JPS5855370Y2 - Full exposure device for electrophotographic copying machine - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a full-surface exposure device for an electrophotographic copying machine.

Generally, a full-surface exposure device of an electrophotographic copying machine uses a reflecting mirror whose reflecting surface is a hyperboloid, a paraboloid, or a combination thereof.

Although these reflectors function effectively in accordance with various lighting conditions, they have the disadvantage of poor lighting efficiency.

For example, in a full-surface exposure apparatus using a parabolic reflector 1 as shown in FIG. 1, the light in the diagonally lined portion does not participate in the exposure action, and therefore has poor irradiation efficiency.

In FIG. 1, numeral 2 indicates a light source, numeral 3 indicates an object to be copied, and numeral 4 indicates a regular reflection limit line.

The specular reflection limit line has the following meaning.

In other words, when illuminating an object to be copied, the illumination light itself from the illumination light source and the reflecting mirror equipped to the light source illuminates the imaging lens due to the mirror effect of the surface of the object to be copied or the glass surface for placing the document. There is a development in which the light passes through and reaches the photosensitive surface as it is, and this becomes a ghost or flare that impairs the original projection of the object.

The critical line in which this phenomenon occurs is called the specular reflection limit line.

The specular reflection limit line mentioned above is determined by the angle connecting the most side of the effective illumination range of the object to be copied and the installation position of the imaging lens, and if the light source is placed within this limit line, the above-mentioned phenomenon will occur. becomes noticeable.

Therefore, it has been proposed to place the light source and the reflector outside the specular reflection limit line mentioned above, but 7.
As shown in the figure, the light in the area indicated by the dashed line, for example, the light irradiated towards parts such as the housing, is reflected by the parts, causing the parts to act like a light source. In this state, if the light is reflected by the object to be copied or the glass for placing the document, a new problem arises in that it causes ghost or flare.

SUMMARY OF THE INVENTION An object of the present invention is to provide a full-surface exposure device for an electrophotographic copying machine that can eliminate the above-mentioned drawbacks.

The present invention will be explained below based on the embodiment shown in FIG.

In FIG. 2, the reference numeral 6 indicates the object to be copied, the reference numeral 7 indicates the light source, the reference numeral B indicates the elliptical reflecting mirror, the reference numeral 5 indicates the second focal point, and the reference numeral 9 indicates the specular reflection. It shows the limit line.

A condensing lens and a photoreceptor (not shown) are arranged at a lower position in the figure.

The elliptical reflecting mirror 8 has a first focal point that is far from the object 6 and a second focal point that is close to the object 6, and the first focal point is located outside the regular reflection limit line 9. and the second focal point is located near the specular reflection limit line 9.

A light source 7 is arranged at the first focal point of the elliptical reflecting mirror 8.

The opening 8a of the elliptical reflector 8 is arranged so that the direct light from the light source 7 illuminates almost only the object 6 that requires illumination.
Further, the reflected light from the elliptical reflecting mirror 8 that receives the light from the light source 7 is also formed so as to illuminate almost only the object 6 that requires illumination.

In the elliptical reflector 8, there is a law that when a ray of light emitted from the first focus is reflected by the reflector, the reflected light always passes through the second focus, so the reflected light from the ellipse reflector 8 is Proceed as indicated by the dashed line.

Note that a part of the elliptical reflecting mirror 8 may have another shape due to space limitations.

For example, if the light source 7 is too large and the elliptical reflector 8 is a perfect ellipse, it is impossible to place the light source 7 at the first focal point. good.

Further, by making the reflecting surface of the elliptical reflecting mirror 8 a diffusing surface, it is possible to reduce the unevenness of illuminance.

According to the present invention, both the direct light from the light source and the reflected light from the elliptical reflector illuminate almost only the object to be copied that requires illumination, resulting in extremely high illumination efficiency.

In addition, since the light from the light source and reflecting mirror illuminates only the object to be copied that requires illumination, even if the above-mentioned illumination member is placed outside the specular reflection limit line, parts such as the housing cannot be replaced. In this case, the portion that becomes the secondary light source is not irradiated with light, and therefore ghosts and flares can be prevented from occurring.

[Brief explanation of the drawing]

FIG. 1 is a layout diagram showing one embodiment of a conventional full-surface exposure device for an electrophotographic copying machine, and FIG. 2 is a layout diagram showing a full-surface exposure device for an electrophotographic copying machine according to the present invention. 6...Object to be copied, 7...Light source, 8...Elliptical reflector, 9...Specular reflection limit line.

Claims (1)

[Scope of utility model registration request] When the focal point of the elliptical reflector that is far from the object to be copied is the first focal point and the focal point closer to the object is the second focal point, the first focal point is located outside the specular reflection limit line and the second focal point is outside the specular reflection limit line. Arrange the elliptical reflector so that it is located near the line, and place the light source at the first focus of this ellipse reflector so that the direct light from the light source illuminates almost only the object to be copied, and from the ellipse reflector. 1. A full-surface exposure device for an electrophotographic copying machine, characterized in that an opening of an elliptical reflector is configured so that the reflected light illuminates only the object to be copied.