JPS6292973A - Electronic copying machine - Google Patents

Abstract

PURPOSE:To remove completely unnecessary electric charge around an original image on a photosensitive body at the reduction time by providing a light shielding member which changes the width of the irradiated area of a side erase lamp and controlling the width of the light shielding member in accordance with a reduction magnification. CONSTITUTION:A side erase lamp 53 which irradiates the side edge parts of the photosensitive body is provided in a lamp case 54, and a pair of light shielding members 52 consisting of light shielding plates 52a and racks 52c are provided in a guide rail 56. Light shielding members 52 approach and are separated from each other through a pinion 57 driven by a stepping motor 59 and a timing belt 58. In case of copying, the motor 59 is driven in accordance with the reduction magnification to control the width of light shielding members 52. Thus, unnecessary electric charge around the original image on a photosensitive drum 16 is removed completely.

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.

(b) Conventional technology Electronic copying machines charge a photoconductor by applying a high voltage, and then irradiate the charged photoconductor with reflected light from the document obtained by exposing and scanning the document. By dissipating the charge on the photoconductor other than the original image irradiated with light, an electrostatic latent image corresponding to the original image is formed on the photoconductor, and then the formed electrostatic latent image area By applying toner and developing it, the developed image is transferred to copy paper.

In such electronic copying machines, 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 the same magnification, if the document is smaller than the document table, the document will not be exposed. When scanning, unless the light is reflected from a part of the document table other than the part where the original is placed, that is, a part unrelated to the original to be copied, the part on the photoconductor where the original image is formed Charges on the other side edges are not dissipated and toner is attached and developed. For this reason, a white lid is used to cover the document table so that light is reflected even if the area around the document on the document table is exposed. 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 image will be formed around the original image on the copy paper, degrading the quality of the copy. Additionally, toner that could not be transferred to the copy paper usually adheres to the photoreceptor even after transfer, and it is necessary to remove this residual toner in order to prevent deterioration in the quality of copies in the next 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 will not be transferred to the copy paper and will adhere to the photoconductor, and this attached toner will need to be cleaned and removed. This not only adds a lot of weight to the machine, but also creates an undesirable amount of dust around the machine, and also reduces economy 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, initially the entire surface was covered with '4'.
However, an erasing light source has been considered that dissipates the charge on the surface of the photoreceptor 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 (Japanese Patent Publication No. 5).
(See Publication No. 3-405408).

Furthermore, a device that 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 orthogonal to the moving direction of the photoreceptor according to the size (US Pat. No. 3,792,913) A method of preventing unnecessary toner adhesion by dissipating the charge on the photoreceptor in areas that do not come into contact with the copy paper has also been developed.

By the way, in recent years, static i
1 [Copying machines have been developed, and it is now possible to reduce or enlarge the original image and copy it. However, when reducing the original image and copying it, the original image formed on the photoreceptor is The actual document is reduced according to the set reduction ratio, and the charged portion (the portion to which toner adheres) on the photoreceptor, which is not necessary for personal photography, is spread out. However, if the light during exposure scanning is reflected from a part of the document table other than the part on which the original is placed, and the side edge of the photoconductor is exposed, the charge on that part is dissipated and the photoconductor side Unnecessary toner adhesion on the edges can be prevented to some extent, and unnecessary toner adhesion can also be prevented by changing the area of the erasing light source on the side edges of the photoreceptor according to the size of the copy paper mentioned above. Although adhesion can be prevented to some extent, it is not possible to completely prevent unnecessary toner adhesion during reduction. 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.

In addition, the exposure of the original image is possible over the entire area of the original platen, and the photoreceptor has a size that allows the exposure of the original image of the entire area of the original platen, but when the original is reduced and copied. In this case, only the area corresponding to the size of the reduced original platen is exposed by the reflected light from the exposure of the original platen, and the side edges of the photoreceptor are outside the exposed area, so that part is always not exposed. . Therefore, during reduction, the side edges of the photoreceptor are always charged and toner adheres to them.Depending on the prior art, the charges on the side edges of the photoreceptor cannot be completely dissipated during such reduction, resulting in undesirable results. The necessary toner adheres to the side edges of the photoreceptor.

(/M Problems to be Solved by the Invention The present invention has been made against the above-mentioned technical background, and its first purpose is to reduce the size of the document formed on the photoreceptor during reduction. By completely dissipating unnecessary charges around the image and preventing unwanted toner from depositing on the photoreceptor, toner waste is prevented, the amount of dust created is significantly reduced, and The object of the present invention is to provide an electrostatic copying machine that does not form unnecessary images on copy paper.

A second object of the present invention is to provide an electrostatic copying machine that can reliably dissipate unnecessary charges around a document image formed on a photoreceptor with a simple structure and with high precision even during reduction. It is in.

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 areas that are centrally symmetrical.

A fourth object of the present invention is to change the charge dissipation area with high precision by using a rack, pinion, and stepping motor, and to accurately change the charge dissipation area by controlling from the home position. To provide a changeable electrostatic copier.

A fifth object of the present invention is to move the center of the unnecessary charge dissipation area on each side edge of the photoreceptor, thereby moving the center of the unnecessary charge dissipation area and the document image on the photoreceptor. An object of the present invention is to provide an electrostatic copying machine that can easily match centers.

B) Means for Solving the Problems The present invention forms an electrostatic latent image of a normal or reduced original on a charged photoreceptor that moves in the exposure scanning direction by means of exposing and scanning the original. However, in an electronic copying machine that develops this electrostatic latent image with toner and transfers the toner image to copy paper, the side edges in the direction perpendicular to the direction of movement of the photoreceptor are irradiated to remove unnecessary parts. A light source arranged in the direction to erase charges, a light shielding member that is movable in a direction perpendicular to the direction of movement of the photoreceptor and changes the width of the irradiation area of the light source by the movement, and a light shielding member that changes the width of the light shielding area by the movement. An electronic copying machine comprising means for moving the center, means for driving the light shielding member, means for detecting a reduction ratio, and means for controlling the driving means according to the detection result of the detection means. It is.

Another invention is to form an electrostatic latent image corresponding to the original image on a charged photoreceptor by means of exposing and scanning the original, and to develop this electrostatic latent image with toner. In an electronic copying machine that transfers a toner image onto copy paper, each side edge in a direction perpendicular to the direction of movement of the photoconductor is irradiated to dissipate unnecessary charges in that area (light sources arranged in each direction). and a pair of light shielding members that can be moved an equal distance in opposite directions orthogonal to the moving direction of the photoreceptor, and that change the irradiation area of the light source that can reach each side line portion of the photoreceptor by their respective movements, and the light shielding area. The electronic copying machine includes means for moving the center of the width and means for driving the light shielding member.

(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 the width of the irradiation area of the light source can be changed by the movement. a light-shielding member to be changed; a means for moving the center of the light-shielding region;
A means for driving the light shielding member, a means for detecting a reduction ratio, and a means for controlling the driving means according to the detection result of the detecting means are provided. The side edges are selectively irradiated to erase unnecessary charges in that area.

(Embodiment 1 Fig. 1 is a perspective view of an electronic copying machine according to the present invention, and Fig. 2 is a front view showing the configuration of 1p of the electronic copying machine. In these figures, 1 is the main body of the copying machine, and this - A manuscript table 2 made of a transparent glass plate is fixedly installed on the upper side of the copying machine main body 1, and a hinge 4.
4, an automatic document feeder 3 is attached which serves as a vertically rotating mark, and this automatic document feeder 6 comes into contact with the upper surface of the document table 2 when rotated downward. On one side of the automatic document feeder 3 (on the right side in the drawing), a document placement table 6 is provided on which a document 5 to be copied is placed.
On the other side (the left side in the drawing), the manuscript after copying is placed in a
A tray 7 is provided for placing the paper. Automatic document feeder 3
A plurality of rollers 8 are provided on the side of the document placement table 6 in , 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 arranged in series on the side, and these rollers 8 and document transport belt 9 contact the uppermost document on the document table 6, transfer the document to the document table 2, and then copy it. The original document is transferred onto a tray 7.

An exposure lamp 10 serving as an exposure scanning device is provided below the document table 2 so as to be movable in the left and right directions with its axial direction being the front and back direction. A reflecting mirror 11 is mounted to reflect the light from the lamp toward the document table 2 side. On the back side of this reflecting mirror 11,
A first movable mirror 12 is attached to reflect light reflected by a document or the like on the document table 2, and a pair of second movable mirrors 13 and 14 are mounted on the upper left side of the copying machine main body 1, vertically. The light reflected by the first movable mirror 12 is reflected toward the center of the copying machine body 1. Further, an imaging lens 15 is arranged approximately in the center of the copying machine main body 1.
When the exposure lamp 10 scans forward to the right, the original on the original table 2 is exposed to slit light, and the image of the original is transferred to the first movable mirror and to the imaging lens 15 by the pair of second movable fi13 and j4. reflected towards. The imaging lens 15 is composed of a zoom lens that allows changing the copying magnification. A fixed reflecting mirror 17 is provided on the right side of the imaging lens 15, and a photoreceptor drum 16 is arranged on the lower right side of the imaging lens 15. is reflected toward the photosensitive drum 16 by the fixed reflecting mirror 17 .

The original image reflected by the fixed reflecting mirror 17 passes through an infrared absorption filter 18 disposed between the fixed reflecting mirror 17 and the photosensitive drum 16, and is exposed onto the photosensitive drum 16. Note that the zoom ratio of the imaging lens 15 is determined by a copy magnification setting switch.

The photosensitive drum 16 is designed to rotate in a clockwise direction as shown by the arrow in FIG.
A site toilet slump 53 is provided for removing (site erasing) the electric charge from a portion of the photosensitive drum 16 corresponding to the side edge of the copy paper. 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 6o
o V) The charging corotron 21 is in case 7.
Fixed within 0.

A developing device 23 is disposed downstream of the exposure position of the photoreceptor drum 16 in the rotational direction.
The electrostatic latent image formed thereon is developed with toner. The developing device 23 is provided with screw conveyors 22 and 24 that stir the carrier and toner. Developing device 23
A toner container 25 (see FIG. 1) for supplying toner to the developing device 23 is provided on the front side of the developing device 23 so as to be able to swing back and forth on a support shaft 26.

A transfer corotron 27 that transfers the toner image on the photoreceptor drum 16 onto copy paper is provided downstream in the rotational direction of the photoreceptor drum 16 in the developing device 23, and further downstream of the transfer corotron 27. is photoreceptor drum 1
Separating corotron 28 for separating copy paper from 6-
are arranged adjacent to each other, and both corotrons 27 and 28 are configured to move toward and away from the photosensitive drum 16 as a unit.

Above the left side of the separating 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 35 includes a rubber blade 36 that scrapes off the toner on the photoreceptor drum 16, and discharges the residual toner scraped off by the blade 56 into a waste toner storage box 37 (see FIG. 1). It is equipped with a screw conveyor 38.

Furthermore, a static elimination lamp 39 for removing residual charges on the photoconductor drum 16 is provided on the cleaning device a55 on the side in the rotation direction of the photoconductor drum 16. The charging flotron 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 upward
9fi is provided to press the paper sheets in the paper feed cassette 29 upward. Further, a paper feed roller 32 is provided above the left side of the paper feed cassette 29, and the uppermost copy paper 19 in the paper feed cassette 35 is transferred to the paper feed roller 32.
is in contact with. A removable paper cassette 33 having the same structure as the paper cassette 29 is installed above the paper cassette 29, and A4 size copy paper 19 is loaded in the paper cassette 33. The stored copy sheets 19 are pressed upward by the compression spring 63a and the support plate 33b, and the top copy sheet is in contact with the paper feed roller 51.

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

The copy paper in each paper feed unit 1-29.33 or the copy paper placed on the manual paper feed tray 64 is transferred to the paper feed roller 32.
31, and is temporarily stopped by a pair of register rollers 72.73 in front of the paper feed roller 32.31, and then moved to the upper position of the transfer corotron 27 and the separation corotron 28X) below the photoreceptor drum 16. The toner image on the photoreceptor drum 16 is transferred and separated from the photoreceptor drum 16.

A vacuum conveyor 41 is disposed on the left side of the front two-separation corotron 28 in the horizontal direction, that is, on the downstream side in the conveying direction of the copy paper, and roughly downstream of the vacuum conveyor 41, a fixing device 40 is disposed to fix the toner image. The copy paper onto which 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. A pair of paper ejection rollers 45 and 46 for ejecting the copy paper from the fixing device 40 is provided on the downstream side of the fixing device 40 in the copy paper conveying direction. This fixing device f is located downstream of the fixing device 40 in the copy paper conveyance direction.
Paper ejection tray 4 that receives copy paper ejected from ft40
7 is attached with its left side extending outward from the copying machine main body 1.

A control box 49 in which a control component 50 is installed is disposed above the fixing mount 40, and an exhaust fan 51 is disposed on the left side thereof.

FIG. 3 is a plan view of the area around the site toilet slump 53, FIG. 4 is a vertical sectional view thereof, FIG. 5 is a partially cutaway perspective view thereof, FIG. 6 is a sectional view taken along line A-A in FIG. is an exploded perspective view. A 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 axis of the photosensitive drum 16. A hollow box-shaped guide rail 56 whose surface facing the photoreceptor drum 16 is open is provided. A sliding plate 62 is attached to the guide rail 56 by two stepped screws 70 passing through its elongated hole 62b. It is inserted into the hole 63a. Guide grooves 56a extending in the axial direction are formed in the upper and lower parts of each opposing inner surface of the guide rail 56, and a guide groove 56a is formed in the guide rail 56 to slidably engage with each guide groove 56a. A pair of light shielding members 52 and 52 are arranged. Each light shielding part group 5
2 has the same structure and is arranged symmetrically to the center of the guide rail 56. One of the light shielding members 52 has a length of approximately 174 times the axial length of the guide rail 56, and includes a light shielding plate 52a that covers an open portion facing the photoreceptor drum 16 on one side in the axial direction; A side plate 521) is provided upright on the side of the light shielding plate 52a in the rotational direction of the photoreceptor drum 16, and the upper part of the side plate 52b on the side of the other light shielding plate 52a extends in that direction. A lug 52c is formed on the inner surface of the extension portion. A pinion 57 attached to a sliding plate 62 is disposed between both racks 520 at the center of the guide rail 56 so as to mesh with both racks 520. As the pinion 57 rotates, each light shielding member 52 is mutually disposed. in the direction approaching or away from each other,
Move at equal speed.

A home position shutter 61 is attached to the upper surface of the side plate 52b of one of the light shielding members 52 on the end side of the guide rail 56.
Elongated holes 56a and 6 formed at one side end of the upper surface of
Its upper part protrudes from 2C. A home position sensor 60 is attached to the side end portion of the elongated hole 620 on the upper surface of the sliding plate 62 . This home position sensor 60 is a photo interrupter 601 in which a light emitting element and a light receiving element are disposed vertically facing each other on a substrate 60a.
) is attached to the member 60C, and this attachment member 60C is attached to the holder 60 (1,
The mounting member 60Q is attached to the mounting member 60C so as to be slidable in the axial direction of the guide rail 56.
and the holder 60 (1) is pressed in one direction by a pressure spring 60e interposed between the pressure spring 60e and its position is regulated by an adjustment screw 60f disposed on the other side of the pressure spring 60e. By rotating the mounting member 60
Q, that is, the position of the photo interrupter 60b is changed.

The upper part of the home position shutter 61 mentioned above is located between the light emitting element and the light receiving element of the photo interrupter 601), and when the double speed light member 52 reaches the separation limit position, the home position shutter 61 emits light. A photo interrupter 60 is located between the element and the light receiving element.
b is turned off.

A transparent box-shaped lamp case 54 is slidably fitted into a pair of light shielding members 52 and 52 arranged symmetrically about the center of the guide rail 56 . Side plate 521 of each light shielding plate 52a in this lamp case 54)
A light-shielding film 54a is attached to each surface facing the photosensitive drum 16, and the central portion of the open side surface (lower surface) of the guide rail 56 excluding each side in the axial direction, that is, the photosensitive drum 16.
A light-shielding film 541) is attached to the central portion of the screen, excluding the portions facing each side.

A substrate 53a is disposed inside the lamp case 54, and three site lamps 53 are provided on each side of the substrate 53a in the longitudinal direction.
The light emitting area of the three site lamps 53 on each side is located outside the light-shielding film 54N attached to the lower surface of the lamp case 54.
These are the side edges of the photosensitive drum 16.

Therefore, the light from the cytotoilet lamp 53 passes through the lamp case 54 and reaches the side edge of the photoreceptor drum 16 to expose the side edge of the photoreceptor 16, which is charged by the charging corotron 21. It is designed to dissipate electric charge,
Furthermore, when the light-shielding plate 52a of the light-shielding member 52 covers the light projection area of the site lamp 53, the light from the covered portion does not reach the photoreceptor drum 16, and that portion is not exposed.

The upper end of the pinion 57 that meshes with the rack 52C of the light shielding member 52 described above passes through the upper surface of the guide rail 56 and the lower surface of the sliding plate 62, and a gear 67 is attached to this upper end. There is. Further, above one side of the guide rail 56a (the side where the long hole 56a is formed), a stepping motor 59 is installed with its output shaft 59a facing downward, and a gear 68 is attached to this output shaft 59a. There is.

A timing belt 58 is connected to and rotated between this gear 68 and the above-mentioned gear 67, and the rotation of the stepping motor 59 is transmitted to the pinion gear 57 via the timing belt 58 and the gear 67. light shielding member 5
2.52 move toward each other or away from each other. By moving the light shielding members 52 in the direction toward each other, the lower light shielding plate 52a narrows the portion covering the light emitting area of the site lamp 53 on each side inside the lamp case 54, and By widening the charge dissipation area at the side edges of the light shielding members 52 and moving the light shielding members 52 in a direction that separates them from each other,
The portion of the slump 53 that covers the light projection area is widened to narrow the charge dissipation area at the side edge of the photoreceptor drum 16.

The aforementioned connecting member 63 has a pressing spring 6 interposed between it and a supporting member 64 to which the stepping motor 59 is attached.
7 to one side.

Further, the connecting member 63 and a supporting member 69 attached to the stepping motor 59 are integrated with a screw 65 via a metal 66. Since the metal 66 is slidable along the long hole 64b of the support member 64, the stepping motor 59, its support member 69, the connecting member 63, and the sliding plate 62 press against the support member 64. By rotating the flattering screw 68 passing through the spring 67, the stepping motor 59 moves in the same direction as the light shielding member 52 while keeping the distance between the output shaft 59a and the pinion 57 constant, and the photosensitive drum 16 The center position of the charge dissipation region at the side edge of the charge dissipation region can be adjusted.

FIG. 8 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 photointerrupter 60b in the home position sensor 60
The output of the double-speed light members 52 and 52 is located at the farthest home position, that is, the state where the light emitting area of the erase lamp 56 is narrowest, in other words, the photoreceptor drum 16
The region from which charges are removed at the a-side edge is set to be the narrowest. This means that if the photointerrupter 60b is in the ON state, the stepping motor 59 is driven in the reverse direction, assuming that the double-speed light members 52 and 52 are not at the farthest home position, and the photointerrupter 60'b in the home position sensor 60 is activated. This is done by stopping the rotation of the stepping motor 59 if it is turned off.

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. If the copying magnification is the minimum 0°64 times, the stepping motor 59 is is driven in normal rotation for 99 pulses. In addition, in the case of 0.75 times, the stepping motor 59 is driven forward by 69 pulses, and further 0.7
In the case of 8 times, the normal rotation is driven by 59 pulses, and in the case of 0.93 times, 18 pulses are driven in the normal direction. As a result, pinion 5
7 is rotated by a predetermined amount, and both fast light members 52 move toward each other. In this case, since the racks 520 of each light shielding section 52 are formed at equal pitches, the moving distances of both are equal. Due to the mutual proximity of each light shielding member 52,
The light projection area below the site toilet slump arranged on each side is expanded, and the photoreceptor drum 16 is expanded by a length corresponding to each reduction ratio.
The center portion of the image is not exposed, and the other side line portions are exposed.

On the other hand, the photoreceptor drum 16 is uniformly charged over its entire length in the axial direction by a charging corotron 21 as it rotates, and the original 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 imaging lens 15, exposes the charged photoreceptor drum 16, and the exposed portion of the photoreceptor drum 16 has its charge dissipated. , an electrostatic latent image is formed on the photoreceptor drum 16. In this case, since this latent image is a reduced version of the original on the document table 2, each end of the photosensitive drum 16 in the axial direction becomes an outer part wider than the document table 2, and this portion is not exposed. Instead, it becomes charged.

The photoreceptor drum 16 on which the reduced original image has been formed is further rotated, and when it reaches the installation position of the site slump 20, each end of the photoreceptor drum 16 in the axial direction is projected from the site slump 20. The area is exposed to light, and the charge in that area is dissipated. In this case, the light projection area of the site toilet lamp 20 is
2a, and only the axial length portion of the photosensitive drum 16 corresponding to the reduction magnification, that is, the width when the document table 2 is reduced by a predetermined magnification, is exposed by the sight toilet slump 53. This ensures that only each side end of the photoreceptor drum 16 in the axial direction, excluding this portion, is exposed to light, and the charge in that portion is dissipated.

The electrostatic latent image formed on the photoreceptor drum 16 is visualized with toner by a 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, but each side portion of the photoreceptor drum 16 where the original image is not formed undergoes a slump depending on the reduction magnification. The exposure by 55 has dissipated the burden and no toner will adhere to this area.

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 separation corotron 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 In the present invention, a light source is arranged in the direction perpendicular to the direction of movement of the photoconductor to illuminate the side edge of the photoconductor in order to erase unnecessary charges in that area, and a light shielding member that is movable in orthogonal directions and changes the width of the irradiation area of the light source by the movement; means for moving the center position of the width of the light shielding area; driving means for the light shielding member; Since the apparatus includes a detecting means and a means for controlling the driving means according to the detection result of the detecting means, it is possible to completely dissipate unnecessary charges around the original image formed on the photoreceptor. I can do it.

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

[Brief explanation of drawings]

Figure 1 is a perspective view of the electronic copying machine, Figure 2 is its internal configuration, Figure 3 is a plan view of the site toilet slump area, and Figure 4 is a perspective view of the electronic copying machine.
The figure is a longitudinal sectional view, Figure 5 is a partially cutaway perspective view, and Figure 6 is a partially cutaway perspective view.
The figures are a sectional view taken along the line A-A in FIG. 4, FIG. 7 is an exploded perspective view, and FIG. 8 is a flowchart. 16... Photosensitive drum, 52... Light shielding part, 52a
... light shielding plate, 52C ... rack, 53 ... site toilet slump (light l1iX), 56 ... guide rail, 57 ... pinion, 59 ... stepping motor (drive means), 62 ... ...Sliding plate, 63...Connection part.

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 blocking 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, and means for moving the center of the width of the light blocking area. ,
An electronic copying machine characterized by comprising driving means for the light shielding member, means for detecting a reduction ratio, and means for controlling the driving means in accordance with a detection result of the detecting 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 each of the pair of light shielding members has a rack that engages with one pinion 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 is arranged in each direction and a light source is arranged in each side 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 direction of movement, and that change the irradiation area of the light source on each side edge of the photoreceptor by each movement, and move the center of the width of the light shielding area. An electronic copying machine comprising: means for driving the light shielding member; and means for driving the light shielding member. 12. The electronic copying machine according to claim 1, 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 with respect 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. The light shielding member is supported by a support member paired with a support member of the charging means for the photoreceptor.
The electronic copying machine according to item 2.