JPH02224461A - Contour extraction circuit - Google Patents

Abstract

PURPOSE:To prevent void occurred in a conventional device by extracting a prescribed number of picture elements before and after the leading and trailing of a picture signal relating to the main scanning direction and the subscanning direction equally so as to obtain a contour signal. CONSTITUTION:A contour internal signal is retarded by 2 picture elements respectively in delay elements 503, 504 comprising a shift register and 3 retarded picture data are supplied to exclusive OR circuits 511, 512 being components of an edge detection circuit 510 in the main scanning direction and an edge signal is generated. Thus, when a picture data retarded by 2 picture elements with respect to the existing picture data is taken as a noted picture data, edge signals each having one picture element width with an edge inbetween are obtained. When the original picture is subjected to central blanking processing by forming the edge signals having the edge inbetween, no void takes place even when a part of the background is formed at an acute angle.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a contour extraction device suitable for application to an electrophotographic image forming device that records image information using a laser beam or the like. In particular, the present invention relates to a contour extraction device that prevents white spots.

[Background of the Invention] As is well known, an image forming apparatus, for example, an electrophotographic copying machine for monochrome images, has a photoreceptor drum (which functions as a carrier for an image forming member 1), and a predetermined static image is attached to this image forming member. Forms an electrostatic latent image and uses a developer such as toner to
! This is a device that copies image information by creating and fixing it.

Such image forming apparatuses are equipped with microcomputers, and have become capable of relatively complex image processing. Among these image processes, as shown in FIG. 42, there is an image process in which only the outline of an image such as a character is left and the inside is whitened out and copied.

To perform this image processing, it is necessary to extract a contour signal corresponding to the contour of the image. FIG. 43 shows an example of a contour extraction device used for this contour extraction. Such processing for extracting the inside of an image will be referred to as hollow processing hereinafter. Therefore, FIG. 43 shows a conventional example of a hollow processing circuit for contour extraction.

As shown in the figure, this hollow processing circuit 500 has delay elements 541 and 543 that delay two pixels, and a delay element 542 that delays two pixels and four images.

Then, 1 regarding the image data obtained from the 3rd line.
, 3.5 pixel delay is supplied to the edge detection circuit 550 in the main scanning direction, and an edge signal in the main scanning direction of the image is formed. Edge detection circuit 55
0 is composed of an AND circuit 551 that ANDs image data separated by four pixels, and an exclusive OR circuit 552 that exclusively ORs the AND output and the image data of the pixel of interest.

Similarly, the image data of the first line and the fifth line are completely supplied to the edge detection circuit 560 in the sub-scanning direction, and an edge signal in the sub-scanning direction of the image is formed. As described above, the edge detection circuit 560 is composed of an AND circuit 561 that ANDs image data 5 lines apart, and an exclusive OR circuit 562 that exclusively ORs the AND output and the image data of the pixel of interest. I can do it.

Then, by combining the edge signals in the main and sub-scanning directions, an edge signal for the image is obtained. Therefore, an OR circuit 565 is provided.

For convenience of explanation, the hollow processing in a portion where the background has an acute angle as shown in FIG. 44(a) will be exemplified.

For the image shown in FIG. 44(a), the internal signal D1=D6 of the edge becomes as shown in FIG.
When processing is performed to extract only the edge portion in the main scanning direction from
El to E6 are obtained.

FIG. 5B shows an example in which the width of the edge is two pixels.

Among these edge signals, the edge signal corresponding to end point q is E4.

Edge signals in the sub-scanning direction are obtained by similar processing. The internal signals D1 to D6 become as shown in FIG. 45(b), and when processing is performed to extract only the edge portions in the sub-scanning direction from these internal signals D1 to D7, the edge signals as shown in FIG. 45(C) are obtained. E2'' to E4- are obtained.

Therefore, the edge signals E1 to E6 in FIG.
If the edge signals E2'' to E5'' in the figure are ORed for the corresponding lines, the total edge signals E2+E2'' and E in the main and sub-scanning directions as shown in FIG. 45(d) are obtained.
3◆E3', . . . are formed.

[Problems to be Solved by the Invention] If the above-mentioned hollow processing circuit 500 is used, image data of only the outline of the image can be obtained.
It can be copied as a hollow image as shown in Figure 2.

However, in the hollow image, particularly where the background portion is at an acute angle, that is, the portion shown by the dotted line in FIG. 42, the extracted contours are not continuous, resulting in so-called white spots. This is because, as is clear from the edge signal E5+E5'' corresponding to the end point q shown in FIG. 45, the outline of the end point q is not recognized as a contour.

Therefore, the present invention solves these problems and proposes a contour extraction device that can accurately extract contours from any image.

[Means for Solving the Problems] In order to solve the above-mentioned problems, the present invention provides a contour extraction device for extracting contour information of an image, in which rising and falling portions of an image signal in the main scanning direction and the sub-scanning direction are detected. The feature is that a contour (No. 5) is obtained by equally extracting predetermined pixels on the front and rear.

[Operation] If predetermined pixels before and after the contour, for example, one pixel, are extracted so as to include the rising and falling parts of the image signal,
The edge signal in the main scanning direction is as shown in Figure 2(c), and the edge signal in the sub-scanning direction is as shown in Figure 3(C).
)become that way.

If you combine them, it will look like Figure 3(d), so
Edge signals corresponding to the end point q and the contour of the image branching from the end point q are extracted.

Therefore, if an image is copied based on Edge No. 48, there will be no discontinuous portions of the contour and no white spots will occur.

[Example] Hereinafter, an example of the contour extraction device according to the present invention will be described in detail with reference to FIG.

4 and 5 show a schematic configuration of a circuit system of an image forming apparatus to which the present invention is applicable, and FIG. 6 shows a schematic configuration of a mechanical system thereof.

In Figure 4, this image forming bag! ! Reference numeral 10 includes a scanner section 10A, an image processing section 10B, and a printer section 10C.

The scanner part 10A refers to a series of processing systems for converting an optical image related to image information of a document obtained by optical scanning into an electrical image (No. 8).

The printer unit 10C is a printer that can print data based on the image signal finally output from the image signal unit (image data that has undergone PWM conversion or multi-value processing, etc.) or the binary print data that has been supplied from the outside. This refers to the processing system up to recording as a visual image.

In this example, the printer section 10C employs an electrophotographic recording method using an image forming member (photosensitive drum), and a semiconductor laser is used as the light source for forming the electrostatic latent image. Therefore, the printer section 10C is configured as an electrophotographic laser printer.

The image processing section 10B is a processing section for performing appropriate image processing on the input image signal, and includes hollow processing. In addition to the hollow processing, image processing such as scaling processing, filtering processing, shading processing, and PWM processing is performed.

FIG. 6 particularly shows an example of the mechanical part of the digital copying machine configured as described above.

The scanner part 10A will be explained first. By turning on the copy button provided on the digital copying machine, the original platen 8
1 is optically scanned by an optical system.

This optical system consists of a carriage 84. ■It is composed of mirrors 89 and 89°.

A halogen lamp is used as the light source. It is also possible to use a commercially available green fluorescent lamp instead of the halogen lamp, and in this case, the fluorescent lamp is turned on and driven by a high frequency power source of about 40 kHz to prevent flickering.

In addition, in order to maintain a constant temperature of the tube wall or promote warm-up, it is necessary to use a heater using a POSISTOR.

A standard white plate 97 is placed on the upper surface side of the left end of the platen glass 81.
is provided. This is to normalize the image signal (white signal) obtained by optically scanning the standard white plate 97 to a standard white signal.

The carriage 84 and the mirrors 89 and 89' are each caused to run on a slide rail (not shown) at a predetermined speed in a predetermined direction by a stepping motor 90.

An optical image (image information) obtained by irradiating the original 1 with the light source 85 is guided to the optical information conversion unit 12 via a reflection mirror 87 and a mirror 89. The optical information conversion unit 12 includes a lens 13 and a CCD on which an optical image is formed.
II, and the optical image is converted into an electrical signal (image signal).

The image signal is subjected to various image processing in the image processing section 10B and then output to the printer section 10C.

The printer section 10C has a deflector 935. Deflector 93
In addition to a galvanometer mirror, a rotating polygon mirror, etc., a deflector made of an optical deflector using crystal or the like may be used as the light beam 5. The laser beam that has been modulated by the image signal is deflected and scanned by this deflector 935.

When deflection scanning is started, beam scanning is successfully detected by a laser beam index sensor (not shown), and beam modulation using an image signal is started.

As image K (No. 8), image information (copy data) of the document 1 described above and print data are selectively used.

The modulated beam is caused to scan by a charger 121 over the image forming member (photosensitive drum) 110 which has been fully charged with a negative charge.

Here, the main scanning by the laser beam and the image forming body 110 are performed.
Due to the sub-scanning caused by the rotation of the image forming member 110, an electrostatic latent image corresponding to the image signal is formed on the image forming body 110.

The second electrostatic latent image is developed by a developer 123 containing black toner. A predetermined bias voltage from a high voltage power supply is applied to the current device 123.

A black and white pattern is formed by development.

On the other hand, the recording paper P fed from the paper feeding device 141 via the feed roll 142 and the timing roll 143 is
The image forming member 110 is conveyed onto the surface of the image forming member 110 while being timed with the rotation of the image forming member 110 . Then, by the transfer pole 130 to which a high voltage is applied from a high voltage power source,
The black toner image is transferred onto the recording paper P, and the separation pole 13
Separated by 1.

The separated recording paper P is completely conveyed to the fixing device 132, where it undergoes a fixing process and a monochrome image is obtained.

The image forming body 110 after the transfer is transferred to a cleaning device 126
is cleaned and prepared for the next imaging process.

In the cleaning device 126, a predetermined DC voltage is applied to a metal roll 128 provided on the blade 127 in order to facilitate recovery of the toner cleaned by the blade 127. This metal roll 128 is the image forming body 1
10 in a non-contact manner.

After the cleaning is completed, the blade 127 is released from the pressure bond, but in order to remove unnecessary toner that remains behind when the blade 127 is released, an auxiliary cleaning roller 129 is further provided, and this roller 129 is rotated in the opposite direction to the image forming body 110. By crimping, unnecessary toner can be thoroughly cleaned and removed.

The printer section 10C is an electrophotographic printer using a semiconductor laser as described above.

FIG. 7 particularly shows the main part of a deflection scanning system using a semiconductor laser.

A laser beam emitted from a semiconductor laser 931 enters a polygon 935 made of an octahedral rotating polygon mirror via mirrors 942 and 943. A laser beam is deflected by this polygon 935, and is irradiated onto the surface of the image forming body 110 through an f-θ lens 944 for imaging.

945 and 946 are cylindrical lenses for correcting inclination angles.

The polygon 935 directs the laser beam to the image forming body 110.
is scanned at a constant speed in a predetermined direction a.

The f-theta lens 944 is used to equalize the beam position on the imager 110.

A primary image is formed on the photoreceptor by normal negative/positive reversal development on the electrostatic Wa created as described above.

This situation is shown in FIG.

The figure shows changes in the surface potential of the image forming body 110, taking as an example the case where the charging polarity is positive. PH is the exposed area of the image forming body, DA is the unexposed area of the image forming body -roup
indicates the increase in potential caused by the adhesion of positively charged toner T1 to the exposed area PH during development.

The image forming body 110 is uniformly charged by the charger, and
A constant positive surface potential E is obtained. Image exposure using a laser as an exposure source is applied, and the potential of the exposed portion PH decreases in accordance with the amount of light.

The electrostatic latent image thus formed is developed by a developing device to which a positive bias approximately equal to the surface potential E of the unexposed area is applied. As a result, the positively charged toner adheres to the exposed portion PH, which has a relatively low potential, and a toner image is formed.

In the area where this toner image is formed, the potential increases by DUP due to the adhesion of the positively charged toner TI, but normally it does not have the same potential as the unexposed area DA.

Next, recorded image data is obtained by transferring the image to recording paper and fixing it by heating or applying pressure. In this case, the toner and charges remaining on the surface of the image forming body are cleaned and used for the next image forming body.

In addition to electrophotography, methods for forming latent images for image formation include methods in which charges are directly injected onto the image forming body using a multi-needle electrode, etc., and methods in which electrostatic latent images are formed by directly injecting charges onto the image forming body using a magnetic head. A method of forming an image, etc. can be used.

FIG. 5 shows a specific example of the image processing section 10B.

By supplying the image signal to the A/D converter 20,
It is converted into a digital signal of a predetermined number of bits, in this example 8 bits. Shading correction is performed simultaneously with A/D conversion. The shading correction circuit 21 is provided with a line memory 22, as shown in FIG.
The average signal is used as a reference signal for shading correction.

The shading-corrected DigiMole image (9 signals) is supplied to a filtering processing circuit 24, where it is subjected to filtering processing according to the image content.

For example, in the case of character drawings, the degree of disassembly (for example, MTF
), and for photographic images, filtering processing is performed to smooth the image signal to improve moiré.

This filtering process can be realized using, for example, a 3×3 convolution filter. An example is shown in FIG.

The figure particularly shows the case where it is configured as a cross filter,
A in the same figure is a filter for resolution correction, and B in the same figure is a filter for smoothing. Which filter to use is specified externally. This designation signal can also be generated automatically.

The numerical values shown in FIG. 10 are filter coefficients, but this is an example.

The MTF is the white signal (g, bell y, and black signal 48).
It is calculated from No. 8 level X using the following formula.

MTF-(y-x)/(y+x)X 100(%)MT
The reason for performing F correction is that the aperture size of the CCD II may be large in the sub-scanning direction, including deterioration of sharpness in the transmission system such as a lens, and that the signal is This is because MTF deterioration in the sub-scanning direction may be more significant than in the main-scanning direction in order to obtain this, so it is necessary to correct these factors.

By performing MTF correction processing, skipping and blurring of characters can be corrected.

The filtered image data is subjected to extraction/erasing/filling processing for a specific area in the signal processing means 300.

These processes and the above-mentioned filtering process are all executed within or outside the specified area, so in order to perform these processes, it is necessary for the area detection circuit 25 to detect the specified area.

To detect the designated area, use position designation paper (blank paper) as shown in Figure 11.
This is done based on the marker M written on 2. Therefore, before the main scanning of the original 1, the position specifying paper 2 is placed on the original platen 81 and preliminary scanning is performed, thereby detecting the area.

The region may be designated as a rectangle as shown in the figure, or any shape as shown in FIG. 12.

Various methods can be used to detect the area, so a detailed explanation thereof will be omitted, but in this example, the method shown in FIG. 13A is used.

As shown in B, the next area signal Qi (E in the same figure) is formed from the area No. 18 Q i-1 detected immediately before and the marker signal Ri. Therefore, the AND of the two is taken as shown in C in the same figure, and then the internal signal of the marker is created based on this AND output (D in the same figure). A region signal Qi on the i-line as shown in FIG.

The area signal Q thus formed is supplied to a signal processing means 300 that performs extraction/erasing/filling. At this time, follow the directions inside/outside the marker area.

FIG. 14 shows an example of the signal processing means 300, in which the image signal supplied to the terminal 301 is sent to the selector 302.
and is converted into image data corresponding to a processing designation signal such as image deletion. Therefore, this selector 302
A control signal forming circuit 310 is provided in connection with.

As shown in the figure, the control signal forming circuit 310 is composed of three NAND circuits 311 to 313 and a NAND circuit 314 to which the output thereof is supplied, and the NAND circuits 311 to 3 on the input side.
13, in addition to the corresponding processing designation signals, the area 48
No. R is commonly supplied.

Then, in °°filling °°, the output of the NAND circuit 311 for all black processing designation is supplied to the input side of the selector 302 together with the image data, and the selector 302 is controlled by a control signal that is the output of the NAND circuit 314.

In the figure, the control signal is selected to be input to the side b of °°H°°.

When °°extraction°° processing is designated as the processing designation signal, image data will be output only while this is being obtained, and the same goes for °° deletion.

During processing, the output of image data is blocked only during that time.
In the process specification of full filling, a signal of 1° (predetermined DC voltage) is output as image data instead of the input image data.

The image signal and area signal R that have been subjected to predetermined signal processing are supplied to a scaling processing circuit 30 and subjected to enlargement/reduction processing as necessary.

The scaling process is performed in the main scanning direction by electrical processing of interpolating image signals, and in the sub-scanning direction by mechanical processing of changing the scanning speed of the scanner part 10A.

The scaling factor is 50 to 400%, and the reason why the area signal R is also supplied to the vertical product independent scaling type scaling processing circuit 30 is that the area signal R also needs to be scaled in accordance with the scaling factor.

The image @ signal subjected to scaling processing is then sent to a background pattern processing circuit 400
can be supplied to. One type of tint pattern is shading.

The reason why a tint block is applied after the scaling process is completed is that the pitch of the designated tint block should remain unchanged even after the scaling process.

Examples of tint pattern patterns are shown in FIGS. 15(1) to 15(7).

In order to output such pattern data, the 16th
As shown in the figure, these pattern data are stored in a tint pattern data ROM 401 and can be selected from the outside.

Therefore, a column address counter 402 and a row address counter 403 are provided for the tint pattern data ROM 401, and the column address of the tint pattern data ROM 401 is specified by the counter output incremented by a signal corresponding to A3 size, for example. The row address of the copy-forgery-forgery-forgery-inhibited data ROM 401 is designated by the output of a counter incremented by the clock CK synchronized with the bell.

Background pattern data obtained by address specification (8
x8 matrix mesh pattern data) is ORed with image data in an OR circuit 404 to obtain image data after copy-forgery-inhibited patterning.

The area signal R and tint pattern designation signal are supplied to an AND circuit 405, and the tint pattern data ROM 401 is chip-selected by its output.

As a result, as shown in FIG. 17, when the background pattern designation signal is obtained, the background pattern designation signal R is applied only to that designated area.
The tint block pattern data of OM401 becomes valid.

The repetition of address designation for the tint block data ROM 401 can be determined by the repetition period of the tint block pattern.

Before proceeding to tint block processing, dither processing may be performed to emphasize the halftones of the image data.

The image data after the copy-forgery-inhibited pattern is then subjected to hollow processing.

FIG. 1 shows an example of a hollow processing circuit 500 that prevents white spots, and is designed to extract image data for a contour signal symmetrically inside and outside an edge to create an edge signal.

In this example, an example will be described in which equal pixels are extracted one pixel at a time across edges, but the number of pixels to be extracted is arbitrary. Also, for convenience of explanation, the image data is 2 bits (therefore,
4-value data) is configured. 1 pixel is 8
Since it is made up of bits, the hollowing process is executed in parallel for each pit.

First, the image data is supplied to the 5-line memory 35 shown in FIG. 5, from which the original image data and the image data delayed by 1.3 and 5 lines, respectively, are output.

Each image data is processed by the hollow processing circuit 500 shown in FIG.
is supplied to An example of the original image is shown in FIG. 44(a). This is reproduced in FIG. 2(a).

In the case of the original picture in Figure 2 (a), each line a1 to Q
, 6, a contour internal signal as shown in FIG. 6(b) is obtained. The contour internal signals are delayed by two pixels each in delay elements 503 and 504, which are constructed of shift registers, etc., and the delayed three image data are sent to exclusive OR circuits 511+512 that constitute an edge detection circuit 510 in the main scanning direction. The edge signal shown in FIG. 3(c) is formed.

Therefore, if the image data delayed by two pixels with respect to the current image data is the image data of interest, edge signals each having a width of one pixel between the edges are obtained by the above-described processing.

Next, the image data of the first line and the fifth line are supplied to corresponding delay elements 501, 502, 505, and 506, and are each delayed by two pixels relative to the current image data. The 1 and 3.5 lines of image data (FIG. 3(b)) outputted from these are supplied bit by bit to the edge detection circuit 520 in the sub-scanning direction.

Since the edge detection circuit 520 is also constituted by an exclusive-OR circuit, the edge signal shown in FIG. 4C is generated from these circuits. This edge signal also has a convergence of one pixel before and after the edge of the original image.

Therefore, if the edge signals in the main scanning direction and the edge signals in the sub-scanning direction are logically summed by respective OR circuits 525+526, a total edge signal as shown in FIG. 3(d) can be generated.

In this comprehensive edge signal, as is clear from examining several lines from line Ω3 where end point q exists, edge signals related to edges including end point q are continuously generated.

In this way, if the edge signals are formed to sandwich the edges and the original image is hollowed out, no white spots will occur even if the background part is at an acute angle like the end point q, as shown in Figure 42. . It is preferable to express the contour with a radius of about 2 bells at both ends of the edge portion (total of 4 bells).

The output of the hollow processing circuit 500 undergoes image inversion processing in the inversion circuit 40, and is then supplied to the gamma correction circuit 45. Gamma correction circuit 45 is part of scanner 10A
This is provided to ensure consistency between the printer unit 10C and the printer unit 10C.

FIG. 18 shows the characteristics between the scanner part 10A and the printer part 10C, and the first quadrant is the printer part 10C.
The 1st I quadrant shows the density characteristics after copying, the 111th quadrant shows the conversion characteristics of the scanner part 10A, and the 2nd quadrant shows the gamma correction characteristics.

Therefore, the optical density of original 1 is 1°O' in the scanner part.
A is converted into a predetermined image signal (111th quadrant)
, when a predetermined gamma characteristic is given to this image signal (the first
■ Quadrant), the image signal is pulse width modulated (PWM) output according to this gamma characteristic (1st V quadrant), and the image is
Since recording is performed according to the WM modulation output, the copy density is determined by this recording characteristic (first quadrant).

As a result, the relationship between the density of the original and the density of the actual copy becomes like the characteristics of the 1st I quadrant.

As is clear from the characteristics of the 1st I and 2nd quadrants,
For manuscripts with text, it is better to make the gamma characteristic steep as shown in the figure. This is because a low density region with an optical density of about 0.1 to 0.4 is important for character reproduction.

On the other hand, for photographic areas, it is better to have a slower gamma characteristic. This is because gradation reproduction is important. Usually, F=1 is selected.

If this is not done, flying in low density areas will cause collapse in high density areas.

Further, even for the same character portion, various specific curves can be selected for the gamma characteristics. The selection can be made in the following ways.

In this example, two cases are exemplified, one in which the density of the document is automatically detected and the gamma characteristics are set, and the other in which the gamma characteristics are manually set.

First, filtered image data is supplied to an automatic density setting circuit (EE circuit) 50 to perform density detection.

This can be done, for example, by determining the type of image by determining the spread of density information (preliminary scanning is performed to create a density histogram of original 1 (see Figure 19). From the density histogram, the maximum density and minimum density of original 1 are determined. and the background level are determined, and a selection signal for selecting a gamma correction curve suitable for the original is generated from these. After this selection signal is selected by the selector 55, it is supplied to the gamma correction circuit 45.

On the other hand, the gamma correction curve is also selected by the manual selection signal supplied to the terminal 57.

The gamma-corrected image data is subjected to mirror image processing in the mirror image processing circuit 60 when specified from the outside, and then the selector 70 combines the image data (8 bits) and 1 bit sent from the external print data controller 65. binary data is selected.

This binary data is print data, and for example, data generated by a Japanese word processor or the like is input. Therefore, this image forming value M10 has a printing function for the external print data controller 65 in addition to the copying function of the original 1.

Since the image data is 8 bits and the print data is 1 bit, the input ports QAO to A6 of the input ports AO to A7 of the selector 70 are grounded when the data is print data.

Which function to select depends on external designation.

The selected image data (8 bits or 1 bit) is supplied to a PWM modulation circuit 600 shown in FIG.

In this example, gradation processing using luminance modulation is exemplified instead of area gradation processing. Therefore, 8-bit image data is
After being converted into an analog signal by an A converter 601, analog comparison is performed using a reference signal such as a triangular wave or a ramp wave outputted from a generating circuit 602. The reference signal is repeated for each pixel (FIG. 21A).

When the reference signal is a triangular wave, when the level of the image data to be referenced is as shown in Fig. 21 A, the level of the image data to be referred to is as shown in Fig.
, C can be obtained, and if a semiconductor laser (described later) is modulated with this, the same figure can be obtained.
Since the luminescence level (brightness level) is as shown in E,
This means that the shading of the pixel is brightness-modulated (intensity-modulated).

The reason for adopting such intensity modulation will be described below.

First, when recording with normal laser power (1.0 to 3.0 mW), the curve La=
The curve of Lc (curve 7) becomes very steep. This is a binary recording, and a recording format in which the width of the black dot changes with PWM output. However, in order to actually change the black dot width by PWM output, the period of the reference signal needs to be at least two dots or more.

There is no particular problem with using a reference signal with a period of two dots or more for gradation images, but when attempting to reproduce character images, line skipping becomes noticeable and character quality deteriorates. Therefore, in this example, both character images and gradation images can be sufficiently reproduced even with a one-dot cycle reference signal.

In order to do this, even with one-dot multilevel modulation, the broken line L in Figure 23 must be
It is sufficient if the γ curve approaches 7=1, as shown in d. To do this, the laser power of the semiconductor laser 931 constituting the developing means may be lowered than usual, for example, to about 0.5 mW (see the broken line curve III in Fig. 23).
(See A).

In order to bring 7 roughly close to 1, one or both of the charging means and the developing means may be controlled as desired. In this example, both the charging voltage Vl applied to the charger 121 for the image forming body 110 and the developing bias voltage VB supplied to the developing device 123 are adjusted to be higher than normal.

Typical examples are shown in Table 1, and the recording characteristics are shown in the solid curve in Figure 23.

Table-1 V)l VL Laser power Normal 600V 480V 2mW Example 700V 580V 0.5mW 24th
The figure shows an example of the printer section 10C.

In the same figure, a semiconductor laser 931 has its driving circuit 9.
32 is provided, the above-mentioned image data is supplied to this drive circuit 932 as a modulation signal, and the laser beam is internally modulated by this modulation signal 48. Laser drive circuit 93
2 is controlled by the control signal ti1!148 from the timing circuit 933 so that it is in the driving state only in the horizontal and vertical effective area sections. A signal indicating the amount of light of the laser beam is fed back to the laser drive circuit 932, and the driving of the laser is controlled so that the amount of light of the beam is constant.

The scanning start point of the laser beam deflected by the octahedral polygon 935 can be detected by the index sensor 936, and the index signal is converted into a voltage signal by the I/V amplifier 937. CPU251 controls the timing system
(FIG. 25) to control the timing of optical scanning, etc.

934 is a polygon motor drive circuit;
The off signal is supplied from timing circuit 933.

The various devices or circuits described above are all controlled by first and second control sections 200 and 250, as shown in FIG. The explanation will start from the second control unit 250.

The second control unit 250 mainly controls the scanner part 10A and its peripheral equipment, and is 251
is an optical drive control microcomputer (second microcomputer) 201, and various information signals are exchanged with the main body control microcomputer (first microcomputer) 201 through serial communication. Further, the optical scanning start signal 48 sent from the first microcomputer 201 is directly supplied to the interrupt terminal of the second microcomputer 251.

The second microcomputer 251 generates various commands 18 in synchronization with a clock of a predetermined frequency (12 MHz) obtained from the reference clock generator 254.

The second microcomputer 251 outputs the following control signals.

First, a control signal to turn on and off the drive circuit of CCDI 1 is provided to its power supply control circuit (not shown). Second, a predetermined control signal is supplied to a lighting control circuit 253 for a light source 85 for irradiating the document with necessary light. Thirdly, the carriage 84 and the V mirror unit 8
Stepping motor 90 for moving 9.89-
A control signal is also supplied to a drive circuit 252 that drives the.

Data indicating the home position is input to the second microcomputer 251.

The first microcomputer 201 is mainly used to control the printer section 10C.

An example of an input system and an output system related to this is shown in FIG.

The operation/display unit 202 receives input data such as magnification designation, recording position designation, and recording color designation, and displays the contents thereof.

As the display means, an element such as an LED is used.

The paper size detection circuit 203 is used to detect and display the size of the cassette paper loaded in the tray, or to automatically select the paper size according to the size of the document.

The cassette zero sheet detection sensor 220 detects whether there are no sheets in the cassette. Similarly, the manual feed zero sheet detection sensor 222 detects the presence or absence of paper for manual feed in the manual feed mode.

The toner density detection sensor 221 detects the density of toner on the drum 110 or after fixing.

Further, the remaining amount of toner is detected by the toner remaining amount detection sensor 223.
The remaining amount of toner 23 is detected, and when toner replenishment is necessary, a display element for toner replenishment provided on the operation section is controlled to light up.

- The time stop sensor 224 is for detecting whether or not paper is correctly fed from the cassette to the second paper feed roller (not shown) during use of the copying machine.

Contrary to the above, the paper ejection sensor 225 is used to determine whether or not the fixed paper is correctly ejected to the outside.

The manual feed sensor 226 is used to detect whether a manual feed tray is set. If it is fully set, it will automatically switch to manual feed mode.

The sensor output obtained from each sensor as described above is taken into the first microcomputer 201, and necessary data is displayed on the operation/display unit 202, and the driving state of the copying machine is controlled as desired. .

In the case of copying, a developing motor 227 is provided, and these are all controlled by command signals from the first microcomputer 201. Similarly, the driving state of the main motor (drum motor) 204 is controlled by a drive circuit 205 having a PLL configuration, and this drive circuit 205 is also
Its driving state is controlled by a control signal from the microcomputer 201.

During development, it is necessary to apply a predetermined high voltage to a developing device or the like during development.

Therefore, a high-voltage power source 228 for charging, a high-voltage power source 229 for development, a high-voltage power source 230 for transfer and separation, and a high-voltage power source 231 for toner receiver are respectively provided, and when necessary, a predetermined high-voltage power source 231 is provided for each of them. A high voltage will be applied.

Note that 233 is a cleaning roller drive unit, 234 is a first paper feed roller drive unit, 235 is a second paper feed roller drive unit, and 232 is a cleaning pressure release motor. Furthermore, 236 is a drive unit for the separation claw.

The second paper feed roller is used to transport the paper transported by the first paper feed roller to the electrostatic latent image formed on the drum 110.

The fixing heater 208 is controlled by a fixing heater on/off circuit 207 according to an @ control signal from the first microcomputer 201 .

The fixing temperature is read by the thermistor 209, and the first microcomputer 2
It, IJill is done by 01.

206 is a clock circuit (approximately 12 Mflz).

A nonvolatile memory 210 provided along with the first microcomputer 201 is used to store data that should be preserved even when the power is turned off. for example,
This includes total counter data and initial setting values.

In this way, the first and second microcomputers 20
1.251, various controls necessary for image formation are executed according to a predetermined sequence.

FIG. 27 is a timing chart showing an outline of when recording an image. A detailed explanation thereof will be omitted.

Next, the operation/display section 202 of this device will be explained with reference to FIG. 28.

(A) is a copy switch, and by pressing this switch, a copying operation is performed in the above-described sequence. There is also an LED below this switch, the red LED
While lit, it indicates the warming up time, and the ready state is reached only when the green LED lights up.

(B) is a display section that displays the number of copies, self-diagnosis mode, or indicates an abnormal state or its location. ? Segment LE
It consists of D and its contents are displayed numerically.

(c) is a group of keys for setting the number of copies, etc., instructing the self-diagnosis mode operation, interrupting the copying operation, clearing the set number of copies, etc.

For example, by pressing number keys 4 and 7 and turning on the power switch, it is possible to enter the self-diagnosis mode, and by inputting a specific number at this time, for example, the motor of the developing unit can be rotated independently. Is possible.

From this mode, it is possible to return to normal mode by inputting a specific number, or by turning the power off and then turning it on without pressing any keys.

In the normal mode, normal copying operations are possible, but by combining the numeric keys and the P button, operations such as printing out data and printing out test patterns are also possible.

For example, you can print out a test pattern in memory. When the stop/clear key is pressed during a copy operation, the process moves to a post-rotation process operation, and after this operation is completed, the initial state is returned. The same holds true when making multiple copies.

The key (d) is a key for selecting character image processing and photo image processing.

(H) is a key for instructing to perform area detection on the entire screen or on a portion of the screen, and when this key is pressed, a marker area on the document is detected.

The designation of inside/outside the marker area and the entire screen is changed each time the (g)' key is pressed.

On the other hand, the key group (l) is the key for specifying processing.

The key (e) is a key for selecting EE mode and manual mode. In EE mode, it becomes effective when a character is selected. (E) The 'key selects the gamma correction curve. In this case, seven different curves are prepared.

The (G) key is the key to select the paper feed size, and is B5.
You can choose from R to A3 size and postcard size.

The () key is used to select whether to use it as a printer or as a copy.

The (nu) key is a key for distinguishing online/offline in print mode.

The (wo) key selects between portrait and landscape in print mode.

In addition, using the functions described above, it is possible to perform various types of image processing as described below.

, anti-5JB=RIJHini-
Press the "Reverse" key to copy (see Figure 29).

When partially copying, specify the inside/outside of the marker and then press the "reverse" key to copy (see FIG. 30).

° 1 + - For example, press the marker "inside" key to copy (see Figure 31).

) After specifying the mode ``Full screen'', press the ``shading'' key and copy (see Figure 32).

After specifying the ``inner'' key with the marker, press the ``shading'' key and copy (see Figure 33).

After specifying "Full surface", press the "Outline (center cut)" key,
Then press the copy key (see Figure 34).

After specifying within the marker, press the r middle blank key, then specify shading and press the copy key (see Fig. 35).

亙】Old 1 Rij! After specifying a marker, press the reverse key to copy (Fig. 36).

The variable 5-1 plate (wa) is a key for setting fixed and vertical/horizontal zoom magnifications. By pressing this key or -, the LED is turned on or off and processing for the specified magnification is set. The image is copied at the same magnification (FIGS. 37 and 38).

When changing the zoom by setting the desired magnification,
Press the (W) key, select "Cirth magnification/Horizontal magnification", and select the magnification using the (Power) key.

Set the fixed magnification with (W), and use the (F) key to set the fixed magnification.
By selecting a magnification from size 5 to size 84, it is possible to set a fixed magnification of the same magnification in the vertical and horizontal directions.

On the other hand, in this state, if you press (wa) to select vertical and use the (strength) key to select magnification, horizontal will be the first magnification and fir will be the subsequently set magnification, making it possible to achieve vertical/product independent magnification.

Conversely, pressing the horizontal key instead of the vertical key has the same effect.

In a different method, the user may first press the ``vertical'' key to set the fir magnification, and then press the ``horizontal'' key to set the magnification.

-a After specifying within the marker, press the "Extract" key and copy (see Figures 39 and 40).

The above function is the opposite of the extraction processing mode (see Figure 41).

By using the key switch group (c), it is possible to instruct various operations for operation confirmation. For example, (I) 6χP: Scanner check 60P+copy; light source (halogen lamp) turned on, scanner optical system stopped, 1+copy in this state; halogen still on, optical system only at a speed slower than the normal speed in the sub-scanning direction. Move.

However, when the copy switch is turned off, the optical system will stop at that position with the halogen on 2+copy; Same function as 1+copy, but the optical system will move in the opposite direction 3+copy; Regular scanning will continue with the halogen on. 61P+Copy; With the halogen turned off and the scanner optical system stopped, pressing 1 to 6+Copy in this state will cause the same operation as above.

This operation is canceled by pressing the stop/clear key. Further, during each operation, image data is output from each circuit, making it possible to check the signal level.

(II) 7XP: Printer section check 70P+copy; only the polygon motor rotates and the laser is turned on. Index signal can be checked; in this state, 1+copy; print data controller output 2+copy; test pattern data output 3+copy;
Patch data can be output 71P+copy; Check mode related to recording section, 1+copy in this state; Charger on 2+copy; Developer motor on, developing bias on 5+copy; Transfer pole on 6+copy; Cleaning blade crimping 7+copy; Cleaning Blade release 8+copy; cleaning roller application (voltage) 9+copy; separation pole on 10+copy; first paper feed motor on 11+copy; second paper feed motor on, etc. In this case, this mode is canceled by pressing the stop/clear key in the same manner as described above.

This type of self-diagnosis check is not limited to this example, and it is possible to perform such self-diagnosis checks, making it easier for service personnel to perform maintenance in the market, or by having users perform a simple check before going for maintenance. will be able to respond more quickly.

[Effects of the Invention] As explained above, according to the present invention, a contour signal is obtained by equally extracting predetermined pixels before and after the rising and falling parts of the image signal in the main scanning direction and the sub-scanning direction. It is something.

According to this, it is possible to reliably extract the outline of the image including the end points. Therefore, whether the background part has an acute angle or
Regardless of whether there is a contour or not, extracting the outline of the image eliminates the white spots that occur in conventional methods.

Therefore, the contour extraction device according to the present invention is extremely suitable for application to image forming apparatuses such as the above-mentioned electrophotographic copying machine.

[Brief explanation of the drawing]

FIG. 1 is a system diagram showing an example of a hollow processing circuit which is a contour extraction device according to the present invention, FIGS. 2 and 3 are waveform diagrams for explaining its operation, and FIG. 4 is a diagram to which this invention can be applied. FIG. 5 is a system diagram of the main parts showing an example of an image forming apparatus, FIG. 5 is a system diagram of the image processing section thereof, FIG. 6 is a schematic configuration diagram of an electrophotographic copying apparatus applicable to the present invention, and FIG. 7 is a deflection diagram. The configuration diagram of the scanning system, Figure 8 is an explanatory diagram of the image forming process, Figure 9 is a diagram of the shading correction circuit, Figure 10 is a diagram of the filtering process, and Figures 11 and 12 are explanations of area extraction. 13 is a waveform diagram for explaining region extraction, FIG. 14 is a system diagram of the signal processing means, FIG. 15 is an explanatory diagram of the tint block pattern, and FIG. 16 is a system diagram of the tint block processing circuit means. Figure 17 is its operating waveform diagram, Figure 18 is a curve diagram showing the overall characteristics of the image forming apparatus, Figure 19 is a density histogram characteristic diagram, Figure 20 is a system diagram of the PWM modulation circuit, and Figure 21 is its operation. A waveform diagram for explanation, Fig. 22 is a curve diagram of recording characteristics against laser power, Fig. 23 is a curve diagram showing the relationship between charging voltage and recording characteristics, Fig. 24 is a system diagram of the printer section, and Fig. 25 is a curve diagram showing the relationship between charging voltage and recording characteristics. Block diagram of the second control unit, the second
FIG. 6 is a configuration diagram of the first control section, FIG. 27 is a waveform diagram for explaining its operation, FIG. 28 is a diagram showing the key layout of the operation/display section, and FIGS. 29 to 41 are FIG. 42 is an explanatory diagram of a key operation process, FIG. 42 is an explanatory diagram of a blank area, FIG. 43 is a system diagram of a conventional hollow processing circuit, and FIGS. 44 and 45 are explanatory diagrams of its operation. 10 ・ 10A ・ 10B ・ 10, C ・ 11 ・ 24 ・ 30 ・ 40 ・ 45 ・ 50 ・ 60 ・ 65 φ 110 ・ Image forming device Scanner Partial image processing section Printer section CD Filtering processing circuit Magnification processing circuit Inversion processing circuit Gamma correction circuit Automatic density adjustment circuit Mirror image processing circuit Print data controller Image forming body 300 ・ 400 ・ 500 ・ 600 : Hollow out processing circuit Figure 1 (b) Original image data (C) Edge data (main scanning direction) 10: Ii image forming device Figure 4 (c) Edge data (sub scanning direction) (d) Total edge data 21: Shading correction Circuit MTF correction smoothing No. 13 Diagram divination: I word No. 1 Physician Figure 14 Boo: PWM modulation circuit Figure 19 Figure 22 Figure 23 tOC: Printer section Figure 24 (b) Original image data (c) Edge data (main scanning direction) (a) Original image (b) Original image data (c) Edge data (sub scanning direction) (d) Total edge data

Claims (1)

[Claims] (1) In a contour extraction device that extracts contour information of an image, a contour signal is obtained by equally extracting predetermined pixels before and after the rising and falling portions of the image signal in the main scanning direction and sub-scanning direction. Characteristic contour extraction device.