in the same manner as the above-described operation. Further, in the case of multiple copies of a plurality of sheets, the intermediate tray section 5 is used. As shown in FIG. 1, the intermediate tray portion 5 includes
An intermediate tray 30 for temporarily storing the cut sheets SH on the transport path 31 is provided. In the case of multiple copies of a plurality of sheets, the fixed cut sheet SH is
After the paper is partially ejected by the paper ejection roller 23 under the same control as in the double-sided copying of the sheet copy, the paper ejection roller 23 is driven in reverse to drive the intermediate tray via the conveyance path 22, flapper 32, and conveyance path 36. It is stored in 30. This operation is repeated, and after the first side is completely accommodated in the intermediate tray 30, the second side receives the feeding roller 33 by the next copy command.
Is driven, and the second side copy is executed via the transport path 36. Incidentally, 34 is a conveying roller, and 35 is a feeding roller.

On the other hand, in the case of a plurality of double-sided copies, the flapper 21 passes through the conveyance paths 22 and 36 from the fixing device 19 and stores them in the intermediate tray 30 under the same control as in the above-mentioned one-sheet multiple copy. Subsequent operations are the same as those in the case of the multiple copy described above, and the description thereof will be omitted here.

Next, the scanner motor 25 rotates the rotary polygon mirror 25a at a predetermined speed to deflect the laser beam emitted from the semiconductor laser 26. It should be noted that the scanner motor 25, the semiconductor laser 26 and the like constitute a digital scanning unit, which emits a laser beam corresponding to the digital image information input from the image processing means of the controller 2a and obtains it by the above-mentioned analog image recording. The recorded image is recorded as a superimposed image of this digital image recording, and at the time of analog image recording, the latent image region recorded on the photosensitive drum 11 is irradiated with a laser beam to selectively erase the latent image. It also operates. The exposure shutter (shutter) 27 blocks part or all of the reflected image light and suppresses the latent image area. Further, 28 is a primary charger, and 999 is a document.

Further, S1 to S15 and S19 to S2 in the figure
Reference numeral 3 denotes a sensor, and the sensor S1 detects the home position of the optical system serving as the analog scanning unit.

FIG. 2 shows the controller section 2a shown in FIG.
2 is a block diagram for explaining the configuration of FIG. 1, and the same components as those in FIG.

In the figure, reference numeral 41 denotes an operation section, which is a key for setting a copy mode (single-sided, double-sided, multiplex, etc.) and an image forming mode (magnification, paper size, etc.), and is further fed from an automatic document feeder (ADF). A first mode setting key for setting a first recording mode in which digital information stored in advance from the digital scanning unit is superimposed on all originals to be printed, and to a specific original fed from the automatic document feeder. On the other hand, a second mode setting key for setting a second recording mode for superimposing digital information stored in advance from the digital scanning unit is arranged (not shown). 42 is a control unit (controller), and CP
The U42a, the ROM 42b, the RAM 42c, etc., and collectively controls the image forming sequence based on a control program stored in the ROM 42b. An editor 43 inputs an area designation for a predetermined area of the original. A shutter portion 44 is composed of an exposure shutter 27 and a solenoid. Reference numeral 45 denotes a laser section, which is a semiconductor laser 2
6. The scanner motor 25 and the like. 46 is AC
The driver applies A to the AC load 47 such as the original exposure lamp 2c.
Supply C power. A motor control unit 48 and a DC load control unit 49 control the driving of the solenoids 14a and 14b, the clutch, the fan, and the like. A feeder control unit 50a controls the driving of the document feeding unit. 50b is a sorter,
Cut sheet S discharged by driving the discharge roller 23
Output H to the specified output bin. The HVT is a high-voltage unit that applies a voltage of a predetermined potential to the charging system and the developing sleeves of the developing units 13a and 13b. DCP
Is a DC power supply, and supplies a control potential “+ 5V” to the controller unit 2a and the like.

The latent image forming process of a black image on the photosensitive drum 11 will be described below with reference to FIGS.

FIG. 3 is a plan view showing the latent image forming optical path of the photosensitive drum 11 shown in FIG. [Black image latent image forming process] First, as a pre-operation for performing a latent image of a black image, the red filter 20d is set in front of the imaging lens 2d. The original 999 including red information is illuminated by the original exposure lamp 2c and the scanning mirror. The original exposure lamp 2c and the scanning mirror are an optical system drive motor (optical motor).
From 2f, it moves in the direction of arrow b in FIG. Manuscript 999
The reflected light from is reflected by the half mirror 20a,
It is input to the red filter 20d. Red filter 20d
Erases the red color information in the original 999. The reflected light from the original 999 from which the red information has been erased is reflected by the imaging lens 2d.
And the image is formed on the photosensitive drum 11. As described above, the latent image based on the information other than the red information of the original 999 is formed on the photosensitive drum 11. Hereinafter, the latent image forming process of the red image on the photosensitive drum 11 will be described with reference to FIGS. 1 and 4. [Red image latent image forming process] The shutter 27 is closed as a pre-operation for forming a red image latent image. By closing the shutter 27, the optical information from the imaging lens 2d is blocked.
The original 999 is illuminated by the original exposure lamp 2c and the scanning mirror. The document exposure lamp 2c and the scanning mirror are driven by an optical system drive motor (optical motor) 2f, and the arrow b shown in FIG.
Move in the direction. The reflected light from the original 999 passes through the half mirror 20a and forms an image on the CCD line sensor 20c by the lens 20b.

FIG. 4 is a circuit block diagram for explaining the structure of the CCD line sensor 20c shown in FIG.

There are two line sensors, a line sensor P1 in which a red optical filter is fitted and a line sensor P2 in which a cyan optical filter is fitted, and the charges accumulated in these line sensors for a predetermined time are , All the pixels are collectively transferred to the shift registers P3 and P4. The R signal is shifted in the shift register P3 by the shift clock CLK and output. Further, since the C signal is read earlier by one line than the R signal, the amount of advance is absorbed by the line buffer P5 for one line and is output in phase with the R signal. CC
The R signal and the C signal from the D line sensor 20C are input to the controller unit 2a as analog signals.

FIG. 5 shows the controller section 2a shown in FIG.
It is a block diagram explaining the structure of the image processing part in the inside. The configuration and operation will be described below.

The R and C signals from the CCD line sensor 20c are input to the amplifier 100.

The amplifier 100 outputs the output of the amplifier 100 to the next stage of the A / D converter 1 when the CCD line sensor 20c reads the white plate installed in the document scanning section 2.
The R signal and the C signal are amplified so as to have a full scale of 10. The output signal from the amplifier 100 is subjected to analog / digital conversion in the next A / D converter 110, and becomes 8-bit digital information. A / D converter 1
The output of 10 is input to the shading circuit 120. Here, variations in the sensitivity of the CCD line sensor 20c, unevenness in the light amount of the document exposure lamp 2c, and the like are corrected. The shading circuit 120 has a lookup table (L
UT) 140 and the inverting circuits 130R and 130C. The LUT 140 is a red-based digital information 300R.
And the color discrimination signal 3 from the blue digital information 300C.
It outputs 10A to 310C. 510R and 510C are F
In the IFO memory, 8-bit digital information 300R,
The digital information 300C is transferred to the LUT 140 and the inverting circuit 13
Input to 0R and 130C. 520 is a timing control circuit, which includes the R / C separation circuit 500 and the FIFO memory 51.
A timing signal is output to 0R and 510C.

In the image forming apparatus thus constructed, when the image output mode is selected by the mode selecting means (including the operation section 41 etc.), the setting means (CPU 42a).
Based on the selected image output mode, the image processing means (including the thickening / thinning circuit 270) adjusts and sets the thickening amount or the thinning amount to be performed on the image signal, and the thickening process or the thinning process is performed. The exposure means exposes the photosensitive member with a light beam to form an electrostatic latent image on the basis of the image-recorded signal subjected to the processing, thereby making it possible to obtain a negative image and a positive image with an image quality close to the original. ..

Further, the setting means selectively sets either the negative image output mode or the positive image output mode as the image output mode so that the image processing means outputs an image signal in the negative image output mode or the positive image output mode. On the other hand, the exposure means exposes the light beam to the photoconductor to form an electrostatic latent image based on the image recording signal which has been subjected to the optimal thickening process or thinning process corresponding to each mode.
It is possible to generate an image recording signal that optimally reproduces a negative image and a positive image.

Further, the image processing means automatically selects the thickening processing or the thinning processing according to the negative image information or the positive image information on the basis of the image exposure method for the photoconductor by the exposing means, and The exposure means exposes the photoconductor to a light beam on the basis of the image recording signal obtained by performing the optimum thickening or thinning processing on the image signal by the image processing means without depending on the exposure method. By forming a latent image, it is possible to generate an image recording signal that is independent of the exposure method.

The color discrimination processing operation will be described below with reference to FIGS.

FIGS. 6 and 7 are schematic diagrams showing the table structure of the color judgment table in the image forming apparatus according to the present invention. FIG. 6 judges the color judgment signal 310A for red and the color judgment signal 310C for black. 7 corresponds to the color determination table for determining the color determination signal 310B for blue and the color determination signal 310C for black.

For example, red-based digital information 300R
Is "200", and the blue digital information 300C is "1".
In the case of "00", since this value is in the red region from FIG. 6, the red discrimination signal 310A becomes "1". In FIG. 7, since the area is other than the blue area, the blue determination signal 310B
Becomes "0". The black determination signal 310C is input to the contact extraction circuit 230. The selector 160 is the CPU 4
The control line is controlled by an I / O port (not shown) of 2a, and the control line is set to "0" when the red color separation is performed, and the control line is set to "1" when the blue color separation is performed.
Hereinafter, a case where the control line is "0", that is, a case where red-based color separation is performed will be described. The output signal (red area signal) 330 of the selector 160 is the red determination signal 3
10A is selected, the contact extraction circuit 230 and A
It is connected to the ND circuit 210.

FIG. 8 shows a contact extraction circuit 230 shown in FIG.
FIG. 6 is a schematic diagram illustrating the operation of FIG.

The contact extraction circuit 230 is composed of, for example, a 3 × 3 matrix, and when both red and black information are included in the four pixels of the target pixel, as shown in FIG. The information is “1”. If neither the red information nor the black information is included in the four pixels around the target pixel, the contact information is set to “0” as shown in FIG. 8B. FIG. 8C shows contact information 400 when red and black images intersect. Hereinafter, the operation of the expansion circuit 240 shown in FIG. 5 will be described with reference to FIG.

FIG. 9 is a diagram for explaining the operation of the expansion circuit 240 shown in FIG. 5. FIG. 9A shows a basic matrix configuration for expansion, and the basic matrix is, for example, 9
When the contact information 400 is formed in a size of × 9 and the target pixel is excluded, the contact information 400 is set in the matrix excluding the target pixel as “1”.
If there is not, the pixel of interest is set to “0”. 9B shows a state in which the two pieces of contact information A and B are expanded using the matrix of FIG. 9A, which is indicated by a chain line in the figure. Expansion information B indicates a state expanded from the contact information B, and is indicated by a two-dot chain line in the figure.

The expansion information A and B are input to the compression circuit 250 through the signal line 410. The compression circuit 250 is also formed of a 9 × 9 matrix similarly to the expansion circuit 240, and when all the matrix except the pixel of interest is expansion information, the pixel of interest is set to “1” as shown in FIG. Others are set to "0". The synthesis circuit 2 uses this set of “1” information as compression information through the signal line 420.
Enter in 60. The red-based digital information (luminance signal) 300R, which is the output from the shading circuit 120, and the blue-based digital information 300C, which is the output from the shading circuit 120, are respectively inverted by the inversion circuits 130R and 130R.
130C inverts and inverts signals 320B and 320A
Becomes The inverted signal 320B is a red-based luminance signal 300R.
Since it is an inverted signal, it becomes a cyan-based density signal. The inverted signal 320C is the blue-based luminance signal 30.
Since it is a signal obtained by inverting 0C, it becomes a red-based density signal.

In the selector 150, the port B, that is, the red system is selected by the control line, and the output signal of the selector 150 is the digital information (luminance signal) 3
00R is selected. In the next selector 170, a negative / positive image can be selected. Red-based density signal 340
Is input to the port (terminal) X of the selector 170, and Y
A fixed value (“32” in this embodiment) is input to the terminal.

Further, the S terminal of the selector 170 has A
The output signal 380 from the ND circuit 210 is connected. The red area signal 330 and the contact signal 390 obtained by inverting the contact signal 400 by the inverting circuit 220 are input to the AND circuit 210.

FIG. 11 shows an AND circuit 210 shown in FIG.
FIG. 3 is a schematic diagram showing the input / output relationship of FIG. As shown in this figure, a case where there is a red round image in the black image is shown, and the red area signal 330 indicating the red area and the contact information 400 indicating the portion where the red image and the black image are in contact are shown. A control signal 380 obtained by subtracting the contact information 400 from the red area signal 330 is input to the S terminal of the selector 170.

FIG. 12 is a timing chart showing the signal selection processing operation of the selector 170 shown in FIG.
The case where the red-based density signal 340 is selected is shown.

As shown in this figure, the red region signal 3
If the red-based density signal 340 is simply selected by 30, black information is mixed in a desired red region at a point where the resolution of OCD changes from black to red. Therefore, in this embodiment, the control signal 36 of the selector 170 is passed through the selector 171 using the contact signal 400 that changes from black to red and from red to black.
Create 0. In this way, the signal 350 only in the desired red region can be extracted.

FIG. 13 is a diagram showing the density signal extraction processing by the selector 170 shown in FIG.

As shown in this figure, when the red-based density signal 350 is extracted from the red-based density signal 340 based on the control signal 380 input to the S terminal of the selector 170, the red-based density signal 350 is extracted. The signal 350 is input to the edge enhancement circuit 180 and the averaging circuit 190 in the subsequent stages, respectively.

The edge emphasizing circuit 180 emphasizes the edge portion of the red-based density signal 350 which is an input signal. Further, the averaging circuit 190 averages the red-based density signal 350 serving as an input signal in a 9 × 9 matrix. The output signals 360E and 360S, which are the respective outputs of the edge emphasizing circuit 180 and the averaging circuit 190, are input to the binarizing circuit 200 of the next stage. The binarization circuit 200 compares the 8-bit output signal 360E of the edge enhancement circuit 180 with the 8-bit output signal 360S and outputs a 1-bit red signal 370 to the synthesis circuit 260 in the subsequent stage. The operation of the combining circuit 260 shown in FIG. 5 will be described below with reference to FIG.

FIGS. 14A and 14B are schematic diagrams for explaining the synthesizing operation of the synthesizing circuit 260 shown in FIG. 5, where FIG. 14A shows a state in which red and black images intersect with each other, and FIG. Shows a state in which the red image is separated, which corresponds exactly to the red signal 370. (C) is the compression circuit 25 shown in FIG.
0 shows the content of the output signal 420, and (d) shows the red signal 3
70 and output signal 420 combined signal 43
Corresponds to 0.

As described above, by combining the red signal 370 with the output signal 420 serving as the compression information signal, the missing of the red information due to the intersection of the black and red images can be interpolated. Combined signal 430 of combining circuit 260
Is input to the thickening / thinning circuit (thick / thin circuit) 270 in the next stage. The operation of the thickening / thinning circuit (thick / thin circuit) 270 will be described below with reference to FIGS.

15 and 16 are schematic diagrams for explaining the operation of the thickening / thinning circuit (thick / thin circuit) 270.
The image forming apparatus according to the present embodiment finally forms an image by exposing a portion other than red information with a laser beam emitted from a semiconductor laser (by a background scan method). At this time, the spot diameter of the laser beam is larger than the pixel size as shown in FIG. This is because some overlap is required to secure a white level by the laser beam. Therefore, as shown in FIG. 20, when a line image of 1 pixel width is formed, the red line becomes thin. The white line or the thickening of the line image of the negative image is corrected as shown in FIG.

That is, when outputting a positive image, the thick / thin circuit 270 thickens the binarized image NORI in the main scanning and sub-scanning directions to obtain a thick image FATI. By executing such processing in advance, it is possible to cancel the thinning of the red line and the thickening of the white line due to the background scan.

On the other hand, when outputting a negative image, the thick / thin circuit 270 thins the binarized image NORI in the main scanning and sub-scanning directions to obtain a thin image THII. .. By performing such a process in advance, the image part is thickened by the image scan,
It is possible to cancel the thinning of the non-image portion.

FIG. 17 shows the thick / thin circuit 270 shown in FIG.
3 is a circuit block diagram illustrating a detailed configuration of FIG.

In the figure, reference numeral 901 denotes a binarized image signal input portion, and when a positive image is output, an image signal of "H" level is input to the image portion and an image signal of "L" level is input to the non-image portion. on the other hand,
When outputting a negative image, the image part is "L" and the non-image part is "H".
The image signal of the level is input. Further, both the binarized image signals are "L", the laser is turned on, and a white portion is formed. In the binarized image signal input from the input unit 901, an image signal 903 delayed by one line by the line memory 902 is an image transfer clock (CLK1).
Latch / shift processing is executed by the flip-flops 906a to 906c by the clock (CLK2) 905 having a half cycle of 904, and the four data in the main scanning direction subjected to the latch / shift processing are thinned by the OR gate in the subsequent stage. It is processed and input to the selector 907. Reference numeral 912 is a 5-bit select signal transmitted from the CPU 42a, and a 3-bit select signal 912 of 0 to 2 bits is input to the S terminal of the selector 907. Selector 907
Can be thickened / thinned by a 3-bit select signal 912. That is, port "0"
In the main scanning direction, the data in the main scanning direction is thickened by 1.5 pixels in the port “0”, and in the port “6”, the data in the main scanning direction is 1.
Can be processed by thinning by 5 pixels, -1.5 to 1.5
Up to pixels can be processed in 0.5 pixel units. Further, the binarized image signal input from the input unit 901 which has not been delayed is also latched / shifted by the flip-flops 908a to 908c, and the four data in the main scanning direction which have been latched / shifted are stored in the subsequent stage. The OR gate performs the thinning process, and the thinning process is input to the selector 909, and the same thickening / thinning process in the main scanning direction is performed. Then, the signals output from the selectors 907 and 909 are ANDed again.
It is input to the selector 910 through the / OR gate. The selector 910 performs thickening / thinning processing in the sub-scanning direction,
It is performed in the unit of one pixel of -1, 0, 1 pixel. As described above, after the CPU 42a automatically selects and performs the predetermined main scanning and sub-scanning correction amounts for the thickening process in the positive image mode and the thinning process in the negative image mode according to each mode, The ON / OF signal 440 to the laser driver circuit 280 shown in FIG. Laser driver circuit 28
0 performs processing for driving the semiconductor laser 26.
The semiconductor laser 26 converts the electric signal 450 from the laser driver circuit 280 into optical information, which is reflected by the rotary polygon mirror 25a and then latent image of red information is formed on the surface of the photosensitive drum 11. As described above, by performing multiple development,
It is possible to copy two colors, black and red.

Although the image formation of red information has been described in the present embodiment, the thickening / thinning processing can be similarly performed when a black binary image is formed.

Further, in the above embodiment, the case of executing the thickening / thinning process by the mode switching in the binary image has been described, but the thickening / thinning process is executed also in the multi-valued image as described later. It is also possible to do so.

FIG. 18 is a diagram showing a multivalued image information processing state in an image forming apparatus showing another embodiment of the present invention.

For example, in the case of the final multi-value density data as shown in FIG.
From 50 ”, up, down, left and right (254, 220, 96, 13
A value obtained by multiplying the data of Max value in the data of 6) by an arbitrary constant (tentatively 128/256) in the pixel of interest, that is, {250 + Max (254, 220, 96, 13)
6)} × 128/256 = 252 is set as the value of the pixel of interest (see FIG. 7B). It is possible to perform the thickening process by sequentially placing all the pixels in the target pixel in this 3 × 3 matrix. Further, in the case of thinning processing, as in the thickening processing, {250 + Min (254, 220, 9)
6, 136)} × 128/256 = 173 is set as the value of the pixel of interest (see FIG. 7C). It is possible to perform the thinning process by sequentially placing all pixels in the target pixel in this 3 × 3 matrix.

In this way, by performing the thickening / thinning processing by the 3 × 3 matrix processing, the negative / positive,
Proper image can be obtained regardless of image scan / background scan.

[0068]

As described above, according to the present invention, when the image output mode is selected by the mode selecting means, the amount of thickening performed by the image processing means on the image signal based on the image output mode selected by the setting means. Alternatively, the amount of thinning is adjusted to be set, and the exposure unit exposes the light beam to the photoconductor based on the image recording signal subjected to the thickening process or the thinning process to form an electrostatic latent image. It is possible to generate an image recording signal that reproduces a negative image and a positive image with an image quality close to the original, regardless of the exposure method. Further, the setting means selects and sets either the negative image output mode or the positive image output mode as the image output mode,
When the image processing unit is in the negative image output mode or the positive image output mode, the exposure unit causes the photoconductor to be exposed to the photosensitive member based on the image recording signal which is subjected to the optimum thickening process or thinning process corresponding to each mode for the image signal By exposing the light beam to form an electrostatic latent image, an image recording signal that optimally reproduces a negative image and a positive image can be generated.

Further, the image processing means automatically selects the thickening processing or the thinning processing for the negative image information or the positive image information based on the image exposure method for the photosensitive member by the exposing means, thereby The exposure means exposes the photoconductor to a light beam on the basis of the image recording signal obtained by performing the optimum thickening or thinning processing on the image signal by the image processing means without depending on the exposure method. By forming the latent image, it is possible to generate an image recording signal that is not affected by the exposure method.

Therefore, a negative image and a positive image can be obtained with an image quality close to that of the original.

[Brief description of drawings]

FIG. 1 is a cross-sectional configuration diagram illustrating an example of an image forming apparatus according to an embodiment of the present invention.

FIG. 2 is a block diagram illustrating a configuration of a controller unit shown in FIG.

3 is a plan view showing a latent image forming optical path to the photosensitive drum shown in FIG.

FIG. 4 is a circuit block diagram illustrating the configuration of the CCD line sensor shown in FIG.

5 is a block diagram illustrating a configuration of an image processing unit in the controller unit illustrated in FIG.

FIG. 6 is a schematic diagram showing a table configuration of a color determination table in the image forming apparatus according to the present invention.

FIG. 7 is a schematic diagram showing a table configuration of a color determination table in the image forming apparatus according to the present invention.

FIG. 8 is a schematic diagram for explaining the operation of the contact point extraction circuit shown in FIG.

9 is a diagram illustrating the operation of the expansion circuit shown in FIG.

FIG. 10 is a diagram for explaining the operation of the compression circuit shown in FIG.

11 is a schematic diagram showing an input / output relationship of the AND circuit shown in FIG.

12 is a timing chart showing a signal selection processing operation of the selector shown in FIG.

13 is a diagram showing a density signal extraction process by the selector shown in FIG.

FIG. 14 is a schematic diagram illustrating a combining operation of the combining circuit illustrated in FIG.

FIG. 15 is a schematic diagram for explaining the operation of the thickening / thinning circuit shown in FIG.

16 is a schematic diagram for explaining the operation of the thickening / thinning circuit shown in FIG.

17 is a circuit block diagram illustrating a detailed configuration of the thick / thin circuit shown in FIG.

FIG. 18 is a diagram showing a multi-valued image information processing state in an image forming apparatus showing another embodiment of the present invention.

FIG. 19 is a diagram showing a relationship between a pixel size and a laser spot diameter in this type of image forming apparatus.

FIG. 20 is a schematic diagram showing a formation state of an image portion and a non-image in the image forming apparatus of this type.

[Explanation of symbols]

 42 controller 45 laser section 42a CPU 42b ROM 42c RAM 270 thick / thin circuit 280 laser driver

Claims (3)

[Claims] 1. An image processing means for performing a predetermined image signal processing on an input image signal, a mode selecting means for selecting an image output mode for an image recording signal output from the image processing means, and this mode. Setting means for automatically setting the thickening amount or the thinning amount performed by the image processing means on the image signal based on the image output mode selected by the selecting means; An image forming apparatus comprising: an exposure unit that exposes a photoconductor to a light beam to form an electrostatic latent image based on an image recording signal that is processed and output. 2. The image forming apparatus according to claim 1, wherein the setting means selectively sets either a negative image output mode or a positive image output mode as the image output mode. 3. The image processing means automatically selects a thickening process or a thinning process according to the negative image information or the positive image information based on the image exposure method for the photoconductor by the exposing means. The image forming apparatus according to claim 1.