JPS616672A - Image processor - Google Patents

Abstract

PURPOSE:To reduce the size of the image processor and improve the precision of a copy image by providing an eraser means which irradiates only a no-image area on a photosentive body detected by an original information detecting means with light. CONSTITUTION:The eraser 41 illuminates corresponding to respective picture elements of the photodedector group 71 of a reflection density detector 35, and LEDs of the eraser 41 which correspond to the no-image area obtained from image density stored in a ROM56 are turne on according to copy magnification, thereby preventing the sticking of toner. Further, LEDs of the eraser 41 which correspond to picture elements on the border between the no-image area and an image area to prevent the sticking of toner. A judgement of a set of picture elements of an edge of a book is mode until the detector 35 detects a white standard higher than a prescribed reflection factor after detecting an original edge, and LED of the eraser 41 which correspond to the set of edge picture elememts are turned on the prevent the sticking toner. When MP55 judged that half-tone originate from the fold of the book, the eraser 41 prevents the sticking of toner. When there is a character, etc., near the border, reduction control is carried out, so no influence of the eraser 41 is exerted.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an image processing device that detects document information of a document placed on a document support stand.

[Prior art and its problems]

Conventional image processing apparatuses include a detection means that detects the density of a document placed on a document support table and controls the copy density to an appropriate density, and controls such as automatic cassette selection (APS) or automatic magnification selection (AMS). Since the document size detecting means for performing the detection was provided independently, the structure was complicated and expensive.

[Purpose of the invention]

This invention was made to eliminate the above-mentioned drawbacks, and uses a group of light-receiving elements to detect the original information (original density, original position, original size, etc.) of the original placed on the original support stand, and accurately It is an object of the present invention to provide an image processing device that can form a good copy image in a set copy area (image area), has a simple configuration, and is inexpensive.

〔Example〕

FIG. 1 is a schematic sectional view showing an embodiment of an image processing apparatus according to the present invention, FIG. 2 is a control circuit diagram, and FIG. 3 is a front view of a reflection density sensing element.

In FIG. 81, 1 is a drum, 2 is a pre-static charger, 3 is a primary charger, and 4 is a charger, which performs corona charge removal on the drum 1. 5 is a copying charger, 6 is a cleaning device,
Consists of a cleaning roller and an elastic blade. 7 is a developing device, and 8 is a pre-exposure lamp, which eliminates static electricity from the drum 1. 9
is a full-surface exposure lamp which forms an electrostatic latent image on the drum 1.

10. Reference numeral 11 is a paper feed roller, and 12 is an upper cassette in which copy paper is stored. 13 is also the lower cassette, 14
15 is a registration roller, 15 is a transport belt, 16 is a fixing roller, 17 is an ejection roller, 18 is a tray, 19 is an original table glass, 20 is an original, 21 is an original pressure plate, and the surface in contact with the original 20 is a mirror surface or has a low reflectance. The parts are coated. 2
2.23 is a standard white plate, 24 is a moving optical system unit, which is composed of an irradiation lamp 25 and a first scanning mirror 26. 27 is a second scanning mirror, and 28 is a position detection piece, which is provided outside the moving optical system unit 24. Reference numeral 29 denotes a switch for detecting the contact state between the original pressure plate 21 and the original platen glass 19, which constitutes the book copy detection means of the present invention. 30°31.32 is a position sensor, position detection piece 2
8 is detected. 33 is a slit, 34 is the Sl scanning mirror 26. A document detection lens 35 forms an image of the reflected light guided by the second scanning mirror 27, and 35 is a reflection density lens in which a group of light-receiving elements such as COD are arranged in a row in the main scanning direction B (perpendicular to the sub-scanning direction A). The manuscript information detecting means 9 of the present invention is a detector.
Image area detection means.

It constitutes a reflection density detection means, and the document platen glass 19
The document size of the document 20 placed above, the image area within the document, the reflection density of the document, and the document position within the copyable area are detected. 36 is a projection lens that forms an image of the reflected light guided to the second scanning mirror 27, 37 is a third scanning mirror, 38 is a fourth scanning mirror, 39 is an optical system drive motor,
The moving optical system unit 24 is driven. A main motor 40 drives the drum 1. Reference numeral 41 denotes an eraser constituting the eraser means of the present invention, which prevents toner from adhering to the non-image area portion of the drum 1. This eraser 41 is composed of a group of LEDs that emit light corresponding to one pixel of the light receiving element group of the reflection density detector 35. Therefore, the erasers 41 are also arranged in a line in the main scanning direction B.

In the control circuit shown in FIG. 2, 51 is an oscillator that oscillates a clock signal. 52 is a frequency divider, 53 is an amplifier for amplifying the detection signal of the reflection density detector 35, and 54 is an A/D converter, which converts the output of the amplifier 53 into A/D and outputs the digital value to each input port iI to i4. Output to. 55 is a microprocessor (MP) which receives each sensor output 9 and the output of the reflection density detector 35 and each timing signal at each input port;
Each control signal is output from each output port. This MP55
is equipped with an internal timer, and also includes copy density setting means, automatic copy magnification adjustment means, eraser control means,
It also serves as a copy magnification setting means. 56 is the MP
RAM randomly accessed by 55, 571-
A cassette size input key 573 constitutes copy paper size detection means of the present invention, and inputs the cassette size to each input port 19 to i++ of the MP55. 58 is an input key such as a copy start key, numeric keypad, clear key, etc., which outputs a copy start signal and a copy number signal.

Clear signal etc. to each input port 113~ft6 of MP55
Enter. Reference numeral 59 denotes a D/A converter that performs D/A conversion of lamp signals to the irradiation lamp 25 that the MP 55 outputs to each output port 013 to 016.

6o is an amplifier that amplifies the lamp signal, and 61 is a lamp regulator (CVR) that controls the voltage of the irradiation lamp 25. 62 is a drive driver, which receives the eraser drive control signal outputted by MP55 to each output capo OL"09 and drives the eraser 41. 63 is a drive driver,
55 receives the motor drive control signals outputted to each output port 021 and 022, and drives the optical system drive motor 39.

641 is an AND circuit that ANDs the output signal of the frequency divider 52 and the control signal outputted from the MP55 to the output port 012, and outputs the shift pulse signal (SH) to the reflection density detector 3.
Enter 5. 642 is an AND circuit which similarly ANDs the output signal of the frequency divider 52 and the control signal outputted to the output port 0□1 by the MP55, and inputs the clock signal φl to the reflection density detector 35. 651 is an inverter that inverts the signal from the oscillator 51, and 652 is an AND circuit that performs an AND operation between the frequency divider 52 and the inverter 65□.
The D in signal is input to the input capo-1-iS of the MP55. 66 is the clock signal φ of the AND circuit 642.
A clock signal φ2 is input to the reflection density detector 35 by an inverter that inverts the clock signal φ2.

67 is a clock signal input to the input port i6 of the MP55. Note that the output of the switch 29 is input to the input port 112 of the MP55.

In the reflection density detector 35 shown in FIG. 3, 71 is a light receiving element group consisting of light receiving elements (1 to N), which are arranged in a row and divide the reflected light from the entire area in the main scanning direction of the original into parts 1 to N. It receives light and outputs an output voltage (V) corresponding to the reflection density (CD) as shown in FIG.

Next, document exposure and copying operations of the image processing apparatus will be explained with reference to FIGS. 1 and 2.

The surface of the drum 1 is a photoreceptor, and the main motor 4 is activated when the copy start key of the input key 58 is turned on.
0 starts rotation in the direction of the arrow. Due to this rotation, the original 20 placed on the original platen glass 19 (hereinafter, the light-receiving surface of the original platen glass 19 will be referred to as an image area) is slit-exposed by the irradiation lamp 25 integrated in the optical system moving unit 24. The reflected light is transmitted to the first scanning mirror 2.
6 and a second scanning mirror 27. By moving the first scanning mirror 26 and the second scanning mirror 27 at a speed of 1:1/2, the original 2o is scanned while the optical path length in front of the projection lens 36 is always kept constant, and the moving optical system The unit 24 is driven by an optical system drive motor 39. At this time, the slit 33. Projection lens 36. Third
Scanning mirror 37. The reflected image passing through the fourth scanning mirror 38 is
A high-contrast electrostatic latent image is formed via the charger 4 on the drum 1, which has already been simultaneously neutralized by the pre-exposure lamp 8 and the pre-discharge charger 2 and further corona-charged by the negative charger 3. The electrostatic latent image formed on the drum 1 is developed by the developing roller of the next developing device 7 and visualized as a toner image, and this toner image is copied onto copy paper. After copying, the drum 1 continues to rotate and is cleaned by the cleaning roller and elastic blade of the cleaning device 6 in preparation for the next image formation.

The copy paper stored in the upper cassette 12 or the lower cassette 13 is transported into the machine by paper feed rollers 10 and 11, and the registration roller 14 temporarily stops the copy paper being fed in the direction of the drum 1 so that the leading edge of the copy paper and When the leading edge of the latent image coincides with each other, the copy paper is sent out in the direction of the drum 1 again. Next, while the copy paper passes between the copy charger 5 and the drum 1, the toner image on the drum 1 is copied onto the copy paper. After copying is completed, the copy paper is separated from the drum 1 and guided by a conveyor belt 15 to a fixing roller 16, where it is pressurized and heated to fix the copy image. Next, the discharge roller 17
The copy paper is discharged onto the tray 18.

Next, the detection operation of the document position, document size, and document density will be explained with reference to the drawings.

After the main switch is turned on, the optical system drive motor 39 is driven to correct variations in characteristics of the light receiving element group 71 constituting the reflection density detector 35 and ripples of the light source, and the position sensor 30 indicating the position of the standard white plate 22 is moved. The moving optical system unit 24 is moved until the position detection piece 28 attached to the outside of the optical system unit 24 is detected. Next, when the irradiation lamp 25 irradiates the standard white plate 22 that provides a uniform reflection density, the reflected light is transmitted to the first scanning mirror 26.
．． Second scanning mirror 27. The document is fed into a reflection density detector 35 via a document detection lens 34. This reflection density is stored in the RAM 56 as a density correction value. Thereafter, the optical system drive motor 39 is driven to move the moving optical system unit 24 until the position sensor 31 indicating the position of the leading edge of the image area detects the position detection piece 28. Next, the original platen glass 19 on which the original 2o was placed with the original pressing plate 21 closed.
The upper image area is irradiated with the irradiation lamp 25 and measurement of the reflection density of the image area is started.

FIG. 5 is a diagram showing the correlation between the original 20 and the eraser 41, and (I) shows that the original 20 is connected to the original platen glass 19 and the original pressure plate 21.
(If) shows the state in which the original 20 is placed on the original table glass 19,
N) shows the relationship between the eraser 41 and the drum 1.

In (I[) of FIG. 5, A indicates the sub-scanning direction, B indicates the main scanning direction, and the shaded area indicates the image area. Note that l to n', -N, 1 to m', and -M indicate areas divided corresponding to the light receiving element group 71 of the reflection density detector 35.

Now, the reflection density detector 35 having a light receiving element group 71 finely divided in the main scanning direction B shown in (II) of FIG. 5 detects the reflection density of the entire image area as the moving optical system unit 24 moves. Then, that value is corrected using the density correction value and stored in the RAM 56 as an image density. That is,
The moving optical system unit 24 is moved in the sub-scanning direction A shown in FIG. Detect the reflection density of
The value is corrected using the density correction value and stored in the RAM 56 as an image density. Therefore, by performing this operation, the reflection density obtained by dividing the entire image area into fine meshes is detected as shown in FIG. The document size is determined from the image density obtained by correcting this reflection density using the density correction value.
Information on the image area within the document and the maximum and minimum reflection density of the document can be obtained. The MP 55 sends out each control signal based on this information.

Note that if the standard white board 23 is installed near the rear end of the image area as shown in FIG. After obtaining the density correction value, the position sensor 3
The movable optical system unit 24 is scanned in the sub-scanning direction A to the position 1, and the reflection density is measured by dividing the entire document copyable area into mesh shapes as described above.

Next, the operation of the control circuit of the present invention will be explained with reference to the control circuit diagram in FIG. 2 and the control signal timing chart in FIG. 6.

First, after turning on the main switch, in order to measure the reflection density of the standard white plate 22, the MP55 sends a motor control signal to drive the optical system drive motor 39 to the output ports Oz+ and O□2.
After moving the moving optical system unit 24 until the position sensor 30 detects the position detection piece 28 as described above, the standard white board 22 is irradiated with the irradiation lamp 25.

Then, a shift pulse signal SH shown in FIG. 6 is applied to the reflection density detector 35, and a clock signal φ1 obtained by frequency-dividing the clock signal CLOCK oscillated by the oscillator 51 by the frequency divider 52 and a clock signal which is its inverted signal Give φ2 and operate. The reflected light from the standard white plate 22 is transmitted to the light receiving element group 7.
Each element 1 to N of 1 detects the output voltage and sends the output voltage to the amplifier 5.
This output signal O8 is amplified by A/D converter 5.
4, the predetermined count number is processed as a dummy signal (a) as shown in FIG. 6 (hereinafter referred to as dummy processing). Here, dummy processing refers to processing for removing unnecessary signals (dummy signals) from among the signals of one scanning line output from the reflection density detector 35.

After that, the reflection density is read at the timing specified by the A/D in signal shown in Fig. 6, and when it is read 1 to N times as a detection signal (b), it is read in as much as the predetermined dummy signal (a). Count and perform dummy processing again. Note that the read reflection density data is RA
It is stored in the designated area of M56 as a degree correction value.

Next, after the MP 55 completes the dummy process, it turns the irradiation lamp 25 to 0FFL and waits for input of the copy start key of the input keys 58.

Next, when the input of the copy start key is applied to the MP55, the MP55 turns on the optical system drive motor 39 and starts irradiating the irradiation lamp 25, and moves the optical system until the position sensor 31 detects the position detection piece 28. After moving the unit 24, reading of the original image is started. While the moving optical system unit 24 moves in the sub-scanning direction A shown in FIG. 5, the MP55 starts an internal timer to output a shift pulse signal SH to the reflection density detector 35 at predetermined intervals (for example, 10 m5ec). , outputs a shift pulse signal SH every time the internal timer finishes counting. Then, the MP55 starts counting A/Din signals in order to perform dummy processing along with the output of the shift pulse signal SH, and when a predetermined number of A/Din signals have been counted, it is considered that the dummy processing is completed, and after that, the A/D in
At the reading timing specified by the signal, reflection density data 1 to N are sequentially input to each input port 1 of the MP55.
1 to i4, correction is performed using the density correction value stored in RAM 56, and data is stored in RAM 5 as image density data.
6 is stored in the designated area. And MP55 is 1-
When input of reflection densities up to number N is completed, the predetermined number of A/
The same dummy processing as described above is performed again until the counting of the Din signal is finished, and when the dummy processing is finished, the process waits until the counting of the internal timer is finished. When the internal timer finishes counting, the shift pulse signal SH is again applied to the reflection density detector 35, the internal timer is restarted, and the same process as described above is repeated.

This operation is repeated up to number M in the sub-scanning direction A, and the image density in the image area is obtained from the reflection density detected by the reflection density detector 35 as shown in FIG. , the original density is determined.

The drive driver 62 is driven in accordance with this document position, and a signal for controlling the eraser 41 is output to each output port 01 to 09 to prevent toner from adhering to the non-image area. In addition, the original density stored in the RAM 56 is compared with a predetermined reference black level value and reference white level value to determine the maximum density and minimum density, and the bias value of the developing device 7 is determined so as to obtain the optimum contrast. control.

Next, control of the eraser 41 based on the reflection density detected by the reflection density detector 35 will be explained with reference to FIGS. 1 and 2.

The eraser 41 is configured to emit light corresponding to each pixel of the light receiving element group 71 of the reflection density detector 35, and is
From the image density stored in M56, a set of pixels, that is, a non-image area, whose reflectance is lower than a predetermined reflectance is obtained. L of the eraser 41 corresponding to this non-image area
The ED emits light according to the copy magnification to prevent toner from adhering to this non-image area.

In addition, the reflectance of pixels on the boundary between the non-image area and the image area is lower than that of a blank original when the original pressure plate 21 is made of a mirror surface, etc., and when developing and copying is performed in this state, the copy paper Toner adheres to the outline of the image. To prevent this, the LED of the eraser 41 corresponding to the pixel on the boundary between the non-image area and the image area is caused to emit light to prevent toner from adhering (edge processing).

Furthermore, a switch 29 provided near the original support table is turned on.
When a signal indicating a non-contact state between the NL original pressure plate 21 and the original platen glass 19 is input to the input port i12 of the MP 55, the MP 55 determines that the original 2o is a book. Therefore, after the reflection density detector 35 detects a document edge, until it detects a white standard higher than a predetermined reflectance, it is determined that the edge is a collection of book edges, and the eraser 41 detects this edge. A control signal is output to each output port 01 to 09 so that the LED corresponding to the set of edges emits light, and the drive driver 62 receives this output and drives, and the LED corresponding to the above-mentioned set of edges emits light. This prevents toner from adhering to the edges where the edges gather.

Further, when the original 20 is a book, a halftone having a reflectance lower than a predetermined reflectance exists in the reflection density detected by the reflection density detector 35 in the center of the original, and the main scanning As a result, the set of halftones is manuscript 2.
If the halftone exists in the edge direction of 0, the MP55 determines that this halftone is due to the fold of the book, and switches each output port 01 to 09 so that the LED corresponding to the position of this halftone in the eraser 41 emits light. A control signal is output to the drive driver 62 which receives this output and drives.
The LED corresponding to the above halftone position emits light. This prevents toner from adhering to the halftone position.

Next, edge control in the image area will be explained.

Note that, hereinafter, the original pressure plate 21 is assumed to have a mirror surface.

As mentioned above, the reflection density of the image area is detected by the reflection density detector 3.
When each pixel is detected by the light receiving element group 71 of 5,
After the set of pixels showing low reflectance, a set of pixels showing high reflectance (original portion) is obtained. The document position and document size can be obtained from the boundary between the set of pixels exhibiting low reflectance and the set of pixels exhibiting high reflectance. In particular, when it is necessary to copy the original 20 on this boundary, when copying is performed using the original size and original position stored in the RAM 56, the eraser 41 prevents toner from adhering to the original 20 on the boundary, including on the edge of the original. Therefore, it is determined whether edge processing is necessary based on the reflectance of the next pixel after the pixel on the boundary. In other words, if characters or the like are printed on the original in the pixel next to the pixel on the boundary, the reflectance will be low. Using this as a criterion, if the reflectance is lower than a predetermined reflectance, the MP55 determines that it is necessary to attach toner to the pixels on the edge of the document, and ) to control the reduction and copying.
Furthermore, if the reflectance of the pixel next to the pixel on the boundary is higher than a predetermined reflectance, control is performed to copy at the same size.

Therefore, if there are characters or the like near the boundary, they are reduced, so the characters near the boundary are not affected by image erasure (edge processing) by the LED, that is, the eraser 41.

Next, the control operation for automatic magnification change will be explained.

As mentioned above, the reflection density of the image area is detected by the reflection density detector 3.
When each pixel is detected by the light receiving element group 71 of 5,
After a set of pixels exhibiting high reflectance, a set of pixels exhibiting low reflectance is obtained. An image area is obtained from the boundary between the set of pixels exhibiting high reflectance and the set of pixels exhibiting low reflectance. This image area and cassette size oysters-571~
573, and compare the size of the copy paper stored in the upper cassette 12 or lower cassette 13 with the copy paper size of the copy paper obtained by 573, and if the same size copy paper is stored in the upper cassette 12 or lower cassette 13, copy at the same size. conduct. on the other hand,
If the above image area and the above copy paper size are different,
The most appropriate reduction or enlargement is selected and the copy is made at a predetermined magnification so that the entire image area is copied onto the copy paper.

Next, the operation of automatic density control will be explained with reference to FIGS. 1, 2, and 7.

FIG. 7 is a characteristic waveform diagram showing the density characteristics, and the first quadrant shows the relationship between the exposure amount (E) and the potential (V) of the drum 1,
The second quadrant shows the potential of the drum 1 (v) and the density of the copied image (DC
), and the third quadrant is the density of the copied image (DC).
The fourth quadrant shows the relationship between the original density (DO) obtained from the reflection density detected by the reflection density detector 35, and the fourth quadrant shows the relationship between the original density (D O)
The relationship between Do) and exposure amount (E) is shown.

As mentioned above, the reflection density of the image area is detected by the reflection density detector 3.
When each pixel is detected by the light receiving element group 71 of 5,
After a collection of pixels exhibiting high reflectance, pixels exhibiting low reflectance are obtained. Among these images, the one with the highest reflectance (ground color, reference white level) among the images showing low reflectance has a density of 0.
．． 07, and when the minimum reflectance is at a density of 0.5, an input voltage of 65V is applied to the irradiation lamp 25, and the potential of the drum 1 is determined by the E-V characteristic shown in the first quadrant. 1ooO of the development characteristics determined and shown in the second quadrant
A copy image with a density determined by a Hz, 1ooovp-p curve is obtained.In the above example, an original density of 0.07 is developed to a copy density of 0.07, and an original density of 0.5 is developed to a copy density of 0.07. Developed to a copy density of 0.5. In other words, the original density and the copy density are the same. On the other hand, if the difference between the maximum and minimum document densities is smaller than a predetermined value, the copy density is changed as described below.

For example, if the minimum value of the original density before the change was 0.2 and the maximum value was 0.5, it is assumed that the EV characteristic in the first quadrant does not change, and the original density of 0.2 is copied to 0. When changing to .07, the original density is reduced to 0.5 by controlling the input voltage of the irradiation lamp 25 shown in the fourth quadrant to be set to 8 ov. Further, the development characteristics in the second quadrant are controlled to be set to 1600 Hz and 1800 Vp-p. With this control, if the difference between the maximum and minimum document density is smaller than a predetermined value, that is, the contrast is artificially added to the document 2o whose contrast is not clear, and the appropriate density is set. Obtain a clear copy image.

Next, the registration roller 14 and eraser 4
1 will be explained with reference to FIGS. 1 and 2.

There is a predetermined document reference position on the document platen glass 19, and when it is determined from the reflection density detected by the reflection density detector 35 that the leading edge of the document deviates from this document reference position, as described above. is the LED of the eraser 41 corresponding to the pixel of the light receiving element group 71 that detected high reflectance.
In addition to emitting light to prevent toner adhesion, the drive timing of the registration rollers 14 is delayed and the registration (
By aligning the leading edge of the copy paper and the leading edge of the image, deviation of the leading edge of the original from the original reference position can be corrected and a proper image can be obtained. In addition, if it is determined from the reflection density detected by the reflection density detector 35 as described above that the leading edge of the original is set at an angle of more than a predetermined parallelism with respect to the original reference position, Stop copying and copy original 20
Displays a request for resetting.

Next, control by the MP 55 will be explained with reference to flowcharts shown in FIGS. 8(a), 8(b), and 8(c). Note that (1) to (47) represent each step.

When the power of the image processing device is turned on, it starts warming up and determines whether it is the measurement position of the standard white board 221)
, the optical system drive motor 39 is rotated in the reverse direction until the position sensor 30 detects the position detection piece 28 (2), step (1)
), if the standard white plate 22 is at the measurement position, the optical system drive motor 39 is set to oFFL (3), and the irradiation lamp 25 is set to O.
Do N (4). Next, it waits for the input of the shift pulse signal SH, and when the shift pulse signal SH is input, the A/D
The in signal is counted and dummy processing is performed (5), and then the reflection density of the standard white board 22 is detected and the input of the shift pulse signal SH is waited again (6).

After inputting the shift pulse signal SH, turn the irradiation lamp 25 to 0F.
FL (?), wait for input of copy start key (8
). From this point on, the process moves to the flow shown in FIG. 8(b), and when there is a copy start input, it is determined whether the stop position layer of the moving optical system unit 24 is at the position of the standard white board 22 (9), No.
If so, the optical system drive motor 39 is rotated in the reverse direction (10). If YES in step (8), the optical system drive motor 39 is rotated forward (11), the moving optical system unit 24 is moved in the sub-scanning direction, and the irradiation lamp 25 is turned on (12). Next, it is determined by the position sensor 31 whether the moving optical system unit 24 has reached the leading edge of the image area (13), and if no, the system waits until it reaches the leading edge of the image area. Step (
If YES in step 13), initial values regarding the image area and original area are set (step 14), and a reference black level and reference white level of reflection density are further set (step 15). After setting, wait for input of shift pulse signal SH and input A/Din.
The signals are counted (16), and after the counting is completed, the reflection density of the image area in the sub-scanning direction is detected and stored for each light receiving element of the light receiving element group 71 (17). Next, it is determined whether the measurement of the reflection density of one image area has been completed (18). If the determination in step (18) is No, the process returns to step (16) to continue detecting the reflection density of the image area. Also,
If YES, dummy processing similar to step (16) is performed and the irradiation lamp 25 is turned off (18). Next, step (17) is performed using the density correction value stored in step (8).
The reflection density stored in step 2 is corrected (20). Next, the reflection density corrected in step (20) is compared with the reference black level reflection density set in step (15) for each light receiving element (21), and the maximum reflection density is determined and stored in the RAM 56 (22). ). Next, the reflection density stored in step (17) is similarly compared with the reference white level reflection density set in step (15) for each light receiving element (23).
The minimum reflection density is determined and stored in the RAM 56 (24). After this, the process moves to the flow shown in FIG. 8(C), and then the reflectance data stored in step (18) is adjusted for each pixel. 26) to form a set and detect the original size and the image area within the original size, and eraser 4 corresponding to the non-image area.
Set the light emission of LED 1 (27). Next, check whether the reflectance of the pixel next to the pixel on the outline of the document size detected in step (26) is lower than a predetermined reflectance28), and if NO, set the copy magnification to reduction. 29) Then, the light emission of the LED of the eraser 41 is set according to this magnification (30). Next, step (22) calculates the density difference between the maximum density and minimum density in the reflection density data stored in step (24).
), determine whether the difference is smaller than a predetermined concentration difference (3
2). If this judgment is YES, then the distance from the document size outline to the leading edge of the image in the document size is calculated and it is determined whether the distance is smaller than a predetermined distance difference33), and if YES, the cassette size is equal to the document size. Check 34), and if YES, set the bias value of the developing device 7 or the light intensity of the irradiation lamp 25 according to the reflection density stored in step (18) 38), and start copying (3).
8). On the other hand, if NO in steps (33) and (34), change the copy magnification35) and set the light emission of the LED of the eraser 41 according to this copy magnification36).
, proceed to step (38). Also, in step (32)
If O, set the copy density to 3? ), the light intensity of the irradiation lamp 25 or the bias value of the developing device 7 is set according to this copy density (38).

On the other hand, if YES in step (28), the copy magnification is set to equal magnification (40). Then switch 29 is turned on
Please check the status 41), it is OFF instead of ON.
Then, L of the eraser 41 corresponding to the contour point of the document size
Set the ED light emission (44), and jump to step (31). If YES, determine whether there is a set of pixels exhibiting high reflectance from the document size contour point to the edge of the image area in the document size (42). ), if YES, it is further determined whether there is a set of pixels showing high reflectance in the main scanning direction within the document size (43); if YES in this judgment, the Set the light emission of the eraser 41 corresponding to the high reflectance area (47) and jump to step (31). Also, N at step (42).

In this case, a document setting failure is displayed (45). moreover,
If No in step (43), the eraser 41 is set to emit light corresponding to pixels from the document size outline to the tip of the pixel area in the document size (46), and the process jumps to step (31).

〔Effect of the invention〕

As explained above, the present invention includes a document information detection means for detecting the density and document size of the document by receiving reflected light from the document, and a non-image area of the photoreceptor detected by the document information detection means. Since an eraser means for irradiating light is provided, the condition of the original (original size, original density, original position, 1 image area) can be detected by the same detection means, the configuration of the apparatus can be made compact, and clear copied images can be obtained. It will be done. Furthermore, since the image is formed according to the detected image area, it has the advantage that a precise image can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of an image processing device showing an embodiment of the present invention, FIG. 2 is a control circuit diagram, FIG. 3 is a front view of a reflection density sensing element showing an embodiment of the invention, and FIG. The figure is a density characteristic waveform diagram showing the relationship between reflected density and output voltage, Figure 5 is a scan schematic diagram showing division in the scanning direction, Figure 6 is a timing chart of each control signal, and Figure 7 is a density characteristic diagram. The characteristic waveform diagrams in FIGS. 8(a)', (b), and (c) are flowcharts showing an example of control. In the figure, 1 is a drum, 2 is a pre-static charger, 3 is a primary charger, 4 is a charger, 5 is a copying charger, 6 is a cleaning device, 7 is a developer, 8 is a pre-exposure lamp, and 9 is a front surface Exposure lamp, 10.11 is paper feed cassette, 12 is upper cassette, 1
3 is a lower cassette, 14 is a registration roller, 15 is a transport belt, 16 is a fixing roller, 17 is an ejection roller, 18 is a tray, 19 is an original table glass, 2o is an original, 21 is an original pressure plate, 22.23 is a standard white board , 24 is a moving optical system unit, 25 is an irradiation lamp, 26 is a first scanning mirror, 27 is a second scanning mirror, 28 is a position detection piece, 29 is a switch,
30, 31. 32 is a position sensor, 33 is a slit, 34
36 is a projection lens, 35 is a reflection density detector, 37 is a third scanning mirror, 38 is a fourth scanning mirror, 39 is an optical system drive motor, 40 is a main motor, 4
1 is an eraser, 51 is an oscillator, 52 is a frequency divider, 53.6
0 is an amplifier, 54 is an A/D converter, 55 is a microprocessor, 56 is a RAM, 57□ to 573 are cassette size input keys, 158 is an input key, 159 is a D/A converter, 6
1 is the lamp regulator, 62.63 is the drive dry/to, 64 work. 642 is an AND circuit, 65+, 652 . 66 is an inverter, 67 is a clock signal, and 71 is a group of light receiving elements. Figure 3: Tsuzuri Ir4 - Exhibition Figure 5

Claims (1)

[Claims] An image processing device that irradiates a document placed on a document support table with an irradiation lamp and forms an image of the reflected light on the surface of a photoreceptor, receives the reflected light from the document and determines the density and document size of the document. a document information detecting means for detecting, an eraser means for irradiating light only to the non-image area of the photoreceptor detected by the document information detecting means, and a copy density according to the document density detected by the document information detecting means. An image processing apparatus comprising a copy density setting means for setting a copy density.