JPH0795158B2 - 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. FIG. 2 shows, for example, JP-A-5
It is a schematic diagram of the compound eye system in the erecting equal-magnification type proposed by the 5-83001 gazette. In the figure, reference numeral 20-1 denotes a compound eye system, which is composed of a plurality of erecting real image systems 21 including a light-condensing optical transmission body or microlenses. Then, each erecting real image system 21 projects a predetermined range of the object plane 1 onto the image plane 2 as an erecting equal-magnification image, and superposes them to form an integral image. As a result, a large object surface that cannot be covered by a single erecting real image system is projected onto the image surface.
Since the compound eye system shown in FIG. 2 has the same projection magnification, the optical axes of the respective erect real image systems 21 are configured to be parallel, and each light ray on the optical axis forms an object plane 1 and an image plane 2. It is configured to intersect vertically. 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.

However, in FIG. 2, when the object distance is changed in order to make the projection optical system a reduction system or an expansion system, the multiple images by the respective erect real image systems do not overlap on the image plane and are displaced, which is so-called ""Imageshift". The image shift phenomenon at this time is a cause of significantly deteriorating the optical performance of the projected image.

On the other hand, a method of correcting the image shift of the multiple images when performing the reduced projection or the enlarged projection using the compound eye system is proposed in, for example, Japanese Patent Laid-Open No. 57-16415.
In this publication, as shown in FIG. 3, a plurality of erecting real image systems 31 constituting a compound eye system 30 are provided, and an erecting real image system 310 whose optical axis is in the center.
Is arranged so as to gradually incline with respect to the optical axis 311 of the above, and thereby the shift of the multiple image is corrected. 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) differ for each erect real image system,
Further, in this compound eye system, when the light rays on the optical axis of the erecting real image system for projecting around the object plane intersect the object plane and the image plane, they largely deviate from the vertical. Therefore, as shown in FIG. 4, in the erecting real image system 41 whose inclination is large, the object surface having the same projection magnification is inclined from the normal object surface 1 and becomes like the object surface 42.

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 deviation occurs even if the deviation of the multiple images is corrected, and a projection image having high optical performance is obtained in the projection other than the 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 eccentric or the refracting power is added to reduce the magnification deviation. 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, a system in which a compound eye system composed of a plurality of erecting real image systems is used to correct the 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.

[0012]

SUMMARY OF THE INVENTION According to the present invention, when a compound eye system composed of a plurality of erect real image systems is used to project an object plane including a magnification other than equal magnification such as reduction or enlargement, an image of a multiple image is formed. An object of the present invention is to provide a projection optical system that improves the optical performance of a projected image by correcting the deviation and simultaneously reducing or eliminating the magnification deviation.

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 erecting real image systems and obtaining a good projection image as a whole. It is in.

[0014]

The projection optical system of the present invention comprises:
Optical paths between the object plane and the compound eye system and between the compound eye system and the image plane when projecting and superimposing the object plane on the image plane with the compound eye system having a plurality of erecting real image systems at a reduced or magnified magnification A deflecting unit having a plurality of optical members for deflecting a light beam is disposed therein, and each light beam on the optical axis of the plurality of erecting real image systems is configured to be perpendicular to the object plane and the image plane. The erecting real image system is composed of the same lens element and arranged on different planes so that the respective optical path lengths are the same.

In particular, each of the plurality of optical members is composed of a plurality of reflecting mirrors facing each other for each of the plurality of erecting real image systems,
The angle of the plurality of reflecting mirrors is changed for each erecting real image system, and the optical member is composed of reflecting mirrors,
It is characterized in that a light flux passing through at least two of the plurality of erecting real image systems is deflected by the one reflecting mirror.

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

[0017]

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 erect real image systems 11, 12, 13 ,.

Points A2, B2, C2, ... And points A3, B
3, C3, ... Are positions where optical members for arranging the light beams passing through the erecting real image system in respective 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 the present embodiment, the reflecting mirror is omitted for the sake of simplicity, and only the optical paths of light rays on the optical axis of each erecting real image system when reflected by the reflecting mirror are shown.

Points A1, B1, C1, on the object plane 1
... and the points A4, B4, C4, ... On the image plane 2 are the rays L on the optical axis of the erecting real image system 11, 12, 13 ,.
It is the position where 1, L2, L3, ...

In this embodiment, optical members are respectively arranged at points A2 to E2 with respect to one direction of points A1 to E1 on the object plane 1.
It constitutes one optical member row. The other one on the object plane 1
Similarly, with respect to the points F1 to J1 in the direction, the optical members are respectively arranged at the points F2 to J2 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 E3 similarly to the object plane 1 side, and one optical member row is made of a plurality of optical members arranged at points F3 to J3. 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 this 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 erecting real image systems for each optical member do not interfere with each other in space. is doing.

In the present embodiment, the predetermined range of the object plane 1 is arranged at the point C3 by the erecting real image system 13 via a reflecting mirror in which the object plane near the point C1 is arranged at the position C2 with a predetermined inclination. After being reflected by a reflecting mirror, a point C4 on the 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. Thus, the loci of the optical axes of the erecting real image systems exist on the same plane, and the projected images of the erecting real image systems are relatively rotated so as not to cause "rotation blur". These are exactly the same for other erecting real image systems, and a predetermined range of the object plane 1 is reduced and projected onto the image plane.

The ratio of the distance D _{A1, B1} between the points A1 and B1 on the object plane 1 to the distance D _{A4, B4} between the points A4 and B4 on the image plane 2 when the projection magnification is m. Is multiplied by m. 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 erecting real image system.

[0028]

[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 the present embodiment, the projection image on the image plane formed by each erecting real image system, that is, a so-called multiple image, is changed in shape and inclination of a plurality of reflecting mirrors provided on the object plane 1 and image plane 2 sides. As a result, they are overlapped with each other to form an integral image as a whole, thereby preventing image shift.

In this embodiment, the inclination of each erecting real image system and each reflecting mirror is such that the light rays L1 to L10 on the optical axis of each erecting real image system intersect perpendicularly with the object plane 1 and the image plane 2. Is set. That is, the light beams L1 to L10 on the optical axis of each erecting real image system are reflected by a reflecting mirror and then become parallel to each other and intersect perpendicularly to the object plane 1 and the image plane 2.

This prevents the occurrence of "magnification shift" which occurs when the light beam on the optical axis of the erecting real image system described in FIG. 4 intersects the object plane or the image plane at an angle. 7 is a top view of a portion corresponding to one direction of points A1 to E1 of FIG. 1 at this time, and FIG. 8 is a side view including points C1 and H1 on the object plane 1 of FIG.

In FIGS. 7 and 8, each reference numeral is exactly the same as that shown in FIG.

In FIG. 7, points A1 to E1 on the object plane 1
A straight line D11 connecting the points A4 to E4 on the image plane 2 is parallel to a straight line D41. Then, when the optical axes of the plurality of erecting real image systems 11 to 15 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 elements shown in FIG. 7, m = D72 / D71.

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

Positions A2, B2, C2, ... Of the respective reflecting mirrors
, And the positions A3, B3, C3, ... Can be arbitrarily set within the range that satisfies the formula (1), but once each position of one reflecting surface is determined, the rest depends on the characteristics of the erect real image system. You can decide sequentially.

It is needless to say that in this embodiment, two or more optical member rows may be provided in a step shape.

With the above-described structure, in this 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 at the same time, the light quantity distributions of the respective erecting real image systems are superposed. 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 erecting 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 above embodiment, from the first reflecting mirror having a separate reflecting surface for each erecting real image system to the last reflecting mirror passing through the erecting real image system to the last reflecting mirror having a separate reflecting surface. It is preferable to dispose a light shielding member to prevent crosstalk in the standing image system.

In the above embodiment, the case where the projection optical system is applied to the reduction system has been described. 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, one reflecting mirror may be used to deflect the light beams from a plurality of erecting real image systems if a slight image shift or magnification shift is allowed.

In the present embodiment, the case where the compound eye system is composed of 10 erecting real image systems is shown, but the object of the present invention can be achieved by providing two or more erecting 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 erecting 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.

[0048]

According to the present invention, when a compound eye system including a plurality of erecting 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. As a result, it is possible to achieve a projection optical system in which both the image shift and the magnification shift 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.

[Explanation of symbols]

1 Object plane 2 Image plane 10, 20-1, 30, 50, 60 Compound eye system 11-20, 21, 31, 51, 61 Erect real image system A2-J2, A3-J3 Position L1 at which optical members are arranged ~ L10 Rays on the optical axis of the erecting real image system

Claims (3)

[Claims] 1. When projecting and superimposing an object plane on an image plane with a compound eye system having a plurality of erecting real image systems at a reduced or magnified magnification, between the object plane and the compound eye system and between the compound eye system and the image plane. A deflecting means having a plurality of optical members for deflecting a light beam is arranged in an optical path between the optical path and the optical path of the plurality of erecting real image systems so that each light ray is perpendicular to the object plane and the image plane. A projection optical system is characterized in that the plurality of erecting real image systems are respectively composed of the same lens element and are arranged on different planes so that the respective optical path lengths are the same. 2. The plurality of optical members are constituted by a plurality of reflecting mirrors facing each other for each of the plurality of erecting real image systems, and the angles of the plurality of reflecting mirrors are changed for each of the erecting real image systems. The projection optical system according to claim 1, wherein the projection optical system is arranged as follows. 3. The optical member comprises a reflecting mirror,
2. The projection optical system according to claim 1, wherein a light flux passing through at least two of the plurality of erecting real image systems is deflected by one reflecting mirror.