JPS5847682B2 - variable magnification optical device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an optical device having a variable magnification function, more specifically, an optical device in which the edge of one object is projected onto a fixed position on an image plane before and after changing magnification. Regarding.

The present invention provides, for example, a copying machine capable of variable magnification copying,
When setting a certain original and copying it at a plurality of different magnifications, it is used to configure so that the edge of copy paper such as A4, B5, etc. can always be placed at a constant position.

Alternatively, in a facsimile, when originals of various sizes are set with one edge aligned and projected onto the photoelectric conversion unit at a desired magnification, the edge of the original image is always placed at a fixed position on the photoelectric conversion unit. It is used to eliminate waste in transmissions.

As shown in FIG. 1, an example of the conventional variable magnification optical device includes an object point surface 2 on which a document is placed, a projection lens 1, and image point surfaces 13 and 13' on which copy paper is placed. Of course, the object point plane 2 and the image point planes 13 and 13' are conjugate.

On the other hand, when changing the magnification, move the projection lens 1 in the direction of its optical axis A, in the direction perpendicular to the optical axis B, or by the combined distance of A and B to the position 1', and move the projection lens 1 to the position 1'. is 1
Move to 3'.

At this time, the lower end 3 of the object plane 20, that is, the lower edge of the document, is projected onto the upper ends 4, 4' of the object plane 13, but the heights of both from the optical axis of the projection lens 1 are constant.

By the way, in the above-mentioned conventional variable magnification optical device, it is necessary to accurately move the projection lens and maintain the parallelism of the projection lens before and after movement by using a lens holding frame, a sliding guide, etc. with high processing precision. Ta.

Furthermore, since the projection lens moves linearly, there is also the problem that the rotational power of an electric motor or the like, which is easy to control and inexpensive, cannot be used as is.

An object of the present invention is to provide a variable magnification optical device that solves the problems of the conventional variable magnification optical device. In a variable magnification optical system that aligns the image height position on the surface, the object point side
A projection lens used with the image point side reversed is rotated about 1800 times around the center of point symmetry of two positions before and after zooming of the projection lens, which change the position of the projection lens in the optical axis direction. This means changing the magnification.

The present invention will be explained below with reference to an embodiment of a copying machine.

FIG. 2 shows the optical principle of the present invention, and parts common to those in FIG. 1 are given the same reference numerals and their explanation will be omitted.

The projection lens 1 shows the state before zooming, and the projection lens 1' shows the state after zooming, and the photographing lens 1 is rotated by 1800 degrees from the projection lens 1'. It is attached to a disk 5 that rotates around the center of point symmetry of the projection lenses 1 and 1'.

In other words, if we consider a coordinate system with the origin at the position of the projection lens 1 and express the position of the projection lens 1' with coordinates (a, b), then the disk 5 will be at the point (view; -!2) on the main body 22. It is to be pivoted.

4, 4' are image points at the lower end 3 of the object plane, which are object points off the optical axis, and copy paper is supplied to the object plane 13, 13'. When used as printing plates, it is desirable that one edge of these photographic papers has a constant height on the optical axis of 4 and 4'.

The mechanical configuration of this embodiment is as shown in FIG.
is pivotally attached to the main body (not shown) at the point symmetry center 8, and a gear 7 is provided on its outer periphery.

8 is an electric motor, which is engaged with the disc 5 via a gear 9.

Adjustment screws 11, 11' screwed into the main body 10 engage with protrusions 12 on the disc 5 to finely adjust the position and direction of the projection lenses 1, 1'.

In the above configuration, first, the projection lens 1 is in the position shown in FIG. 3, and the adjustment screw 11 and the protrusion 12 are in contact with each other.

Next, when changing the magnification, the moke 8 is rotated counterclockwise to rotate the disc 5.

The projection moves to position 12' and comes into contact with adjustment screw 11, and the projection lens is fixed at position 1', completing the magnification changing operation.

The variable magnification optical device of the present invention constructed as described above has a simple structure because the operating mechanism is composed of only pivot movement.
It has the advantage of being able to use the rotational force of an electric motor that operates smoothly, is easy to control, and is inexpensive.

The projection lens can be easily and accurately positioned by limiting the rotation of the projection lens mounting disk.

Therefore, the present invention has great advantages in terms of structure and operation, and its effects are particularly significant when applied to copying machines and facsimile IJs.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the principle of a conventional variable magnification device. FIG. 2 is a diagram showing the principle of the variable magnification device of the present invention. FIG. 3 is a plan view of a variable magnification optical device that is an embodiment of the present invention. 1, 1'...Projection lens, 2...Object point surface, 5...Disc, 7...Gear, 8...
...Electric motor, 11, 11'...Adjustment screw, 1 2, 12'...Protrusion.

Claims (1)

[Claims] 1 In a variable magnification optical system in which the height position of the image on the image point surface corresponding to one edge of the object point surface is aligned, a projection lens that is used with the object point side and image point side reversed is A variable magnification optical device, characterized in that the projection lens is rotated approximately 180 degrees around a center of point symmetry between two positions before and after the variable magnification to perform variable magnification.