JPH07245682A - Image reader and copying machine incorporating it - Google Patents

Abstract

PURPOSE:To prevent an event that an original is replaced in mistake even when an original placing area is detected and an original image is read through one reciprocation of a scanning means to improve the efficiency of the image reader. CONSTITUTION:An original placed on an original platen manually by the operator, scanning means 11, 14 apply reciprocal scanning to the original and a CCd 17 converts an image of the original into image information. An identification means identifies an original placing area STUV in the forward operation of the scanning means and original image data corresponding to the original placing area identified by the identification means are outputted in the return operation of the scanning means. An exposure lamp 12 exposing the original in the original scanning is controlled to maintain the lighting state from the forward motion of the scanning means to the return motion of the scanning means.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image reading device and a copying machine incorporating the same.

[0002]

2. Description of the Related Art Recently, an image of a document placed on a document table is converted into an electric signal by a photoelectric conversion element such as a CCD,
An image reading apparatus that generates image data of a document image is known. Usually, the image reading apparatus is implemented in a form incorporated in a part of a digital copying machine or a form connected to a printer or a filing device. It is known that such an image reading apparatus can detect the position of the document on the platen or the position of the image based on the image data.

For example, in Japanese Patent Application Laid-Open No. 61-244169, an image of a document image is discriminated by preliminarily scanning the document before reading the document image, and only the image data of the document image region is output to a printer. A reader is disclosed. In this apparatus, the scanning means is reciprocated once before the image is read, and the original image area is discriminated based on the image data output during that time. However,
In this apparatus, the scanning means for reading one original image needs to make two reciprocating movements, one reciprocal scanning for discriminating the original image area and one reciprocating main scanning for image reading. I won't. That is, in this apparatus, the original is scanned one extra time for preliminary scanning, which is inefficient.

On the other hand, Japanese Patent Publication No. 2-503738 discloses that the document size is detected when the scanning means moves forward and the image is read when the scanning means moves backward. In this apparatus, since the scanning means only needs to reciprocate once to read one original image, the scanning efficiency can be improved and the speed of the image reading apparatus can be increased.

[0005]

However, in the image reading apparatus disclosed in Japanese Patent Publication No. 2-503738, when copying an original placed on the original table by the operator's hand, When prescan (forward) is completed, the operator misunderstands that the image reading of the document is completed, and the document is mistakenly replaced, or the image reading is actually completed when trying to replace the document. There was a situation in which a manuscript that had not been moved was moved. In particular, an operator who is more skilled in operating a conventional analog image reading apparatus has a stronger tendency.

The present invention has been made in view of the above problems, and the reading of the original image is performed during the period from the start of scanning for detecting the state of the original to the end of the operation for reading the original image. An object of the present invention is to provide an image reading apparatus that does not give the operator the misunderstanding that it is completed.

[0007]

In order to solve the above-mentioned problems, the invention according to claim 1 is directed to an original table on which an original is placed, an exposure lamp for exposing the original on the original table, and an exposure lamp on the original table. Based on the scanning means for reciprocally scanning the original, the reading means for reading the scanned original image and outputting the image data, and the original table based on the image data output from the reading means when the scanning means moves forward. A state detecting means for detecting the state of the upper original, an output means for outputting the image data output from the reading means to the outside of the apparatus when the scanning means returns, and a state detecting means for the scanning means. Lighting means for maintaining the exposure lamp in a lighting state from the start of scanning to the end of scanning for the output means.

Further, the invention according to claim 2 is characterized in that the state detecting means detects a position on the original table on which an original is placed.

According to a third aspect of the present invention, a document table on which a document is placed, an exposure lamp that exposes the document on the document table, image light is received, and image data corresponding to the image light is generated. A line sensor fixed to the apparatus for outputting, an optical system for projecting the image light of the original document by the exposure lamp onto the line sensor, and a scanning unit for reciprocally scanning the exposure lamp with respect to the original document, Position detecting means for detecting the position of the original document on the original table based on the image data output from the line sensor when the exposure lamp moves forward, and output from the line sensor when the exposure lamp returns. Output means for outputting image data to the outside of the device,
Lighting means for maintaining the exposure lamp in a lighting state from the start of the scanning of the position detecting means of the exposure lamp to the end of the scanning of the output means.

A fourth aspect of the present invention relates to a copying machine in which the image reading device is incorporated, and a document table on which a document is placed, an exposure lamp for exposing the document on the document table, and an image. A line sensor fixed to the apparatus for receiving light and outputting image data corresponding to the image light, an optical system for projecting the image light of the document by the exposure lamp onto the line sensor, and the exposure Scanning means for reciprocally scanning a lamp with respect to the original, and position detecting means for detecting the position of the original on the original table based on image data output from the line sensor when the exposure lamp moves forward; Creating means for creating an image corresponding to the image data outputted from the line sensor on the sheet in association with the detection result of the position detecting means when the exposure lamp is moved back; During the start of the scan for the position detecting means of the up until the end of the scan for the imaging means, characterized in that a lighting means for maintaining the exposure lamp lighting state.

[0011]

In the image reading apparatus of the present invention, the scanning means reciprocally scans and the image data is generated by the reading means (line sensor). During the forward movement of the scanning means, the state (position) of the document on the document table is detected. When the scanning unit is returned, the image data output by the reading unit is output to the outside of the apparatus. The destination to which the output means outputs the image data is an image forming means of the copying machine when the apparatus is built in the copying machine, or a host computer or the like when the apparatus is an independent apparatus. The exposure lamp is maintained in the lighting state from the forward movement to the backward movement of the scanning means.

[0012]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view showing a digital copying machine to which the present invention is applied. The digital copying machine includes a reading unit 10 which is an image reading apparatus of the present invention, and a printing unit P which forms an image corresponding to image data transmitted from the reading unit 10 on a sheet.

The reading unit IR reads an image of a document placed on the platen glass 19 and generates image data corresponding to each pixel of the image of the document. A first scanner 11 having an exposure lamp 12 and a first mirror 13a
Driven by the second scanner 14 having the second and third mirrors 13b and 13c and the scan motor M2, arrows b and b '.
Direction (sub-scanning direction). The light from the exposure lamp 12 is reflected by the document on the platen glass 19 and is applied to the line sensor 17 via the mirrors 13a, 13b, 13c and the lens 15. The line sensor 17 has a large number of photoelectric conversion elements (CCD) arranged in a direction (main scanning direction) orthogonal to the paper surface of FIG. 1, reads an image at 400 DPI, and outputs image data corresponding to each pixel.
In addition, as described above, the first scanner 11 and the second scanner 1
By moving 4 in the directions of arrows b and b ′, the line sensor 17 can subscan the original image. The sensor SE3 is for detecting that the first scanner 11 is at the home position. The scan motor M
When moving the scanners 12 and 14 in the direction of arrow b, the scanner 2 moves at a higher speed than when moving in the direction of arrow b ′. That is, the scanning of the image by the line sensor 17 when the scanners 12 and 14 move in the direction of arrow b is the preliminary scanning, and the position of the document on the document table is determined based on the image data output from the line sensor 17 at this time. Is detected.
On the other hand, the scanning of the image by the line sensor 17 when the scanners 12 and 14 move in the direction of the arrow b ′ is the main scanning, and the printing of the image is performed based on the image data output from the line sensor 17 at this time. Be seen.

Further, the platen glass 1 of the document cover 50
The surface on the 9 side is colored in orange. As a result, the light reflected by the original cover 50 of the light from the exposure lamp 12 becomes a color having a low spectral sensitivity for the line sensor 17. That is, for the line sensor 17, it is the same as the document cover being black. Therefore, since the background of the document is normally white, the line sensor 17 can distinguish the document from the lower surface of the document cover 50 even when the document cover is closed. Even when the document cover 50 is not closed, the illumination light of the document cover 50 from the exposure lamp 12 does not reach the line sensor 17, and only the illumination light of the document reaches the line sensor 17, so that the document region can be identified. .

The image data output from the line sensor 17 is processed by the image processing unit 20 and then transmitted to the memory unit 30. The memory unit 30 temporarily stores the image data received from the image processing unit,
Alternatively, it is directly transmitted to the print section P.

Next, the print section P will be described. The print processing unit 40 controls the laser optical system 60 based on the image data received from the memory unit 30. The laser optical system 60 emits a laser beam modulated (ON / OFF) controlled by the print processing unit 40, and a laser beam emitted from the semiconductor laser 61 for scanning the photosensitive drum 71. The polygon mirror 62, the fθ lens, the mirror 64a,
64b and 64c.

Around the photosensitive drum 71 which is rotationally driven in the direction of arrow c, along the rotational direction (direction of arrow c), a charging charger 72, a developing device 73, a transfer charger 74, a separation charger 75, and a cleaner 76 are provided. , An eraser lamp 77 is arranged, a toner image is formed by a well-known electrophotographic process, and is transferred onto a sheet. Paper is fed from the paper feed cassettes 81a and 81b to the paper feed roller 82.
It is supplied by a and 82b, and is sent to the position of the transfer charger 74 by the sheet conveying path 83 and the timing roller 84. The sheet on which the toner image is transferred at the position of the transfer charger 74 is ejected onto the sheet ejection tray 88 via the conveyor belt 85, the fixing device 86, and the ejection roller 87.
These various rollers and the photosensitive drum 71 are driven by the main motor M1. In addition, the paper feed cassette 81a,
In the vicinity of 81b, a paper size detection sensor SE1 for detecting the size of the paper stored in each cassette is provided.
SE2 is provided.

Next, the control circuit of this digital copying machine will be described with reference to FIG.

The image processing unit 20 includes a CPU 21 for controlling the timing of the entire apparatus, an A / D converter 22,
The shading correction unit 23, the gradation correction unit 24, the scaling processing unit 25, the line buffer 26, the binarization processing unit 27, the address decoder 28, and the document area detection unit 29 are included. An image reading synchronization signal is supplied from the CPU 21 to each of the line sensor 17, the image processing unit 20, the memory unit 30, and the print processing unit 40.

The signal output from the line sensor 17 for each line is analog data, and this analog data is converted by the A / D converter 22 into digital image data of 8 bits per pixel, and the shading correction unit 23.
After the shading correction is performed in step S1, the gradation correction section 24 performs gradation correction such as MTF correction and gamma correction, and the scaling processing section 25 performs scaling processing. The line buffer 26 stores the image data after the scaling processing for one line. Further, the line buffer 26 sends the stored image data of one line to the document area detection unit 29 when the scanners 11 and 14 move in the b direction (forward movement), and when moving in the b ′ direction (return movement). It also has a switching function for sending the stored image data for one line to the binarization processing unit 27.

The original area detecting section 29 is a platen glass 19
Detect the position of the upper document. Further, the binarization processing unit 27 has 8
After the bit image data is converted into binary data by the error diffusion process, it is transferred to the address in the memory unit 30 designated by the address decoder 28. The memory unit 30 has a capacity enough to store 50 pages of A3 size original. The image memory 31 for one page is 2
It has a dimensional address, and an x address is set in the sub-scanning direction and a y address is set in the main scanning direction. Since this copying machine reads an A3 original at 400 DPI, x is set to 0 to 6799 and y is set to 0 to 4799. Another similar image memory for 49 pages is provided.

The image data written in the memory unit 30 is transferred to the print processing unit 40 based on an instruction from the CPU 21. In the print processing unit 40, the received image data is D / A converted by the D / A conversion unit 41, and the LD drive unit 42 drives and controls the semiconductor laser 61 based on the D / A converted image data. Also, CPU
Reference numeral 21 controls the input and display of signals from various operation keys of the operation panel 90.

Next, the operation panel 90 of the present digital copying machine will be described with reference to FIG.

Reference numeral 900 is a portion for inputting a numerical value such as the number of copies, and a numeric keypad is usually arranged. The message display unit 901 displays various guidances in addition to the set number. Reference numeral 902 denotes a key for selecting one from a plurality of copy magnifications displayed on the magnification display portion 903,
The selected magnification is switched every time the key 902 is pressed. 904 is a paper size display unit 905.
Paper size displayed on (paper cassettes 81a, 8a
This is a key for selecting one of the paper sizes set in 1b and the other paper sizes (not shown), and the selected paper size is switched every time the key 904 is pressed. It is like this. 906
Is automatic paper selection (APS) mode, automatic magnification selection (AM
S) is a key for selecting a mode and a manual mode in which paper selection and magnification selection are manually performed.
Each time the user presses 06, the selected mode is switched. Reference numeral 910 is a key for setting a non-document erasing mode, and 912 is a key for setting a free registration mode. Each key is pressed to set each mode, and the key is pressed again to cancel the setting. When each mode is set, the indicator lamp 9 provided on each setting key
11, 913 lights up.

The outside-original erasure mode and the free registration mode will be described. The outside-original erasure mode is a mode in which an area on which an original is placed is determined, and image data other than the area is erased and output.

The free registration mode is a mode in which the center of the document is always copied to the center of the sheet even when the document is placed on the platen glass 19 at an arbitrary position. Hereinafter, a specific example will be described.

FIG. 4a shows a state in which an A4 size original 55 (see FIG. 4b) is set on the platen glass 19. On the right side and the front side of the platen glass 19, document scales 51 and 52 that serve as guides when setting a document are provided. Original scale 51, 52
Indices 53, 54 corresponding to the sheet size with the front right corner O as the reference position are engraved on the sheet. When the sheet size is designated as A4 and copying is executed without selecting the free registration mode, the image in the area OPQR on the platen glass 19 is copied. Similarly, when A3 size paper is selected, the image in the area OWUX is copied. In the state shown in FIG. 4A, the A4 original 55 has an area O.
It is placed in the area STUV which is deviated from the PQR. Therefore, the original document 55 is set without setting the free registration mode.
If the image is copied to A4 paper, the area OPQR
Only the image of the area SYQZ overlapping with is copied. The copy image thus obtained is shown in FIG. 5a. In addition,
In the figure, the shaded portion is the portion where the image of the document cover 50 appears as a solid black image on the sheet as it is because the outside-document erasing mode is not selected. On the other hand, when the free registration mode is set and copying is performed, as shown in FIG.
As shown in b, the center of the document is automatically detected, and copying is performed so that the image at the center of the document is copied to the center of the paper. Further, when the outside-original erasing mode is selected and copying is performed, it is automatically detected that the original exists only in the area SYQZ of the area OPQR on the platen glass 19, as shown in FIG. 5C, and the area SYQZ is detected. A copy image in which the image outside (the lower surface of the document cover 50) is erased is created. Note that FIG. 5d shows a copy image obtained when both the free registration mode and the out-of-document erasing mode are selected. Similarly, in FIGS. 6a to 6d, when the document is placed in the state of FIG. 4a and the paper size is A3 portrait and the magnification is 1: 1, the document image is copied on the paper according to each mode. It shows the situation.

When the APS mode is selected,
A copyable sheet is automatically selected at a magnification in which a rectangular area OWUX determined by a document setting reference position O and a corner U of the document most distant from the reference position is set. When the AMS mode is selected, the area SYQZ in which the in-frame OPQR corresponding to the selected sheet and the original area STUV overlap each other
However, it is copied at the maximum magnification that fits on the selected paper. It is also possible to consider the binding margin in the APS mode or the AMS mode. It is also possible to combine the out-of-document erasing mode and the free registration mode with the APS mode and the AMS mode.

Next, the CPU in this digital copying machine
An outline of the copying operation under the control of 21 will be described with reference to FIG.

When the copy start button 916 is pressed at time t0, the motor M2 of the reading section 10 drives the scanners 11 and 14, and scanning of the document in the b direction (forward movement) is started. At the same time, the exposure lamp 12 is turned on. When the scanner 11 separates from the home position sensor SE3 at time t1, the line sensor 17 outputs an image signal. At time t2, scanning of the document in the b direction (forward movement) is completed, the scan motor M2 reversely rotates, and the brake is applied. At time t4, the scan motor M2 reverses and scans the original in the b'direction (reverse movement). Start. It should be noted that the scanning speed is set to 16 times higher than that in the backward movement in which the image is read, since only the document placing area needs to be known in the forward movement.

After the time t2, the document area detecting section 29
The document placement position on the platen glass 19 is detected, and the detection result becomes clear at time t3. The document scanning speed is predetermined, and the time (t3-t1) required to detect the document position is also stored in the CPU 21.
Therefore, the time t5 when the line sensor 17 reads the trailing edge of the document and the time t6 when the leading edge of the document is read during the backward movement are the time t5.
It turns out in 3. Then, at time t5, the output of the line sensor 17 is output to the image memory 3 after the above-described image processing.
Written to 1.

Further, the reading of the original is not performed from the time t2 to the time t5, but the exposure lamp 12 is turned on. This is because when the operator manually places the original on the platen glass 19 and makes a copy, it is mistaken that the image reading of the original is completed when the forward movement of the original is completed. This is to prevent the operator from moving or exchanging a document that has not been scanned. In particular, when the outside-original erasing mode or the free registration mode is selected and the enlargement copying is performed, if the original moves, a part of the original image is lost, which is a serious problem. Further, in the case where a high-speed copying machine is performing copying work while manually exchanging many documents, it is particularly important to be prepared for the above situation.

Thereafter, at time t6, the line sensor 17
Is the timing to read the trailing edge of the document, so here
Writing of the original image data to the image memory 31 is completed.

At time t7, the home position sensor SE3 is turned on again. Here, the scan motor M2 is braked to stop, the output of the line sensor 17 is stopped, and the exposure lamp 17 is turned off. Then, the reading of the original image and the writing of the image data in the image memory 31 are completed, the printer unit 100 is activated at time t8, and the reading and image formation of the image data from the image memory 31 is performed at time t9. Will start. At such a timing, the original image is copied on the paper according to the selected copy mode.

In this digital copying machine, as shown in FIG. 7, the platen glass 19 is used during the preliminary scanning (forward movement).
The scanning is performed over the entire area for the purpose of improving the accuracy of detection of the document placing area.

Next, the detection of the document placing area will be described. FIG. 8 shows the structure of the document area detection unit 29.

During forward scanning of the document, the line sensor 17
The output from is temporarily stored in the line buffer 26 after the image processing, and the image data from the line buffer 26 is
It is binarized by a binarizing circuit 291 in the document area detecting section 29. Since the purpose of the binarization circuit 291 is to detect the original area, a simple binarization process is performed unlike the case of the binarization circuit 27. The threshold value is higher than that of the binarization circuit 27, so that erroneous detection will not occur even if there is a large area black image in the document image or the binding portion of the book document is raised. Specifically, the binarization circuit 291 judges that the density level of 256/256 to 200/256 is black, whereas the binarization circuit 27 averages 256/256 to 128 /. The case where the density level is 256 is judged to be black. Further, at this time, the scaling processing unit 2 regardless of the scaling ratio specified by the copy scaling selection key 902.
In 5, the same magnification processing is performed by the magnification signal from the CPU 21.

The image data binarized by the binarizing circuit 291 is stored in the area memory 292 of the original area detecting unit 29 under the instruction of the address decoder 293 by the CPU 21. At this time, the CPU 21 processes the image data string in the main scanning direction in units of 2 bytes (16 pixels), but writes only the image data for one pixel of the most significant bit to the area memory 292. That is, the image data output from the line sensor at a resolution of 400 DPI is stored in the area memory 292 after being thinned by the CPU 21 so that the resolution in the main scanning direction becomes 1/16 (25 DPI).
Further, since the moving speed of the first scanner 11 in the forward movement is increased to 16 times the moving speed in the backward movement, the line sensor 1
When the speed at which 7 scans the original image in the sub-scanning direction is 1
6 times more. On the other hand, since the line sensor 17 is read out under the reference clock of a constant cycle, the resolution of the image read by the line sensor 17 in the sub-scanning direction is 25 DPI which is 1/16 of that in the backward movement in the forward movement. Become. In this way, the area memory 292 stores image data at low resolution (25 DPI) in both the main scanning direction and the sub scanning direction. This is because it is not necessary for the document area detection unit 29 to recognize only the document position, and therefore it is not necessary to recognize the image at the resolution, and the smaller the image data, the shorter the time required for the image processing for detecting the document position. Is. In addition,
The pixel spacing in an image with a resolution of 25 DPI is about 1
Since the size is mm, the position of the document can be detected in units of about 1 mm in this embodiment.

A two-dimensional address of x and y is set in the area memory 292, and the image data stored therein reproduces the state on the platen glass 19. In addition,
In many cases, the document is actually placed with a slight inclination, as shown in FIG.
8A shows a state in which the document is tilted counterclockwise and placed, and FIG. 8B shows a state in which the document is tilted clockwise and placed. In each of FIGS. 8A and 8B, the four end points of the document are labeled S, T, V, U in order from the right in the figure.
Is attached.

As described above, in the embodiment according to the present invention, the exposure lamp 12 that exposes the original at the time of scanning the original is controlled to maintain the lighting state from the forward movement of the scanning means to the backward movement of the scanning means. This indicates to the operator that the image reading operation is continuing.
In addition, it is more effective if the message display section of the operation panel displays that during scanning of the scanning means.

[0042]

According to the present invention, the original state is detected when the scanning means moves forward, and the original image is read when the scanning means moves backward. In other words, the state can be detected and the image can be read for one document only by reciprocating the scanning means once, which is efficient. Moreover, the exposure lamp is turned on from the start of the forward movement of the scanning means to the end of the backward movement. Therefore, even during the switching of the scanning means from the forward movement to the backward movement, there is no possibility that the operator misunderstands that the image reading is completed.

Further, it is desirable that the state detecting means detects the position of the original document when the scanning means moves forward.

The line sensor for reading the image may be fixed to the apparatus as described in claim 3, or may be held integrally with the exposure lamp.

Further, in the case of a copying machine, the read image is immediately reproduced on paper, so if the document moves between the preliminary scan and the main scan, a miscopy can be made. Therefore, the effect is great if it is possible to prevent the operator from moving the document by maintaining the lighting state of the exposure lamp as in the fourth aspect of the invention.

[Brief description of drawings]

FIG. 1 is an internal configuration diagram of a digital copying machine.

FIG. 2 is a control block diagram of a digital copying machine.

FIG. 3 is an operation panel of a digital copying machine.

FIG. 4 shows a document 55 (see FIG. 4b) on the platen glass 1
It is explanatory drawing which shows a mode that it was set up vertically on 9.

FIG. 5 is an explanatory diagram of an out-of-document erase mode and a free registration mode.

FIG. 6 is an explanatory diagram of an outside-document erasing mode and a free registration mode.

FIG. 7 is a time chart of image reading.

FIG. 8 is a configuration diagram of a document area detection unit 29.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Reading part 11 ... 1st scanner (scanning means) 12 ... Exposure lamp 14 ... Optical system 17 ... Line sensor 21 ... CPU

Claims (4)

[Claims] 1. A document table on which a document is placed, an exposure lamp that exposes the document on the document table, a scanning unit that reciprocally scans the document on the document table, and a scanned document image is read. A reading unit that outputs image data, a state detecting unit that detects a state of an original document on the original platen based on image data output from the reading unit when the scanning unit moves forward, and a scanning unit that returns the scanning unit. Output means for outputting the image data output from the reading means to the outside of the apparatus during operation, and from the start of scanning for the state detecting means of the scanning means to the end of scanning for the output means. An image reading apparatus comprising: a lighting unit that maintains an exposure lamp in a lighting state. 2. The image reading apparatus according to claim 1, wherein the state detecting means detects a position on the original table on which an original is placed. 3. A document table on which a document is placed, an exposure lamp that exposes the document on the document table, and an image receiving device that receives image light and outputs image data corresponding to the image light. Line sensor, an optical system for projecting the image light of the original document by the exposure lamp onto the line sensor, a scanning means for reciprocally scanning the exposure lamp with respect to the original document, and a scanning means for moving the exposure lamp forward. Position detecting means for detecting the position of the original on the original table based on the image data output from the line sensor, and the image data output from the line sensor when the exposure lamp is returned to the outside of the apparatus. Output means and lighting means for maintaining the exposure lamp in a lighting state from the start of scanning for the position detecting means of the exposure lamp to the end of scanning for the output means. Image reading apparatus characterized by. 4. A document table on which a document is placed, an exposure lamp for exposing the document on the document table, and an image receiving device for receiving image light and outputting image data corresponding to the image light. Line sensor, an optical system for projecting the image light of the original document by the exposure lamp onto the line sensor, a scanning means for reciprocally scanning the exposure lamp with respect to the original document, and a scanning means for moving the exposure lamp forward. Position detecting means for detecting the position of the original on the original table based on the image data output from the line sensor; and an image corresponding to the image data output from the line sensor when the exposure lamp is returned, Creating means for creating on the paper in relation to the detection result of the position detecting means, and from the start of the scanning of the exposure lamp for the position detecting means to the end of the scanning for the image forming means Copier, characterized in that a lighting means for maintaining the exposure lamp lighting state.