JPH04294342A - Optical device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical device used in a high-speed copying machine with a fixed light source, which is a slit exposure type copying machine.

0002

2. Description of the Related Art Conventionally, in many scanning illumination systems of slit exposure type copying machines, a light source moves integrally with a scanning mirror. However, in the case of high-speed copying machines, there is a limit to the speed-up of a movable light source type due to the weight and durability of the light source. Therefore, for the purpose of further increasing speed, an illumination optical system with a fixed light source is USP. Re29017, Utsukai Showa 54-
173745, etc. ■USP. A light source is provided near the Re29017 manuscript placement surface, and a parabolic mirror is provided to surround the light source. The light beam emitted from the light source is reflected by the parabolic mirror in parallel along the optical path along the document placement surface. ■Utility Model Application No. 54-173745 A light source was provided near the manuscript placement surface, and a quadratic curved reflector was provided near the light source. Furthermore, a focusing lens is placed in the optical path. The light beam from the light source is guided through an optical path parallel to the document placement surface.

0003

[Problem to be Solved by the Invention] However, the above-mentioned method (2) has the disadvantage that it cannot be used in recent copying machines that pursue compactness because the parabolic mirror becomes large. In addition, since the lens (2) has a converging lens placed in the center of the optical path, it is difficult to support the lens, and the light beam is easily eclipsed by the supporting member.

The present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide an optical device that is not only compact in structure but also easy to support a lens.

[0005]

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a light source at a predetermined distance from the document placement surface in order to form an optical path along the document placement surface. A first reflecting means having a concave reflecting surface with the light source as the center of curvature is provided at a position opposite to the optical path, and a parabolic reflection with the light source as the focal point is provided between the light source and the document placement surface. A second reflecting means having a surface was provided, and a first cylindrical lens having the light source as a focal point was provided in the optical path.

[0006] Furthermore, in order to form an optical path along the document placement surface, a light source is provided at a predetermined distance from the document placement surface;
A third reflecting means having a concave reflecting surface with the light source as the center of curvature is provided at a position opposite to the optical path of the light source, and a third reflecting means with the light source as the focal point is provided between the light source and the document placement surface. Two cylindrical lenses are provided, and a third cylindrical lens with the light source as a focus is provided in the optical path, and a light beam that has passed through the second cylindrical lens is guided to the optical path between the document placement surface and the second cylindrical lens. A fourth reflecting means was provided.

[0007]

[Operation] The operation of the present invention based on the above structure is such that a part of the light beam emitted from the light source passes through the first cylindrical lens and passes through the optical path parallel to the document placement surface. Furthermore, the light beam emitted from the light source toward the document placement surface is guided in parallel to the optical path by the second reflecting means. Furthermore, the light beam emitted from the light source toward the opposite side of the optical path is returned to the light source side by the first reflecting means, and is guided to the optical path by the second reflecting means.

On the other hand, a part of the light beam emitted from the light source passes through the third cylindrical lens and also passes through the optical path parallel to the document placement surface. Further, the light beam emitted from the light source toward the document placement surface is transmitted through the second cylindrical lens, and is guided in parallel to the optical path by the fourth reflection means. Further, the light beam emitted from the light source toward the opposite side of the optical path is returned to the light source side by the third reflecting means, and is guided to the optical path via the second cylindrical lens and the fourth reflecting means.

[0009]

EXAMPLE Next, the present invention will be explained based on FIG. FIG. 2A is a schematic front sectional view of a first embodiment in which the present invention is used as an optical system of a copying machine. A rod-shaped light source (such as a fluorescent lamp) 2 is fixed to one end of the document table glass 1 having a document placement surface 50 for forming an optical path 51 below the document table glass 1. . There is a predetermined distance between the light source 2 and the document glass 1, and the light source 2 is parallel to the document glass 1 in the longitudinal direction.

[0010] A cylindrical mirror 3a serving as a first reflecting means for covering the lower part of the light source 2 is provided at a position on the opposite side of the light source 2 from the optical path 51. This cylindrical mirror 3a has a concave reflective surface 3a' having the light source 2 as its center of curvature. Further, a parabolic cylindrical mirror 3b serving as a second reflecting means is provided between the light source 2 and the document table glass 1. This parabolic cylindrical mirror 3b has a parabolic reflecting surface 3b' with the light source 2 as its focal point. The reflecting mirror 3 is constructed by combining the parabolic cylindrical mirror 3b of the cylindrical mirror 3 with the parabolic cylindrical mirror 3b.

Further, a collimator cylindrical lens 5 as a first cylindrical lens having the light source 2 as a focal point is provided in the optical path 51 and directly near the light source 2. Furthermore, a collimator cylindrical lens 5 and a light source 2
A heat insulating glass 4 is provided between the two. Since the collimator cylindrical lens 5 is located on the lower side of the optical path 51, a support member (not shown) provided below does not block the optical path 51. Therefore, there is no vignetting of the luminous flux. Furthermore, the overall configuration is compact, contributing to miniaturization of copying machines.

A first exposure unit A and a second exposure unit B are provided below the original platen glass 1 and are capable of reciprocating in parallel to the original platen glass 1 in the direction of the arrow. The first exposure unit A includes a cylindrical mirror 6 that illuminates the illumination area 1a of the document placement surface 50, and a first reflection mirror 7. The second exposure unit B has second and third reflection mirrors 8 and 9. And the first and second exposure units A,
B is connected to the scanning control circuit 13 via a motor (not shown). This scanning control circuit 13 is for causing the first and second exposure units A and B to scan in conjunction with the rotation of the photosensitive drum 12.

Furthermore, an imaging lens 10, a fourth reflecting mirror 11, and a photosensitive drum 12 are provided below the document table glass 1.

Next, the operation of the first embodiment will be explained. First, the light beam emitted from the light source 2 toward the optical path 51 side passes through the insulating glass 4, passes through the collimator cylindrical lens 5, and travels in the optical path 51 parallel to the document placement surface 50, and then passes through the cylindrical mirror. Head to 6. Further, the light beam directed upward from the light source 2, that is, toward the document placement surface 50 side, is reflected by the parabolic cylindrical reflection mirror 3b, and then
The light passes through the insulating glass 4 and reaches the optical path 51, and travels parallel to the document placement surface 50. Furthermore, among the light beams directed from the light source 2 to the side opposite to the optical path 51, the downward light beams are reflected by the cylindrical mirror 3a and return to the light source 2, and then pass through the parabolic cylindrical reflecting mirror 3b and the insulating glass 4. It is guided to the optical path 51 through the optical path. Further, the light beam directed to the right in the figure is reflected by the cylindrical mirror 3a, returns to the light source 2, and is guided to the optical path 51 via the insulating glass 4 and the collimator cylindrical lens 5.

As described above, all the luminous flux emitted from the light source 2 is efficiently converted into a luminous flux parallel to the document placement surface 50 and travels along the optical path 51, and the cylindrical mirror 6
to the illumination area 1a. Then, the reflected light from the original surface of the original placing surface 50 is reflected by the first reflecting mirror 7 for exposure, the second reflecting mirror 8, and the third reflecting mirror 9, and enters the imaging lens 10 to form an image. The imaging light from the lens 10 is reflected by the fourth reflecting mirror 11 for exposure, and the photosensitive drum 12 is exposed. When scanning the document surface, light source unit D
The cylindrical mirror 6, the first reflecting mirror 7, the second reflecting mirror 8, and the third reflecting mirror 9 can be moved integrally while being fixed near one end of the document table. In order to keep the imaging magnification of exposure constant, the amount of movement of exposure unit A, which consists of a cylindrical mirror 6 and a first reflecting mirror 7 for exposure, and the exposure unit B, which consists of a second reflecting mirror 8, and a third reflecting mirror 9, is adjusted. The ratio should be 2:1. The scanning system control circuit 13 controls the scanning positions of the units A and B in conjunction with the rotation of the photosensitive drum 12.

FIG. 1(B) shows a second embodiment. A light source 2 is provided below a document table glass 1 having a document placement surface 50 . Further, at a position of the light source 2 on the opposite side to the optical path 51, a concave reflective surface 4a with the light source 2 as the center of curvature is provided.
Cylindrical mirror 1 as a third reflecting means having
4 is provided.

Further, a collimator cylindrical lens 18 serving as a second cylindrical lens having the light source 2 as a focal point is provided between the light source 2 and the document placement surface 50. Then, the light source 2 and the collimator cylindrical lens 18
An insulating glass 17 is provided horizontally between the
Collimator cylindrical lens 18 and document table glass 1
A reflecting mirror 19 as a fourth reflecting means is provided between the two.

Furthermore, a collimator cylindrical lens 16 as a third cylindrical lens is provided immediately near the light source 2 in the optical path 51, and a heat insulating glass 15 is vertically disposed between the light source 2 and the collimator cylindrical lens 16. It is provided in

Next, the operation of the second embodiment will be explained. First, a beam of light emitted from the light source 2 toward the optical path 51 passes through the insulating glass 15 and the collimator cylindrical lens 16, and travels parallel to the document placement surface 50 in the optical path. Furthermore, the light flux directed from the light source 2 toward the document placement surface 50 is
Insulating glass 17, collimator cylindrical lens 18
is transmitted through the optical path 51 via the reflecting mirror 19.
be led to. Furthermore, the light beam directed to the side opposite to the optical path 51 of the light source 2, that is, to the right in the figure, is reflected by the cylindrical mirror 14 and returns to the light source 2, and is reflected by the insulating glass 15.
, passes through the collimator cylindrical lens 16 and reaches the optical path 51. Further, the light beam directed downward from the light source 2 is reflected by the cylindrical mirror 14 and returns to the light source 2,
Insulating glass 17, collimator cylindrical lens 16
is transmitted through the optical path 51 by the reflecting mirror 19.
be led to.

As described above, the light beam emitted from the light source 2 travels parallel to the document placement surface 50 in the same manner as in the first embodiment. Therefore, the same effects as in the first embodiment can be obtained.

[0021]

Since the present invention is constructed as described above, the construction can be made compact and vignetting of the light beam due to the lens support member can be prevented.

[Brief explanation of drawings]

FIG. 1(A) is a schematic front sectional view of a first embodiment of the present invention, and FIG. 1(B) is a schematic front sectional view of a main part of a second embodiment.

[Explanation of symbols]

2 Light source 3a Cylindrical mirror (first reflecting means) 3b
Parabolic cylindrical mirror (second reflecting means) 5 Collimator cylindrical lens (first cylindrical lens) 14 Cylindrical mirror (second reflecting means) 16
Collimator cylindrical lens (third cylindrical lens) 18 Collimator cylindrical lens (second cylindrical lens) 19 Reflection mirror (fourth reflection means) 50 Document placement surface 51 Optical path

Claims (2)

[Claims] Claim 1: In order to form an optical path along the document placement surface, a light source is provided at a predetermined distance from the document placement surface, and the light source is placed at a position on the opposite side of the document placement surface with a curvature. A first reflecting means having a concave reflecting surface at the center is provided, a second reflecting means having a parabolic reflecting surface with the light source as the focal point is provided between the light source and the document placement surface; and a first cylindrical lens that focuses on the light source. 2. In order to form an optical path along the document placement surface, a light source is provided at a predetermined distance from the document placement surface, and the light source is curved at a position opposite to the optical path. A third reflecting means having a concave reflecting surface at the center is provided, a second cylindrical lens with the light source as the focal point is provided between the light source and the document placement surface, and a second cylindrical lens with the light source as the focal point is provided in the optical path. An optical device including three cylindrical lenses, and a fourth reflecting means for guiding a light beam transmitted through the second cylindrical lens to an optical path between the document placement surface and the second cylindrical lens.