JPH0453639Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to an optical system drive device for an electrophotographic copying machine that forms a copied image by an electrophotographic process.

(Prior Art) An electrophotographic copying machine exposes a document on a document table to light using an optical system to form an electrostatic latent image corresponding to the document image on a photoreceptor, and then prints the electrostatic latent image with toner. A copy image is obtained by developing and transferring the toner image to transfer paper.

An optical system that exposes an image of an original onto a photoreceptor is moved relative to the original so as to expose the entire surface of the original. One of the methods for relatively moving the optical system and the document is to fix the document table on which the document is placed and move the optical system along the document table.

In this method of moving the optical system, it is necessary to scan the light source for exposing the original image along the entire area of the original table and then return it to the scanning start position. In addition, in order to keep the length of the optical path constant from the document on the document table to the photoconductor, a reflector that guides the light reflected by the document to the photoconductor is configured separately from the light source. , the reflecting mirror is moved back and forth at 1/2 of the moving speed of the light source. For this reason, focusing on the fact that the moving speed of the light source and the moving speed of the reflecting mirror can be easily set to 2:1, a method has been adopted in which the light source and the reflecting mirror are moved using wires.

In this case, in order to move the optical system parallel to the exposure scanning direction, two wires are attached to each end of the optical system in a direction perpendicular to the exposure scanning direction, and each wire is moved at a constant speed in the exposure scanning direction. must be moved. In order to move each wire at a constant speed,
As shown in FIG. 4, a pair of drive pulleys 92 and 92 are attached to one drive shaft 91, and each wire 9
3 and 93 around each drive pulley 92 and 92 is performed. The drive shaft 91 is a motor 94
The drive pulleys 92 and 92 can be rotated in the forward and reverse directions.
rotates forward and backward, moving each wire 93 in the exposure scanning direction and in a direction opposite to this direction. The optical system is then moved in the exposure scanning direction and in the opposite direction by being pulled by the wires 93 and 93.

Each wire 93 and 93 attached to the optical system
extends in the exposure scanning direction, is wound around each drive pulley 92, and extends in the opposite direction to the exposure scanning direction. When each drive pulley 92 and 92 is rotated normally in the direction shown by arrow E and each wire 93 and 93 moves in the direction shown by arrow F to pull the optical system in the exposure scanning direction, as a reaction of the pulling force, A force is applied in a direction opposite to the moving direction, and a force is applied to each drive pulley 92 in the direction in which the wound wires 93 and 93 extend (in a direction opposite to the exposure scanning direction). Therefore, each of the drive pulleys 92 and 92 may be pulled by the wires 93 and 93, and the drive shaft 91 may be bent. When the drive shaft 91 is bent, the moving speeds of the wires 93 and 93 become uneven.
This unevenness in the moving speed leads to unevenness in the moving speed of the optical system, causing blur in the original image exposed on the photoreceptor. In order to prevent deflection of the drive shaft 91,
If the diameter of the drive shaft 91 is increased, the motor 94 must be rotated at high speed in order to move the optical system at high speed, making it difficult to realize high-speed movement of the optical system.

(Problems to be Solved by the Invention) The present invention is intended to solve the above-mentioned conventional problems, and its purpose is to prevent deflection of the drive shaft, which causes unevenness in the moving speed of the optical system. It is an object of the present invention to provide an optical system drive device for an electrophotographic copying machine that is free from fear.

(Means for Solving the Problems) The present invention is an electrophotographic copying system in which an optical system is moved along a document tray in order to expose the image of the document placed on the document tray onto a photoreceptor. This is the optical system driving device of the machine, and includes a pair of drive pulleys attached to a single drive shaft that is arranged perpendicular to the exposure scanning direction and driven to rotate, and a pair of drive pulleys attached to a drive shaft that is rotated and driven in the exposure scanning direction. attached at positions facing the parallel auxiliary pulleys and each drive pulley of the optical system, and extending from the optical system in the exposure scanning direction;
It is wound around each of the driving pulleys and extends in the exposure scanning direction, further wound around each of the auxiliary pulleys and extended in the anti-exposure scanning direction, and again wound around each of the driving pulleys and extended in the anti-exposure scanning direction. and a pair of wires extending out, thereby achieving the above object.

(Example) The present invention will be described below with reference to embodiments.

The optical system drive device of the present invention is used, for example, in an electrophotographic copying machine shown in FIG. The electrophotographic copying machine has an optical system 20 in the upper part and a photosensitive drum 10 in the substantially central part of the lower part. The top surface of the machine is a document placement table 11 made of contact glass or the like, and the document placed on the document placement table 11 is exposed by an optical system 20 that moves in the exposure scanning direction shown by arrow A. , the original image is guided onto the photosensitive drum 10.

The optical system 20 includes a light source 21 that projects light toward an upper document placement table 11, and a first light source that reflects light reflected by the document on the document placement table 11 at a substantially right angle.
A reflecting mirror 22, a second reflecting mirror 23 and a third reflecting mirror 24 that invert the light reflected by the first reflecting mirror 22, and the light reflected by the third reflecting mirror 24 is reflected by the lens 2.
and a fourth reflecting mirror 25 that guides the light that has passed through the photoreceptor drum 6 onto the photoreceptor drum 10. The light source 20 and the first reflecting mirror 22 move together in the exposure scanning direction shown by arrow A, and the second reflecting mirror 23 and the third reflecting mirror 24 also move together in the exposure scanning direction. Move to. The lens 26 and the fourth reflecting mirror 25 are fixed to the aircraft body.

The light source 21 and the first reflecting mirror 22 are movable over substantially the entire area of the document table 11, and the second reflecting mirror 23 and the third reflecting mirror 24
moves at half the speed of movement of the light source 21 and the first reflecting mirror 22. Therefore, the second reflecting mirror 2
3 and the third reflecting mirror 24 are the light source 21
and 1/2 of the moving distance of the first reflecting mirror 22,
The optical path length from the document on the document table to the photosensitive drum 10 is always constant. After the light source 21 and the first reflecting mirror 22 have moved over the entire area of the document table 11, they return to the exposure scanning start position.
The second reflecting mirror 23 and the third reflecting mirror 24 also move to the approximate center of the body, and then return to the exposure scanning start position.

The photosensitive drum 10 is rotatable in the direction shown by arrow B, and a charging device 12 and a developing device 1 are arranged around it from above to the downstream side in the direction of rotation.
3. A transfer device 14, a separation device 15, and a cleaning device 16 are arranged in this order.

After the surface of the photoreceptor drum 10 is uniformly charged by a charging device 12, an original image is exposed by an upper optical system 20 to form an electrostatic latent image corresponding to the original image. The electrostatic latent image is developed with toner by a developing device 13, and the toner image is transferred to a transfer paper by a transfer device 14. The transfer paper onto which the toner image has been transferred is transferred to the photoreceptor drum 10 by a separating device 15.
The toner image is separated from the transfer paper, and after being fixed on the transfer paper by the fixing device 17, it is discharged outside the machine. After the toner image has been transferred to the photosensitive drum 10, residual toner and the like are removed by a cleaning device 16.

The optical system driving device of the present invention, as shown in FIG.
And the first reflecting mirror 22, the second reflecting mirror 23, and the third reflecting mirror 24 are integrally connected to each other as indicated by the arrow A.
It is parallelly moved in the exposure scanning direction shown by and in the opposite direction (hereinafter referred to as anti-exposure scanning direction).

Each wire 31 and 31 connects each drive pulley 32 and 32 vertically arranged near the end position of the exposure scan of the light source 21 and each drive pulley 32 and 32.
Each auxiliary pulley 33 is arranged in parallel in the exposure scanning direction and has the same diameter as each drive pulley 32 and 32 and is vertical.
and 33, fixed pulleys 34 and 34 arranged vertically near the exposure scanning start position, and respective fixed pulleys 34 and 34 in a direction perpendicular to the exposure scanning direction of the integrated second and third reflecting mirrors 23 and 33, respectively. It is wound around each moving pulley 35, which is horizontally attached to the end.

As shown in FIG. 3, the pair of drive pulleys 32 and 32 are attached to each end of a drive shaft 36 that is supported by a pair of bearings 37 and 37 so as to be orthogonal to the exposure scanning direction. ing. A gear 38 is externally fitted and fixed to the drive shaft 36, and the gear 38 meshes with a gear 39a attached to the output shaft of a motor 39. Therefore, the drive shaft 36 rotates forward and backward as the motor 39 rotates forward and backward.
A pair of auxiliary pulleys 33 and 33 are rotatably supported on the exposure scanning direction side of each drive pulley 32 and 32.

Each wire 31 has one end 31a fixed to an appropriate position on the machine body further in the exposure scanning direction than the end position of the exposure scanning of the light source 21, and the other end 31b fixed to the second reflecting mirror 23 and the third reflecting mirror. It is fixed at an appropriate position on the machine body on the side opposite to the exposure scanning direction from the exposure scanning start position of No. 24. Each wire 31 extends from one end 31a in the anti-exposure scanning direction, and is wound around each movable pulley 35 attached to the second and third reflecting mirrors 23 and 24, which are integrated, for half a circumference, so that the wires 31 are exposed. It extends in the scanning direction. Each end of the integrated light source 21 and first reflecting mirror 22 in a direction perpendicular to the exposure scanning direction is locked to a portion of each wire 31 extending from each moving pulley 35 .

Each wire 31 connects the light source 21 and the first reflecting mirror 2.
2, it further extends in the exposure scanning direction, is wound around the drive pulley 32 a plurality of times, and further extends in the exposure scanning direction. Each drive pulley 32
Each wire 31 extending in this direction is wound around each auxiliary pulley 33 over half a circumference, extends in the anti-exposure scanning direction, and is wound around the drive pulley 32 several times again. The wire 31 wound around the drive pulley 32 extends in the anti-exposure scanning direction.

A wire 31 extending from the driving pulley 32 in the opposite exposure scanning direction is wound around a fixed pulley 34 disposed near the exposure scanning start position over half a circumference, and extends in the exposure scanning direction, and the wire 31 extends in the exposure scanning direction. and the aforementioned moving pulley 3 attached to the third reflecting mirror 24.
5, it is again wrapped around half the circumference and extends in the anti-exposure scanning direction. The end portion 31b extending in this direction is fixed to a suitable position on the body.

In an electrophotographic copying machine having an optical system drive device configured as described above, an image of the original is exposed to light while the original is placed on the original placing table 11. That is,
When a predetermined switch is operated to perform a copying operation, the drive shaft 36 is rotated in the direction shown by arrow C in FIG. As the drive shaft 36 rotates, the wires 31 and 31 move synchronously in the direction shown by arrow D in FIG. 2, pulling the integrated light source 21 and first reflecting mirror 22 in the exposure scanning direction. . Thereby, the light source 21 and the first reflecting mirror 22 are moved in parallel in the exposure scanning direction at the same speed as the moving speed of the wires 31 and 31. Since the scanning direction side ends 31a and 31a of the wires 31 and 31 are fixed, the movement of the wires 31 and 31 in the direction of arrow D causes the wires 31 and 31 to
1a and 31a, and the moving pulleys 35 and 35 around which the wires 31 and 31 are wound are pulled in the exposure scanning direction. This causes the second reflecting mirror 23 and the third reflecting mirror 24 to move in parallel in the exposure scanning direction. The moving speed of the moving pulleys 35 and 35 (therefore, the second reflecting mirror 23 and the third reflecting mirror 2
4) is 1/2 of the moving speed of the wires 31 and 31.

In this way, the light source 21 and the first reflecting mirror 22
Then, the second reflecting mirror 23 and the third reflecting mirror 24 are moved in the exposure scanning direction so that the speed ratio thereof is 2:1. During this movement, the original on the original placing table 11 is exposed to light projected from the light source 21, and the reflected light is reflected by the first reflecting mirror 22,
The electrostatic latent image is projected onto the photosensitive drum 10 by the second reflecting mirror 23, the third reflecting mirror 24, and the fourth reflecting mirror 25, and an electrostatic latent image is formed on the photosensitive drum 10. The electrostatic latent image is developed with toner as in a normal electrophotographic process, and the toner image is transferred to transfer paper to obtain a copy image.

When the light source 21 and the first reflecting mirror 22 reach the exposure scan end position, the drive shaft 36 is rotated in the direction opposite to the arrow C, and the wires 31 and 31 are synchronously reversed. This allows the light source 21 and the first
The reflecting mirror 22 is translated in the anti-exposure scanning direction, and the movable pulleys 35 and 35 may be pulled in the anti-exposure scanning direction, and the second and third reflecting mirrors 23 and 24 are also translated in that direction.

The wires 31 and 31 wound around the drive pulleys 32 and 32 are connected to each drive pulley 32 and 32.
They extend in opposite directions at the top, and also extend in opposite directions at the bottom. Therefore, as the drive pulley 32 rotates, the wire 31 moves, and a reaction force in the opposite direction to the direction of movement is applied to the wire 3.
1, the force applied to the drive pulley 32 is
The upper and lower wires 31 extending in opposite directions cancel each other out and balance each other. Therefore, there is no risk that the drive pulleys 32 and 32 will be pulled by the respective wires 31 and 31, and there is no risk that the drive shaft 31 will bend. Since the wires 31 extend in opposite directions at the upper and lower portions of the drive pulley 36, there is no risk of moment acting on the drive pulley 36.

(Effect of the invention) In this way, the optical system driving device of the invention winds the wire for moving the optical system around the driving pulley and the auxiliary pulley arranged in parallel in the exposure scanning direction of the driving pulley, and drives the optical system. Since no force is applied to the pulley in the exposure scanning direction or the anti-exposure scanning direction, no force is applied to the end of the drive shaft to which each drive pulley is attached, and there is no risk of the drive shaft being bent. Furthermore, there is no risk of moment acting on the drive pulley itself. As a result, the optical system is moved at a constant speed.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of an electrophotographic copying machine, FIG. 2 is a schematic diagram showing an example of an optical system drive device of the present invention, and FIG.
The figure is a perspective view of the main parts thereof, and FIG. 4 is a perspective view of the main parts of a conventional optical system drive device. 21... Light source, 22... First reflecting mirror, 23...
Second reflecting mirror, 24...Third reflecting mirror, 31...Wire, 32...Drive pulley, 33...Auxiliary pulley,
36... Drive shaft.

Claims (1)

[Scope of Claim for Utility Model Registration] An optical system drive device for an electrophotographic copying machine that moves an optical system along a document platform in order to expose an image of a document placed on the document platform onto a photoreceptor. A pair of drive pulleys are arranged perpendicularly to the exposure scanning direction and are attached to one drive shaft that is rotationally driven, and auxiliary pulleys are respectively arranged in parallel with the drive pulleys in the exposure scanning direction. and are respectively attached to positions facing each of the drive pulleys of the optical system, extend from the optical system in the exposure scanning direction, are wound around each of the drive pulleys and extend in the exposure scanning direction, and are further attached to each of the auxiliary pulleys. An optical system drive device for an electrophotographic copying machine, comprising: a pair of wires that are wound around each drive pulley and extend in the anti-exposure scanning direction, and are again wound around each drive pulley and extend in the anti-exposure scanning direction.