JPH0795157B2 - Projection optics - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projection optical system suitable for projecting an object plane which is an original image onto an image plane in an optical device such as an electrophotographic copying machine or a facsimile machine, and more particularly to a light-converging optical transmission body or The present invention relates to a projection optical system suitable for projecting an object surface onto an image surface at various magnifications such as reduction or enlargement, using a so-called compound eye system in which a plurality of lens elements including microlenses are arranged in a row. .

[0002]

2. Description of the Related Art Conventionally, in an optical device such as an electrophotographic copying machine or a facsimile, a compound eye system is used to project an object surface onto an image surface at a predetermined magnification. As the projection method, there are used two methods: a method by an erecting real image system that projects an object surface as an erecting real image on the image surface and a method by an inverted real image system that projects an object surface as an inverted real image on the image surface. Of these, the inverted real image system requires only one image formation as compared with the two times image formation of the erect real image system, so that the total optical length can be shortened, the entire optical system can be simplified, and the entire apparatus can be easily downsized. It has features.

Therefore, the inverted real image system is used in many electrophotographic copying machines. However, in the inverted real image system, the object image rotates 180 degrees on the image plane. Therefore, when using the compound eye system, the object image by each inverted real image system is maintained on the image plane by using a reflecting mirror or the like. It is necessary to overlap while doing.

Further, even if the aforementioned 180 ° rotational shift is corrected by an appropriate means, in the case of zooming, the "image shift" of the image that is peculiar to zooming is determined as determining the imaging performance of the compound eye system.
There is a "magnification shift". Since the causes of these problems are the same in principle, the conventional erecting real image system will be described below as an example.

In the erecting real image system, a so-called erecting equal-magnification system in which the projection magnification is the same is proposed in, for example, Japanese Utility Model Publication No. 48-18204. In the publication, as shown in FIG. 2, a compound eye system 20 is composed of a plurality of erecting real image systems 21 composed of microlenses, and a partial image in a predetermined range of the object plane 1 is projected onto the image plane 2.
They are superimposed and form an integral image. As a result, a large object plane that cannot be covered by one erecting real image system is projected onto the image plane.

The compound eye system shown in FIG. 2 is constructed so that the optical axes of the erecting real image systems 21 are parallel to each other because the projection magnification is equal, and each ray on the optical axis is the object plane 1 and the image. It is configured to intersect the plane 2 at right angles. This makes it possible to form an integral image by superimposing projected images on the image plane, so-called multiple images, by the respective erecting real image systems 21 on the image plane.

Generally, in order to make a projection optical system having a compound eye system a minute system or a magnifying system, if the object distance is changed from the state of a unity magnification system, the magnification of each erecting real image system changes, whereas
Since the optical axis interval of each erecting real image system remains the same size, the multiple images by the erecting real image systems do not overlap on the image plane and are displaced, causing so-called image displacement. The image shift phenomenon at this time is a cause of significantly deteriorating the optical performance of the projected image. For example, Japanese Patent Application Laid-Open No. 57-16415 proposes a method of correcting an image shift of a multiple image when reduced projection or enlarged projection is performed by using a compound eye system including a plurality of erect real image systems. In this publication, as shown in FIG. 3, a plurality of erecting real image systems 31 forming a compound eye system 30 are arranged such that their optical axes gradually incline with respect to the optical axis 311 of the erecting real image system 310 at the center.
This corrects the deviation of the multiple images. However, in this compound eye system, the optical performance and the optical axis length (optical length of the optical axis from the object plane to the image plane) are different for each erect real image system. When the light rays on the optical axis of the erecting real image system for projection intersect the object plane and the image plane, they largely deviate from the vertical. Therefore, in the erecting real image system 41 whose inclination is large as shown in FIG. 4, the object plane having the same projection magnification is inclined from the normal object plane 1 and the object plane 42 is inclined.
It becomes like.

On the other hand, the image plane having the same projection magnification is also inclined like the image plane 43 with respect to the regular image plane 2. As a result, the optical path length LL41 shown in FIG.
And LL42, the so-called "magnification deviation" in which the imaging magnification partially differs within the same field of view by an amount corresponding to the difference in length.
Will occur.

As described above, in the conventional projection optical system using the compound eye system, the magnification shift occurs even if the shift of the multiple images is corrected, and a projection image having high optical performance can be obtained in the projection other than equal magnification. Is getting harder.

Further, in the publication, if necessary, the entrance end surface or the exit end surface of each erecting real image system is decentered or a refracting power is added to reduce the deviation in magnification. The whole optical system becomes complicated. In principle, the optical axis of each erecting real image system cannot be perpendicular to the object plane and the image plane.Therefore, there is a limit to this kind of correction, and it is difficult to remove the magnification deviation by such means. is there.

In addition to the above, for example, a compound eye system composed of a plurality of erecting real image systems, which corrects image shift of multiple images when performing reduced projection or enlarged projection, is disclosed in, for example, Japanese Patent Laid-Open No. 59-4542.
No. 0, JP 59-216115 A and the like are proposed.

In Japanese Patent Laid-Open No. 59-45420, as shown in FIG. 5, an erecting real image system is provided on at least one of the object plane 1 side and the image plane 2 side of a compound eye system 50 composed of a plurality of erecting real image systems 51. A projection optical system is proposed in which image deviation of a multiple image is corrected by arranging light beam deflecting members 52 and 53 each having a Fresnel lens having a different deflection angle.

Further, in Japanese Patent Laid-Open No. 59-216115, as shown in FIG. 6, a plurality of spherical lenses are provided on at least one of the object plane 1 side and the image plane 2 side of a compound eye system 60 composed of a plurality of erecting real image systems 61. A projection optical system is proposed in which 62 and 63 are arranged to correct the image shift of multiple images.

However, in the projection optical systems proposed in the above two publications, the optical axes of the erecting real image systems are different, and the optical axes of the erecting real image systems projecting the periphery of the object plane are different. It is greatly inclined with respect to the object plane and the image plane. Therefore, although the image shift of the multiple image can be corrected as described above, the magnification shift occurs, which causes a great decrease in the optical performance of the projected image.

The above-mentioned magnification deviation similarly occurs when the compound eye system is constructed by an inverted real image system due to the same cause as in the case of the erect real image system.

[0016]

SUMMARY OF THE INVENTION The present invention is directed to a compound eye system including a plurality of inverted real image systems, and when projecting an object plane including a magnification other than the same magnification such as reduction or enlargement, an image shift of multiple images occurs. It is an object of the present invention to provide a projection optical system in which the optical performance of a projected image is improved by simultaneously correcting and correcting or eliminating the magnification shift.

A further object of the present invention is to provide a projection optical system capable of reducing unevenness in light quantity caused by superimposing light quantity distributions on the image plane by respective inverted real image systems and obtaining a good projection image as a whole. is there.

[0018]

The projection optical system of the present invention comprises:
When a compound eye system having a plurality of inverted real image systems is used to project and superimpose the object plane on the image plane at a reduced or magnified magnification, a deflection unit having a plurality of optical members for deflecting the light flux is disposed in the optical path, The inverted real image system is configured such that each light ray on its optical axis intersects with each other in space, and each light ray on the optical axis of the plurality of inverted real image systems is perpendicular to at least one of the object plane or the image plane. It is characterized in that the plurality of inverted real image systems are constituted by the same lens element and are arranged on different planes so that the respective optical path lengths are the same.

In particular, each of the plurality of optical members comprises a plurality of reflecting mirrors facing each other for each of the plurality of inverted real image systems,
The angle of the plurality of reflecting mirrors is changed for each inverted real image system, and the deflecting means is provided at least on one side between the object plane and the compound eye system or between the image plane and the compound eye system. It is characterized in that the optical member is provided, and that the optical member is composed of a reflecting mirror, and the one reflecting mirror deflects a light flux passing through at least two of the plurality of inverted real image systems.

Besides, the features of the present invention are described in the embodiments.

[0021]

FIG. 1 is a schematic view of an optical system of one embodiment when the projection optical system of the present invention is composed of a reduction system. In the figure, 1 is an object plane, 2 is an image plane, 10 is a compound eye system, and is composed of a plurality of inverted real image systems 11, 12, and 13.

Points A2, B2, C2 and points A3, B3, C3
Is a position where optical members for deflecting the light fluxes passing through the inverted real image systems in predetermined directions are arranged in rows.
Particularly in this embodiment, the optical member is composed of a reflecting mirror and is arranged with a predetermined inclination.

In this embodiment, the reflecting mirror is omitted for the sake of simplicity, and only the optical paths of the light rays on the optical axis of each inverted real image system when reflected by the reflecting mirror are shown.

Points A1, B1, C1 on the object plane 1 and points A4, B4, C4 on the image plane 2 are inverted real image systems 1.
It is the position where the light rays L1, L2, L3 on the optical axes 1, 12, 13 intersect, respectively.

In this embodiment, optical members are arranged at points A2 to C2 on the object plane 1 with respect to one direction of points A1 to C1.
It constitutes one optical member row. The other one on the object plane 1
Similarly, with respect to the points D1 to F1 in the direction, optical members are respectively arranged at the points D2 to F2 to form one optical member row. The two optical member rows are arranged in a step shape in the vertical direction with respect to the object plane 1. In this embodiment, one optical deflector is composed of two optical member rows.

Also on the image plane 2 side, one optical member row is composed of a plurality of optical members arranged at points A3 to C3 similarly to the object plane 1 side, and one optical member row is arranged from a plurality of optical members arranged at points D3 to F3. One optical member row is configured, and these two optical member rows are provided in a step shape in the vertical direction with respect to the image plane 2. This constitutes the deflecting means on the image plane side.

Further, in the present embodiment, a plurality of optical member rows on the object side and the image surface side are provided in a stepwise manner so that a plurality of inverted real image systems for each optical member do not interfere with each other in space. ing.

In the present embodiment, a predetermined range of the object plane 1 is reflected by the inverted real image system 13 arranged at the point C3 through a reflecting mirror in which the object plane near the point C1 is arranged at a position C2 with a predetermined inclination. After reflection by the mirror, point C4 on image plane 2
Reduced projection in the vicinity. At this time, in this embodiment, point C
1, C2, C3, C4 are configured to be located on the same plane. As a result, the loci of the optical axes of the inverted real image systems are on the same plane, and the projected images of the inverted real image systems are relatively rotated so as not to cause "rotation blur". These are exactly the same for other inverted real image systems, and a predetermined range of the object plane 1 is reduced and projected onto the image plane.

When the projection magnification is m, the ratio of the distances _{DA1 and B1} between the points A1 and B1 on the object plane 1 and the distances D _{A4 and B4} between the points A4 and B4 on the image plane 2 is It is set to m times. The same applies to the intervals at other points.

In the coordinate system shown in FIG. 1, for example, the point B
1, B2, B3, expressed the B4 coordinate B1 = (x, LL / 2 , h / 2) B2 = (x, LL / 2, -h 1) B3 = (- mx, -LL / 2, h ₂ ) B4 = (-mx, -LL / 2, -h / 2).

At this time, regarding the coordinate points h ₁ and h ₂ of the points B2 and B3 in the Z-axis direction, let L be the optical axis length of one inverted real image system.

[0032]

[Equation 1] Is configured to be. Here, the optical axis length L is expressed as a function of the projection magnification m, and is a value that varies depending on the projection magnification m.

In this embodiment, projected images on the image plane formed by respective inverted real image systems, so-called multiple images, are changed in shape and inclination of a plurality of reflecting mirrors provided on the object plane 1 and image plane 2 sides, respectively.
The optical axes of the inverted real image systems intersect in space, that is, the optical axes of the inverted real image systems intersect with each other when projected onto one plane, so that they overlap each other to form an integral image as a whole, Prevents deviation.

Further, in this embodiment, the inclinations of the respective inverted real image systems and the respective reflecting mirrors are set so that the light rays L1 to L3 on the optical axis of the respective inverted real image systems intersect perpendicularly with the object plane 1 and the image plane 2. is doing. That is, after the rays L1 to L3 on the optical axis of each inverted real image system are reflected by the reflecting mirror, they become parallel to each other, and the object plane 1 and the image plane 2
It is configured to intersect vertically with.

This prevents the occurrence of "magnification shift" which occurs when the light beam on the optical axis described in FIG. 4 intersects the object plane or the image plane at an angle.

FIG. 7 is a top view of a part corresponding to one direction of points A1 to C1 of FIG. 1 at this time, and FIG. 8 is an object plane 1 of FIG.
It is a side view containing point B1 and point E1 above.

In FIGS. 7 and 8, the reference numerals are exactly the same as those shown in FIG.

In FIG. 7, points A1 and B on the object plane 1
1, a straight line D1 connecting C1 and points A4, B4 on the image plane 2
The straight line D4 connecting C4 is parallel. Then, when the optical axes of the plurality of inverted real image systems 11, 12, and 13 are respectively extended, each element is set so as to intersect or simply intersect at a point O in space.

When the projection magnification m of the projection optical system at this time is expressed by using the distances D71 and D72 between the respective elements shown in FIG. 7, m = D72 / D71.

In this embodiment, a plurality of inverted real image systems are composed of the same lens element. Therefore, the respective inverted real image systems are three-dimensionally arranged on different planes so that the respective optical axis lengths are the same. As a result, all the inverted real image systems are projected under the same conditions, and the optical characteristics in each inverted real image system are made uniform.

The positions A2, B2, C2 and the positions A3, B3, C3 of the respective reflecting mirrors can be arbitrarily set within a range satisfying the expression (1), but once each position of one reflecting surface is determined. For example, the rest can be sequentially determined according to the characteristics of the inverted real image system.

It goes without saying that, in this embodiment, two or more optical member rows may be provided in a step shape.

With the above-described structure, in the present embodiment, a large area of the object plane 1 in a plurality of directions is simultaneously projected onto the image plane 2 to improve the projection efficiency and to superimpose the light amount distributions of the respective inverted real image systems. A good projection image is obtained by reducing the unevenness of the light amount that occurs.

In this embodiment, the case where the reflecting mirror is used as the optical member is shown. For example, as shown in FIG. 9, the prism member 90, 91 is used to make the light ray L3 on the optical axis of the inverted real image system 13.
Even if the optical axis is configured to intersect the object plane 1 and the image plane 2 at right angles, the image shift and the magnification shift can be similarly prevented.

In the embodiment shown in FIG. 1, the case has been described in which the light beam on the optical axis of the inverted real image system intersects the object plane and the image plane perpendicularly and the magnification deviation is completely corrected. If the deviation of the magnification is allowed, the light rays on the optical axis may intersect perpendicularly to at least one of the object plane and the image plane.

In the above embodiment, each inverted real image system extends from the first reflecting mirror having a separate reflecting surface for each inverted real image system to the final reflecting mirror having a separate reflecting surface through the inverted real image system. It is preferable to dispose a light-shielding member in order to prevent such crosstalk.

Further, in the above embodiments, the case where the projection optical system is applied to the reduction system has been described. However, when the projection optical system is applied to the enlargement system, if the entire reduction system is reversed, the same result is obtained. The invention can be applied.

In this embodiment, a common reflecting surface for simply deflecting a light beam is provided on at least one of the object plane and the deflecting means or the image plane and the deflecting means, and the entire projection optical system is constructed. The above arrangement may be set arbitrarily.

Such a setting is effective when the relative relationship between the object plane and the image plane is brought to a predetermined positional relationship and when the front-back relationship of the image is corrected.

In this embodiment, if a slight image shift or magnification shift is allowed, one reflecting mirror may be used to deflect the light beams from a plurality of inverted real image systems.

In this embodiment, the case where the compound eye system is composed of six inverted real image systems is shown, but the object of the present invention can be achieved by providing two or more inverted real image systems.

In this embodiment, two deflecting means are used and one reflecting mirror is used as one deflecting means, but as described above, "rotation blur", "image shift", "magnification shift", etc. It is also possible to use a plurality of reflecting mirrors or refracting members as long as they are independently equivalent to the configuration for correcting the above and the object plane and the image plane. For example, as shown in FIG. 10 (A), the light rays from the object plane 1 may be guided not only in one plane but in another plane and then returned to the original plane. Also, FIG.
As shown in (B), when the number of reflecting mirrors constituting the deflecting means is increased so that the line segment 101 in one direction of the object plane 1 is projected onto the image plane 2 by each inverted real image system, Line segment 101
If the image is formed as one line segment 102 on the image plane 2 so that there is no so-called rotational deviation, an arbitrary configuration can be taken according to the relative positional relationship between the object plane and the image plane.

This is preferable because the degree of freedom in arrangement can be increased and an arbitrary configuration can be adopted according to the relative positional relationship between the object plane and the image plane.

As shown in FIGS. 11A and 11B, a compound eye system 111 composed of a plurality of inverted real image systems is provided between the object plane 1 and the deflecting means depending on the projection magnification and the object-image distance. It may be provided in any one direction between the image plane 2 and the deflecting means.

This is preferable because the optical axes of all inverted real image systems can be aligned and the structure is simplified.

In the present embodiment, when the inverted real image system has a space in the optical system like a microlens or the like, FIG.
As shown in (A), (B), and (C), a deflecting means may be provided at the spatial position. In the figure, reference numeral 121 is a microlens.

[0057]

According to the present invention, when a compound eye system including a plurality of inverted real image systems is used to perform reduced projection or enlarged projection of an object plane, a deflecting unit including a plurality of optical members for deflecting a light beam is used. It is possible to achieve a projection optical system in which both image shifts and magnification shifts of multiple images on the image plane are well corrected.

[Brief description of drawings]

FIG. 1 is a schematic diagram of an optical system according to an embodiment of the present invention.

FIG. 2 is an explanatory view of a part of a conventional projection optical system.

FIG. 3 is an explanatory diagram of a part of a conventional projection optical system.

4 is an explanatory view of a projected image of a part of FIG.

FIG. 5 is an explanatory diagram of a part of a conventional projection optical system.

FIG. 6 is an explanatory view of a part of a conventional projection optical system.

FIG. 7 is a top view of a portion of FIG.

FIG. 8 is a partial side view of FIG.

FIG. 9 is a partial side view of another embodiment of the present invention.

FIG. 10 is a partial side view of another embodiment of the present invention.

FIG. 11 is a partial side view of another embodiment of the present invention.

FIG. 12 is a partial side view of another embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Object plane 2 Image plane 10, 20, 30, 50, 60 Compound eye system 11-16 Inverted real image system A2-F2, A3-F3 Positions where optical members are arranged L1-L6 Rays on optical axis of inverted real image system

Claims (4)

[Claims] 1. A deflecting means having a plurality of optical members for deflecting a light beam in an optical path when projecting and superimposing an object plane on an image plane at a reduction or enlargement magnification by a compound eye system having a plurality of inverted real image systems. Then, the plurality of inverted real image systems are configured such that the light rays on their optical axes intersect each other in space, and each light ray on the optical axes of the plurality of inverted real image systems is at least one of the object plane or the image plane. And the plurality of inverted real image systems are composed of the same lens element and are arranged on different planes so that the respective optical path lengths are the same. A projection optical system characterized by. 2. The plurality of optical members are composed of a plurality of reflecting mirrors facing each other for each of the plurality of inverted real image systems, and the angles of the plurality of reflecting mirrors are changed for each of the inverted real image systems. The projection optical system according to claim 1, wherein: 3. The projection optical system according to claim 2, wherein the deflecting means is provided at least between the object plane and the compound eye system or between the image plane and the compound eye system. system. 4. The optical member comprises a reflecting mirror,
The projection optical system according to claim 1, wherein one reflecting mirror deflects a light flux passing through at least two of the plurality of inverted real image systems.