JPS62257142A - Image correcting device for flotation of document on image forming device - Google Patents

Abstract

PURPOSE:To correct the flotation of a book document in image formation by converting the output of a flotation quantity detecting and supporting means into a digital value, comparing its output with a reference signal and outputting their difference, and setting the quantity of movement of a lens. CONSTITUTION:Arithmetic processing for extracting the quantity of flotation of the document in the form of a voltage is carried out and the quantity is converted into the digital value by an A/D converter, whose output is compared by a differential means with the digital output value of the A/D converter as a measured position based upon a signal detected immediately before to calculate the difference. Then, the difference of the differential means which is their difference is set in a counter by a counter number converter. The output of the differential means is decided by a plus/minus judging device and a lens motor 17 moves the lens 9 toward, for example, the document 1 when the difference is plus of a photosensitive body 11 when minus. A pulse signal generated by an encoder 29 is counted by the counter, and the motor 17 is stopped when the counter reaches the set counter number.

Description

DETAILED DESCRIPTION OF THE INVENTION [Blood blister] The present invention relates to an apparatus for correcting image blur caused by lifting of a document in an image forming apparatus.

Conventionally, in night-time image forming apparatuses, such as copying machines, it is common practice to set an original at a reference position on a contact glass serving as an original table, and to press the original with a pressure plate to perform copying operations such as exposure. .

Manuscripts include thin sheet-like manuscripts, thick books, magazines,
There are book originals such as bound materials.Sheet-like originals can be exposed to light by being placed in close contact with a contact glass using a pressure plate to block external light, but with book originals, the specified page to be copied is opened and exposed to the contact glass. It is held down by the placing pressure plate in the same way, but since there is a binding part in the center, that part rises above the contact glass that serves as the document table. For this reason, characters and the like in the raised portions are exposed to light while being away from the contact glass, resulting in the image being blurred. In more extreme cases, black streaks may appear if the surface is too high.

The thicker and newer the book manuscript is, the more it will bleed, and if you copy it as is, the image will be blurred and the black lines will become wider, resulting in an unsightly copy. In order to avoid such a situation, the raised part is pressed by hand from one side of the document pressure plate to reduce the raised part. Although this method reduces the width of the blur and black screws, it cannot be completely eliminated, and the binding of book manuscripts becomes more prone to tearing, which quickly damages valuable materials.

Partial erasing is performed on the image surface of the photoreceptor in the area corresponding to the raised ridges. Although this method can erase black streaks, depending on the degree of raised ridges, it may not be possible to erase necessary information such as literature. will also be deleted.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned conventional problems and to provide an apparatus capable of correcting the raised appearance of a book document during image formation.

1. In order to achieve the above object, the present invention includes a document lifting amount detecting means, a moving means for moving either the lens or the mirror of the optical device along the optical axis, and a digital converter for converting the output of the detecting means. A D/A converter that converts the output into a value, a differential means that compares the output of the D/A converter with a reference signal and outputs a difference, and moves the lens based on the output signal of the differential means.
The present invention is characterized in that it includes a movement amount setting means for setting the amount of movement, and a motor drive device for driving and controlling the movement means based on a signal from the movement amount setting means.

The structure and operation of the present invention will be explained in detail based on the embodiment shown in the drawings.

In FIG. 1, a copying apparatus, which is an example of an image forming apparatus, has a contact glass 3 having an alignment reference position 2 of an original fgli as an original table.

A scanner 4 that performs exposure scanning on a document 1 placed on a document table has a lamp 5 and a first lamp that reflects light reflected from the document.
It has a mirror 6. The image light reflected by the first mirror 6 is incident on the lens 9 by the second mirror 7 and the third mirror 8, and is imaged on the photoreceptor 11 via the fourth mirror 10.

Scanner 4 has pulleys 12 and 13 and drive pulley 1
The scanner 4 scans the document surface for exposure at a predetermined speed from the reference position 2 side, and then reverses and recovers the original surface by scanning the document surface at a predetermined speed from the reference position 2 side. and stops near the reference position.

The lens 9 is supported movably in the optical axis direction, is connected to a lens motor 17, and is moved in the optical axis direction by driving of the lens motor 17.

A structure may also be adopted in which a mirror block (not shown) on which the second mirror 7 and third mirror 8 are mounted instead of the lens 9 is connected to a motor, and the mirror block is moved in the optical axis direction by the drive of the motor. can.

Furthermore, in the case of an apparatus having a magnification conversion mechanism, a magnification setting motor that drives the lens and mirror block can be used, and switching can be made to drive only the lens or only the mirror block.

To simplify the explanation, an example in which a lens is moved will be described below, but it goes without saying that a similar configuration can be used in an example in which a mirror is moved.

A start signal as a control signal from the control device drives the lens motor 17 via the lens motor shaft drive device 18, and the lens 9 starts to move by a predetermined amount.

A light source 19 and a light sensor 20 are arranged near the lens 9 and slightly offset from the main optical path, as shown in FIG. A condensing lens 21 is placed just in front of the light source 19, for example an LED, and a third mirror 8. The configuration is such that a portion of the third document 1 is irradiated via the second mirror 7 and the first mirror 6. In this case, the optical sensor 19 is positioned and arranged so as to receive the reflected light from the original 1 at a position after passing through the mirror 6.7.8.

Immediately in front of the optical sensor 20, an imaging lens 22 is arranged so that the reflected light from the original is imaged on the light receiving surface of the optical sensor 20.

With this configuration, when the original 1 is in close contact with the contact glass 3, if the reference position is set at the position where the optical sensor 20 receives the light reflected from the original 1 by the light from the light source 19, the original Since there is a gap between the contact glass 3 and the document surface in the part where 1 is raised and lowered, the position of incidence of the illumination light from the light RI 9 on the optical sensor 20 changes. By detecting the deviation of this incident position from the reference position, the extent to which the original 1 is lifted can be determined.

When the copying magnification of the copying machine is 1x, if the lens 9 is located in the center of the optical path from the original g11 to the photoreceptor 11, a clear image without blur is formed on the photoreceptor 11. . Therefore, when the lifting of the original 1 occurs and the lifting amount is detected as described above, 1/1 of the detected lifting amount is detected.
By moving the lens 9 toward the original 1 along the optical path by a length equal to 2, the lens can be positioned in the center of the optical path between the original 1 and the photoreceptor 11, thereby preventing image blurring. can do. In other words, if the lens 9 is moved along the optical path according to the amount of lift of the original 1, a clear image without blur can always be obtained.

When the copying magnification is other than the same magnification, it is preferable to increase or decrease the amount of movement of the lens 9 depending on the magnification compared to the case of the same magnification.

As the optical sensor 20 described above, a semiconductor device detection element (PSD) can be used as an example.

The case where the semiconductor device detection element is used as the optical sensor 20 will be described below.

As shown in FIG. 3, the semiconductor device detection element has a high-resistance Si substrate 23 with nFi 24 on one side and a P-type paper antilayer 25 on the other side.
It is formed as a uniform resistive layer, and exhibits a photoelectric effect when exposed to incident light. Input electrode 26 is on one layer, P-type paper anti-layer 2
5 has a first output electrode 27 and a second output electrode 2 at both ends thereof.
8 is provided.

When the incident light enters the point R of the P-type paper anti-layer 25, a photocurrent 1. generated due to the photoelectric effect is generated. are the output current ■1 at the first output electrode 27 and the output current I2 at the second output current 28.
It is divided into In this case, the output current 11. I2 is extracted in inverse proportion to the resistance value from the point of incidence to each output electrode.

The length of the semiconductor device detection element, that is, both output electrodes 25.
If the total surface resistance of the length C1 between 26 and 26 is R5, the distance from the center of the semiconductor device detection element to the point of incidence R is X, and the sheet resistance from the center to the point of incidence is Rx, then if the resistance distribution is uniform, Rlccz This is because it is.

In FIG. 4, parallel light from the light source 19 passing through the condensing lens 20 is a distance NIL from the position 0 of the condensing lens 21.
The light-receiving surface of the semiconductor device detection element 20 partially illuminates the document surface that is separated by the distance β, and the reflected light passes through the imaging lens 22 located at a point O′, which is a distance β apart from the condensing lens 21, and enters the light-receiving surface of the semiconductor device detection element 20. If the distance from the imaging lens 22 is h, then the amount of deviation X of the incident point R of the semiconductor device detection element 20 from the center is as follows.

Assuming that the document surface that is a distance away from the condensing lens 21 is a reference surface in contact with the contact glass, and considering the case where the document is lifted by a distance ΔL from this reference surface, the reflected light from the document is reflected by the imaging lens 22. The light passes through the semiconductor device detection element 20 and enters the point R' of the semiconductor device detection element 20, and is shifted from the point R by a distance ΔX.

Therefore, in this case, the current ratio a is is obtained.

From this, the lifting distance ΔL of the original can be determined by knowing the ratio a of each current of the semiconductor device detection element.

In FIG. 5, the quantity output currents 1 and I2 of the semiconductor device detection element are input to a signal calculation device, and calculation processing is performed to extract the amount of document lifting in the form of a voltage. The output of the signal processing device is converted into a digital quantity by an A/D converter, and both output currents are taken out as an output voltage proportional to the current ratio.

For example, as shown in FIG. 6, the signal calculation process by the signal calculation device logarithmically converts the output current 11 from the first output electrode and the output current I2 from the second output electrode using a logarithmic conversion device, and converts the output U1. This can be done by calculating the difference between U2 in a differential circuit.

The output from the A/D converter is compared with the digital output value from the A/D converter as the measurement position based on the signal detected immediately before by the differential means, and the difference is calculated. The difference value as an output is converted into a count number proportional to the difference value in a count number converter, and that value is set in a counter.

The output value of the differential means is set in the counter based on the change from the previous measured value. That is, it is the amount of change from the amount of lifting of the document immediately before, and the lens is moved by a distance corresponding to this amount.

In other words, the count number of the counter indicates the amount of lifting of the document, that is, the amount of movement of the lens necessary to correct the blurring of the image. The encoder 29 is attached to the lens motor 17.
(Fig. 1) are connected, and if the relationship between the output pulse number of the encoder 29 and the count number of the force counter is set in advance according to the relationship between the amount of lift and the amount of lens movement to correct it, it is possible to The lens motor 17 is activated by the count signal sent to the motor drive device 18.

The output of the differential device is determined by a positive/negative determining device, and if the output is positive, the lens motor 17 is driven in a direction that moves the lens 9 toward the document 1, for example, and if it is negative, the lens 9 is driven toward the photoreceptor 11. .

The lens, which is moved by the rotation of the activated lens motor 17, uses the counter to count pulse signals generated by the encoder 29 connected to the lens motor, and when the counted number reaches the set count number, the pulse signal is output from the counter. A stop signal is sent to the motor drive device 18 to stop the motor 17.

In another embodiment, the scanner 4
Perform a preliminary scan. The scanner 4 starts preliminary scanning from the reference position 2 (FIGS. 1 and 8).

The scanner 4 is driven by a drive motor 16, and its [
! A pulse signal output from an encoder 30 connected to the motor 16 is sent to a counter (not shown). The moving distance of the scanner 4 is detected as the distance from the reference position 2 by converting the pulse signal of the encoder 3o into the document length using a calculation device (not shown). A signal indicating the detected moving distance is converted into document length at predetermined intervals and temporarily stored in a storage device (not shown).

When the preliminary scan of the scanner 4 is started, the CPU (not shown)
The scanning reference signal is sent to the lighting device shown in FIG. 7, the storage device, and the arithmetic unit 2 (not shown) that calculates the moving length. In this case, the light source 19 connected to the lighting device is turned on at predetermined intervals by the scanning reference signal, irradiating the document surface, and reflected light enters the semiconductor device detection element 20.

A count number conversion device that calculates and converts the light incident on the semiconductor device detection element 20 and outputs a count number corresponding to the difference from the previous amount of uplift, and a positive/negative judgment that determines whether the difference from the amount of uplift immediately before is positive or negative. The circuit configuration up to the device is the same as that shown in FIG. 5, so a description thereof will be omitted.

The count number based on the output signal of the count number conversion device and the information on genuine coins that is the output signal of the sign determining device are temporarily stored in the storage device.

When the document 1 on the contact glass 3 is lifted up as shown in FIG. Since there is no uplift, the difference between the count number during that time and the count number immediately before it is 0. Travel distance L
OΦ measurement When the constant interval source 18 is turned on after the measurement, the scanner 4 has advanced to the position L=LL, and the lifting amount of the original l at this position is ΔL1. Therefore, optical sensor-2
The point of incidence of the incident light on 0 is shifted. The count number corresponding to this deviation amount, that is, the floating amount Δ1,1 is the immediately preceding (ΔL=
Information regarding the difference between the count number (at the 0 position) and its positive/negative difference (pressure in this case) is stored in the storage device at the scanning position L=
It is temporarily stored together with information regarding L1.

Similarly, at the time of the next lighting, the difference ΔL from the previous floating and rising information ΔL1 with respect to the floating amount ΔL2 at L=L2
Information of 2-ΔL1 is stored in the storage device, and at the time of the next lighting, information regarding the floating amount Δl12-ΔL3 at L=L3 is stored in the storage device.

The floating amount ΔL−ΔL when the scanner 4 further advances to the position L=L4 and the light source 19 is lit by the lighting device
4 is the difference ΔL4- from the amount of uplift at the previous L=L3
The signal of ΔL3 is stored in the storage device.

At this time, the counter number is 1ΔL4-ΔII3l, and the output signal from the positive/negative determining device becomes "negative" information. In this way, the amount of uplift is sequentially detected. When the preliminary scanning is completed in this way, the copying operation is started.

During the copying operation, up to L=Lo, the lifting amount ΔL=0, so the lens motor 17 does not operate and the lens 9 is held at the normal reference position.

When the scanner 4 comes to the position L−L, the information stored during the preliminary scan is called up, and the lifting amount ΔL=ΔL1
For example, in the case of the same size, ΔL1/
The lens 9 is moved by 2 and then stops. Furthermore, L=L2
At the position, the lens is moved in the direction closer to the original 1 by a count of Δ1,2-ΔL1 to correct the amount of floating trim.

Thereafter, the lens 9 is similarly moved to each position by the distance necessary to correct the lifting amount at that position in C). L=
At L5, the positive/negative judgment is "negative", so the lens 9 is moved in the direction closer to the photoreceptor 11.

In this way, the copying operation is performed while correcting the position of the lens according to the amount of floating.

The shorter the predetermined interval during preliminary scanning, that is, the lighting interval of the light source 19, the more accurately the lens position can be corrected in proportion to the amount of floating, but if it is too short, the operation may be delayed or the memory of the storage device may be damaged. It becomes necessary to increase the capacity. If the predetermined interval is too long, even after correction, some areas will remain where the image will be blurred. Therefore, it is necessary to set an appropriate interval.

This predetermined interval is set short, and when the count number that is the output of the count conversion device exceeds the predetermined count number,
Necessary information such as count number, positive/negative information, scanner movement distance, etc. may be set by being stored in the storage device.

As the predetermined count number, it is convenient to select, for example, a count number corresponding to the amount of floating by a distance equal to the depth of focus of the lens.

In this way, if the amount of floating is less than the depth of focus of the lens, blurring of the image will not occur, but when the amount of floating is greater than the depth of focus and blurring occurs,
The lens can be moved to be included within the depth of focus range to avoid blurring, and a blur-free image can always be obtained.

A limit is set on the amount of lens movement correction corresponding to the amount of lift.
There is also a method in which the upper limit of the correction amount is set for an extremely large floating amount. This can prevent the mechanism from becoming complicated due to an increase in the amount of movement of the lens.

FIG. 9 shows a change in the lens movement amount with respect to a change in the lifting amount ΔL of the original, and the lens is moved in stages. As an example of this case, the detected amount of uplift can be taken as the depth of focus f.

As the optical sensor, an image sensor (CCD) 20' as shown in FIG. 10 can also be used.

While the semiconductor detection element detects a change in the position of the incident light as a change in the output current ratio, an image sensor only needs to detect a change in the incident pixel number of the incident light.

If the pixel pitch of the image sensor is p, the pixel number of the image sensor corresponding to X in Fig. 4 is x / p.
The positional change ΔX of the incident light changes by the number of pixels corresponding to Δx/p.

If the document is raised, in the case of an image sensor, one light source illumination will strike the position of the pixel number corresponding to Δx/p, and N charges will be multiplied only in that pixel. - A pixel number of 6i can be recognized in one scan by the drive device, and if the output is A/D converted, the digital signal is processed in the same manner as in the case of Fig. 7, and the above Similarly, the position of the lens can be corrected to prevent blurring.

When using an image sensor, the scanning time can be set shorter than the predetermined interval in the example above.

(2) According to the present invention, since the position of the lens is moved according to the amount of lifting of the original, it is possible to prevent blurred images from occurring on the photoreceptor, and it has become possible to change copies that are always easy to see.

According to the present invention, since the light source and the optical sensor for detecting floating are arranged at a position away from the main optical path, the floating can be detected without being a hindrance during copying.

Since the light source for detecting the lifting amount is blinked at predetermined intervals, lifting amount information can be detected at all times.

Prior to exposure scanning for the copying operation, information on the amount of lift on the original is scanned and detected, converted into step-like information, and stored. Therefore, during copying, the lens is scanned and detected in steps based on the information from the storage device. Since the lens is moved and stopped reliably, the lens position can be reliably corrected, and therefore, the correction to eliminate image blur can be reliably performed.

Since the lift amount is detected as a digital value representing the difference from the previous lift amount measurement value, the amount of lens movement only needs to be the change from the previous position, so the amount of movement is small and there is no delay. It can be corrected without fail.

Since the amount of lift is stored together with the positive/negative judgment information, the movement of the lens to correct lift can be made to reliably respond to both increases and decreases of lift, and can be done with the minimum amount of movement. .

By making the amount of movement of the lens step-like and setting the step interval in relation to the depth of focus of the lens, it is possible to reduce the movement of the lens and reliably correct blur. Furthermore, the lens moving mechanism that sets a limit on the amount of lens movement can be simplified.

[BRIEF DESCRIPTION OF THE DRAWINGS] FIG. 1 is a schematic diagram of a copying machine having a correction device according to the present invention, FIG. 2 is a diagram of a document lifting amount detection means, and FIG.
The figure is an explanatory diagram of an example of an optical sensor, Figure 4 is an explanatory diagram showing the principle of detecting a change in the amount of lift, Figure 5 is a circuit diagram of an information processing device that detects the amount of lift, and Figure 6 is a diagram illustrating the principle of detecting changes in the amount of lift. Fig. 7 is an explanatory diagram of the signal calculation device, the seventh slit is a diagram of a modified example of the information processing circuit diagram, Fig. 8 is an explanatory diagram of preliminary scanning of the floating amount, and Fig. 9 is an illustration of the lens movement amount and the floating amount. FIG. 1θ, which is a diagram showing the relationship with change, is a diagram corresponding to FIG. 7 of another modification. 1... Original 3... Original table 4... Scanner 5... Lamp 6.7.8. 10... Mirror 9... Lens 11... Photoreceptor 19... Light source (document lifting amount detection means) 20... Optical sensor (document lifting amount detection means) Fig. 1 Fig. 2 Figure 3 Figure 4 Procedural amendment November 10, 1985 Commissioner of the Patent Office Black 1) Akio Yu 1, Indication of the case 1986 Patent Application No. 99374 2, Name of the invention Embossed manuscript of image forming device Relationship between the image correction device 3 and the person making the correction Patent applicant name (674) Ricoh Co., Ltd. 4, agent address Kaji Kogyo Building, 2-32-4 Nishi-Shinbashi, Minato-ku, Tokyo
Address: 105 (433) 45646, Scope of Claims, Detailed Description of the Invention, Brief Explanation of Drawings, and Drawing 7 of the Specification Subject to Amendment, Contents of Amendment (1) As shown in the attached sheet (Subject to Amendment) There are no changes to the contents other than those stated in.)
1. Title of the invention: Image correction device for image forming apparatus due to raised original 2; Claims: Exposure scans the original on the original platen, and forms the original image on the photoreceptor by an optical device having a group of mirrors, lenses, etc. In the image forming apparatus, the document floating position detecting means, the moving means for moving either the lens or the mirror of the optical device on the optical axis, and the D/A converter for converting the output of the detecting means into a digital value. a differential means for comparing the output of the D/A converter with a reference signal and outputting a difference; and a movement amount setting means for setting the amount of movement of the lens based on the output signal of the differential means. An image correction device for an image forming apparatus based on lifting of a document, characterized in that the image forming apparatus further comprises a motor drive device that drives and controls the moving means based on a signal from the moving amount setting means. 3. Detailed description of the invention Narrowing section The present invention is aimed at reducing the amount of paper that is caused by the lifting of a document in an image forming apparatus.
Jf J+length groan τsu 2 revenge tψ4su 1ノ, small image 21 rice thorn distortion In an image forming device, for example, a copying machine, the original is set at a reference position on the contact glass that serves as the original platen, and the original is It is common practice to hold down a document and perform copying operations such as exposure. Manuscripts include thin sheet-like manuscripts, thick language manuscripts, magazines,
There are book manuscripts such as bound materials. Sheet-like manuscripts can be exposed to light by being placed in close contact with a contact glass by pressing to block external light, but with book manuscripts, the specified page to be copied is opened and exposed on the contact glass. It is the same as when placed on a paper and held down by pressure, but since there is a binding part in the center, that part rises above the contact glass that serves as the document table. For this reason, characters and the like in the raised portions are exposed to light while being away from the contact glass, resulting in blurred images. In even more extreme cases, black streaks may appear if the surface is raised. The thicker or newer the book manuscript is, the more raised it is, and if it is copied as is, the image will be blurred and the black lines will become wider, resulting in an unsightly copy. In order to avoid such a situation, the raised portion is usually pressed down by hand from above the document pressure plate to reduce the raised portion. Although this method reduces the width of the blur and black lines to some extent, it cannot completely eliminate them, and the binding of book manuscripts becomes more prone to tearing, which can quickly damage valuable materials. Partially erasing the part corresponding to the raised part on the image surface of the photoreceptor is performed, but although this method can erase black streaks, depending on the degree of raised part, even necessary information such as characters can be erased. It will be deleted. SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned conventional problems and to provide an apparatus capable of correcting the raised appearance of a book original during image formation. Natsui In order to achieve the above object, the present invention includes a document lifting amount detection support means, a moving means for moving either the lens or the mirror of the optical device on the optical axis, and a digital method for converting the output of the detecting means. A D/A converter that converts the output into a value, a differential means that compares and calculates the output of the acid D/A converter with a reference signal and outputs a difference, and an output signal of the differential means that determines the amount of movement of the lens. The present invention is characterized in that it includes a movement amount setting means for setting the amount of movement, and a motor drive device for driving and controlling the movement means based on a signal from the movement amount setting means. The structure and operation of the present invention will be explained in detail based on the embodiment shown in the drawings. In FIG. 1, a copying apparatus, which is an example of an image forming apparatus, has a contact glass 3 having an alignment reference position 2 for an original 1 as an original table. A scanner 4 that performs exposure scanning on a document 1 placed on a document table has a lamp 5 and a first lamp that reflects light reflected from the document.
It has a mirror 6. The image light reflected by the first mirror 6 is incident on the lens 9 by the second mirror 7 and the third mirror 8, and is imaged on the photoreceptor 11 via the fourth mirror 10. Scanner 4 has pulleys 12 and 13 and drive pulley 1
The scanner 4 scans the document surface for exposure at a predetermined speed from the reference position 2 side, and then reverses and recovers the original surface by scanning the document surface at a predetermined speed from the reference position 2 side. The robot moves and stops near the reference position r. The lens 9 is supported movably in the optical axis direction, is connected to a lens motor 17, and is moved in the optical axis direction by driving of the lens motor 17. A structure may also be adopted in which a mirror block (not shown) on which the second mirror 7 and third mirror 8 are mounted instead of the lens 9 is connected to a motor, and the mirror block is moved in the optical axis direction by the drive of the motor. can. Furthermore, in the case of an apparatus having a magnification converter, a magnification setting motor for driving the lens and mirror block can be used, and switching can be made to drive only the lens or only the mirror block. To simplify the explanation, an example in which a lens is moved will be described below, but it goes without saying that a similar configuration can be used in an example in which a mirror is moved. The lens motor 17 is driven via the lens motor driving device 18 in response to a predetermined start signal, and the lens 9 starts moving by a predetermined amount. A light source 19 and a light sensor 20 are arranged near the lens 9 and slightly offset from the main optical path, as shown in FIG. A condensing lens 21 is placed just in front of the light source 19, for example an LED, and a third mirror 8. A portion of the original 1 on the contact glass (original platen) 3 is irradiated via the second mirror 7 and the first mirror 6. In this case, the optical sensor 20 is positioned and arranged so as to receive the reflected light from the original 1 at a position after passing through the mirror 6.7.8. Immediately in front of the optical sensor 20, an imaging lens 22 is arranged so that the reflected light from the original is imaged on the light receiving surface of the optical sensor 20. With this configuration, when the original 1 is in close contact with the contact glass 3 and the reference position is set to the position where the optical sensor 20 receives the light reflected from the original 1 by the light from the light source 19, the original 1 is lifted up. Since there is a gap between the contact glass 3 and the document surface, the incident position of the illumination light from the light source 19 on the optical sensor 20 changes. By detecting the deviation of this incident position from the reference position, the extent to which the original 1 is lifted can be determined. If the copying magnification of the copying machine is 1:1, from document L to photoconductor 1.
When the lens 9 is located in the center of the optical path up to the photosensitive paper 11, a clear image without blur is formed on the photosensitive paper 11. Therefore, when the lifting of the original 1 occurs and the lifting amount is detected as described above, 1/2 of the detected lifting amount is detected.
By moving the lens 9 toward the original 1 along the optical path by a length equal to , the lens can be positioned in the center of the optical path between the original l and the photoreceptor 11, thereby preventing image blurring. be able to. In other words, if the lens 9 is moved along the optical path according to the amount of lift of the original 1, a clear image without blur can always be obtained. When the copying magnification is other than the same magnification, it is preferable to increase or decrease the amount of movement of the lens 9 depending on the magnification compared to the case of the same magnification. As the optical sensor 20 described above, a semiconductor device detection element (PSD) can be used as an example. The case where the semiconductor device detection element is used as the optical sensor 20 will be described below. As shown in FIG. 3, the semiconductor device detection element is formed as a uniform abrasive layer with nN24 on one side of a high-resistance St substrate 23 and a P-type paper anti-layer 25 on the other side, and exhibits a photoelectric effect due to incident light. , an input electrode 26 on the n layer, a P-type paper anti-layer 25
has a first output electrode 27 and a second output electrode 128 on both sides thereof.
is provided. When the incident light enters the point R of the P-type paper anti-layer 25, a photocurrent (2) is generated due to the photoelectric effect. are the output current ■1 at the first output electrode 27 and the output current I2 at the second output electrode 28
It is divided into In this case, the output current +l, 1g is taken out in inverse proportion to the resistance value from the point of incidence to the respective output electrode. The length of the semiconductor device detection element, that is, the re-output electrode 25,
If the length between 26 and 26 is C1, the total surface resistance is R3, the distance from the center of the semiconductor device detection element to the point of incidence R is X, and the sheet resistance from the center to the point of incidence is R, then if the resistance distribution is uniform, then Since it is RXcex, 1o=I++Ii. In FIG. 4, parallel light from a light source 19 passing through a condensing lens 21 partially illuminates the document surface at a distance 2 from position 0 of the condensing lens 21, and the reflected light passes through the condensing lens 21. If h is the distance from the imaging lens 22 to the light-receiving surface of the semiconductor device detection element 20, which is incident after passing through the imaging lens 22 located at a point 0' located at a distance @B beside the semiconductor device 21, the semiconductor device The deviation lx of the detection element 200 Å from the center of the injection point R is as follows. Assuming that the document surface that is a distance Ml away from the condensing lens 21 is a reference surface in contact with the contact glass, and that the document is lifted up by a distance Δl from this reference surface, the reflected light from the document is reflected by the imaging lens 22. The light is incident on the point R' of the semiconductor device detection element 20 through the light beam, and is deviated from the point R by a distance ΔX. Therefore, Bh BhX−Δ
x"-, ', Δ41!=--11+Δl
x-ΔX In this case, the current ratio a is 1+ C-2(x-Δx)
2 a+1 Therefore, a+1 2Rh Δ2M□・□−2 a−I C is obtained. From this, the floating distance Δl of the original can be determined by knowing the ratio a of each current of the semiconductor device detection element. FIG. 5 is an explanatory diagram for correcting image blur caused by lifting of a document by moving the lens position. In FIG. 5, both output currents 1 and 12 of the semiconductor device detection element are input to the signal calculation device, and the output of the signal calculation device is A/ It is converted into a digital signal using a D converter and taken out as an output voltage proportional to the current ratio of both output currents. For example, as shown in FIG. 6, the signal calculation process by the signal calculation device logarithmically converts the output type 2Itr + from the first output electrode and the output current I2 from the second output electrode using a logarithmic conversion device, and outputs u, , ol in a differential circuit. The output from the A/D converter is compared with the digital output value from the A/D converter as the measurement position based on the signal detected immediately before by the differential means, and the difference is calculated. The difference value as an output is converted into a count number proportional to the difference value and based on the following preset relationship in a count number converter, and the value is set in a counter. Here, the above-mentioned preset relationship is the relationship between the amount of uplift and the amount of lens movement required for blur correction accompanying this. The output value of the differential means mentioned above is the change from the previous measured value,
In other words, since this is the amount of change from the amount of lifting of the document immediately before, the lens is moved by a distance corresponding to this amount. In other words, the count number of the counter indicates the amount of movement of the lens necessary to correct the blurring of the image due to the lifting of the original. The output of the differential means is determined by a positive/negative determining device, and if the output is positive, the lens motor 17 sends a start signal to move the lens 9 toward the document 1, for example, and if it is negative, the lens 9 is moved toward the photoreceptor 11. Occur. The lens is moved by the rotation of the lens motor 17 started by a start signal, and the pulse signal generated by the encoder 29 connected to the lens motor is counted by the counter, and when the count number reaches the set count number, the lens is moved. , a stop signal is sent from the counter to the motor drive device 18 to stop the motor 17. In this way, the lifting amount of the original is detected, and the lens is moved in accordance with the lifting amount, so that the blurring of the original information is corrected and a normal image can be formed on the photoreceptor. FIG. 7 shows an embodiment in which a preliminary scan is performed by the scanner 4 before starting the copying operation, and the scanner 4 is in the preparation position 2.
Preliminary scanning is started from (FIGS. 1 and 8). The scanner 4 is driven by a drive motor 16. At this time, a pulse signal output from an encoder 30 connected to the drive motor 16 is sent to a count calculation device (not shown), and the document is detected as a moving path ML of the scanner 4 from the reference position 2. converted to length. The signal indicating the moving path #L is converted into a document length at predetermined intervals and temporarily stored in a storage device (not shown). When the preliminary scan of the scanner 4 is started, the CPU (not shown)
The scanning reference signal is sent to the lighting device shown in FIG. 7, the storage device, and the counting calculation device (not shown) for calculating the moving length. In this case, the light source 19 connected to the lighting device is turned on at predetermined intervals by the scanning reference signal, irradiating the document surface, and reflected light enters the semiconductor device detection element 20. A count number conversion device that calculates and converts the light incident on the semiconductor device detection element 20 and outputs a count number corresponding to the difference from the previous amount of uplift, and a positive/negative judgment that determines whether the difference from the amount of uplift immediately before is positive or negative. The generation of output signals from each device is as explained in FIG. 5. The count number based on the output signal of the count number conversion device and the positive/negative information that is the output signal of the positive/negative determining device are temporarily stored in a storage device. When the document 1 on the contact glass 3 is lifted as shown in FIG. 8, there is no lifting from the reference position 22 to the moving path ML, and therefore, while the scanner 4 scans from LL to Since there is no rise, the difference between the count number during that time and the count number immediately before it is 0. Travel distance L
When the light a19 is turned on at predetermined intervals after the measurement of a, the scanner 4 has advanced to the position L=L, and the lifting amount of the original 1 at this position is Δ21. Therefore, optical sensor-2
The point of incidence of the incident light on 0 is shifted. This amount of deviation, that is, the lifting position Δ2. The count number corresponding to is immediately before (Δl=
Information regarding the difference between the number of counts at the scanning position (0 position) and its positive/negative difference (pressure in this case) is stored in the storage device at the scanning position L-.
It is temporarily stored together with information regarding L. Similarly, at the next time of lighting, information on the difference Δlx - Δf between the amount of floating Δlz at L ``' L z and the immediately preceding floating information Δl is stored in the storage device, and the next time lighting is performed, the information about the difference Δlx - Δf is stored in the storage device. Information about the amount of floating Δ2.−Δ2.
4 is the difference ΔE, −
Information for Δ23 is stored in the storage device. 1 negative" information. In this way, the amount of uplift is sequentially detected, and difference information and positive/negative information are stored. When the preliminary scanning is thus completed, the copying operation is started. During copying operation, up to L ” Lo, the floating amount Δl-
Since it is 0, the lens motor 17 does not operate and the lens 9 is held at the normal reference position. When the scanner 4 comes to the position L−L, the information stored during the preliminary scan is called up, and the floating amount Δ2=Δ21
For example, in the case of the same size, Δ21/
The lens 9 is moved by 2 and then stops. Further L ””
At the position Lz, the lens is moved in the direction closer to the document l by (Δit-Δff1l)/20 counts to correct the amount of floating. Similarly, the lens 9 is moved at each position by a distance necessary to correct the amount of elevation at that position. L””
In Ls, since the positive/negative judgment is "negative", the lens 9 is moved in the direction closer to the photoreceptor 11. In this way, the copying operation is performed while correcting the position of the lens according to the amount of floating. The shorter the predetermined interval during preliminary scanning, that is, the lighting interval of the light source 19, the more accurately the lens position can be corrected in proportion to the amount of floating, but if it is too short, the operation may be delayed or the memory of the storage device may be damaged. It becomes necessary to increase the capacity. If the predetermined interval is too long, even after correction, some areas will remain where the image will be blurred. Therefore, it is necessary to set an appropriate interval. This predetermined interval is set short, and when the count number output from the count political change a device exceeds the predetermined count number, necessary information such as the count number, positive/negative information, and scanner movement distance is stored in the storage device. As the predetermined count number, it is convenient to select, for example, a count number corresponding to a raised view of a distance equal to the depth of focus of the lens. If you do as above, if the amount of floating is less than the depth of focus of the lens, blurring of the image will not occur, but when the amount of floating is greater than the depth of focus and blurring occurs,
The lens can be moved to be included within the depth of focus range to avoid blurring, and a blur-free image can always be obtained. Setting an upper limit on the amount of lens movement correction equivalent to the amount of lift,
There is also a method of setting the upper limit of the correction amount for cases where the amount of lifting is extremely large. This can prevent the mechanism from becoming complicated due to an increase in the amount of movement of the lens. FIG. 9 shows the change in the lens movement amount with respect to the change in the lifting amount Δ2 of the original, and the lens is moved in stages. As an example of this case, the detected amount of uplift can be taken as the depth of focus r. As the optical sensor, an image sensor (COD) 20' as shown in FIG. 10 can also be used. While the semiconductor device detection element described above detects a change in the position of incident light as a change in the output current ratio, an image sensor only needs to detect a change in the incident pixel number of the incident light. If the pixel pitch of the image sensor is p, the pixel number of the image sensor corresponding to will only change. If the document is raised, in the case of an image sensor, when the light source is turned on once, the light source enters the position of the pixel number corresponding to Δx/p, and charge is accumulated only in that pixel. The pixel number can be confirmed with one scan by the driving device, and if the output is A/D converted,
The digital signal can be processed in the same manner as in the case of FIG. 7, and the position of the lens can be corrected in the same manner as described above to prevent the occurrence of blur. When using an image sensor, the scanning time can be set shorter than the predetermined interval in the example above. Karari! According to the present invention, since the position of the lens is moved in accordance with the amount of lifting of the original, it is possible to prevent blurred images from occurring on the photoreceptor, and it is possible to always make copies that are easy to see. According to the present invention, the light source and optical sensor for detecting floating are arranged at a position away from the main optical path, so that floating can be detected without getting in the way during copying. Since the light source for detecting the lifting amount is blinked at predetermined intervals, lifting amount information can be detected at all times. Prior to exposure scanning for the copying operation, information on the amount of lift on the original is scanned and detected, converted into step-like information, and stored. Therefore, during copying, the lens is scanned and detected in steps based on the information from the storage device. Since the lens is moved and stopped reliably, the lens position can be reliably corrected, and therefore, the correction to eliminate image blur can be reliably performed. Since the floating crab is detected as a digital value of the difference from the previous floating amount measurement value, the amount of movement of the lens only needs to be the change from the previous position, so the amount of movement is small and there is no delay. It can be corrected without fail. Since the amount of lift is stored together with the positive/negative judgment information, the lens can be moved to correct lift with a minimum amount of movement, regardless of whether the lift is increasing or decreasing. . By making the amount of movement of the lens step-like and setting the step interval in relation to the depth of focus of the lens, it is possible to reduce the movement of the lens and reliably correct blur. Further, by setting an upper limit to the amount of lens movement, the lens movement mechanism can be simplified. 4. Brief description of the drawings FIG. 1 is a schematic diagram of a copying machine having a correction device according to the present invention, FIG. 2 is a diagram of a document lifting amount detection means, and FIG.
Figure 4 is an explanatory diagram of an example of an optical sensor, Figure 4 is an explanatory diagram showing the principle of detecting changes in the amount of uplift, Figure 5 is an explanatory diagram of an information processing device that detects the amount of uplift, and Figure 6 is an explanatory diagram of the information processing device that detects the amount of uplift. Fig. 5 is an explanatory diagram of the signal calculation device, Fig. 7 is a diagram of an embodiment of the information processing device, Fig. 8 is an explanatory diagram of preliminary scanning of the floating amount, and Fig. 9 is a change in the lens movement amount and the floating amount. Diagram showing the relationship between
FIG. 0 is a diagram corresponding to FIG. 7 of another modification. l...Original 3...Original table 4...Scanner 5...Lamps 6.7, 8.10...Mirror

Claims (1)

[Claims] An image forming apparatus that exposes and scans a document on a document table and forms a document image on a photoreceptor using an optical device having a group of mirrors, a lens, etc. a D/A converter that converts the output of the detection means into a digital value; and a D/A converter that compares and calculates the difference between the output of the D/A converter and a reference signal. A differential means for outputting an output, a movement amount setting means for setting a movement amount of the lens based on an output signal of the differential means, and a motor drive device for driving and controlling the movement means using a signal from the movement amount setting means. An image correction device for an image forming apparatus based on raised originals, characterized in that: