JPS59195256A - Copying machine - Google Patents

Abstract

PURPOSE:To eliminate the electrostatic charge of an unnecessary charged area corresponding to continuous variation in magnification by using a light emission, source, optical lens, and light irradiation width varying means which are varied in relative position in combination, and varying the irradiation width of exposure light continuously. CONSTITUTION:An original is mounted on an original copying surface 3 and a photosensitive drum 1 is exposed thereto through a projection lens 4 by the light emission of the illumination light source. The original copying surface 3 and projection lens 4 is shifted in relative position to the photosensitive drum 1 according to reduction magnification as shown by (d) and (d'), and (c) and (c') respectively. Unnecessary charged areas x1 and x2 corresponding to them area irradiated with light from the light emission light source and an optical lens 6 which are shifted in position continuously in a housing 9, eliminating charges. Thus, continuous switching of magnification of variable power is realized and the charge of the unnecessary charged area is eliminated.

Description

[Detailed description of the invention] Technical fields> The present invention relates to a copying machine.

<Prior art> In a variable magnification copying machine, when copying an original image at a reduced magnification, the entire photosensitive drum is an effective copying area, so the exposed area of the original image is smaller than the area of the effective copying area. Become. Since charging is performed over the entire effective copy area, when copying is performed at a reduced magnification, a charged area remains outside the original image area.

Therefore, if development is performed in such a state, charged areas other than the original image area will be developed, so to avoid this, generally the charges in the charged areas other than the original image area are removed. Conventionally, a specific light source (lamp) is turned on for the portion of the photoreceptor surface of the photoreceptor drum in the direction of rotational movement, that is, the portion before and after the effective copying area, to uniformly illuminate the area where the charge is to be erased. Furthermore, a predetermined light source of a plurality of light sources provided in advance is turned on to irradiate only a predetermined head portion of the photoreceptor surface of the photoreceptor drum along the rotational movement direction with light according to each magnification ratio. The desired charge erasure was achieved.

By the way, with the recent improvements in the functionality of variable-magnification type copying machines, there has been a demand for continuous switching instead of gradual switching of copy magnification, and in order to meet such demands, the conventional method described above is It has become impossible to satisfactorily erase charges in areas other than the original image area.

<Purpose of the Invention> Therefore, the present invention makes it possible to erase unnecessary charged areas other than the original image area of a photoreceptor, which can correspond to continuous switching of copying magnification instead of stepwise switching in a variable-magnification type copying machine. The purpose is to provide a copying machine with the following features.

<Example> The configuration of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram of an exposure system for a copying machine according to an embodiment of the present invention.

In the figure, l is a photosensitive drum, and the photosensitive drum l
rotates around a rotating shaft 2 that passes through its center, and undergoes desired processes such as charging, exposure, development, etc. It is assumed that the surface of the photosensitive drum 1 is currently charged and is in the stage of exposing an original image.

The copying machine of this embodiment has variable magnification, and in the case of equal magnification, the original image is exposed over the entire area of the photosensitive drum 1 (indicated by X). Since there is no unnecessary charged area in the image, the image is directly transferred to the developing process.

Next, the case of making a reduced copy of an original will be described.

A document is placed on the document copying surface 3, and is exposed onto the photosensitive drum 1 through the projection lens 4 by illumination light # (not shown). The original copying surface 3 and the projection lens 4 change their relative positions with respect to the photosensitive drum 1 according to the reduction magnification. Two different reduction magnifications will be described below.

+1+ Copy size ■ Original copy surface 3 is at position d7 Projection lens 4 is at position C,
The reduced original image is assumed to be exposed onto the photosensitive drum 1 as shown by the solid line.

Therefore, the unexposed portions of the reduced original image on the photosensitive drum 1 are XI at both ends of the photosensitive drum 1.
The area becomes the area shown by (hereinafter referred to as unnecessary charging area P).

In this embodiment, a surface emitting light #5 and an optical lens 6 are provided to irradiate the unnecessary charged area P with light in order to erase the charge on the unnecessary charged area P. The surface emitting light source 5 and the optical lens 6 are designed to be vertically movable with respect to the photosensitive drum 1 (this structure will be described later), and are located at positions a1 and b, respectively. The irradiation width of the light emitted from the surface emitting light source 5 is changed by the optical lens 6, and the unnecessary charged area P is irradiated (
The surface emitting light source 5 emits non-uniform light in consideration of the characteristics of the optical lens 6 and the like. ). In this way, the charges in the unnecessary charged area P are removed. Subsequently, a predetermined copying operation is carried out (according to known technology).

(2) Copy size The original copying surface 3 and the projection lens 4 are moved to position d' and position C', respectively, and the reduced original image is exposed onto the photosensitive drum 1 as shown by the broken line. shall be carried out.

Therefore, the unexposed portions of the reduced original image on the photosensitive drum 1 become areas indicated by X2 at both ends of the photosensitive drum 1 (hereinafter referred to as unnecessary charging areas Q).

Corresponding to the change in the unnecessary charging area from P to Q, the surface emitting light source 5 and the optical lens 6 move, respectively, to the position a'
, changes to position b'.

Subsequently, the charges in the unnecessary charged area Q are erased in the same way as in the case of (1) copy size (2).

The same goes for the following steps.

As shown in FIG. 2, the surface emitting light source 5 and the optical lens 6 are installed inside the housing 9 (a, a').

b, b' correspond to the above explanation. ). The surface emitting light source 5 includes a lamp 7 and a diffusion filter 8 that diffuses the light emitted from the lamp 7. Further, a movable shutter 10 is attached to the optical lens 6 for correcting the amount of light according to the distance from the photosensitive drum 1.

Within this housing 9, the positions of the surface emitting light source 5 and the optical lens 6 can be changed steplessly.

Incidentally, uneven distribution of the scene accompanying the use of the optical lens 6 can be corrected by adjusting the light emission distribution of the surface emitting light source 5 or by adding a light distribution correction plate or the like to the diffusion filter 8.
Exposure for charge erasing can be made uniform in two directions of the rotation axis of the photosensitive drum 1, thereby eliminating uneven charge erasure or partial light fatigue of the photoreceptor on the photosensitive drum 1.

In the above embodiment, both the surface emitting light source 5 and the optical lens 6 are moved, but those skilled in the art will easily think of moving only one of them. Furthermore, as described above, it is conceivable that the shutter 10 is not directly attached to the optical lens 6 but fixed to, for example, the open end of the housing 9 to adjust the amount of light. Further, the light amount can be easily adjusted by changing the voltage of the lamp 7.

Next, the shutter 10 may be replaced with a slit or the like.

Incidentally, the static elimination method of the present invention is not limited to the field related to copying machines, but is also applicable to facsimile machines, printers, and other electronic devices that use an electrostatic latent image creation method, such as those having a narrow line printer, It can be applied as appropriate to devices where the scanning width is made smaller and unnecessary areas are subjected to photostatic charge removal (monochromatic light may be used), and the line scanning time can be shortened in a way that is typical of such electronic devices. It becomes possible.

Effect> As described above, according to the present invention, in a variable magnification type copying machine,
By combining a light emitting light source whose relative position can be changed and a light irradiation width variable means such as an optical lens, it is possible to steplessly change the irradiation width of the exposure light, which is sufficient for continuous switching of magnification ratios, making it practical. It is true.

[Brief explanation of the drawing]

FIG. 1 is a structural diagram of an exposure system for a copying machine according to an embodiment of the present invention, and FIG. 2 is a structural diagram of a charge erasing portion of the exposure system for a copying machine according to an embodiment of the present invention. 1. Photosensitive drum, 2. Rotating shaft, 3. Original copying surface,
4... Projection lens, 5... Surface emitting light source, 6... Optical lens, 7... Lamp, 8 - Diffusion filter, 9...
・・Casing, 10・・Shack-0

Claims (1)

[Scope of Claims] 1. A light emitting light source whose relative position can be changed and a light irradiation width variable means which can change the light irradiation width of the light emitting light source to irradiate light onto an unnecessary charged area on a photoreceptor, and to apply light to the charged area. 1. A copying machine comprising an erasing means for erasing electric charges. 2. The copying machine according to claim 1, wherein the light emitting light source is a surface emitting light source. 3. The copying machine according to claim 1, wherein the light irradiation width variable means is a lens. 4. A light emitting light source whose relative position can be changed, a light irradiation width variable means that can change the light irradiation width of the light emitting light source, and a light amount adjustment means that adjusts the light amount of the light emitting light source, to direct light onto unnecessary charged areas on the photoreceptor. A copying machine comprising an erasing means for irradiating and erasing the charge in the charged area. 5. The copying machine according to claim 4, wherein the light amount adjusting means is a slit. 6. The copying machine according to claim 4, wherein the light amount adjusting means is a shutter.