JPS5823055A - Optical system - Google Patents

Abstract

PURPOSE:To facilitate the fine adjustment of an imaging position along a principal light beam according to variation in the focal length of a lens by providing a reflecting mirror so that the angle of the principal light beam of an optical system to the bisector of the angle 2theta formed between two reflective surfaces is (pi/2)-2theta. CONSTITUTION:An image on an original on platen glass 1 is reflected by a reflecting mirror 2 and further reflected by a plane mirror arranged along the perpendicular surface, and then guided to the surface of a drumlike photoreceptor through a lens, but a principal light beam 14 from said original is made incident to a lower reflecting plate 7 at a 22.5 deg. angle of incidence and reflected upwardly to an upper reflecting plate 8 at a 45 deg. angle to the horizontal surface and then its reflected principal light beam 15 is reflected by a reflecting plate 8 to travel to the lens as a horizontal principal light beam 16. In this case, if the lens varies in focal length slightly from a set value, a bracket 11 is moved slightly to the surface of an optical frame 12 having a 45 deg. angle to the horizontal surface to finely adjust the optical lengths of the principal light beams 14-16.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an optical system that forms an image of a document on a platen glass of a copying machine onto a photoreceptor or the like.

A lens is always inserted in the optical path of an optical system, but even if the lens is made of the same material and has a curved surface according to specifications, the focal length may differ due to slight changes in the composition of the material. come.

In an optical system where the distance between the subject and the image plane is constant, if the focal length of the lens is always constant, the lens can be placed at a constant position, but for the reasons mentioned above, the lens If the focal length differs even slightly, it is necessary to fine-tune the position of the subject and/or the imaging plane, or the position of the lens.
The image position may shift along the image plane,
The adjustment was extremely complicated.

The present invention relates to an improvement of an optical system that overcomes these difficulties. It is characterized in that the reflecting mirror is arranged so that the angle formed by the principal ray of the optical system with respect to the bisector of the angle 2θ formed by the reflecting surface is -20, and its purpose is to: The object of the present invention is to provide an optical system that can easily finely adjust the imaging position along the principal ray in response to a shift in the focal length of a lens.

Since the present invention is configured as described above, after the principal ray before incidence is reflected by one of the two reflecting surfaces, the bisector of the angle 2θ formed by the two reflecting surfaces and is incident on the other reflective surface at an angle of incidence that is the same as the angle of reflection on the one reflective surface, resulting in an angle of incidence that is the same as the angle of incidence on the one reflective surface. reflected at a reflection angle of

Therefore, in the present invention, when the reflecting mirror is moved along the bisector of the angle formed by the two reflecting surfaces, the relative Since the optical path length of the principal ray changes while the angular relationship remains completely unchanged, the imaging position along the principal ray can be easily finely adjusted in response to a slight change in the focal length of the lens.

The embodiments shown in FIGS. 1 to 3 in which the present invention is applied to the optical system of a copying machine will be described below.

3 is a platen glass, on which a document (not shown) is placed.

Further, a reflecting mirror 2 having a structure as shown in detail later is disposed below the platen glass 1, and the image of the document on the platen glass 1 illuminated by a lamp (not shown) is reflected by the reflecting mirror 2. 2, is further reflected by a plane mirror 3 along a vertical plane, passes through a lens 4, and then is reflected by a plane mirror 5.
The light is reflected downward and an image is formed on the surface of the drum-shaped photoreceptor 60.

Further, the reflecting mirror 2 has two upper and lower reflecting plates 7.8, and a metal fitting 9 with both ends of the reflecting plates 7.8 forming an angle of 45° to each other.
The above-mentioned two holding plates 7.8 are held so that the bisector 13 of the angle formed by the pair of left and right holding plates 10 fixedly supported by the reflecting plates 7.8 forms an angle of 45° with respect to the horizontal plane. It consists of a bracket 11 for attaching the plate 10 to an optical frame 12.

As shown in FIG. 3, the bracket 11
The mounting surface of the optical frame 12 and the optical frame 12 is also a surface that forms an angle of 45° with respect to the horizontal plane, that is, the two reflecting plates 7.8
The angle 45' formed by the angle 45' can be finely adjusted by a small distance along a plane parallel to the central plane 13.

Since the embodiment shown in FIGS. 1 to 3 is constructed as described above, the chief ray 14 from the original on the platen glass 1 is directed vertically downward, and the beam rays are 22.5
The principal ray 15 of the reflected light enters the upper reflector 8 at an angle of incidence of 22.5 degrees and is reflected at an upward angle of 45 degrees to the horizontal plane toward the upper reflector 8. Since the principal ray 16 is incident at an angle and then reflected, the principal ray 16 reflected by the upper reflector 8 is directed in the horizontal direction and reaches the surface of the drum-shaped photoreceptor 6 via the plane mirror 3, lens 4, and plane mirror 5. .

In this case, the focal length of the lens 4 is slightly deviated from the set value, and in order to slightly fine-tune the optical path length of the principal ray 14, 15, 16, it is necessary to set the focal length of the lens 4 at an angle of 45° to the horizontal plane. platen against the surface of the frame 12)
All you have to do is move II slightly.

Although FIGS. 4 and 5 show the positional relationship of the principal rays 14.16 of the above embodiment in an inverted vertical relationship, the platen II is moved upward so as to be away from the intersection of the reflectors 7.8. (to the right in Figures 4 and 5), the relationship between the principal rays 14 and I5.16 and their incidence and reflection on the reflector 7.8 remains completely unchanged as shown in Figure 5. Also, with respect to the movement tY of the bracket 11, the imaging position P with respect to the photoreceptor 6 moves to the front side by 4 Y tan 22.5 degrees.

Conversely, if you move the platen +1 downward by Y, the imaging position @P will be 4 Y tan 22.5 degrees to the photoconductor 6.
can be moved to the depth side.

In this case, the angle of incidence of the incident principal ray 14 on the reflecting plate 7 does not change at all, and its reflected principal ray 15 is parallel, and the angle of incidence of the principal ray 15 on the reflecting plate 8 does not change at all, so the surface of the photoreceptor 6 There is no displacement of the chief ray 16 along.

Furthermore, even if the reflecting mirror 2 rotates about the intersection line of the extended plane along the reflecting plate 7.8, the relative angular relationship between the incident principal ray 14 and the reflected principal ray 16 remains completely unchanged. There is no vertical deviation to the surface of 6.

In the embodiments described above, the present invention is applied to a copying machine, but the present invention can of course be applied to other optical devices.

[Brief explanation of drawings]

FIG. 1 is a perspective view of an embodiment of the optical system according to the present invention applied to a copying machine, FIG. 2 is a perspective view of the embodiment, and FIG.
The figure is a side view thereof, and FIGS. 4 and 5 are explanatory diagrams showing the operation of the same embodiment. DESCRIPTION OF SYMBOLS 1... Platen glass, 2... Reflecting mirror, 3... Plane mirror, 4... Lens, 5... Plane mirror, 6... Drum-shaped photoreceptor, 7.8... Reflecting plate, 9...Metal fittings, 10
... Holding plate, 11... Bracket, 12... Optical frame, 13... Bisector line, 14.15.1
6... Chief ray. Representative and embedded patent attorney: Nozomi Ehara (1 person)

Claims (1)

[Claims] In an optical system incorporating a set of reflecting mirrors in which the relative positional relationship of the two reflecting surfaces is fixed, the angle formed by the principal ray of the optical system with respect to the bisector of the angle formed by the two reflecting surfaces is 100-2
An optical system characterized in that the reflecting mirrors are arranged so that the angle becomes 0.