JPH0216499B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a slit exposure type optical scanning device in which an original and a lens are fixed and a scanning system is provided on the image field side.

Conventionally, among slit exposure scanning copying machines, microfilm printers, and the like, there are those that have a scanning system on the object world side and those that have a scanning system on the image field side. Here, the object world side is the region from the document to the lens in the optical path, and the image field side is the region from the lens to the photoreceptor.

Examples of the former are Tokko No. 6647, 1973, and Jitko No. 45,
6456, etc., and an example of the latter is
No. 46-30013, Jikko No. 13075, Special Publication No. 43-
No. 10259, Japanese Patent Publication No. 13474, Publication No. 13474, Japanese Patent Publication No. 1973-
No. 102041 etc. Generally, if there is a scanning system on the object world side, it is necessary to change the moving speed of the scanning system according to the copying magnification, but if there is a scanning system on the image field side, the moving speed of the scanning system does not depend on the copying magnification. It can be kept constant.

By the way, the conventional example shown in Japanese Patent Publication No. 46-30013 which has a scanning system on the image field side has only one mirror in the scanning system, and cannot use the vicinity where the chief ray coincides with the optical axis. However, there was a problem in that it required a lens with a wide angle of view. Jitsugyo 46
13075 and Japanese Patent Publication No. 43-10259 involve rotational movement as well as translational movement, which has the problem of complicating the mechanism.

By the way, the scanning system shown in Japanese Patent Application Laid-Open No. 53-102041 has a maximum angle of view with respect to the optical axis that is sufficient with a lens that is approximately half that of that shown in Japanese Patent Publication No. 46-30013. The mechanism is simple, as it can be scanned by just moving around.

In FIG. 1, a slit area of a fixed document 1 is projected into a slit shape by a lens 2 through mirrors 3 and 4 onto a drum 5 rotating in the direction of the arrow. Here, in the optical path, in front of the drum 5, a light flux regulating member 6 is provided to regulate the slit area. In such a system, the mirrors 3 and 4 work together to move the drum 6 in the tangential direction of the movement of the drum 6.
When the original 1 is moved at a speed of 1/2, the slit area of the original 1 is sequentially scanned, and the entire original is copied while the original 1 and the lens 2 remain fixed. However, the number of mirrors in this scanning system is two, and the configuration is such that the outgoing principal ray is in the direction of folding back the incoming principal ray, and because the drum and lens are spatially close to each other, the components around the drum There is a problem in that there is not enough space for the settings. Furthermore, if you try to widen the distance between the lens and the drum to allow more space for the setup, there is a problem that the mirror closer to the drum will be in the optical path, and the farther away from the lens the larger the angle of view of the effective light beam will be. be. Also, when the scanning system moves vertically, that is, vibrates in the direction of the incident optical axis,
There is a problem that the optical path length changes.

The present invention is a novel optical scanning system in which, unlike this, the direction of incidence of the optical axis into the scanning system and the direction of exit from the scanning system are the same, the drum and lens are spatially separated, and the mirror used can also be small. The purpose is to provide equipment. The purpose of this is to provide a fixed imaging optical system that forms an image of a document on a predetermined surface, a light flux regulating member that regulates a light beam so that the image of the document becomes a slit, and a fixed imaging optical system that forms an image of the document on a predetermined surface. and a scanning system consisting of a movable mirror disposed between a surface of In an optical scanning device that sequentially projects images onto a surface, the scanning system is composed of an odd number of mirrors of three or more that align an optical axis of incidence from the imaging optical system and an optical axis of exit from the scanning system in the same direction. This is accomplished by configuring.

Embodiments of the present invention will now be described from FIG. 2 onwards. FIG. 2 is a diagram of one embodiment of the present invention, in which light from the slit area of the original 1 is passed through the mirrors 7 and 8 by the lens 2.
9, passes through the light flux regulating member 6, and is projected onto the drum 5. Here, the input optical axis R1 and the output optical axis R
2 is set parallel. In such a system,
The mirrors 7, 8, and 9 constitute a scanning system and are integrally moved in the tangential direction of the movement of the drum 5 at a speed of 1/2 of the circumferential speed of the drum 5, so that the entire document is scanned while the document 1 and lens 2 remain fixed. Copied.

FIG. 3 is a schematic diagram regarding the optical axis, and FIG. 4 is an explanatory diagram of its equivalent system. In Figure 3,
A scanning system M consisting of mirrors 7, 8, and 9 moves in the x direction with respect to the fixed document 1 and lens 2, but in FIG. System M is fixed and original 1
and a system in which the lens 2 moves in the -x direction.

Here, in FIG. 4, the relationship between the input optical axis R1 before movement and the input optical axis R1' after movement is opposite to the relationship between the output optical axis R2 before movement and the output optical axis R2' after movement. .

That is, what is on the right hand in the direction of travel of R1 on the input side of the scanning system M becomes on the left hand in the direction of travel on the exit side of the scan system M. (See dashed line).

This is because the scanning system M has an odd number of mirrors. In this embodiment, the scanning system M consists of three mirrors 7, 8, and 9.
If there are an odd number of mirrors, such as three or more, the same relationship as in FIG. 4 will be achieved no matter what mirror arrangement is used, with R1 and R2 being parallel.

In FIG. 4, the optical axis is simply bent by mirrors 7, 8, and 9, and the optical axis length remains unchanged even when scanning is performed, and the imaging relationship is maintained.
When the original 1 and the lens 2 are displaced by a distance a in the -x direction, they are also displaced by the same distance a in the +x direction on the image plane.

In the system after the movement in Fig. 4, the overall direction is a
When displacement is given by , the system shown in Figure 3 is obtained. That is, if the scanning system M moves in the direction of movement of the image plane at a speed 1/2 of the speed of movement of the image plane, the original 1 and lens 2 are fixed and the entire original is copied.

FIG. 5 shows another embodiment of the present invention, in which a scanning system M is composed of mirrors 10, 11, and 12, and is arranged near the middle between the lens 2 and the drum 5 in the optical path. In this system, the incident optical path to the mirror 11 and the reflected optical path from the mirror 12 intersect, and when the lens 2 is a fixed focus lens, it is easy to correct the total optical path length due to magnification conversion.

That is, when changing the magnification, by moving mirrors 11 and 12 together in parallel in the direction of the arrow as shown in FIG. 6, the optical path length can be easily corrected without changing the incident optical path and the exit optical path.

By the way, above, the input optical axis R1 and the output optical axis R2
have been described as being parallel, but this is because if they are non-parallel, the moving direction of the image plane will deviate from within the image plane, resulting in defocus. This is explained in FIG.

If we consider an equivalent system similar to that shown in FIG. 4 in which the incident optical axis R1 and the output optical axis R2 make an angle of θ, that is, if we consider the scanning system M to be a fixed system, then the original 1 and the lens 2
is displaced a in the -x direction, and on the image plane, the x direction and θ
It is displaced by a in the direction that makes an angle of . When this system is displaced by a in the x direction as a whole, as shown in Fig. 8, the direction of image movement is 1/1/2 from the initial image plane direction.
Since the angle is 2θ, the imaging relationship cannot be maintained on the drum surface. In other words, it will be defocused.

Although it has been described above that the scanning system M moves integrally in the present invention, it is also possible to move the individual mirrors constituting the scanning system M separately, resulting in a system equivalent to the system described above. include.

In addition, in the present invention, it is possible to configure the scanning system M with an odd number of three or more sheets, but the loss of light amount,
Considering optical adjustment, the minimum number of lenses, that is, three, is desirable. Furthermore, when changing the magnification, various known methods can be considered, in addition to the optical path length correction method described above. In addition, as for document exposure, either light transmitted through the document or reflected light from the document may be used.

In the optical scanning device of the present invention, even if the scanning system M moves up and down integrally, that is, moves in the direction of the incident optical axis, the imaging is not affected in any way, and the scanning system M
To make driving easier.

As described above, according to the present invention, it is possible to provide an optical scanning device having a scanning system including an odd number of three or more mirrors on the image field side and with the incident optical axis and the exit optical axis in the same direction.

[Brief explanation of drawings]

Fig. 1 is a diagram of a conventional optical scanning device, Fig. 2 is a diagram of an embodiment of the present invention, Fig. 3 is a schematic diagram regarding the optical axis, and Fig. 4 is a diagram of a system equivalent to the system in Fig. 3. ,
FIG. 5 is a diagram of another embodiment of the present invention, FIG. 6 is an explanatory diagram at the time of zooming, and FIGS. 7 and 8 are explanatory diagrams regarding the imaging relationship. In the figure, 1 is a document, 2 is a lens, 3 and 4 are mirrors, 5 is a drum, 6 is a light flux regulating member, 7, 8,
9, 10, 11, and 12 are mirrors.

Claims (1)

[Scope of Claims] 1. A fixed imaging optical system that forms an image of a document on a predetermined surface, a light flux regulating member that regulates a light flux so that the image of the document becomes a slit, and the imaging optical system. a scanning system consisting of a movable mirror disposed between the system and a predetermined surface, and by moving the scanning system, the image of the document held in a fixed state is slit-scanned. In the optical scanning device that sequentially projects onto the predetermined surface, the scanning system includes an odd number of three or more lenses that align the incident optical axis from the imaging optical system and the exiting optical axis from the scanning system in the same direction. An optical scanning device comprising a mirror. 2. The optical scanning device according to claim 1, wherein the scanning system moves in the same direction at half the speed of movement of the predetermined surface. 3. When changing magnification, a predetermined mirror of the scanning system is displaced in a predetermined direction to correct the optical path length.
Optical scanning device as described in section.