JPH0255786B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an optical system of a copying apparatus, and particularly to a copying apparatus characterized by a holding structure for a moving mirror in a moving optical system that performs slit exposure.

(Prior Art) In a copying device, such as an electrophotographic copying device, light from a light source is irradiated onto a document placed on a document table, and the reflected light is passed through an optical system consisting of mirrors and lenses to generate a charged image. Image recording is performed by forming a latent image on the surface of a photoreceptor, developing it, transferring it, and fixing it.

In a typical electrophotographic copying apparatus, an original image is projected onto a moving photoreceptor.

As a method for forming an image on the surface of a photoreceptor that moves in this way, there are usually two methods: a method in which the document table is fixed and the optical system moves, and a method in which the optical system is fixed and the document table is moved.

Examples of the former method include JP-A-48-100119, JP-A-49-99035, and JP-A-52-
There is an exposure apparatus disclosed in Japanese Patent No. 155533 or an exposure apparatus shown in FIG.

Among these exposure apparatuses, the optical systems disclosed in the above-mentioned publications are common. In other words, the light irradiated on the document is sequentially reflected by multiple mirrors and guided to the surface of the photoreceptor via a lens, and the optical path is such that the light travels diagonally to the document table to avoid interference with each other. It is set. Therefore, the space occupied by the optical system, especially its height, had to be increased. An exposure apparatus developed to solve this problem is shown in FIG.

The present invention is directed to the exposure apparatus shown in FIG.

Hereinafter, the prior art will be explained with reference to FIG. 1 and further using FIGS. 2 and 3.

In FIG. 1, 1 is a document, 2 is a transparent document table on which the document 1 is placed, 3 is a document illumination lamp, 4 is a first mirror that receives and reflects the light reflected from the document 1, and 5 is a first mirror.
A second mirror 6 receives the reflected light from the second mirror and reflects it toward a fixed fourth mirror 7 through a lens 8.
A photoreceptor 9 receives the reflected light from the fourth mirror 7 and forms an image on the moving surface.

The original illumination lamp 3 and the first mirror 4 are integrated via a holding member (not shown), and move parallel to the original table 2 at a predetermined speed V. Also, the second mirror 5
is arranged to be inclined so as to be parallel to the first mirror 4, and is held by a holding member 10 (FIG. 2) so that the reflecting surface is at right angles to the third mirror 6,
The first mirror 4 at half the speed of the first mirror 4, 1/4V.
move synchronously in the same direction. Furthermore, the photoreceptor 9 also moves synchronously with the first mirror 4 at the same speed V.
The driving means for each of these members is the same as the means disclosed in the above-mentioned publications and is well known.

2 and 3 show a conventional mirror holding member. FIG. 2 is a side view of the holding portion, and FIG. 3 is a top view thereof. The second mirror 5 and the third mirror 6 are attached to the mirror holding member 1 by means such as screws (not shown).
Fixed to 0. In Figures 2 and 3,
10 is a mirror holding member, 11 is a pulley, 12 is a drive wire that is hung on the pulley 11 and causes the second mirror 5, third mirror 6, and holding member 10 to reciprocate together; 13 is a drive wire on the drive side of the holding member 10 (pulley 11); The guide rail 14 provided on the side) is a guide roller that is provided on the driven side of the holding member 10 and stabilizes the driven end of the holding member 10.

The holding member 10 holding the second mirror 5 and the third mirror is placed parallel to the document table 2 as described above.
This will be done at a speed of 1/2V, which is half the speed of mirror 4.

On the other hand, in modern copying machines that have a large document table 2 that is capable of copying even large-sized originals such as A3, the length of the mirror used in the optical system also depends on the length of the original. It is inevitable that the size will increase as the size of the . Furthermore, in order to meet the demand for higher speeds, it is necessary to increase the acceleration/deceleration, and a large inertial force acts on the holding member each time the mirror is started or stopped. Therefore, as the length of the optical system increases and the speed increases, the inertia force will be concentrated on the drive side of the holding member when the mirror starts and stops, and the rigidity of the drive side will be distributed to the driven side. As a result, the driven side cannot follow the driving side, resulting in vibration and play.

Therefore, conventionally, the holding member 10 is provided with a reinforcing portion having a width shown by a in FIG. 3 on the driving side and gradually narrowing in width toward the driven side. In this structure, the holding member 1 that holds the second mirror 5 and the third mirror 6
0, the original illumination lamp 3 and the
The same can be said of the holding member that holds the mirror 4.

However, it should be noted here that the holding members for the original illumination lamp 3 and the first mirror 4 are not required to be as strict against backlash and vibration characteristics as the holding members for the second mirror 5 and third mirror 6. That's true. The reason for this is that firstly, the width of the first mirror 4 is
The width of the mirror 5 and the third mirror 6 is approximately 1/2, and the weight of the document illumination lamp 3 is also lighter than that of the second mirror 5 and the third mirror 6. It can be mentioned that the influence of the blurring of the second mirror 5 and the third mirror 6 on the image is far greater than the influence of the blurring of the first mirror 4 on the image. Therefore, in the exposure apparatus having the optical system shown in FIG. 1, it is most important to ensure sufficient rigidity of the holding members for the second mirror 5 and the third mirror 6. The reinforcing portion is made by widening the driving side of the holding member 10 to increase the rigidity of the driving side, and elongating the portion that fits into the guide rail 13. This also prevents the second mirror 5 and the third mirror 6 from shaking during reciprocating movement of the optical system.

However, the second mirror 5 and the third mirror 6
As is clear from FIGS. 2 and 3, the holding member 10 is provided with a reinforcing portion projecting rearward from the intersection position of the second mirror 5 and the third mirror 6 on the back side. This is generally to avoid blocking the path of light in an optical system. By the way, the first
In the case of movable optical systems before the optical system shown in the figure was developed, the optical paths were all turned diagonally as shown in the above publications, so it was necessary to arrange an interference member in the optical path. This is because it was considered impossible. In addition, there are examples in which a reinforcing part is installed on the optical path side, such as the carriage (holding member) of the first mirror shown in Japanese Patent Application Laid-open No. 49-99035. This is because there is a space at the top, and furthermore, because a lens mirror is used, a part for installing other equipment is placed on the second mirror side, so there is space. Incidentally, even in the exposure apparatus disclosed in the same publication, the reinforcing portion of the holding member of the second mirror is provided on the back side (opposite the optical path side) of the second mirror.

(Problem to be Solved by the Invention) In this way, the conventional holding member 10 for the second mirror 5 and the third mirror 6 in the optical system shown in FIG.
A reinforcing portion was formed to protrude within the space at the rear (on the side opposite to the optical path) defined by the casing. the result,
The larger the reinforcing portion is, the larger the space required on the rear side of the mirror becomes, and the more space is required for the device, which goes against the desire for compactness.

Therefore, it is an object of the present invention to provide a compact copying apparatus that does not require extra space even in a thin copying apparatus, and which is capable of handling mirrors that occur when a mirror holding member supporting a plurality of mirrors is rapidly accelerated or decelerated. It is an object of the present invention to provide a copying apparatus in which curvature and vibration of a holding member are prevented, and blurring and expansion/contraction of both images due to such vibrations are prevented.

(Means for Solving the Problem) The above object is to provide the reinforcement portion between the incident optical path and the reflected optical path, which are parallel to each other, on the incident and reflected optical path sides of the second mirror and the third mirror, which are perpendicular to each other. Second
This is achieved by providing a reinforcing portion with a wider width on the driving side of the mirror unit consisting of the mirror and the third mirror.

This reinforcing portion connects the driving side portion and the driven side portion of the mirror holding member, and is configured to fit between the incident optical path and the reflected optical path of the second mirror and the third mirror.

(Function) As mentioned above, the second mirror and the third mirror spend the same amount of time as the first moving time, which is half of that of the first mirror.
It moves at a speed of Never. Therefore, the reinforcing portions provided on the input/reflection optical path sides of the second and third mirrors do not protrude outward at the start and end of scanning of the optical system, and the optical path does not reach the reinforcing portions during movement. It is not blocked either.

(Example) Examples of the present invention will be described below. FIG. 1 shows an exposure apparatus to which the present invention is applied. In the figure, the original illumination lamp 3 and the first mirror 4 are held together by a holding member (not shown), and the original platen 4 is rotated at a predetermined speed V.
Move from left to right in the figure in parallel with . 2nd mirror 5
The third mirror 6 is held together by a holding member 10 and similarly moves from left to right in the drawing at a predetermined speed of 1/2V parallel to the document table 2 and in synchronization with the first mirror 4. By this synchronous movement, the original image is projected onto the photoreceptor 9. Synchronous driving of the first mirror 4, second mirror 5, and third mirror 6 is performed by a known driving means (not shown). FIG. 4 is a top view of a mirror holding member that is a typical embodiment of the present invention. The holding member 10 is formed as a frame body as shown in the figure, and can be made of metals such as iron and aluminum, as well as synthetic resin with high hardness, but it is manufactured by die-casting using aluminum. Preferably. This mirror holding member 10 is mainly composed of a side edge 10A and a side edge 10B located on the front side of the mirror (on the reflection side of the mirror).
A mirror support member, which will be described later, is joined to the portion 0A.

As described above, this mirror holding member 10 is attached with a pulley 11 and a guide roller 14, similar to the one shown in FIG. 3, and is pulled by the wire 12 to move back and forth.

As shown in FIG. 4, the reinforcing portion 10B extends from the side where the pulley 11 is provided, that is, the drive side of the holding member 10, to the driven side where the guide roller 14 is provided, and extends from the drive side where the guide roller 14 is provided. It has a wide portion 10B' that gradually increases in width.

FIGS. 5 and 6 show a mirror holding member 10 of the present invention.
FIG. 5 is a top view and FIG. 6 is a side sectional view. Both ends of the second and third mirrors 5 and 6 are secured to the mirror support member 1 using screws using a holding member 17.
It is fixed at 5. The mirror supporting member 15 has a substantially Y-shaped cross section with right angles, and its rear portion is fixed to one side edge 10A of the mirror holding member 10 using a screw 16.

In this embodiment as well, the reinforcing portion 10B is the pulley 1
1 is provided and extends from the drive side where it engages with the guide rail 13 to the driven side where the guide roller 14 is provided, and the drive side is formed wide as shown by 10B'.

The mirror unit configured in this way has a pulley 1 attached to one end of the mirror holding member 10.
1 and moves along a guide rail 13.

(Effects of the Invention) As the present invention is configured as explained above, even though the mirror holding member is provided with a reinforcing part, the machine can be made thin and the length can be minimized without increasing the size of the machine. It can be made more compact.
Furthermore, in the present invention, the shape of the reinforcing part, especially its width, can be sufficiently adjusted without being subject to the constraints of increasing the size of the machine or obstructing the optical path. Strength and rigidity are ensured. As a result, vibrations of the mirror, etc. are prevented, and a high quality copy image can be obtained. Further, for the same reason, it is possible to reciprocate the second mirror and the third mirror at high speed, and the speed of the copying machine can be increased at the same time. Furthermore, for the same reason, it becomes possible to use a long mirror, making it possible to copy large originals.

[Brief explanation of drawings]

FIG. 1 is a conceptual diagram showing an exposure optical system to which the present invention is applied, and FIG. 2 is a conceptual diagram showing a conventional second exposure optical system in the same optical system.
A side view of the holding part of the third mirror, FIG. 3 is a top view of the same,
FIG. 4 is a top view of a mirror holding member showing a typical embodiment of the present invention, FIG. 5 is a top view showing another embodiment of the same holding part, and FIG. 6 is a side sectional view of the same. Explanation of the main parts of the figure, 5...second mirror, 6...third mirror, 10...mirror holding member, 10B...reinforcement part.

Claims (1)

[Scope of Claims] 1 a document table; b a first mirror movable in parallel at a predetermined angle with respect to the document table in order to scan the document and perform slit exposure; and c the first mirror. d) a second light source capable of receiving and reflecting the light reflected by the first mirror and moving parallel to the document table with the same inclination angle as the first mirror; a mirror; e a third mirror capable of receiving and reflecting the light reflected by the second mirror and moving parallel to the document table; f the second mirror and the third mirror are integrally formed at right angles to each other; a mirror holding member capable of moving in parallel with the document table; g moving the first mirror and the light source at a predetermined speed V;
and moving the second mirror, the third mirror, and the holding member synchronously at a predetermined speed of 1/2V,
a driving means connected to one end of the holding member, wherein the holding member is connected to the second mirror and the third mirror.
It is arranged on the input/reflection optical path side of the mirror and between the input optical path of the second mirror and the reflection optical path of the third mirror, extends from the driving side end to the driven side end, and the driving side end 1. A copying apparatus comprising a reinforcing portion having a width wider than the driven side end portion.