JPS61165777A - Electronic copying machine - Google Patents

Abstract

PURPOSE:To prevent the sticking of unnecessary toner on a photo sensitive body at the time of reduction by changing an irradiating area width of a light source with a shading member to shift in a direction orthogonal to a shifting direction of a photo sensitive body, and controlling a driving means of a shading member in accordance with the detecting result of the reduction ratio detecting means. CONSTITUTION:The rotation of a stepping motor 59 is communicated through a gear 68, a timing belt 58 and a gear 67 to a pinion gear 57, a pair of shading members 52 and 52 are shifted in the mutually approaching direction, and then, a shading plate 52a makes narrow the part to cover a light projecting area of side erasing lamp 53 at respective side parts in a lamp case 54, a dissipating area of the charge in the side end part of a photo sensitive body drum 16 is widened, and the dissipating area of the charge is made narrow by the reverse shifting. The shading member 52 is controlled by judging a copying scale factor from the output condition of a copying scale factor setting switch. The photosensitive body drum 16, which forms the reduced original image, is rotated, the lamp 53 goes to be an installing position, and then, the light projecting area of the lamp 53 is regulated by the shading plate 52a, and only respective side edge parts excluding the shaft length direction length part of the drum 16 corresponding to a reduction scale factor are exposured, and the charge of the part is dissipated.

Description

Detailed Description of the Invention (a) Industrial Application Field The present invention exposes and scans an original through a slit and irradiates reflected light from the original onto a charged photoreceptor. The present invention relates to an electronic copying machine that forms an electrostatic latent image of a document on a document, develops this electrostatic latent image with toner, and transfers the developed toner image onto copy paper.

Conventional electronic copying machines charge a photoconductor by applying a high voltage to the photoconductor, and then irradiate the charged photoconductor with reflected light from the document, which is obtained by exposing and scanning the document. By dissipating the charge on the photoconductor that is irradiated with light, other than the original image.

An electrostatic latent image corresponding to the original image is formed on the photoreceptor.

Next, toner is applied to the formed electrostatic latent image and the image is transferred to copy paper.

In such an electronic copying machine, the photoreceptor has a surface area that corresponds to the entire area of the document table on which the document is placed, and when copying at an equal magnification, if the document is smaller than the document table, the document During t-exposure scanning, unless light is reflected from parts of the document table other than the part on which the original is placed, that is, parts unrelated to the original to be copied, the original image will be formed on the photoreceptor. The charges on the side edges other than the areas where the toner has been removed are not dissipated, and toner is attached and developed. For this reason.

A white lid covering the document table is used to reflect light even if the area around the document on the document table is exposed, but if the lid is left open, unnecessary toner adhesion cannot be avoided. .

If the side edges of the photoconductor that are not necessary for copying, other than the area where the original image is formed, are not exposed and the charge in those areas is not dissipated, very dark toner will adhere to the photoconductor. If a copy is made at the same size on copy paper that is larger than the original, an unnecessary band-like groove will be formed around the original image on the copy paper, degrading the quality of the copy. In addition, toner that has not been completely transferred to the copy paper usually adheres to the photoreceptor even after the transfer, and this residual toner is removed to prevent deterioration of the quality of the copy in the first copying process. However, as mentioned above, very dark toner adheres to the side edges of the photoconductor other than the area where the original image is formed, so all of this toner cannot be completely transferred onto the copy paper. , residual toner adheres to the photoreceptor. In addition, when copying onto copy paper that is the same size as the original, the toner on the side edge of the photoconductor is not transferred to the copy paper, but is completely attached to the photoconductor, and it is necessary to clean and remove this attached toner. teeth,! Not only is this a great burden on the machine, but it also creates an undesirable amount of dust around the machine, and is also less economical due to the large amount of wasted toner. A similar problem occurs when the copy paper is smaller than the original.

In order to solve this problem, the entire surface is initially charged, but the charge on the surface of the photoreceptor is dissipated in the side edge region in the direction perpendicular to the direction of movement of the photoreceptor, which is not necessary for forming an original image. An erasing light source is being considered to
-40540)).

Additionally, a device detects the size of the copy paper and changes the size of the light emitting area of the erasing light source at the side edge in the direction perpendicular to the moving direction of the photoreceptor according to the size (US Pat. No. 3,792,913). ) has also been developed by dissipating the charge on the photoreceptor in areas that do not come into contact with the copy paper.

Prevents unnecessary toner from adhering.

By the way, in recent years, electrostatic copying machines have been developed in which the copying magnification can be changed, reducing the size of the original image.

It is now possible to enlarge and copy the original image, but if you reduce the original image and copy it, the original image formed on the photoreceptor will be the actual original reduced by the set reduction ratio. υ, the charged portion (portion to which toner adheres) on the photoreceptor that is not necessary for copying will spread. However, 1! If the light during optical scanning is reflected and the side edge of the photoreceptor is exposed, the charge in that area will be dissipated, and unnecessary toner adhesion on the side edge of the photoreceptor can be prevented to some extent.
Furthermore, unnecessary adhesion of toner can be prevented to some extent by changing the area of the erasing light source on the side edge of the photoreceptor according to the size of the copy paper mentioned above.
At the time of reduction, unnecessary toner adhesion cannot be completely prevented. That is, when changing the area of the erasing light source according to the above-mentioned copy size, the charge on the side edge of the photoreceptor cannot be completely dissipated because the reduction ratio and the size of the copy paper are unrelated.

Further, the original image can be exposed over the entire area of the original table, and the photoreceptor has a size that allows exposure of the original image on the entire area of the original table.

When copying a reduced original, only the area corresponding to the reduced size of the document glass will be exposed to light reflected from the exposure of the document glass, and the side edges of the photoconductor will be outside the exposed area. Therefore, that part is always not exposed. Therefore, during reduction, the side edges of the photoreceptor are always charged and toner adheres to them, and depending on the prior art, during such reduction.

The charge on the side edge of the photoconductor cannot be completely dissipated,
Unnecessary toner adheres to the side edges of the photoreceptor.

(C) Problems to be Solved by the Invention The present invention has been made based on one or more technical backgrounds. By completely dissipating unnecessary charges around the image and preventing unnecessary toner from adhering to the photoreceptor, it prevents wasted toner and significantly reduces the amount of dust generated per image. Another object of the present invention is to provide an electrostatic copying machine that does not form unnecessary images on copy paper.

The purpose of #II2 of the present invention is to eliminate unnecessary charges around the original image formed on the photoreceptor even during reduction.
To provide an electrostatic copying machine that has a simple structure and can reliably dissipate light with high precision.

A third object of the present invention is to provide an electrostatic copying machine that can dissipate unnecessary charges on each side edge of a photoreceptor by an area equal to the central ice symmetry.

A fourth object of the present invention is that the charge dissipation area can be changed with high precision by using a rack, pinion, and stepping motor, and that the charge dissipation area can be accurately changed by controlling from the home position. Changeable electrostatic copy a
1.

B) Means for Solving the Problems The present invention forms electrostatic latent scratches on a normal-sized or reduced original on a charged photoreceptor that moves in the exposure scanning direction by means of scanning the original with tg light. death.

In an electronic copying machine that develops this electrostatic latent image with toner and transfers the toner image onto copy paper.

a light source arranged in a direction to illuminate a side edge in a direction perpendicular to the direction of movement of the photoreceptor to erase unnecessary charges in that part; The light shielding member includes a light shielding member that changes the width of the irradiation area of the light source by movement thereof, a driving means for the light shielding member, a reduction ratio detection means, and a means for controlling the driving means according to the detection result of the detection means. It is an electronic copying machine that irradiates each of the following.

Another invention is to form an electrostatic latent image corresponding to the original image on a charged photoreceptor by means of optically scanning the original, and to develop this electrostatic latent image with toner. In electronic copying machines that transfer toner images onto copy paper.

In order to illuminate each side edge in a direction perpendicular to the direction of movement of the photoreceptor and dissipate unnecessary charges in that portion, the light sources arranged in that direction intersect with the direction of movement of the photoreceptor. A pair of light shielding members that can be moved by equal distances in opposite directions and that change the irradiation area of the light source on each side edge of the photoreceptor by the respective movements, and driving means for the light shielding members. It is an electronic copying machine.

(E) Function: A light source arranged on the side edge in a direction perpendicular to the direction of movement of the photoreceptor and movable in a direction perpendicular to the direction of movement of the photoreceptor, and by the movement, the irradiation area of the light source is a light-shielding member for changing the light-shielding member, driving means for the light-shielding member, means for detecting a reduction ratio, and means for controlling the driving means according to a detection result of the detecting means, Body movement direction and 1IiL5j! , by selectively illuminating the side edges in the direction of.

Erase unnecessary charges in that part.

(f) Example FIG. 1 is a perspective view of an electronic copying machine according to the present invention.

Figure %2 is the front view showing the internal structure. In these figures, 1 is the copying machine main body;
A document table 2 such as a transparent glass plate is fixed on the upper side, and a hinge i7 is installed on the back side of the main body 1 of the copying machine.
4.4, an automatic document feeder 3 is installed that rotates automatically in the vertical direction, and this automatic document feeder 3
comes into contact with the upper curve of the document table 2 by rotating downward. On one side (right side in the drawing) of the automatic document feeder 3, there is provided a document table 6 on which the original 5 to be copied is placed. A tray 7 is provided on which the next document is placed. A plurality of rollers 8 are provided on the document placement table 6 side of the automatic document feeder 3, and a document conveyance belt 9 is provided in series with these rollers 8 over substantially the entire area in the left and right direction. Rollers 8 are connected to the conveyor belt 9 on the side of the tray 7, and these rollers 86 and the document conveyor belt 9 come into contact with the uppermost document on the document table 6 to transfer the document to the document table 2. , and the copied manuscript is transferred to the tray.
Below, an exposure lamp 10 serving as an exposure scanning device has its axial length direction in the front-rear direction.

The exposure plate 10 is provided so as to be movable in the left-right direction.
A reflector 11 is attached to reflect the light to the side. A @1 movable mirror 12 is attached to the back side of the reflecting mirror 11 to reflect light reflected by the original on the document table 2, and a pair of movable mirrors 12 are attached to the upper left side of the copying machine body Second movable mirrors 13 and 14 are arranged above and below, and reflect the light reflected by the first movable mirror 12 toward the center of the copying machine body 1. Further, an imaging lens 1 is provided approximately at the center of the copying machine body 1.
5 is arranged, and when the exposure lamp 10 scans forward to the right, the document on the document table 2 is exposed to the slit light, and the image of the document is transferred to the first movable mirror. 113.
14 and is reflected toward the light lens 15. The imaging lens 15 is composed of a zoom lens that allows changing the copying magnification. A fixed reflection @17 is provided on the right side of the imaging lens 15.9. Further, a photosensitive drum 16 is disposed on the lower right side of the imaging lens 15.

The original image that has passed through the imaging lens 15 is reflected by a fixed reflecting mirror 17 toward the photosensitive drum 16 .

The original image reflected by the fixed reflection mirror 17 is this fixed reflection @
The light passes through an infrared absorption filter 18 disposed between the photoreceptor drum 17 and the photoreceptor drum 160 and is exposed onto the photoreceptor drum 16 . Furthermore, the zoom ratio of the imaging lens 15 is determined by a copy magnification setting switch.

The photosensitive drum 16 is designed to rotate counterclockwise as shown by the arrow in FIG.

On the upstream side in the rotational direction of the exposure position of the original image on the photosensitive drum 16, there is a site toilet slump 53 for removing (nide erase) the electric charge on the portion of the photosensitive drum 16 corresponding to the side edge of the copy paper. It is provided. A light shielding means is provided around the site toilet slump 53, the detailed structure of which will be described later.

On the upstream side of the photoreceptor drum rotation direction of the photoreceptor slump 53, the photoreceptor drum 16 is uniformly placed in a positive band! (about 600
V) A charging corotron 21 is fixedly installed inside the case 70.

A developing device 23 is disposed downstream of the exposure position of the photoreceptor drum 16 in the rotational direction.
The narcotic latent image formed thereon is developed with toner. The developing device 25 is provided with screw conveyors 22 and 24 that completely stir the carrier and toner. Developing device 23
on the front side.

A toner container 25 (
(See Figure 1) is provided so that it can swing back and forth by a support @26.

A transfer corotron 27 for transferring the toner image on the photoreceptor drum 16 onto gold copy paper is provided downstream in the rotational direction of the photoreceptor drum 16 in the developing device 25, and further downstream of the transfer corotron 27, is photoreceptor drum 1
A separating corotron 28 for separating the copy paper from the photosensitive drum 16 is disposed adjacently, and both the corotrons 27 and 28 are integrally configured to move toward and away from the photosensitive drum 16.

Above the left side of the separation corotron 28, that is, the photosensitive drum 1
A cleaning device 35 for removing toner remaining on the photosensitive drum 16 without being completely transferred to the copy paper is disposed on the rotation direction side of the toner 6 . The cleaning device 65 includes a rubber blade 36 that scrapes off toner on the photoreceptor drum 16.

A screw conveyor 38 is provided for discharging the residual toner scraped off by the blade 36 into a discharge toner storage box 37 (see Figure 1).

Furthermore, a static elimination lamp 39 for removing residual charges on the photoconductor drum 16 is provided on the cleaning device 35 on the side in the rotation direction of the photoconductor drum 16. The charging corotron 21 is disposed at.

A removable paper feed cassette 29 is attached to the lower right side of the copy machine main body 1 at the inner bottom of the copy machine main body 1, and A3 size copy paper is loaded and stored in the paper feed cassette 29. has been done.

At the inner bottom of this paper feed cassette 29, an internal copy paper 19 is provided.
Compression spring 29a and support plate 2 for pressing gold upward
9b is provided to press the copy paper in the paper feed force sector 29 upward. Also.

A paper feed roller 32 is provided above the left side of the paper feed cassette 29, and a paper feed roller 32 is provided at the upper left side of the paper feed cassette 29.
9 is in contact with this paper feed roller 32. A removable paper cassette 33 having the same structure as the paper cassette 29 is installed above the paper cassette 29. A4 size copy paper 19 is stored in the paper cassette 33. These copy sheets 19 are stacked and stored, and are pressed upward by a compression spring 33a and a support plate 331).

The uppermost copy sheet is in contact with the paper feed roller 31.

A base end of a manual paper feed tray 340 for one manual paper feed is rotatably attached near the paper feed loaf 31 in the upper paper feed cassette 33, and its tip is attached to the right side of the copying machine main body 1. It protrudes outward from the surface, and by rotating its tip downward and placing copy paper on the upper surface of this manual paper feed table 34, one manual paper feed is possible.

The copy paper in each paper feed cassette 29, 33 or the copy paper placed on the manual paper feed table 34 is transported by the paper feed rollers 32, 3.
1, and the paper feed low? 36 for transfer Korotkoff 2 f1 separation protron 28. It is conveyed to an upper position, the toner image on the photoreceptor drum 16 is transferred, and it is separated from the photoreceptor drum 16.

A vacuum conveyor 41 is disposed on the left side of the separation corotron 28 in the horizontal direction, that is, on the downstream side in the conveyance direction of the copy paper, and a fixing device 40 is further disposed on the downstream side thereof. The copy paper onto which the toner image has been transferred is conveyed to a fixing device 40 by a vacuum conveyor 41.

The fixing device 40 includes a heat roll 43 with a built-in heater 42 and a pressure roll 44 that is pressed against the heat roll 43, and the unfixed toner on the copy paper is heated by both rolls 43 and 44. , pressurized copy paper 1
It will be fixed at 9. On the downstream side of the fixing device 40 in the copy paper conveyance direction.

A pair of paper ejection rollers 45 and 46 are provided for ejecting the copy paper from the fixing device 40. On the downstream side of the fixing device 40 in the copy paper conveying direction, there is a paper discharge tray 47 on the left side m which receives the copy paper discharged from the fixing device 40.
It is attached so as to extend outward from the copying machine main body 1.

A control box 49 containing a control component 50 is disposed above the fixing device 40, and an exhaust fan 51 is disposed on the left side of the control box 49.

Figure 3 is a plan view of the area around the site toilet slump 53;
@ Figure 4 is a longitudinal sectional view thereof, and Figure 5 is a partially cutaway perspective view thereof. The case 70 of the charging corotron 21 is formed integrally with the case 70 of the charging corotron 21 on the upstream side in the rotational direction of the exposure position on the photosensitive drum 16, that is, on the downstream side of the charging corotron 21, and is parallel to the fine edge of the photosensitive drum 16. body drum 1
A hollow box-shaped guide rail 5 with an open surface facing 6
6 are arranged. Guide grooves 56Pl extending in the axial direction are formed in the upper and lower parts of the opposing inner surfaces of the guide rail 56, respectively, and the guide grooves 56Pl are slidably slidable into each guide groove 56e within the guide rail 56. A pair of engaged light blocking members 52,52 are arranged. Each light shielding member 52
has the same structure.

It is arranged symmetrically with the center of the guide rail 56. One light shielding member 52 has a length approximately equal to the axial length of the guide rail 56. A light shielding plate 52a that covers an open portion facing the photoreceptor drum 16 on one side in the axial direction, and this light shielding plate 521! The upper part of the side plate 521) on the side of the other light shielding plate 52a extends in that direction. A lug 520 is formed on the inner surface of the mounting portion.

A pinion 57 is disposed between both racks 520 at the center of the guide rail 56 and meshes with both racks 520, and the rotation of this pinion 57 causes the rotation of the pinion 57.

Each light shielding member 52 moves at an equal speed in a direction toward each other or in a direction away from each other.

A home position jack 61 is attached to the upper surface of the end side of the guide rail 56 at 52° C. of the side plate of one of the light shielding members 52, and a long hole 561 formed at one side end of the upper surface of the guide rail 56 allows Its upper part is protruding. A home position sensor 60 is attached to the side end portion of the elongated hole 56a on the upper surface of the guide rail 56. This Home Bojinsen F60 has a light-emitting element and a light-receiving element arranged vertically and oppositely on a substrate 6011L. 7f) Interrupter 60°C is attached to a member 6Qa, and this mounting member 60C is attached to a holder fixed to the upper surface of the guide rail 56. 6C1 so that it can slide freely in the axial direction of the guide rail 56, and the mounting member 60Q
is pressed in one direction by a pressure spring 608 interposed between the mounting member 60C and the holder 606L, and its position is regulated by an adjustment screw 60f arranged on the other side of the pressure spring 60e. By rotating the adjustment screw 6Of, the position of the mounting member 60Q, that is, the flap 71'' input taker 60'o is changed. A transparent box-shaped rung case 54 is located within a pair of light shielding members 52 and 52 arranged symmetrically about the center of the separated guide rail 56. It is slidably fitted to each light shielding member 52. On each surface of each light shielding plate 52a of this lamp case 54 facing the side plate 5211.

A light-shielding film 54a is attached to each of the guide rails 56, and the center portion of the open side surface (lower surface) of the guide rail 56 excluding each side in the axial direction, that is, the center excluding the portion facing each side of the photoreceptor drum 16. A light shielding film 54'b is attached to the portion.

A board 53a- is arranged inside the lamp case 54,
Three site lamps 53 are provided on each side of the substrate 53a in the longitudinal direction so as to illuminate the substrate 53a downwardly.
The light emitting area of the six night erase lamps 55 on each side is the same as that of the lamp case 54.
It is separated from the light-shielding film 54N+ attached to the lower surface, and forms each side edge of the photoreceptor dome 16.

Therefore, the light from the site lamp 53 passes through the lamp case 54t'', reaches the side edge of the photoreceptor drum 16, exposes this side edge, and the side edge of the photoreceptor 16 charged by the charging corotron 21. When the light-shielding plate 52!1- of the light-shielding member 52 covers the light emitting area of the nide erase lamp 53, the light from the covered portion is dissipated.

The light does not reach the photoreceptor dome 16, and that portion is not exposed.

The upper end of the pinion 57 that engages with the hook 520 of the light shielding member 52 described above passes through the upper surface of the guide rail 56, and a gear 67 is attached to this upper end. Moreover, above one side of the guide rail 56a (the long hole 56 & formation side).

A stepping motor 59 is installed below its output shaft s9a'1, and a gear 68 is attached to this output shaft 59a.
is installed. A timing belt 58 is wound between this gear 68 and the above-mentioned gear 67, and the rotation of the stepping motor 59 is caused by the rotation of the gear 68. Timing belt 58. The light is transmitted to the pinion gear 57 via the gear 67, and the pair of light shielding members 52, 52 move in a direction toward each other or in a direction in which they move away from each other. Then, by moving the light shielding members 52 in the direction toward each other, the lower light shielding plates 52& narrow the portion covering the light emitting area of the site lamp 530 on each side inside the lamp case 54, and By expanding the charge dissipation area at the side edge of the photoreceptor drum 16 and moving the light shielding members 52 in the opposite direction to separate them from each other, the area covering the light emitting area of the site lamp 53 is expanded and the side edge of the photoreceptor drum 16 is expanded. Narrows the area of charge dissipation in the area.

FIG. 6 is a flowchart for explaining the operation of the light shielding member 52 provided below the site lamp 53. When the copy start button is pressed, first the photo interrupter 601) in the home position sensor f60 is activated.
The output tibe 1 light shielding member 52.52 is at the farthest home position, that is, the side toilet slump 5'5
In other words, the light emitting area of the photosensitive drum 1 is narrowest.
The area where charges are removed at the side edge of 6a is set to be the narrowest. This is because the stepping motor 59 is driven in the reverse direction assuming that the light shielding members 52 and 52 are not at the farthest home position, and the photointerrupter 6013 in the home position sensor 60 is turned on. This is done by stopping the rotation of the stepping motor 590 when the rotation is Z.

Based on this state, control of the light shielding member 52 is started, and the copying magnification is determined from the output state of the copying magnification setting switch, and if the copying magnification is the minimum 0°64x, the stepping motor is 59 is driven in normal rotation by 99 pulses. In addition, in the case of 0.75 times, the stepping motor 59 is driven in normal rotation by 69 pulses, and further 0.75 times.
59 pulses for 78x, 18 for 0.93x
Only the pulses are driven in the normal direction. As a result, the pinion 57 is rotated by a predetermined amount, and the two light shielding members 52 are moved in a direction toward each other. In this case, since the light shielding members 520 racks 52C are formed at equal pitches, the moving distances of both racks 52C are equal. As the light shielding members 52 approach each other, the light projection area below the side-in-slumps arranged on each side expands, and the central part of the photoreceptor drum 16 is not exposed by a length corresponding to each reduction ratio. The other side edges are exposed.

On the other hand, the photosensitive drum 16 is uniformly charged by a charging corotron 27 throughout its axial direction as it rotates, and the document on the document table 2 is charged by an exposure lamp 10.
The original image, which has been exposed to light and reduced to a predetermined magnification by the focusing lens 15, is transferred to the charged photosensitive drum 16t.
``7IX'jtl, the exposed portion on the photosensitive drum 16 has its charge dissipated and the photosensitive drum 16 cools down.
An electrostatic latent image is formed thereon. In this case, since this latent image is a reduced version of the original on the original platen 2, the photoreceptor drum 1
Each end of the document plate 6 in the axial direction becomes an outer portion wider than the original platen 2, and this portion is not exposed to light but is in a charged state.

Photosensitive drum 16 #″l on which a reduced original image is formed
When the photoreceptor drum 16 is further rotated and reaches the position where the id-in-slump 20 is disposed, each end of the photoreceptor drum 16 in the axial direction is illuminated by the light projected from the id-in-slump 20.
i element, and the charge in that part is dissipated. In this case, the light emitting area of the site toilet slump 20 is regulated by the light shielding plate 52 & of each light shielding member 52, and the axial length of the photosensitive drum 160 corresponding to the reduction magnification, that is, the document table 2 is The side inno-slamp 53 prevents only the width dimension when it is reduced by a magnification of charge is dissipated.

The electrostatic latent image formed on the photoreceptor drum 16.

The image is visualized using toner by the developing device 23. That is, toner adheres to the charged portions of the photoreceptor drum 16 that are not exposed to light and becomes visible.

Charges are dissipated on each side of the photoreceptor drum 16 where the original image is not formed by exposure by the site lamp 53 in accordance with the reduction magnification.

No toner is attached to this portion.

The toner image on the photoreceptor drum 16 is transferred to a corotron 2 for transfer.
7 onto a copy paper, and the copy paper is separated from the photosensitive drum 16 by a 1-separation roller 28. Then, the toner image on the copy paper is fixed by a fixing device 40, and the residual toner and residual charge on the photosensitive drum 16 are removed by a cleaning device 35 and a discharge lamp 39, respectively.

Note that the light shielding member 52 in the site lamp 53
The movement may be changed based on the reduction magnification and the size of the copy paper.

(G) Effects of the Invention The present invention includes a light source arranged in the direction perpendicular to the direction of movement of the photoreceptor to illuminate the side edge of the photoreceptor in order to erase unnecessary charges there; A light shielding member movable in orthogonal directions and changing the width of the irradiation area of the light source by the movement, driving means for the light shielding member, and reduction ratio detection means.

Since a means for controlling the driving means according to the detection result of the detecting means is provided, unnecessary charges around the document image formed on the photoreceptor can be completely dissipated.

Further, unnecessary charges can be appropriately dissipated in accordance with changes in the reduction ratio.

[Brief explanation of the drawing]

@ Figure 1 is a perspective view of the electronic copying machine, '@ Figure 2 is its internal configuration diagram,! Figure 3 is a plan view of the area around the site toilet slump, Figure 4 is its vertical sectional view, and Figure 5 is its partially cutaway perspective view.
Figure 6 is a flowchart. 16... Photosensitive drum, 52... Light shielding member, 52a
... light shielding plate, 52C ... rack, 53 ... site toilet slump (light source), 57 ... pinion, 59.
...Stepping motor (drive means).

Claims (1)

[Scope of Claims] 1. By means of exposing and scanning the original, an electrostatic latent image of the same size or reduced original is formed on a charged photoreceptor that moves in the exposure scanning direction, and this electrostatic latent image is In an electronic copying machine that develops an image with toner and transfers the toner image to copy paper, the side edge of the photoreceptor in a direction perpendicular to the direction of movement is irradiated to erase unnecessary charges in that area. a light source arranged in a direction, a light shielding member movable in a direction perpendicular to the moving direction of the photoreceptor and changing the width of the irradiation area of the light source by the movement, a drive means for the light shielding member, and a reduction ratio of the light shielding member. An electronic copying machine comprising: a detection means; and means for controlling the driving means in accordance with a detection result of the detection means. 2. The electronic copying machine according to claim 1, wherein the light sources are disposed opposite to each other at each side edge in a direction perpendicular to the direction of movement of the photoreceptor, and irradiate each side edge of the photoreceptor, respectively. 3. The light shielding member is a pair of members that respectively change the irradiation area of the light source on each side edge of the photoreceptor.
Electronic copying machine as described in section. 4. The electronic copying machine according to claim 3, wherein the pair of light shielding members are moved by equal distances in opposite directions by being driven by a common driving means. 5. The electronic copying machine according to claim 3, wherein the pair of light shielding members each have a rack that engages with four pinions provided between them. 6. The electronic copying machine according to claim 1, wherein the driving means is a stepping motor. 7. The light shielding member is configured to be in a home position with respect to the photoreceptor, and a means for detecting that the light shielding member is in the home position is provided on one side in a direction orthogonal to the moving direction of the photoreceptor. An electronic copying machine according to claim 1. 8. The electronic copying machine according to claim 5, wherein the detection means uses a photocoupler. 9. The photocoupler is movable in the same direction as the moving direction of the light shielding member, and is pressed in one direction by a spring, and a screw that rotates to move the photocoupler against the pressing force of the spring. 9. The electronic copying machine according to claim 8, wherein the position of the photocoupler is regulated by the following. 10. The electronic copying machine according to claim 1, wherein the light shielding member is supported by a support member integrated with a support member of the charging means for the photoreceptor. 11. An electrostatic latent image corresponding to the original image is formed on a charged photoreceptor by a means for exposing and scanning the original, and this electrostatic latent image is developed with toner, and the toner image is printed on copy paper. In an electronic copying machine that transfers images onto a photoreceptor, a light source arranged in each direction and a photoreceptor are used to illuminate each side edge of the photoreceptor in a direction perpendicular to the moving direction of the photoreceptor to dissipate unnecessary charges in that area. A pair of light shielding members that can be moved an equal distance in opposite directions perpendicular to the movement direction and that change the irradiation area of the light source on each side edge of the photoreceptor by their respective movements, and a driving means for the light shielding members. An electronic copying machine characterized by: 12. The electronic copying machine according to claim 11, wherein each of the pair of light shielding members has a rack that engages with one pinion provided between them. 13. The electronic copying machine according to claim 12, wherein the driving means is a stepping motor. 14. The light-shielding member is configured to be at a home position relative to the photoreceptor, and a means for detecting that the light-shielding member is at the home position is provided on one side in the direction of movement of the photoreceptor. The electronic copying machine according to scope item 11. 15. The electronic copying machine according to claim 14, wherein the detection means uses a photocoupler. 16. The photocoupler is movable in the direction of movement of the light shielding member, and is pressed in one direction by a spring, and is moved by a screw that moves the photocoupler against the pressing force of the spring by rotating. 16. The electronic copying machine according to claim 15, wherein the position of the photocoupler is regulated. 17. Claim 1, wherein the light shielding member is supported by a supporting member paired with a supporting member of the charging means for the photoreceptor.
The electronic copying machine according to item 2.