JPH1188595A - Original positioning device, image reader and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent dirt on a white density reference board and creeping of an original under an original scale by providing a notch used to release a thermally expanded part when a positioning member is thermally expanded to both ends of the original positioning member so as to prevent the original scale from being floated out of an original platen. SOLUTION: A transparent plastic-made original scale 52 as a positioning member is fixed to a stay 51 by fixing screws 53, 53 in an original positioning device provided to one side of an original platen. Notches 64, 64 are formed to both ends of the original scale 52 respectively. The notches 64, 64 are placed at the outside of an original width H of a maximum size (at the outside from a scale printing part of the original scale 52). The notches 64, 64 are deeply cut by a depth L that is a multiple of 1.25 of a size l between a line R tying the fixing screws 53, 53 and an original butt face 52a of the original scale 52 to release deformation resulting from thermal expansion of the original scale 52 due to heat of an original illumination light.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a document positioning device, an image reading device, and an image forming device provided in, for example, an electrophotographic apparatus.

[0002]

2. Description of the Related Art A document positioning apparatus of this type has a stay, and a document scale is attached to the stay. The original scale is provided with a white density reference plate. A drive belt is provided on the stay, and the drive belt is stretched between a drive pulley and a driven pulley. A document size indicating needle is attached to the drive belt.

When displaying the size of a document, a driving pulley is rotated by a driving motor and a driving belt is run. As the drive belt travels, the document size indicating hand is moved to a predetermined position to display the size of the read document.

After the size of the document is displayed in this manner, the document is set on the displayed portion, and the document is positioned by abutting against the document abutting surface of the document scale. By the way, the original scale is formed of a transparent plastic material or the like because the original size indicating needle must be visible from the upper part of the apparatus.

[0005] However, when the original scale is made of a plastic material, the heat of the exposure lamp causes the original scale to be thermally deformed and floated, resulting in a gap between the original platen glass and the original abutting surface of the original scale.

When a gap is formed, the leading edge of the document enters the gap, the leading edge position of the document is not determined, and the leading edge of the image is chipped, or the document is set obliquely and the image is inclined. .

In addition, dust and paper dust enter between the white density reference plate attached to the original scale and the platen glass and adhere to the white density reference plate, causing an obstacle to white reference correction. There is a risk that white streaks will occur in the image.

Therefore, in order to prevent the original abutting surface of the original scale from being thermally deformed by the heat of the exposure lamp, the original abutting surface is pressed against the original platen glass by a spring or the like, or the original abutting surface of the original scale is hardly thermally deformed. In order to prevent the white density reference plate from being deteriorated by molding with a member, the original scale is attached to the original platen glass together with the white density reference plate.

[0009]

However, when the original abutment surface of the original scale is formed by a separate member (such as an aluminum window), the mounting accuracy between the original scale and the original abutment surface is required, and the assembling efficiency is reduced. However, there is a problem that the number of parts increases, and the cost increases.

If a spring or the like that presses against the original abutment surface is used, it is necessary to replace the spring due to deterioration of the spring, and it is also necessary to maintain the accuracy of the spring itself, which increases the cost of the parts. Resulting in.

Further, in a case where a separate member is used only at the front end and is attached to the platen glass together with the white density reference plate, if the white density reference plate is deteriorated and needs to be replaced, the entire platen glass must be replaced. Therefore, the maintainability is poor and the cost increases.

The present invention has been made in view of the above circumstances. Even if the original scale thermally expands, it is possible to prevent the original scale from floating from the original mounting table without any special member.
An object of the present invention is to provide a document positioning device, an image reading device, and an image forming device capable of preventing a document from sneaking into a lower portion of a document scale and soiling a white density reference plate.

[0013]

According to the present invention, in order to solve the above-mentioned problems, an object according to the first aspect of the present invention is provided with an original mounting table on which an original is mounted, and an original mounting table provided on the original mounting table for contacting the original. And a notch formed at both ends of the positioning member to release the expansion when the positioning member thermally expands.

According to a second aspect of the present invention, there is provided an original placing table on which an original is placed, a positioning member provided on the original placing table for abutting and positioning the original, and fixing both ends of the positioning member. A first and a second fixing member, and a notch formed in the positioning member between the first and the second fixing member and releasing the expansion when the positioning member thermally expands. .

According to a third aspect of the present invention, there is provided a document table on which a document is placed, a positioning member provided on the document table and having a document abutting surface for abutting and positioning the document.
First and second fixing members for fixing both ends of the positioning member, and formed on the positioning member between the first and second fixing members, the expansion of the positioning member when the positioning member thermally expands First and second notches for releasing the portion, the first and second notches are formed from the document abutment surface toward a line connecting the first and second fixing members, The length is set to be longer than the length from the document abutting surface to the line segment.

According to a fourth aspect of the present invention, there is provided a document table on which a document is placed, a positioning member provided on the document table and having a document abutting surface for abutting and positioning the document.
First and second fixing members for fixing both ends of the positioning member, and formed on the positioning member between the first and second fixing members, the expansion of the positioning member when the positioning member thermally expands First and second notches for releasing the minute,
The first and second notches are formed from the document abutting surface toward a line segment connecting the first and second fixing members,
The length is set to be larger than the length from the document abutting surface to the line segment, and the width W is obtained by the formula W = thermal expansion coefficient of the positioning portion × thickness size × width size / 2 × temperature. .

According to a fifth aspect of the present invention, there is provided an original placing table on which an original is placed, a positioning member provided on the original placing table, for positioning the original by abutting the original, and an original placed by the positioning member. Light scanning means for scanning light,
The light scanning means scans light and receives light reflected from the original to read an original image. The reading means is formed at both ends of the original positioning member. When the positioning member thermally expands, the expansion occurs. And a notch for releasing the minute.

According to a ninth aspect of the present invention, there is provided an original placing table on which an original is placed, a positioning member provided on the original placing table for abutting and positioning the original, and a document positioned by the positioning member. Light scanning means for scanning light,
The light scanning means scans light and receives light reflected from the original to read the original image, and reads the original image, and forms the original image on the image carrier in accordance with the image information read by the reading means. Image forming means, transfer means for transferring an image on the image carrier formed by the image forming means to a transfer receiving body, and formed at both ends of the document positioning member,
A notch for releasing the expansion when the positioning member is thermally expanded.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to an embodiment shown in the drawings. FIG. 1 shows the configuration of a digital copying machine with an ADF function. In the figure, reference numeral 1 denotes an ADF (automatic document feeder) for automatically feeding a document. This A
An ADF tray 2 on which a document is placed is attached to the upper end of the DF 1. A transport belt 3 for transporting the document G is provided inside the ADF 1. Conveyor belt 3
Is provided with a reversing roller 3a and a flapper 3b. A discharge tray 3c is provided above the ADF 1. The ADF tray 2 is provided with a sensor (not shown) for detecting whether or not the document G is placed.

In FIG. 1, reference numeral 4 denotes a copying machine main body, and a document table 5 on which an object to be read, ie, a document G is placed, is provided on the upper surface of the copying machine main body 4. Inside the platen 5
On the lower side, an illumination lamp 6 for illuminating the original G placed on the original table 5, a reflector 7 for condensing illumination light generated from the illumination lamp 6 on the original G, and a reflection from the original G A first carriage 9 as an optical scanning means for reflecting light toward the second carriage 12 is provided.

The first carriage 9 incorporates a first mirror 10 for bending the reflected light from the document G.
The first carriage 9 is arranged so as to be movable in parallel with the original table 5 and is moved in parallel along the original table 5 by a drive motor via a belt or the like described later.

On the second carriage 12, the original G bent via the first mirror 10 of the first carriage 9 is attached.
Mirror 13 and third mirror 13 that sequentially fold reflected light from
Are arranged at right angles to each other.

The second carriage 12 is driven by the first carriage 9 via a wire, which will be described later, for driving the first carriage 9, and the first carriage 9
Are moved in parallel along the document table 5 at half the speed.

Below the first carriage 9, the second
A surface including the optical axis of the light turned back through the carriage 12 is formed so as to be movable via a driving mechanism (not shown), and provides convergence to the reflected light from the first carriage 12, and Is moved to form an image forming lens 17 for forming an image of the reflected light at a desired magnification, and the reflected light condensed through the image forming lens 17 is photoelectrically converted. It has a CCD sensor 18 as reading means for outputting the converted electric signal.

The image forming section 21 includes a light source, ie, a semiconductor laser 22, and changes the intensity of the light from the laser 22 in accordance with the image information of the document G read via the CCD sensor 18, and also changes the recording medium, ie, the photosensitive medium. It has an optical device 25 facing the body 24.

The optical device 25 is provided with a first lens (not shown) that imparts converging properties to the laser light generated from the laser 22 and converts the laser light into a laser light having a substantially circular cross-sectional shape.
A light deflector 26 for deflecting the laser light having a circular cross-sectional shape through a lens along the axial direction of the photoconductor 24, and sequentially deflecting the deflected laser light to a desired position on the photoconductor 24 A second lens 27 for matching the deflection angle of the laser light with the distance from the optical axis on the photoreceptor 24 to the position where the beam is to be formed in order to form an image, and directing the laser light to the photoreceptor 24 And includes a mirror 28 that turns back.

At a substantially central portion of the image forming section 21, a recording medium on which an electrostatic latent image (image) is formed by a laser beam from the optical device 25, that is, a photosensitive member 24 is disposed rotatably in the direction of the arrow. I have. A charging device 31 for charging a predetermined charge on the surface of the photoconductor 24 along the direction of rotation of the photoconductor 24 is provided around the photoconductor 24, and developing is performed by supplying toner to an electrostatic latent image formed on the photoconductor 24. A developing device 32, and an AC voltage applying device 33a for separating the transfer material fed from the paper cassette, ie, the paper P, from the photoreceptor 24.
A transfer device 33 for transferring the toner image formed on the photoconductor 24 to the paper P; and removing the distribution of electric charges on the photoconductor 24 while returning the charging characteristics of the photoconductor 24 to the initial state and scraping off the remaining toner. Cleaning device 34
Are arranged in order.

A self-contained sheet for supplying a sheet P, for example, a copy sheet, an OHP sheet, etc., to the photoconductor 24 at a position corresponding to the rotation direction upstream of the photoconductor 24 and directly below the photoconductor 24. Cassette 36 is inserted. A bypass tray 37 for feeding sheets P having various sizes one by one is provided at a position corresponding to the rotation direction upstream of the photoconductor 24 and to the right of the photoconductor 24.
Is arranged.

Between the photoreceptor 24 and the paper cassette 36, a paper feed roller 38 for drawing out the paper P one by one from the cassette 36, a paper feed roller 39 for feeding the paper P supplied from the bypass tray 37, A pair of conveying rollers 41 for feeding the sheet P pulled out via the paper rollers 38 or 39 toward the photoconductor 24, and a feeding roller for feeding the sheet P from the conveying roller 41 to the photoconductor 24. Route 42,
In addition, while correcting the inclination of the sheet P, the tip of the toner image on the photoconductor 24 is aligned with the tip of the sheet P, and the sheet P is fed at the same speed as the moving speed of the outer peripheral surface of the photoconductor 24. Are disposed.

At a position corresponding to the rotation direction downstream of the photosensitive member 24, a toner image formed on the photosensitive member 24 is transferred, and the transport device transports the sheet P on which the toner is electrostatically attached. 46, a fixing device 4 for melting the toner transferred to the paper P by heating and fixing the toner to the paper P
7, and a pair of discharge rollers 48 for discharging the paper P on which the toner image has been fixed to the outside of the apparatus. Further to the left of the discharge roller 48, a discharge tray 49 for storing the paper P on which the toner image is fixed is disposed.

At the time of image formation, the document G is conveyed to the document table 5 by the ADF 1 and placed thereon, and the document G placed on the document table 5 is irradiated with light from the illumination lamp 6 of the first carriage 9. With the first and second carriages 9,
12 is moved along the document table 5. By this traveling, light is scanned on the original G, and the reflected light from the original is first to third light.
Are transmitted to the imaging lens 17 through the mirrors 10, 13, and 14 of the first embodiment. The reflected light is focused by the imaging lens 17 and
The light is received by the D sensor 18, where it is subjected to photoelectric conversion, and thereafter, an electrical signal (a signal obtained by converting the image of the original G) is output to the image memory.

Thereafter, laser light is emitted from the laser 22 in accordance with the image information of the document G read via the CCD sensor 18. This laser light is transmitted to a first
The light is sent to the light deflector 26 via the lens, and is deflected along the axial direction of the photoconductor 24. This laser light is irradiated on the photoconductor 24 via the second lens 27 and the turning mirror 28. The surface of the photoconductor 24 is uniformly charged by the charging device 31, and an electrostatic latent image corresponding to the original image is formed on the photoconductor 24 by the irradiation of the laser beam. The electrostatic latent image is sent to the developing device 32 by the rotation of the photoconductor 24, and is developed and visualized by supplying toner from the developing device 32. The toner image thus formed is sent to the transfer device 33 by the rotation of the photoconductor 24. At this time, the paper P is supplied from the cassette 36 or the bypass tray 37, and after the paper P is aligned by the timing roller 44, the photosensitive member 24 and the transfer device 3 are transferred.
3 is sent to the image transfer section. Here, the toner image on the photoconductor 24 is transferred to the paper P. The paper P on which the toner image has been transferred is transported by the transport device 46,
The toner image is sent to a fixing device 47, where the toner image is fixed on the sheet P, and then discharged to a discharge tray 49 via a discharge roller 48.
Is discharged.

FIG. 2 is a plan view showing a document positioning device provided on one side of the document table 5. In the drawing, a stay 51 is provided with a transparent plastic document scale 52 as a positioning member. The manuscript scale 52 is formed of a transparent plastic member, and both ends are provided with fixing screws 53 and 5 as fixing members.
3 is fixed to the stay 51. Manuscript scale 5
As shown in FIG. 3, the white density reference plate 55
Is attached to the document table 5 so as to be spaced and opposed. The white density reference plate 55 is irradiated with light from the exposure lamp 6.

A drive belt 56 is provided below the original scale 52 along a white density reference plate 55. The driving belt 56 includes a driving pulley 58 and a driven pulley 59.
And the drive pulley 58 has a drive motor 6
0 is connected. An indicator needle 62 for displaying the size of the document is attached to the drive belt 56.

When displaying the document size, the drive pulley 58 is rotated by the drive of the drive motor 60, and the rotation causes the drive belt 56 to run, so that the pointer 62 moves by the size width of the read document. To display the size of the scanned original. Next, the original G is abutted against the original abutting surface 52a of the original scale 52 in accordance with the displayed original size and positioned.

FIG. 4 is a plan view showing the stay 51 and the original scale 52. Notch portions 64, 64 are formed at both ends of the original scale 52, respectively. These cutouts 64, 64 are located outside the maximum size of the document width H (outside the portion of the document scale 52 where the scale is printed). The notches 64, 64 are deeply cut in a dimension L longer than a dimension l between a line R connecting the fixing screws 53, 53 and the document abutting surface 52a of the document scale 52.
That is, the dimension L of the notches 64, 64 is 1.2, which is the dimension l.
It is formed to be five times as long.

[0037]

[Table 1]

Table 1 shows the maximum gap S formed between the document table 5 and the document abutting surface 52a of the document scale 52 when the exposure lamp 6 is turned on, as shown in FIG. As shown in FIG. 7, the notch portions 64, 64 are not formed in the original scale 52, the notch portions 64, 64 are formed as short as the line segment R connecting the fixing screws 53, as shown in FIG. As shown in FIG.
The case where the length is formed to be 1.25 times as long as the distance to the line segment R connecting 3 and 53 is further compared between the normal temperature and the temperature rise.

FIG. 9 is a graph showing the contents of Table 1. In FIG. 9, the a line indicates notch portions 64 and 6 in the original scale 52.
4, gap change at normal temperature when b is not formed, b
The line is the gap change when the temperature rises, and the c line is the notch 6
4, 64 shows a change in the gap when the temperature rises when the notches 64, 64 are formed long, and the d line shows a change in the gap when the temperature rises when the notches 64, 64 are formed long. It shows the thickness.

The maximum gap S between the document table 5 and the document abutment surface 52a of the document scale 52 is 0.088 mm in thickness of the overseas LT paper even when the temperature of the document scale 52 rises to 65 ° C. by turning on the exposure lamp 6. Don't be over.

In the case of the conventional original scale having no cutouts 64, 64, at normal temperature, 30 degrees from the starting point (abutting reference position).
There is a gap S of 0.05 mm at the position of 0 mm, and there is a gap S of 0.03 mm at other positions, but the document does not enter.

An exposure lamp 6 using a conventional original scale
When is turned on, the distance from the starting point to the position 100 mm from the starting point is 0.1 mm.
A document of 088 mm enters. Notches 64, 6
In the case where 4 is formed as short as the line R connecting the fixing screws 53, a floating of 0.088 mm or more occurs at both ends of 300 mm from the starting point.

The notch portions 64, 64 have a length l from the document abutting surface 52a of the document scale 52 to the fixing screw portions 53, 53.
When the length L is 1.25 times longer than that of
A float of 0.04 mm or more is generated at the position of 00 mm. That is, the cutouts 64, 64 are 1.25 times as long as the length L.
Only when the document G is formed long, even if the document G abuts against the document abutting surface 52a of the document scale 52, the document G does not enter the gap S between the document table 5 and the document abutting surface 52a of the document scale 52. Can be positioned.

The reason why the original scale 52 does not float is because the provision of the notches 64 allows the thermal expansion of the plastic to escape, and the notches 64 are provided.
Is 1.25 times the distance 1 between the document abutment surface 52a and the fixed point.

The width W of the notch 64 of the original scale 53 is determined by the following equation. W = the coefficient of thermal expansion of the original scale × plate thickness × maximum temperature × width dimension / 2 Therefore, for example, the coefficient of thermal expansion of the original scale 53 is 7 × 10 ⁵ / C °, the plate thickness is 2 mm, and the maximum temperature is 65 ° C.
The width W of the notch 64 when the width is 300 mm
W = 7 × 10 ⁵ / C ° × 2 mm × 65 C ° × 300 mm / 2 = 2.73 / 2 mm = 1.365 mm

The reason for dividing by two in the equation is that the notches 64, 64 are formed at two places on the original scale 53. Strictly speaking, however, the length is l / 2-W, so it is better to determine the width in consideration of this.

[0047]

According to the present invention, as described above, the notch for releasing the expansion of the positioning member when the positioning member is thermally expanded is formed in the positioning member of the document, so that the positioning member can be prevented from floating due to thermal expansion. .

Therefore, no gap is formed between the document table and the positioning member, and the document does not enter the gap when the document abuts against the document abutting surface of the positioning member as in the related art. .

Further, since no gap is formed between the original placing table and the positioning member, dust and paper dust do not enter, white correction is normally performed, and white streaks do not occur in the image. Was.

Further, since no special member for regulating the lifting of the positioning member is required, the number of parts can be reduced, and when replacing the parts due to the deterioration of the white density reference plate, it is possible to replace only the positioning member. Since it is good, there is an effect that the maintainability is improved and the cost can be reduced.

[Brief description of the drawings]

FIG. 1 is an internal configuration diagram showing an electrophotographic apparatus according to an embodiment of the present invention.

FIG. 2 is a plan view showing a document positioning device.

FIG. 3 is a cross-sectional view illustrating a document positioning device.

FIG. 4 is a plan view showing an original scale.

FIG. 5 is a plan view showing a state in which a notch is not formed in the original scale.

FIG. 6 is a diagram showing a state in which a notch is formed short in the original scale;

FIG. 7 is a diagram showing a state in which a notch is formed long in the original scale.

FIG. 8 is a diagram illustrating a gap formed by lifting of a document scale.

FIG. 9 is a graph showing a relationship between a position of a document scale from a starting point and a gap amount.

[Explanation of symbols]

 Reference numeral 5: Document table glass (document table) 6: Exposure lamp 51: Stay 52: Document scale 52a: Document abutment surface 53, 53: Fixing screw (fixing member) 55: White density reference plate 56: Drive belt 58: Drive pulley 59 ... Color 60 ... Drive motor 62 ... Pointer G ... Document 64 ... Notch

Claims (12)

[Claims] An original mounting table for mounting an original, a positioning member provided on the original mounting table for abutting and positioning the original, and formed at both ends of the positioning member, wherein the positioning member is thermally A document positioning device, comprising: a notch portion for releasing an amount of expansion when expanded. An original placing table on which the original is placed; a positioning member provided on the original placing table for abutting and positioning the original; and first and second fixing means for fixing both ends of the positioning member. A fixing member, and a notch formed in the positioning member between the first and second fixing members and releasing the expansion when the positioning member thermally expands. Document positioning device. 3. A document mounting table for mounting a document, a positioning member provided on the document mounting table and having a document abutting surface for abutting and positioning the document, and a second member for fixing both ends of the positioning member. A first and a second fixing member, and a first member formed on the positioning member between the first and the second fixing members to release the expansion when the positioning member thermally expands.
And a second notch portion, wherein the first and second notch portions are formed from the document abutment surface toward a line segment connecting the first and second fixing members,
A document positioning device, wherein the length is longer than the length from the document abutting surface to the line segment. 4. A document mounting table for mounting a document, a positioning member provided on the document mounting table and having a document abutting surface for abutting and positioning the document, and a second member for fixing both ends of the positioning member. First and second fixing members, and first and second notches formed in the positioning member so as to be located between the first and second fixing members, and for releasing the expansion when the positioning member thermally expands. And the first and second notches are formed from the document abutment surface toward a line segment connecting the first and second fixing members,
The length is greater than the length from the original abutment surface to the line segment, and the width W is obtained by the following equation: W = Thermal expansion coefficient of the positioning section × thickness × width / 2 × temperature An original positioning device, comprising: 5. An original mounting table on which an original is mounted, a positioning member provided on the original mounting table for abutting and positioning the original, and an optical scanner for scanning the original positioned by the positioning member with light. Means for scanning the light by the light scanning means and receiving light reflected from the original to read and read the original image; and forming at both ends of the original positioning member, the positioning member thermally expanded. A notch for allowing the expansion to escape. 6. An original mounting table for mounting an original, a positioning member provided on the original mounting table for abutting and positioning the original, and an optical scanner for scanning the original positioned by the positioning member with light. Means for scanning the light by the light scanning means and receiving light reflected from the document to read and read the image of the document, and first and second fixing members for fixing both ends of the positioning member; A notch formed in the positioning member between the first and second fixing members to release an expansion when the positioning member thermally expands. . 7. A document placing table on which a document is placed, a positioning member provided on the document placing table and having a document abutting surface for abutting and positioning the document, and a light beam applied to the document positioned by the positioning member. Light scanning means for scanning the light, light scanned by the light scanning means, receiving light reflected from the document and reading and reading a document image, and first and second fixing means for fixing both ends of the positioning member 2, a first and a second notch formed in the positioning member and located between the first and second fixing members, to release the expansion when the positioning member thermally expands, Wherein the first and second notches are formed from the document abutment surface toward a line connecting the first and second fixing members,
An image reading apparatus, wherein the length is longer than the length from the document abutting surface to the line segment. 8. A document mounting table on which a document is mounted, a positioning member provided on the document mounting table and having a document abutting surface for abutting and positioning the document, and light on the document positioned by the positioning member. Light scanning means for scanning the light, light scanned by the light scanning means, receiving light reflected from the document and reading and reading a document image, and first and second fixing means for fixing both ends of the positioning member 2, a first and a second notch formed in the positioning member and located between the first and second fixing members, to release the expansion when the positioning member thermally expands, The first and second notches are formed from the document abutting surface toward a line segment connecting the first and second fixing members,
The length is set to be larger than the length from the original abutment surface to the line segment, and the width W is obtained by the following equation: W = the coefficient of thermal expansion of the original positioning portion × thickness × width × 2 × temperature. An image reading apparatus, comprising: 9. A document mounting table on which a document is mounted, a positioning member provided on the document mounting table for abutting and positioning the document, and an optical scanner for scanning the document positioned by the positioning member with light. Means for scanning the light by the light scanning means and receiving light reflected from the original to read the original image, and reading means for reading the original image; and reading the original image on the image carrier in accordance with the image information read by the reading means. Image transfer means for transferring an image on the image carrier formed by the image formation means to a transfer-receiving member; formed at both ends of the document positioning member; And a notch for allowing the expansion to escape when the image is formed. 10. An original mounting table for mounting an original, a positioning member provided on the original mounting table for abutting and positioning the original, and an optical scanner for scanning the original positioned by the positioning member with light. Means for scanning the light by the light scanning means and receiving light reflected from the original to read the original image, and reading means for reading the original image; and reading the original image on the image carrier in accordance with the image information read by the reading means. Image forming means for forming an image, transferring means for transferring an image on the image carrier formed by the image forming means to a transferred body, and first and second fixing members for fixing both ends of the positioning member And a notch formed in the positioning member between the first and second fixing members and releasing the expansion when the positioning member thermally expands. Location. 11. A document mounting table on which a document is mounted, a positioning member provided on the document mounting table and having a document abutting surface for abutting and positioning the document, and a light beam applied to the document positioned by the positioning member. Optical scanning means for scanning an original; scanning light by the optical scanning means; receiving light reflected from the original; and reading and reading an original image; and an image corresponding to image information read by the reading means. Image forming means for forming a document image on a carrier; transfer means for transferring an image on the image carrier formed by the image forming means to a transfer target; first and second fixing means for fixing both ends of the positioning member; A second fixing member, and first and second notches formed in the positioning member so as to be located between the first and second fixing members and releasing the expansion when the positioning member thermally expands. , And Bei, the first and second notched portions are formed toward the line segment connecting the first and second fixing members from the document abutting surface,
An image forming apparatus, wherein the length is longer than the length from the document abutting surface to the line segment. 12. A document mounting table on which a document is mounted, a positioning member provided on the document mounting table and having a document abutting surface for abutting and positioning the document, and a light beam applied to the document positioned by the positioning member. Optical scanning means for scanning an original; scanning light by the optical scanning means; receiving light reflected from the original; and reading and reading an original image; and an image corresponding to image information read by the reading means. Image forming means for forming a document image on a carrier; transfer means for transferring an image on the image carrier formed by the image forming means to a transfer target; first and second fixing means for fixing both ends of the positioning member; A second fixing member, and first and second notches formed in the positioning member so as to be located between the first and second fixing members and releasing the expansion when the positioning member thermally expands. , Previous The first and second notched portions are formed toward the line segment connecting the first and second fixing members from the document abutting surface,
The length is set to be larger than the length from the original abutment surface to the line segment, and the width W is obtained by the following equation: W = the coefficient of thermal expansion of the original positioning portion × thickness × width × 2 × temperature. An image forming apparatus.