JPH0614142B2 - Projection optics - Google Patents

Description

Description: TECHNICAL FIELD 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 and a facsimile, and in particular, Suitable for projecting the object surface onto the image surface at various magnifications such as reduction or enlargement by using a so-called compound eye system in which a plurality of lens elements including a condensing light transmission body or a microlens are arranged in a row. The present invention relates to a projection optical system.

(Prior Art) Conventionally, in an optical apparatus such as an electrophotographic copying machine or a facsimile, a compound eye system is used to project an object plane on an image plane at a predetermined magnification. FIG. 2 shows, for example, JP-A-55-8300.
FIG. 2 is a schematic diagram of a compound eye system in an erecting equal-magnification system proposed in Japanese Patent No. 1 publication. In the figure, reference numeral 20 denotes a compound eye system, which is composed of a plurality of erecting real image systems 21 composed of a light-condensing optical transmitter or microlenses. And each erect real image system 21
Thus, a predetermined range of the object plane 1 is projected on the image plane 2 as an erecting equal-magnification image, and the images are superposed 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. The compound eye system shown in FIG. 2 is constructed such that the optical axes of the erect real image systems 21 are parallel to each other because the projection magnification is 1 ×, and each ray on the optical axis is an object plane 1 and an image plane 2. It is configured to intersect vertically with. 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 enlargement system, the multiple images by the respective erect real image systems do not overlap on the image plane and are displaced, so-called "image displacement". 』Will come up. 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 for correcting the image shift of multiple images when the image is reduced or enlarged and projected by using a compound eye system is disclosed in, for example, JP-A-57-57.
It is proposed in Japanese Patent No. 16415. In this publication, as shown in FIG. 3, a plurality of erecting real image systems 3 forming a compound eye system 30.
1 is arranged such that its optical axis gradually inclines with respect to the optical axis 311 of the erecting real image system 310 at the center, whereby the shift of the multiple images 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) 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, as shown in FIG. 4, in the erecting real image system 41 having a large inclination, 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, an image plane having the same projection magnification is also a normal image plane 2
It tilts with respect to the image plane 43. As a result, a so-called "magnification shift" occurs in which the imaging magnification is partially different in the same visual field range by an amount corresponding to the difference between the optical path lengths l41 and l42 shown in FIG. 4 around the object plane. Come on.

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 it is difficult to obtain a projection image having high optical performance in the projection other than the equal magnification. ing.

Further, in the same publication, the entrance end surface or the exit end surface of each erecting real image system is decentered or a refracting power is added as necessary to reduce the deviation in magnification, but this is the entire projection optical system. Becomes complicated. And in principle,
Since the optical axis of each erecting real image system cannot be perpendicular to the object plane and the image plane, there is a limit to such correction, and it is difficult to largely eliminate the magnification deviation by such means.

In addition, a compound eye system composed of a plurality of erecting real image systems is used to correct image shift of multiple images when performing reduced projection or enlarged projection, for example, Japanese Patent Laid-Open Nos. 59-45420 and Sho. It is proposed in Japanese Patent Publication No. 59-216115.

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

Further, in Japanese Laid-Open Patent Publication No. 59-216115, as shown in FIG. 6, a plurality of spherical lenses 62 are provided on at least one of the object plane 1 side and the image plane 2 side of a compound eye system 80 including a plurality of erecting real image systems 61. A projection optical system in which 63 is arranged to correct the image shift of multiple images is proposed.

However, in the projection optical systems proposed in the above two publications, the erecting real image systems have different optical axis lengths,
Moreover, the optical axis of the erecting real image system that projects the periphery of the object plane is largely tilted 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.

(Problems to be Solved by the Invention) The present invention uses a compound eye system composed of a plurality of erect real image systems to project an object plane including a magnification other than equal magnification, such as reduction or enlargement, when forming an image of multiple images. 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.

(Means for Solving the Problem) The projection optical system of the present invention, 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 erect real image systems, A deflecting means having a plurality of optical members for deflecting a light beam is arranged in an optical path between the compound eye system and between the compound eye system and an image plane, and each light ray on the optical axis of the plurality of erecting real image systems is arranged. It is characterized in that it is constructed so as to be perpendicular to the object plane and the image plane, and that the plurality of erect real image systems are made up of lens elements having different optical characteristics and are arranged on the same plane.

In particular, the plurality of optical members are composed of a plurality of reflecting mirrors facing each other for the plurality of erecting real image systems, and the angles of the plurality of reflecting mirrors are arranged so as to be changed for each erecting real image system. In addition, the optical member is configured by a reflecting mirror, and the one reflecting mirror deflects a light flux passing through at least two of the plurality of erecting real image systems.

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

(Embodiment) FIG. 1 is a schematic view of an optical system of an embodiment when the projection optical system of the present invention is constituted by 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, B3, C3, ...
Is a position where optical members for deflecting the light fluxes that have passed through the erecting 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 simplification, and only the optical paths of the light rays on the optical axis of each erecting real image system when reflected by the reflecting mirror are shown.

In this embodiment, points A2, B2, C2, ... And points A3, B
Each of the plurality of optical members arranged in a line along C3, C3, ...

The points A1, B1, C1, ... On the object plane 1 and the points A4, B4, C4 ,.
Rays L1, L2, L on the optical axes of 1, 12, 13, ...
It is the position where 3, ...

In this embodiment, a plurality of erecting real image systems are made up of lens elements having different optical characteristics, and they are all arranged in the same plane. This simplifies the layout. The optical axis lengths of multiple erecting real image systems are different,
The optical axis length of the erecting real image system located in the center is the shortest, and the erecting real image system in the periphery is longer.

It should be noted that a plurality of erecting real image systems can be composed of lens elements having the same optical characteristics by newly bending a light beam using a reflecting mirror or the like.

In the present embodiment, a predetermined range of the object plane 1 is, for example, a reflecting mirror arranged at a 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 a position C2 with a predetermined inclination. After the reflection, the image is reduced and projected in the vicinity of the point C4 on the image plane 2. At this time, in this embodiment, points C1, C2, C
3 and C4 are arranged 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.

When the projection magnification is m, the points A1 and B on the object plane 1 are
Interval with 1 And the distance between points A4 and B4 on the image plane 2 The ratio with is set to m times. The same applies to the intervals at other points.

In the coordinate system shown in FIG. 1, for example, points B1, B2, B
3, when representing a B4 coordinate B1 = (x, l / 2 , h / 2) B2 = (x, l / 2, -h 1) B3 = (mx, -l / 2, h 2) B4 = ( mx, −l / 2, −h / 2).

At this time, 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 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 erecting real image systems, so-called multiple images, are changed by changing the shapes and inclinations of the plurality of reflecting mirrors provided on the object plane 1 and image plane 2 sides. Overlapping forms an integral image as a whole to prevent image shift.

Further, in this embodiment, the light ray L1 on the optical axis of each erecting real image system is
The inclinations of the erecting real image systems and the reflecting mirrors are set so that L5 intersects the object plane 1 and the image plane 2 at right angles. That is, the light rays L1 to L5 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" that 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.

FIG. 7 is a top view of FIG. 1 at this time, and FIG. 8 is a side view including the point C1 on the object plane 1 and the erecting real image system 13 of FIG.

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

In FIG. 7, points A1, B1, C1, ... On the object plane 1
A straight line D11 connecting the points and points A4, B4, C on the image plane 2
A straight line D41 connecting 4, ... Is parallel. .. are set so that the optical axes of the erecting real image systems 11, 12, 13, ...

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

Positions A2, B2, C2, ... And positions A of each reflecting mirror
3, B3, C3, ... Can be arbitrarily set within the range satisfying the expression (1), but once each position of one reflecting surface is determined, the rest is sequentially determined by the characteristics of the erecting real image system. be able to.

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 members 90 and 91 are used.
, The ray L3 on the optical axis of the erecting real image system 13 is converted into the object plane 1
Similarly, even if the image plane 2 and the image plane 2 intersect each other, the image shift and the magnification shift can be prevented.

In the above embodiment, each erecting real image system extends 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 and having a separate reflecting surface. 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, the present invention is applied in the same manner if the entire reduction system is reversed. can do.

In the present 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 overall arrangement of the projection optical system is arranged. May be set arbitrarily.

Such 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 the present 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 five 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 the present embodiment, two deflecting means are used and one reflecting mirror is used as one deflecting means. However, as described above, "rotational shake", "image shift", "magnification shift", etc. are corrected. Independently of the configuration, the object plane, and the image plane portion, a plurality of reflecting mirrors or refracting members may be used according to the equivalent configuration.
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. Further, as shown in FIG. 10 (B), 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. At this time, if the image of the line segment 101 of each object plane becomes one line segment 102 on the image plane 2 so that there is no so-called rotational deviation, an arbitrary configuration according to the relative positional relationship between the object plane and the image plane is obtained. Can be taken.

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.

(Effects of the Invention) According to the present invention, when a compound eye system including a plurality of erect real image systems is used to perform reduced projection or enlarged projection of an object surface, 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 view of an optical system of an embodiment of the present invention, FIG. 7 is a top view of FIG. 1, FIG. 8 is a partial side view of FIG.
FIGS. 10 (A) and 10 (B) are partial side views of another embodiment of the present invention, and FIGS. 2, 3, 5 and 6 are explanations of a part of a conventional projection optical system. FIG. 4 and FIG. 4 are explanatory views of a projected image of a part of FIG. In the figure, 1 is the object plane, 2 is the image plane, 10, 20, 30, 50,
60 is a compound eye system, 11, 12, 13, 14, 15, 2
1, 31, 51, 61 are erecting real image systems, A2, B2,
C2, D2, E2, A3, B3, C3, D3, E3 are positions where optical members are arranged, and L1 to L5 are light 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. In addition, the projection optical system is characterized in that the plurality of erecting real image systems are composed of lens elements having different optical characteristics and are arranged on the same plane. 2. The plurality of optical members are composed of 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, and the one reflecting mirror deflects a light beam passing through at least two of the plurality of erecting real image systems. The projection optical system according to claim 1.