JPH0121296Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an image illuminance adjustment device that can equalize the illuminance of an image.

In copying machines, etc., a dimming plate is generally used as a method to equalize the illuminance on the imaging plane even if there is uneven brightness on the subject surface or the light intensity decreases around the lens. Methods have been attempted to do this, but their implementation is accompanied by various difficulties.

The present invention makes it possible to easily equalize the illuminance on the imaging plane.

An embodiment in which the present invention is applied to an electrophotographic printing device will be described below.

First, I will explain the basic configuration of this device.
A photosensitive material that is a long sheet-like member, a feeding means for feeding the photosensitive material by a predetermined dimension at a predetermined timing, a cutter means for locally cutting the photosensitive material, and a photosensitive material for cutting the photosensitive material locally. A charging device for uniformly charging a portion of the photosensitive material, an exposing device for exposing an image of a subject on the charged photosensitive material, and a developing device for developing the photosensitive material sent out after exposure.
and separating means for separating the photosensitive materials one by one. Exposure means corresponding to the part of the present invention will be described below with reference to embodiments shown in the drawings.

First, the object 2 illuminated by the lamp 1 is refracted by the reflecting mirrors 3 and 4, and reflected by the lens 5, and the lens 5 forms an image on the photoreceptor on the image forming surface 6. There is. In this case, the reflecting mirrors 3, 4 and lens 5 are all connected to the subject 2.
The optical system is disposed inside an optical system dark box 9 that covers the entire surface with only the entrance light window 7 that lets in the incident light from the lens 5 and the exit light window 8 that allows the exit light from the lens 5 to pass through as openings. Here, the reflecting mirror 4 has a transparent part (i.e., a part not coated for reflection).
4A as shown in FIG. 2, and this transparent portion 4A closes the exit light window 8 of the dark box 9. Therefore, the light from the subject 2 passes through the reflecting mirror 3 and then the reflecting part 4 of the reflecting mirror 4.
B. The light passes through the lens 5, passes through the transparent portion 4A of the reflecting mirror 4, and reaches the photosensitive surface. By adopting a configuration in which the reflecting portion 4B and the transparent portion 4A are integrally provided in one reflecting mirror 4, the inside of the optical system dark box 9 is completely sealed, thereby providing a function such as dust prevention. This reflecting mirror 4 can be easily obtained by performing aluminum vapor deposition to form a normal reflecting mirror only on a part of a sheet of optical glass. Furthermore, since the incident light window 7 is covered with a normal transparent glass 10, the interior of the optical system dark box 9 is completely sealed and dust-proof. Note that 14 is a lid that opens and closes the exit light window.

In addition, a light amount adjusting part 12 printed with an appropriate thickness and spacing is provided on the transparent part 4A of the reflecting mirror 4 so as to block a part 11 of the light flux emitted from the lens 5, and the light rays passing through this part form an image. The illuminance of the imaging plane in range 13 is reduced. Illuminance (brightness) on the image plane 6 occurs due to variations in illuminance above the subject 2 and insufficient peripheral light due to lens characteristics.
We are trying to compensate for the variation in.

FIG. 3a is an optical characteristic diagram of the image illuminance adjusting device when the light amount is not adjusted, and FIG. 3b is an optical characteristic diagram of the same device when the light amount is adjusted. In Figures 3a and 3b, if the amount of light passing through the lens 5 is not adjusted, the light amount distribution on the imaging plane is a in Figure 3a.
It is expressed like a line, and on the optical axis of the lens 5 c
This causes a very large difference in the amount of light between the peripheral area and the peripheral area, resulting in uneven copying. Therefore, if the allowable difference in light amount is H, the usable imaging range will be narrow, A-A'.

On the other hand, when the light amount adjustment section according to the present invention is provided, the light amount distribution on the imaging plane is expressed as line b in FIG. 3b, and the imaging range where the difference in light amount is within the tolerance H is It can be widened to B-B'.

As is clear from the above embodiment, the present invention has a structure in which the light amount adjustment section is placed between the lens and the image forming surface, so that the thickness and number of lines printed on the light amount adjustment section can be set to a value greater than the resolution of the copying machine. However, the line of the light amount adjustment section is difficult to see on the imaging plane. Therefore, silk printing for the lines of the light amount adjustment section can sufficiently achieve the purpose, and has the effect of significantly reducing costs compared to the conventional method.

In addition, since this invention uses a reflector and an in-mirror lens, the distance from the subject to the imaging plane can be shortened while maintaining a predetermined optical axis length. Since these are constructed on the same plane and on the same glass, there is no interruption of light by protrusions, and small space can be used effectively.
Since it is possible to simultaneously form a reflective part by aluminum vapor deposition and a light amount adjustment part by silk printing on a sheet of glass, it has the effect of significantly reducing costs.

[Brief explanation of the drawing]

FIG. 1 is a side sectional view of an image illuminance adjustment device according to an embodiment of the present invention, FIG. 2 is a sectional view of a reflecting mirror, and FIG.
FIG. 3a is a light amount distribution diagram of the same device when the light amount is not adjusted, and FIG. 3b is a light amount distribution diagram of the same device when the light amount is adjusted. 1...Lamp, 2...Subject, 3...Reflector,
4...Reflecting mirror, 4A...Transparent part, 4B...Reflecting part, 5...Lens, 12...Light amount adjustment part, 13...
...imaging range.

Claims (1)

[Scope of utility model registration request] A reflector that enters and reflects the light from the subject, an aluminum vapor-deposited reflector that receives and reflects the reflected light from this reflector, and an in-mirror lens that receives the reflected light from this reflector and projects it onto the imaging plane. and a light amount adjusting section which is arranged between the in-mirror lens and the image forming surface and is silk-printed with a plurality of lines having a thickness that adjusts the light amount near the center of the light beam of the in-mirror lens at intervals. and a sealed and dust-proof dark box that houses the reflecting mirror, the reflective part, the in-mirror lens, and the transparent part, and has an exit light window that is covered by the transparent part and an incident light window that is covered with dust-proof glass. An image illuminance adjustment device characterized in that the reflective section and the transparent section are constructed of a single piece of coplanar glass.